B25 v B17 bomb doors.

There could be many reasons from airflow loads on them requiring different gearing though to effecting the aircraft trim when opened or closed..

I think it was the Hampden or Whitley that the doors opened by the weight of the bombs dropping on them then shut again by rubber bungies…… I kid you not!
Simple and effective.

Thanks for the replies, very interesting. Often wondered why the doors on the B25 at Dunsfold open instantly.

To expand the discussion to other aircraft. Does the He111 and Blenheim have bungy sprung bomb doors?
The film BoB shows bombs pushing open the doors as they fall past and I’m sure I’ve seen a film of a Blenheim crewman pulling open the doors of a Blenheim?

He 111 used coil springs so the bomb could push them open.

HOWEVER there was also a method to crank open the doors as well.

Thanks for the replies, very interesting. Often wondered why the doors on the B25 at Dunsfold open instantly.

To expand the discussion to other aircraft. Does the He111 and Blenheim have bungy sprung bomb doors?
The film BoB shows bombs pushing open the doors as they fall past and I’m sure I’ve seen a film of a Blenheim crewman pulling open the doors of a Blenheim?

BTW, the Anson’s spring-driven bomb door action is very fast – with camera set to 3 frames per second, I’ve only got one frame on other than closed position when it’s done the cardboard bomb drop at NZ airshows.

it is a very fine screwjack on the B17. The speed of the B25 is such that you have to make sure people are not in the way!

B-17 bomb door actuation (looking aft): screwjack to lefthand door on the right, grey shaft on the left drives the gearbox, which in turn drives the two shafts to both door screwjacks.
[ATTACH=CONFIG]240703[/ATTACH]

Similarly you don’t want to be throwing the comparatively large doors of the B-17 around too quickly, you’d need to enhance the strength of the doors and their hinges. Less important on the small doored B-25

I would hazard a guess that the Mitchell didn’t really have a need for fast acting bomb bay doors, but the end result turned out this way because of:
– the choice for hydraulic actuation by the design team, this was used on the gear, flaps, brakes, cowl flaps as well (in contrast to the B-17’s fully electric systems)
– the limited room beneath the front spar to fit the mechanism. This may have led to the mechanical lever arrangement.

A heavy bomber of the period had little need for fast acting bomb doors. Not sure why the Mitchell had.

B-25: hydraulic actuator with a mechanical lever arrangement which amplifies the motion.
B-17: electric motor driven, IIRC with a screwjack arrangment.

In short, totally different design solutions.