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PostPosted: Sat 24 Sep 2016 15:25 pm 
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FAAMAN wrote:
As I'm sure others will also point out, the inner main landing gear doors on a P-51 usually remain closed when parked and only open during the landing gear retraction/extension sequence, occasionally one or both doors would droop open but not equally. I made the same error with my own P-51 builds.
FAAMAN has the right idea but having spent some time looking through photographs of P-51's my observation would be: with the gear down and engine running the inboard main gear doors are definitely retracted - observed from photos of aircraft landing and taxying - both modern and period images. I would say that it is 50/50 on the photos of aircraft stationary, engine off, again from both modern preserved aircraft and period aircraft photos. The hydraulics on these aircraft would tend to de-pressurise relatively rapidly and the doors fall open (probably moving slowly as the very act of drooping would cause some back pressure - I am sure an engineer would comment). This would suggest there is probably no up-lock on the doors.
From the modelling perspective, either/or seems the way ahead. Your own back story of 'just landed' or 'long since shut down' to suit.

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PostPosted: Sun 25 Sep 2016 06:34 am 
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Depending on the design of the hydraulic system and it's requirements, most aircraft hydraulic systems "bleed down" when the engines are not running. Gravity will always take hold if there are no locks, usually omitted for weight saving, and on the P-51 the landing gear oleos are uplocked, the outer door being attached to the oleo will then lock the inner door when closed.
Hope this helps :thumb:

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PostPosted: Thu 20 Oct 2016 08:42 am 
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I modelled mine down as I found a picture of NZ2429 parked in a hanger with her inner gear doors down, that was good enough for me.
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PostPosted: Thu 20 Oct 2016 13:43 pm 
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After reading the discussion of wheel doors, my 2c worth.

Unless the engine is running or the aircraft is recently vacated, the wheel doors probably want to be "down a bit", but not hanging vertically, and also not at the same angle because the pressure generally doesn't drop at the same speed on both sides.

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PostPosted: Thu 20 Oct 2016 19:51 pm 
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Up to the Mk.III B/C the doors were held closed mechanically by a cable. From the mid-D series they were operated hydraulically.
Thus on Mk.III B/C the main doors should be closed, on later versions they can be open or closed or anywhere in between.
But note; on the D and later the same hydraulics operated the flaps and they droped first. Thus flaps up = closed doors, flaps down= open or closed doors.

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PostPosted: Thu 20 Oct 2016 19:53 pm 
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Having been an aircraft mechanic, and having a great regard for my own opinion, I'd say that the hydraulic pressure keeps the gear doors all the way up until the crew chief pulls the handle that depressurizes the system. Then he or she would have to pull the door down to look up into the gear well to do the post-flight inspection. Getting the doors UP after they're down is not possible without pressurizing the system, which means running the engine (not going to happen, usually). So you'd pull the door all the say down to enable yourself and your assistant to safely move under the aircraft without having the gear door split your scalp or something. A door or prop that in an "unusual" position is an accident waiting to happen. You want the props to be a cross, with one blade pointing straight down. You want to gear doors to be down all the way or up all the way. In between is likely to cause injury if you're scooting around under the aircraft on your butt and you run into the door. Which reminds me of a story...

I recall that someone had left a tiny little access door on the F-16 open and I rushed by and it neatly sliced my scalp. I turned to an avionics guy and said "Am I bleeding?" He looked at me and was saying "no" when a bright red drop of blood ran down my forehead. He suddenly had the oddest expression on his face!

...and we wore onions on our belts, which was the fashion at the time.

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PostPosted: Thu 20 Oct 2016 20:53 pm 
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I've been going to Flying Legends pretty much since inception, so I've seen a fair few P-51s at various times during the day. If you do the flight line walk it's quite likely the doors will be fully down, probably due to a pre-flight/walk around at the start of the day, but sometimes they will be drooping. Drooping doors might be a smidge, they might be half open, but always asymmetric. When they taxi past to line up or recover the doors are always fully up.

On the topic of P-51s, has anybody seen the Airfix teaser today?

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PostPosted: Thu 20 Oct 2016 23:58 pm 
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peebeep wrote:
On the topic of P-51s, has anybody seen the Airfix teaser today?
Discussion here Paul :arrow:
viewtopic.php?f=51&t=49533&start=40#p748981

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