RV-8 wing spars

Hiya We have done the search for info on the different types of wing spars for the RV8 series aircraft, we are looking at a project for sale. What we have learned is that the RV 7 spar parts are also used for the RV8 although the mounting holes are different and won"t interchange. Our question is about the early kits prior to the introduction of the RV7. The large aluminum bars that are machined are smaller on this kit than the later ones ? Is there less strength because of that even though the numbers quoted are the same as later kits for G rating ? Caitlin and friends

As far as I know the only thing that changed with the new beefed up spars was an increase in max. aero. weight from 1550# to 1600#, but I'm not positive.

Thanks briand any information we get is helpful Caitlin

caitlinRV said:

Hiya We have done the search for info on the different types of wing spars for the RV8 series aircraft, we are looking at a project for sale. What we have learned is that the RV 7 spar parts are also used for the RV8 although the mounting holes are different and won"t interchange. Our question is about the early kits prior to the introduction of the RV7. The large aluminum bars that are machined are smaller on this kit than the later ones ? Is there less strength because of that even though the numbers quoted are the same as later kits for G rating ? Caitlin and friends

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Caitlin,
The newer Mark I style wing main spars on the 8 & 8A are similar to the RV7 units. These differ from the older, original design in several ways. The lower spar cap (big square bar stock) extends out one rib bay farther than the original items. My old style spar caps both end at the intersection of the fuel tank to leading edge. On the newer units, the lower cap extends to just short of the 2nd (from inboard) leading edge rib. The newer spar cap is also slightly (I think about .25") thicker. The milled "steps" on the cap are more numerous, due to the added thickness.
Vans tested the original spar design after the crash of it's demonstrator plane, N58RV. The tests were conducted on an owner built wing, rather than a wing built by Vans. An outside engineer was brought in to conduct the testing. Bottom line was that the wing exceeded 9Gs positive without failing. (The top skins started to wrinkle at this point)
The big advantage of the new design is that it moves one of the stress points away from a "stack" of stress points in the original design. The original lower spar cap ended at the same station as the seam between the fuel tank and leading edge. The middle inspection cover and the large pitot tube hole in the spar flange are also in this same general area. On the original design you had 4 stress points all in close proximity.
If you purchase an older style wing kit, I suggest that you not locate the pitot tube where the plans call out. Either move it outboard, or better yet, install a Piper "blade" style pitot tube. These units work best when installed 8" aft of the spar. Use of the blade style unit eliminates drilling a large hole anywhere in the lower spar flange. This is what I did. I also fabricated slightly wider W-423 LE to fuel tank doublers. I added a 2nd row of rivets to the leading edge side of this doubler to add a bit of strength here. Generally accepted practice is to secure doublers with two rather than one row of rivets. I hope this helps.
Charlie Kuss
RV-8A cockpit wiring

Hiya chaskuss Thanks , this all helps in making our decision on whether we buy an early kit with some work done or go with a new purchase. Caitlin