Doolittle Raid - B25 Flap Settings?
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Doolittle Raid - B25 Flap Settings?
I have just seen a TV programme about the carrier-based raid in which there were several references to 'full flap' being used for take off. The first time I heard it I thought it might be a slip of the tongue, but it was repeated - and eventualy I saw a clip of a B25 staggering into the air from the deck of 'HORNET' with what looked like about 60 degrees of flap.
So I guess 'full flap' was indeed used. But why? Simplistic view suggests best L/D ratio, important to help the guys get airborne in a reported 400 feet (!), is usually available at rather less than full flap deflection. Was a lower flap deflection available on the B25? These people were neither suicidal nor stupid, so there must have been a good reason for the choice. What trials, if any, were done during the work-up to establish the best configuration? Is there anyone still around who can even answer that question?
It's one thing to have a nice QFI-ish argument about what flap to use for best takeoff performance. It's quite another to drag an overloaded B25 off a pitching flight deck for a one way mission. Glad I didn't have to do it (and glad we had guys who were willing to). Mind you, I have dragged a Victor K1 off the ground at Gan with a full fuel load at temperatures in the 30s . . . . .
So I guess 'full flap' was indeed used. But why? Simplistic view suggests best L/D ratio, important to help the guys get airborne in a reported 400 feet (!), is usually available at rather less than full flap deflection. Was a lower flap deflection available on the B25? These people were neither suicidal nor stupid, so there must have been a good reason for the choice. What trials, if any, were done during the work-up to establish the best configuration? Is there anyone still around who can even answer that question?
It's one thing to have a nice QFI-ish argument about what flap to use for best takeoff performance. It's quite another to drag an overloaded B25 off a pitching flight deck for a one way mission. Glad I didn't have to do it (and glad we had guys who were willing to). Mind you, I have dragged a Victor K1 off the ground at Gan with a full fuel load at temperatures in the 30s . . . . .
I think it probably came down to the fact that with full flap,plus wind over deck then the front aircraft needed to get airborne in a `reasonable` attitude` so they didn`t clout the tail/fins on the deck as they left the ship.Most aircraft have a much lower `attitude` with full flap,and also usually a lower stalling speed.Once clear of the deck then one would gradually raise the flaps. I`m sure J D had given it a bit of thought and tested it out beforehand..
ATA Pilots Notes for all marks of Mitchell say max of 45 degrees. Normal take off flap 15-30 degrees, safety speed 150 mph. The notes say that sometimes the flaps are calibrated in fractions ie 1/3 = 15 Deg, 2/3=30 deg, etc
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From GENERAL DOOLITTLE's after action report.
HyperWar: Tokyo (Doolittle) Raid: After Action Report of Col. Doolittle
Concentrated courses of instruction were given at Eglin Field. The instruction included carrier take-off practice under the supervision of Lt. Henry Miller of the U.S. Navy. This practice was carried out on one of the auxiliary fields near Eglin. White lines were drawn on two of the runways of this field. Take-off practice was carried out with light load, normal load, and overload up to 31,0000 lbs. In all cases the shortest possible take-off was obtained with flaps full down, stabilizer set three-fourths, tail heavy, full power against the brakes and releasing the brakes simultaneously as the engine came up to revs. The control column was pulled back gradually and the airplane left the ground with the tail skid about one foot from the runway. This appeared to bet unnatural attitude and the airplane took off almost in a stall. In spite of the high wing loading and unnatural attitude the comparatively low power loading and good low-speed control characteristics of the airplane made it possible to handle the airplane without undue difficulty in this attitude. Only one pilot had difficulty during the take-off training. Taking off into a moderately gusty wind with full load, her permitted the airplane to side slip back into the ground just after take-off. No one was hurt but the airplane was badly damaged. While we do not recommend carrier take-off procedure for normal take-offs, it does permit of a much shorter take-off, and may be employed in taking off from extremely short or soft fields. With about a ten-miles wind take-offs with light load were effected with as short a run as 300 feet. With a normal load of 29,000 lbs. In 600 feet, and with 31,000 lbs. In less than 800 feet. The tact, skill and devotion to duty of Lt. Miller, of the U.S. Navy, who instructed our people in carrier take-off procedure deserves special commendation.
HyperWar: Tokyo (Doolittle) Raid: After Action Report of Col. Doolittle
Concentrated courses of instruction were given at Eglin Field. The instruction included carrier take-off practice under the supervision of Lt. Henry Miller of the U.S. Navy. This practice was carried out on one of the auxiliary fields near Eglin. White lines were drawn on two of the runways of this field. Take-off practice was carried out with light load, normal load, and overload up to 31,0000 lbs. In all cases the shortest possible take-off was obtained with flaps full down, stabilizer set three-fourths, tail heavy, full power against the brakes and releasing the brakes simultaneously as the engine came up to revs. The control column was pulled back gradually and the airplane left the ground with the tail skid about one foot from the runway. This appeared to bet unnatural attitude and the airplane took off almost in a stall. In spite of the high wing loading and unnatural attitude the comparatively low power loading and good low-speed control characteristics of the airplane made it possible to handle the airplane without undue difficulty in this attitude. Only one pilot had difficulty during the take-off training. Taking off into a moderately gusty wind with full load, her permitted the airplane to side slip back into the ground just after take-off. No one was hurt but the airplane was badly damaged. While we do not recommend carrier take-off procedure for normal take-offs, it does permit of a much shorter take-off, and may be employed in taking off from extremely short or soft fields. With about a ten-miles wind take-offs with light load were effected with as short a run as 300 feet. With a normal load of 29,000 lbs. In 600 feet, and with 31,000 lbs. In less than 800 feet. The tact, skill and devotion to duty of Lt. Miller, of the U.S. Navy, who instructed our people in carrier take-off procedure deserves special commendation.
Gentleman Aviator
Most interesting to see the pragmatic approach of lines painted on runways and "suck it and see."
Much better than getting QFIs to argue about it!
(and me an A2 ......
)
Much better than getting QFIs to argue about it!
(and me an A2 ......)
