Lowering Aileron Effect / Performance at slower speeds?

#1
Hey all,

Was having someone test my plane and he noticed my ailerons didnt lose their performance at landing speeds. And so I thought.. Perhaps there is a table I could adjust in the AIR file. I found the CIp table in section 455, which is equal to the setting name in the Roll section for ailerons in Section 1101.

I experimented with (shooting in the dark) with lowering settings on the left side of the table graph to see what effect it would have. It was messy. So I thought, I should ask the big guys on this one.

10,000 dollar question; Any way to adjust (lower) performance of the ailerons at slow speeds? This is the Extra 300 flight dynamics files from FSX. Not the P3D version.
 
#3
The Extra is an intense airfile set, extreme aerobatics. I need it for flat turns. But wondered... can I effect performance per speed on ailerons or other systems for that matter? Would be interesting to know if I could.
 
#5
The Extra is an intense airfile set, extreme aerobatics. I need it for flat turns. But wondered... can I effect performance per speed on ailerons or other systems for that matter? Would be interesting to know if I could.
Sure. 1535 limits the effectiveness due to AoA and 518 limits the deflection angle due to dynamic pressure (speed)
Changing the aileron effectiveness changes the effectiveness over the whole speed/AoA range.
 

Roy Holmes

Resource contributor
#7
The stock Extra roll rate peaks at 320 degrees per second at 166 knots. Roll rate increases linearly with speed up to that point. So it would be 80 degrees per second at around 40 knots which is slightly below landing speed.
If you halved the full aileron effectiveness in Record 342, it would still be way more than most airplanes.
So you cannot bias the roll rate to be proportionally less at slow speeds. It is what you get.

You can reduce the roll rate at higher AOA using 1535 as Bernt mentioned. If you wanted to you could reduce it to zero at landing AOA. Currently it is full effective up to 10 AOA which is about landing AOA
You can reduce roll rate using 518 which simulates control deflection reduction at high speeds (actually dynamic pressure) Currently the Extra has reduction in roll rate starting above 166 kts and reducing to about 1/4 of that at about 250 kts

You can reduce the aileron deflection limit in the aircraft.cfg, which has a similar effect to reducing effectiveness and this would reduce roll rate at all speeds.

While aileron effectiveness is less at landing speeds than at higher speeds, I doubt you would see a noticeable reduction of effectiveness with the Extra because it is so high in general.

However, since you want to do flat turns without aileron induced roll, why not simply reduce the max deflection in the aircraft.cfg to something like 5 degrees.
Roy
 
#8
1538 would be better. A light airplane like that will "kite" as the nose goes up. That's the reason it loses roll performance. The increased pressure under the wings wants to be equalled. There should be no physical change to the ailerons themselves, I don't imagine that design being tab driven. You should still have full performance at slow speed with an unloaded wing!!! And acrobatics will unload a wing way more often than any normal flight.
 
#10
Many thanks guys. Very much appreciate it.

That reduction in deflection is an interesting idea, Roy. That would help the flat turns. The big wingtip ailerons do not hinge that much. They are a large amount of area, but low angle of deflection.
 
#11
You can reduce the aileron deflection limit in the aircraft.cfg, which has a similar effect to reducing effectiveness and this would reduce roll rate at all speeds.

Roy
I just tried it out... Backwards effect. You have little input required for 'correction' with 30 degrees aileron deflection. With 5 degrees, you need nearly full aileron input to do your flat turns. Not good. But... I did reduce it to 20 degrees and the input was still a fairly low amount needed to do flat turns, so that did well. Before, its like an F-16 fighter jet with minimal armament. Spins like a dart! (Love that... )

I have fallen in love (a little bit.. well.. a lot) with the Extra 300 flight dynamics. I have added it to my Bullet plane. Doing a few adjustments to bring it into that planes settings. Very interesting dynamics compared with all the other aircraft.

Very odd wings. I noted that the wings 'top surfaces' are flat on the 300 Extra. Crazy...


Bill
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#12
What is 'odd' to me is that the 300 slows down so fast when you throttle back to idle. Deceleration is moderate. You would think such a sleek plane would have 'slow down' issues, like a Lear coming in on Approach. But no... Its like she is a tri plane with a bunch of area and wires going on.
 
#13
Very odd wings. I noted that the wings 'top surfaces' are flat on the 300 Extra. Crazy...
It's a symmetrical airfoil, the lower section is flat as well. When Walter Extra used this airfoil quite a few 'experts' claimed the plane couldn't and wouldn't fly…..
Concerning drag; Look at the thickness of the wing and the nose radius, lots of drag (needed for vertical maneuvers when pointing straight down)
 

Roy Holmes

Resource contributor
#14
Bill,
The reason it slows down is the propellor creates drag when you throttle back and the Lear only loses thrust nothing else.
One of the most obvious differences when converting to jets after flying props is that the thing hardly slows at all when the throttle is closed, hence the need for speed brakes.
Compared to prop drag the airplane parasitic drag is small.
Roy
 
#15
Nevertheless the Extra 200/300 design does create a lot of drag, even for a prop driven aircraft. A typical Cessna with its strutted high wing and its tricycle gear has an L/D ratio of around 9, while the Extra has a L/D ratio of only 6.
 

Roy Holmes

Resource contributor
#16
And the Cessna wing loading is 14.1 lbs/sq ft while Extra is 20.5. About the same ratio as L/D. The Extra has a symmetrical wing section which has less CL than the 172 wing plus the extra wing area is 102 feet compared to the Cessna 174. The wing may be draggy but the L/D difference comes from less lift as well as possibly more drag.
Roy
 
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