Ju388 any good?

[kool kitty89]

The Ju 288 have had no connection with Ju 88/188/388 (apart from the company that was to design produce it, of course) - the fuselage was designed around a bomb bay and space for fuel tanks, the wing was new, pilot's cabin was new, as was the engine and armament. The engine was the main problem, Ju 288 won't work well without 2 x 2000 HP engines as designed, but the initial, smallish prototypes might prove a better base for DB 603-powered bombers than the Do 217.

I suppose the Do 217's lead in development timing is mitigated by the late arrival of the DB 603 as well (and even if its development hadn't been halted early war, the Ju 288 might have progressed quickly enough to still be attractive, had it targeted that engine from the start).

Then again, if Bramo's 2000 hp class 329 had continued development beyond 1938, it may have made for a more capable radial engined Do 217 and better matched to the airframe than either the 801 or 603. (granted, those may also have matched well to the initial smaller Ju 288, but likely able to enter production sooner)

 

[GregP]

I know it moves around, but I see absolutely no merrit in saying very high altitude bombing would work over the UK in WWII due to lack of the same jetstream that was over Japan.

Very high altitude bombing didn't work very well all over the rest of Europe and bombing was never that accurate from 30,000+ feet up. If you area-bombed, you could probably do a lot of general damage, but precision bombing doesn't seem like it was really all that precision. If it was, they would not have had to visit the same target over and over to take out a partitular factory.

Very high-altitude bombing over the UK would have been no more and no less effective than anywhere else in Europe. And if the Germans had bombed accurately via radar aiming, it would have worked for the Allies, too. It never worked all that well during WWII and even after, until the technology caught up with the weapons. When it did, it was in the form of guided munitions, not accurate bombing from 30,000+ feet.

As late as Viet Nam if you wanted to hit somethign positively, you sent in some strike fighters at low altitude with retarded bombs. You didn't send in B-52s from 60,000 feet with gravity bombs. The B-52s carpet-bombed things like the Ho Chi Minh Trail ... not individual factories or warehouses. If you fly along a road, it isn't too hard to mostly hit the road with bombs. Hitting a single small bridge is another task entirely.

It would have been no different in WWII over London. They didn't have some magic aiming device ... they had optical bombsights that were as flawed as ours were.

 

[Koopernic]

North Atlantic Jetstream forecast for June

Jetstream Forecast - Jetstream Map Updated Four Times Daily - Netweather.tv

Nice, not much of if over Southern England though?

Luise Brown in "Radar, Technical and Military Imperatives" gives the accuracy of Oboe, as measured in practical use, at 350 meters. Brown is comparing between the various methods of bombing and doesn't quote circumstances though I'm assuming this is roughly at the limit of its range say 500km and from around 10,000m altitude and isn't just the cumulative effect of bombing at marker bombs. Operated over closer targets and released from lower altitudes over the Ruhr it could achieve 65m. It was 22 times more accurate than H2S/H2X (irrespective of whether 3cm or 9cm) and in general better than visual bombing on a clear day. He gives the accuracy of H2S/H2X as 1.8km in the same paragraph. (I suspect that H2S could do much better if given a coastal/esturine target)

350m actually sounds quite poor and is an error vastly greater than the instrument error of Oboe. The errors are coming either from the fall time of the bomb, forced errors during combat or outiers from botched runs.

The 1942 version of Oboe was the most accurate and it would be fair to assume that a German 1944/1945 system would match it. EGON-II was a late 1944 or 1945 system, the earlier EGON used only one not two radars so the bearing range was limited by the angular resolution of a Freya based radar, up to 0.2 degree or 0.1 degrees at best. If one assumes Ruhr like ranges then 65m might be achievable, if one assumes bombing altitude is 1.5 times greater accuracy would be 2.25 times less (square law) ie about 150m.

 

[GregP]

Not much of it over southern England today. I've never seen a good jetstream map of the world in WWII because that's when widespread knowledge of it began ... but they had no way to accurately map it other than pilot reports, and combat ops were not dispatched to chart weather phenomena.

