Constant speed VS. fixed pitch

[MauiLvrs]

We based the 20 on the way the plane feels, and what others seem to do.
For normal take-off we use no flaps. The 20 deg. that we use are for short field. 30 deg. felt like it was too much. The gain from 10 deg. didn't seem to be as much as 20 deg. I believe that the number may be between 15-20 deg. as that is what we have experienced. Probably doesn't much matter unless you're flying of a strip 1000' or less. With me and 20 deg flaps on a cool morning, it wouldn't be difficult to clear a 600' obstical at the end of our 4000' runway.

It would be difficult without a wind tunnel to get exact data for the wing/flap configuration. One thing that we have learned is that consistent data is difficult to obtain. Another is that it takes much effort to extract useful data from a dump of the data logger. It samples 1/sec, but extracting say useful CHT data from that is difficult during climb as many of the parameters are changing.

Hey Dave,
as a -9a driver with little time on type, I am trying to assemble the correct operational data.

why 20 degrees of flap for takeoff? Have you tested this as the best lift for the wing?

 

[penguin]

I have a 160hp 6A (in fact a 150 with new cylinders to bring it up to 160 & no weight increase) with a 80" pitch Sensenich FP - that was what was fitted when I bought the airplane, I upped the pitch to 80" for 77" when I fitted the 160hp cylinders. I regularly fly from a 1800' grass strip at max weight, initial acceleration is not great, but its acceptable. Cruise performance is excellent, I have flown 1100nm in a day on several occasions. I can over-rev the prop at low level. Solo I can land with a ground roll of around 500' on wet grass. A couple of times I have had exciting take-offs when flying from short strips with trees at the end, but I would definitely go back into both.

I regularly fly aerobatics and would consider flying in competitions at Sportsman (if I didn't also have a share in a One Design). I also regularly fly formation. OK, formation take-offs with a 180 c/s leader has him way back on the power, but after that its not an issue. I fly formation aerobatics with fp and c/s leaders - the only limitation is my skill at staying in position, the prop is not a factor.

I do throttle back in rain, but only because I don't want to lose the paint from the leading edge.

Having said all of that I will be fitting a c/s prop (probably an MT) to the RV-7 I am building, if I can at all afford it. Its just makes the airplane so much more.

Pete