When the stang is parked, are the inboard weel well doors up or down?
When the engine is running they are up, once the engine is shut down the hydraulic pressure slowly bleeds off and eventually they come completely down
Depends on how long its been parked. Hydraulic pressure held them closed for a while. After the pressure drops they would droop until opened.
Both the flaps and wheel doors fell, not just the doors. If one is down the other has to be.
Wasn’t that true only for the P-51 B & D. I think the P-51 and P-51A had some form of up lock that kept the inner doors in the closed position when on the ground.
Actually, it’s designed that way. If you have a good hydraulic system in your aircraft, it will retain the pressure it had when shut down until something is done to release the pressure. And if the aircraft is parked in the sun for some time the heat absorbed will cause the hydraulic pressure to increase until something releases it. Most hydraulic systems have what are called thermal relief valves which automaticly releave the pressure when it reaches a predetermined pressure (usually about 300 to 500 psi above the normal operating pressure). Other wise the pressure will continue to rise until a line breaks or something else in the system fails.
For some reason from the D model on, NAA built the aircraft without thermal relief valves (there was no hydraulic hand pump either - the manuals for the aircraft show it stowed in the port wing tip for the maintenance personnel to use). In order to prevent pressure build up in the hydraulic system on the ground after shut down, a manual by-pass valve was installed which was operated by a red T handle on the rh bottom of the pedestal. The pilots operating manual called for the handle to be pulled out during the shut down procedures and to be pushed in immediatly after starting the engine (believe me, if you don’t push it in, you don’t get any hydraulic pressure). Depending on how tight the components are,it can take up to 24 hrs for the flaps and gear doors to fall completely. And they come up immediatly when the pressure is applied to the system after start up. (note, the flaps drop together while the gear doors drop at different rates which vary from aircraft to aircraft)
If you look at enough pictures of the Stangs in flight, you’ll see that a lot of them had the inner doors removed. I’ve never modeled one that way however.
Regards, Rick
Ummm… let me ask another way; You set up your approach, lower the gear lever in the cockpit, opening both inner doors, then the gear goes down… Do the inner doors close back? And if I understand the discussion, they remain closed for a period of time until the hydraulic pressure bleeds off?
Hmmm… I always thought the inner doors were raised / lowered by the tire pressing against a lever on the inner gear doors… Naa, wait a minute, that was the big, electronic, transparent Monogram P-51! [:o]
Very interesting, because I always wondered how the inner doors should be posed with the gear down.
Take care,
Frank
Yes, they close after the gear comes down to clean up the aerodynamics, and then bleed down with hydraulic pressure when parked
Thanks! [tup]
Frank
Ok now we have that figured out, why did they choose the ignition system the way did for that thing… Rrrrrrrr… Rrrrrrr… Rrrrrrrr (puff of white smoke then nothin) Rrrrrrr…Rrrrrr (another white puff and the blades turn about 1 inch, then nothing) Rrrrrr… Rrrrrr (then a lotta white smoke a few coughs, a stutter to make you think it wasnt going to switch over then…) RRRRROOOOOOAAAAARRRR! [soapbox][:-^]
[:-^]…ok…gonna throw a wrench in the works here…
it’s my understanding that the NA-73’s through the “A’s” and into the early “B” production run, the inbd gear doors were mechanical therefore remained closed after the gear was cycled through for landing regardless of hydraulic pressure…unlike the flaps which did bleed down…
this is from conversations with mustang afficianadoes and their experiences and not from a tech manual…
somewhere into the early “B” production run the gear became hydraulic and as long as there was specific hydraulic pressure maintained…the gear as well as the flaps remained in the stowed configuration…
there is a company that has produced books on the technical aspects of specific aircraft…i believe called “High Tech”…
'nuff said…i hope i’ve not confused the matter…too much…
So if a p-51D is parked for any period of time the flaps and the inner doors are down.
For the model to be correct , eather the doors are removed and the flaps are down , or both the doors and flaps are down? Then I have to cut and repostion the flaps in the down postion to be in the true configaration of a parked P-51D. the doors also have to be down…
Now that I have the wings in place do I cut and repostion them of put the inner doors up?
A little help Please as it is my first build in a GB. Thank you…
Glen S
A P-51D that has been parked long enough for the hydraulics to bleed down would have both the inner doors & flaps drooped down. Otherwise, both would still be up. I assume you’re building the Hasegawa kit, since the Tamiya kit gives you the option of dropped flaps. If you have already assembled the wings, dropping the flaps is not a good idea unless you are highly skilled at such surgery. Should have been done before you assembled them. You could do what Pix is doing on his build & assemble the wheel bay doors in the up position. Or you could just ignore the innaccuracy & show the doors drooped with the flaps up. Unless you are building for a contest, it really isn’t that big a deal.
Regards, Rick
Thanks Rick
I think you solved the problem for me . just have the doors slightly open and not have to worry about how much as each drop at a different rate. I really did not think about the doors or the flaps while I was puttin them toogether. Just found the artical today.
Glen S
There is a good reason the gear doors closed again when the wheels came down. And why this feature appears on aircraft long after Mustangs. In WW II, operating from grass and mud and generally crappy airfields in the Pacific and other theaters, you had to do everything possible to keep from getting FOD (Foreign Objects and Debris, or Foreign Object Damage) from getting into the fine workings of the airplane. Those big doors yawning open during the first stage of flight invited everything from dirt clods to birds getting in there. Even on good, concrete or tarmac fields, there are plenty of nuts, bolts and pieces of gravel to worry about.
Ok, if I build an “A” or very early “B”, I have always to fix the inner doors in the closed position?!