HP-24 Project

Update 25 August 2003: Moore vertical!

I'm back from the Standard Class Nationals. As you might already have heard, it was not an extremely well-attended contest; only 12 pilots showed up to vie for the title of Standard Class National Champion. Regardless, it was a very fun contest to work at.

At the contest, I filled about twenty notebook pages with sketches of detail design features from the LS8, ASW-28, and Discus. Mostly stuff like pivots, hinges, drives, and attachments. My favorite thing was the lower rudder hinge on the LS8 fuselage - they mold the hinge attach point into the fender for the pneumatic tailwheel. Even the skid-equipped ships have the internal fender, presumably as a stiffener. Anyhow, that avoids needing a long steel arm to support the bottom of the rudder.

Last week, Steve Smith and I did the fiberglass layups for the second side of the vertical fin. This time, we had a gallon of resin on hand, so no shortfalls.

We had quite a scare after we got the piece in the bag and switched on the vacuum pump. The pump wouldn't start; all that would happen was that the light on the transformer would dim a little. We knew that if we didn't get the piece under vacuum inside about 20 minutes, the resin would start to kick over, and it would be junk. After a few minutes of desparate prying at the fan vanes on the armature, I gave up and started tapping on the cast iron pump housing with a small hammer. Success! The pump started right up, and worked fine through the end of the cure.

The next day, I came back to the part, unveiled it, and sanded the leading edge scarf down. It looks like a good part to me.

The next item of work will be to skin the aft end of the fuselage plug. I'll mount the CNC hotwired cores on the armature tube, and skin them with fiberglass in the same manner as all the other parts.

Going forward, I'm starting to work out some of the wing construction details in my head. One of the things I want to do is to avoid building in some of the surface defects I've observed in some other sailplanes. Specifically, this weekend I looked over a Slignsby Vega that's being auctioned off as salvage. The damage consists of nicks down the leading edge from blowing debris. But separate from that, the entire bottom surface of the wing has tiny pockmarks on a grid spacing of about 1" (or more likely, 25mm). I suspect that the pock marks might show the sites of resin columns in the sandwich foam where ventilation holes were punched in the foam. Whatever they are, I want to avoid them. I'll need to get some good advice on what I can do to avoid stuff like that, not only in the freshly finished articles, but also as they age.

I see that the SG-1 guys in New Zealand are making new progress on their glider. Their Web site shows some interesting new photos on their wing section test coupons:


This coming weekend, I'll be at the SHA Western Workshop in Tehachapi. I've got a half hour talk scheduled; I expect to spend most of it giving an update on project status and answering questions.

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page updated 25 August 2003 all text and graphics copyright (c) 2003 HP Aircraft, LLC