# Turbojet powered cruise missiles



## kool kitty89 (Apr 24, 2015)

Moved from the other discussion given how far off topic it went, perhaps worth moving the discussion on chemical/nuclear weapons here too? (at least as far as their ability to be deployed on cruise missles)







kool kitty89 said:


> The tendency for V2s to bury themselves before detonating might have made them more effective as chemical weapons systems than conventional, or at least have a lesser detriment to effectiveness. Potential for the earth/debris to muffle the explosion and cause the dispersion of gas to be more focused at low level and remain concentrated around populated areas more, that and potentially contaminating groundwater.
> 
> One alternative to V1s might have been turbojet powered cruise missiles, something that may have been further benefited by the relatively low cost of materials and man-hours per engine for (and limited service life) of the Jumo 004B, or perhaps an even simpler specialized low-life engine that used even more mild steel in place of stainless alloys. (I do wonder how long a plain mild steel turbine might hold up when used in a similar air-cooled configuration, especially with zero concern for throttle changes further increasing wear)
> 
> ...





So, on top of that, use of easier to burn (yet still cheap to synthesize) fuels might have accelerated pulse jet and turbojet development and improved some of the reliability problems Heinkel was having early on, particularly those relating to unstable combustion and hot spots (enough to make the early test designs only work on hydrogen and still plaguing the HeS-8 for most if not all of its development period -in fact the problems with the HeS 8 seemed worse than those experienced when the previous HeS 3/6 program wound down). And while the HeS 3 and 6 were bulky, they were still relatively light and compact enough to be decent for high-speed configurations, and narrower than Whittle's designs. (perhaps better embedded in the body/tail of a missile than piggyback -the HeS 8 was much narrower but more troublesome, perhaps less so as a 'throw away' engine)

Aside from that, development of specifically designed, inexpensive, short-life engines may have bypassed the issues with usefully long service lives/TBO times and turbine wear issues, though developments focusing on even cheaper engines using less or no stainless steel in the hot section (something Heinkel's early designs used heavily) would have needed a bit of work. (with the superior wear characteristics of radial turbines, an uncooled steel bladed configuration may have been usable, and the disadvantage of sheer size/weight of costly stainless steel would be mitigated -in fact, you could increase the thickness of plain steel turbine in this case, compromising spool-up time, and adding to weight slightly, but being fairly unimportant for such a throw-away engine)


I should note that the HeS 3 of 1939 only produced slightly more than half the thrust of the 004B (about 990~1100 lbf) so the payload increases over the pulse jet powered V1 wouldn't be as great. (perhaps closer to a 50% gain plus improved range due to altitude and much better fuel consumption -even the crappy 1.6 lb/lbf/hr of Ohain's early engines was more than 2x as good as the Argus pulse jets)


Finally, mild steel is very easy to weld, so the quality/consistency advantages seen in the cromadur vs tinadur blades would have been relevant in spite of the low creep strength and oxidation issues. (this applies to a hypothetical mild steel turbine on the 004 as well) In fact, given there's zero nickel or other typically creep improving metals in cromadur, it may not hold up that much better under heat+stress than plain low carbon mild steel, with oxidation and related erosion being the main problem. (unimportant for an engine only intended to run for a couple hours at most -possibly unworkable if attempted on a combat aircraft though, aside from maybe a point interceptor that had engines/turbines replaced after each mission -I highly doubt even 10 hour service TBO would be reliable with such engines, Jumo worse than Heinkel given the cooling air might oxidize the turbine blades from within, plus the stresses are much higher than on the radial blades)


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## GregP (Apr 24, 2015)

V2's weren't powered by turbojets nor were they cruise missiles. The V2 was rocket powered and was a ballistic missile.

The V1's pulsetjet was very cheap compared with any jet engine and the aiming device was going to be the same. Why spend more for a 1-way weapon than you have to? And since the jet-powered one would be a bit faster with the same aiming device, the circle of error would be even bigger than it was, making them even less accurate.

I can't see what was wrong with the V1 as used other than needing a more accurate aiming system which it never got. Without that, airframe performance improvement would be largely a waste of effort if you hit even fewer of your targets than with the pulsejet version.

One thing they might have tried would be radio homing. By using German agents in the UK and setting up small transmitters that could be turned on some minutes before the V1 was expected overhead so it could home in on the expendable transmitter. I have no idea if they ever tried it, but it seems like maybe that would at least allow taking out some high-value targets ... assuming the small transmitters could be placed and the agents make an escape before being blasted themselves. Wouldn't work too often but it would keep the radio direction finders busy for a few minutes. It would have worked better with directional antennas ... at least until the British caught on and started looking at the UK from the direction of an incoming missile.

If they had tried that in concert with a jet-powered V1 ... maybe. But I still can't see what was wrong with what they really did versus the cost of doing it.

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## Milosh (Apr 24, 2015)

How accurate/inaccurate was the V1?


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## Shortround6 (Apr 25, 2015)

It had trouble hitting greater London, over 600 sq miles. Plenty did hit but a fair number did not. Makes the British night bombers (before radar) look like precision bombing.


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## Milosh (Apr 25, 2015)

Didn't the Brits have something to do with the V1s not hitting greater London?


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## GrauGeist (Apr 25, 2015)

The Germans were relying on impact data from their spies to give them feedback in order to adjust their targeting. However, all of the German spies stationed in England had been converted to double agents and were giving false impact reports.

And if anyone's ever curious about how many bombs fell on London, see this article and interactive map: The astonishing interactive map that show EVERY bomb dropped on London during the Blitz | Daily Mail Online

As far as accuracy, 5,091 V1 and V2 managed to find London and it's boroughs well enough.


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## GregP (Apr 25, 2015)

Overall, about 25% of the V-1's hit their target. So 15,000+ did NOT manage to hit London and its boroughs well enough. A good thing since that's a lot of warheads that could have done even MORE damage. *Edit*: This number can't be right as they didn't launch that many. I'll get back to it. but a LOT missed.

That is not very accurate, but does do some level of damage at 2,000 pounds per V-1. It's a decent-sized bomb any way you cook it.

Had they been going any faster, even MORE would have missed because of the added speed but the same timing accuracy.


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## stona (Apr 25, 2015)

GregP said:


> Overall, about 25% of the V-1's hit their target.



That figure is surely not including those destroyed by British defences. This is a map published showing the V-1s destroyed over Essex and its coast. It matches the official maps well, but has the grid and grid references removed for clarity as it was published in a local history book.







As the V-1 offensive really got underway on June 15th 1944, 244 V1's were launched from 55 sites. 73 hit Greater London and 71 hit areas outside of London. 100 V1's failed to get across the Channel. That does give an initial success rate of a little better than 25%, on a target the size of Greater London and before the British reacted with increased and coordinated defences.
To get an idea of the scatter gun effect of a V-1 attack, this map shows where the V-1s launched at Manchester fell on 24th December 1944. Only 1 of the 31 recorded actually landed in Greater Manchester.






Those unfamiliar with English geography should understand that the V-1s fell across at least five counties and that the backbone of Northern England, the Pennine Hills, runs down the country between Lancashire (Manchester) and Yorkshire (Leeds). It is a very lightly inhabited area, largely composed of moorland. Most of the V-1s fell across this area. Here's a picture, taken in 1993, of one of the impact craters on Midhope Moor which lies between Manchester and Sheffield.






It is just possible that a few sheep may have been inconvenienced by this particular V-1, as all the others that fell across the moors, but the British war economy certainly wasn't. On the same night the RAF sent 338 aircraft to bomb the airfields at Lohausen (Dusseldorf) and Mulheim (Essen) which certainly did inconvenience German efforts to fly supplies from the Ruhr to the Ardennes.

Cheers

Steve

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## rochie (Apr 25, 2015)

Going from memory, I think the total V-1's launched against England was just under 9000, killing around 6000 and wounding 3 times as many people


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## rochie (Apr 25, 2015)

This is sourced from the people's war Great Britain 1939-1945
A total of 9,251 V-1s were fired at targets in Britain, with the vast majority aimed at London; 2,515 reached the city, killing 6,184 civilians and injuring 17,981. Croydon to the south, on the flight path of the V1s suffered severely taking 142 hits.


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## tomo pauk (Apr 25, 2015)

Wonder whether the V-1 would've made sense as an anti-radiation missile?


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## rochie (Apr 25, 2015)

And for the V-2.
1,115 V-2s were fired at the United Kingdom. The vast majority of them were aimed at London, though about 40 targeted (and missed) Norwich. They killed an estimated 2,754 people in London with another 6,523 injured. A further 2,917 service personnel were killed as a result of the V weapon campaign. Since the V-2 was supersonic and could not be heard (and was rarely seen) as it approached the target, its psychological effect "suffered in comparison to the V-1


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## stona (Apr 25, 2015)

London was the principal target. 

Targets in the North were attacked using air launched V-1s which rather obviously reduced the numbers that could be launched. 

The Southampton-Portsmouth area was attacked with a few (22 seems most likely) ramp launched V-1s but Von Runstedt soon received a signal ordering the cessation of such launches which were seen as a diversion from the attack on London. Later Von Kluge did allow air launched V-1s to be used against the ports. They were also used against London which was a frivolous waste of the flexibility of this version of the V-1.

In the end the V-1s managed to deliver about 2,500 warheads to London over roughly a five month period. Call it 2,500 tonnes of explosives at a rate of about 500 tons per month. This is somewhat less than the tonnage of high explosive and incendiary ordnance dropped on Dresden on the night of 13/14 February '45 (2,660 tons).
During the same five month period as the V-1 offensive against London the RAF alone was dropping around 70,000 tons per month on targets in Germany and occupied Europe. 
Because the war was nearly won and because of the civilian casualties there is a tendency, most noticeably in Britain, to get the impact of the brief V-1 campaign out of proportion. I understand why the citizens of London, and Antwerp for that matter, might do this, but historians have no excuse.

Cheers

Steve

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## kool kitty89 (Apr 25, 2015)

GregP said:


> The V1's pulsetjet was very cheap compared with any jet rngine and the aiming device was going to be teh same. Why sped more for a 1-way weapon than you have to? And since the jet-powered one would be a bit faster with the same aiming device, the circle of error would be even bigger than it was, making them even less accurate.
> 
> I can't see what was wrong with the V1 as used other than needing a more accurate aiming system which it never got. Without that, airframe performance improvement would be largely a waste of effort if you hit even fewer of your targets than with the pulsejet version.


Wouldn't a somewhat larger missile allow for more options for practical guidance devices?

I also omitted the issue of turbojets having superior altitude performance on top of fuel consumption, though I'd assume increases in altitude would increase the target errors as well. (or I suppose it depends more on altitude, particularly where the most problematic wind/weather conditions tend to be)




> One thing they might have tried would be radio honing. By using German agents in the UK and setting up small transmitters that could be turned on some minutes before the V1 was expected overhead so it could home in on the expendable transmitter. I have no idea if they ever tried it, but it seems like maybe that would at least allow taking out some high-value targets ... assuming the small transmitters could be palced and the agents make an escape before being blasted themselves. Wouldn't wrok too often but it would keep the radio direction finders bust for a few minutes. It would have worked better with directional antennas ... at least until the British caught on and started looking at the UK from the direction of an incoming missile.


Wouldn't using pathfinder aircraft to drop beacons/transponders make more sense? (similar to the flares dropped by mosquitos)

Granted, then you get into jamming and decoy signal countermeasures being developed.




> If they had tried that in concert with a jet-powered V1 ... maybe. But I still can't see what was wrong with what they really did versus the cost of doing it.


It may have actually been faster to get a turbojet based missile operational. Pulse jets are extremely simple in operation, but making them useful and reliable is another matter (as it was, the German engines omitted a few extremely -mechanically- simple features that would vastly have improved performance -a simple 1-way valve for fuel injection control, and a thrust augmentor duct -combined, they could have nearly halved the specific fuel consumption while increasing thrust). The bigger issue though, was the vibration issues that created structural failure problems as well as some problems with the instrumentation.

Heinkel had simple, functional, flight worthy turbojets in 1939, not only that but the radial based turbine arrangement scales /down/ a lot more easily than axial turbines, so smaller engines than the HeS 3 or HeS 6 would have been possible. (significant if they did want to attempt turbojet powered missiles of approximately the same size as the existing V1)
Though making a somewhat larger design would probably be more advantageous.

And, of course, there's the fuel consumption and altitude performance advantages, plus turbojet exhaust is far less visible (though burning methanol or ether would make a far less visible flame than the V1's kerosene/gasoline) and with less noise. (though thrust augmentors tend to dampen both the flame and sound to some extent, those were never implimented by the Germans)

Another thought might be the possibility of a largely wooden construction missile (more than just the wings) with the engine buried in the fuselage reducing radar detection. (I don't think that would be practical with a pulse jet due to the vibration problems, but a turbojet has a lot more flexibility there)



I'm not saying it would be better in all respects than the V1, or that it would merit canceling pulse jet development entirely, but more that there were unique merits. (and on grounds of cost, may at least have still been far less expensive than the V2)




GrauGeist said:


> The Germans were relying on impact data from their spies to give them feedback in order to adjust their targeting. However, all of the German spies stationed in England had been converted to double agents and were giving false impact reports.


Wouldn't recon flights be a better measure of success, or even chase planes? Only jets would be able to actually keep up, but aside from that, you could still have prop based recon flights over the target area. (or launched ahead, with the missiles catching up on the target area around the same time as the recon craft)

You couldn't have recon flights following low, obviously, so weather/cloud conditions would determine ability to document the immediate effects on targets.


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## rochie (Apr 25, 2015)

Found this on Wiki.
A certain number of the V-1s fired had been fitted with radio transmitters, which had clearly demonstrated a tendency for the V-1 to fall short. Oberst Max Wachtel, commander of Flak Regiment 155(W), which was responsible for the V-1 offensive, compared the data gathered by the transmitters with the reports obtained through the double agents. He concluded, when faced with the discrepancy between the two sets of data, that there must be a fault with the radio transmitters, as he had been assured that the agents were completely reliable. It was later calculated that if Wachtel had disregarded the agents' reports and relied on the radio data, he would have made the correct adjustments to the V-1's guidance, and casualties might have increased by 50% or more


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## stona (Apr 25, 2015)

The V-1 had a substantial error on all axis. It wasn't just a matter of falling long or short. A typical map for the impacts on any one attack, discounting those that fell more than 40 miles from the target, generally takes the shape of an ellipse, typically about 30-40 miles long and about 10 miles wide at the widest point. Considering the V-1s had usually flown less than 200 miles from launch this is not impressive. Obviously bringing the centre of the ellipse directly over the target _might_ increase the number of impacts on the intended target, but I'd love to see some proper data for the notion that casualties could have increased by 50%. It is NOT the same as bringing the centre of bombing from a reasonably concentrated air raid back (or more likely forward) to the aiming point.

Range did have an effect on accuracy. I have one map showing V-1 impacts _after_ the French bases were lost to the Germans. The V-1s fell over an area extending from 50 miles north to 40 miles south of London and back to the east coast both north and south of the Thames estuary (there is no way to accurately work out how many fell into the sea). Few fell much to the west of London which means that as they were approaching from a more or less easterly direction they tended to fall short rather than fly long. It's still a huge area in which covers Hertfordshire, Essex, Surrey, Kent and East Sussex as well as Greater London itself.

Cheers

Steve


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## Shortround6 (Apr 25, 2015)

It kind of depends on the definition of 'accuracy' or what the standard is. The V-1 _as used_ was useful for targeting a very large city _AND_ it's close suburbs. It wasn't much good for anything smaller.

For some perspective greater London is about 609 sq miles, New York City is 469 sq miles. Against New York the V-1 would have been in position of one missile hitting Staten Island and the next one off the launcher hitting the Bronx or worse. 

It killed and wounded people and caused property damage and a great deal of resources to be tied up countering it but those are different than accuracy.


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## stona (Apr 25, 2015)

Shortround6 said:


> It kind of depends on the definition of 'accuracy' or what the standard is. The V-1 _as used_ was useful for targeting a very large city _AND_ it's close suburbs. It wasn't much good for anything smaller.



As illustrated by the Southampton-Portsmouth attacks. Of the 42 V-1s that actually fell on land between 10th and 15th July none impacted within the extensive docks area. 

Some damage and casualties were caused. On the night of 14th/15th July the worst incident caused fifteen deaths and ninety eight wounded when a V-1 came down in Newcomen Road, Portsmouth. This one was close to the docks, but nowhere near close enough to do any damage to the naval installations.

Cheers

Steve


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## Shortround6 (Apr 25, 2015)

That rather illustrates the problem with attacking a coastal city because the if the center of the ellipse is the docks in the center of the ellipse then roughly 1/2 of the fired missiles will fall into the sea to begin with. To get 42 missiles to fall on land how many were fired?


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## pbehn (Apr 25, 2015)

There are some areas in London that are densely populated but even today in greater London there a lot of open spaces.


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## Juha (Apr 25, 2015)

kool kitty89 said:


> ...Wouldn't recon flights be a better measure of success, or even chase planes? Only jets would be able to actually keep up, but aside from that, you could still have prop based recon flights over the target area. (or launched ahead, with the missiles catching up on the target area around the same time as the recon craft)
> 
> You couldn't have recon flights following low, obviously, so weather/cloud conditions would determine ability to document the immediate effects on targets.



Why you think the Normandy landings were such a surprise, Germans were incapable to make recon flights over over Weymouth - Selsey area during spring early summer 44, say nothing on London. Only the arrival of Ar 234 changed the situation.


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## FLYBOYJ (Apr 25, 2015)

To answer the original question, given the technology of the day, it was a waste of time and resources to even consider a turbojet engine for a cruise missile like the V-1. It wasn't until long after the war when companies like Williams and Turbomeca produced small, relatively cheap and efficient turbojet engines that were way more practical for cruise missile application.

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## Shortround6 (Apr 25, 2015)

The idea was there earlier, Like the Fairchild J44 and the Westinghouse J32 ( 9.5 or 9.5A, only 9.5 on on diameter) but getting engines that worked and were cheap enough to be expendable may have been a problem in the early years.


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## FLYBOYJ (Apr 25, 2015)

Shortround6 said:


> cheap enough to be expendable



that's the key...


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## pbehn (Apr 25, 2015)

Juha said:


> Why you think the Normandy landings were such a surprise, Germans were incapable to make recon flights over over Weymouth - Selsey area during spring early summer 44, say nothing on London. Only the arrival of Ar 234 changed the situation.



The Germans didnt need recon in 1944 they already knew exactly where the allies were and what they were going to do. Unfortunately most of the info was bogus. By the summer of 1944 Hitler was actually listening more to the British secret service than he was to his own staff, facts played only a small part in the situation.


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## stona (Apr 25, 2015)

Shortround6 said:


> That rather illustrates the problem with attacking a coastal city because the if the center of the ellipse is the docks in the center of the ellipse then roughly 1/2 of the fired missiles will fall into the sea to begin with. To get 42 missiles to fall on land how many were fired?



The best estimate for this series of attacks is 110-120 V-1s launched. Of these 22 were ramp launched, the rest air launched. 

On these attacks the ranging was fairly good but the accuracy was not. 73% of the 42 impacts were within an ellipse measuring 8 x 33 miles with it's centre about 8 miles north east of Southampton. The British were uncertain whether Portsmouth or Southampton was the intended target and the composite 'Portsmouth-Southampton area' appeared in initial reports. Later analysis showed that just under half the impacts occurred within a circle whose centre lay 3 miles north of the mouth of the River Itchen, leading to the correct conclusion that Southampton was the target.

One V-1 did in fact fall not in the sea but in the River Test (south of Southampton) which must have made quite a splash 

This map shows the impacts for the attacks in question. It also shows where III./KG3 were launching their V-1s, outside the range of British radar (they hoped).







As someone has said, it makes no economic sense to fit an expensive turbo jet to a system which promised, and delivered, so little in return. Unless the problem of the gross inaccuracy of the system could be overcome it would have been an even bigger waste of valuable resources than the V-1 programme already was.

At least as we can see from the map, all these V-1s did fall in the same county, Hampshire!

Cheers

Steve

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## GrauGeist (Apr 25, 2015)

Juha said:


> Why you think the Normandy landings were such a surprise, Germans were incapable to make recon flights over over Weymouth - Selsey area during spring early summer 44, say nothing on London. Only the arrival of Ar 234 changed the situation.


There were Luftwaffe recon flights over Britain before the Ar234.

The British were creating a massive deception to lure the Germans away from the Normandy invasion preparations, so when Luftwaffe overflights spotted any of the Normandy assemblage, it was dismissed.


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## Juha (Apr 25, 2015)

pbehn said:


> The Germans didnt need recon in 1944 they already knew exactly where the allies were and what they were going to do. Unfortunately most of the info was bogus. By the summer of 1944 Hitler was actually listening more to the British secret service than he was to his own staff, facts played only a small part in the situation.



No they don't, that's why Heer was demanding early June 44 daylight recon flight over Southern England ports others than Dover area, from the latter area they had some photos. They had made recon flights off the coast but those didn't produce info the Heer wanted.


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## pbehn (Apr 25, 2015)

Juha said:


> No they don't, that's why Heer was demanding early June 44 daylight recon flight over Southern England ports others than Dover area, from the latter area they had some photos.



The point I was making was that you do recon to decide strategy and tactics. Hitler had been convinced that the main attack would be across the Pas de Calais and so any recon would be ignored. Hitler controlled the disposition of the tanks, even after D Day he was moving tanks away from Normandy, towards Calais. Given that, any recon would only "prove" Hitler was correct because proving a mad man to be wrong is dangerous.


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## stona (Apr 25, 2015)

I don't see how aerial reconnaissance to do a sort of bomb damage assessment for the V-1 strikes could possibly have worked. Just look at the distribution of the impact points. The 42 V-1s that fell around Southampton were in an area roughly 33 miles by 5 miles! An aircraft making a pass over Portsmouth or Southampton, or flying up the Thames estuary to make a few passes one side or another of the river _would be lucky to distinguish any damage caused by the V-1 strikes._ It's hardly like flying over Hamburg or Dresden to assess the effects of a conventional strategic bombing strike. An aircraft that flew over London, Manchester or Southampton would probably conclude that all the weapons had missed. I don't think some here have grasped just how inaccurate the V-1 system was.
The Germans would have needed squadrons of reconnaissance aircraft overflying the entire area of the Home Counties (those that surround Greater London) to have any idea where the V-1s were landing. The RAF might have had something to say about that. It's a ridiculous undertaking.
Cheers
Steve

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## Juha (Apr 25, 2015)

pbehn said:


> The point I was making was that you do recon to decide strategy and tactics. Hitler had been convinced that the main attack would be across the Pas de Calais and so any recon would be ignored. Hitler controlled the disposition of the tanks, even after D Day he was moving tanks away from Normandy, towards Calais. Given that, any recon would only "prove" Hitler was correct because proving a mad man to be wrong is dangerous.



