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fistius

B-29 Flaps

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fistius   

Hi guys, 

 

question on the B-29s flaps, would it be uncommon for them to be deployed on the ground? I know that B-17s generally wouldn't, just not sure about the Superfortress.

 

Cheers, Chris 

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nfiler   

Chris,

No, it would not be at all common. Flaps increase lift, allowing quicker take offs and slower approach speeds. Once on the ground on landing, that increased lift works against you by keeping the weight off the wheels, thus not allowing the brakes to work their thing.

They also tend to get dinged up by rocks and stuff thrown up into the flaps.

So the flaps are usually raised on roll out and left retracted on shut down. With big birds they also are a great head cracker if in the lowered position. On airplanes like the Mustang, with hydraulic flaps they tended to bleed down.

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fistius   

Cool, thank you very much. I wasn't sure if they sagged due to hydraulic pressure. 

 

Cheers, Chris 

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15 hours ago, fistius said:

Cool, thank you very much. I wasn't sure if they sagged due to hydraulic pressure. 

 

Cheers, Chris 

I'm pretty sure the B-29 (like a lot of other aircraft) has jackscrew driven flaps, so there won't be any sag/droop.

 

As mentioned above, once on deck, we'd bring the flaps up right after turning off the runway. Otherwise, they're down in various flight regimes or for preflight, post flight inspection/walk-around, and maintenance only.

 

I think aircraft look cool with flaps down. I have a 1/48 B-29 project in the works also, and have debated picking up a set...but I' think I'm just going to leave them up.

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dnl42   

I seem to recall the P-51's flaps were deliberately down on the ground.

 

The P-51's landing gear doors, on the other hand, look like they bled down since photos show them in various positions.

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nfiler   

Flaps and gear doors on the Mustang are hydraulic.

To prevent over pressuring the system due to solar heating that could damage seals, the hydraulic release handle on the lower right hand side of the instrument sub panel (behind the stick) was pulled after shut down. As the label sez, this released pressure in the system and as a result the gear bay doors and flaps would slowly bleed down.This could also occur if the a/c had a leaky hydraulic system.

As someone mentioned, the B-29/B-50/C/KC-97 all had electric motors that drove a jack screw to raise and lower the flaps. Thus no bleed down. They had to be raised or lowered intentionally.

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DonSS3   

As noted above, extended flaps help generate lift. Not necessarily something you want when the aircraft is on the ground. Think about a tied-down aircraft, a good wind coming directly from the nose, and the airplane trying to lift off...

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12 minutes ago, DonSS3 said:

As noted above, extended flaps help generate lift. Not necessarily something you want when the aircraft is on the ground. Think about a tied-down aircraft, a good wind coming directly from the nose, and the airplane trying to lift off...

Reminds me of that Boneyard 747 video clip

 

Edit:this one

 

Edited by mungo1974
vid link added

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