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How much shimming is required

P

PH-SCP

Well Known Member
Hi RV'tors,

When I am in level flight, 2 persons on board and normal weights, fully trimmed out, my elevator is down by a few degrees, exposing the counterweight area by about 3/4 inch (2 cm).
With the elevator slightly down and the counterweight area up, I am sure that I am losing speed since they act as speedbrakes.

I need to put shims under the horizontal stabilzer but I'm not sure how much.
Can anyone advise me what kind of shimming is required to "work away" about 3/4 inch exposed elevator ?




 
PH-SCP said:
Hi RV'tors,

When I am in level flight, 2 persons on board and normal weights, fully trimmed out, my elevator is down by a few degrees, exposing the counterweight area by about 3/4 inch (2 cm).
With the elevator slightly down and the counterweight area up, I am sure that I am losing speed since they act as speedbrakes.

I need to put shims under the horizontal stabilzer but I'm not sure how much.
Can anyone advise me what kind of shimming is required to "work away" about 3/4 inch exposed elevator ?
Click to expand...

Confirm that you did install the 1/8" shims under the holddown points for the horizontal stab as shown in the plans first. In the instructions there is also a procedure to verify the angle of incidence of the horizontal stab.
 
scard said:
Confirm that you did install the 1/8" shims under the holddown points for the horizontal stab as shown in the plans first. In the instructions there is also a procedure to verify the angle of incidence of the horizontal stab.
Click to expand...

I have to check, I bought the plane from a guy in Florida.
Thanks for pointing it out.
 
I believe that it is designed to be postioned like this in flight. This was told to me by Bill B when he looked at my six in flight in 1995. I would talk to Vans before screwing with it. Larry
 
Hi Simon,

As Scott said, first confirm that there is the 1/8th inch shim under the front attach points on the HS. If yes, then you will need to check the back of the construction manual for corrective procedures--I believe it was in the flight testing section in my 2003 vintage manual. Having 3/4ths of an inch of the elevator counterwt showing above the HS under normal cross country wt/cg indicates that excess down force is built into the HS. Correction is made by adding shims to the front attach point.

I had about 7/16ths of an inch of the elevator counterwt showing above the HS in my normal x cntry configuration (cg/power setting/speed) and it took (speaking from memory here) something more than an additional 1/16th of an inch under the front attach points to correct.

I talked with Ken K. at Vans about this prior to taking the action and was told not to expect much if any change in speed--and he was right. If there was an increase in speed it was less than 1 kt AND remember that you will have to rework the HS to VS fairing after the change.

If you need more details I can find the exact shim size in my records next time I am at the airport--PM me if necessary.

Cheers,

db
 
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