HP-24 Project

Update 21 May 2007: It all adds up

Over the last couple weeks I did the second of two one-hour intro to aeronautics courese for the Gate program, got in a bit of climbing, and did some good work up at the shop.

For the second GATE session, I had a better grasp of the timing, and I think the whole thing went a lot better. This time we spent more time running the wind tunnel with my test airfoil, answering questions like, how do wings work upside down? How do race car wings work? We also spent more time with the Break-O-Tron. In addition to pull-testing the 7075-T6 coupon and shearing the pair of MS20470AD4-5 rivets, we also broke a cheapie "Not for Climbing" carabiner that was stamped with a 100 lb safe working load. That little toy was the hit of the show. I expected it to give up around 400 lbs, and when it went through 1000 lbs I backed the kids up to the limit of my hydraulic hose. It finally gave at 1200 lbs, failing at the hook that captures the gate latch pin.

I took the Friday after the GATE session off and drove down to Yosemite to get in some climbing. That was a nice trip and a nice visit, but somewhat of a bust as climbing goes. I went straight into the park to the launch chimmey of the Royal Arches Regular route to see if anybody would tow me up as a third. Nothing doing. Then I went to After Six, and had the same experience. Then I retreated to Swan Slab and toproped a bunch of the standards, but there were a lot fewer climbers than I expected.

That weekend we got a lot of stuff done at the shop, but most of it was for finishing out the fitting of the ASK21 to its Komet trailer. The big project was welding up a couple of wing root dollies. The dollies that came with the trailer cradled the leading edge of the GROB wing. Unfortunately, the wing root profile is very different from that of the ASK, so we could not use them. Instead I welded up dollies that will support the wing spar stub at its forward face, and index with a padded spindle that inserts into the wing pin hole. I pretty much welded them up by eye, copying the chassis of the original dollies and locating the platform using a cardboard template of the wing side-of-body profile.

I also started welded together six ASK21 disassembly tools, incorporationg several design changes based on beta testing. This second round of tools will have rotating elements that reduce wear on the drag pin locking bar and the tailplane locking wire.

This last weekend I did more work on the upper hinge radius of the right wing flaperons. Basically I cut radius blanks from a sheet of 3/4" MDF, temporarily attached them to the flaperon plugs using hot glue and popsicle sticks, and then bonded them more permanently using epoxy and microballoons. Now they're almost ready to go to Radius Maximus to get shaped.

I also replaced the back tire and tube on Raen's bicycle. She is fond of skidding to a stop, and has already worn through the tire.

Friday, 11 May at the awkward start of the Royal Arches regular route. This is two a party of three Brits visiting the US. The leader actually did this facing the other way round, the first time I'd ever seen that pulled off.

Half Dome as I was leaving the park. I've never really done landscape photography; I always figure to just buy the postcards. I also noticed that when we came across my mother's photo albums we skipped right over the photos of places and studied those of people and things. But HD was so pretty, and I thought it'd be fun to get a photo of a photographer getting one of those artsy landscape pics.

The two ASK21 wing root dollies. Yes, we intended to make them different heights; the short one on the right fits the forked spar butt.

Forward to 19 May, this is the stack of 4-foot strips of MDF for the flaperon plug radius blanks.

Raen's new back tire is black. The store didn't have white ones, and I decided not to bother getting a matching new tire for the front.

Oh, I forgot to mention, I slapped a couple coats of varnish on the airbrake box plug, and also did some sanding and waxing on it.

One of the challenges of the weekend is that the parking lot is being resealed, so I couldn't drive up to the shop. Here you see how far I had to lug a 4'x8' sheet of 3/4" MDF by hand. You can also see the tire tracks of some car driven by someone who disregarded the closure ribbons.

The flaperon plugs with radius blanks hot-glued in place. I have them nested like this to conserve workbench space.

Six M10 bolts with retaining collars in place, three or four of them welded. I've found that MIG makes a really nice rosette weld for low-stress retaining collars.

The first six tools, with rotating collars in place. Still to do is to add the hex ends and their rotating hoods.

Flaperon plugs masked and ready for shmoo.

And so shmoo'd.

Homebuilt aviation is not for folks who don't try things at home.

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page updated 21 May 2007 all text and graphics copyright (c) 2007 HP Aircraft, LLC