HP-24 Project

Not long after the last Update I fell ill with some sort of cold that's been going around down here in the Silicon Valley. For a while I felt a bit woozy and apathetic, then for a few days I didn't even have the energy to feel woozy. Then I went back to feeling sort of OK if not particularly energetic. Then back to the no-energy state, which I mostly spent in bed reading Henry Petrosky's Engineers of Dreams and Rushdie's The Satanic Verses. And then a couple more cycles of the whole thing of the next three weeks, interspersed with semi-compulsory attendance at long-standing social committments.

It was only in the last two weekends that I got anything of note done up at the shop. I sanded out the lower right wing mold, and then this last weekend Doug and I managed to get (mostly) ready to make a mold for the lower elevator surface, and we also laid up a lower horizontal stabilizer skin.

The pictures pretty much tell the story about the days I felt well enough to get anything done. Here they are in chronological order:

22 September 07: I'd made arrangements with Werner Braun to borrow his Dillon 10,000 lbf dynamometer to calibrate my homemade Break-O-Tron hydraulic Dynamometer. But how to fit it into the car with all the gear required of a Yosemite camping weekend? Answer: Make the wheels detachable.

Notice the new slip joint I welded up out of four rectangles of steel.

Overview of the whole Break-O-Tron machine.

23 September 07: I made this for a geocache for Alia. I'm going to rust it in various caustic solutions and then conceal it among a bunch of similar ironmongery.

29 September 07: I'm feeling well enough to attend the annual Yosemite Climber's Association Yosemite Facelift, at least on the Saturday and Sunday. I'm not up to the camping and campfire stuff, but fortunately Brigitta arranges a tent cabin for us. This is the mound of garbage they'd collected by the time we arrived Saturday morning.

Here we are dressed for cleaning up! Most of what we cleaned up was bits of wrappers and cigarette butts. It seems that most folks are fairly conscientous, but that the tend to lose track of the small stuff. Hence we found many many corners of granola bar wrappers, tiny adhesive labels from apples, and many iterations of our new arch nemesis: the juice box cellophane straw wrapper. And lots of cigarette butts. Somehow it seems that too many Yosemite visitors don't consider cigarette butts to be garbage. That must be so, considering the volume with which they cast them upon the landscape with a drop and a casual stomp-twist. Helllo, Yosemite visitor people? See any cigarette butt bushes around here? Take a hint.

That afternoon I went over to the Yosemite Search and Rescue SAR Cache where I used Werner's dyno to put together a quickie calibaration chart for the Break-O-Tron. Then YOSARian Majid Sabet and I did a couple quick tests of webbing and cordage threaded through climbing bolt hangers.

Sunday, more of the same. This stuff caught my eye, it's a television set (the picture is a poster taped to the screen) and an electrical substation control panel, both discarded within park boundaries. All told, the Facelift removed about 42,000 lbs of trash from the park. About 32,000 lbs of that was abandoned infrastructure (such as the pictured control panel) that the Nationa Park Service had no funding to remove. The family and I managed a total of 40 lbs for the two days, of which a substantial portion was lightweight-but-very-visible stuff like the aforementioned straw wrappers and cigarette butts.

Here Raen poses with some of the 21 tons of trash the Facelift accounted for this year. I found the arrow-shaped thingy just above and to the right of photo center.

Fast forward to the morning 20 October: Here's Panda, the latest addition to our household. She's a border collie mix that Brigitta picked up at the pound. Two days after coming home with us she fell ill with Parvo and barely came through. She's doing fine now.

That Saturday was the first real HP-24 shop day in several weeks. Here's part of the mess we cleaned up - it's dust left from the flaperon radius cutting operation, in which were scribed these mysterious hieroglyphics.

We started by moving the lower right wing mold out. In earlier weeks, we'd scribed it with the flaperon hinge radius and used it to attach the hinge gudgeons for the flaperon plugs (the ones for the radius cutting operation). And after that, I'd sanded it it up from 320 grit to 1500 grit, done a course with polishing compound, and applied one coat of wax. Now it was time to go back onto the stack. Here's Doug and I using the stick hoists to lift it up so we can roll the stack under it.

Sunday 21 October, here's Doug and I after laying up a lower horizontal stabilizer skin.

It bagged down pretty well, and we got good vacuum on the first try. The grid of circles is where resin is bleeding through our homemade perf ply between the peel and the bleeder. It's a bit soupy in spots, but in general just fine for a development part.

Here's the elevator lower surface, almost ready for molding. We used the upper horizontal stab mold as a platform.

When we left the Yosemite Facelift on Sunday 30 September, we took with us eight of these pick-up tools that had gotten broken. Mostly they fell victim to broken spot welds on the stainless steel bands, though a couple also had broken trigger pins. I managed to fix all eight of them, though for six of them I had to shorten the whole tool by 6" to yield bits of replacement band, which I rosette welded with the MIG box. I think that's a good thing - now they'll have at least six such tools of a kid-friendly size. Here I'm painting the tools yellow to distinguish the shorties from the rest of the tools. Now I just need to get these back to Ken Yeager before next YCA cleanup event.

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

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