Luftwaffe XP-75?????

GrauGeist said:

F82 (twin Mustang):
Empty weight: 15,997lbs (7,271kg)
Max speed: 460Mph (740Kmh)

Bf109Z (based on joined Bf109F):
Empty weight: 13,224lbs (6,000kg)
Max speed: 462Mph (743Kmh)

Me609 (based on joined Me309):
Empty weight: 11,660lbs (5,247kg)
Max speed: 472Mph (760Kmh)

Compared to Me262A1/a (original configuration with Jumo004 X 2):
Empty weight: 9,709lb (4,404kg)
Max speed: 559Mph (900Kmh)

Now, we remove the two Jumo 004B engines: 1,585lb (719kg) x 2 = 3,170lb (1,438kg)
Me262A1/a without engines = 6,539lbs (2,966kg)

So let's take 2 DB603 V-12 engines, and install them into the empty Me262:
DB603 @ 2,030lbs (920kg) X 2 = 4,060lbs (1,840kg)
Result is a weight of 10,599lbs (4,806kg)

That's a weight increase of 890lbs (402kg) with a reduction of roughly 100Mph (160Kph) in speed...

And what happens if you put ammunition and fuel in the machine?

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With 12000lb (when we add gearing, prop,etc for prop 262) vs. 16000lb (F-82) and 500HP more, plus the swept wings, why do you think that the speed would've been the same?
As for ammo and fuel, methinks that other planes would need the same stuff too...

GrauGeist said:

As far as "Boom and Zoom" tactics go, it works as long as the enemy can't keep up with you...The allies had aircraft that could both "Boom and Zoom" and "Turn and Burn"...

The Germans dropped the Doppelganger projects in favor of the Ta152, because it of thier development problems and the fact that they just weren't performing as well as they had hoped.

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The Zwilling (with hindsight*) could be made back in 1941 with 109F airframes, making the Ta-152 not a competitor.

*Since the thread is o 'what-if' type, hindsight is 100% OK.

Colin1 said:

I don't think it adds up to 500mph
saddled with props, it won't be alot cleaner than a P-82 airframe, if at all, given that it now has three nacelle frontal cross-sectional areas to the P-82's two.

I'd be surprised if it was faster than a P-82 or de Havilland Hornet and that was some margin away from 500mph too.

It sounds like you'd be running at the bomber streams in a jet wannabee that can't run as fast as a jet and can't dogfight that well once it's caught.

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As for the numbers (stats), see my previous posts.

As for not being to go fast as the jet, I've never promised that But I did promise deploymenta a full year earlier then the ordinary 262.
And I can't see what would've caught it in 1943, even with the max speed being 750 km/h, let alone 800km/h I'm pushing for.

Why go to all that trouble when the Heinkel He280 was already available?

I know it had jet engines, but it was ready for production by 1943 and it's performance was superior to the Me262 in many respects. And it was very capable in a dogfight, having out performed a Fw190 in a mock dogfight during trials.

As a matter of fact, I always thought the He280 would have been the perfect escort for the Me262 in an interceptor role.

He280 specs:
Empty weight: 7,073lb (3,215kg)
Max speed: 512Mph (820Kmh)
Service ceiling: 32,000ft (10,000m)
Armament: 20mm MG 151/20 cannons X 3

Seeing as how light it is, I suppose you could replace the two HeS.8 jet engines with piston engines and still come out ahead. 8)

tomo pauk said:

With 12000lb (when we add gearing, prop,etc for prop 262) vs. 16000lb (F-82) and 500HP more, plus the swept wings, why do you think that the speed would've been the same?
As for ammo and fuel, methinks that other planes would need the same stuff too...

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I think the swept wing is incidental here
it does not in itself imbue the a/c with more speed, it will afford more speed to a suitably engined a/c that can take advantage of it; I can't think of many (if any) piston engines that could.
I think it would be the same (or thereabouts) for the reasons I outlined, you have three cross-sectional areas with the Me262 plus propeller arcs for two plus propeller arcs with the P-82. You have made no mention of how your bird will overcome, for example, cooling losses while we know how well the P-82 achieves this; the Spitfire IX needed 200hp more than the P-51 to fly at the same 400mph so you can see that your 500hp differential is already being whittled away.
If it IS faster I doubt it will be decisive and I still don't see any reason why it would achieve 500mph.

