Americans didn't drop the bomb...
Discussion
According to the National Air & Space Museum, the change to Curtiss electrically controlled pitch propellers was to enable reverse pitch to be used, which, in turn allowed the 'Silverplate' aircraft to land with the bomb on board if necessary. 75 Years Ago: The Flight of the Enola Gay I was guessing that the reason may have been to reduce hydraulic oil use, improve reliability and increase airflow to cool the engine if the electric system had a smaller propeller hub...
One factor that has not been discussed in terms of the altitudes B-29s was intended to fly, is fuel evaporation. At high altitudes, fuel loss through evaporation (boiling) could exceed 2% of the total fuel load (bear in mind this was AvGas (petrol) not AvTur (Kerosene). Keeping the fuel cool when on the ground would reduce the evaporation rate when at altitude, as the fuel would retain the heat it acquired at ground level (maybe another reason that Tiger Force aircraft were painted white)?
This is an interesting read on the problems of the R-3350. The crews reckoned they were more likely to be killed by Curtiss-Wright, the engine manufacturer, than by the Japanese!
The B-29s Achilles heel, the R-3350
One factor that has not been discussed in terms of the altitudes B-29s was intended to fly, is fuel evaporation. At high altitudes, fuel loss through evaporation (boiling) could exceed 2% of the total fuel load (bear in mind this was AvGas (petrol) not AvTur (Kerosene). Keeping the fuel cool when on the ground would reduce the evaporation rate when at altitude, as the fuel would retain the heat it acquired at ground level (maybe another reason that Tiger Force aircraft were painted white)?
This is an interesting read on the problems of the R-3350. The crews reckoned they were more likely to be killed by Curtiss-Wright, the engine manufacturer, than by the Japanese!
The B-29s Achilles heel, the R-3350
Edited by GliderRider on Saturday 10th October 00:07
I also discovered 'Pumpkin Bombs' today. These were dummy or high explosive filled Fatman bombs used for practice both in the USA and in combat over Japan.
It could easily have been a Pumpkin Bomb that was seen by the chap the OP described.
Pumpkin Bomb
It could easily have been a Pumpkin Bomb that was seen by the chap the OP described.
Pumpkin Bomb
GliderRider said:
I also discovered 'Pumpkin Bombs' today. These were dummy or high explosive filled Fatman bombs used for practice both in the USA and in combat over Japan.
It could easily have been a Pumpkin Bomb that was seen by the chap the OP described.
Pumpkin Bomb
Added advantage would have been being able to move Fatman around without raising any eyebrows.It could easily have been a Pumpkin Bomb that was seen by the chap the OP described.
Pumpkin Bomb
Steve
Dogwatch said:
Yes, if you have to abort the mission what to do with the "passenger" in the bomb bay does present an interesting dilemma.
When Grand Slam was first used it was too valuable to waste so if the crew had to abort, they had to bring the bomb back. Landing must have been enormous fun.Halmyre said:
Dogwatch said:
Yes, if you have to abort the mission what to do with the "passenger" in the bomb bay does present an interesting dilemma.
When Grand Slam was first used it was too valuable to waste so if the crew had to abort, they had to bring the bomb back. Landing must have been enormous fun.JuniorD said:
Going back to the original post, surely this guy would have been able to ID the make and model of the alleged white aircraft?
Especially as he reckons it was bigger than a B-29 and there wasn't anything bigger than a B-29 at that time 
He was a marine though........so again, hardly a 'reliable' source of aircraft recognition
aeropilot said:
Especially as he reckons it was bigger than a B-29 and there wasn't anything bigger than a B-29 at that time
He was a marine though........so again, hardly a 'reliable' source of aircraft recognition
The B-32 Dominator was in-theatre at the time and went on to perform reconnaissance missions immediately after the Japanese surrender. With its massive fin, nearly 5 feet taller than that of the B-29, perhaps the Marine thought it was a larger aeroplane?He was a marine though........so again, hardly a 'reliable' source of aircraft recognition
This picture of the B-32 from the American 'National WW2II Museum' is captioned as being on Tinian:
aeropilot said:
The 32 x Lanc B1 Specials built specifically to drop the Grand Slam's were lightened by removal of the front and mid-upper turrets, as well as the H2S radar system and had more powerful Merlin 24 engines fitted, as well as the bomb bay mods to carry the bomb. They also had specially modified and strengthened undercarriage to enable them to land back with the bomb on board. Barnes Wallis had designed the bomb to be dropped from 40,000ft for its maximum destructive effect, but the problem was even the modded B1 Special Lancs could barely get to half of that height, and operationally, the ones that were dropped in the last few months of the war were dropped from around 12-15,000ft.
That doesn't make sense. It would be achieving terminal velocity way sooner than 40,000ft, and given the limitations of free-fall bombs and the relatively precise (but by no means precision) needs of the Grand Slam, it seems peculiar to assume a release height of 40,000 ft.GliderRider said:
Taylor James said:
Nothing changes. One man working and thirty standing around watching.
The guy on the platform is USAAF, the rest are Marines waiting to see the bomb get loaded aboard. Evanivitch said:
That doesn't make sense. It would be achieving terminal velocity way sooner than 40,000ft, and given the limitations of free-fall bombs and the relatively precise (but by no means precision) needs of the Grand Slam, it seems peculiar to assume a release height of 40,000 ft.
Good point. Maybe it was to get the spinning up to speed?Either way, I’ll not question Sir Barnes.
Yertis said:
Evanivitch said:
That doesn't make sense. It would be achieving terminal velocity way sooner than 40,000ft, and given the limitations of free-fall bombs and the relatively precise (but by no means precision) needs of the Grand Slam, it seems peculiar to assume a release height of 40,000 ft.
Good point. Maybe it was to get the spinning up to speed?Either way, I’ll not question Sir Barnes.
And in the first test of the Grand Slam bomb, dropped from 16,000ft., it attained the designed speed of just over 700mph.
Barnes Wallis was well aware of the performance of British bombers at the time (see Wellington), and proposed a new 6 engined design to reach the required 40,000 of his original earthquake bomb.
Barnes Wallis was well aware of the performance of British bombers at the time (see Wellington), and proposed a new 6 engined design to reach the required 40,000 of his original earthquake bomb.
CanAm said:
And in the first test of the Grand Slam bomb, dropped from 16,000ft., it attained the designed speed of just over 700mph.
Barnes Wallis was well aware of the performance of British bombers at the time (see Wellington), and proposed a new 6 engined design to reach the required 40,000 of his original earthquake bomb.
The Victory Bomber, model of it is at Brooklands.Barnes Wallis was well aware of the performance of British bombers at the time (see Wellington), and proposed a new 6 engined design to reach the required 40,000 of his original earthquake bomb.
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