F-15 always Pitching up

[pauldy]

This has been bugging me for some time now.

 

The F-15 in Lock On will always want to pitch up, no matter what the throttle settings are and even with speedbrake deployed and decelerating..

Unless i use the auto pilot, the plane's bound to go higher & higher~

 

This constant pitching up gets annoying at times..

 

Anyways enough rant~ all i want to know if this is another known Eagle Disease.

 

 

I doubt my joystick has a problem because i can make the a-10.. or any other plane (except the Frogs, haven't tried..) fly level without the use of Autopilot..

:)

Edited October 6, 2009 by pauldy

[Vekkinho]

FLCS failure?!

[pauldy]

No failures set whatsoever.. no damage..

[Udat]

Try disconnecting your joystick and fly using keyboard to rule it out of the equation.

[OldCrow]

I think I have the same problem, like when the speed decrases, the angle of attack increases (without toutching the controlls) to stay level. Its the total opposite of what you would expect, as all other planes in lockon behaves the opposite, so my guess its some electronics shit in the real plane that tries to controll the plane for you or something, but I know far too little about the F-15 to know..

[pauldy]

I tried testing the keyboard. The inputs might be more unrefined but i tried the diving down with the speed brake deployed..

 

The plane still pitches up even though it's decelerating.

 

Maybe there's something in aerodynamics i don't know but isn't the plane supposed to maintain constant nose while the descent rate increases?

 

Even though i'm slowing down the FPM continues to go up..

 

 

 

Then i tried the constant speed & Altitude test.. i've set the throttle for a constant 350 knots indicated at 25,000 feet. First i engaged altitude hold to set the horizontal stabs for a constant altitude.

 

After disengaging the Auto Pilot, the f-15 started pitching up little by little even though i didn't touched the keyboard.. i wasn't accelerating either...

 

Accelerated the time compression, the f-15 continued climbing up until it was too high and too slow, hence stalled off the sky..

 

If i read correctly the F-15's supposed to have that Pitch trim Compensator/Control Augmentation System. A system supposed to keep the plane level as much as possible, not pitching up.

Edited October 6, 2009 by pauldy

[hannibal]

sounds like you got auto pilot on.... does ALT HLD appear on hud?

[pauldy]

No, I actually engaged the auto pilot initially so that the aircraft would be set for a level flight.

 

Then I disengaged the autopilot so that the Horizontal stabilizers would be trimmed for a level flight..

 

Even after disengaging the autopilot, the aircraft continued pitching up little by little whereas it should either maintain level flight, climb or descend depending on the throttle changes...

 

or at least that's what i think.

 

btw.. What i mean by "pitching up" is that the Flight Path Marker/Tadpole on the HUD of the F-15 WILL continue to GO UP slowly as if there was an increase in engine power even though i haven't change the throttle settings. Not an abrupt pitch up like the ones in Take off or Air combat..

Edited October 6, 2009 by pauldy

[CHola]

The F-15 in Lock On will always want to pitch up, no matter what the throttle settings are and even with speedbrake deployed and decelerating..

Unless i use the auto pilot, the plane's bound to go higher & higher~

This constant pitching up gets annoying at times..

Anyways enough rant~ all i want to know if this is another known Eagle Disease.

 

F-15 pitches up due the shift of Center of Pressure (or CG, for calculating purposes), so nose pitching up indicates a reflex-cambered wing on F-15. Try trimming the plane every now and then.

F-15 isn't CCV, so it requires trimming.

[pauldy]

so does it mean the f-15 will always pitch up & down from a given altitude?

 

The problem i encounter when trimming the f-15 is that, the aircraft can only either go up or down.. no level flight when i trim.. regardless of the speed, pitch corrections or throttle settings..

Edited October 6, 2009 by pauldy

[CHola]

Dunno. I fly by mouse and I don't need trimming at all.

 

However, you should be able to achieve Vspeed=0, with given trimming range. You can check, if your trimming input is working by going to external view while trimming. If elevators move then it's just a matter of finding a right position for given speed.

However, once you accelerate or decelerate, you'll need to trim again and after the autopilot, trimming is mandatory, too. Trimming is a full time job, on nonCCV aircraft.

 

Short of that, your joystick may be malfunctioning.

[pauldy]

Ok, i just want to know something..

 

Any users here of Saitek Cyborg Evo or St290? I just wanted to verify if the F-15 can't stay put or level off when you use the said joysticks..

 

I think it just doesn't make sense this pitch up action only happens in the F-15 and no aircraft else.. and that even though i already had deadzones set in game doesn't eliminate this..

 

though, I think i remember a post about an F-15 wishlist wherein the trimming also had problems. Maybe this is the problem that was pointed out in that list..

[Sanch0]

I think it will be better if you record a track.

