[PaulR]

I'm getting ready for my plane to go to paint and have been perusing "speed-mods" before taking it. I ran across a thread that Bob Axsom posted about closing in the ends of the horizontal stab. and the elevators in which he said gained him 3 knots on his 6.

I'm wondering if the consensus was that it would increase the speed by a like amount on a 9A?

Also, if the consensus is it will, is there a "best" way to do it? I'm thinking about nut-plates on the ribs and installing a piece of balsa wood with screws, then covering it all with a layer or two of f/g cloth and filling with micro and sanding.

Seems like the glass cloth would keep the screws from ever becoming a hazard to locking the controls.

Thoughts?

 

[Rupester]

Since the dimensions of the HS on a 9A are completely different than the HS on a 6 or 7, it's hard to say what the gain might be. Given the elevator is barely deflected in cruise, I (personally) doubt if there would be that much of a gain. But there must be somebody out there in a 9 that did it and measured it.

 

[PaulR]

Terry,
Do you believe the gains Bob got were all because of deflection? At cruise mine are deflected about 1/4 to 3/8 depending on loading. I sent him a PM but I haven't heard from him. I bet he's getting ready for race season.

I was assuming that at least part of it had to do with the air coming in the gap between them and swirling. I'm no engineer, obviously, but it seems to me to make sense if the ends were smooth rather than "dished" inward it would be better.

I'm hoping someone else with a 9 has tried it and measured the difference and is willing to chime in. It certainly looks better, to me, and not as inviting to the "mud daubers" down in here Lower Alabama.