Turbojet powered cruise missiles

[Koopernic]

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.

 

[GrauGeist]

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

 

[Koopernic]

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

 

[stona]

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

 

[GrauGeist]

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.

 

[stona]

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

 

[pbehn]

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.

 

[Shortround6]

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.

 

[kool kitty89]

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)

 

[GrauGeist]

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.

 

[kool kitty89]

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)

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

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

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.

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

 

[davparlr]

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.

 

[kool kitty89]

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.

 

[Koopernic]

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.

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.

 

[kool kitty89]

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)

 

[GrauGeist]

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.

 

[stona]

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

 

[tomo pauk]

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.

 

[stona]

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

 

[tomo pauk]

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.