HP-24 Project

Update 21 December 2004: Biased and plied

This weekend Doug Gray came back up to the shop, and helped me move the fuselage molds into the heated bay. He also helped a great deal to rearrange things in the shop so that we could actually walk all the way around the molds, and to impose some some sort of organization on my shop's natural chaos. That fun stuff was mostly on Saturday; on Sunday he helped me make templates for the fuselage composite plies, and to actually cut several of the plies to the templates.

The weekend ended sort of badly for me. On Sunday night, we sent Doug off home to Santa Clara, thinking that I would ride the commute airplane in on Monday to get to my office, also in Santa Clara. Well, come Monday morning, I rode the airplane in, all right, and then all the way back as well. The fog was so thick that we ended up with a missed approach and then returning all the way to Columbia. I actually saw the lights of the runway, but that was looking straight down on it. There was no way we could have made a safe landing, from what I saw.

After checking several possible avenues, I determined that there was going to be no way to get to the office that morning. So I bagged the day, and went to Bear Valley and went skiing with my family.

One of the most important things I've learned from Dick Schreder's legacy, and the legacies of other aerospace engineers and developers, is that aeronautic developments are too often advanced upon time stolen from daughters and sons - and that's time that they will never get back. So I do take conscientious effort to stop and weigh the time and trouble of what I'm doing, and what it's costing my family.

Anyhow, here's the weekend in pictures:

The rearranged (and still too messy) shop, with fuselage molds in place.

This is a ply of 7725 that Doug and I draped into one of the molds, taped in place, and then cut along the perimeter. Afterwards, we re-draped it onto the table and used it to make the first of several templates for the subsequent plies. The valuable (or at least expensive) lesson we learned doing this first ply is that masking tape will stick to 7725 like there is no tomorrow. We eventually gave up trying to remove the masking tape tags, and I will probably cut this ply up for patches and local reinforcements. I might try some acetone to loosen the tape, but I haven't decided for certain yet. Also noteworthy is that I've re-draped the fabric so that it is straight along the keel. I believe the fiber misalignment inherent in that doing it that way won't substantially affect the strength or stiffness, and I'm pretty sure that it will make it much easier to cut and arrange the plies.

This shot shows the nose area of that first drape, and the red-outlined template that I made from it on 4 mil poly sheet. It also shows the trauma we inflicted getting one of the masking tape tags off, and another tag that we abandoned in place. No, we won't be leaving any masking tape inside the molds.

The master drape template after some more work on it. The diagonal lines show where the +/- 45 plies will go; those lines are doubled to represent the 1" overlap where the pieces meet. It would be great if I could get rolls of bias 7725 or other easy-draping fabric, but I can't (at least not inexpensively) so I continue to work with what I can get in what ways I can. Also, note that there are two sets of diagonal lines. The red set is for layer 2, and the black set is for layer 4. Later, I'll be adding a third set, probably in blue, for layer 6, but only from the nose back to the mid-wing area. I have all these different locations for the overlaps, because I don't want the overlaps to occur in the same spots. That would result in an awkwardly thick layup in the overlap zones, which would disrupt the process of arranging the joggle flange that joins the right and left shells.

I should be back in the shop on 26 through 30 December 2004. The next order of business is to finish the templates and ply-cutting, and then cut the vacuum-bagging materials. Oh - I also need to finish cutting the joggle flange molds for the vacuum tape, and to make air-tight screw attachments for the flanges.Afterwards, we wax the molds, shoot the gelcoat, and then start laying up. At least, that's the plan from here. Disruption is always an option!

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page updated 21 December 2004 all text and graphics copyright (c) 2004 HP Aircraft, LLC