Was the B-29 Superfortress a Failure?

[Shortround6]

The Wright engines had a long and complicated history. The first engines that showed about the same time as the R-2800 were considerably different than the later engines used in the B-29s. For one thing crankcases were several inches shorter. The R-3350 engines were put on hold for a while Wright worked on the R-1820 and the R-2600 engines. AND they spent a crap load of time and engineering time on the R-2160 42 cylinder radial. After that got dropped they went back to the R-3350.

We also have to divorce the R-3350 from the B-29. The B-29 did not cause the R-3350's problems, it might have made a bit worse but it did not cause them. What was fortunate, in a way, was that the demand for the B-29 program caused very few other aircraft to the use the R-3350 engines until it had been fixed.
The C-69 used the R-3350 and had problems, but they only built 20 C-69s and slowly so the problems were not large compared to the B-29s. The C-69s didn't use turbos and were lighter so the engines weren't pushed as hard. They did have problems with overheating.
If they had stopped the B-29 and built the B-32 in much larger numbers at the same time the result would have been much the same. A lot of crashes due to the engines.
And there was no good substitute, The R-3350 was rated at 2200hp max but 2000hp max continuous (like a long climb) while the R-2800 was 2000/2100hp max and 1600/1700hp max continuous (higher numbers are for the C series engines used on the P-47M/N) so you would need 5 or 6 R-2800s and different factories to supply engines.
Or the Allison V-3420. But you either needed a new factory ( start building in 1942) or stop building P-39s, P-63s and P-38s.

 

[Thumpalumpacus]

They NEVER took off with armed nuclear weapons, and the still don't. Modern weapons are automatically armed in a very similar fashion. The pit is removed until the weapon is armed. Either a weapons technician or the bombs arming mechanism inserts the pit and completes tamper and explosive lens shells. The early weapons stored the pits in special containers in the aircraft, rather than inside the bomb.

Right. That doesn't mean that they could not have, which was, after all, my question: could they have done so?

 

[FLYBOYJ]

Right. That doesn't mean that they could not have, which was, after all, my question: could they have done so?

They could have but doing so adds another risk to the mission.

 

[FLYBOYJ]

The wright engines were a failure. A lot of airman died because of this

It was not by far. It had issues in it's early development and many aircraft were lost because of engine fires, but with almost 30,000 built it was far from a failure.

 

[Thumpalumpacus]

They could have but doing so adds another risk to the mission.

That was my impression, but I have no sure knowledge.

 

[SplitRz]

Right. That doesn't mean that they could not have, which was, after all, my question: could they have done so?

Can I add an ancillary question to your? If they COULD have done so, WHY would they have done so?!


Seems like a lot of reasons why you wouldn't. Sitting on a live and ready-to-go 'bucket of sunshine' in an age when a meaningful percentage of overloaded bombers might have a mechanical failure would seem a risk well beyond the lives of just the aircrew...

Maybe you MIGHT want to do it in a more modern setting if you were on a QRA mission close to the front line?

 

[Thumpalumpacus]

Can I add an ancillary question to your? If they COULD have done so, WHY would they have done so?!


Seems like a lot of reasons why you wouldn't. Sitting on a live and ready-to-go 'bucket of sunshine' in an age when a meaningful percentage of overloaded bombers might have a mechanical failure would seem a risk well beyond the lives of just the aircrew...

Maybe you MIGHT want to do it in a more modern setting if you were on a QRA mission close to the front line?

Yeah, I'm not arguing that it would be advisable. I was originally discussing the supposed absolute requirement for in-flight access.

Of course you probably don't want to take off locked and loaded, but entertaining the hypothetical of the Lancaster dropping it, the lack of in-flight bomb-bay access was not necessarily a deal-breaker if it could be armed on the ground. Is that clearer?

 

[SaparotRob]

The bombs were armed in the air so as to avoid accidentally nuking Tinian should the plane crash on take off.

