GWS P51D Mustang

[Hengheng88]

Does GWS Mustang got problem?
When i try to roll the plane, it will roll the opposite way and stall.
Does anyone got the same problem?

Heng

[randomtask]

Hi Heng Heng

It could be one of a few scenarios:

1.The controls could be reversed on your aileron channel. Check your controls on the ground before flight the next time you're at the field.

2.Adverse yaw which could happen at slower speeds. This happens when you input directional controls only with ailerons. Sometimes you may need to couple your aileron controls with the ruddder.

Hope This helps.

Cheers
RandomTask

[madflurry]

it rolled the other way?! you mean when you push ur tx stick left it rolled right?? then i think you need to reverse that channel.

[Hengheng88]

it rolled the other way?! you mean when you push ur tx stick left it rolled right?? then i think you need to reverse that channel.

Let say u wan the plane to roll right, it roll right and do a hard roll left.

[Hengheng88]

Hi Heng Heng

It could be one of a few scenarios:

1.The controls could be reversed on your aileron channel. Check your controls on the ground before flight the next time you're at the field.

2.Adverse yaw which could happen at slower speeds. This happens when you input directional controls only with ailerons. Sometimes you may need to couple your aileron controls with the ruddder.

Hope This helps.

Cheers
RandomTask

i checked all the control. not the control problem

i can agree with u maybe it is the speed.

[flying bear]

It is due to tip stall

hi all,

What Heng Heng encounter is something call the tip stall. Dun think is to do with the reverse of the controls, I am sure Heng have chk it many times.

Chk out the thread below.

http://www.rcgroups.com/forums/showthread.php?t=2505

The GWS guys in taiwan i talk to, did highlight this issue. It is most likely due to the airfoil design of the wing. Some even blame the panel lines for the back aerodynamics. Having said that some suggestions

1) built it light, no excessively big motor with excessively big batts. I seen a good mustang with a gear brushless motor, very light.
2) The beautiful yet exagerated panel line on the wings may need to go.
a) fill them up with micro balloon/pva glue mix, then painted over.
b) Tap over using 2" cellotape both method works well, but putting tape over long wings section withou wrinkles requires a little practice.
3) Batt compartment needs to be mod before assembly to accomodate your batt.
4) bottom section of the nose may be made removable for motor and esc changes..
5) End of it is to fly it fast...!! But landing in fast speed is difficult.

Hope it helps...

I gave up the mustang as it gave me too much trouble...I like the formasa for flying ... but GWS mustang really looks good.

Bear

[Vortices]

hi there....

What you encounter is call aileron reversal. And you are right it is very apparent on GWS mustang and GWS corsair at low speed.

The theory behind it, The down going aileron would normally increase the effective angle of attack producing more lift and the up going aileron reduces the effective angle of attack producing lesser lift, the different in lift between the wings would roll the aircraft in the direction you want to turn.

In aileron reversal, the down going aileron increases the angle of attack so much untill it stalls the wing, this mean as you initialise the roll, the down going aileron would increase the effective angle of attack of the wing thus producing more lift, this would start the roll in the right direction, unfortunately as the aileron continues to be deflected down, it stall the wing produceing zero lift, now the other wing even though producing lesser lift as the aileron is deflected up still produces more lift than the wing that has stall, this would than roll the plane in the opposite direction.This is why during initial roll it seem to go the right direction than suddenly it would roll violently in the opposite direction.

The cure...
1) use aileron differential...means down going aileron has lesser deflection than up going aileron. e.g. up going aileron go 13 degrees up and down going aileron go 7 degrees down. This can be done using programming with 2 servos or mechanically using 1 servo.

2) Aileron up float...adjust both aileron to be deflect 3-4 degrees up at neutral. (stick centre)

3) reduce aileron throw....reduce aileron deflection and couple with rudder to regain roll authority. but this arrangement would restrict slow roll, all roll would look like barrel roll.

Flying bear is right, the big panel lines aggrevates the matter, if you can fill them up or tape over, it would help.

Cheers...try it out and tell how it flew...

[Hengheng88]

hi there....

What you encounter is call aileron reversal. And you are right it is very apparent on GWS mustang and GWS corsair at low speed.

The theory behind it, The down going aileron would normally increase the effective angle of attack producing more lift and the up going aileron reduces the effective angle of attack producing lesser lift, the different in lift between the wings would roll the aircraft in the direction you want to turn.

In aileron reversal, the down going aileron increases the angle of attack so much untill it stalls the wing, this mean as you initialise the roll, the down going aileron would increase the effective angle of attack of the wing thus producing more lift, this would start the roll in the right direction, unfortunately as the aileron continues to be deflected down, it stall the wing produceing zero lift, now the other wing even though producing lesser lift as the aileron is deflected up still produces more lift than the wing that has stall, this would than roll the plane in the opposite direction.This is why during initial roll it seem to go the right direction than suddenly it would roll violently in the opposite direction.

The cure...
1) use aileron differential...means down going aileron has lesser deflection than up going aileron. e.g. up going aileron go 13 degrees up and down going aileron go 7 degrees down. This can be done using programming with 2 servos or mechanically using 1 servo.

2) Aileron up float...adjust both aileron to be deflect 3-4 degrees up at neutral. (stick centre)

3) reduce aileron throw....reduce aileron deflection and couple with rudder to regain roll authority. but this arrangement would restrict slow roll, all roll would look like barrel roll.

Flying bear is right, the big panel lines aggrevates the matter, if you can fill them up or tape over, it would help.

Cheers...try it out and tell how it flew...

Points noted
will try to alter the aileron and try again this weekend.
Thanks

[Hengheng88]

To Flying Bear and Vortices,

i compare other mustang(kyosho) and GWS and i notice tat other aileron is smaller in lenght. GWS aileron occupied almost the whole wing.
i was thinking if i cut my aileron into half will it help?

Hengheng

[Vortices]

unfortunately no, It would make it worse because its shorter so you would need to deflect it more to have same effect. This would in turn induce more apparent reversal.The kyoso and other planes has a different airfoil and cleaner surface, that is why reversal doesnt happen.

Come to think of it Strip aileron is a cure for aileron reversal on conventional aileron set up. So pls dont shorten the ailerons. Try cure no 1. Its the best and most effective.

[Hengheng88]

unfortunately no, It would make it worse because its shorter so you would need to deflect it more to have same effect. This would in turn induce more apparent reversal.The kyoso and other planes has a different airfoil and cleaner surface, that is why reversal doesnt happen.

Come to think of it Strip aileron is a cure for aileron reversal on conventional aileron set up. So pls dont shorten the ailerons. Try cure no 1. Its the best and most effective.

Cure:
1) use aileron differential...means down going aileron has lesser deflection than up going aileron. e.g. up going aileron go 13 degrees up and down going aileron go 7 degrees down. This can be done using programming with 2 servos or mechanically using 1 servo.

Sorry for my ignorant, how do i do differential with 1 or 2 servo?