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shifted flight controls


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Greetings,

A gifted and generous gauge maker created an XML gauge that allows the elevator and rudder to have a limited flight control surface throw when the flaps are retracted. The only problem with this is it reads the joystick axis and if the surface goes beyond the limit, the gauge brings the surface into limit and causes a control surface flutter. I would like to know if by modifing the fsuipc .ini file, could I create a "configuration specific" joystick axis calibration. When the flaps are retracted, the throw is 50% of the leading edge down on the elevator and 80% limited on the rudder. I tried to play with the joystick sensitivity and null point and got some of the flutter out but if I could limit the axis through a configuration specific calibration, I would never get a flutter. I hope this makes sense to you and appreciate your time.

Many thanx, Christopher Raison.

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The only problem with this is it reads the joystick axis and if the surface goes beyond the limit, the gauge brings the surface into limit and causes a control surface flutter.

I don't quite understand. Do you mean that the gauge is letting the joystick values through to FS, and only then changing them? If so, then, yes, I would imagine that would give a very unstable effect.

I would like to know if by modifing the fsuipc .ini file, could I create a "configuration specific" joystick axis calibration.

Well, no, this is not currently possible. You can have separate calibrations for different aircraft, but not for different settings on a single aircraft, dynamically changed. Actually, I don't really like the thought of that in any case -- you would have to be sure to have the elevator and aileron more or less centred when changing from no flaps to flaps or vice vera, or face a severe risk of losing control because of the sudden drastic change in the control surface positions.

Additionally, if FSUIPC were limiting the values through a different calibration, what would your special gauges be doing? Are they reading the joystick axis at source? It sounds unlikely, as if they were they could modify the input to FS so that you wouldn't get the fluttering in the first place. If they are only monitoring the resulting surface positions then FSUIPC's calibrations would have already occurred, so the gauges' actions would double the effect.

No. It seems to be that the only solution is for the gauges to intercept the axis controls en route to FS, modify them as needed, then pass them on. Then you'd not get the fluttering. If using FSUIPC calibration you'd then need to be sure to calibrate with flaps up.

Maybe I'm misunderstanding you in the first place. If so, apologies. I'm not even sure why you'd want any of this in any case, but I assume it is something to do with the incorrect behaviour of a particular aircraft? With many airliners the main effect of flaps on control sensitivity applies to stabiliser/elevator trim. For instance, on the 737 the trim should be operating twice as fast when any flaps are down -- you can actually see the trim wheels spinning faster when electric trim or autopilot trim is performed.

Regards,

Pete

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Pete,

Thank you for your input. This is what I am trying to achieve with the XML gauge. The A-6 Intruder had shifted flight controls as in, when the plane is on approach you need greater stab and rudder throws because of the low approach speed with the flaps extended. The stab had a range of 24 deg NU and 1.5 deg ND. The rudder's range was 35 deg. Then the plane is at high speeds you don't want to have that great of a range because the airframe will overstress, stab at 9.5 deg NU and 1.5 deg ND and the rudder at 4 deg. What the guage does, from what I understand is that it limits the surface by monitoring the elevator axis of the joystick and if the limit is reached or exceaded the gauge brings the surface back to the limit and this causes the flutter. What I would like to see is only the NU and rudder values on the calibration to change. I did an experiment with the fsuipc .ini and cut the negative value in half for the elevator axis and 80% on the rudder axis. This provided the correct throws without changing any of the aircraft files. I don't know if I have explained my problem better, If there is no solution, I guess I will have to live with a little flutter.

Many thanx, Christopher Raison

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... it limits the surface by monitoring the elevator axis of the joystick and if the limit is reached or exceaded the gauge brings the surface back to the limit and this causes the flutter.

Yes, and because it is allowing the higher values through and only THEN changing them, there is absolutely no way you can fix that. The gauge needs to be written so that it traps the joystick inupt and modifies it before FS sees it.

What I would like to see is only the NU and rudder values on the calibration to change. I did an experiment with the fsuipc .ini and cut the negative value in half for the elevator axis and 80% on the rudder axis. This provided the correct throws without changing any of the aircraft files.

Yes, but it cannot change dynamically. Your gauge is trying to do that. You can't do both in any case. It would be best to write the gauge correctly in the first place. I cannot see any other way.

I don't know if I have explained my problem better

It is exactly as you explained before, but it still makes little sense to recalibrate any axis suddenly in mid-flight just because of a flaps change. You would have a sudden change of surface positions as a result, as I explained, and probably lose control. If your gauge is meant to do this limiting slowly, gradually, then that is fine, but it needs to do it BEFORE FS sees it, not after, otherwise you are bound to get your flutter.

In my opinion you would be much better off simply using one of the flattened-centre FSUIPC calibration slopes, so mostly you have less severe effects for most of the movement but are still able to reach the extrmes when needed. It is exactly for the sort of control variations you are describing that these facilities were added.

Regards,

Pete

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