 

[special ed]

All of this back and forth has forced me to go through my stack of books. Fortunately, after only an hour I found "The Tibbets Story" almost where it should have been. Upon rereading portions, I found one thing I had forgotten. Tibbets was one of the first military pilots to test the 29. Planning tactics, he was disappointed with the high altitude performance:

" one thing we learned in this test program was the difficulty of maintaining control of the airplane while flying in the thin air at 30000 feet...it would be almost impossible to fly the B-29 at high altitude in the tight formations we had with the Fortress in raids over Europe....the B-29 assigned to me for these tests was fully equipped...weapons and armor plate...once, when it was down for maintenance I borrowed an aircraft (a school trainer) with tail guns only and no armament... The plane was 7000 pounds lighter, what a difference in performance...it was an unexpected payoff in fighter defense.... between 30 and 35 thousand feet, I could turn inside the P-47 used for attacking us... when he tried to get on our tail, I simply turned inside of him."

The strategy for bomb delivery Tibbets worked out was to get 8 miles from the bomb drop (minimum recommended by scientists) by a sharp diving turn of 155 degrees which would put considerable strain on the airplane. The part I remembered reading best, was an attempt by Gen. LeMay to take the mission for the glory/publicity and have his operations officer fly the plane on the mission. Tibbets took Col. Blanchard on a pumpkin drop mission to Rota riding in the jump seat. After 11 months training all of Tibbets' crews knew their missions depended on exact timing and flying. They arrived at the aiming point at Rota exactly as estimated, dropped exactly on target, began the 155 degree diving turn with full power. Blanchard sat paralised by G forces, his face pale. They returned to Tinian within 15 seconds estimated of the ETA time. LeMay and Blanchard were satisfied and Tibbets did not have to go over LeMay's head to Arnold.

As to arming the bomb in flight, the decision to arm in flight was the thought a crash on takeoff would "wipe out half of the island." Captain "Deak" Parsons USN volunteered to arm it inflight. Parsons had previously sided with Gen. Groves and Oppenheimer against in flight arming.

The book is a good read, the first half is about a young Tibbets and his time in B-17s over Europe and Africa.

 

[SaparotRob]

Of course, my takeaway is the B-17 flew better at high altitude than the B-29.

 

[FLYBOYJ]

All of this back and forth has forced me to go through my stack of books. Fortunately, after only an hour I found "The Tibbets Story" almost where it should have been. Upon rereading portions, I found one thing I had forgotten. Tibbets was one of the first military pilots to test the 29. Planning tactics, he was disappointed with the high altitude performance:

" one thing we learned in this test program was the difficulty of maintaining control of the airplane while flying in the thin air at 30000 feet...it would be almost impossible to fly the B-29 at high altitude in the tight formations we had with the Fortress in raids over Europe....the B-29 assigned to me for these tests was fully equipped...weapons and armor plate...once, when it was down for maintenance I borrowed an aircraft (a school trainer) with tail guns only and no armament... The plane was 7000 pounds lighter, what a difference in performance...it was an unexpected payoff in fighter defense.... between 30 and 35 thousand feet, I could turn inside the P-47 used for attacking us... when he tried to get on our tail, I simply turned inside of him."

The strategy for bomb delivery Tibbets worked out was to get 8 miles from the bomb drop (minimum recommended by scientists) by a sharp diving turn of 155 degrees which would put considerable strain on the airplane. The part I remembered reading best, was an attempt by Gen. LeMay to take the mission for the glory/publicity and have his operations officer fly the plane on the mission. Tibbets took Col. Blanchard on a pumpkin drop mission to Rota riding in the jump seat. After 11 months training all of Tibbets' crews knew their missions depended on exact timing and flying. They arrived at the aiming point at Rota exactly as estimated, dropped exactly on target, began the 155 degree diving turn with full power. Blanchard sat paralised by G forces, his face pale. They returned to Tinian within 15 seconds estimated of the ETA time. LeMay and Blanchard were satisfied and Tibbets did not have to go over LeMay's head to Arnold.

As to arming the bomb in flight, the decision to arm in flight was the thought a crash on takeoff would "wipe out half of the island." Captain "Deak" Parsons USN volunteered to arm it inflight. Parsons had previously sided with Gen. Groves and Oppenheimer against in flight arming.