 

[SpicyJuan11]

I know it moves around, but I see absolutely no merrit in saying very high altitude bombing would work over the UK in WWII due to lack of the same jetstream that was over Japan.

Very high altitude bombing didn't work very well all over the rest of Europe and bombing was never that accurate from 30,000+ feet up. If you area-bombed, you could probably do a lot of general damage, but precision bombing doesn't seem like it was really all that precision. If it was, they would not have had to visit the same target over and over to take out a partitular factory.

Very high-altitude bombing over the UK would have been no more and no less effective than anywhere else in Europe. And if the Germans had bombed accurately via radar aiming, it would have worked for the Allies, too. It never worked all that well during WWII and even after, until the technology caught up with the weapons. When it did, it was in the form of guided munitions, not accurate bombing from 30,000+ feet.

As late as Viet Nam if you wanted to hit somethign positively, you sent in some strike fighters at low altitude with retarded bombs. You didn't send in B-52s from 60,000 feet with gravity bombs. The B-52s carpet-bombed things like the Ho Chi Minh Trail ... not individual factories or warehouses. If you fly along a road, it isn't too hard to mostly hit the road with bombs. Hitting a single small bridge is another task entirely.

It would have been no different in WWII over London. They didn't have some magic aiming device ... they had optical bombsights that were as flawed as ours were.

I'm gonna go out on a limb here, and I hope it doesn't snap, but wouldn't the Fritz X and Henschel 293/294 have been somewhat accurate assuming the Allies don't use counter-measures?

 

[Shortround6]

Not much of it over southern England today. I've never seen a good jetstream map of the world in WWII because that's when widespread knowledge of it began ... but they had no way to accurately map it other than pilot reports, and combat ops were not dispatched to chart weather phenomena.

Actually over or near Japan in 1944 they were.

"The 2d WRS, activated early in 1944, was sent to CBI, where its planes served XX Bomber Command and the Fourteenth Air Force in China and Eastern Air Command in Burma." and "The fourth weather recco squadron, the 655th Bombardment Squadron (H), went to the aid of XXI Bomber Command, whose B-29's on Saipan and Guam in late 1944 took over from XX Bomber Command the task of bombarding the Japanese homeland. Activated in August 1944 and fully in place by the following spring with an advanced echelon on Iwo Jima, the unit was redesignated the 55th Reconnaissance Squadron (VLR), Weather, in June 1945."

From; HyperWar: Army Air Forces in WWII: Volume VII: Services Around the World [Chapter 11]

It became common to send at last one "weather" recon plane in advance of the actual strike force/s.

 

[Shortround6]

They have two major problems for this type of work. They are visually guided, at the least the majority of the ones used in actual combat, Which means the missile controller has to be able to see both the missile and the target. These missiles were not dropped from high altitudes. Want to try tracking a flare in the tail of the bomb from 25,000ft or above? add in the higher you go the greater the chance of spotty clouds.
Now figure in the time needed for the bomb/missile to drop from 25,000ft or above while the plane takes NO evasive action or even changes course by much while the heavy AA guns fire at it.

Then we will throw in the electronic counter measures

As anti-ship weapons from medium altitudes they were ground breakers. AS a specialized weapon against certain ground targets (like a bridge) they may have have proved quite useful. As a general bombardment weapon or against a fixed location but camouflaged target their usefulness decreases. In some cases just the use of smoke generators can reduce the missile carrying aircraft to just dropping the bomb into the cloud and hoping.

 

[SpicyJuan11]

They have two major problems for this type of work. They are visually guided, at the least the majority of the ones used in actual combat, Which means the missile controller has to be able to see both the missile and the target. These missiles were not dropped from high altitudes. Want to try tracking a flare in the tail of the bomb from 25,000ft or above? add in the higher you go the greater the chance of spotty clouds.
Now figure in the time needed for the bomb/missile to drop from 25,000ft or above while the plane takes NO evasive action or even changes course by much while the heavy AA guns fire at it.

