Originally Posted by egp8111
I have an early set that shows a different horizontal stab. attach method (# 30)
if thats what you need. I contacted Van's and they said either one was OK. There is a picture of it on the forum you can find if you search "stab attach" or such. PM me if you can't find it and I'll send you a pic of my old plans sheet
Turns out I now have a couple of version of older plans.
I've been assisting on a condition check on an early RV-4. When we first saw it we were concerned that the original builder had invented his own horizontal stab attach- partially the result of being a little hair-trigger due to all the RVs that have come through the shop with atrociously poor stab attach workmanship. A call to Van's didn't help- apparently no one on current staff was aware of the significant changes that Van made on the horizontal stab attach as the RV-4 evolved, and photos led them to conclude erroneously that it was not to (early in this case) plans. Where is Van when you need him?
Now we realize that what we were looking at was actually a properly executed example of rev 1-ish tail tail attach. The F-410 bulkhead is one piece but the attach angle is behind the horizontal stab spar, not in front of it as in rev 0. My guess is that the RV-4 horizontal stab attach, with its associated split F-410 bulkhead layout that has become the standard layout for Van's tail attach was done because the original RV-4 attach was really difficult to install. Thinking a midget with Gumby arms would've been necessary to get on the bolts that would only have been accessible by shimmying into the aft fuselage head-first.
It's been fun gaining a little insight into the evolution of Van's designs in the last few days. Thanks again to all that replied and supplied me with most useful information!