Where does the trailing edge attach to rib O on the Chrysalis?

The instructions on the Chrysalis need a clarification on them. When glueing the wing tip balsa to rib O, does the TE of the tip balsa attach to the TE piece flush with the bottom, or somewhere in the middle? I glued it flush with the bottom and didn't think about it again until after I attached the LE. After I took it off of the building board, it occured to me that it didn't look right and I should have glued it flat onto the bottom spar cap and to the TE stock shimmed up a bit (1/32 or maybe 1/16). The instructions say only to glue it in place, but not specifically where.

I'll build the other one the same way (symmetry is a good thing), but I think the effect of this is to raise the philips entry at the tip. This will change the airfoil at the tip and the effective angle of attack will increase. That means washin and may cause tip stall problems.

Lex, I understand your concern, but don't worry, you did it correctly, and no, it doesn't create washin in the tip, nor does it cause any tip stall problems. All the ones I've built had the tips done this same way, and they flew just fine.

Forget "Phillips entry", what matters here is the local chord line. When you build the tip by this method, the chord line of the tip is a very close match with the chord line of the tip rib. There is essentially no incidence difference between the tip and the "O" rib. In addition, the critical region for "tip stall" isn't really so much that area of the wingtip; the area about one to three chord lengths inboard of the tip is actually much more critical. At the very tip the lift is zero, and attempts to generate lift there will be utterly futile. The more pressure differential you try to generate there, the faster the air will spill around the tip, spoiling your efforts. Even with a constant chord (or "Hershey bar") wing, this is still true.

By the time you get about one chord length inboard, there is enough wing outboard of that point to support some pressure differential, and therefore some lift coefficient. At that point you can start worrying about "tip stall". In the Chrysalis wing, this area is well inboard of the tip plate.

Don't worry, you built it just like the plans show. They don't say anything about shimming up the trailing edge of the tip plate, simply because no shim is needed! Your Chrysalis should fly just fine.

One more question. At the trailing edge, the ribs are not as high as the TE stock. I built it with the ribs flush with the bottom. Should I get the sanding bar & take down the TE stock to the same height as the ribs, or should I just leave it alone?

What you're seeing is manufacturing tolerances in the T.E. stock. They're supposed to match, I spent a lot of time on the CAD files for the ribs making sure they would match, but we're still at the mercy of the variations in the balsa stock. Unfortunately, table saws aren't as accurate as lasers, and also not all pieces of balsa cut the same, even with the same settings on the saw.

If it's close (and it should be), I'd say it's optional. Just make sure the T.E. is smooth, and let the covering fair across it. It might be a little better to sand everything to match perfectly, but there is a very real risk of damaging the ribs in the process, which would then be worse. Use your judgement, make it look nice, but don't take any unnecessary risks.

(do you guys spend, like 90% of you time answering emails??? :-)

Some days it seems like that. I really don't see it as a problem, though. It does take away from time we could spend developing new kits, but it also provides much of the feedback we need to understand the point of view of our customers, and to find ways to improve our products. I see it as a very worthwhile investment.

Don Stackhouse @ DJ Aerotech