P-51 Landing Gear Door Close at Start Up

[Broncazonk]

Notice how the landing gear doors on the P-51 Mustang close when the engine starts? The gear doors are down (open) when the engine is switched off, but when the engine turns over for the next cycle, the door automatically closes. And then, when the gear comes up, the doors open again (of course) and then closes. Why do the gear doors close at start up?

Bronc

[RSwank]

The doors are hydraulically operated. When the engine shuts down the doors fall open under their own weight. When the engine starts and builds up the hydraulic pressure the doors close.

[Kutscha]

[Tony Kambic]

I was told a long time ago, that the inner gear doors come up to provide a clear path for the radiator scoop. Somewhat hard to believe, as startup and taxing may not be such a big deal. But facing into the wind for a run up, and then for takeoff with these doors up there is no obstruction.

I have read that once parked and engine shutdown, that an emergency release for these inner doors is pulled, which releases the doors to open, and in the situation, then an interlock prevents the landing gear handle from accidentally being raised while parked, thus preventing collapse of the gear. It must be returned to original position for flight else no hydraulic pressure is brought to the gear or flaps.

Tony