IIRC it was other way around, von Rundstedt co thought that attack would be across the pas de Calais and Hitler got, at least initially, an intuition that the target will be Normandy. And AG B (Rommel) decided the placement of the 3 PzDivs under his command 21st, 116th and 2nd, all three rather near to the coast for rapid a counterattack but dispersed along the coast, because the actual place of the invasion was unknown to germans.


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## pbehn (Apr 25, 2015)

Juha said:


> IIRC it was other way around, von Rundstedt co thought that attack would be across the pas de Calais and Hitler got, at least initially, an intuition that the target will be Normandy. And AG B (Rommel) decided the placement of the 3 PzDivs under his command 21st, 116th and 2nd, all three rather near to the coast for rapid a counterattack but dispersed along the coast, because the actual place of the invasion was unknown to germans.



from wiki

On 9 June (3 days after D-day), Garbo sent a message to German High Command that reached Adolf Hitler[24] saying that he had conferred with his agents and developed an order of battle showing 75 divisions in England—in reality, there were only about 50. Part of the "Fortitude" plan was intended to convince the Germans that a fictitious formation—First U.S. Army Group, comprising 11 divisions (150,000 men), commanded by General George Patton—was stationed in the south and east of Britain.[3]

The deception was supported by fake planes, inflatable tanks and vans travelling about the area transmitting bogus radio chatter. Garbo's message pointed out that units from this formation had not participated in the invasion, and therefore the first landing should be considered a diversion. A German message to Madrid sent two days later said "all reports received in the last week from Arabel [Pujol's German code-name] undertaking have been confirmed without exception and are to be described as exceptionally valuable."[2] A post-war examination of German records found that, during Operation Fortitude, no fewer than sixty-two of Pujol's reports were included in German military high command intelligence summaries.[39]

The German High Command accepted Garbo's reports so completely that they kept two armoured divisions and 19 infantry divisions in the Pas de Calais waiting for a second invasion through July and August 1944. The German Commander-in-Chief, Field Marshal Gerd von Rundstedt, refused to allow General Erwin Rommel to move his divisions to Normandy.[3] There were more German troops in the Pas de Calais region two months after the Normandy invasion than there had been on D-Day.

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## nuuumannn (Apr 25, 2015)

> The V-1 as used was useful for targeting a very large city AND it's close suburbs. It wasn't much good for anything smaller.



Yep. It's worth remembering that the V 1 was very simple technology, even for 1943/1944. Any country with a modern aircraft industry could have built it, it's just the Germans managed to put it into service before anyone else. Although fitted with a simple auto pilot, the 'guidance' system wasn't so much about guidance as pointing it in the right direction and fingers crossed it didn't stray off course. It was aimed in the general direction of London and fired. It worked on the simple principal of the known distance to London from the launch point and the time it took to get there based on a given speed. This was counted down on a counter driven by the wee propeller in the nose and once this ran out, the fuel lines to the motor were cut, spoilers under the hori stab were deployed and the thing tipped over into a terminal dive.

It's also worth remembering that the V 1 and to a degree the V 2 were terror weapons, post raid recon wasn't going to reveal much; the damage done was intended to be partially psychological, so an assessment of fallen rubble isn't going to tell you how the population are coping with the impact of the campaign. Both weapons were too inaccurate and inconsistent for a major strategic bombing campaign with tangible results toward German victory to be carried out, although it was hoped beyond hope that this might result, of course. 

German reconnaissance was carried out over the British mainland throughout the war, but the results were indifferent to the point of being useless, since most attempts to undertake flights into British airspace were curtailed by the aircraft being intercepted. In 1944 a lone Bf 109 was shot down over England and crashed; the Brits were surprised to find it had a camera in the aft fuse - this is well known about the '109 of course, but it does scupper the theory that the Germans weren't at least trying to take images over Britain during the war.


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## stona (Apr 26, 2015)

nuuumannn said:


> It's also worth remembering that the V 1 and to a degree the V 2 were terror weapons, post raid recon wasn't going to reveal much; the damage done was intended to be partially psychological, so an assessment of fallen rubble isn't going to tell you how the population are coping with the impact of the campaign.



If the reconnaissance could identify the rubble!

On a good day 100 V-1s could be launched against London. If an optimistic 25% managed to fall within the Greater London Area the reconnaissance aircraft would be looking to photograph just 25 sites in an area of over 600 square miles. Not likely.
If they wanted to assess the overall accuracy they would have to identify other sites thinly spread over the Home Counties, thousands of square miles. That's not unlikely, it's impossible.

Cheers

Steve


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## Juha (Apr 26, 2015)

Hello pbehn
yes, Operation Fortitude succeeded well over Allied initial expections but that wasn't only because Hitler but also OB West believed at least some time to it. I was thinking the time before D-Day, when OB West (von Rundstedt co) believed that Pas de Calais would be the target, IIRC Rommel vacilitated between Pas de Calais and Normandy and Hitler, at least in early 44, intuitively thought that Allies will land in Normandy. The inability of LW to make proper recon over Southern England coast made the success of Operation Fortitude much easier before and after D-Day.


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## Juha (Apr 26, 2015)

nuuumannn said:


> ...German reconnaissance was carried out over the British mainland throughout the war, but the results were indifferent to the point of being useless, since most attempts to undertake flights into British airspace were curtailed by the aircraft being intercepted. In 1944 a lone Bf 109 was shot down over England and crashed; the Brits were surprised to find it had a camera in the aft fuse - this is well known about the '109 of course, but it does scupper the theory that the Germans weren't at least trying to take images over Britain during the war.



IIRC theBritish were well aware of LW's attemps to daylight aerial recons over England via radar and Ultra, besides 109 they tried Ar 240 and 190s. LW got some photos at least on Kentish ports.


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## kool kitty89 (Apr 26, 2015)

FLYBOYJ said:


> To answer the original question, given the technology of the day, it was a waste of time and resources to even consider a turbojet engine for a cruise missile like the V-1. It wasn't until long after the war when companies like Williams and Turbomeca produced small, relatively cheap and efficient turbojet engines that were way more practical for cruise missile application.





Shortround6 said:


> The idea was there earlier, Like the Fairchild J44 and the Westinghouse J32 ( 9.5 or 9.5A, only 9.5 on on diameter) but getting engines that worked and were cheap enough to be expendable may have been a problem in the early years.


The designs Ohain was working with pre-war aren't all that far from the simpler/smaller range of designs that appeared post-war, even more similar to some of the smallest turbojet designs ever mass produced. (in part due to radial inflow turbines being more practical to use at those scales -they also ended up taking over most automotive turbocharger designs and I do wonder if Hirth considered applying them to their own turbocharger developments)

They were not particularly high tech, refined designs either ... and some of the innovations came less from engineering and more common sense mechanic/technician input. (the first functioning liquid fuel combustion chamber used burners adapted from the design of Otto Han's blow torch, even relying on hydrogen for the warm-up period before gasoline/kerosene could vaporize properly -similar to using methanol/ethanol in the spill pan of a torch -you can use gasoline too, but it's horribly sooty and can foul the fuel jet ... the very problem Ohain ran into when trying to start the engines using gasoline)
Still, I'm slightly surprised they hadn't attempted propane, butane, ether, or alcohol fuels to expand testing beyond hydrogen both for warm-up and for higher power compressor/turbine tests while the combustion chamber was being refined.


Granted, all work was being focused on engines suitable for manned (re-usable) aircraft, not missiles, and there's probably a better argument for using jet powered bombers than cruise missiles. (even with the poor fuel consumption, and fairly large frontal area/thrust ratio, if they could have refined the HeS 3 or HeS 6 for mass production rather than hitting the many many snags it took to getting the HeS 8 even to flying condition, they might have had useful short-life/frequent TBO engines much earlier in the vein of the earliest production 004Bs -albeit you'd need 4 to power a light/medium bomber ... but all the better for limping home in the case of in-flight failure)
I believe I've seen reference to Heinkel targeting a 10 hour TBO/service life as the minimum for practical military use.

Heinkel might have gained more RLM interest with a bomber than a fighter too. (and the way Ohain's engines were designed, they were very well suited to the sheet-metal working equipment of Heinkel's airframe facilities, adding potential for at least limited mass production before the Hirth Acquisition -the latter should have helped improve a lot of the engineering difficulties though, including with the compressor, diffuser, and turbine -or perhaps convinve Ohain to consider a centrifugal compressor + axial turbine layout for larger designs -plenty to go off from Hirth supercharger and turbocharger developments)

I'm off topic again here, though ... and I suppose a dedicated early-war Heinkel Jet Bomber 'what if' deserves its own thread anyway.







stona said:


> I don't see how aerial reconnaissance to do a sort of bomb damage assessment for the V-1 strikes could possibly have worked. Just look at the distribution of the impact points. The 42 V-1s that fell around Southampton were in an area roughly 33 miles by 5 miles! An aircraft making a pass over Portsmouth or Southampton, or flying up the Thames estuary to make a few passes one side or another of the river _would be lucky to distinguish any damage caused by the V-1 strikes._


Might using recon flights able to follow/detect the V-1s with radio transponders be more useful? (corroborating the results of the data being sent back)


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## stona (Apr 26, 2015)

kool kitty89 said:


> Might using recon flights able to follow/detect the V-1s with radio transponders be more useful? (corroborating the results of the data being sent back)



It would be a high risk method of corroboration, if the Germans felt that to be necessary. I have no idea how many V-1s were equipped with transponders. Given the wild inaccuracy of the weapon it would have to be a large number to give any sort of statistically useful data.

Cheers

Steve


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## pbehn (Apr 26, 2015)

stona said:


> It would be a high risk method of corroboration, if the Germans felt that to be necessary. I have no idea how many V-1s were equipped with transponders. Given the wild inaccuracy of the weapon it would have to be a large number to give any sort of statistically useful data.
> 
> Cheers
> 
> Steve



From what I read when the (accurate) results from the transponders disagreed with the (inaccurate) on the ground reports they believed the false reports, presumed the transponders were not working and stopped using them.


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## yulzari (Apr 26, 2015)

One of the issues faced by British air defence in 1944 was the necessity to allow some Luftwaffe photo recce to find the fake aeroplanes, tanks, ships etc. of Operation Fortitude whilst stopping them finding the scale of the real resources. Letting them photograph the fake stuff and stopping them photographing the real items would send a message any german intelligence staff could read. A fine balance. And the some of the recce missions over the fake stuff have to be intercepted to display that they were defended. No way could interceptors be called off when in action as their radio was monitored in real time by the Germans. It had to be the ground directing staff who 'filtered' the intercepts.


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## Juha (Apr 26, 2015)

Yes, it is difficult to say to what extent the following were results of intentional "failures" of the ADGB or real successes of the LW: Rommel's weekly situation report issued on 5 June (page 229): "Air reconnaissance showed no great increase of landing craft in Dover area. Other harbours of England's south coast not visited by reconnaissance aircraft." The report continued "Survey urgently needed of harbour moorings on the entire English south coast by air reconnaissance." Once the Invasion got under way efforts were made to photograph UK harbours and the kentish port of Ramsgate was covered by 5/123 (7th June 1944 Sortie F29/44, pilot Uffz Kallenberger, Height 750m; photos 753 and 754 used in report on the shipping there.


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## stona (Apr 26, 2015)

The problem is that even knowing that the ports of the South Coast were full of vessels and knowing that an invasion was imminent doesn't tell you where the landings will be made.

The German High Command was obsessed with the Calais area. As late as 18th May, in an evening situation report at the Berghof the report for the West was all about beach reconnaissance. The only one sceptical of the Pas de Calais region being the intended invasion area was Hitler himself.

_"Today there were two reconnaissance missions - rather we can't call them missions. They were attempts to locate obstacles of the coast and to photograph them. A patrol of the 18th Luftwaffe Field Division on the left wing eastward of Calais noticed some movement. An exchange of fire occurred. First we thought they were our own forces, clashing with each other. But flash bulbs, spades and American flashlights were found, one man was wounded, so we have to assume that Americans had tried to photograph the obstacles. Likewise two British officers were captured at the mouth of the Somme. They had gone in with a rubber dinghy and, according to interrogation completed so far, had been dropped by a British motor torpedo boat." _

The date is important. The actual reconnaissance of the real intended invasion beaches had been completed just two days earlier, so these 'raids' must have been part of Operation Fortitude. It was also just one day after the date for D-Day, initially June 5th, had been set by Eisenhower.

Cheers

Steve


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## pbehn (Apr 26, 2015)

stona said:


> The problem is that even knowing that the ports of the South Coast were full of vessels and knowing that an invasion was imminent doesn't tell you where the landings will be made.



Very true

The sailing distance from the Solent to Normandy and to Pas e Calais is pretty similar. Starting the invasion from Dover would mean loading ships in sight of the Germans.


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## stona (Apr 26, 2015)

Also due to ULTRA we knew what they _thought_ they knew. This is an excerpt from a report for the Prime Minister dating from May '44. It shows what the German reconnaissance had achieved and exactly what they knew.

Catalogue reference: HW 1/2784 (May 1944) in the National Archives.







Cheers

Steve

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## Koopernic (Apr 26, 2015)

There was a turbojet program for the V1.

A Porche design, the 109-005 and a BMW design, the P3006. Both 2 hour life disposable. The 109-005 designer was Max Mueller, who had joined from Heinkel Hirth.

The V2 required 280 man-hours to build, maybe 400 with autopilot. A BMW 003 required 700 hours, less than a piston engine, a disposable engine less again. A turbojet powered V1 would not cost much more than a pulse jet V1. German manned jet engine designs were preparing 2 hour life disposal steel turbine blades if they ran out of refractory alloys.

The V1 also known as the Fiesler Fi 103, Kirschkern (Cherrystone, its code name) was to be guided.
Standard propulsion was the Argus Reed Valve Pulse Jet. Speed was 390mph at low altitude. Improvements in the engine let experimental V1 achieve 515mph at low altitude in Feb 1945; almost impossible to intercept except for by a clipped wing Meteor III with Derwent V,ie Meteor IV. The engines that were testing late 44 would have knocked piston fighters, Meteor III P-80A out.

Control of the V1 was by a pneumatically powered gyroscopic autopilot whose course was set by magnetic compass. A propeller anemometer drove a 25:1 gearbox which turned a threaded rod that moved a nut along its length. The nut initiated switches which sequenced the flight. 
A modification which allowed in flight course changes was introduced. The V1 now flew a dog leg path to prevent the use of radar plots to back track to the V1 launch site.

A radio beacon was provided in 1 in 50 launches of the V1 called Ewald I so as to track several missiles and then, having the deviations of the missiles, to adjust subsequent launches. Towards the end of the V1 campaign 1 of 2 V1s carried Ewald I suggesting that the Germans had begun to suspect the double cross system that British Intelligence used to spoof the German aim points.

The double cross system involved using double agents reporting incorrect impact data to the Germans. 
For V1 impacts the wrong location was reported.
For V2 impacts the correct time but a selective location of a impact was reported.
Arado 234 equipped with timed cameras could record the impact points, although used over Europe they did not seem to be used over Britain. Erich Sommer returned in an recon Arado 234 a few years after doing so in a Ju 86. There were several ground based systems in development to track actual impact points.
The disposable turbojet allowed a longer range; increased speed and its lack of vibration did not disturb the guidance system. 
Ewald I guidance couldn't alter the path of the V1 once launched. However a second generation system called *Ewald 2* could. 

Ewald II was designed to be jam resistant. Neither missile nor ground station emitted a signal for most of the flight. At a coordinated time the V1 would emit a coded pulse which was received by 3 ground stations. The difference in arrival times between the three stations allowed a simultaneous equation to be calculating the missile position. A course correction was then sent to the missile, which had a decoding device based on an endlessly circulating loop of magnetic tape with a high frequency bias. It couldn't be spoofed and jamming and drowning out the signal would have been difficult. The ground stations had been built. In theory this midcourse system could be used near the target for terminal accuracy. A further development was to add a system that allowed up to 5 slave V1's to follow the Ewald II guided V1.

There were two terminal homing warheads "Raddischien" or Radish for homing on the allied radar and guidance beacons (tested on a BV246 glide bomb) and MAX-P for homing on to allied microwave systems that might be used in the V1.

A V1 with turbojet, extra fuel and Ewald II guidance might have been launched against Britain from bases in Germany. The range of a radio guidance system is determined by the radar horizon: the higher one goes the further the horizon. 
Willy Messerschmitt wrote to Gerhard Fieseler, congratulating him on his work, and saying that while he didn't want to interfere he would be pleased to help by sending over his engineers. The designer of the Fi 103 was Robert Lusser who had designed the Bf 109 with Willy Messerschmitt. 
Willy Messerschmitt ventured that as the USA could build 4.8 million cars annually that Germany should be able to build 1.2 million V1s per year; 100,000 monthly. 

(Had relations been better and Jeremy Clarkson willing 1.2 million free Volkswagens could have been sent over instead.)
_The reason these weapons were called "Vergeltungs Waffen" or Reprisal Weapons and were used before the introduction of accurate guidance was the from 1941/42 the British strategy of "Area Bombardment" whose purpose was "Dehousing" and "Demoralisation". These terms are the terms used in the British policy and strategy documents.
This was new though not unexpected. Up until that time if the RAF bombed the airport at Berlin or Siemensstadt or the Luftwaffe bombed say the Docklands in London or Portsmouth which were bringing in munitions and supplies or the machine tools and engine parts factories in Coventry the target was an military target or had direct economic or military logistic consequences. The damage to nearby suburbs and housing either collateral damage or damage deemed necessary as part of taking out the targets value since housing and the occupants of the nearby housing were generally closely unavoidably associated in that activity and in housing adjacent to the walls of the factory as were the roads, rail, bridges and other infrastructure within the immediate vicinity.
Area Bombardment, as Arthur Harris plainly explained in his memoir about the targeting bombing of Lubeck, meant that no specific target was chosen, the geometric centre of the city was chosen and destroyed by concentrating in enough bombs, incendiaries in a short enough time to create a fire storm. The true meaning of the terms 'dehousing' and 'demoralisation' should be clear.

This marked a complete change, it was the British, at the urging of Lord Cherwell (Lindeman) and Churchill that first did it. These decisions were taken just as systems such as Oboe, H2S were promising to give alternatives (hence disquiet in the British camp). Those taking the anti German side will point to cities such as Rotterdam, Guernica, and Coventry but in each case there had been a specific military purpose. Rotterdam had been surrounded by German troops who had to keep moving (to get to the coast and prevent a possible British counter attack) and negotiations had gone on for 2 days while ultimatums had passed several times. No one sends in their lads to get killed in street to street fighting walking into well bunkered enemy with ambush positions without a prior bombardment. Street fighting is messy to say the least.

Coventry Ordnance Works produced 25% of Britain's aircraft, even more of its machine tools other armaments. The night bombing opperation "Moonlight Sonata" using x-geraet blind and marker bombing destroyed it and 1/3rd of Coventry's Armaments factories, damaged another 1/3rd. There were sadly about 580 dead. While every life counts and causes pain it’s clear that the human cost was equal to a modern Jumbo Jet collision rather than the horror of tens of thousands dead civilians (mostly women, children old men, fighting age men were at the front) that came to be normal. Having said that, Goebbels’s propaganda about Covencation didn’t help.
Area bombardment didn't start the killing and bombing of civilians but it raised the number killed by *two orders of magnitude.* since civilians were now no longer collateral damage but the primary target itself.
Thus Germans didn't initiate a policy of Area Bombardment or even bombing of civilian industrial targets but they did initiate retaliation beginning with the Baedecker Raids after the Area Bombardment of Lubeck and Rostock. The Germans didn’t initially assumed it was an attack on cultural areas. The initial V1 and V2 campaigns were area bombardment campaigns that were to be bargaining chips and eventually more accurate weapons campaigns _ that could hit a a large factory.

The V2 was more costly than the V1. Whereas a V1 might cost 400 man hours to make the V2 was costed at 10,000, though it was to drop to 4000 hours per unit after the 10,000th V2. V1’s would also drop, long range versions had a wooden nose cone.


V2 guidance improvements involved gyroscopes, accelerometers, better ball bearings, fluid bearings, introduction of a gimballed gyroscopic platform with lateral accelerometers and a system which used beam riding and Doppler, the "wireless canon barrel" . Both aiming for 500m accuracy.

The A4b, the winged V2, added both range and the ability to be targeted to 180m. It was to be a midcourse guidance inertial system but initially they would glide to the target area such that at 15,000m altitude the missile would do a pull up, connect with the radar signal then a final vertical dive to the target. Guidance was by three giant Wassermann radar aerials laying on the side to obtain 0.01 degree accuracy.

A workforce of 10,000 could theoretically produce 100 V2s per week whereas the same workforce producing V1s would produce 1000.
A 4 engine bomber such as a Lancaster cost 20,000 man hours. It might survive 50 missions i.e. 400 man hours per mission. A crew of 7-10 would consume between 280 to 400 hours in the week between their 50 missions just recovering, briefing and training. There would be maybe 100 man hours per mission in maintenance and as much again in provision of spare parts, ammunition, rescue services. For each mission flown there would be dozens of hours per man in training.

Hence a manned bomber mission would be costing 800 man hours not counting airfield defence, training etc, radar jamming aircraft.


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## GregP (Apr 26, 2015)

I was on a team that restored a pulsejet for the Planes of Fame. We had 10 people researching the V-1 not including the 3 team members and we never uncovered a 515 mph V-1 of any sort.

So, I'd be interested in that if you could point me to a source that I can obtain and study. I see the 390 mph above but wartime production V-1s usually cruised more around 360 - 375 mph as far as we could uncover from German documents.

If you want to see our results, search Goolge Video for Chino Pulsejet. We also filmed one night run and it is interesting. There was no manual and it took us about a year to figure out how to start it and then another month and a half before we figured out how to get it from idle to full power. We ran it on both 87 Octane unleaded and 100 Octane unleaded. It preferred 87 Octane fuel and ran just fine. 2.2 gallons per minute at idle and 3.3 gallons per minute at full power. We only ran ours untl the internal temperature got to 1,100°F and then shut it off to save the reed pedals. That gave us about a 1.5 minute run while standing still and the temp was down by some 300°F when we ran down the runway at maybe 25 mph. Interestingly enough, the small forward speed combined with the new cowling we made increased thrust by about 25%. We had a thrust measuring setup on the test stand using a spring with a know spring constant and a linear hydraulic cylinder to get the spring compression. We calibrated it to about ±1%. The principle in that restoration was Robin Scott. Bob Velker and I helped Robin for about the last 6 months and all the duration of the time we discovered how to start and operate it.


