[MXpilot1]

I recently flew some aerobatics for the first time in my RV6. I would sometimes feel a pulsing in the stick when I held it full over in a primary roll.
Has anyone else experienced this? Does anyone know the cause. I also noticed that the engine would begin to run out of fuel when at the top of a roll. I wouldn't think that it should do this considering the short time spent inverted and the fact that I have a flop tube.

 

[Mel]

The "stick pulsing" is common at about the 240 degree point when you roll a -6 with full aileron. Only 1/2 aileron is needed to roll the -6. As far as the "running out of fuel" at the top of a roll, you don't say whether you are doing a slow roll (where the horizontal axis of the airplane remains on the horizon) or an aileron roll. The flop tube has nothing to do with this because you aren't there long enough for the carb float bowl to run out of fuel. If you are doing a slow roll, this is common. If you will do an aileron roll, it should not happen.
Mel...DAR

 

[penguin]

A Mel said it is a well known characteristic of RVs. I have never seen a good explaination of why it happens. Its been suggested that the airflow is breaking away over the down going aileron. It would be (academically?) interesting if someone were to tuft the ailerons & video during rolls at different speeds.

If you pull any negative g the float in the carb will cut off the fuel supply - just keep some positive on (greater than 0g, not necessarily > 1g) to keep everything running smoothly. If it does quit it will very probably start right up when positive g returns. Fuel injection/pressure carb/ellison tbi are required to keep the engine running inverted.

Pete

 

[dan]

Aileron nose dips out into airstream

The nose of the aileron dips down below the wing and into the airstream -- intended, I believe, to counteract adverse yaw, which it does quite well. With full or near-full aileron deflection, that nose is sticking way out down there. You're feeling the turbulence related to the airflow around the nose. Normal!

)_( Dan
RV-7 N714D (766 hours)
http://www.rvproject.com

 

[sf3543]

This phenomenon was discussed in the RVator a few years back and some one devised small flow diverters made from pieces of PVC pipe that attached to the aileron. (They were flat triangles and attached to the leading edge of the aileron, basically out of sight. The curve of the pipe wall conformed to the curve of the aileron.) Obviously, nothing ever really came of it.
Supposedly, they reduced the buffet on the aileron in a full deflection roll, as you described it.
It was common on my RV6, but by using different techniques in doing your rolls, you can eliminate this buffeting, as someone stated earlier.