Hi Clarence! @jagmkx

I took some flying lessons long ago plus, my Dad was a fighter & dive bomber pilot during WWII, so I'm crazy about aircraft. Generally speaking, when an aircraft is parked, the control surfaces will be in the neutral position. I've never heard of control surfaces - ailerons, vertical stabilizer, & elevator or horizontal stabilizer ever drooping because of a hydraulic problem, but I suppose it's possible. WWI aircraft almost always had their elevator (horizontal stabilizer) in the down position when parked due to gravity. Back in the earlier days of flying, all those control surfaces were mechanically moved by wires. rods & pulleys, Therefore, the control surfaces could be in an other-than neutral position. If the stick was angled to the left, the right aileron would be down & the left one is up. The pedals usually ended up neutral because most pilots' legs are the same length. To go down, the stick or wheel is pushed forward; to go up, the stick is pulled back toward the pilot. When the stick is angled right, the right aileron is up & the left one is down. That is pretty much the rule all the way up to modern times when some of the planes have elevons, for instance, and other computer controlled surfaces that function slightly differently. But it's still pretty much the same ... to turn left, move the stick left - or turn the control "wheel" left like a car ... and so on. Some had springs which brought the stick to a neutral position.

I hope this helps!

That is a great question, Clarence (@jagmkx). My wife and I are both retired C-141 pilots and it generated quite a bit of discussion between us. There are a lot of variables here.

First, if there is a direct mechanical linkage from the controls to the ailerons, they will deflect in the opposite direction. I flew T-37s for 8 years, and my wife flew T-41s for 4 years, both of which had mechanical linkages. Both have mechanical locks on the controls to prevent the controls from flapping in the wind.

The second case is an airplane that has hydraulic controls, where you have hydraulics that actually move the ailerons. When the plane is not powered, there isn't any hydraulic power to the ailerons. Most hydraulically-powered planes have control valves that trap the hydraulics when the power is off. This prevents the ailerons from banging around in a high wind and damaging themselves. Both of us remember going out to C-141s to preflight them and finding both ailerons deflected down an inch or so. This was probably due to aging valves and the like. When the ailerons were powered, they always moved in opposite directions.

A whole other question would be about differential deflection of ailerons, where the ailerons deflect up and down a different number of degrees. Also, if you ever deal with a delta wing, you start talking about elevons, which combine the ailerons and elevators, which is a whole different deal.

Anyway, back to your original question. You would need to find out about the system that powers the controls on the plane you are modeling. If it is mechanical, the ailerons should be deflected in opposite directions. If it is a hydraulic control-system, then it might be possible to droop down if they didn't have check valves. I usually don't want to learn that much about the planes I am building, so it is always safe to streamline the ailerons with the wings, and don't put them up or down.

Ditto with all Gents' points above, my friend @jagmkx!
Yes, the surfaces that are kept "neutral" with only hyd pressure will sooner or later droop down after engine shutdown (this will include air brakes and so on, like the, say, F-5A ventral air brake).
As always, having pictorial evidence of your intended posing will be a blessing.