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## Juha (Apr 26, 2015)

Koopernic
where you got your quote? The first use of H2S was about one year (Jan 43) after area bombing decision. "Coventry Ordnance Works produced 25% of Britain's aircraft" Really? Lübeck had a port and production connected to U-boats, Rostock had a port and two aircraft factories, Arado's and Heinkel's. Was that so different from e.g. Bristol, which had a port and an a/c factory (Bristol) and was heavily bombed during 40-41 Blitz? Or didn't British have "cultural areas", only Germans? To what are you aiming at?


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## Shortround6 (Apr 26, 2015)

Coventry Ordnance Works made an Airplane?


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## GrauGeist (Apr 26, 2015)

Shortround6 said:


> Coventry Ordnance Works made an Airplane?


Yeah, a biplane during WWI

I didn't know that Coventry Ordnance Works made anything other than Naval guns and mountings during WWII.


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## kool kitty89 (Apr 27, 2015)

pbehn said:


> From what I read when the (accurate) results from the transponders disagreed with the (inaccurate) on the ground reports they believed the false reports, presumed the transponders were not working and stopped using them.


Yes, which is why checking recon results with the transponders against the reports from intelligence agents would potentially expose the nature of the double agents in play. (in spite of the firm insistence that such was impossible)

That would be a far bigger and more valuable revelation than anything regarding accurate reports on V1 bombing impacts.





Koopernic said:


> A Porche design, the 109-005 and a BMW design, the P3006. Both 2 hour life disposable. The 109-005 designer was Max Mueller, who had joined from Heinkel Hirth.
> 
> The *V2* required 280 man-hours to build, maybe 400 with autopilot. A BMW 003 required 700 hours, less than a piston engine, a disposable engine less again. A turbojet powered V1 would not cost much more than a pulse jet V1. German manned jet engine designs were preparing 2 hour life disposal steel turbine blades if they ran out of refractory alloys.


Typo there with the V2, but otherwise very neat. I'd missed wiki's small article on the 005 until now: Porsche 109-005 - Wikipedia, the free encyclopedia
It's notable that thrust output is very similar to that of the much earlier HeS 3, granted the diameter of the latter was much greater at some 930 mm (36.6 inches) slightly smaller and a good deal lighter than the Gnome Rhone 14M. (interesting that the HeS 6 is very close to the 14M's weight and dimensions, at least from the limited information I've seen -considerably smaller than Whittle's designs, though not lighter)

I believe the 004B had managed a bit more than 1/2 the man-hours for construction than the 003's 600~700 hours (around 375 hours -50 of those going to assembly of the final unit).


Heinkel was never focused on producing a cheap, potentially disposable engine though, be it for missiles, expendible aircraft, or conventional aircraft with very high engine replacement rates. (or perhaps even not THAT high of replacement rates, but likely not of the high performance and low frontal areas and weights Heinkel was dreaming of for a cutting edge, record setting high speed fighter -look at the He 100 itself, not so big on compromise for practical applications balancing the raw speed/performance for useful producabality and flexibility -not just the exotic high speed variants, but the fact that no simple/conventional conservative alternatives were implemented in parallel on the early prototypes -like using a completely conventional cooling system)

The HeS 30 was an outstanding design that met or exceeded those lofty aspirations and made the HeS 3 and 6 look extremely poor (and the Jumo 004 not much better) by comparison. Abandoning the experimental but still very workable early designs, hoping for the HeS 30 and then rushing to develop the somewhat hacked together compromise of the HeS 8 as a drop-in replacement on the He 280 airframe conceived around the HeS 30 engine specifications.



> The V1 also known as the Fiesler Fi 103, Kirschkern (Cherrystone, its code name) was to be guided.
> Standard propulsion was the Argus Reed Valve Pulse Jet. Speed was 390mph at low altitude. Improvements in the engine let experimental V1 achieve 515mph at low altitude in Feb 1945


 I'd not heard that at all before, either the higher thrust or higher test speed. Do you have any more specifics? That's the sort of performance gain I'd expect to see with a decent thrust augmentor (or cowling to similar effect -using ram air ducted around the hot section of the engine, deriving energy from the waste heat before being exhausted along with the combustion jet -in practice, a simpler, lighter thrust augmentor attached just aft of the exhaust nozzle is more effective at low speeds, simpler and lighter -the ram effect of a longer sleeve type duct/cowl may be more significant at higher speeds). Sleeve type ducts have the added advantage of working as heat shields around the very hot body/exhaust pipe of pulse jets. (significant for say, underwing mountings)

Simple augmenters can easily increase static thrust by 50%, so a major improvement in acceleration and speed would be likely. (they also tend to dampen vibration, noise, and visible flame) 

I'd thought the Germans overlooked this mechanism, something somewhat surprising and confusing but not impossible. If they had tested alternate nozzle/exhaust, cowl, and ducting configurations, I wonder why they weren't adopted for production. Perhaps the ones they attempted were successful but relatively complex to manufacture? (other relatively simple modifications like flaring the exhaust nozzle significantly improve harmonic combustion stability and ease of starting)

Valveless Pulsejets 1.5 By Bruno Ogorelec
This is a rather fascinating article on the subject, albeit mostly focusing on valveless designs. (including one quite interesting pulse-ram jet hybrid design by Messerschmitt from the early 1970s)





> The disposable turbojet allowed a longer range; increased speed and its lack of vibration did not disturb the guidance system.
> Ewald I guidance couldn't alter the path of the V1 once launched. However a second generation system called *Ewald 2* could.
> 
> There were two terminal homing warheads "Raddischien" or Radish for homing on the allied radar and guidance beacons (tested on a BV246 glide bomb) and MAX-P for homing on to allied microwave systems that might be used in the V1.
> ...


All very interesting, though I still wonder if improved guidance systems could have been developed earlier if the vibration/thrust/fuel consumption limitations of the pulse jet engine hadn't been a constraining factor. (plus development of a reliable, reasonably well performing pulse jet -in practice it's more an art than engineering and involves to this day a lot of trial and error rather than calculated engineering -best option with starting from scratch is to make dozens of prototypes all at once with minor to major differences across the board, some variables even chosen at random to study the behavior ... and then hope the results scale up well) Valve design was probably the most consistent, conventional mechanically engineerable component of the As 014.

Aside from that there's the question of practical use compared to similar area bombing using manned aircraft and not-quite-as-disposible engines. If nearly impossible to intercept, then the losses should be low, and bombing from relatively high altitudes and speeds with mediocre precision targeting is practical for area bombing. (while still being much more accurate than the initial V1 -and possibly operational considerably sooner) The overall cost of resources for manufacturing the expendable engines+missiles and the fuel used compared to bombs+aircraft+engines+pilots (possibly used in a single pilot fighter-bomber-like type configuration) and overall cost of materials expanded per ordinance delivered within the target area. (and desired psychological effect -would the idea of MANNED aircraft managing to invade British airspace yet be impossible to intercept be even more demoralizing? -or at least that logic appealing to German military planners)

Aside from even developing a dedicated bomber ... simply adding provisions for bombs on Heinkel's jet fighter could have been a very appealing prospect. (2500-2600 lbf of thrust from a pair of HeS 6 derived engines, wing/landing gear configured to allow the larger engines ample clearance -AND leave more room under the fuselage for bombs/drop tanks- and enough range to manage the round trip from France to Britain while also useful in fighter-interceptor configuration and in direct competition with Bf 109 and Fw 190 fighter/fighter-bomber development)

Plus, a 4-engine jet bomber could easily have engines in paired nacelles with greater strength for potential shallow dive bombing operations. (or a hypothetical 3 or 4 engine heavy fighter)

I may have to compile these ideas and move them to a separate thread, but I suppose the point here would be:
would cruise missiles be more effective than conventional jet bombers? (particularly given using less strategic materials saves little/not at all on engine manufacturing/assembly costs, only on material costs -and the metals needed for stainless steels used in Heinkel's designs were already being used in heavy quantities in piston engines of the time)





> Area Bombardment, as Arthur Harris plainly explained in his memoir about the targeting bombing of Lubeck, meant that no specific target was chosen, the geometric centre of the city was chosen and destroyed by concentrating in enough bombs, incendiaries in a short enough time to create a fire storm. The true meaning of the terms 'dehousing' and 'demoralisation' should be clear.


Indeed, similar strategies to what RAF Bomber Command had formally adopted under Harris. (targeting material -civil and military, intellectual, and physical/bodily labor forces and infrastructure)


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## GrauGeist (Apr 27, 2015)

The He280 was intended to have the HeS8 as it's powerplants...and the ones tested and demonstrated with the HeS8 performed to all expectations. It was the HeS30 that was supposed to replace the HeS8

The RLM was actually impressed with the He280 and intended to acquire at least 300 units BUT the RLM also got involved with the engine development and insisted on development of the HeS011 instead. It was this meddling that spelled the doom of the He280 as the HeS011 was having serious development problems and cost a great deal of time when the HeS8 was nearly "bug" free and the HeS30 development was coming along behind the HeS8.


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## Koopernic (Apr 27, 2015)

Juha said:


> Koopernic
> where you got your quote? The first use of H2S was about one year (Jan 43) after area bombing decision. "Coventry Ordnance Works produced 25% of Britain's aircraft" Really? Lübeck had a port and production connected to U-boats, Rostock had a port and two aircraft factories, Arado's and Heinkel's. Was that so different from e.g. Bristol, which had a port and an a/c factory (Bristol) and was heavily bombed during 40-41 Blitz? Or didn't British have "cultural areas", only Germans? To what are you aiming at?



Lubeck was a coastal city, so of course it had a port. There was a medium size slipway that repaired Baltic Sea fishing vessels. It sometimes handled repairs to smaller mine sweepers. No U-boats that I know of.

Coventry Ordinance works, I believe the correct statement should be produced parts for 25% of Britain's aircraft.

The first multicavity magnetron that the Germans got their hands on was from a *December 1942* crashed Stirling near Rotterdam. The magnetron was analysed but subsequently bombed and destroyed but by then another had been captured in January 1943. Gee and Oboe (accurate to the radar horizon) were available well before this time.

The point is Lubeck's population was targeted and bombed not the slipway or the Draeger works for medical gases which also did rebreather cartridges for frogmen. the slipway wasn't specifically targeted with the nearby civilians killed as a result of collateral damage due to aiming limitations or a desire to destroy nearby transportation. The civilians themselves were as much if not more the target.

I won't go there, to justification of Area Bombardment, in accepting this policy one goes down the path of over emphasising the kind of equipment that soon precludes any other possible method. It's fine when you can get away with it with impunity but this isn't always the case. The use of orbiting aircraft to relay oboe like signals is a trivial computing problem at a time the coreolis force was factored in to artillery.

Bomber command maintained a list of legitimate targets in cities that were subjected to Area Bombardment as defence against possible war crime charges by its aviators. The only specific criminal act that would be chargeable came under an Artillery officers duty of care under the Hague conventions, he should take care not to hit civilians. Crawling artillery barrages against un evacuated towns were illegal as far as I can see and so one can extrapolate was Area bombardment.

Below a "AWACS" Vickers Wellington which might have been used to use a compass pointed aerial to provide oboe pulse signals transmissions and reception to targets area far greater than the normal radar horizon. The timing pulses would need to be corrected to allow for the movement of the aircraft around a base station but the British electronics engineers were rather good at timing circuits.


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## Koopernic (Apr 27, 2015)

GregP said:


> I was on a team that restored a pulsejet for the Planes of Fame. We had 10 people researching the V-1 not including the 3 team members and we never uncovered a 515 mph V-1 of any sort.
> 
> So, I'd be interested in that if you could point me to a source that I can obtain and study. I see the 390 mph above but wartime production V-1s usually cruised more around 360 - 375 mph as far as we could uncover from German documents.
> 
> If you want to see our results, search Goolge Video for Chino Pulsejet. We also filmed one night run and it is interesting. There was no manual and it took us about a year to figure out how to start it and then another month and a half before we figured out how to get it from idle to full power. We ran it on both 87 Octane unleaded and 100 Octane unleaded. It preferred 87 Octane fuel and ran just fine. 2.2 gallons per minute at idle and 3.3 gallons per minute at full power. We only ran ours untl the internal temperature got to 1,100°F and then shut it off to save the reed pedals. That gave us about a 1.5 minute run while standing still and the temp was down by some 300°F when we ran down the runway at maybe 25 mph. Interestingly enough, the small forward speed combined with the new cowling we made increased thrust by about 25%. We had a thrust measuring setup on the test stand using a spring with a know spring constant and a linear hydraulic cylinder to get the spring compression. We calibrated it to about ±1%. The principle in that restoration was Robin Scott. Bob Velker and I helped Robin for about the last 6 months and all the duration of the time we discovered how to start and operate it.



Speed reached 830kmh (514.6mph) with versions that had both engine and aerodynamic refinements. One probably needs to start thinking about area ruling at 500mph. Without the aerodynamic refinements maybe 780 to 800kmh.

"The A4 (V2) and the German, Soviet and American Rocket Program"
By Claus Reuter

The A4 (V2) and the German, Russian and American Rocket Program by Claus Reuter (eBook) - Lulu
You might try Reuter, Claus Reuter for the author though C Reuter seldom works.

I obtained mine from LuLu books as a downloadble pdf.
Reuter was an engineer with the V1 and V2 program directly involved in developing V1 guidance.

The reason this tome is somewhat obscure is that a/ he is an engineer and the detail is thick at times and b/ he supports the German view point, which comes through. It is an invaluable source. Worth it just for the explanation of how a pulse jet works.

"In 1939 the German Air Ministry decided to have jet engines developed. Each of the German aero-
engine factories was asked to work on different technical solutions of this task. The Argus Motoren
Gesellschaft, Berlin, were asked to develop a pulse jet. Curiously enough, this task was formulated as
follows:

"Take a test tube, put in some drops of gasoline, shake the tube and ignite its open end. The mixture
will not burn continuously, but in rhythmic pulses."
(Don't try at home, use in laboratory environment with PPE)


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## kool kitty89 (Apr 27, 2015)

GregP said:


> If you want to see our results, search Goolge Video for Chino Pulsejet. We also filmed one night run and it is interesting. There was no manual and it took us about a year to figure out how to start it and then another month and a half before we figured out how to get it from idle to full power. We ran it on both 87 Octane unleaded and 100 Octane unleaded. It preferred 87 Octane fuel and ran just fine. 2.2 gallons per minute at idle and 3.3 gallons per minute at full power. We only ran ours untl the internal temperature got to 1,100°F and then shut it off to save the reed pedals. That gave us about a 1.5 minute run while standing still and the temp was down by some 300°F when we ran down the runway at maybe 25 mph. Interestingly enough, the small forward speed combined with the new cowling we made increased thrust by about 25%. We had a thrust measuring setup on the test stand using a spring with a know spring constant and a linear hydraulic cylinder to get the spring compression. We calibrated it to about ±1%. The principle in that restoration was Robin Scott. Bob Velker and I helped Robin for about the last 6 months and all the duration of the time we discovered how to start and operate it.


Neat! I'd seen the Chino pulse jet demonstrations before, but hadn't realized the nature of the cowling. 

This video in particular shows it well: 
_View: https://www.youtube.com/watch?v=WCsKs2NhdWg_ 
It appears to be similar to typical NACA cowlings used on radial engines.

Any idea if propane was tried during early test-start-ups? (liquid fuel starting can be really problematic ... propane seems to be the go-to fuel for easy starting and test-runs before things are smoothed out -or as a starting fuel, and MUCH safer than the acetylene Germans used)

The paler flame (and slightly bluish tinged orange flame in the night video) seems to point towards leaner/more complete combustion than a lot of other V-1 tests and similarly sized pulse jet designs.


Aside from that, I do wonder if using an even longer cowling that shrouds the entire exhaust pipe (or particularly one extending beyond the exhaust nozzle -acting a venturi to draw air through the cowl/duct even when static) would be even more effective in improving thrust.

I mused on it in much greater detail in my previous post, but seeing the Chino jet in action, I can pretty easily say the concept is basically that sort of cowl combined with the simple thrust augmentor explained here: 
_View: https://www.youtube.com/watch?v=Ab5DU15O9s8_ 
This design seems to use a cowl/duct extending all the way to the exhaust nozzle, but it ends short of the exhaust nozzle itself. I'm not entirely sure why.

In fact, I'm now wondering if the As 044 wasn't just a scaled up 014, but derived its added thrust from improved cowling/ducting design instead. (which implies superior fuel consumption as well) And perhaps it's the 044 that was tested on the faster V-1 variant?





It's interesting to note (and I only just discovered this when searching for some of these relevant pulse jet articles that Boeing is currently developing an embedded cowl/duct augmented valveless pulse jet engine rather seriously.

_View: https://www.youtube.com/watch?v=chmmUF9fPSE_

Not sure if there's any particular recent advancements that favor this, the basic concept (with or without valves) seems kind of obvious to at least experiment with. If that video's accurate, they also seem to be using the cup type valveless arrangement (I'd have thought the pulse/ram jet transition arrangement would be preferable -also has merits when used purely for pulse configuration, but I'm sure they have reasons -I assume Messerschmitt's patents on that type would have long since lapsed at this point too).


On the general topic of pulse jet efficiency:

_View: https://www.youtube.com/watch?v=b0KJwa5iWTY_


_View: https://www.youtube.com/watch?v=rbn8qvjjAW4_

Though a lot of the hobby jets are simplified by using propane as fuel, or easily vaporizing and smokeless fuels like methanol. (or sometimes methanol/nitromethane blends, similar to small two-stroke glow-plug engines)






GrauGeist said:


> The He280 was intended to have the HeS8 as it's powerplants...and the ones tested and demonstrated with the HeS8 performed to all expectations. It was the HeS30 that was supposed to replace the HeS8


See my reply here: http://www.ww2aircraft.net/forum/av...s-ww2-jets-39511-post1200914.html#post1200914


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## Koopernic (Apr 27, 2015)

The Anthony Kay book on German Jet engines provides some information on inductor ramjets which could achieve a static thrust. The liquid fuel was heated to high pressure and injected by a nozzle, this induced airflow which brought in air. At some point you used the ramjet tube itself to heat heat the fuel. It was rather hard to control the temperature of the fuel. Propane as a fuel made sense in that the V1 used compressed air to pressurise the main fuel tank and to blow fuel into the engine. Why not used propane, which was available as a by-product of the synthetic oil plants. Compressed air was used to spin the gyros of the V1's guidance system as well as operate its flight surfaces. If there was a battery needed, it provided minimal power.


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## Juha (Apr 27, 2015)

Koopernic said:


> Lubeck was a coastal city, so of course it had a port. There was a medium size slipway that repaired Baltic Sea fishing vessels. It sometimes handled repairs to smaller mine sweepers. No U-boats that I know of.
> 
> Coventry Ordinance works, I believe the correct statement should be produced parts for 25% of Britain's aircraft.



In fact I doubt even that, IMHO COW during WWII produced mostly large gun turret mountings for the navy, too heavy stuff for a/c.



Koopernic said:


> The first multicavity magnetron that the Germans got their hands on was from a *December 1942* crashed Stirling near Rotterdam. The magnetron was analysed but subsequently bombed and destroyed but by then another had been captured in January 1943. Gee and Oboe (accurate to the radar horizon) were available well before this time.



AFIK the Rotterdam Gerat (H2S ground-mapping radar)was salvaged from a Stirling which crashed near Rotterdam on 2 Feb 43



Koopernic said:


> The point is Lubeck's population was targeted and bombed not the slipway or the Draeger works for medical gases which also did rebreather cartridges for frogmen. the slipway wasn't specifically targeted with the nearby civilians killed as a result of collateral damage due to aiming limitations or a desire to destroy nearby transportation. The civilians themselves were as much if not more the target.



Was that in practice much different from targeting Bristol harbour, which didn't have any strategic significance in 40s (Avonmouth and Portishead had, but they were seen as separate targets by the LW), which was straight in the middle of a historical city, surely a "cultural area" if Bristol would have been a German city. In fact the 4 first Blitz raids against Bristol killed 600 civilians, the 4 raids against Rostock killed 204. In Lübeck 312 or 320 died, the highest casualty figure for the first four Bristol raids was 200.




Koopernic said:


> Bomber command maintained a list of legitimate targets in cities that were subjected to Area Bombardment as defence against possible war crime charges by its aviators.



How it was that British thought that the LW used the same ruse during 40-41 Blitz





Koopernic said:


> Below a "AWACS" Vickers Wellington which might have been used to use a compass pointed aerial to provide oboe pulse signals transmissions and reception to targets area far greater than the normal radar horizon. The timing pulses would need to be corrected to allow for the movement of the aircraft around a base station but the British electronics engineers were rather good at timing circuits.



IIRC AWACS Wimpys were used in 1945, a bit later than Lübeck and Rostock attacks


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## stona (Apr 27, 2015)

There's some serious BS regarding bombing above. The British did target cities and not specific targets in area raids. Harris is on record as saying acreage destroyed was more important than individual factories etc.

The German raids of the Coventry type were also area raids, attempts to burn the city rather than destroy specific targets, whatever they may have produced. The crucial clue is in the make up of the ordnance dropped by the bombers. A high percentage of incendiary almost always equated to an area raid (or area type raid as the USAAF coyly called them)

The reason that the Luftwaffe did not create a firestorm, which is a particular physical phenomenon, is because they only managed one of the two most important criteria to achieve this. Bombing has to be concentrated in space and time. The Luftwaffe could certainly concentrate their bombing in space but they were 'shuttle bombing'. The aircraft employed carried relatively light loads and returned to bases in France to re-arm before returning. The bombing of Coventry took hours. By contrast the initial 5 Group raid on Dresden, which created the firestorm, took only 25 minutes to drop 881 tons of ordnance (43% by weight incendiary)
It was not for want of trying that the Luftwaffe failed to create the kind of devastation Bomber Command later would. It was for lack of suitable aircraft and enough of them.

The first loss of a Gee equipped aircraft was 12/13 August 1941 when one of the trial Wellingtons was lost over Hannover. This was seriously bad luck as the first trial had only been on the previous night. The first raid generally considered to be the first 'Gee led' raid was that on Cologne on 13/14 March 1942.

First operational trial of Oboe was a raid on Brest on 7/8 December 1941. Stirlings of Nos. 7 and 15 Squadrons carried the new system. I don't know when the first set was lost.

