Earliest possible introduction of B-29 bomber?

. Same engine problems as bedeviled the B-29 bedeviled the Dominator. It could not carry Fat Man though it could carry Little Boy. It just would have not survived the drop. It would never have replaced the B-17, either. It was not even as good as a B-17 mechanically.

B-17 couldn't match any of these stats

Maximum speed: 357 mph (310 knots) at 30,000 ft

Cruise speed: 290 mph (252 knots)

Range: 3,800 mi (3,304 nmi)

Service ceiling: 30,700 ft

Rate of climb: 1,050 ft/min

Bombs: 20,000 lb

B-32 had twin bomb bays of the same dimension as the B-29. I have no doubt that a Silverplate B-32 would have done just as well

And info from a Pilot I knew who flew B-32 and later B-29s postwar, B-32s had fewer engine problems, the nacelle and cooling flap setups were superior, they ran cooler on ground taxiing and in air in cruise. Mechanically, he found them far superior to the B-24, the B-24s that had replaced B-17s in thePacific over range issues.

Given how Lemay used the B-29s at the end of the war, low level with only tail guns, B-32s could have done fine withou the pressurization and remote control guns.
The Colonel I knew said the B-32 flew better( as in more a pilot's ease in handling) than the B-29 in staying in formation, and far better at landing
 
To be fair If I remember correctly the B-32 was something of a backup to the B-29 if for whatever reason the B-29 was not a success. I suspect their wasn't any drive to fix any faults of the B-32 because of the B-29 being able to enter service as planned.

B-32s never got a 'Battle of Kansas' with AA priority to fix outstanding issues
 
I can only go by USAAF assessments. Some of the things suggested about cowlings are not relevant if the R-3350s blow oil and the engines seize up. Fly at 30,000 feet? Only if the crew is wearing heated sheepskins. The plane's self defense system did not work.

B-17s did work. They were being shifted from Europe to supplement the B-29s for Downfall.

The shackling for bombs was different for the Dominator. It could not carry Fat Man. And as noted, it would never survive a drop.
 

SsgtC

Banned
What if, instead of 4 superduper new engines, as OTL, they go with 6 existing ones? Could that be made to work for an earlier introduction?

Not without designing an entirely new wing to support the extra weight of the engines. Which means you're basically designing an entirely new aircraft. Especially considering the penalty in fuel burn having two additional engines imposes on you. You either accept the reduced range, or find a way to squeeze in more fuel. Likely at the expense of bomb load.
 
Not without designing an entirely new wing to support the extra weight of the engines. Which means you're basically designing an entirely new aircraft. Especially considering the penalty in fuel burn having two additional engines imposes on you. You either accept the reduced range, or find a way to squeeze in more fuel. Likely at the expense of bomb load.
Well, but if we're looking at a PoD early enough, the AAC might say 'wow, the planned engines are awfully risky, let's go with something we KNOW we can do'.

And as for fuel consumption, surely that scales more closely with horsepower than with number of engines. If 6 of engine A have about the same horsepower as 4 of engine B, won't the fuel consumption be about the same? Especially if you can shut down a pair during cruise (which would be easier and less risky with 6 total than with 4).
 

SsgtC

Banned
And as for fuel consumption, surely that scales more closely with horsepower than with number of engines. If 6 of engine A have about the same horsepower as 4 of engine B, won't the fuel consumption be about the same? Especially if you can shut down a pair during cruise (which would be easier and less risky with 6 total than with 4).

Not even close. I'm going to use a modern example since I'm more familiar with the numbers, but the principle still holds true. The Boeing 777-300ER Burns about 8,100kg of fuel per hour and develops about 230,000 pounds of thrust. Contrast that with the Boeing 747-400. The 747 has four engines verses the 777's two engines. The 747 burns about 11,100kg of fuel per hour and develops 236,000 pounds of thrust. It is always more efficient to develop the same power with a single engine than with multiple engines.
 
Dathi is entirely correct. Horsepower specific fuel consumption, F sub e, is entirely dependent on horsepower output, and in no way related to the number of engines delivering it. Further, the B-32 cowl, and particularly the exit flap arrangement generated significantly less aerodynamic drag when open beyond about 25%. B-29 rate of climb at the start of a typical Pacific mission was substantially reduced by the drag of the cowl flap opening required to attempt to cool the early CW R-3350
engines. In the B-29 it was a choice between excessive cylinder head temperatures or inadequate rate of climb. Also a problem with the B-32, but to a considerably lesser extent. An earlier post mentioned the '3350's tendency to dump oil... This was usually the result of a piston burn thru at full power with inadequate cooling.

For an example of advanced engine nacelle design look at the Republic XF-12: fan cooling and a translating ring exit which did not increase drag when open.

As for the six engine possibility- same wings with no changes, bolted to a new center section with existing engine nacelles and landing gear. Little new structure to design and, considering airfoil's relatively small pitching moment, the existing horizontal stabilizer might prove adequate. No need for the 3350s at all.