Well, with fuel and ammo factored in, the P-82 was good for 462mph, we know that. The same has not been factored in for your a/c in terms of all-up weight and of course, it must be - without fuel it's not going anywhere, without ammo it's not going to be alot of use once it does.

Instead of all this "what-if" projects I would rather go with the real thing - Dornier Do 335 Pfeil. Here you have aircraft with great development potential, capable of performing tasks of heavy day and night fighter and fighter-bomber and a design which, if fully developed might become fastest piston engined fighter ever build.

Do 335A-1 specs:
Powerplant: two 1750hp DB 603A-2
Weights: empty 16314lb (7400kg), maximum take-off 21164lb (9600kg)
Max Speed: 478mph (770km/h)
Service ceiling: 37400ft (11400m)
Armament: one 30mm MK 103 and 2xMG 151 15mm cannon + 500kg of bombs internally and 2x250kg bombs externally

It would have been interesting to see how it would performed with swept wings though.

imalko said:

It would have been interesting to see how it would performed with swept wings though.

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I agree totally with your what-if notion
the Do335 is a much better proposition, it has two DB603s but in the same frontal cross-sectional profile as a conventional single-engined fighter and was very clean aerodynamically. 478mph is very impressive, the Do335 was not a small bird but it's still not 500mph.
The wing of the Do335 did have a 13 degree sweep at the leading edge and 6 degrees at the trailing edge. If Dornier's engineers thought that the powerplants potential warranted a greater taper, why do you think they would not have implemented it?

One can only speculate.

Here is quote from The Concise Guide to Axis Aircraft of WW2 by David Mondey:

"Designed by Ulrich Hutter and built by Scempp-Hirth in 1939, the unconventional tandem engine layout patented by Dr Claudius Dornier in 1937 was adopted by RLM for a bomber under the project number Do P.231, despite the fact that Dornier's original design proposal was for a fighter! When work was at an advanced stage the project was canceled(!), but an emerging need for a high-performance fighter resulted in the reactivation of Dornier's plans for interceptor."

So, they developed tandem engine layout back in 1939 and then cancelled the project even if it showed great promise for high performace! I think this is just another example of nazi's inabillity to reckognize the potential of particular aircraft. And what was this opsession with bombers, same as with Me 262.

My feeling is that same was the case when swept wings are concerned. On the other hand, at the time swept wing concept was still something new (Do 335 made its maiden flight in september 1943) and even most of the first jet aircrafts (both German and Allied) were designed with straight wings (Me 262 and Me 163 excluded).

Or perhaps they didn't have time for further development. Remember that Do 335 was build in small numbers (37 in total including prototypes) but in great number of versions: A-0 and A-1 fighters and fighter-bombers, A-4 reconnaisance aircraft, A-10 and A-12 two seat trainers. Then there were B-1 to B-4 heavy fighters and B-5 to B-8 night fighters. Basically it was all one big mess.

But there was one example - Do335B-4 - which was fitted with a wing of higher aspect ratio, but I have found no further information about this aircraft.

Hi GrauGeist

Yes, the He-280 was a nice plane, yet I went for 262 as a basis because of swept wings.

My comments in bold.

Colin1 said:

I think the swept wing is incidental here
it does not in itself imbue the a/c with more speed, ...
?? It suerly does!
...it will afford more speed to a suitably engined a/c that can take advantage of it; I can't think of many (if any) piston engines that could.
I think it would be the same (or thereabouts) for the reasons I outlined, you have three cross-sectional areas with the Me262 plus propeller arcs for two plus propeller arcs with the P-82. You have made no mention of how your bird will overcome, for example, cooling losses (please elighten me why would my bird have cooling loses?) while we know how well the P-82 achieves this (I don't know, lplease explain); the Spitfire IX needed 200hp more than the P-51 to fly at the same 400mph so you can see that your 500hp differential is already being whittled away.
262 was as better as P-82 as P-51 was better then Spitfire when it comes down to aerodynamics.
If it IS faster I doubt it will be decisive and I still don't see any reason why it would achieve 500mph.

Okay, then would you agree that a 4x30mm could fly 480mph in 1943?

Well, with fuel and ammo factored in, the P-82 was good for 462mph, we know that. The same has not been factored in for your a/c in terms of all-up weight and of course, it must be - without fuel it's not going anywhere, without ammo it's not going to be alot of use once it does.