The book is a good read, the first half is about a young Tibbets and his time in B-17s over Europe and Africa.

Great info - and then you have to look at the Silverplate B-29s. They were lighter and had slightly more powerful engines than the stock B-29s of the day.

 

[special ed]

Could be why FIFI is so maneuverable.

 

[Thumpalumpacus]

The bombs were armed in the air so as to avoid accidentally nuking Tinian should the plane crash on take off.

That's what I've read as well.

 

[wuzak]

The wright engines were a failure. A lot of airman died because of this

It was not by far. It had issues in it's early development and many aircraft were lost because of engine fires, but with almost 30,000 built it was far from a failure.

It could be argued, when looking at early models, that the Merlin was a failure.

 

[GrauGeist]

In regards to my earlier statement about the R-3350's - yes it did take quite a while to mature.
Granted, the first prototype ran in 1937, but due to the demand for the R-2600, development was not a priority.

The R-3350 is not fly until 1941, when it was tested in the B-19.

Even by 1943, with the R-3350's program ramped up, it was still having issues with the rear cylinders overheating and the lack of adequate clearance between the engine and B-29's cowling amplified the problem.

That and the issue of cylinder valve failures needed to be worked out.

But it took time and several changes to get the valve problem fixed as well as the low speed overheating corrected.

This is what I was referring to up-thread.

Perhaps if development of the R-3350 had begun in earnest from the start, these issues *may* have been ironed out by 1943.
Instead, it was a rush from 1941 to 1943 to get the engine set up and ready for the B-29 program.

 

[EAIAnalog]

The first B-29 arrived at Wright Field, Ohio, on December 2 and underwent extensive modification to the bomb bay. To accommodate the length of the gun-type shaped weapon (Little Boy was originally supposed to be approximately 17 ft, but was later reduced to 10 ft), engineers removed the B-29's four bomb bay doors and the fuselage section between the bays and replaced them with a single 33 ft bomb bay. This modification project resulted in the removal of all the rear gun stations. Each plane was designed to carry either type of device; either Little Boy type in the forward bay or Fat Man type in the rear. New bomb suspensions and bracing were also implemented and separate twin-release mechanisms were mounted in each bay. Engineers also placed motion picture cameras in the bays to record the test of the new release mechanism.

As I read through this thread I ran across this, which I realize is a quote from another source. However the highlighted part of this quote makes no sense. The fuselage section between the bomb bays contains the main wing spar and the radar antenna. So I'm not sure what amazing modifications could be made to yield a 33 foot bomb bay. As I remember, Thin Man (the plutonium gun-bomb) was ~17 feet long, and there was an effort to figure out how to modify the forward bomb bay to accommodate its length. But that was abandoned when Little Boy (the uranium gun-bomb) was selected as it was only ~10 feet long (each bomb bay is approximately 12 feet long). Also, the bomb bays had to be modified internally to support a single bomb, since bombs were normally carried in racks on the sides of the bay.

The implication of the quote is that all Silverplate B-29's had a 33 foot bomb bay. But pictures of the Enola Gay show the normal forward and aft bomb bay door configuration. And pictures of her forward bomb bay looking aft show a pristine wing spar.

As an aside, no Little Boy style bomb was tested because the scientists were certain that it would work.

 

[EwenS]

As I read through this thread I ran across this, which I realize is a quote from another source. However the highlighted part of this quote makes no sense. The fuselage section between the bomb bays contains the main wing spar and the radar antenna. So I'm not sure what amazing modifications could be made to yield a 33 foot bomb bay. As I remember, Thin Man (the plutonium gun-bomb) was ~17 feet long, and there was an effort to figure out how to modify the forward bomb bay to accommodate its length. But that was abandoned when Little Boy (the uranium gun-bomb) was selected as it was only ~10 feet long (each bomb bay is approximately 12 feet long). Also, the bomb bays had to be modified internally to support a single bomb, since bombs were normally carried in racks on the sides of the bay.