Dynasoar
 
Further, the B-32 cowl, and particularly the exit flap arrangement generated significantly less aerodynamic drag when open beyond about 25%

I had notes saying that on approach with those flaps wide open, would give enough drag to act as an extra set of airbrakes if landing hot
 
And as for fuel consumption, surely that scales more closely with horsepower than with number of engines. If 6 of engine A have about the same horsepower as 4 of engine B, won't the fuel consumption be about the same? Especially if you can shut down a pair during cruise (which would be easier and less risky with 6 total than with 4).

I've really only heard of B-36s idling the props for mechanical issues, but could restart the turbines at will.

R-3350 power to weight ratio was .82hp/lbs
R-2800 power to weight ratio was .89hp/lbs

So the R-2800 looks good on a per pound basis, but those ratios don't include the mounts, nacelle and ducting weight, so the fewer the engines you have, the overall weight is less.

But now say you had 3500 HP from 3900 pounds of Wasp Major at 1.11hp/lbs

Now too much HP on a shaft means large diameter props and/or more blades, so even had Lycoming got that massive 6000 pound, 5000HP XR-7755 running, it would have needed a huge airframe for prop clearance

Putting Wasp Majors on the B-29 wing, you had to raise them up slightly, prop diameter was over 17'
640px-WB-50D.JPG
 
The plane had more technical glitches than the B-29, including a pressurization system that was unfixable. The same goes for the remote weapon stations. Same engine problems as bedeviled the B-29 bedeviled the Dominator. It could not carry Fat Man though it could carry Little Boy. It just would have not survived the drop. It would never have replaced the B-17, either. It was not even as good as a B-17 mechanically. As a matter of fact, the plane was abandoned, when the B-29 for all of its faults proved that it could operate halfway decently out of China. The B-32 was a piece of junk.

Once again, given the R-3350 problems, how was the B-29 going to be ready before May 1944?
We're talking all things going accordingly to the original time table, reality has a way of messing up the best plans.
The B-32 had some advantages over the B-29 except for the critical ones of range and altitude.
 

Archibald

Banned
This thread has many interesting ideas. I'm really tempted by the concept of a 4*R-2800 "mini B-29" or a 6*R-2800 "intermediate bomber" something between B-29 and B-36. Surely, the R-2800 isn't a magic / silver bullet, but there are interesting possibilities there.

There were 5 major categories of heavy bombers in the 40's.
B-17 & B-24 (less powerful engines, no pressurisation)
B-32 (R-3350, no pressurisation)
B-29 (R-3350, pressurisation)
B-50 (R-4360) *4
B-36 (R-4360) *6
It might be interesting to create "intermediate classes" with R-2800s. Perhaps by screwing up some P-47s to free their engines (P-38 can handle the escort job before the P-51 steps in).
 
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If the USAAF had been willing to trade bomb load for fuel, there is a possible answer in the XB-33 Super Marauder. it still would have been a bit short legged,
 
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If the USAAF had been willing to trade bomb load for fuel, there is a possible answer in the XB-33 Super Marauder. it still would have been a bit short legged,

Of all the possibles past the B-29 and B-32, was also the bomber version of the Constellation C-69 transport, the XB-30
lockheed-xb30-heavy-bomber-prototype-united-states.jpg

Bomber version never left paper, but was estimated to be slightly faster, but only 16,000 pound bombload to the desired 5000 mile range
 
Of all the possibles past the B-29 and B-32, was also the bomber version of the Constellation C-69 transport, the XB-30
lockheed-xb30-heavy-bomber-prototype-united-states.jpg

Bomber version never left paper, but was estimated to be slightly faster, but only 16,000 pound bombload to the desired 5000 mile range

If Kelly Johnson was not involved, I would not trust Lockheed then or now to design toilet paper.
 
If Kelly Johnson was not involved, I would not trust Lockheed then or now to design toilet paper.
Postwar, the Lockheed Constellation was far more successful than the Boeing Stratocruiser (B-50 with passenger area) for moving people cross country reliably, and that was with the Connies having TurboCompound R-3350s with PRTs that blew regularly
 
Again, lots of good posts. Marathag's photo of a B-50, which was basically a B-29 fitted with much more powerful and reliable Pratt and Whitney R-4360 and stronger 7075-T6 alloy aluminum structure, reminds me of the Boeing XB-54. This project, which wound up before I got to Wright Field (WPAFB), in several of its paper incarnations, was a stretched B-50 with the six engine configuration I've occasionally suggested here. Even lugging huge drop tanks, the '54 would substantially outperform the earlier versions of the B-36.

More on the B-32 later.

Dynasoar
 
One issue with the Constellation was that, for aerodynamic efficiency,it had an area ruled fuselage. This was unlike most large aircraft of the time which basically had cylindrical "tube" fuselages for most of their length. This latter sort of design allowed for expansion simply by inserting a plug or putting in a bulge. With an area ruled fuselage you need to redo the entire design to enlarge the fuselage.
 
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