Cheers

Steve


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## pbehn (Apr 27, 2015)

kool kitty89 said:


> Yes, which is why checking recon results with the transponders against the reports from intelligence agents would potentially expose the nature of the double agents in play. (in spite of the firm insistence that such was impossible)
> 
> That would be a far bigger and more valuable revelation than anything regarding accurate reports on V1 bombing impacts.



That is correct except that whenever any investigation was performed the Germans preferred not to believe the unbelievable, enigma couldnt be broken and so it wasnt and all german agents couldnt be turned so they werent. In terms of all the evidence going one way a few bomb craters would not prove or dis prove anything. The Germans had ample evidence that their codes were being broken and that their agents had been turned, they chose to ignore all of it.
To me the only possible effect on the war the V1 could have had would be bombarding the beachhead at Normandy. Reading here the intense activity being done to launch V1s from Aircraft as the allies were overrunning the launch sites shows a sort of collective detachment from reality.


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## GregP (Apr 27, 2015)

Hi KoolKitty,

If they made the missile a lot larger, it would then be about the size of a manned aircraft. That would mean it would probably slow down unless it was very carefully designed and powered. The faster piston planes were using a Daimler-Benz engine (or radial) that cost an order of magnitude more to produce than a pulsejet. So ... while the guidance options might have been more, I doubt: 1) they could have afforded the 1-way engines and 2) that the number "new larger V-1s" that got through would be nearly as many as the smaller, faster, real V-1s that really did get through.

I have never yet seen a "what if" that could be answered to the satisfaction of most. It's probably better to deal with the real V-1 and investigate alternative electronics than to redesign the missile. However, you'd have to know what was available and when to make an eductaed alternative proposition. I'm an electrical engineer and I know the technology, but not exactly when it was made available since it was all there when I started college (in a different discipline to start with) as well as a host of digital devices that would have been great for the WWII purposes but weren't yet invented during WWII.

Going back to when we restored a pulsejet, the breadth of what they knew was impressive, but we weren't really sure exactly what was available to them ... all we got the was design documents of what they actually produced. Those documents did not include alternative guidance solutions from the time. So I think that without detailed knowldge of exactly what techologies they had it would be extremely difficult to second-guess the German engineers of the time ... at least for me to do it.

We know they had no GPS and no digital devices. They DID use a vane amemometer (the little prop on the fornt) to measure time / distance. I'm thinking, but not concluding, that they did the best they could with what they had at the time. I'm not too sure how it could have been made more accurate simulaneously with still being autonomous.

With all the fighters patroling and shooting down all the V-1s they could, I'd think a pathfinder plane to drop transmitters would have had a very low survival probability, but I could be wrong there. I'd hate to try to punch through the lines of defending Spitfires, Tempests, and Typhoons, P-51s, etc. that were intent on shooting down V-1s. If the pathfinder didn't make it, then the surviving V-1s would ALL miss or would revert to the existing guidance system. If they all missed it would be a monumental waste for Germany and if they used the default guidance, then who would volunteer to commit virtual suicide to make them slightly more accurate?

So I'll decline to speculate what they might have done better. I really like that fact that they managed to get it to fly a dogleg to try and hide the lunch site. That alone says a lot about the clever thinking that went into the V-1.

So, you might be right above, but I won't try to conclude anything about alternative V-1 designs. If I had to design one now, it would be a lot better, but I have a few years of technology from which to draw that they didn't have. Even brushless servo motors would have been a big step forward.


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## tyrodtom (Apr 27, 2015)

We seem to be concentrating on the higher speed of the V1s making them harder to intercept by aircraft. 
I've got to agree on that.
But weren't most of the V1s brought down, destroyed by antiaircraft fire ?
How much difference would the extra speed mean to the effectiveness of the proximity fuses of the AA ?

But did the Germans know what was bringing down most of their V1s ?


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## GregP (Apr 27, 2015)

Hi Again KoolKitty,

The cowling was designed by the guys on our team and we had it made using metal spinning technique and riveted it together to form the round cowl behind the round front lip. We made a wood mold and the metal spinner spun it on a lathe out of Aluminum. We polished the front lip for a better look, but painted the rest. It faded from heat. Should have used header paint.

The fuel we used was exclusively gasloine. We ran 87 Octane and 100 Octane, both unleaded. After we discovered how to start it (6 months or slightly more), it ran well. We had to use a bypass valve to bypass the fuel regulator for startup since we were using about 90 psig of compressed air to get it going at idle power and that would blow out the rubber diaphragm. We constructed a mold and molded 4 rubber diapragms ... we blew out 2 of them learning to start it.

We were at a standstill when we decided to approach the engine while it was running and try to push the fuel metering level down by hand. The tube got seriously hot and the convective heat was terrific, but we learned how to get the engine to full power by hand. We then made a friction stop controlled by a wing nut and we could get the engine from idle to full pwoer and then tighten down the nut to hold the full power setting, shut off the compressed air. When we did, the fuel metering regulator operated as designed and maintained the fuel pressure at a constant level, resulting in good, solid, full-power runs.

Later, we added an electric solenoid and used a potentiometer to regulate the current through it, and we could operate the fuel metering lever remotely. After than, it got easier each time we ran it until the fuel pump starting flucuating. Now the fuel pump needs a rebuild. When we stopped running it, we were getting erratic runs due to erratic fuel pump operation.

The museum got a lot of noise complaints every time we ran it, so it is sitting right now, waiting for a fuel pump rebuild, but with little official interest in continuing to operate it. Therefore it is somewhat of a display item at this point. We COULD start it, but the fuel pump just isn't quite right and it souldn't be my first inclination to operate with a known fault. We have a dearth of spare parts, so it we break anything, it might be all over ... we DO have ONE spare set of reed petals, but all of us who restored it want the fuel pump rebuilt before we run it again and are not going to fund it any further from our own pockets. We already have several thousand dollars of our own money in it but it belongs to the Museum. We think it would easily pay for itself at shows but I MUST admit, it is LOUD. You can probably hear it for 5 miles or more when it is at full power, and low frequencies carry a LONG way.

The first time we got it to full power we had three fire departments and two Police cars respond to see what was continuously blowing up for so long! After that, we called the tower to let them know if we were going to run it.


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## tomo pauk (Apr 28, 2015)

tyrodtom said:


> We seem to be concentrating on the higher speed of the V1s making them harder to intercept by aircraft.
> I've got to agree on that.
> But weren't most of the V1s brought down, destroyed by antiaircraft fire ?
> How much difference would the extra speed mean to the effectiveness of the proximity fuses of the AA ?
> ...



Greater speed will mean less shells fired on the missile. Faster target is also harder to hit, or to make a near miss that will make the proximity fuse to detonate. Cumulative effect of greater speed should be a greater survivability of missile.


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## pbehn (Apr 28, 2015)

From what I read the radar gun laying and proximity fuse took an increasing toll on V1s as they were deployed. From a theoretical point of view, if the guidance is 100% effective and the launch site is known it makes interception with artillery and barrage balloons easier.


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## Juha (Apr 28, 2015)

On V-1 all I can say is that according to the British their speed varied between 300 - 420 mph, avarage speed was 350 mph (480 - 675 km/h, 563 km/h) and flight altitude from tree-tops to 8,000 ft. Source The Blitz Then and Now. IIRC the British thought that the variations were results of indifferent production quality, after all V-1 was a low-price product.


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## GrauGeist (Apr 28, 2015)

pbehn said:


> ...it makes interception with artillery and barrage balloons easier.


The V1 had cable-cutters on their wings, so they could evade balloons for the most part, although about 300 V1s were successfully brought down.

A suggestion about the varying speeds reported for the V1: as time wore on, the different manufacturers were making the V1 from various materials, wouldn't this effect airspeed? Some V1s had steel skinned wings, some had plywood and others had aluminium. There was also quality control on the engines themselves...these were manufactured by forced labor, after all.


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## FLYBOYJ (Apr 28, 2015)

Juha said:


> after all V-1 was a low-price product.



Again, that should be the emphasis of this thread. COST

I did a little research and I welcome anyone to correct my numbers.

Just before WW2 one US dollar equaled 2.49RM

The V-1 according to Wiki cost 5090 RM which equals $2044 US dollars during WW2, roughly $34,700 in todays dollars.

The Jumo 004 cost 10,000RM, roughly $4010 US dollars during WW2, $68,200 in today's dollars.

So here you had a complete weapon system, the V-1 which cost almost half of a turbine engine of the same period. 

Do the math.

Reactions: Like Like:
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## Koopernic (Apr 28, 2015)

FLYBOYJ said:


> Again, that should be the emphasis of this thread. COST
> 
> So here you had a complete weapon system, the V-1 which cost almost half of a turbine engine of the same period.
> 
> Do the math.



The man hours for a Jumo 004 and BMW 003 are well known and indeed they are approximately twice that of the V1.

There wasn't likely an exchange market of $US versus RM in 1944 so its hard to tell. One could probably tell from how neutrals such as Spain, Turkey, Portugal valued RM versus $US. I recall figures between 4.2 (when it was set by the German Government in 1936) and 10, suggested late war.

If one assumes a modern low end wage for manufacturing of $40/hour the 800 hour jumo is about $32000 and the V1 about $16000. Which double checks your figures.

I think the costs might have gone down lower still as automation came in: presses, jigs, large assemblies made in one operation.

From Elegance in Flight:






I'd be surprised if there were that many man hours in engines such as the Merlin or DB605 but one would have to only take the costs of the most advanced piston engines.


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## FLYBOYJ (Apr 28, 2015)

Koopernic said:


> The man hours for a Jumo 004 and BMW 003 are well known and indeed they are approximately twice that of the V1.
> 
> There wasn't likely an exchange market of $US versus RM in 1944 so its hard to tell. One could probably tell from how neutrals such as Spain, Turkey, Portugal valued RM versus $US. I recall figures between 4.2 (when it was set by the German Government in 1936) and 10, suggested late war.
> 
> ...



My source for the exchange rate, 1938

Historical US Dollars to German Marks currency conversion

My point is you have one V-1 complete for at least half the cost of just one turbo jet engine.

Now having built both aircraft engines and airframes, there's only so much you're going to automate or reduce manufacturing steps, especially looking at 1940s technology. BTW, the 5090 RM cost of the V-1 was from wiki as the indicated cost of the Jumo; I'm assuming those are out the door figures


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## pbehn (Apr 28, 2015)

It helps when you have access to slave labour, I believe the V weapons cost as many lives on the German side as they did on the allied side.


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## FLYBOYJ (Apr 28, 2015)

pbehn said:


> It helps when you have access to slave labour, I believe the V weapons cost as many lives on the German side as they did on the allied side.



One could only guess where slave labor factors into those numbers


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## kool kitty89 (Apr 29, 2015)

GregP said:


> If they made the missile a lot larger, it would then be about the size of a manned aircraft. That would mean it would probably slow down unless it was very carefully designed and powered. The faster piston planes were using a Daimler-Benz engine (or radial) that cost an order of magnitude more to produce than a pulsejet. So ... while the guidance options might have been more, I doubt: 1) they could have afforded the 1-way engines and 2) that the number "new larger V-1s" that got through would be nearly as many as the smaller, faster, real V-1s that really did get through.


I was speculating on using a more powerful engine ... a throw-away turbojet specifically, possibly in the 1,000-1,100 lbf class like the 1938/39 HeS 3. (the idea being something considerably cheaper than the 004B, available much earlier, while being more powerful than the As 014, vibration-free, and much more fuel efficient)

Granted, you could still argue for speed (or speed+range+altitude+much earlier service date) over any increase in guidance system complexity or payload. The overall cost would still be less than double that of the existing V1, so the question is whether it would be at least twice as effective ... or worth the earlier service entry. (lack of vibration issues would speed up development of the existing system dramatically if nothing else)

Beyond that, I'm less sure whether cruise missiles would be more economical than jet powered bombers using longer-life versions of similar engines. (particularly early/mid war when there was less of a pilot shortage)








GregP said:


> The museum got a lot of noise complaints every time we ran it, so it is sitting right now, waiting for a fuel pump rebuild, but with little official interest in continuing to operate it. Therefore it is somewhat of a display item at this point. We COULD start it, but the fuel pump just isn't quite right and it souldn't be my first inclination to operate with a known fault. We have a dearth of spare parts, so it we break anything, it might be all over ... we DO have ONE spare set of reed petals, but all of us who restored it want the fuel pump rebuilt before we run it again and are not going to fund it any further from our own pockets. We already have several thousand dollars of our own money in it but it belongs to the Museum. We think it would easily pay for itself at shows but I MUST admit, it is LOUD. You can probably hear it for 5 miles or more when it is at full power, and low frequencies carry a LONG way.
> 
> The first time we got it to full power we had three fire departments and two Police cars respond to see what was continuously blowing up for so long! After that, we called the tower to let them know if we were going to run it.


I think I recall seeing a video from one of the early start-up attempts and the fire department showing up to check on things, though this may have been some other folks.
Ah, nope, it was another group with that appears to be an original As 014 and custom rebuilt valve grid by the sound of the conversation around half way in. They also mention using 50/50 gasoline and diesel fuel (seems like that'd be harder to start on) and a supercharger to supply the compressed air.

youtube.com/watch?v=jTsQxwWcqJI


With the Chino jet, I wonder if you guys could set up some kind of muffler to dampen the sound on test runs. Maybe rig up a 55 gallon drum with the bottom cut out and a bunch of holes or slots punched in it placed at or near the exhaust outlet. (without the perforations, the drum might still muffle things somewhat, but also end up acting as a crude thrust augmentor, which would wouldn't be the intended purpose and could have ... interesting results depending how the drum/muffler rig was mounted)


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## kool kitty89 (Apr 29, 2015)

Koopernic said:


> The Anthony Kay book on German Jet engines provides some information on inductor ramjets which could achieve a static thrust. The liquid fuel was heated to high pressure and injected by a nozzle, this induced airflow which brought in air. At some point you used the ramjet tube itself to heat heat the fuel. It was rather hard to control the temperature of the fuel.


Pulse combustion does away with those problems with heating ... at least once they've warmed up to minimum operating temperature (or use a fuel that lowers the min operating temp) and would almost certainly produce more static thrust at far better specific fuel consumption than a ram jet using the venturi effect for continuous static combustion. (I'd imagine the latter would be closer to the limited thrust resulting from a blow lamp or blow torch -though having ANY sort of stable flame /and/ thrust at static speeds is significant for a ram jet) 

That said, that idea of using a pressurized heated fuel jet inside a RAM jet is very much relevant in the idea of placing an entire pulse jet inside a RAM duct sleeve (effectively acting as the combustion chamber embedded inside a ram jet). Be it a valved or valveless design, a cowl/duct with a ram inlet adding significant compression at high speeds would force the pulsing combustion into continuous flow combustion (due to pressure forcing the shutters to remain open in the valved examples -the valve grid acting as flam holders for the combustion chamber).

On the note of ram jets, those would also avoid the issues related to vibrations and have better altitude performance compared to pulse jets, but they'd need to be able to reach a critical airspeed/thrust threshold with catapult/rocket assist. (or air-launched in an accelerating dive, or some combination of those)




> Propane as a fuel made sense in that the V1 used compressed air to pressurise the main fuel tank and to blow fuel into the engine. Why not used propane, which was available as a by-product of the synthetic oil plants. Compressed air was used to spin the gyros of the V1's guidance system as well as operate its flight surfaces. If there was a battery needed, it provided minimal power.


Propane needs fairly heavy pressure tanks to be liquified and is a fair bit less dense than gasoline even as a liquid (though better volumetric energy density than methanol by a good margin). Butane or a propane-butane blend, or some economical cocktail of LPGs with relatively low liquification pressures would make sense, though. (same would apply to a turbojet using a pressure feed)

For that matter, you could potentially use fuel bleed to power the pneumatic instruments rather than compressed nitrogen, possibly vented into an intermediate medium pressure gaseous expansion tube/chamber/regulator fed into the fuel jets rather than just vented. (though the temperature drop from liquid to gas phase shift might make the LPG gas too cold to properly operate some of the instruments, or lead to icing, and while I've seen regenerative cooling used for butane vaporization on model pulse jets, and that too would be useful here -for combustion needs- having fuel piped to the hot section and then BACK to the instrumentation seems inefficient/needlessly complex when the solution is to use an independent local nitrogen chamber)




Koopernic said:


> The man hours for a Jumo 004 and BMW 003 are well known and indeed they are approximately twice that of the V1.


I've seen some figures (or at least claims) putting the 004B at 375 man hours to the 003's 600, but I'm not sure how accurate those are or what the context was. (differing production lines, volumes, workforce, among other factors)

Something like the HeS 3 should take considerably less time/cost though, particularly if further developed/modified specifically as a cheap/short life engine.

But aside from that the bigger point wouldn't be whether an alternate cruise missile was more or less expensive to build than the V1, but the relative effectiveness ... the bang for buck. That and whether a (basic) turbojet design could have reached service earlier.

On that note, using LPG fuel would actually ease/solve some of the problems with the HeS 3 design, including the reliance on starting on hydrogen for a warm-up period until the kerosene vaporizer tubing reached operational temperatures. (plus pressurized gaseous fuel avoids the complexity of a fuel pump and use on a disposible missile avoids the concerns with vulnerable pressure tanks compromising a piloted combat aircraft)
Due to the ease of synthesizing it from methanol and smokeless flame even during incomplete combustion, dimethyl ether might be an attractive fuel to target in particular. 

According to:
F3 Centre
Dimethyl ether has 70% of the energy content per volume (as a liquid) of conventional diesel fuel, or roughly 80% that of gasoline by volume, compared to 74% for propane based on: Gasoline gallon equivalent - Wikipedia, the free encyclopedia

DME would have similar advantages for use on pulse jets with lack of smoke/soot and ease of start-up. (advantages for use in ram jets too)





pbehn said:


> From what I read the radar gun laying and proximity fuse took an increasing toll on V1s as they were deployed. From a theoretical point of view, if the guidance is 100% effective and the launch site is known it makes interception with artillery and barrage balloons easier.





tyrodtom said:


> We seem to be concentrating on the higher speed of the V1s making them harder to intercept by aircraft.
> I've got to agree on that.
> But weren't most of the V1s brought down, destroyed by antiaircraft fire ?
> How much difference would the extra speed mean to the effectiveness of the proximity fuses of the AA ?
> ...


Ignoring the V1 production cost and target hitting precision, the ability to fly faster AND at higher altitudes than the existing V1 would have been very significant for AA evasion. The low altitude flights of the existing V1s meant great vulnerability to light and medium as well as heavy AA (where proximity fuzed shells would come into play). An increase in speed AND altitude would dramatically improve AA resistance though, and in the case of a turbojet, the exhaust jet would be invisible (or nearly so) and noise levels drastically lower. (not that that would matter for radar sighting)

Come to think of it, though, I wonder if some V1s were picked up on the old acoustic mirror system before they showed up on RADAR, particularly any that flew very close to wave/treetop level, flying under the radar.


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## tyrodtom (Apr 29, 2015)

I disagree that flying higher would make the V1s less resistant to AA.
The heavy AA was radar guided, and equipped with proximity fuses.
A radar directed gun has no more problem determining lead for a 550mph target than it does for a 350mph target, and by flying at higher altitude, you give each individual gun more time to shoot at you horizon to horizon, though increaseing the speed would decrease that time of course. But increasing speed while increasing altitude at the same time might end up not decreasing time exposed to each AA weapon site.

If they wanted to make it impossible to shoot down , they should have made it fly faster and lower. Too fast for the fighters to intercept, and by the AA gun crews before they could alert them, or even traverse a gun if they were alert.
That's the way modern cruise missiles do it, fast and very low.


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## FLYBOYJ (Apr 29, 2015)

kool kitty89 said:


> I've seen some figures (or at least claims) putting the 004B at 375 man hours to the 003's 600, but I'm not sure how accurate those are or what the context was. (differing production lines, volumes, workforce, among other factors)
> 
> Something like the HeS 3 should take considerably less time/cost though, particularly if further developed/modified specifically as a cheap/short life engine.
> 
> But aside from that the bigger point wouldn't be whether an alternate cruise missile was more or less expensive to build than the V1, but the relative effectiveness ... the bang for buck. That and whether a (basic) turbojet design could have reached service earlier.




The man hour numbers are just that. You could factor that at a normal labor rate of consider the free "slave labor" that was available. You have to consider the cost of material, but regardless the sources at Wiki are showing that a complete V-1 airframe is nearly half the cost of a Jumo engine alone. Throw in the rudimentary guidance systems of the day and I see no way you could get "more bang for the buck" with what was available at the time. The V-1 was cost effective and IMO if introduced earlier in the war "would have" been more of a game changer than an earlier deployment of the Me 262.


tyrodtom said:


> I disagree that flying higher would make the V1s less resistant to AA.
> The heavy AA was radar guided, and equipped with proximity fuses.
> A radar directed gun has no more problem determining lead for a 550mph target than it does for a 350mph target, and by flying at higher altitude, you give each individual gun more time to shoot at you horizon to horizon, though increaseing the speed would decrease that time of course. But increasing speed while increasing altitude at the same time might end up not decreasing time exposed to each AA weapon site.
> 
> If they wanted to make it impossible to shoot down , *they should have made it fly faster and lower. Too fast for the fighters to intercept, and by the AA gun crews before they could alert them, or even traverse a gun if they were alert.* That's the way modern cruise missiles do it, fast and very low.



Exactly!!!


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## Koopernic (Apr 29, 2015)

tyrodtom said:


> We seem to be concentrating on the higher speed of the V1s making them harder to intercept by aircraft.
> I've got to agree on that.
> But weren't most of the V1s brought down, destroyed by antiaircraft fire ?
> How much difference would the extra speed mean to the effectiveness of the proximity fuses of the AA ?
> ...



The claim is that at their peak effectiveness SCR-584 radar directed guns firing radio proximity fused shells got down to 40 rounds per V1 destroyed.

V1’s which increased speed from 600kmh to 650kmh do seem to have reached the front. Those that achieved 760km/h due to engine improvements and 815kmh due to a combination of improvements didn’t. After testing something in a R+D section one has to check and issue production drawings, set up production, introduce new user instructions.

I've tried to do a calculation on decreased vulnerabillity. A V1 at 375mph would be moving at 170m/s, at 440mph at 200m/s and 515mph at 235m/s.
It would cover 1.6km or 1 mile in 9.5 sec, 8 sec and 6.5 seconds respectively.