[pauldy]

I made a track file

 

In that track, initially i wanted to achieve a constant speed of 350 knots at 25,000 feet

 

i then made some throttle adjustments and was able to maintain 350.

 

Just watch how the FPM ALWAYS goes UP even though i haven't adjusted anything, not the stick, not the trim... and the VSI just confirms it too..

creeping up to positive climb rates.

 

On the latter parts, I remember trimming down and adjusting the airspeed to compensate for the pitch up.. That's not the case for this F-15. As you see i was already in Burners, increasing airspeed while the plane still continues to pitch down further~

 

The Trim doesn't seem to do anything because it will just cause the plane to pitch up or pitch down.. it never levels the plane.

 

On the last part i was descending with the speed brake deployed. It's clear on the HUD that even though i'm decelerating, the F-15 still continues to pitch up which i find odd.. Shouldn't the FPM go down instead?

 

At any rate if.. this is really a established problem in the F-15 in-game, Hope this will get

fix in that 1.13 patch (if it even sees the light of day) because this is starting to be a nuisance.

 

 

I don't experience this kind of problem with other planes in Lock On nor in any other Sim that i currently play.. I doubt my joystick has a problem.

Edited October 10, 2009 by pauldy

[CHola]

pauldy, the way to test the trim is to put the plane on "speed hold" autopilot mode, key "J". Then you can test trim, properly.

BTW, does "Attitude Hold" autopilot mode (Key "H") works correctly?

 

Ok, just saw your movie and the plane is behaving perfectly normal. The plane is pitching down during acceleration (not up as you said), indicating positive cambered wing. Either way, real plane never flies dead zero Vspeed and oscillations you experience are normal. It's strange, if you don't experience such behavior in other planes, though.

Edited October 10, 2009 by CHola

[pauldy]

@CHola: Yup, the Auto Pilot modes work correctly. I never used the Speed hold much though. Tried it but it was pretty much the same in that track file.

 

when i was diving down with the burners on, i had already trimmed down.

My Trimming down of the plane caused it to dive down. I have not really moved the stick at all.

I was hoping the decreased/negative trim while accelerating would keep the nose from rising off the level horizon

 

btw way what's this Positive camber wing? Is that the reason why the F-15 has the tendency to pitch up?

Edited October 10, 2009 by pauldy

[pauldy]

I made another track, this time focusing in the trimming.

I throttled for 350 knots again then leveled off using the "H" key.

I then disengaged the Autopilot and trimmed down. You can see the stick going a bit forward too because of the trimming.

 

The F-15 continued started to pitch down after the trim change.. I then engaged the burners hoping the increase in speed would somehow make the plane go up again but no.. the Plane still continued pitching down..

 

I was able to have a positive rate of climb again by trimming up.

[CHola]

Positive cambering is a way to fabricate the wing to make it have some degree of lift even when at alpha (AoA) 0°. Such wings pull the nose down when accelerating, since the Cp (lift point) moves backs, behind CG (center of gravity) as the alpha and Cl (lift coefficient) decreases.

During acceleration in flight, a pilot (you) of any but CCV (Control configured vehicle = FBW) aircraft needs to either push stick forward permanently, or keep trimming the aircraft if he chooses to hold stick in constant position.

 

If your nose is going down, you should trim "nose up" (contrary to nose movement) to reduce the effect of Cp moving backward.

 

The trouble with any joystick (that I've seen) and that's why I fly with mouse, is the lack of continuous control input. Today's joysticks work like a flystick in F-16, but Falcon has a FBW computer which handles this automatically.

Other nonFBWed (mechanically controlled) aircraft don't have flystick which auto centers and the pilot can incline the flystick by 0.5° f.e. to counter a slight imbalance due wind blow, a different pressure air pocket, etc, much like you can do with mouse.

Same thing happens in LOMAC.

[pauldy]

Oh i see. It's pretty much the positive cambered wings of the F-15 as you said.

 

I never knew control sticks in real aircraft have to be inclined to maintain a more neutral and level flight.

 

I do remember the the F-15 wasn't a FBW aircraft, hence lack of those automaton responsibilities like in the F-16.

 

Thanks for clearing this up for me CHola :)

I'm practically clueless about aerodynamics and such.

 

Guess i'll just go with the work around of using the Autopilot modes when in cruise/non combat phases of a given flight.

[CHola]

Yes, that's just like driving the car.

You always need to make small corrections to maintain the driving direction. That's called "fling with your a$$", meaning fling upon the feeling, not by instruments, since those can't read such small variations.

Sometimes those inclinations are so small that are barely (if) visible, but try driving a car with locked steering wheel, even on a dead straight highway and soon, you'll end up outside the road.

Edited October 10, 2009 by CHola