Tom Martin
Well Known Member
I have the cowlings off now and I set the top one in place to take this picture. Note that when normally attached there is a small 1/8"? gap between the foam seal and the prop hub.
My intent to seal around the prop shaft was for drag reduction, not cooling. However as I noted before I was not able to demonstrate an increase in speed but I could see an effect on cooling. I have made many changes to this plane over the last few years and have demonstrated a 10 knot increase in speed, this can be verified by SARL participation. The only change that I could really verify, by itself, was the change from an MT prop to a BA Hartzell. All the other changes, this one included, collectively added up but were too small to individually note. However, improving the cooling allowed me to tighten up my exit air which may have helped to improve speed. Cooling system changes are like pieces of a puzzle in that they all have to work together.
My intent to seal around the prop shaft was for drag reduction, not cooling. However as I noted before I was not able to demonstrate an increase in speed but I could see an effect on cooling. I have made many changes to this plane over the last few years and have demonstrated a 10 knot increase in speed, this can be verified by SARL participation. The only change that I could really verify, by itself, was the change from an MT prop to a BA Hartzell. All the other changes, this one included, collectively added up but were too small to individually note. However, improving the cooling allowed me to tighten up my exit air which may have helped to improve speed. Cooling system changes are like pieces of a puzzle in that they all have to work together.