Then we will throw in the electronic counter measures

As anti-ship weapons from medium altitudes they were ground breakers. AS a specialized weapon against certain ground targets (like a bridge) they may have have proved quite useful. As a general bombardment weapon or against a fixed location but camouflaged target their usefulness decreases. In some cases just the use of smoke generators can reduce the missile carrying aircraft to just dropping the bomb into the cloud and hoping.

Great info (and commonsense ) as always Shortround! But could the Hs 293D work better?

 

[Koopernic]

Great info (and commonsense ) as always Shortround! But could the Hs 293D work better?

For those that don't know the Hs 293D was a variant of the rocket boosted glide bomb that incorporated a TV camera. This freed the launch aircraft to complete freedom of manoeuvre, to escape or hide in clouds, to turn around rather than follow a profile designed to line up the missile with then operator.

Obviously if someone had this technology it would be very useful if weather conditions permitted.

The TV camera and its TV monitor were called Tonne-Seedorf, I believe in their 4th and 3rd stages and essentially complete. IE Tonne 4, Seedorf 3. Some long haired technician in Germany I think has part of one.
The final versions achieved a high level of compactness and could cope with reasonable light conditions.(a big issue). It seems to have been ready for production by the end of 1944. It had been many years to miniaturise the units, the final variant had to be pressurised. Only two types of vacuum tube were used.

I'm sticking with the argument that radio guided bombing over the UK would be more accurate than visual bombing over Japan while acknowledging the issues of what could happen to the bomb due to cross and headwinds/tailwinds on the way down.

The 8 x 250kg bombs a Ju 388 could release were not a trivial matter.

The Fritz-X bomb was very accurate and reliable when it could be used. CEP's were in the 10s of meters and operational hit rates around 50%. Of course they needed to be dropped in good visual conditions, essentially cloudless days. That is possible in Europe but perhaps only say 30% of the time. The bomber made a relatively high speed run to target at around 22000ft and released the bomb according to the standard Lotfe 7 gyro stabilised computing drift correcting bomb sight.

The pilot immediately throttled back, lowered flaps and did a 2000ft pull-up manoeuvre and then restored level flying. This manoeuvre slowed the aircraft down and lined it up with the bomb. It also threw of the AAA predictors. The bomb aimer than lined up a flare with the target, very radical course changes could be made and so a manoeuvring battleship or cruiser was still vulnerable. A bridge made a nice target though the armour piercing nature of the bomb meant not much explosive was carried.

With better engines there surely was scope to increase the launch height since there needed to be a reserved to conduct the pull up manoeuvre. US aircraft using the AZON bomb didn't need a pull-up since the special sight meant the bombardiers could tracking behind then. Since azimuth only was being tracked the bomb didn't need to be lined up, you couldn't control down range. Americans also didn't always use the bomber to control the bomb and often used a higher flying P-38 with a bomb aimer in the nose. The Luftwaffe could copy this idea easily if it occurred to them.

Now as to jamming of the Kehl-Strasberg system.

The guidance system used on both the Friz-X and Hs 293 had the following salient points:
1 There were 16 frequencies
2 The 16 frequencies used in the Mediterranean were different from those in the Bay of Biscay in part because Chain Home used the same frequencies.
3 The missiles were capable of one in flight frequency change to evade jamming.

German sources generally deny that allied jamming worked. Even Martin Bollinger's recent book castes doubt upon this.

Early allied jamming attempts worked by detecting the frequency, the operator then slammed a module in place that jammed via noise. Dubious effectiveness and the jammers often jammed each other.
After some missiles had been captured in Foggia Italy the allied jamming switched to jamming all 16 frequencies at once with a 'spoof command' of hard right rudder (or similar) rather than noise jamming. Some German commentators have questioned its effectiveness due to the low transmitter power compared to the German transmitter.

The Germans tended to monitor jamming attempts and they didn't detect any, though this may be because the sniffer aircraft, a He 177, was shot down.

Had they detected jamming their course of action would have been as follows.
1 The antenna of both the aircraft and missile would be changed to ones designed for 3 times the wavelength. These had been stocked in advance.
2 The transmitters and receivers would be swapped out for modules with three times the wavelength. These had been stocked.

