Van's Air Force
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aileron snatch
- Thread starter Garybrown
- Start date
more info
model, engine, weight, mods?
Aileron snatch "usually" means your aileron trailing edges are too rounded, from what I hear. They act as little airfoils to accelerate the aileron in the direction of movement.
If your trailing edges are bent, not riveted, you could try decreasing the radius a bit.
Just a WAG, take it for what it's worth.
model, engine, weight, mods?
Aileron snatch "usually" means your aileron trailing edges are too rounded, from what I hear. They act as little airfoils to accelerate the aileron in the direction of movement.
If your trailing edges are bent, not riveted, you could try decreasing the radius a bit.
Just a WAG, take it for what it's worth.
Norman CYYJ
Well Known Member
all RV's will exhibit some at full deflection.
Kevin Horton
Well Known Member
Please describe exactly what happens. Aileron snatch is condition where if you put some aileron input in, and release the stick, the stick will go to full aileron deflection and stay there unless you pull it back to centre. Is this really what you mean, or are do you have another problem?
the ailerons move just a bit in rough air, the stick will deflect about an inch in either direction, I can slap the stick, it will react then center, it is just a bother that in rough air the stick wants to move in my hand slightly. I will try pinching the trailing edges a bit, any other ideas? thanks, Gary
Van's has addressed this problem in an old issue of the RVator and I believe it was due to the trailing edges of the aileron's being squeesed down to too small a radius. The fix as I recall was to hold a block of wood along the trailing edge and tap it with a hammer. Sounds terrible, but I've come to trust Van's advise. You might try contacting them dirrectly.
Dave Cole
Well Known Member
Don't over do it
I don't think you want to create a squared-off trailing edge...forming a square corner in sheet metal is an invitation to cracking.
I would expect that the "tap it with a hammer" instruction is intended only to open up the trailing edge radius a bit.
I don't think you want to create a squared-off trailing edge...forming a square corner in sheet metal is an invitation to cracking.
I would expect that the "tap it with a hammer" instruction is intended only to open up the trailing edge radius a bit.
Kevin Horton
Well Known Member
Have you flown in other RVs in similar conditions, and if so, how did they compare to yours? How much friction is there in the aileron controls of your RV, as compared to others?
It is hard to know for sure, without knowing what the conditions were like, but what you describe could possibly be completely normal. A well built RV has very little friction in the aileron system. The stick will move to the position that equalizes the forces in the whole system. If both wings have the same angle of attack (as they do most of the time), the natural lateral position of the stick is in the middle. But, if you hit a bump, and this bump affects one wing more than the other, there will be a very short period where the two wings have different angles of attack. Thus the air pressures on the top and bottom of the two ailerons will differ, and it is quite possible that this would result in the stick moving laterally to balance out all the forces in the aileron system.
For example, imagine that you hit a bump that increased the angle of attack of the right wing. This would increase its lift, causing the aircraft to roll to the left. The increased angle of attack on the right wing would increase the pressure on the lower surface, and decrease the pressure on the upper surface. This changed pressure distribution on the right wing would tend to push the trailing edge of the right aileron upwards a bit, I think, which would cause the stick to move towards the right. Maybe.