Assuming shooting begins at 3.25 miles range (5.5km) and ceases at 0.25 (400m) there will be 28.5 seconds, 24.0 seconds or 19.5 seconds to shoot during which a battery of 6 (I’m assuming the US 90mm M3 and UK 34 pounder were in 6’s) could fire a round every 2 seconds per gun (very generous, assuming VT fuzes and auto loader) hence there would be 14.25 rounds, 12 rounds and 9.75 rounds fired from 1 gun at a lone V1.

To summarise, if firing commences at 3.25miles and ceases at 0.25miles then for a single gun:
1 605kmh/375mph,170m/sec means 14.25 rounds can be fired over 28.5 seconds, increasing to 84 rounds if a battery of 6 AAA is available.
2 715kmh/440mph,200m/sec means 12.0 rounds can be fired over 24 seconds, increasing to 72 rounds if a battery of 6 AAA is available.
3 830kmh/515mph,235m/sec means 9.75 rounds can be fired over 19.5 seconds, increasing to 58 rounds if a battery of 6 AAA is available.


For a centrally directed battery of 6 guns there would be 84, 72, 58 rounds which generally is just enough to deal with a V1. I would assume that 40mm bofors would be placed in between, generally the most effective AAA gun of WW2. The 20mm gun would tend to be too short ranged, while the heavy guns cannot traverse fast enough to follow the V2 when it is directly overhead.

V1’s were initially intended to cruise at 9000ft however a nagging problem with the autopilots barometric capsule forced them down to 3000ft. V1's may have changed tactics to higher altitude or more extreme low altitude.

However if two V1’s can be launched simultaneously so that they cross the same area of coastline at the same time the second one may not even be engaged. Just as a lone B-17 or Lancaster can not survive over the Reich a lone V1 is also more vulnerable.

1 The higher the speed the less rounds can be fired and the less subsequent targets engaged for a firing cycle. 2 Any measurement error in the radar, FLAK predictor, gun laying, gun and optics alignment and barrel is amplified by the greater speed of the missile. These two effects would compound. For instance miscalculate the speed of a 650kmh V1 by 5% 2 seconds ballistic flight time away and you might miss by 17m, If it is a 815kmh missile you miss by 22.5m.

Other factors would be the time interval between completion of a engagement of a target and the time to re-engage a second one.

Of course if the V2 was being engaged by a highly effective modern system, such as Phalanx or a modern naval gun, the calculation would be moot. It would be gone if not in the first round then as soon as the radar had measured the miss of the first of the previous rounds and corrected.

Given the state of the art and the supposed requirements of around 40 rounds I'm hazarding to say that a 20% increase in speed would lead to at least a reduction of V1 kills from 0.8 x 0.8 = 64% reduction in effectiveness of the system. I think it would be worse in fact.

The cost of the 40 proximity fused rounds in money and material terms would be quite hefty.

Of course this is non linear. If the Germans can either saturate British AAA defences in a small area (which is what bomber command did to German defences) or disperse their attack so that coastal areas not covered by FLAK batteries are overflown the situation changes. 

The German aviation industry had approximately 2 million involved in WW2, assuming this is really 1 million and that they dedicate 5% of it to V1 production they have 50,000 people would could in theory produce 5000 V1s per week (20,000 per month) if each cost 400 man hours which would be 666 per day. V2 production was to reach 1000 and then step up to 4000-5000 month.

Some on the German side were considering not 1000 or 5000 month but 100,0000.

Even assuming that only 20% of V1's reach metropolitan towns, mainly London this suggests that of 20,000 V1 launches per month 4000 might hit part of a city: it could be a house, a factory, a barracks, a church, a street car, a busy road, a school with or without children, a farmers field, a block of apartments, an airfield. Exactly the same as Area Bombardment did though without the possibility of a firestorm. Somewhat mercifully engine noise and then the cut out of the engine gave a good warning.

It doesn't matter that if of the 20000 launches only 20% hit a structure, only that 4000 did and that the cost was affordable. Four engine bombers had similarly discouraging results.

It's said that a V1, if it hit a farmers potato field, was so cost effective the value of the potatoes to the British economy exceeded that of the V1.

The successful allied invasion restricted V1 launch sites allowed allied defences to be concentrated. The difficulties the Germans had due to the invasion reduced the German launch rate and thus prevented the possibility of saturation of Allied defences.

"If" 100 V1 launch sites (I believe 76 were operational) could launch 7 missiles in 7 minutes then 700 V1's could be crossing the UK coast within 10-17 minutes of launch. Catapults were nowhere near capable of that.

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## tyrodtom (Apr 29, 2015)

No doubt 2 V1 could be launched at the same time, but with their big quality control problems, would those same two V1 assume accurate enough flight paths to go over the same piece of real estate at the same time 75-100 miles away ?


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## Koopernic (Apr 29, 2015)

The V1 used a barometric altimeter, how low could one make such a device work reliably? Maybe 100ft?


If one wanted to go lower then the FuG 101a FM radar altimeter will go down to about 2m. They were used as part of blind landing systems and to help German bombers penetrate at night.



tyrodtom said:


> No doubt 2 V1 could be launched at the same time, but with their big quality control problems, would those same two V1 assume accurate enough flight paths to go over the same piece of real estate at the same time 75-100 miles away ?



I would think one would have to just rely on launching many V1 from as many locations as rapidly as possible. The limitations of the AAA belts would be not number of guns but the number of SCR-584 radars and M9 directors. (which had analogue outputs for the US 90mm and selsyns form the British guns) As the allies broke out from Normandy (Operation Cobra) the Germans lost their launch locations and the ones they had gave very limited flight optons that allowed AAA defences to be built.

The EWALD 2 guided versions were intended to lead up to 4 closely trailing versions of the V1. I believe they were to use "blitzubertragung": basically "flash transmission" like in an xenon electronic camera flash to home on to, according to Fritz Trenkle's book on German WW2 missile guidance. (German Only). It may have been code named Moselle (after the river)


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## Milosh (Apr 29, 2015)

The manual states an accuracy of +/- 10% and states that 0 and 3 meter height are clearly distinguishable.

In practice the system worked pretty well over solid ground and water. When flying over woods, the signal would show variations.

The question is could the FuG react quick enough at low altitude to a sudden increase in elevation over tree covered terrain?


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## stona (Apr 29, 2015)

Koopernic said:


> If one wanted to go lower then the FuG 101a FM radar altimeter will go down to about 2m. They were used as part of blind landing systems and to help German bombers penetrate at night.



And add even more expensive equipment, and impose another demand on limited resources for a throwaway weapon? What could the justification be for this? 

The FuG 101 also required a relatively bulky power supply to go with the receiver and transmitter units. The two antennae would be the least of the problems, though there were limits (which I can't remember) to their separation.
The system also had two altitude ranges, basically depending in which direction the motor responsible for the frequency modulation was running. In an aircraft the range (0-150 or 0-750 ) metres could be selected by a human. The speed of that motor also had to be tuned manually as it could vary with the voltage from the on board PSU. It was typically calibrated to 60m. None of this would be possible in an unmanned aircraft like an upgraded V-1. 

Cheers

Steve


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## GrauGeist (Apr 29, 2015)

Koopernic said:


> V1’s which increased speed from 600kmh to 650kmh do seem to have reached the front. Those that achieved *760km/h due to engine improvements* and *815kmh due to a combination of improvements* didn’t. After testing something in a R+D section one has to check and issue production drawings, set up production, introduce new user instructions.


I keep seeing these figures and am wondering where they come from...

The V1, as powered by the As014 had a launch speed (catapulted) of roughly 580kph that settled into a cruise speed of 640kph at it's typical altitude. Of course, air-launched speeds would be lower but it accelerated to it cruise speed within several minutes. Even the Fi103R (same As014 engine) had the same performances. It might be noted, that the V1 would achieve 800kph in it's dive. 

The JB-2, powered by the PJ31 engine slightly improved the cruise speed to 684kph. Then there was the JB-4, with the same PJ31 however, it's cruise speed was improved to 716kph. And post-war, the Junkers EF126, powered by the As044 managed to reach 780kph max.

Although a few Fi103Rs were found to have the As044 fitted, there is no record of a V1 being fitted with any so far as I have seen.


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## Koopernic (Apr 29, 2015)

Stona, Milosh, 

FuG 101a had the two ranges with the lower one very useful for blind landing, the FuG 101 had only the coarse one. 

The FuG 101 and its mechanical FM techniques was used as a basis of a proximity fuse for bombs called MARABU. The allies expected this and had developed techniques they thought would pre detonate it.

Basically a rapidly rotating motor was used to alter the frequency of a transmitter. By mixing the transmitted frequency (transmitted on say the left wing) with the received from a ground reflection (say on the right one) the phase difference indicated altitude.

I rather suspect MARABU would be a lot cheaper than FuG 101a and perhaps if only say +/-30m accuracy was required a cheaper device or a device working on different principles might do. German electronics engineers were very busy with anti jamming measures and developing a new generation of microwave radar at this time. 

The accuracy of Barometric instruments would I think be adequate to go down to 100ft. I believe altimeters work reasonably well to 20ft and might be relied upon so long as one had good topographic maps.


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## stona (Apr 29, 2015)

The motor speed was voltage sensitive and the PSUs were not consistent. The motor had to be calibrated to the PSU which was easy to do in a manned aircraft, trickier for a missile.

The separation of the transmitting and receiving antennae wouldn't be a problem. It had to be 1.4 -2.0 metres.







Cheers

Steve


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## Koopernic (Apr 29, 2015)

GrauGeist said:


> I keep seeing these figures and am wondering where they come from...



See post #53 in this thread. Speed improvements were achieved at development facilities around Jan/Feb 1945. Germany was soon split in two.

The long range Fi 103 "F-1" version which had less warhead, was lighter due to a wooden nose was also faster.


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## tyrodtom (Apr 29, 2015)

Barometric altimeters are set to the atmospheric pressure of where the aircraft takes off.

150 miles away it's usually going to be different. No problem for piloted aircraft because no pilot is going to expect 20 foot accuracy from a altimeter, or need it. He's got eyes.

Not so with a missile depending on a altimeter set to atmospheric pressure where the missile took off.


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## Shortround6 (Apr 29, 2015)

I think we are confusing radar altimeters with terrain following radar. Not at all the same thing. The first simply tells the pilot or auto pilot how high above the ground he/it is. The second measures the height of the ground in front of the aircraft and takes appropriate action to prevent contact from occuring. I would note that even anti-shipping missiles in the 60s could be adjusted for different sea states to prevent rogue waves from contacting missile. Rougher sea state called for higher altitude. 
Sorry but landing a plane at around 200 kph is a whole different thing than flying cross-country at 600kph at even 10 meters.


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## pbehn (Apr 29, 2015)

If it were possible to control the altitude to a low level why not a low powered prop driven version launched at night?


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## Shortround6 (Apr 29, 2015)

And since it would have much better range you could make it drop a bomb and return home for re-use. 

Wait a minute, that sounds like the Miles Hoop-la.


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## Koopernic (Apr 30, 2015)

Shortround6 said:


> And since it would have much better range you could make it drop a bomb and return home for re-use.
> 
> Wait a minute, that sounds like the Miles Hoop-la.



I believe the Fi 103 can trace its roots to a fly back piston powered aircraft, It was fairly small, more like a light aircraft. There are sketches of it about, I can't find any of it or the Hoop-la. It's obviously a far more complicated to return a vehicle then land it. Most early drones resorted to the idea of deploying a parachute than attempt fully automatic blind landing. Automatic blind landing had been achieved in Germany in 1940 but even then the pilot still had to cut the engines when the FuG101a told him he was a 2-3 meters of the ground and of course had set up the aircraft in the landing beam, set the autopilot to work of that beam and the right descent rate. It sounds attractive and it sounds possible with WW2 technology but there are so many little factors involved. 

If it was possible for the Oboe radar blind bombing system to send course corrections as audio signals to a pilots headphones its not much harder to convert those audio tones into suitable electrical signals that can trim in adjustments to an auto pilot. I think the problem is that one would need mechanisms for each phase of flight: take-off, cruise, bombing, return cruise, approach, landing plus something to stitch it together. Possible in 1940 but expensive and not reliable.




pbehn said:


> If it were possible to control the altitude to a low level why not a low powered prop driven version launched at night?



It might have done well, the pulse jet generated a huge flame that Mosquito pilots found easy to see from many miles away.




Shortround6 said:


> I think we are confusing radar altimeters with terrain following radar. Not at all the same thing. The first simply tells the pilot or auto pilot how high above the ground he/it is. The second measures the height of the ground in front of the aircraft and takes appropriate action to prevent contact from occuring. I would note that even anti-shipping missiles in the 60s could be adjusted for different sea states to prevent rogue waves from contacting missile. Rougher sea state called for higher altitude.
> Sorry but landing a plane at around 200 kph is a whole different thing than flying cross-country at 600kph at even 10 meters.



A radar altimeter does help to get down somewhat lower as one doesn't need to worry about navigating and consulting topographic maps simultaneously quite as much. Obviously one uses a different standard of 'low' for Essex versus say St Moritz.

I believe the terrain avoidance radar on the F-111 could conduct a 3G pull-up if it perceived terra firma ahead. This would pin the crew into their seats, essentially disabling them. It reacted not only off those funny little hills that jut out of the flat landscape in parts of Vietnam but sometimes a strong rain squall. Some kind of terrain avoidance radar was likely possible in WW2 but it certainly wouldn't have been priority.


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## nuuumannn (Apr 30, 2015)

I suspect some of you might be over thinking this.



> I would think one would have to just rely on launching many V1 from as many locations as rapidly as possible.



That was pretty much the gist of the V 1 campaign as it was. The Fi 103 was designed to be as simple as possible for rapid production in large numbers. The V 2 was more complex and far more devastating, although again, not precisely accurate to the degree that could be done with, say, dive bombing, but more so than the V 1 and far more difficult to counter once it had been launched.

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## kool kitty89 (May 1, 2015)

FLYBOYJ said:


> The man hour numbers are just that. You could factor that at a normal labor rate of consider the free "slave labor" that was available. You have to consider the cost of material, but regardless the sources at Wiki are showing that a complete V-1 airframe is nearly half the cost of a Jumo engine alone. Throw in the rudimentary guidance systems of the day and I see no way you could get "more bang for the buck" with what was available at the time. The V-1 was cost effective and IMO if introduced earlier in the war "would have" been more of a game changer than an earlier deployment of the Me 262.


I was suggesting possible compromises to get the best bag for the buck of a hypothetical throw-away turbojet design and the possibility of going slightly larger than the existing V1 to better justify the added engine assembly costs.

But then, the material costs might be more significant anyway (both in terms of using a smaller engine and a similarly sized V-1 airframe/payload). That and I was assuming larger engines of similarly simple design would be more cost effective (ie scaling down would be cheaper, but have diminishing returns in terms of cost to performance).

In any case, a slightly scaled down derivative of the HeS 3 of 1938/39 with similar cruise thrust (and higher static thrust) to the As 014 would have the advantages of being available sooner, avoiding development problems tied to vibration, and would consume less than half the fuel. (enough to make up for the heavier engine, if not more so)

Switching over to Pulse Jet power later on could certainly make sense if that proved more economical on the whole, but if a small, centrifugal compressor radial turbine jet engine could have been the earliest workable powerplant for a V1 style cruise missile, than that timing advantage alone may have made it worthwhile. (particularly if said jet technology was suitable for mass production only for very short-life engines)



The other question remains whether that would have been more cost effective than engineering similar engines into manned aircraft, and for that matter, raises the question of whether short-life turbojet designs would have been better suited to some of the attempted low-cost pulse jet powered fighters and attack aircraft. (given the valve life of the 014, a 'throw away' turbojet might have been attractive ... or a turbojet with a mostly throw-away hot section -or even just the turbine- intended to be totally replaced with frequent overhauls would have been fairly attractive, plus you'd save dramatically on fuel use)


There's a lot that could have been done with Ohain's early turbojets if you look beyond Heinkel's tunnel vision for fighter aircraft. (particularly ones intended to directly displace the Bf 109) Though ironically, Heinkel spread a bunch of resources between multiple follow-on designs from Ohain (derivatives of the HeS 8 ), Muller/Wagner's team, and several ducted fan designs based around Hirth's air cooled inline engines, yet the HeS 3 and 6 were abandoned.

For that matter, using Heinkel's jets as JATO boosters might have been useful as well. (and again, unlike the As 014, didn't have the serious vibration and noise issues -in fact, the LACK of vibration was Ohain's original inspiration for developing jet engines, intending to bring the elegance of glider-smooth flight to powered aircraft)


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## cherry blossom (May 1, 2015)

Not really on the thread topic except for where it diverged to take about altimeters etc but since many V1s were shot down by AA guns, it is not obvious that increasing the V1's speed will have a dramatic effect although it will obviously help. The success of British guns was probably considered very unlikely by the Luftwaffe as they did not know about the proximity fused shells. 

However, assuming that they realised what was happening, I have been considering what could they have done to reduce loses from AA. Would it have been possible for a V1 to fly a zigzag course by incorporating a timer and shifting the course from 30 degrees east of the true course to 30 degrees west of true every perhaps 20 seconds (ideally each bomb would have its own time set perhaps between 15 and 30 seconds)? Obviously that will cost some range. Naively reducing it only by a factor of 0.866 but actually much worse because speed will be lost during the turns. They could get some range back by adding a second timer to start the zigzag only as the V1 approached the British Coast. There will also be some loss of accuracy, which was bad enough when the bombs flew straight. Including the radio signalling system should reveal both the accuracy and, by comparison with bombs flying straight, whether zigzagging is worthwhile. It also seems that such V1s should be launch at night as the zigzag would allow British fighters to catch up if the pilots could judge what the V1 was doing.


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## tomo pauk (May 1, 2015)

The V1s were also engaged by 40mm cannons, even by 20mm Oerlikons Polstens? Add another 100 mph to the V1, as it was done in 1945 (yes, historically too late) and you have all but cancelled those light AA guns from the V1's threat list.


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## tyrodtom (May 1, 2015)

The V1 had only elevators and rudder for control surfaces, no ailerons. Only slow, gradual, course corrections were possible.
That's why tipping the V1 brought them down. You only had to tilt the aircraft beyond the ability of the 2 axis control to recover, and it went out of control.

Zig-zaging , unless very gentile , would be beyond what a 2 axis could do.


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## Koopernic (May 1, 2015)

According to Wikipedia by *March 1944* Fi 103 V1s were produced in *350 hours (including 120 for the autopilot*).

Figures from Anthony Kay's "German Gas Turbine and jet engine development 1933-1945" *for the BMW 109-003A-2 taking 600 man-hours out of a planned 500.* These are actual German figures and conform with the production engineers Dr Fattners estimates of 500 man-hours per engine. 

The Porche 109-005 of course had to produce about 50% less thrust and was required to have a total life of only 2 hours as opposed to a MTBO of 25 hours for the 003A2 (probably refurbished 4 times if no combat damage)

It's therefore not conceivable that the Porche 109-005 or simply 005 could be 50% x 50% less cost ie 25% as much (say 150 man hours) than the man rated BMW 003A2.

Noteworthy is that this doesn't include the cost of raw materials it such as sheet stock. Material is not expensive if steel but can be used but unless it includes nickel and chromium due to the high cost of mining and refining it. If the turbine inlet temperatures are kept below 650C the turbine can be made a 2 hours throwaway item of pure steal, this is what was planed for some of the German jet engines. Your turbojet is inefficient and big but its still better than a pulse jet.

If we assume the V1 cost 230 hours (excluding autopilot) and that 25% of this cost was the pulse jet (57.5 hours) then substituting the turbojet only adds 90 hours cost.

Out V1 now costs not 350 hours but 440 hours total and has both more accuracy and range. If we assume the electronics for guidance system (Ewald 2 also known as Ewald-Sauerkirsche added the same as the autopilot again (120 hours) we end up with a long range turbojet powered guided V1 for *560 hours* compared to 350 hours for the short range unguided versions. 

Some things are known of the 109-005. *It used a geared compressor to optimise both *the compressor and gas turbine. Though this sounds fancy (geared compressors are absolute state of the art Pratt and Whitney tech) this is a small gearbox that could be cast and machined in one piece. It would considerably reduce project risk as matching the compressor to the turbine is simplified by adjusting the gear ratio. It was also intended to shed ice.

The BMW disposable turbojet was of a conventional design.

So yes a guided turbojet powered V1 was probably only 50% more expensive as a shorter ranged unguided one and even if it were twice the price it would be 'affordable'. If you say its twice as expensive I say its still cost effective.

Interestingly the Germans experimented with the idea of semi disposable aircraft that were pulse jet powered. The deposable 109-005 gave these projects, such as the Me 328 a new life.

The Ewald 2 guidance system worked by receiving a single pulse from the V1 missile whose differences in arrival times in 3 fixed ground stations allowed a position to be calculated. Now consider that Three carrier aircraft launch a missile each. At a certain point one of the missiles emits its location pulse which are received by all three aircraft and then instantly relayed to three ground stations. There is now enough information from the differences in arrival time to locate not only the position of each of three aircraft but the missile.

Hence air launched turbojet powered guided V1 allow for considerable potential in long range and reasonably accurate guidance.

The reason I know it works is because the US built the Loon and that means an independent set of highly competent military officers and engineers analysed it.



Figures from Anthony Kay's "German Gas Turbine and jet engine development 1933-1945" for the BMW 109-003A-2 taking 600 man-hours out of a planned 500.
German Production Costs

This is much less than a piston engine. 

Breakdown is: 

Machining 220 
Sheet Metal Work 160 
Starter Governor 60 
Miscellaneous 100 
Assembly 60 

There are further breakdowns with the 66 turbine rotor blades requiring *only 10 hours*. 

Of course this doesn't cover the cost of refining and transporting metals and raw materials. 

The time taken for the Jumo 004 was 700 manhours. (But remember cost drop as production is refined.

In both engines there was very little nickel, chromium or manganese. At most 6kg of each with nickel virtually eliminated to 200 grams in some versions. Nickel was in very short supply.

The website Vorwort lists the manhours required for a BMW 801 as 

"Durch eine Optimierung der Fertigung wurden die Preise für die Motoren immer weiter gesenkt. Der Preis einer BMW 801 Motoranlage lag 1940 bei 80700 RM und Ende 1942 nur noch bei 45000 RM. Davon entfielen 35600 RM auf den Motor und der Rest auf das Kommandogerät (3000 RM) und die Verkleidung des Motors (6400 RM). Die Anzahl der Fertigungsstunden betrug Ende 1942 etwa 16000 Stunden pro Motor." 

