Scott Hersha
Well Known Member
I have a question for those familiar with changing the horizontal stabilizer angle of incidence on RV's - and RV4's particularly. I believe the angle of incidence isn't set correctly on my RV4. I'm the third owner of this airplane, and it's been flying for 16 years, so maybe I should just leave it alone, but if it can be changed to improve its aerodynamics a little, I might pick up a little speed. Here's what I have: In straight and level trimmed flight at cruise speed (~155K) my elevator is slightly deflected trailing edge down about 2 degrees (nose down pitch trim)to maintain level flight. My CG in this condition is pretty close to the middle of the CG range. The leading edge of my elevator counterweight horn is about 1/2" above the leading edge of the HS. If I streamline the elevator to make it even with the HS, I'm climbing at 1000 fpm. It seems to me that to correct this, I should raise the leading edge of the HS up a little with washers, or spacer under the HS front spar where the 4 bolts are connected to the aft fuselage plate and longerons. The plans call for two 1/8" spacers to be used here, however, the builder of this RV4 used 1/4" spacers, so it's already higher than plans call for. I'm thinking I need to move it up even more to fly with a streamlined elevator.
I don't want to create a problem with stability or structural integrity, and I want to make sure I move it in the proper direction. I'll have to guess at how much. It's not easy to do this. I'll either have to remove my elevator push-pull tube in the tail and squeeze my not so limber body into the tail cone to get to the nuts on those bolts - or, remove my rudder and VS to allow access to the bolts/nuts through the small lightening hole in the aft turtledeck bulkhead. Either way, I'll have to re-align my rudder because the top of the VS will be slightly further aft. And what does this do to the aft spar of the VS that bolts firmly to the aft fuselage bulkhead, but now slightly 'tilted' from where it used to be? .........sounds like I've almost talked myself out of doing anything....... If anyone has experience in doing something like this, or recommendations, please let me know.
Thanks
I don't want to create a problem with stability or structural integrity, and I want to make sure I move it in the proper direction. I'll have to guess at how much. It's not easy to do this. I'll either have to remove my elevator push-pull tube in the tail and squeeze my not so limber body into the tail cone to get to the nuts on those bolts - or, remove my rudder and VS to allow access to the bolts/nuts through the small lightening hole in the aft turtledeck bulkhead. Either way, I'll have to re-align my rudder because the top of the VS will be slightly further aft. And what does this do to the aft spar of the VS that bolts firmly to the aft fuselage bulkhead, but now slightly 'tilted' from where it used to be? .........sounds like I've almost talked myself out of doing anything....... If anyone has experience in doing something like this, or recommendations, please let me know.
Thanks