Since the prop 262 would be lighter, smaler, more powerfull, with swept wigs, I don't see any reason that it wouldnt outperform the F-82.

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Swept wings don't increase speed just by themselves. They increase speed in the transonic range, which is greater than the speed these aircraft can realistically attain in level flight. Otherwise, swept wings add weight, so lift and drag increase and speed would decrease.

Adopting piston engines for the Me 262 would increase weight a fair amount, especially with the larger nacelles. The wing is pretty small and wing loading is already high on the normal Me 262.

I'm not a great fan of the Ar 240. Its a nice plane but most of the performance comes from having a small wing and limited high altitude performance. A large fighter built around the Jumo 222 or DB610 might be interesting...

imalko said:

One can only speculate.

My feeling is that same was the case when swept wings are concerned. On the other hand, at the time swept wing concept was still something new (Do 335 made its maiden flight in september 1943) and even most of the first jet aircrafts (both German and Allied) were designed with straight wings (Me 262 and Me 163 excluded).

Or perhaps they didn't have time for further development

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Willi Messerschmitt
was working on turbo-jet feasibility in 1938. By 1941 he knew all about swept-wing design, his aerodynamicists having shown him a wind-tunnel model with a sweep of 18 degrees and then another of 35 degrees, both raising incrementally the limiting Mach number. By this time, the Me262 airframe was pretty much worked out.

The delay was for engines that could take advantage of such a radical design.

Granted that Willy Messerschmitt knew allot about swept wing design by 1941, but could he persuade top officials of the RLM of its advantages.It appears that they were quite conservative about this question.

I have read in a book "FIGHTER-The True Story of the Battle of Britain" by Len Deighton, that in 1941 RLM decided that all new weapon development programs (including new jet aircrafts) is to be discontinued if they can not offer results important for the war effort within period of 6 monts. This was another reason (coupled with problems with engines) for delays in development programe of Me 262. Even Galland himself said that becouse of inabillity of RLM to reckognize importance of Me 262 this aircraft entered operational service 2 years later then it would otherwise been the case.
Only when it was too late the programes such as Me 262 were given priority, and even then Hitler insisted that Me 262 should be developed as a bomber.

As for Do 335, my guess is that either they didn't have time for further tests and development by incorporating further swept wings in its design (as you have pointed out Do 335s wings were slightly swept already), or, perhaps, they did conducted some tests with swept wings on Do 335 and decided that increase in performace was not so significant to justify that course of development.

imalko said:

But there was one example - Do335B-4 - which was fitted with a wing of higher aspect ratio, but I have found no further information about this aircraft.

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No existing photos that I can find

Do335B-4: Destroyer, fitted with the enlarged 45.5m^2 wing and DB603L engines. A further development was proposed with a pressurized cockpit but this was abandoned. Work to have been carried out at DWM (Dornier-Werke, Munchen-Oberpfaffenhofen).

The proposed Do335 production was reduced to 3,135 aircraft by Industrie Lieferplan 227 (see attachment) which was issued on 15Dec44. This called for Dornier in Friedrichshafen to build 5 more A-0s (in addition to the 5 already completed) plus 20 A-10 trainers. Dornier in Munchen were to build 50 A-1s (of which 1 had already been converted) 560 B-2s and 400 B-4s, converting 30 A-1s to A-6s. Heinkel in Oranienburg were to build 420 B-6s and 470 B-8s.
The Luther company were to build 200 B-6s and 325 B-8s and convert 195 aircraft A-12 trainers.
Finally, another 230 A-1s and 160 A-6s were to be built by a company as yet undecided.

Hi Colin!

Thanks or additional info about Do 335B-4 and those planned production figures for Do 335 series.
I'm curious is that taken from some book or....?

Cheers!

I have read in a book "FIGHTER-The True Story of the Battle of Britain" by Len Deighton, that in 1941 RLM decided that all new weapon development programs (including new jet aircrafts) is to be discontinued if they can not offer results important for the war effort within period of 6 monts.

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I own several of Mr. Deighton's books including that one. Some of his statements aren't exactly correct...

imalko said:

I'm curious is that taken from some book or....?

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Source

Dornier Do335 Pfeil The Luftwaffe's Fastest Piston-Engine Fighter
J Richard Smith and Eddie J Creek with Gerhard Roletschek
Classic Series
ISBN: 1 903223 67 9

Ian Allan Publishing

Thanks again Colin, I appreciate it.

red admiral said:

I'm not a great fan of the Ar 240. Its a nice plane but most of the performance comes from having a small wing and limited high altitude performance. A large fighter built around the Jumo 222 or DB610 might be interesting...