Or in English 

"The prices for the engines were continuously lowered by an optimization of manufacturing. The price of a BMW 801 engine was in 1940 80,700 RM and at the end of of 1942 only 45,000 RM. Of this 35,600 RM were allotted to the engine and the remainder to the control unit (3,000 RM) and the lining of the engine (6,400 RM). The number of manufacturing hours amounted to at the end of 1942 about 16,000 hours per engine." 

I would assume that a V12 engine like the DB603 would be about the same.


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## stona (May 1, 2015)

Adding more sophisticated control surfaces, just like adding more sophisticated flight instruments like radar altimeters, is a waste of time, money and resources. If the Germans had wanted to create a more sophisticated weapon system they would have needed a different platform for it and most obviously a better guidance system. The only thing the V-1 had going for it was it's cheapness, take that away and there's not much left.
Cheers
Steve


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## Koopernic (May 1, 2015)

stona said:


> Adding more sophisticated control surfaces, just like adding more sophisticated flight instruments like radar altimeters, is a waste of time, money and resources. If the Germans had wanted to create a more sophisticated weapon system they would have needed a different platform for it and most obviously a better guidance system. The only thing the V-1 had going for it was it's cheapness, take that away and there's not much left.
> Cheers
> Steve



_That would be partially true but adding a bit of electronics and a substituting a turbojet *doesn't* increase the cost very much._

Adding turbojets and even optionally adding electronic guidance combined probably only adds 50% at most 90% to the cost of the V1, so its not going to take away its cheapness.

It will *double* the range and increase accuracy by about a *factor of 8*. The expectation of accuracy for Ewald Sauerkirsch guidance was around 2km, depending on where the mid course update was done it could be much better.

Vacuum tubes are only little pieces of glass and steel. The electrodes that penetrate the glass are made of copper clad iron filaments which have the same thermal coefficient of expansion of glass and platinum. The Germans started making the heating filaments out of titanium (a material they had) as tungsten became scarce but I suppose they could have used even carbon filament's to heat the cathodes.

The alternative is to just throw more V1's into the air and accept that only 20% are going to hit built up areas. The problem with this is that even if you have man hours to throw at a problem its no good if you don't have steal, there being only so much wood that could be used.

The "over the radar horizon" guidance system I postulated based on the Ewald system requires no new electronics on the missile, the computation is done in the ground stations and they relay aircraft equipment is also simple and not thrown away.

The radar horizon of a V1 at 1000m is about 140km so if this is the chosen cruising altitude that is where the midcourse update would be. Of course the V1 could fly higher, the ground stations could be atop 100m towers (which adds quite a bit) or the ground stations might even be relay aircraft. There are no fancy Adcock direction finding antenna, just timing signals.

One would think that unguided V1's would I expect be used as seductive decoys to hide the guided ones which would be targeted towards high value areas.


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## FLYBOYJ (May 1, 2015)

kool kitty89 said:


> I was suggesting possible compromises to get the best bag for the buck of a hypothetical throw-away turbojet design and the possibility of going slightly larger than the existing V1 to better justify the added engine assembly costs.
> 
> But then, the material costs might be more significant anyway (both in terms of using a smaller engine and a similarly sized V-1 airframe/payload). That and I was assuming larger engines of similarly simple design would be more cost effective (ie scaling down would be cheaper, but have diminishing returns in terms of cost to performance).


 Full size turbine engines of the day barely worked, you think a 'scaled down version' was worth it?


kool kitty89 said:


> In any case, a slightly scaled down derivative of the HeS 3 of 1938/39 with similar cruise thrust (and higher static thrust) to the As 014 would have the advantages of being available sooner, avoiding development problems tied to vibration, and would consume less than half the fuel. (enough to make up for the heavier engine, if not more so)


 Wishful thinking, again full size engies were barely functional.


kool kitty89 said:


> Switching over to Pulse Jet power later on could certainly make sense if that proved more economical on the whole, but if a small, centrifugal compressor radial turbine jet engine could have been the earliest workable powerplant for a V1 style cruise missile, than that timing advantage alone may have made it worthwhile. (particularly if said jet technology was suitable for mass production only for very short-life engines)


Again you're assuming that a small, RELIABLE and cost effective turbine engine could be produced to make the increase in performance and cost worth wild, I just don't see it based on the technology and resources available at the time. The Pulse Jet was the perfect engineering solution.



kool kitty89 said:


> The other question remains whether that would have been more cost effective than engineering similar engines into manned aircraft, and for that matter, raises the question of whether short-life turbojet designs would have been better suited to some of the attempted low-cost pulse jet powered fighters and attack aircraft. (given the valve life of the 014, a 'throw away' turbojet might have been attractive ... or a turbojet with a mostly throw-away hot section -or even just the turbine- intended to be totally replaced with frequent overhauls would have been fairly attractive, plus you'd save dramatically on fuel use)


How much thrust you think a smaller engine would have produced? In reality the first jet fighters were underpowered when you consider their weight.

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## GrauGeist (May 1, 2015)

Koopernic said:


> *See post #53 in this thread.* Speed improvements were achieved at development facilities around Jan/Feb 1945. Germany was soon split in two.
> 
> The long range Fi 103 "F-1" version which had less warhead, was lighter due to a wooden nose was also faster.


I had assumed we were discussing units actually used in combat, not prototypes and test specimens.

Otherwise, we can stray into all sorts of 1946 projects that included As014 and As044 engines...


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## FLYBOYJ (May 1, 2015)

GrauGeist said:


> I had assumed we were discussing units actually used in combat, not prototypes and test specimens.
> 
> Otherwise, we can stray into all sorts of 1946 projects that included As014 and As044 engines...

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## pbehn (May 1, 2015)

surely a turbo jet that only has to run at one setting for an hour is cheaper than those fitted to a 262?


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## Koopernic (May 1, 2015)

cherry blossom said:


> However, assuming that they realised what was happening, I have been considering what could they have done to reduce loses from AA. Would it have been possible for a V1 to fly a zigzag course by incorporating a timer and shifting the course from 30 degrees east of the true course to 30 degrees west of true every perhaps 20 seconds (.



Obviously the AAA was very effective. I'm of the mind that the AAA expended cost about the same as the V1.

I would imagine a small clockwork driven camshaft could be unlatched when the V1 was approaching the coast, they could mechanically alter the course of the V1 over say 7km. It would of course slow the V1 down giving the guns more time to engage and this would need to be considered.

Coming in ultra low might be a possibility, down to say 100m to minimise warning time.

There were two seekers developed at this time in Germany: MAX-A which was a simple active homing warhead using continuous wave Doppler intended mainly for surface to air missiles. I assume the A stood for Aktiv. A cut down variant of it was called MAX-P, presumably P for Passiv. It was designed to home onto H2S and H2X and the radars of Allied night fighters. Obviously it might be placed in the V1 and be directed straight at the SCR-584. If several missiles are launched including a few decoys one will eventually get through. 

There was a glide bomb called the BV-246 that seemed to have a glide ratio of about 25:1 do released at 10,000m might have a range of 250km. It was tested with a radar homing warhead called Radischien and got to within 5m of target. Radischien wasn't a microwave seeker but it was flight tested. MAX-A/Max-P was tested but only seeking targets in the laboratory or field.

There is nothing unbelievable about a pulse jet flying at 515mph at sea level. Its the speed Me 262 and P80A were doing. The Fi 103"F1" was faster than the standard Fi 103.


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## GrauGeist (May 1, 2015)

FLYBOYJ said:


>







pbehn said:


> surely a turbo jet that only has to run at one setting for an hour is cheaper than those fitted to a 262?


But think about the economic difference between a turbojet (even a small one) versus a pulsejet both in material and time


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## Koopernic (May 1, 2015)

GrauGeist said:


> But think about the economic difference between a turbojet (even a small one) versus a pulsejet both in material and time



Figures from Anthony Kay's "German Gas Turbine and jet engine development 1933-1945" for the BMW 109-003A-2 taking 600 man-hours out of a planned 500.

Breakdown is: 
Machining 220 
Sheet Metal Work 160 
Starter Governor 60 
Miscellaneous 100 
Assembly 60 

There are further breakdowns with the 66 turbine rotor blades requiring only 10 hours. 

Let's cut into that:

1 We don't need a starter motor, blow in some compressed air
2 being a bit smaller means you are simply machining and cutting less.
3 smaller parts mean less parts as two items can often be fabricated as one.
4 we now have a rotating shaft to add an alternator and a supply of 3 bar compressed bleed air that might run the autopilot and get rid of the compressed air bottle. Not saying you'd do that but it might be an latter option and it would allow more fuel.
5 less vibration equals lighter mountings. 
6 single use spark plugs, external electrical ignition source, or some other mechanism.
7 no throttle, control by an external Allen key that sequences start up.
8 no fuel delivery pump, blow in air from compressor or compressed air bottle. There are pressure doubling devices since fuel pressure probably needs to be greater than compressor pressure.
9 cheaper alloys.
11 less conservative engineering


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## stona (May 1, 2015)

I'm not sure any of the above would realistically reduce the cost to the sort of levels that would make a turbojet competitive with a pulse jet. Some of the points seem to be wishful thinking.

Cheers

Steve

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## GrauGeist (May 1, 2015)

Compare that to the build time of an Argus (014 or 044) AND factor in the amount of materials used to build it.

Another consideration: the materials used to make "mini" turbojets would be diverting much needed labor and materials away from the jet aircraft, which were sorely needed.


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## stona (May 1, 2015)

GrauGeist said:


> Another consideration: the materials used to make "mini" turbojets would be diverting much needed labor and materials away from the jet aircraft, which were sorely needed.



A valid point. The Germans were short of Nickel, Cobalt and Chromium which led to the use of 'mild' steels where other alloys would have been better suited in the Jumo engines of the Me 262. Diverting limited resources to yet another turbo jet project could only have exacerbated an already difficult situation.

Not for the first time in a thread which seems to be utilising hindsight to a great extent will I type, resources, resources, resources.

Cheers

Steve

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## pbehn (May 1, 2015)

stona said:


> I'm not sure any of the above would realistically reduce the cost to the sort of levels that would make a turbojet competitive with a pulse jet. Some of the points seem to be wishful thinking.
> 
> Cheers
> 
> Steve



As a teenager a friend of mine made a wooden piston for his moped, it ran very badly for five minutes but it ran, i would say if a turbine only has to run for maybe 30 to 60 minutes very simple alloys with larger tolerances could be used.


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## Shortround6 (May 1, 2015)

Or not so large tolerances. 

Westinghouse J32 - Wikipedia, the free encyclopedia

9.5 in diameter, 260lbs thrust, 34,000 rpm. 

The bigger J-30 ran at 18,000rpm. 

At the RPM the jet engines turned large tolerances could spell disaster in _very_ short order. Quite literally as the turbine disk and/or compressor disk/s stored an immense amount of energy and a failed disk could be like a bomb going off. 

The GE J-85 was originally designed to be a short life engine (for target drones)as were the Armstrong Siddley Adder and Viper and others. While they used short life materials and simplified oil systems I doubt that sloppy tolerances would have allowed them to run for even a few minutes.


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## kool kitty89 (May 2, 2015)

Koopernic said:


> Noteworthy is that this doesn't include the cost of raw materials it such as sheet stock. Material is not expensive if steel but can be used but unless it includes nickel and chromium due to the high cost of mining and refining it. If the turbine inlet temperatures are kept below 650C the turbine can be made a 2 hours throwaway item of pure steal, this is what was planed for some of the German jet engines. Your turbojet is inefficient and big but its still better than a pulse jet.


Not to mention the configuration Ohain used with centrifugal compressor and (especially) radial turbine was good for a number of reasons that also made it less practical to scale up. The radial turbine was large and heavy and used a lot of material, but also coped with mechanical and thermal stressed far better than an axial turbine and was somewhat easier to match with a compressor (in terms of power and flow rate). Of any turbine design, including hollow blades, that early one that worked so well as a short-term proof of concept would have been the one best suited to using mild steel.

In fact, I suspect Ohain may have been able to get his original 'garage' engine working if he'd started smaller, something small enough to easily get up to full RPM on compressed air (rather than an electric motor) and given more chance to work on the combustion issues. (using compressed hydrogen on a small model -even one using common mild sheet steel like the garage engine, shouldn't have been that hard to get working between Ohain's engineering abilities and Otto Han's sheet metal, machining, and mechanic/technician experience -more so if you assume a good deal of the components were cannibalized from existing automotive or aircraft parts/scrap -particularly the bearings)

One of the bigger breakthroughts in Ohain's jet design was finally getting liquid fuel combustion working after adapting the vaporizer arrangement used in a soldering torch (blow lamp). Stable combustion was one of the most consistent problems on nearly all early turbojet designs, Jumo got a bit lucky with a fairly good flame tube design developed early on while Ohain got away with the vaporizing annular combustion arrangement OK on the HeS 3 and 6, it proved no end of trouble in the later HeS 8 with combustion stability and turbine overheating issues significantly worse than expected from experiences with the preceding engines. (I'm not sure on the specifics, but given the actual design of the engines, the airflow routing of the HeS 8 is much more convoluted and cramped than the HeS 3 and 6, with much smoother flow for those earlier designs -the diffusor chamber lies in front of the compressor curving rearward to the flame holders in a ring of combustion jets in square outlets flowing straight back, parallel to the rotor shaft and then smoothly curving around the end of the combustion chamber into the radial inflow guide vanes for the turbine)


It wasn't until watching this video that I finally got a good idea of how it worked. 
_View: https://www.youtube.com/watch?v=z_RSHrGKyDg_


Ohain's design also emphasized the use of sheet metal and minimized machined parts, reducing cost and skilled labor requirements on top of precious high speed cutting steel. (a very serious concern for machined aluminum compressor rotors and also one of the concerns over the machined reaction compressor blading of the HeS 30)

That was in fact one of the areas that intrigued Milch initially: the ability to build engines using materials and labor far less that that of the existing piston engines. (though you'd obviously still need some level of precision balancing and fairly tight tolerances in general -everything that applied to the 004B and 003 in production later on) The flexibility of fuels used (at least once the combustion problems were solved) were the other big deal. (the vaporizing burner arrangement was workable, but did complicate the start-up sequence or require easily vaporized fuels and would make re-starting in-flight difficult, but that was a problem for the 004B as well)


A ton of the early problems were tied to reliability issues specific to ability to use in conventional manned aircraft. Compromises made for a short-life engine could have side-stepped many of those issues and allowed a production ready design much sooner.

Ohain's designs also had better thrust to weight ratios than the 004 and to lesser extent 003, and that's as-is in 1939. (compared to production ready 003A and 004B -let alone the poorer thrust to wright of the heavy 004A) They actually fared better than Whittle's designs prior to the W.2. (Welland)

For that matter, Whittle's prototypes likely would have been functioning on the test bench much sooner if he'd started off with scale models using hydrogen fuel, or perhaps propane, ether, or methanol. (gasoline and kerosene offer a good deal more headaches for stable combustion, clogging from soot on start-up, etc)

Ohain and Heinkel's engineers made a great deal of compromises and short-cuts to get a working engine in the minimum time possible, things that undoubtedly were unattractive for the long-term but not out of the question for extending to mass production. (unlike say the compromises in Jumo's 004A using substantial amounts of refractory alloys, or Whittle's prototypes -AND production engines- using massive, expensive single-piece machined aluminum impellers)




> So yes a guided turbojet powered V1 was probably only 50% more expensive as a shorter ranged unguided one and even if it were twice the price it would be 'affordable'. If you say its twice as expensive I say its still cost effective.


unless the fuel savings made up for the cost (or overall logistical cost -not just monetary) there's still major advantages for the pulse jet. However if a disposable turbojet would have allowed /earlier/ introduction of such a missile AND made it more reliable and easier to develop further (particularly anything associated with vibration), there would be those advantages as well. (even for the same size missile and same payload, if accuracy was improved thanks to a combination of factors hinging on use of a turbojet, it might totally displace advantages of the pulse jet, or merit producing both side by side and varying production volumes depending on available resources -different resource bottlenecks could favor one as being less costly than the other, including the turbojet using less than half the fuel to get to the same target)




> Interestingly the Germans experimented with the idea of semi disposable aircraft that were pulse jet powered. The deposable 109-005 gave these projects, such as the Me 328 a new life.


Mode of failure on short-life engines becomes more significant for manned aircraft, something that severely impacted the XP-80A testing though not so much with other early tests. (The P-80 is the only one of the early jets I'm aware of having the engine actually explode -impeller and/or turbine shattering and shearing off the rear fuselage) 

It's worth noting that Heinkel's early engines were tested to the point of turbine burnout several times, but none catastrophic to the aircraft they were tested on. Turbine burnout on the 004B didn't tend to be catastrophic either from what I understand. (though ruptured combustion chambers and engine fires would be more serious)

In any case, engineering for controlled failure would be important for anything manned.



Additionally, short life engines could omit the starter entirely, relying on an external power source for start-up. (reducing weight, cost, and complexity)



> In both engines there was very little nickel, chromium or manganese. At most 6kg of each with nickel virtually eliminated to 200 grams in some versions. Nickel was in very short supply.


This was true late-war but not nearly as much early on. Initially, chromium was more the bottleneck for stainless steel alloys (used in all sorts of applications -including piston engines) but losing access to Finnish Nickel late-war was a major blow to that.

They also hadn't stockpiled strategic materials, so late war shortages would NOT have been exacerbated by heavier use or diversion earlier on. (of course, overall logistical resource management at ANY point in the war was significant, but the point that jet engines could be engineered to use significantly LESS nickle and chromium than front line piston engines being built in 1939 is something often overlooked)
Honestly, with the high wear rate, I'd be more concerned with the potential of scavenging and recycling burned out turbines and such for strategic materials. (granted, a non-issue for disposable engines that do away with stainless steel entirely -the cold section would be more valuable there, especially for possible rotation through overhaul and re-use as on the 004B)


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## GrauGeist (May 2, 2015)

kool kitty89 said:


> *Ohain's designs also had better thrust to weight ratios* than the 004 and to lesser extent 003, and that's as-is in 1939. (compared to production ready 003A and 004B -let alone the poorer thrust to wright of the heavy 004A) They actually fared better than Whittle's designs prior to the W.2. (Welland)


That's why the He280 was smaller and more nimble than the Me262...as well as not being able to accept the 003 or 004 as a substitute.

Anyway, compare the amount of time and materials to construct a turbojet versus the amount of time and materials needed to construct a pulsejet.

In the situation that Germany was in at the time, it made sense to focus on the Argus as a means of propulsion for the V1. The As044 was a better engine, but it was slow to come to production (being developed late war) and too late in the war to be of any good.

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## kool kitty89 (May 2, 2015)

GrauGeist said:


> Compare that to the build time of an Argus (014 or 044) AND factor in the amount of materials used to build it.
> 
> Another consideration: the materials used to make "mini" turbojets would be diverting much needed labor and materials away from the jet aircraft, which were sorely needed.


Labor and resources needed for turbojet manufacture was simpler and less demanding than a good deal of other industries, including piston engine production and, beyond that I'm mainly postulating turbojets in use BEFORE they're ready to be used for anything else. (though said throw-away jets might find their way into specialized manned aircraft as well)

The cheapness of pulsejets still is its own advantage, but the trade-offs of the pulse jets design and the relatively primitive implimentation of the As 014 itself leaves many other drawbacks that potentially increase total aircraft/missile cost, slow development/deployment, or hinder operational effectiveness. (had there been more effort in investigating pulse jets pre-war, there's probably a lot more use they could have gotten out of them and a much wider range of sizes and thrust levels among other things -having ONLY the As 014 was pretty limiting, including the fact that a larger number of SMALLER pulsejets may have been much easier to adapt due to the higher frequency pulsing and lower noise levels -especially when combined with additional external cowling/ducting) 

The first functional pulse jets were being explored in Russia prior to WWI, but development seemed to languish and dead end during/after the war, particularly after the Soviet takeover. (or perhaps due to the similar lack of interest in such propulsion means explored elsewhere) A french patent for a valveless pulsejet had also been made prior to WWI and valveless designs have even more potential, particularly for longer life engines without sudden/sporadic failure due to valve wear. Given the amount of research that went into ram jets, putting more effort into pulse jet designs (especially sooner) would have had many, many more practical applications from military to hobby/entertainment/novelty use. (really, little pulse jet, free-flying model airplanes would have made great novelties in the early 20th century)

Again, there's a great deal of fascinating information here:
Valveless Pulsejets 1.5 By Bruno Ogorelec

In fact, if the valveless designs got good enough, it could be worth investing in stainless steel construction to further prolong lifespan. (especially in the case of re-usable JATO booster systems, either fixed or droppable -though using cheap, expendable mild steel jets might make more sense there and avoid the parachute system used for some liquid fuel RATO units)




pbehn said:


> As a teenager a friend of mine made a wooden piston for his moped, it ran very badly for five minutes but it ran, i would say if a turbine only has to run for maybe 30 to 60 minutes very simple alloys with larger tolerances could be used.


There's actually a video of a really neat mostly plywood home-made turbojet engine on youtube, but I can't seem to find it right now. I think it was just the compressor and diffuser that were wood, but I forget the details. (it was self sustaining and ran on propane)

Edit, found it:
youtube.com/watch?v=L3hZPQT1Nuw





Koopernic said:


> 1 We don't need a starter motor, blow in some compressed air
> 2 being a bit smaller means you are simply machining and cutting less.
> 3 smaller parts mean less parts as two items can often be fabricated as one.
> 4 we now have a rotating shaft to add an alternator and a supply of 3 bar compressed bleed air that might run the autopilot and get rid of the compressed air bottle. Not saying you'd do that but it might be an latter option and it would allow more fuel.
> ...


I think all those points are valid, though scaling up/down when dealing with aerodynamics and mechanical engineering is far from linear, and the bigger change in scale the greater potential variables to address. But at least in the case of Ohain's designs, the compressor and turbine arrangement should have been very close to ideal for scaling down. (and that is if the existing HeS 3 wasn't directly adapted as-is -it's weight and thrust are such that they'd fit reasonable well on a missile with the payload and range of the V1, at about half the weight and 50-60% the thrust)

I'm not sure the less conservative engineering would necessarily apply either. Some tolerances might be wider, but a good deal of precision and quality control would still be necessary.






GrauGeist said:


> That's why the He280 was smaller and more nimble than the Me262...as well as not being able to accept the 003 or 004 as a substitute.