As a backup Hs 293A could be modified with wire spools added into the wing tips: all missiles from the 300th incorporated this modification.
The Fritz X could also use wire spools, the system wasn't stocked however and it was slightly different as the wire would have been shorter (about 10 instead of 14 km)

There was also an FM based system (Kehl Strasberg was AM) that was developed and tested but not produced as an alternative.
Late war German missile guidance would tend to use the Kogge-Bigge system, intended mainly for both AAM and SAM missiles. It used a 21cm wavelength, highly jam resistant impulse modulation, the rod aerials were directional and could take the place of the wire spools. They only listened to transmissions from 'behind' to reduce sensitivity to jamming attempts.

The Germans attempted non of these alternatives because they were not aware of effective Allied jamming.

The Toone Seedorf system had also been designed to be jam resistant.

TV signals have two oscillators: one to rest the frame oscillators and the other the oscillators that controls each line or retrace. To avoid jamming early versions of Tonne Seedorf used crystals in the TV camera-transmitter and Screen receiver which were so accurate the synchronisation signal did not have to be transmitted. This 'laboratory' scale accuracy was too great so they developed a way of embedding the synchronisation signals in the picture signal as low bandwith signals that kept a cheaper crystal in synch. This eliminated one method of jamming. There were more anti jamming techniques applied.

The Kehl-Strassbourg FuG 203/ FuG230 kehl strassberg system that was
used on Fritz-X and Hs 293

FuG 205/FuG 235 Greifwald/Kolber FM (frequency modulated) instead of
amplitude modulated system as drop in replacement backup for Kehl/
Strassberg in the event of significant jamming being detected.


FuG 510/FuG 540 Kogge/Brigge High Frequency 1200Mhz/21cm impulse
modulated using directional Polyrod antenna was to be the core of a
number of German guided missiles with development starting in 1944.
It was designed to be very immune to jamming due to the type of
modulation.

 

[GregP]

Hi Shortround,

They didn't send the weather planes to map the jetstream ... they sent them to look at the weather along the intended mission route. If they encountered high winds, these were relayed to the mission crew.

Mapping the jetstream was NOT on the agenda unless it affected the upconing mission. If they DID have jetsream issues, the sole purpose was to find a way to get around it or know not to launch, not map the airflow. The mission was the ONLY priority.

The real jetstream work started AFTER the war.

 

[Shortround6]

True but then when and if a particular flight noticed a really high speed airflow/wind it wasn't quite "It was all an estimate by a scared guy in the nose of a bomber who wasn't a meterorologist." It was a crew or mission looking for it in addition to other weather phenomenon (and this was their only duty) and reporting back to base meteorologist or meteorological section. They may not have had the ability to generate a real "map" but they knew something was going on or different than some other areas of the world.

 

[SpicyJuan11]

I don't mean to digress too much, but what was the point of the Ju 488? It didn't seem like too great of an a/c considering it could only carry 11,020 lbs at 2,795 miles (nothing compared to the B-29 or the He 277, it's contemporsries) albeit it had a decent service cieling and was pretty fast at a proposed 428 mph, and supposedly very easy and fast to build (due to its very high amount of parts commonality with other aircraft in service.

 

[Shortround6]

The last was it's main attraction, a fast, easy and cheap way to get a heavy bomber.

Since it never flew and the engines intended for it were, shall we say, problematical and somewhat resembling modern "vaporware" the estimated performance can only be regarded with a bit of skepticism.

 

[SpicyJuan11]

The last was it's main attraction, a fast, easy and cheap way to get a heavy bomber.

Since it never flew and the engines intended for it were, shall we say, problematical and somewhat resembling modern "vaporware" the estimated performance can only be regarded with a bit of skepticism.

But didn't the He 277 also share much part commonality with the He 177, also how was the Jumo 222 troublesome in 1944, when it was scheduled to enter production? I have the book Ju 288/388/488 with the performance data of the Ju 488 with BMW 801 TJ's, I'll take a look at what it says when I get a chance.

