whifof100ll
Well Known Member
Hello Fellow RV Enthusiasts,
I am the second builder of my non-pre punch RV-6. The first builder did a pretty good job on many things, but there are some boo boos that I have been fixing (all well worth it).
I have recently mounted up the tail feathers to check rigging. With the horns bolted together and left elevator clamped to the HS in area of the counterweight, I noticed that the elevator counterweight on the right side is 1/4 inch low (front edge sticking out in the breeze). I then put a 4' level across a 1/8" spacer at the front HS spar and a 1/4" spacer at the rear HS spar projecting it back over the elevator trailing edge. I measured down to the elevator trailing edge center with a metal rule at different locations on each side comparing like right/left locations.
I did not know what was bent, but knew something was bent, to I took everything apart and layed each piece on a granite table.
I have learned the following.
HS and left elevator are perfectly straight. The right elevator spar is straight, but the elevator was built with about a 1/2" twist at the trailing edge (skin drilled and riveted on crooked.) :<(
With the horns bolted up, the trialing edges of the right and left elevator are even at the metacenter of the elevators (mid point in terms of flying area of each elevator). I therefore think that each elevators as rigged would not produce any real rolling moment, but perhaps some extra drag due to a small rolling moment localized to the right elevator only.
I first thought of re-building just the right elevator. Then since I have 016 skins, I was sort of inclined to buy all new pre-punch 020 elevator parts and built two new ones. ($400). I know 016 skins crack, but do they always crack?
I have spoken to two people about this and both advise against building new elevator(s). They say no big deal, just get the plane flying. Fix it after the plane flies if you want.
Van's tech support advises to weld up one elevator horn, clamp both elevator counterweights to the HS, re-drill the welded up horns. I think this is an easy thing to do, but I believe it would give me a much larger rolling moment than I am likely to have now. He says most RV-s are bent that much.
Another friend who is an experienced builder says not to re-drill the horns but to remove the counterbalance skin (E613), cut bend, and mend the end rib (E603), re-rivet it all together. This would leave the trailing edge twist, but the metacenters are lined up right to left, and it would streamline the counterbalance weights behind the HS right to left at the same stick position. I worry about how well the fiberglass tip will fit.
I also considered drilling the skin off the spar, going with an NAS repair rivet, and trying to rivet it back together straight. Since this is a dimpled skin, nobody, (including me) really thinks this is a good solution.
Does anyone think a 1/2 in twist in the trailing edge of one elevator creates enogh drag to cause a performance difference? I don't need to have the fastest RV made, but I want to cruise at 190MPH.
Also, Have any of you filled fiberglass holes with fiberglass filler and re-drilled? I think i may need new holes and winder about filling vs buying new parts.
How compelled should I be at replacing skins because mine are 016?
Thanks in advance for answers to these questions or other advice you may have,
Dale
I am the second builder of my non-pre punch RV-6. The first builder did a pretty good job on many things, but there are some boo boos that I have been fixing (all well worth it).
I have recently mounted up the tail feathers to check rigging. With the horns bolted together and left elevator clamped to the HS in area of the counterweight, I noticed that the elevator counterweight on the right side is 1/4 inch low (front edge sticking out in the breeze). I then put a 4' level across a 1/8" spacer at the front HS spar and a 1/4" spacer at the rear HS spar projecting it back over the elevator trailing edge. I measured down to the elevator trailing edge center with a metal rule at different locations on each side comparing like right/left locations.
I did not know what was bent, but knew something was bent, to I took everything apart and layed each piece on a granite table.
I have learned the following.
HS and left elevator are perfectly straight. The right elevator spar is straight, but the elevator was built with about a 1/2" twist at the trailing edge (skin drilled and riveted on crooked.) :<(
With the horns bolted up, the trialing edges of the right and left elevator are even at the metacenter of the elevators (mid point in terms of flying area of each elevator). I therefore think that each elevators as rigged would not produce any real rolling moment, but perhaps some extra drag due to a small rolling moment localized to the right elevator only.
I first thought of re-building just the right elevator. Then since I have 016 skins, I was sort of inclined to buy all new pre-punch 020 elevator parts and built two new ones. ($400). I know 016 skins crack, but do they always crack?
I have spoken to two people about this and both advise against building new elevator(s). They say no big deal, just get the plane flying. Fix it after the plane flies if you want.
Van's tech support advises to weld up one elevator horn, clamp both elevator counterweights to the HS, re-drill the welded up horns. I think this is an easy thing to do, but I believe it would give me a much larger rolling moment than I am likely to have now. He says most RV-s are bent that much.
Another friend who is an experienced builder says not to re-drill the horns but to remove the counterbalance skin (E613), cut bend, and mend the end rib (E603), re-rivet it all together. This would leave the trailing edge twist, but the metacenters are lined up right to left, and it would streamline the counterbalance weights behind the HS right to left at the same stick position. I worry about how well the fiberglass tip will fit.
I also considered drilling the skin off the spar, going with an NAS repair rivet, and trying to rivet it back together straight. Since this is a dimpled skin, nobody, (including me) really thinks this is a good solution.
Does anyone think a 1/2 in twist in the trailing edge of one elevator creates enogh drag to cause a performance difference? I don't need to have the fastest RV made, but I want to cruise at 190MPH.
Also, Have any of you filled fiberglass holes with fiberglass filler and re-drilled? I think i may need new holes and winder about filling vs buying new parts.
How compelled should I be at replacing skins because mine are 016?
Thanks in advance for answers to these questions or other advice you may have,
Dale