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Hi Red Admiral,

I agree that larger engines are most important for higher performance. And with the cancelation of jet engines, we likely would see those engines entering service instead.
However, let me explain why I do prefer the Ar-240. Ok, it´s neither as beautiful nor as efficient aerodynamically, esspeccially compared to the Fw-187, which also benefits from beeing a matured design sooner.
Historically, the Ar-240 could have entered mass production in 1942 but by this time the first two Arado´s Ar-234 jet bomber prototypes were already finished and waited for delivery of their powerplants. Accepting the Ar-240 would have either stalled or heavily delayed the Ar-234 program as the company lacked the ressources to push both designs. The historical choice to abandon the Ar-240 in favour of the more promising jet bomber/recon was understandable and justified from the companies perspective.
In our scenario, however, we must expect that no jet engines would become aviable, hence the Ar-234 would find itselve at very low probability. The company therefore would have every reason to push the Ar-240 into serial production in order to avoid becoming once more a license contractor for Junkers or Focke-Wulf.
This gives us the opportunity to discuss the performance of the Ar-240, esspeccially with those of the twin engined Fw-187. The latter was handicapped by comparably low performance 610hp Jumo-210 engines (=445 kg dry each) but one prototype (Fw-187 V7) was equipped with 30% heavier 960 hp Db-600A engines instead and recorded a stellar 630 km/h top speed. To put this into context, the 1150hp Db-601A/B driven Ar-240AV prototypes were good for only 615 to 620 km/h at optimum altitudes, albeit they achieved this speed with full armement and unlike the Fw-187, they had no spooky wing surface evaporation cooling but more reliable ducted spinner radiators instead.
In other words, the Ar-240 AV-prototypes achieved 615 km/h at operational condition while the Fw-187 V7 exceeded the Ar-240´s speed only by use of unservicable radiator designs and without turreted defense armements, military equipments or pressurized cockpits.
Unlike the Fw-187, I also see the Ar-240 beeing able to accept larger powerplants more easily, too. In fact it had no problems shifting from Db-601 to the rather large Db-603 (attributable to the fact that the Db-601 was only a stop gap engine, the Ar-240´s engine nacelles had a sufficiant layout designed for large engines like the Jumo-213 and Db-603 to begin with).
Experiences from the Ju-288 program showed that the dimensions of the Jumo-213/db-603 and Jumo-222 engine nacelles are not significantly different in the typical Jumo-standart cowling with radial frontal radiator. The Jumo-222A is 16% heavier than the Jumo-213A and thus I don´t see impossible obstacles for a refit, altough it must be stressed that this is speculative. Even the BMW-801 was tried on the Ar-240! The Ar-240 -unlike the Fw-187- should therefore be able to cope with the increased weights of the Jumo-222 if such an engine is considered. This should give the Ar-240 a very dramatic performance boost over any contemporaneous piston engined plane.
Finally, it is true that the Ar-240 has a small wingarea and correspondingly a high wingload, esspeccially when compared to other period designs. But I don´t rate this as negative as long as the wing produces more lift in start landing conditions -where necessary.
In fact the wing design layout of the Ar-240 is very sophisticated for the period in question with automatic full span leading edge slats full span trailing edge slotted fowler flaps (compare picture below from a wingdetail of the Ar-240 V1 prototype). This transforms the small wing of the Ar-240 into a very potent lift enhancer with effective lift coefficients exceeding 2.8! This is also confirmed by the lower landing speed of the Ar-240. Despite the very high wingloading of in between 330 and 380 kg/m^2 (depending on version) the Ar-240 had a landing speed of 140 to 160 km/h, right in between bf-109 and Fw-190.
best regards,
delc

davebender said:

I own several of Mr. Deighton's books including that one. Some of his statements aren't exactly correct...

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I can't be judge of that, but I do find his style of writing refreshing and interesting. There is only two of Mr. Deighton's book translated to Serbian - Fighter and Blitzkrieg. You have mentioned there is several others. Can you write titles of those books. I'm curious.

I own these:
Fighter
Blitzkrieg
Blood, Tears and Folly

He also wrote 2 books on French cooking and about a dozen works of fiction.