 

[Shortround6]

They built about 270-280 Ju 222s and yet around 1/2 dozen airfames ever flew with them. Couldn't get them to the air frame makers due to transport troubles? some maybe but NONE made it in 1944/45? Maybe the Bulk of them are still hiding in the secret antarctic base? Maybe even though they were built they weren't really airworthy and needed modifications? The last happened to several different countries. Airframe wise it happened to the HE 177. They started churing out the A-0 series with things still seriously wrong with the engine installation because they had pre-ordered parts/materials and tooling and had workers at the factories standing by with tooling and the parts. They were hoping for the quick fix later. For an engine example, Allison had to rework hundreds of early V-1710s at company expense in the long nose P-40s to get them up to the contracted power/durability in 1940/41. Engines were flown with boost and RPM limits until they could be shipped back to the factory. It happened.
Given the German penchant for cobbling together bits and pieces of guns, armoured vehicles and aircraft and of using prototypes on operations the idea that they had even 200 airworthy 2000hp engines sitting in a warehouse just waiting to be used and weren't used takes an awful lot of faith.

 

[SpicyJuan11]

They built about 270-280 Ju 222s and yet around 1/2 dozen airfames ever flew with them. Couldn't get them to the air frame makers due to transport troubles? some maybe but NONE made it in 1944/45? Maybe the Bulk of them are still hiding in the secret antarctic base? Maybe even though they were built they weren't really airworthy and needed modifications? The last happened to several different countries. Airframe wise it happened to the HE 177. They started churing out the A-0 series with things still seriously wrong with the engine installation because they had pre-ordered parts/materials and tooling and had workers at the factories standing by with tooling and the parts. They were hoping for the quick fix later. For an engine example, Allison had to rework hundreds of early V-1710s at company expense in the long nose P-40s to get them up to the contracted power/durability in 1940/41. Engines were flown with boost and RPM limits until they could be shipped back to the factory. It happened.
Given the German penchant for cobbling together bits and pieces of guns, armoured vehicles and aircraft and of using prototypes on operations the idea that they had even 200 airworthy 2000hp engines sitting in a warehouse just waiting to be used and weren't used takes an awful lot of faith.

Short, production was scheduled to take place in late 1944, but was then delayed to February of 1945, the worsening war situation prevented the start of mass production.

 

[SpicyJuan11]

They built about 270-280 Ju 222s and yet around 1/2 dozen airfames ever flew with them. Couldn't get them to the air frame makers due to transport troubles? some maybe but NONE made it in 1944/45? Maybe the Bulk of them are still hiding in the secret antarctic base? Maybe even though they were built they weren't really airworthy and needed modifications? The last happened to several different countries. Airframe wise it happened to the HE 177. They started churing out the A-0 series with things still seriously wrong with the engine installation because they had pre-ordered parts/materials and tooling and had workers at the factories standing by with tooling and the parts. They were hoping for the quick fix later. For an engine example, Allison had to rework hundreds of early V-1710s at company expense in the long nose P-40s to get them up to the contracted power/durability in 1940/41. Engines were flown with boost and RPM limits until they could be shipped back to the factory. It happened.
Given the German penchant for cobbling together bits and pieces of guns, armoured vehicles and aircraft and of using prototypes on operations the idea that they had even 200 airworthy 2000hp engines sitting in a warehouse just waiting to be used and weren't used takes an awful lot of faith.

Short, production was scheduled to take place in late 1944, but was then delayed to February of 1945, the worsening war situation prevented the start of mass production.

 

[Shortround6]

What do you call 270-280 engines? That is not tool room samples.

Granted the continual futzing about the the size of the cylinders needed additional test engines but P W is supposed to have gotten the R-4360 through initial testing and type testing with 23 engines compared to the 8 it used for the R-2800.

Even if they sucked up 80 test engines that leaves 200 that did nothing.

If they used up all 270-280 Ju 222s in testing I would suggest that this was a boondoggle of unprecedented proportions. P&W spending a mere 25 million dollars to develop the R-4360 for those 23 engines and associated engineering and testing.

I have yet to see a breakdown of how many of each model of the JU-222 were actually built.

