As you can see there is a good 1/4" to 3/8" that the F802C can still go over (Click to enlarge)

What I noticed was that the F802-C (the top plate on the gear tower-see photo) and it’s overlap of the F887 top longeron seem off a tad.  According to Van’s drawings, the overlapping aluminum should pretty much cover the top lonergon up to the F822 side skin.  There is between a 1/4″ to 3/8″ gap (again, see photo).  It is possible for me to “nudge” it over, but only about another 1/8″.  This would give me reasonable edge distance for riveting, but still not cover the top longeron per drawings.

I placed a thred on Van’s Air Force forums and will see what some of the other builders say and post that here.  Feel free to post here as well if you are a builder and have input.

The reason I post this is that the parts are all -1 (pre-punched parts) and it would have been difficult if not impossible for me to have anything mis-aligned due to to my error.

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March 3, 2010 Followup

Here it is after drilling complete with 1/8" gap (Click to enlarge)

I was able to get good alignment with just palm pressure, but went ahead and used ratchet straps just to hold things in place while I drilled.  Ended with 1/8″ gap between  802C and outer edge of  F887 longeron.  Good  enough.  Here is a final photo (left).

This is not my design, but a common approach already completed by many RV-8 builders.  This is just a photo log of my gear tower mod project.

There are many people who have done this many ways.  Special thanks to Axel Alvarez for his template which he kindly mailed to me.  Thanks Alex! If you want to see any photos bigger for detail, just click on the image and it will enlarge significantly (800 x 500 pixels+/-)

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Here is the whole shootin' match, the RV-8 gear tower assembly, cleco'd together before the mod (Click to enlarge)

Essentially this revolves around one of the gear tower pieces, F-802C (in my pre-1 plans) being modified so that you can get inside the gear tower structure to (buck rivets, tighten nuts, fittings) without losing your religion.

Close-up of the offending F-802C (Click to enlarge)

First off, why do it? Well my hands and forearms are just too darn big to do much through those tiny holes, much less, hold a bucking bar or turn a wrench.

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Take a straight edge and draw two lines with a Sharpie (Click to enlarge)

So what’s a guy to do?  Cut out this web of .040 aluminum (the area between the Sharpie lines)

But the question is always, “Won’t that weaken this crucial area?”

Well, I’m just an A&P and not an engineer.  I understand what is going on (stress factors) but have relied on others (an aeronautical engineer/RV-8 builder for example) to run the numbers and show that the mod, may if anything make this area stronger!

Here is what the removed piece amounts to.  Not much!

It aint much! (Click to enlarge)

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Finished cutout (Click to enlarge)

Here is the completed F-802C top plate with cut-out done.(left side only here)

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.040 cover and template (Click to enlarge)

Next you need another piece of .040 2024 to make the cover plate.  Thanks to local RV builder, Mike “Fossil” Ballard, who had two 8 x 12 spare pieces in his shop, I was able to get it done quickly.

Several guys have good info on the Van Airforce site also on this (Mike Stewart, Dan Horton and Alex Alvarez)  They all ran the numbers and I was convinced it was a safe mod.  Mike’s is a little more straightforward, but he hasn’t had any problems with his version.

Alex went so far as to make his template available.  I made my own based on his description and was happy to see his template matched mine.  Nice thing about his was he already had the holes marked, which saved me a few more precious minutes.

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Marking the top plate for drilling (Click to enlarge)

Nuff said.  Don’t wonder or ask what the vise grip is on there for.  I forget.

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Match drilling the two pieces with pilot holes (Click to enlarge)

I positioned the cover plate over the hole in the F-802 piece with the side angles cleco’d on to make sure spacing didn’t get off (look at the back side of the F-802C). I then drilled the top (of radius) holes on each end, cleco’d those then drilled the rest all with #40 drill for pilot holes.

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Top plate with pilots for #19 holes (later) and additional holes for nut plates. (Click to enlarge)

Next I removed the top plate after match drilling, and marked and drilled for the K-1100 nut plates.

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Nut plates installed. Squeezer is great here! (Click to enlarge)

I went ahead and drilled all the holes for screws the correct sizes (#19 for the screws and others already done with #40 for nutplate rivets)

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Dimpled both pieces with dimple dies. (Click to enlarge)

I guess you could mechanically countersink these, but being where it is, I (personal preference) didn’t want to removed any more material.  So I dimpled these.

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Here it is temporarily cleco'd in for reference & scale (Click to enlarge)

In the end, there are several ways to skin this cat.  Of course, many people have built their 8’s without this mod and that’s fine.

But as for me and my hands….I’m pleased with the result.