Yaw Curiosity

[Bob Axsom]

I took this photo as one of many during experimenting with a modification to the cooling air outlet. I fly with the ball centered although if it is out it is a fraction of the ball to the left. The separation in the exhaust pattern on the belly in the photo I believe is caused by the ~2ft long central fin in the extended cooling air outlet. I observed that it angles off to the right instead of continuing straight down the approximent center of the fuselage. The only logical explanation I can come up with is the plane is flying with the nose yawed to the right most of the time. Does this say anything about the alignment of the turn coordinator with the axes of the airplane. How much speed is lost flying sideways like this?

Bob Axsom

[billnaz]

The elusive spiraling slipstream?

[Bob Axsom]

It seems like that would displace it the other way with the prop rotation.

When I put the mounts on the fuselage I dropped plumb lines from the firewall center and the center of the tail end of the fuselage to align the "center" fin with the fuselage centerline but the center fin if NOT in the center of the fuselage. It is offset to align with the cowl support structure on the "A" model which is 6+ inches from one side of the outlet and 7+ inches from the other side but it is parallel with the fuselage centerline as close as I could get it.

Bob Axsom

[frazitl]

in a slip, imagine what your speed would be without the yaw! Might just be a photographic phenomenon. Try taping a piece of yarn to your windscreen directly in front of you for your next flight like the gliders do. I don't know what to expect, spiraling slipstream indicator or useful yaw indication???

Thanks for adding to the Writ of Common Wisdom that is (most of) VAF!

[bpattonsoa]

The glider yaw string is great on gliders. I often hate mine! Forget it on a RV windsheild.

Best bet is to fly using a good gps speed, groundspeed or otherwise, and then lightly push on the rudder until you get some "yaw". Give it a minute and check speed. Do it with more push, check, try the other side. An autopilot will help, but is not required.

Everyone should try it.