 

[wiking85]

They built about 270-280 Ju 222s and yet around 1/2 dozen airfames ever flew with them. Couldn't get them to the air frame makers due to transport troubles? some maybe but NONE made it in 1944/45? Maybe the Bulk of them are still hiding in the secret antarctic base? Maybe even though they were built they weren't really airworthy and needed modifications? The last happened to several different countries. Airframe wise it happened to the HE 177. They started churing out the A-0 series with things still seriously wrong with the engine installation because they had pre-ordered parts/materials and tooling and had workers at the factories standing by with tooling and the parts. They were hoping for the quick fix later. For an engine example, Allison had to rework hundreds of early V-1710s at company expense in the long nose P-40s to get them up to the contracted power/durability in 1940/41. Engines were flown with boost and RPM limits until they could be shipped back to the factory. It happened.
Given the German penchant for cobbling together bits and pieces of guns, armoured vehicles and aircraft and of using prototypes on operations the idea that they had even 200 airworthy 2000hp engines sitting in a warehouse just waiting to be used and weren't used takes an awful lot of faith.

Part of the issue is that Dessau, where the prototypes were made and stored, was bombed in 1943 and repeatedly in 1944 making it very messy to get into production and probably destroyed a large number of units. Not only that, but the constantly spec changes forced a number of redesigns.

 

[Shortround6]

It could be that a number of completed units were destroyed. That may be the most logical explanation. What doesn't seem logical is that despite the bombings and problems in late war Germany that the bulk of the 290 Ju-222s would be the latest and greatest versions from the winter/spring of 1945.

There is a lot of conflicting information on this engine, sometimes books/websites on it contradict themselves and on things that should have been no-brainers. Like in Anthony Kay's "Junkers Aircraft Engines" where there are statements like;

"The Jumo 222E and F-series were designed as similar to the A and B-series but with a gear driven, two stage supercharger with and inter-cooler. The bore and stroke was less than the C/D series but capacity was increased."

And " Bore and stoke of the G and H models reverted to that of the A and B models but capacity was greatly increased".

Now the only way you can increase capacity while making the bore and stoke smaller is to add cylinders but no mention of that is made in the book.

Another source says doesn't list a Jumo 222 G/H but lists a Jumo 225 with the same bore and stroke as the 222 G/Hand the same capacity/displacement but says " A further development of the Jumo 222 by the addition of 12 cylinders arranged in 2 banks of 6 cylinders each." it also says "Stage of Development: Design stopped before completion."

The old Junkers home page says " Initial production series Jumo 222A-1 and B-1 were only built in few numbers A- and B-series differ in the airscrew ratio. " and "The production of the series I was stopped due to technical problems. The series II got a larger capacity and a modified ignition system As the problems still remained, the production of Jumo 222A-2 and B-2 again was stopped in late 1941."

The page reads like a "fair" translation from German. Not bad but not quite right.
Junkers Engines - Jumo 222

Note the chart lists the 222G/H at 69.6 liters which only works with the bore and stroke listed if you use 36 cylinders.

Also the C/D series should be 55.5 liters displacement and the E/F series should be 49.9 liters.

Anthony Kay's book has the same mistakes in displacement and also says that "production" started of the 222A-1 and 222B-1 in 1939 but was soon stopped due to ignition problems. production restarted with the 222A-2 and 222B-2 with redesigned ignition systems but the problem was not solved and production was stopped again in late 1941. I don't know who was coping who or if this is really the right story. No numbers are given of each type. 289 engines is too many for development and experimental work. It sounds better if it refers to a few stops and starts of a production program. But then we are left with dozens if not a few hundred un-usable engines ( or waiting for new ignition systems?) sitting in storage that were perhaps destroyed in bombing raids?

Perhaps this is all off and they only built a few dozen in in 1939-40-41 and they did spit out 200 222E/F engine in late 1944 and 45 that were perfectly airworthy but never made it to the airframe makers due to bombing. So far we have nothing definitive either way but the seeming inability to get a single 222E/F into the air in any sort of aircraft makes the latter scenario seem unlikely. They sure managed to get enough other semi-experimental engines into the air.