The 003 might have been reasonably suited, but was too delayed to be useful for testing. Pulse jets were never successfully tested but at least considered. (thrust to weight was right, and fuel consumption and short valve life might have been OK as a point interceptor, but I doubt the vibration issues and radiant heat would mesh well with airframe longevity)

I should also clarify that the thrust to weight wasn't THAT much better, but it was still notably better, especially with the versions of the HeS 8 just prior to cancellation, but the sheer low weight was also important more than thrust to weight ratio. The poorer performing early HeS 8 models were barely better than the Jumo or BMW engines (well ... once the Jumo was running at full sped at least, not the initial <1000 lbf runs, or 1,300 lbf RLM minimum thrus requirement runs) and slightly worse than the previous HeS 3 and HeS 6 (overall performance of the initial HeS 8 runs were very similar to the HeS 3, except they had even more reliability problems). The HeS 8's bigger claim to fame was managing a small frontal area while using a centrifugal impeller. (thrust to frontal area was far better than any centrifugal engines until well after the war, but the methods used for achieving that are also likely the main reasons it was so troublesome to develop -the ideas might have been more useful in a larger class II follow-on design, and certainly should have gone more smoothly and practically than the arrangement in the HeS 011 while being much lighter than that engine and only slightly wider for similar thrust, but it really seems like abandoning the more workable HeS 3 and 6 in 1939 was unfortunate -it'd be a bit like Whittle totally abandoning work on the W.1 before progressing to the W.2 and starting a much more radical new design ... say the Nene or Derwent V or maybe J33 -more radical than the Derwent I for sure ... and certainly not like Halford's Goblin -a design that specifically went for simpler, more conservative design features at the expense of weight, compression ratio, and diameter in favor ease of development -the Goblin is the sort of Centrifugal design Germany should have been developing ... it's the centrifugal counterpart to Jumo's conservative 004 design philosophy)

It was the HeS 30 that had the really outstanding thrust to weight figures



> Anyway, compare the amount of time and materials to construct a turbojet versus the amount of time and materials needed to construct a pulsejet.
> 
> In the situation that Germany was in at the time, it made sense to focus on the Argus as a means of propulsion for the V1. The As044 was a better engine, but it was slow to come to production (being developed late war) and too late in the war to be of any good.


I agree for the most part, and I think I explained the more intricate exceptions behind my own supposition above. (in as far as potential early-war turbojet use -and even then, it might have been a waste to use short life turbojets on missiles rather than point interceptors or maybe even recon aircraft ... maybe short range attack or glide bombers? -like the Hs 132 concept but say 3 years sooner)

That said, while not understanding the changes in the As 044's overall design itself, it seems like basic improvements could/should have been made to the 014's design that shouldn't have been hard to implement in production. (cowling and thrust augmentor designs would have been most significant ... and if nothing else the simplest arrangement to at least attempt would be a single peice cylindrical metal shroud running the entire length of the exhaust pipe just rear of the intake/resonant combustion chamber bulb, covering the hottest parts of the engine and acting as a primitive ram-cowling of sorts -more aerodynamically efficient configurations should have been possible, but that's the simplest/easiest to implement, a thrust augmentor as typically used by hobbiests with pulse jets currently would have been simpler and lighter but perhaps less obvious to attempt, and maybe not as effctive given the sheer amount of heat the tailpipe produces)

youtube.com/watch?v=j4hBwCDRwK0 gives a nice showing of just how hot the thing gets


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## davparlr (May 6, 2015)

I have not read all the post in detail so some of this is probably already said.

1. V-1 bombing (and to a larger extent, V-2 bombing) was not nor would ever be an effective interdiction weapon. Accuracy was never available in WW2 to provide a reasonable one bomb one hit performance. Probably, this would not become available until GPS entered the scene. Without this, the Germans were throwing pin pricks at the Brits (unless it was you who was at ground zero). 

2.	Improving speed, range, and survivability would not have much of an impact on British logistics. Even if all the 9000+ V-1 launched hit London, it would have had little impact on the war. In just one 24 hour period, Bomber Command dropped 10,000 tons of bombs on the Germans, and they still fought on effectively. How many tons of bombs were being dropped on Germany on a daily bases?  I suspect a lot more than 9000 tons, the total amount of all the V-1s.

3.	As pointed out to me on a previous thread, the big impact of the V-1 was the diversion of forces to counteract the V-1. I think that probably the greatest impact to that would have been more launches not longer ranges, faster flying, or more accurate (still poor) weapon delivery.

4.	I’m sure that simply reducing the size of the jet engine does not make the development or manufacture any easier, it would reduce materials, and I certainly don’t believe it is nearly as cheap as a stove pipe with flapper valves and stove burners (I’m being facetious, I really mean blow torch) to build. And I suspect it would require more skilled labor.

5.	I think the V-1 was ideal for the job. Cheap and simple and easy to build thousands and saturate enemy defenses. If they had those during the Blitz it would have cause all kinds of problems for the Brits.

6.	So, don’t waste money and resources and engineering development on a better weapon, it would be counterproductive like building the V-2.

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## kool kitty89 (May 7, 2015)

davparlr said:


> 3.	As pointed out to me on a previous thread, the big impact of the V-1 was the diversion of forces to counteract the V-1. I think that probably the greatest impact to that would have been more launches not longer ranges, faster flying, or more accurate (still poor) weapon delivery.
> 
> 5.	I think the V-1 was ideal for the job. Cheap and simple and easy to build thousands and saturate enemy defenses. If they had those during the Blitz it would have cause all kinds of problems for the Brits.


Hmm, regardless of engine used, the system might have been effective as a decoy (with bomb delivery as a secondary goal) in drawing out British forces and exacerbating their already strained conditions early-war, particularly while the LW was concentrating on Fighter Command and Chain Home. They had engines (of some sort -not the production As 014) flying in 1938 and the principal is simple enough (more so if you compromise on easier to vaporize/burn fuel used -possibly cheaper fuel too). Possibly even larger missile bodies/wings with speed less critical and mimicking manned aircraft somewhat more useful. (plus more compromises in design to address vibration issues without as tight a need for weight or drag reduction, or being able to reach london -the coastal RAF targets, or the surrounding area would be the goal)

Might it even be possible to get them flying stable enough with even simpler autopilots able to be introduced sooner? (air launching might ease this, but that adds to operational cost ... still might have been a cost effective way to spread our and wear down british resources without risking/losing nearly as many German manned aircraft)





> 4.	I’m sure that simply reducing the size of the jet engine does not make the development or manufacture any easier, it would reduce materials, and I certainly don’t believe it is nearly as cheap as a stove pipe with flapper valves and stove burners (I’m being facetious, I really mean blow torch) to build. And I suspect it would require more skilled labor.


In the case of the 004: compromising with a smaller turbine, fewer compressor stages, lower compression, lower turbine temperature, short operation life, among other things could have simplified mass production as well as production using non-strategic materials.

That said, my main focus was on the much earlier Heinkel engines running in 1938/39 and their potential. 

And on combustion: from what I've seen the injectors on the 014 are actually more like a stove than blow torch ... even the HeS 3 was more of a compromise between a stove and torch burner lacking a flame tube and using a grille/grid along with part of the diffuser as the flame holder in the jets. They were very primitive, simple combustion arrangements indeed, and relied on vaporized (or gaseous) fuel to work properly. Jumo's flame tube design may have been the first developed to be really practical (the flame cans with combustion tubes, swirl inlets, and fuel atomizers were functional well ahead of other British or German designs and likely would have been a boon to both BMW and Heinkel's developments -though Wagner/Muller's team seemed to adopt a similar arrangement on the HeS 30).

It's actually a bit baffling though, given the similarities between Jumo's combustors and a common blow lamp, with a few modifications. The flame holders and combustion jets used in many other designs seemed to totally miss this idea.


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## Koopernic (May 8, 2015)

davparlr said:


> 1.	V-1 bombing (and to a larger extent, V-2 bombing) was not nor would ever be an effective interdiction weapon. Accuracy was never available in WW2 to provide a reasonable one bomb one hit performance. Probably, this would not become available until GPS entered the scene. Without this, the Germans were throwing pin pricks at the Brits (unless it was you who was at ground zero). .




Both the V1 and V2 were always meant to have precise electronic guidance systems. It was decided to employ them with crude guidance primarily because they could be gotten into service quicker. Guidance systems did however continue to be developed: for instance about 25% of V2 launched used an electronic beam.

The V1 ‘worked’ as a weapon, despite its inaccuracy, because it was cheap. It could perform the equivalent of area bombardment. Of the 9000 launched some 2000 are credited with getting through which is credited with damaging 110,000 houses. I assume, following the 80:20 rule, that perhaps only 22,000 of those houses were thoroughly destroyed. The first V1 to reach London in fact destroyed a railway bridge not a house. The V1 would be destroying factories, shops, warehouses, bridges, offices in proportion to their area.

Assuming the system had an accuracy of 8km, how much would it be worth to double this accuracy to 4km or 2km or 1km or even 100m? That latter kind of accuracy *was* available in WW2 from systems such as *Oboe* or its German equivalent *EGON II.* In Oboe simple morse code signals gave simple commands to the pilots and observer, in EGON II with Nachtfee a dial pointed to the commands, about 20. What’s to stop the commands being used to trim a modified heading into the autopilot? The smarts, the expensive precision was in the ground station.

Because the V1 was a cheap weapon doesn’t mean It couldn’t be upgraded to an more expensive but much more accurate guided version and that this would mean the weapon was no longer worthwhile.

More range and accuracy widens the range of targets outside of the Greater London area and makes it possible to target large factories.



davparlr said:


> 2.	Improving speed, range, and survivability would not have much of an impact on British logistics. Even if all the 9000+ V-1 launched hit London, it would have had little impact on the war. In just one 24 hour period, Bomber Command dropped 10,000 tons of bombs on the Germans, and they still fought on effectively. How many tons of bombs were being dropped on Germany on a daily bases? I suspect a lot more than 9000 tons, the total amount of all the V-1s. .



The Arado works in Late 1943 employed 16,000 people in production of the Heinkel He 177 while a large number were likely at Heinkels own facility. If 16000 people worked a 48 hour week they produced 768,000 hours. This could produce in 1 week:
1 2,194 V1’s at 350 hours each. (I fact about a production rate of 10,000 month is what seems to have been available)
2 192 V2 missiles at 4000 hours each (the figure for the 10,000th produced)
3 38.4 He 177 at 20,000 hours each. In fact the 20,000 hours is the Lancaster number (probably without engines) and a He 177 would be nowhere near that. I’d say 25 a week max. I believe the Germans were hoping for 200/month at one point with all plants.

It seems that by shifting the He 177 workforce to V1 production the Luftwaffe achieves a capacity of about 16000 to 20000 missiles a month which is 16000 to 20000 tons a month.

How many 10000 ton raids could Bomber command run per month? Launching and transporting a V1 required manpower but I’m sure its nothing compared to training a bomber crew, maintaining airfield defences and a fighter force. It’s clear also the V1 was going to need improvements to improve its survivability.

However if V1 or V2 accuracy gets in the 1km range significant effects are likely to be achieved. Factor in improvements, such as a proximity fuse to airburst the missile (say near and airfield) the weapon starts to look disruptive.

The V2 looks not so bad compared to the V1 if explosives delivered are the metric as it achieved nearly 100% reliability in its final versions and couldn’t be shot down. Of course the V1 lead to the direct death of 70 RAF fighter pilots engaged in interception not including others lost in the attacks on V1 launch sites.

In terms of guidance the V1 was to receive the Ewald II or Ewald-Sauerkirsche midcourse guidance system with which about 2km accuracy. I doubt the little bit of electronics would have increased the cost of the V1 by much. Assume the electronics doubles the price of the autopilot and our missile now costs 470 hours to make not 350 but in return for that our accuracy is 2km. If it is desired to attack the towns around Castle Bromwich (spitfire factory) or Birmingham either a turbojet is required or the V1 warhead needs to be reduced to half a ton. I doubt the electronics would cost so much. Vacuum tubes were by now mass produced in automatic machinery.

Higher accuracy would be possible by guiding the V1 to impact but it was not desired.

In terms of the jet engine note that in post #94 that BMW were able to fabricate the entire turbine blade and disks of the BMW 003A2 in only 10 hours. German disposable turbines were supposed to operate on cooled steel blades at 650C. Noteworthy is that the Whittle engine on the Gloster Squirt flew at only 600C and that the Jumo and BMW turbine inlet temperature was about 770C.

Most V2 launched used the LEV-3 guidance system which used gyroscopes and an accelerometer to cut of the motor when the desired speed had been reached.

About 25% used a guidance beam that operated at boost similar to the ones used to guide bombers, it was only two dimensional and did not control the missile in the vertical plane. It was called Viktoria Leitstrahl. It reduced lateral dispersion (cross range) by 50%; A small percentage of these may have used a Doppler system to measure missile speed thereby replacing the accelerometer which improved down range accuracy by 10%

A system that had been worked upon for many years and tested was the zirkel system in which the V2 was to ride a pencil beam (beam riding) based on a 7m dish tilted up. The beam was conically scanned and the V2 could centre itself in the beam (many ways of coding positional data on the beam). Radar measured down range distance and Doppler missile speed giving all the parameters need for a complete cut off calculation. An electronic differentiator damped out the residual speed of the missile at cuttoff.
The system ran in to problems because of ground plane interference but the adoption of 9cm waves solved that. In this form the system was called vollzirkel. It was expected to achieve an accuracy of 500m and fulfil Werner von Brauns promis of 1 mill accuracy (ie 100m at 100km or 1 part in 1000).

One would expect quite a loss of accuracy as the missile tumbled during reentry but even assuming 1000m accuracy it is enough to attack airfields or major factories.

A System called SG-66 with a gimballed system of gyros and accelerometers was hoped to achieve the same accuracy. Highly accurate fluid bearings were under development. One U-boot received an inertial guidance system.

The Winged V2 (A4b) was expected to offer an unprecedented accuracy of 120m to 180m since it could be steered by secondary radar command through the stratosphere to the point it entered a terminal dive to target and disappeared below the radar horizon. Three giant Wassermann (Aquarious) height finding aerials were to be laid on their side to give 0.01 degree accuracy and 10m range accuracy.

The guided and unguided versions of the V1 and V2 could be mixed in with each other. For instance unguided V1 can acts as decoys for guided ones.


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## kool kitty89 (May 9, 2015)

Koopernic said:


> Because the V1 was a cheap weapon doesn’t mean It couldn’t be upgraded to an more expensive but much more accurate guided version and that this would mean the weapon was no longer worthwhile.
> 
> More range and accuracy widens the range of targets outside of the Greater London area and makes it possible to target large factories.


Indeed, a more costly weapon could still be more cost effective if the actual damage done (and utility of hitting precision targets) outweighed the added costs. (including time to operational service)

Granted, similar engineering could be applied to weapons systems with fairly complex or fairly simple (or no) guidance systems. One of my points about a turbojet powered cruise missile (even one using a 004B or simplified derivative) was the sheer cost of the V2 itself, and how much middleground there was between the V1 and V2 for unmanned weapons systems, including more advanced cruise misslies.



That said, the matter of a potentially even simpler V1 derivative weapon (and/or decoy drone) might have been practical to employ even sooner, perhaps in time for use late in the Blitz. (or maybe even the BoB) Pulse jets have vibration issues, but the lack of torque should still help somewhat for very simple guided (or just straight flying balanced/trimmed unguided) drones/missiles.

Though it may have been possible for the RAF to distinguish between drones/missiles and formations or streams of bombers/fighter bombers not just by size, altitude and formation pattern, but by use of the older acoustic warning system. (given how loud pulse jets are, and the low pulsing frequency, it would be easy to tell them apart from piston aircraft, and they'd be detected sooner due to the sheer noise levels. (closer to the range radar was effective)

Turbojet drones would be much quieter, but more costly/complex. Using groups of smaller pulse jets would be somewhat quieter and higher frequency (and quieter if any sort of muffling was used -also thrust augmentation). Ramjets would be quiet too, if they'd invested more in investigating simple, throw-away, low performance ramjets. (though pulse jets and ram jets would be useful in more applications than just drones/missiles, and the static thrust of pulse jets makes them potentially useful for JATO purposes, and much research going into disposable engines would still apply to their longer-life counterparts as well -at least in terms of turbojets and ramjets, but also valveless pulsejets or valves lasting long enough to at least be reliable for typical length sorties)




> The Arado works in Late 1943 employed 16,000 people in production of the Heinkel He 177 while a large number were likely at Heinkels own facility. If 16000 people worked a 48 hour week they produced 768,000 hours. This could produce in 1 week:
> 1 2,194 V1’s at 350 hours each. (I fact about a production rate of 10,000 month is what seems to have been available)
> 2 192 V2 missiles at 4000 hours each (the figure for the 10,000th produced)
> 3 38.4 He 177 at 20,000 hours each. In fact the 20,000 hours is the Lancaster number (probably without engines) and a He 177 would be nowhere near that. I’d say 25 a week max. I believe the Germans were hoping for 200/month at one point with all plants.


Those figures would be even more comparable if Heinkel had put the engineering AND manufacturing resources of the He 177 into an earlier jet bomber project. Or, aside from engineering resources in the intellectual end, there's the cost of prototypes and preproduction aircraft too. Having more than just the He 280 on the table using Heinkel jet engines would have given the RLM much more reason to support them too, especially with an early-war offensive weapon design. (plus, even with Heinkel/Ohain seeing the HeS 6 as too bulky and heavy to be really attractive to develop further -an error in itself, but for the sake of argument sticking with that point of view- those drawbacks would be less significant on a larger aircraft where the engine weight and drag took up a smaller percentage of the overall aircraft)


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## GrauGeist (May 9, 2015)

The Air Ministry was approached in 1934 about a pulsejet powered flying bomb, so the potential was already there.

The problem was that the development of the engine itself was still in it's early stages. Add to that, the ideal placement of the engine for optimum performance hadn't yet been refined (the early design saw the pulsejet embedded in the fuselage) and finally, the technology behind the guidance system had yet to be developed to the point where reasonable accuracy could be expected.


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## stona (May 10, 2015)

I think it is worth considering whether any version of a V-1, however powered, was a sensible use of resources. They were so inaccurate as to be nothing more than an indiscriminate 'terror' weapon. Whilst the Nazis' political will to inflict some sort of vengeance on their Anglo-American tormentors might be understandable the V-1 adopted a tactic which had already been shown to be redundant. Scattering bombs over a city, even at the concentrations achieved on London, conventionally, during the 57 nights of the blitz did nothing to break the British will to continue. The conventional devastation of Germany's cities never compelled the Germans to give up, it did force many Germans to the realiseation that the war was a lost cause, but that is not the same thing.

Any kind of precision unmanned weapon was beyond the technology of the time. This was a weapon system that would have been worth developing, but it was decades in the future.

Cheers

Steve


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## tomo pauk (May 10, 2015)

The Germans and Americans were using guided weapons in ww2. The guided projectile that would home on a source of radio waves was a possibility.


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## stona (May 10, 2015)

tomo pauk said:


> The Germans and Americans were using guided weapons in ww2. The guided projectile that would home on a source of radio waves was a possibility.



A possibility? Maybe, but none was developed and the first missiles or unmanned aircraft capable of engaging precision targets at ranges comparable to those envisioned for a V-1 substitute were, as I said, not deployed for many years.

I guess accuracy wasn't so much of an issue if you are launching a nuclear warhead, but then the Germans were many, many years away from that too.

Cheers

Steve


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## tomo pauk (May 10, 2015)

When one of engineers in General Electric IIRC was asked 'why didn't you come out with jet engines years before the Germans; after all you were producing all kinds of compressors and turbines prior between the wars', he answered 'because it didn't dawned on us'. Or - it took many years for swept wings to take hold. So IMO it was one of the things that it was out there for the people to connect the dots. Like the British and Americans developing, producing and use of VT fuses, but Germany and SU did not in ww2 (apart from experimental stuff). Or APDS, or some countries neglecting the radars for many years.


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## Koopernic (May 10, 2015)

I don't get the claim that high precision wasn't a possibility. The electronics of the day could be extraordinarily accurate.

The Blind bombing systems merely need to be applied to the autopilot directly. It was only a matter of time.

For instance a Seetakt radar (land based version) could measure the range of a target out to 60km with only a 10m error. There was no 'percentage error' this was an absolute error. The reason was that the pulse was also sent down a series of switched delay lines which were precisely calibrated and then compared to the return pulse with a sort of Geneva mechanism or resolver. If you used two radars you could triangulate a target to within 10m. This is GPS scale accuracy.

This is what Oboe did. There are broadly two types of radar, primary which relies of a reflected wave of the target and secondary which relies on a transponder which upon receiving a radar pulse retransmits it on a different frequency, thus achieving greater range. A little bit of data can be appended such as IFF (Identification Friend or Foe) or some height information.

Oboes accuracy was sometimes exaggerated but if operating say 50km from the transmitter it was extremely accurate. This is often quoted as 17 yards. This is not the accuracy but the resolution that was used to inform the pilot if he was of path (by a Morse signal) Naturally at 100s of km of range the bomb would be released at maybe 10000m and subject to the effects of wind as it fell. There would be a little distortion due to the atmosphere, which was actually taken into account.

Bind bombing systems + auto pilot = an extremely accurate guided missile.

The USN did fly TV guided drones in the dying days of the pacific.

The Germans did fly TV guided versions of the Hs 293 (the so called Hs 293D) which had TV guidance in the nose. The TV transmitter was called Tonne Seedorf. it worked fine in the summer or good light conditions and Ive seen photographs of its black and white screen being test flown. Its not inconceivable that a jet powered V1 could carry an rotating directional antenna that could relay TV signals to a control aircraft.

The Germans had two radiation homing warheads Radischein and MAX-P as well as some work on infrared homming (seen as usefull against blast furnaces.


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## stona (May 10, 2015)

If it was possible then it must have been deemed either impractical, for whatever reason, or undesirable by the Germans. Is there another explanation as to why neither they, nor anyone else, deployed such a system at the time or even medium future?

Cheers

Steve


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## GrauGeist (May 10, 2015)

The TDR-1 used in the Pacific during WWII required a TBM-1C to guide it. Out of the 195 TDR aircraft built, only 50 were deployed and out of that 50, only 31 missions were successful.

Looking at the TDR project's development, you'll find that the guidance system was problematic and held up the project. While they had been working on the project for a while, it wasn't until 1942 that a first test flight was conducted, yet it was two more years before the system performed well enough that the TDR was able to go into combat.

So again, it was the developing technology that was holding the concept back: both the Radar Altimeter and the Television Guidance System.

Otherwise, it was a sound idea and capable of delivering a bombload of up to 2,000 pounds (910 kg). However, if the TDR were used by the Germans against Britain, it would have never stood a chance, as it's average speed was 140 mph (225 kph) and would be easily intercepted or downed by AA.


