switching to a -8 from a -7

OK, this is a stupid question, and I should have already made up my mind. . .

I have a -7 empennage completed and -7 wings (slow build) to be delivered within the next week.

Does anybody have any options to switch to a -8 at this time in construction?

does the -7 and -8 have the same empennage and wings?

Alton
Wings on the way.

-Vertical stab should be the same except for maybe the fiberglass cap.
-Do you have the larger RV-9 double-flush riveted rudder or the folded, smaller rudder? The smaller folded and bent trailing edge rudder should fit the RV-8 the same if I am correct.
-The horizontal stab width at the fuselage would be wider on the RV-7. I think you're out of luck there.
-The wings, as I understand it, are the same parts. Check with Van's to be absolutely sure. I think the beauty of the CNC computer cut parts is that you don't have to worry as much about a matching fuselage bulkhead as the RV-3, 4 and 6's did. Van is, of course, the one to ask.

Anybody else know different?

Sorry...

The tails are definatly different. I've heard of some putting the -8 tail on the -7, but not the other way around. The wings may be this same. If not they are pretty darn close. Also, it's been a while since I've looked at it, but I think you had to order the fuse w/ the wings or at least specify if you'll be getting the QB or std kit. I *think* they matchdrill (or something) the holes for the spar/carrythrough.

You might call Vans wrt wing interop.

Good choice to switch, though!

The HS is a little differn't since the -7 is wider and has a differn't taper. If you don't trim the rear spars the -7 wings is the same except for the main carry thru spar. The -7 is definatly wider. I belive the spars and center sectios are still match drilled in a jig. So you need to Ask Van's about this. Maybe they can match drill a -8 center using your spars... maybe not. Or since you didn't start building you could swap the -7 spars for-8 spars?

So I'm not the only one!

Alton,

I did the same thing. I started my kit as an RV-7, then went for an RV-8 ride after I finished my empennage. The little voice had always told me to build the 8, but I didn't listen in time. When I called Van's I learned that the 7 and 8 share the same vertical stabilizer, elevators and (at the time) rudder. The rear spar assembly on the horizontal stabilizer is the same, but the gap in the center is wider on the 7 HS to accomodate the wider fuselage. I ended up rebuilding my HS, but saving the rear spar assembly. I got really good at drilling out rivets.

The issue you may have to deal with if you had a newer empennage kit is that the new 7's used the rudder from the RV-9. If that's the case you'll just have to redo the rudder too.

It was a little time consuming, but not too expensive when compared with the total cost of the project.

Good Luck,

RVseventyeight

g'day,
I've just done the first 30hrs on my RV7 come 8 (78)...
Interestingly, I changed as I came across a set of RV8 wings for sale after building my 7 empenage. Like others here, I too was always undecided between the two.
The empenage all fits fine, although the HS does have the wider gap which involves only four different part numbers, being the skins and the two pieces of angle extrusion at the front. I could have made a fairing to cover the gap, but rather than work with fibreglass, I made another (RV8) HS.
I used the bigger RV7/9 rudder. Vans naturally couldn't confirm/deny this would be ok, as it is not tested by them. Fair enough. I can say that after 30hrs I can't see any problems. It doesn't seem too touchy and looks great compared to the short RV8 rudder.
Vans said I could have used the 8 wings to continue my 7 only that the wings were the older variety and things have since changed. That being said, your 7 wings are the only variety now and are the same as the 8 caurrent 8 wings (according to what I was told at the time). Vans says to keep the same spars and centre sections together, but I know (I won't say how) that the spars and centre sections are very accurately done and therefore compatible.
Have fun.
Cheers
VH-DAN