Spitfire TR-9 in flight trim / elevator position (in flight photos)

[ZachariasX]

Some nice videos about the P-51 trim over different airspeeds have been posted by @Agathos_Deimon.

 

I took a moment to review some footage I have from the inboard cameras. They are of limited quality, as rolling shutters and vibration don't mix too well. Anyway, it was actually a first time that I took a close look at the elevator position during the flight and I must admit, some of it came as a surprise to me.

 

It is of note that the TR-9 and the combat ready Spitfire Mk.IX most likely do not have an identical CG position, same as civilian Mustangs and TR-51 can differ. Guns and ammo are removed, but in this bay in front of the wing spar are now two fuel tanks. The cockpit is moved IIRC 14 inch to the front to allow the installation of a back seat.

 

In my impressions about flying the TR-9, I commented on how little trim change it had over the speed range between ~120 mph to ~320 mph. This is true, as the elevator positions show, but it seems I was a little off about flairing her out during landing.

 

First, takeoff:

As the plane came off the ground, climbing at ~140 mph (+8 boost, 3000 rpm), you can see that the elevators tips have already a prononced upward position, making the elevators in a downward position. They will remain so for most of the flight and give you the "center position" of your control column. Raising gears does nothing to your trim at all.

 

As soon as you level out for flight, you trim her forward to not have any build up on control force at higher speeds. As it was difficult to observe the trim knob in the backseat, I can't say how trim was applied exactly, as I was not in control at this moment in flight. But in effect it makes her "hands off" (you don't want to do that, you always have to correct her attitude) for the remainder of the flight.

Here, around 270 mph IAS, you can see there was no change in elevator position. It is remarkable that in contrast to other planes, where with speed increase the center position of the stick creeps forward, it the Spit, it just doesn't.

 

Even when going faster, here, about 320 mph the elevator position shown here is actually the one of a slight pull out from a dive that is maintained though a slow barrel roll.

Any drop og G force to 0 g or lower immediately leads to a complete drop in oil pressure. They say it takes about 10 seconds to make her a glider, but nobody wants to find out and hence is VERBOTEN! to try so.  There is no trimming required doing wingovers and dives. She's just a darling.

 

Now coming back to the pattern, slowing down to 120 mph:

We're right next to Biggin Hill now, still doing about 130 mph.

 

Now the moment we pop the flaps:

It takes a second or so for them to deploy, and in this time you have to pull back about 2 cm on the stick to give you the picture above. This is basically THE significant trim change of the whole flight.

 

Coming in for landing and slowing her down, you get the impression of actually pulling back significantly on the stick. We just crossed the runway edge at around 90 mph or probably less.

The elevator in now for the first time (as far as flight configuations are concerned, not maneuvering) centered! Notice that the Spit is landed on one wing to counter the crosswind and keeping her nose straight down the runway.

 

This is the moment she sits down.

The stick is now way back compared to what you are used in flight.

 

We can see, the Spit has a very unusual trim that by no means is intuitive or trivial to reproduce. These birds can be very unusual.

 

[JtD]

It may not be intuitive or trivial, but it is well known and documented and was done like this already in Il2:1946 (within in limits of that engine).

 

Thank you for the pictures, different perspective and different from charts.

Edited December 23, 2019 by JtD

[Guest deleted@50488]

Yep,

 

have long been calling the attention of the devs with pictures and even video at other posts in this forums...

like this one recently: 

Nothing updated yet ? but I know dev team is small and this is a chosmetic detail more than a FDM issue, and I did send Gavrick a PM and he acknowledged it long ago and told they would look at it when a slot is available...

Edited December 24, 2019 by jcomm-il2