Update 9 March 2004: Good and good
The caveat to yesterday's update is that it's not over til it's over. When you close up a big vacuum-bagged layup and then drive away, it's not necessarily guaranteed that you're going to get what you expect when you return.
In specific, the short list of things I've learned to worry about is A-T-P:
- A is for alignment. Did the fixture perform as expected, and did the part maintain its relationship with the fixture? I worry about this because I've had to implement my share of fixes to make things come out straight.
- T is for temperature. Did the temperature stay at a reasonable level throughout the cure? I worry about this because the power in Arnold is a bit iffy during storms. If you cool the resin below its range before it finishes curing, it might not finish curing at all. Almost all polyesters and most epoxy resins will, but some won't.
- P is for pressure. Did the pressure or vacuum stay applied as expected throughout the cure? I don't worry about weights like my paving stones; near as I can tell, my gravity bill is paid in full. But again, in Arnold power is a concern. If the power goes out and the vacuum pump goes off, it would really make a mess out of one of these uphill layups like the last two. The pump has a 10-gallon reservoir, and my bags have been pretty tight, so a few minutes without power would be no problem. But a three-hour stretch would probably yield an unusable part. Also, I worry that the hoses might come unplugged or a seam might loosen or unzip.
Anyhow, last night I went up to the shop and checked, and the last layup had cured just fine. It looks like I'm good to go to join the inboards and outboards together, and start sanding and grinding them down to smoothness. I've got some big pieces of glider tooling now!
Also, last night I got a call from Doug Gray to let me know that he'd delivered the aft fuselage plug to Precomtec R+D. So as soon as they finish the canopy frame, I can place a contract for the 70" of missing fuselage surface and for the whole-fuselage molds.
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page updated 9 March 2004 all text and graphics copyright (c) 2004 HP Aircraft, LLC