The implication of the quote is that all Silverplate B-29's had a 33 foot bomb bay. But pictures of the Enola Gay show the normal forward and aft bomb bay door configuration. And pictures of her forward bomb bay looking aft show a pristine wing spar.

As an aside, no Little Boy style bomb was tested because the scientists were certain that it would work.

The description given in the Crowood book on the B-29 is this

"The bomb bay doors were removed from the two bomb bays and the standard bomb racks were removed. The radar radome was removed from the area between the bomb bays and two new, long bomb bay doors were installed, which covered the new single bomb bay. To transport the bomb, two glider tow cable attach-and-release mechanisms were modified and installed in the bomb bay; these connected to the two attachment lugs ofvthe Thin Man bomb."

Elsewhere I've read that some of the bulkheads under the wing spar were also cut away. Thin Man itself was suspended under the wing spar. It also retained the turrets.

These mods were only applied to the very first Silverplate aircraft B-29-5-BW 42-6259 assigned Secret Project Number MX-469 and codename Pullman.

Photos here:- (click on the description and history cross)

Mk1

Specifications DesignerLos Alamos Service1944 (Cancelled)TypeGunDimensions204″ x 23″Weight?Yield? Application PrototypeThin-Man Description & History Man’ weapon being develop…

nukecompendium.com

The other Silverplate conversions retained the separate bomb bays.

Later similar , but not identical, mods were made to B-29 converted to carry Grand Slam and T-12 Cloudmaker bombs.

 

[FLYBOYJ]

As I read through this thread I ran across this, which I realize is a quote from another source. However the highlighted part of this quote makes no sense. The fuselage section between the bomb bays contains the main wing spar and the radar antenna. So I'm not sure what amazing modifications could be made to yield a 33 foot bomb bay. As I remember, Thin Man (the plutonium gun-bomb) was ~17 feet long, and there was an effort to figure out how to modify the forward bomb bay to accommodate its length. But that was abandoned when Little Boy (the uranium gun-bomb) was selected as it was only ~10 feet long (each bomb bay is approximately 12 feet long). Also, the bomb bays had to be modified internally to support a single bomb, since bombs were normally carried in racks on the sides of the bay.

The implication of the quote is that all Silverplate B-29's had a 33 foot bomb bay. But pictures of the Enola Gay show the normal forward and aft bomb bay door configuration. And pictures of her forward bomb bay looking aft show a pristine wing spar.

As an aside, no Little Boy style bomb was tested because the scientists were certain that it would work.

From what I understand the modification I referenced was done outside of the factory (Wright Patterson) and it was the aircraft tested at Muroc, basically the Silverplate prototype. I don't know what was done to address the main spar but a major bulkhead was moved or cut to accommodate this so the modification was huge and time consuming.

My apologies if I gave the implication that this was done on all Silverplate B-29s

EDIT see post 137

 

[EwenS]

B-29-5-BW 42-6259 was damaged in a landing accident in Dec 1944; transferred to storage at Davis-Monthan AAF; then assigned to Fort Worth AAF, Texas for use as an instructional aircraft. It was scrapped in May 1948.

The last 7 Silverplates also came from the Boeing Wichita factory. All the others came from the Martin Omaha factory.

 

[EAIAnalog]

EwenS, thanks for the link. I hadn't seen any pictures of a B-29 modified to have those 33 foot bomb doors. To see what has been removed, check out the 3D walkthrough of the B-29 at the Museum of Flight. You can find it here. You can move from circle to circle, and do a 360 at each stop. The circles are where the camera was placed to take a bunch of pictures that were then stitched together to make the overall image.

If the S/N of the test aircraft is 42-6259, I think it was pulled from current inventory to do the modification testing. What I've read says the Enola Gay was the first Silverplate aircraft, and its S/N was 44-86292. According to Wikipedia, Col. Tibbets personally selected the aircraft on May 9, 1945, while it was still on the assembly line. The history write-up on the link says that the Thin Man design was abandoned on July 17, 1944. So that would mean the modification centers would not have to make any of the modifications required for the 33 foot bomb bay.