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## Koopernic (May 10, 2015)

The systems that would get a V1 or V2 accurate to say within 1km were testing and had been testing since 1943. The guidance beams had a problem with ground plane interference and the missile needed to damp out sideways velocities, it being no good placing a V2 to within 10m of a guidance beam if upon motor cut off it had a residual sideways velocity. Because development had been started fairly early the two problems had been identified and it seems solved: one by using microwaves and the other by electronic differentiation and correct 'damping equations'

The winged A4b did undertake two flights of which one displayed a successful re-entry before telemetry from the Minerva system indicated that the wings broke of at the root due aero thermal heating that was harsher than expected. The giant guidance system to control it to within just over 100m was also under development. It was called 'Wasserspiegel" or water mirror. It was made up of a existing radar systems rather than any new development.

It would be only a matter of time after the TV guidance systems developed for the Hs 293 anti shipping missile were tried on something like the V1. The Iconoscopes of the day had quite a problem in dim conditions but the war seems to have progressed them.

I suggest that the reason these systems didn't see service sooner was a primarily a conceptual one. Humans were thinking inside the box. The other was that the technology, such as radar, had only just become available in the mid 30s.

For instance the Miles Hoop-La, Britain's own fly back cruise missile, was rejected because it wasn't accurate enough to avoid killing women and children and so was 'beneath contempt'. That's actually the wording in the official document. The V1 is a latter aircraft than the Hoop-La, by then the gloves were off.

Ju 88 pilots on torpedo runs had a habit of entering the aircraft into a descent held by the quite good 3 dimensional autopilots the Luftwaffe had. They noted how accurate the aircraft was. This lead to the idea of using unnamed aircraft as giant missiles with oversized hollow charge warheads. (they were quite capable of smashing through a dam wall). The autopilot could be controlled via the kehl strassberg system used in the Hs 293 and Fritz-X though it was likely never used as the autopilot was quite accurate.


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## stona (May 11, 2015)

Koopernic said:


> Ju 88 pilots on torpedo runs had a habit of entering the aircraft into a descent held by the quite good 3 dimensional autopilots the Luftwaffe had. They noted how accurate the aircraft was. This lead to the idea of using unnamed aircraft as giant missiles with oversized hollow charge warheads.



The system was used on 'Mistel' composite aircraft and proved thoroughly unreliable and inaccurate. The Germans persevered with the system and at least one RN vessel was badly damaged by a near miss. The vast majority of launches, both test and operational, failed dismally.

There's a Mistel thread somewhere here in which I posted quite a bit of data to which I don't have access at the moment.

Cheers

Steve


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## GrauGeist (May 11, 2015)

Koopernic said:


> I suggest that the reason these systems didn't see service sooner was a primarily a conceptual one. Humans were thinking inside the box.


However, the concept had been in practice since WWI...how much longer would it take for the system to be perfected?

The Kettering Bug was proved to be a fairly accurate weapon in 1918, using rudimentary guidance systems of the time. It had a range of 75 miles (121 km) and an average speed of 50 mph (80 kph)...this was 20 years before the V1.

20 years is a long time when looking at the advancement of technology.


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## Koopernic (May 11, 2015)

stona said:


> The system was used on 'Mistel' composite aircraft and proved thoroughly unreliable and inaccurate. The Germans persevered with the system and at least one RN vessel was badly damaged by a near miss. The vast majority of launches, both test and operational, failed dismally.
> 
> There's a Mistel thread somewhere here in which I posted quite a bit of data to which I don't have access at the moment.
> 
> ...



Their lack of success can be attributed to their being used in the face of a phenomenal scale of allied air power and return fire power from shipping that they faced during the Normandy landings. If used against a surprise target, such as a dam face, as they had been designed for they likely would have been capable of prevailing against the lessor defences.

The point I was making was that an autopilot was already quite accurate on its own. Trimming in commands either from a radar navigation or a command guidance system allowed pin point accuracy to be achieved.


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## Koopernic (May 11, 2015)

GrauGeist said:


> However, the concept had been in practice since WWI...how much longer would it take for the system to be perfected?
> 
> The Kettering Bug was proved to be a fairly accurate weapon in 1918, using rudimentary guidance systems of the time. It had a range of 75 miles (121 km) and an average speed of 50 mph (80 kph)...this was 20 years before the V1.
> 
> 20 years is a long time when looking at the advancement of technology.



The vacuum tube had only been invented a few years before WW1. It took barely 20 years till the 1930s for that technology to mature enough to allow radar, TV, radio and radio control, electronic navigation, power servo controls, analogue computation. The V2 for instance used an analogue computer liked to electrohydraulic vanes. It was the only system fast and vibration resistant enough to stabilise the missile.

There were several German WW1 attemps at radio and wire controlled air dropped torpedos and glide bombs. There were to be flown from Zeppelins or large aircraft.

They were truly guided, unlike the Kettering bug which really would have been only about killing civilians.


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## tyrodtom (May 11, 2015)

And using Zeppelins had nothing to do with killing civilians ???


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## GrauGeist (May 11, 2015)

I have to point out, especially in WWI, that there were very few civilians in the trenches and fortresses where the Bug was intended to be used.

The guidance system aboard the Bug may have been crude by today's standards, but it was effective enough to measure it's flight.

Saying the Bug was only about killing civilians can be applied to every single piece of military hardware in history: from the longbow to the ICBM...


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## tyrodtom (May 11, 2015)

I wonder how many German civilians there were within 75 miles of the WW1 front lines?


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## stona (May 11, 2015)

Koopernic said:


> Their lack of success can be attributed to their being used in the face of a phenomenal scale of allied air power and return fire power from shipping that they faced during the Normandy landings. If used against a surprise target, such as a dam face, as they had been designed for they likely would have been capable of prevailing against the lessor defences.



No. Simply not the case as evidenced by the history of testing and operations for the 'Beethoven Gerat'. I recommend Robert Forsyth's _'MISTEL German Composite Aircraft and Operations 1942-1945'_ for a very good over view. The systems were not accurate or reliable. Even during completely unopposed testing the only thing they did consistently was fail to hit the intended target, they rarely came close.

I think you are applying 21st century hindsight to difficult, troublesome and for their time advanced mid 20th century technologies. The potential was certainly there but neither the Germans, nor anybody else, managed to realise it during WW2.

Incidentally they were not designed as dam busters. The guts of the war head was known as the SHL (Schwere Hohlladung) 3500. It contained 1,700 Kg of explosives. It was designed to pierce the armoured steel of battleships or blow open reinforced concrete targets. The easiest way to distinguish the variants is by the length of the so called 'elephant nose' extending from the front of the war head. Of course some dams would be a reinforced concrete structure and may well have been a target, just like bridges, bunkers etc.

Cheers

Steve


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## Shortround6 (May 11, 2015)

I am still trying to figure out _when_ vacuum tube technology reached it's zenith and ALL radars, guidance systems, auto-pilots and the like just staggered along from this zenith sometime in WW II until the transistor took over in the 1950s, over a decade later. 

All those vacuum tube radars and fire control systems in F-86Ds, F-94s and F-89s could have built at any time in late WW II right ??????


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## Koopernic (May 12, 2015)

GrauGeist said:


> I have to point out, especially in WWI, that there were very few civilians in the trenches and fortresses where the Bug was intended to be used.



You think that thing could hit within a kilometre of a trench when an artillery shell could barely do so? This weapon could do only one thing, indiscriminately be used against inhabitants of cities.


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## GrauGeist (May 12, 2015)

Koopernic said:


> You think that thing could hit within a kilometre of a trench when an artillery shell could barely do so? *This weapon could do only one thing, indiscriminately be used against inhabitants of cities.*


I find that a little disturbing...really.

It's sole purpose was to reach into defended space and strike a reinforced target with a much heavier payload (180 lb - 82 kg) than was capable at the time, either by air or by artillery. 

It's sole purpose of "indiscriminately be used against inhabitants of cities" is utter bullsh!t...it's wasn't the Paris gun, it wasn't a Zepplin taskforce, it wasn't Mustard gas - it was a proposed solution to strike fortified enemy positions within the entrenched battlefield in the hopes of creating a "breakout".

Reaching into defended space by artillery requires an increase in trajectory incline, which means the shells are falling on top of the fortified positions...this was designed to strike low on the enemy's position on one large "punch".

Just a recap: it was not designed to strike towns or cities, it was not designed to strike farms or villages. It was designed to impact fortifications...and suprisingly enough, very few civilians could be found in fortifications along the layers of trenches during WWI...most often, the people found within these areas were: soldiers!


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## Koopernic (May 12, 2015)

I repeat: "The point I was making was that an autopilot was already quite accurate on its own. *Trimming in commands either from a radar navigation or a command guidance system allowed pin point accuracy to be achieved*."

IE auto pilot plus radar and remote control technology = precision guided weapon.

The Misteln were to be involved in operation Eisenhammer: a plan to knock out soviet hydroelectric production near key areas of the weapons industry that was expected to cut Soviet weapons production by around 2/3rds.

There was provision to guide the aircraft by remote control via the autopilot in a similar manner to the Hs 293 anti shipping missile.

Below is a photograph of an indicator dial used on the Nachtfee system which transmitted commands for the EGON blind bombing system. As you can see the dial could give dozens of commands to the pilot or bombardier/observer. It could just as easily be used to trim in a heading to an autopilot. This system couldn't be fooled or spoof as it was coherent and unless the jammer was in exactly the same location, within meters, any spoofing attempts would fail.


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## kool kitty89 (May 14, 2015)

tomo pauk said:


> When one of engineers in General Electric IIRC was asked 'why didn't you come out with jet engines years before the Germans; after all you were producing all kinds of compressors and turbines prior between the wars', he answered 'because it didn't dawned on us'. Or - it took many years for swept wings to take hold. So IMO it was one of the things that it was out there for the people to connect the dots. Like the British and Americans developing, producing and use of VT fuses, but Germany and SU did not in ww2 (apart from experimental stuff). Or APDS, or some countries neglecting the radars for many years.


I rather doubt that turbojet propulsion hadn't occurred to at least some GE engineering staff during the 1930s, if not early, but the issue would be having the ambition and belief that such technology was worthwhile and gaining funding/support for such a project. Without competition developing similar designs and without direct interest from the government, such projects might not be all that forthcoming. As it was, GE's supercharger designs during the 1920s and 30s had been pretty poor and lacking in development, at least until other manufacturers started taking such development upon themselves. (Wright, P&W, among others working on independent supercharger designs due to GE's lacking performance)

Part of GE's early success with the I-16 and I-40 (J31 and J33) was due to using Rolls Royce supercharger designs/experience along with the extensive combustion chamber development Powerjets had undertaken. (that being one of the critical limiting factors -functional, stable combustion) They also had issues with turbine efficiency and the initial I-A engines failed to meet the specified thrust, managing only around 800 lbf each rather than the anticipated 1250, and only after further modification based on copying more of Whittle/Rolls Royce's turbine modifications did those prototype engines finally hit the 1400 lbf thrust range, similar to Whittle's W.1A.

The only actual Jet Engine project being seriously undertaken in the US prior to WWII that I'm aware of is Nathan Price's Lockheed L-1000 design (later J37) and that was both impractically complicated and underfunded. (a more conservative direct followon to his preceding centrifugal compressor steam turbine aircraft engine into the turbojet concept may have been a good deal more practical and timely in development) Apparently it wasn't very widely publicized or promoted either, given the apparent ignorance of the rest of the aircraft industry of those attempted developments at Lockheed.



That said, I do agree on the point about many technological developments being limited by sheer random chance discoveries and connections made between ideas or lack thereof. Missing the potential of relatively simple and straightforward concept (or less simple but already documented and published -it not patented) is all quite possible. That's almost certainly the reason Jumo had working, practical flame cans fairly early in their engine development while other struggled for years working out the combustion problem. (yet Jumo ended up held back primarily by vibration issues) Heinkel/Ohain adopted hydrogen fuel to accelerate initial testing to sidestep the combustion problem entirely and then later adopted a simple fuel vaporization system based on a gasoline/kerosene blow torch when attempts at atomizing fuel injectors were lagging. Ohain adopted a radial turbine to make initial testing and development easier as well, something no one else seems to have attempted.

The same issues might might apply to the lack of thrust augmentor ducting or cowling applied to pulse jets or ramjets, and certainly would apply to a great deal of electronic tech.

Sometimes those ideas do actually meet but end up held back by political or bureaucratic issues or other failures to cooperate.


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## kool kitty89 (May 14, 2015)

GrauGeist said:


> The Air Ministry was approached in 1934 about a pulsejet powered flying bomb, so the potential was already there.
> 
> The problem was that the development of the engine itself was still in it's early stages. Add to that, the ideal placement of the engine for optimum performance hadn't yet been refined (the early design saw the pulsejet embedded in the fuselage) and finally, the technology behind the guidance system had yet to be developed to the point where reasonable accuracy could be expected.


Limited emphasis on pulse jet engine development in general certainly appears to have been a major limiting factor, not just for the V1, but for a variety of other potential applications. Even starting in 1934, there was a great deal of potential rapid development for that form of propulsion, both valved and valveless. There'd already been a great deal of research done into the concepts and related mechanisms (including aerodynamic valves) prior to that time, though I'm not sure how much of it was publicly available (NACA research at least would be, including cowling and thrust augmentation that would be applicable to pulse jets, ram jets, rockets, and turbojets -thrust augmentation using ducts in the exhaust stream to combine high volumes of air to increase working mass would have been especially useful for low-speed applications like JATO, but certainly would apply to the speed ranges the V1 was employing and like Me 163 as well -though at higher speeds, using ducting specifically designed to efficiently take advantage of ram effect would be more useful for given weight and drag added; the simplest form of augmentation would literally just be attaching a duct similar to a townend ring aft of the jet/rocket exhaust nozzle, somewhat larger diameter than the exhaust stream itself, and leaving an air gap between).

Pulse jets are incredibly simple mechanically, but tend to require a great deal of trial and error in development and a lot of theory breaks down in practice, at lest from the articles I've read on development. (this is true for almost any engineering effort, but it appears a far more long-lasting problem not easily solved by more modern developments in science and engineering aside from the advent of computer modeling to partially supplant physical prototyping) In any case, the best development strategy tends to be just shotgun engineering: building as much variety of test designs as you can imagine, even some that don't seem sensible or are totally random, test them all and build on the observations.

The simplicity and materials/fuels practical to work with (especially with valveless designs) make it possible for pulse jets to have been developed to great extent decades earlier than they were without any other technological advances (existing late 1800s or early 1900s metalurgy, riveting, welding and brazing techniques, fuels, ignition methods, among other things, especially if using a fuel feed system as simple as a the pressure vessels used in contemporary blow-lamps). The greater problem is actual need/demand for such engines, and given their inefficiency and the advent of piston engine driven propellers in the early 1900s, the main applications would tend to be novelty/toy/model use and military drones.






Shortround6 said:


> I am still trying to figure out _when_ vacuum tube technology reached it's zenith and ALL radars, guidance systems, auto-pilots and the like just staggered along from this zenith sometime in WW II until the transistor took over in the 1950s, over a decade later.
> 
> All those vacuum tube radars and fire control systems in F-86Ds, F-94s and F-89s could have built at any time in late WW II right ??????


Even if you had the circuit design down for more advanced electronics, the vacuum tube technology itself was still a good bit more limited in the 1940s in terms of physical size, energy consumption, longevity, durability, etc. And even ignoring manufacturing costs, that all means bulkier, heavier, less reliable systems that require more power. (all of that is also part of the reason I suggested a larger cruise missile than the V1 itself might have been required to make adding more electronics viable, let alone cost effective -one could argue the added precision alone could more than make up the cost difference, but with the bulk/weight needed for electronics and possibly power supplies, it seems more plausible that increasing the warhead size would be significant as well -aside from potential of delivering far more deadly chemical or biological weapons, or perhaps shifting to incendiary bombs -the latter seems the most likely to actually be deployed)

Vacuum tube technology was improving and refining at very least well into the late 1960s, and aside from some military applications retaining their use due to potential redundancy or even on primary systems better hardened against electromagnetic damage, there was a great deal of use in consumer applications with more compact and cost reduced electronics. Not to mention, some tube based electronics were MORE compact and lighter (as well as cheaper) than their transistor counterparts for a time. Lots of oddities on the consumer market of the late 60s and early 70s. (GE's compact luggable Porta-Color television line comes to mind in particular, produced from 1966 to 1980 and surviving several attempts at solid state replacements due both to cost and weight).


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## GrauGeist (May 14, 2015)

In regards to vacuum tube technology of the early to mid 1940's, look at the TDR's TV camera that's mounted in it's nose here: http://www.ww2aircraft.net/forum/aviation/drone-warfare-40838.html#post1126561

Just the TV camera's diameter is greater than that of the V1's fuselage.


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## kool kitty89 (May 15, 2015)

GrauGeist said:


> However, the concept had been in practice since WWI...how much longer would it take for the system to be perfected?
> 
> The Kettering Bug was proved to be a fairly accurate weapon in 1918, using rudimentary guidance systems of the time. It had a range of 75 miles (121 km) and an average speed of 50 mph (80 kph)...this was 20 years before the V1.
> 
> 20 years is a long time when looking at the advancement of technology.





GrauGeist said:


> The guidance system aboard the Bug may have been crude by today's standards, but it was effective enough to measure it's flight.


Given the Bug used a rudimentary gyroscope stabilized autopilot system, it might not have been all that much simpler than a V1 (aside from the engine -the 4 cylinder piston engine is obviously more complex). Plus it had to deal with torque from the propeller, though not the level of vibration the As 014 produced.

The technology for simple unmanned drones and cruise missiles was obviously there much earlier than the operational V1, and aside from development interest and funding the matter of costs of production to value as a weapon (or drone, etc) would still be significant. (pulse jet vibrations are also a lot easier to cope with at smaller scales with much higher frequency pulsing -significant for smaller scale drones or even deployable weapons, or possibly used in batteries in leu of single larger engines)

Further, the intended purpose of the Bug is a bit closer to my earlier suggestion of a scaled down V1 better suited for tactical use and easier to launch from mobile platforms.

And of course, for decoy drones, you wouldn't need (or want) speeds nearly as high as the V1 offered. Mimicking fighter or bomber flight speeds and overall radar signature (within the limitations of radar of the day) would mean drones cruising closer to 200 mph.




GrauGeist said:


> In regards to vacuum tube technology of the early to mid 1940's, look at the TDR's TV camera that's mounted in it's nose here: http://www.ww2aircraft.net/forum/aviation/drone-warfare-40838.html#post1126561


Thanks for linking that thread. I'd overlooked some of the the unmanned drones already flying pre-war, particularly that Argus As 292.


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## Koopernic (May 15, 2015)

Vacuum tube technology reached a very high level just prior to WW2 and in particular during it. Automated mass produced Vacuum tubes between the size of a mans thumb and a ladies pinkie became standard devices. Some were highly economical; having pressed glass bases through which the conductors passed. They were reliable too 50,000 hours was not uncommon in a specified on/off cycle. Other's had steel housings and could handle a great deal of vibration. Steel envelop tubes were used for the analogue computer autopilot on the V2 because of their toughness. The reason a electronic computer had to be used was both the great speed of the electronics but the vibration resistance which disrupted mechanical computing devices. There were of course highly specialised micro tubes that handled the acceleration of a gun launch that were fitted into artillery ammunition.

Certain specialised tubes, such as those generating high output powers for radars had shorter lives.

There were very few advances after WW2 and most of those were in specialised areas.
1 Video Recording Tubes became more light sensitive with Videocon taking over from ikonoscopes.
2 Besides Magnetrons high power Klystrons and Travelling Wave Tubes allowed sophisticated microwave radar and overcame the limitations of magnetrons.

Vacuum tubes developed only slightly: by identifying chromium contamination in the tungsten filaments of vacuum tubes the computers that operated the NORAAD and SAGE (Semi Automatic Ground Environment) achieved 500,000 hour life which gave the reliability to allow digital computers for dispatching F101 and F106 to intercept possibly threatening nuclear carrying bombers.

Printed Circuit Boards were used by both sides, the Germans used ceramic ones. Ideas such as terminal blocks came in.

These advances were not necessary for the kinds of tubes required for automatic control of a missile.

The relatively reliable miniature vacuum tubes made many more devices practical. It was more up to engineers to come up with a conceptual frame work for creating circuits and circuit building blocks and to realise those.

German aircraft in 1940 could carry radar altimeters, blind approach systems (FuBL) and fully automatic landings had been carried out. Auto track radar came in both German and US radar in 1943.


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## stona (May 15, 2015)

And the guidance system as used in the Mistel aircraft simply didn't work. They struggled to hit a cliff face in early testing, and were no better when used operationally. They, or rather the warheads, were not designed specifically for use against dams either. Operational attempts were made on a variety of targets including dams and ships with precisely zero success, unless you count the near miss on HMS Nith. She may not even have been the intended target!

'Eisenhammer' never happened and other attempts against various Soviet targets on the Eastern front were as unsuccessful as those against the Allied bridgehead and Mulberry harbours in Normandy.

You are talking up a system which might look good on paper, but forced prematurely into operation,as were many late war German developments, it proved a very expensive failure.

Cheers

Steve


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## davparlr (May 19, 2015)

With one plane and one bomb, very precise accuracy would be required. The technology did not exist in WW2, except possibly remote control TV guided weapons. None of other systems would have provided the accuracy. Rf guidance was susceptible to countermeasures, and the Brits were good at it. Inertial nav capability was no where near good enough. In the 70s INSs drifted at a mile an hour. If any beam system would have worked, they would have been used in Vietnam and many crew could have been saved, but, they weren't. The TV remote guided Bullpup was marginally effective, but not until TV guided and laser guided weapon became available did one bomb one hit became possible and even then spotter aircraft was needed. In the 1980s, the B-2 was tasked with very precise autonomous dumb bomb drops (yes even nuclear bombs sometimes need to be precisely delivered). In order to achieve this accuracy, a highly precise INS system actively updated by a stellar inertial system and a high resolution radar update capability was required. None of these systems existed prior to the 80s, much less WW2. The Germans were never going to have a precise V-1 system. Now if they had cancelled the He 177 and built another 9000 V-1s, this would certainly have shaken up Britain and occupied a lot of military defense. Still wouldh't have changed the war.


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## kool kitty89 (May 20, 2015)

Another thought that hasn't come up is using animals onboard for guidance, like American researchers did with trained pigeons targeting specific target shapes/patterns on the horizon. It worked for shipping, so possibly could work for cities as well?

Probably something pulse jets would prevent due to noise and vibration. Turbojets, ramjets, and rockets would work, though.

For that matter, I wonder if that would work for anti aircraft missiles, with birds trained to target bomber formations.


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