4-engined bomber for 1943-44

[tomo pauk]

Hello,
This time, you run the design phase of the next-gen heavy bomber. The plane should be in production by Jan 1943, and it must be able to receive the upgrades, in order to stay competitive in 1944. The gun armament (if fitted*), engines electronics are the ones historically available (= production being in good numbers) for the air force of your choosing, the plane featuring 4 engines. The thread acknowledges that production priorities were shifting in some belligerent nations, but that has no influence on the thread - your bomber need to be as good as possible within the time frame. The design should start from a clean sheet of paper, thank you

*you can design both armed non-armed planes, both for day night duties

 

[Shortround6]

Design work can start no later than 1941, and more likely in either late 1939 or early 1940.

"in December 1939, the Air Corps issued a formal specification for a so called "superbomber", capable of delivering 20,000 lbs of bombs to a target 2,667 mi (4,290 km) away and capable of flying at a speed of 400 mph (640 km/h), they formed a starting point for Boeing's response"

"Boeing submitted its Model 345 on 11 May 1940,[5] in competition with designs from Consolidated Aircraft (the Model 33, later to become the B-32),[6] Lockheed (the Lockheed XB-30),[7] and Douglas (the Douglas XB-31).[8] Douglas and Lockheed soon abandoned work on their projects, but Boeing received an order for two flying prototypes, given the designation XB-29, and an airframe for static testing on 24 August 1940,"

"First flight 21 September 1942" first operations "The first B-29 combat mission was flown on 5 June 1944"

Even leaving out the remote gun turrets, the turbo chargers and the pressure cabin and a few other problem areas getting a 4 engine bomber into service is going to take close to 3 years at best. Your crystal ball had better be pretty good.

 

[Vincenzo]

maybe no later than 1940 is best

 

[tomo pauk]

I was thinking more of 1940, for the start of putting the ideas on paper

 

[wuzak]

I'm thinking of something along these lines:

http://i.pbase.com/o4/30/511730/1/64601170.GoVGFvIY.webConvair.jpg

I think the aerodynamics would have been possible in the development phase. The big problem is the engines. Possibly the most powerful/reliable engines in production at the time would be the R-2800. Not sure if they are enough to power such a large aircraft.

The only aspect I wouldn't think could be applied is the nacelles. They were developed from experience which wasn't available in the period when the design needs to be commenced.

Merlins aren't strong enough. Maybe Griffons - 2 stage ones for better high altitude work, maybe turbocharged (I know not historically done). Alternative engines I would push for altitude versions of the Sabre, possibly turbocharged, and would encourage Allison to develop the V-3420. So you have 3 possibilities there, in case one or more fails.

I would drop the pointed nose, and opt for a more traditional flight deck. I would tend to keep the aircraft unarmed, or just limit the armament to a rear firing 20mm cannon, controlled remotely.

 

[tomo pauk]

Great plane, the Rainbow
The plane should be of scale that fits for R-2800, with the nacelles looking like those of B-26. Turbo seem like a mandatory choice.

 

[wuzak]

Like these?

http://discoverfrance.net/France/Images/Transportation/Air/Martin_B-26_Marauder-01-lg.jpg

 

[tomo pauk]

Hmm, maybe we can steal from F4U, regarding the cowling

 

[wuzak]

Hmm, maybe we can steal from F4U, regarding the cowling

Still nowhere near as good as the Rainbow's. Also, we are probably yet to see the tight Fw190 cowlings.

We have, however, seen evidnece of the performance of leading edge radiators (from research conducted by Westland for the Whirlwind), and the Rainbow has leading edge intakes between the naclles to feed oil coolers, intercoolers and engine air.

 

[tomo pauk]

My take is that the F4U's cowling is the best we can get for the US bomber for 1943 - not bad IMO.
The B-17 was also featuring the leading edge intakes, feeding the compressors inter coolers buried in the wings.

 

[Shortround6]

Leading edge intakes may date back the the Hughes racer of 1935. The trick is not putting the intake in the wing, it is routing the intake to the carburetor, or actual engine inlet, without loosing much of the pressure gained from the RAM effect. Proper sizing and gradual bends in the ducts are important.

 

[davparlr]

I have already stated my position on what I considered the missing bomber generation.

This is what I would do with hindsight. In 1939/40 I would cancel the B-26 and increase production of the B-25. I would increase production of the R-2800/R-2600 (possibly cancelling the B-17 or B-24 freeing engine production facilities?). Modify the B-26 contact to a four engine configuration, basically stretching the fuselage and increasing structural strength. Specifications:
Cruise speed-315 mph
max cruise (combat cruise)-330 mph
max speed-350 mph
range-2000 miles with 10,000 lbs of bombs
combat ceiling-30,000 ft.
Max gross weight-reccomended 90,000 lbs
While I would not specify engine type, R-2800 with a P-47 type turbo would seem the obvious choice. Possibly R-2600 with similar turbo.
Armament-need to ponder
Pressurization-none required
Teach bomber pilots to get their head out of low speed, low wing loading flying and become modern pilots.

 

[davebender]

He-177A3.
Entered production November 1942. Slightly improved He-177A5 enters production during December 1943. All sorts of room for development of He-177B, He-277 etc. if you want to spend the money.

 

[tomo pauk]

For Germans I'd like to see something powered with DB-603, meybe even with BMW-801D - that would make it a good performer even for Eastern front.

 

[davebender]

If we get the RAF Bomber Command or USAAF budget then why piddle around? Heinkel proposed the He-177B during 1938. The 2,500 hp version of the Jumo 222 engine passed it's 100 hour test during December 1942.

During 1943 we could have a He-177B powered by four 2,500 hp engines.

 

[tomo pauk]

How good/bad was Jumo 222 in 1943 (the engine deserves it's own thread, I mean it)?

As for US engine layout (for R-2800) perhaps the Northrop has the best solution for our time frame:

 

[Vincenzo]

Specifications:
Cruise speed-315 mph
max cruise (combat cruise)-330 mph
max speed-350 mph
range-2000 miles with 10,000 lbs of bombs
combat ceiling-30,000 ft.
Max gross weight-reccomended 90,000 lbs
While I would not specify engine type, R-2800 with a P-47 type turbo would seem the obvious choice. Possibly R-2600 with similar turbo.
Armament-need to ponder
Pressurization-none required
Teach bomber pilots to get their head out of low speed, low wing loading flying and become modern pilots.

i think this specifications are too hard for get in production in january '43

 

[davparlr]

i think this specifications are too hard for get in production in january '43

Why? The B-26 went from contract go-ahead to first delivery in two years, January, 1939 to February, 1941. Just add a year or two for a bigger and better plane and no great technology challenge over the B-26, I just don't see the problem.

 

[tomo pauk]

Maybe a comparison Lancaster/R-2800-bomber/B-29 might come in handy?

 

[wuzak]

Why? The B-26 went from contract go-ahead to first delivery in two years, January, 1939 to February, 1941. Just add a year or two for a bigger and better plane and no great technology challenge over the B-26, I just don't see the problem.

I agree, the performance specifications are similar to the B-29, but with 25% less loaded weight.