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Aug 31, 2020, 01:30 AM
Father by day, hacker by night
JornWildt's Avatar
I use the kitchen oven for vac-forming. Makes it easy to get even and consistent heating of all the material at once. About 175 deg. C.

Another important thing is to get the bottom of the frame sealed against the board as fast as possible. Any air gap reduces the amount of vacuum pull you get before the plastic cools down: move *fast* out of the oven and press the frame *tight* against the box *asap*.

If your board with all the holes in it is too weak, it too will sag when you press the plastic over the plug, sometimes to a point where airgaps start to open up around the edge. I usually put a book in the box, with for instance lego blocks on top, to support the board from the inside.

More holes! Plenty of air holes in the board

Sprinkle some talc on the plug to get the plastic off easier.
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Aug 31, 2020, 03:56 AM
Big gov never Works
St. Martin's Avatar
Fortunately, the fillets are not a huge thing on the Mustang, Ronald. Some soft tri stock, shaped should do it. You can cover them and attach w/silicone. But, they do make a difference in the frames appearance.

Fuzz
Aug 31, 2020, 08:45 AM
Still the "Pro"-crastinator...
Steve85's Avatar
Quote:
Originally Posted by JornWildt
I use the kitchen oven for vac-forming.
I read that and all of a sudden my wife's hair caught fire. I can't imagine what kind of horribly slow demise I'd meet if I tried to melt plastic in Her oven...

For many years I've successfully used a small toaster oven bought for less than $50 at Walmart for heating plastic for vac forming.

Steve
Sep 06, 2020, 02:52 PM
Registered User
Thread OP
I'm happy to report a successful and easy maiden flight!

Unfortunately, no video or pics. So you have to make do with my prose

I went to a nearby club that has a nice airfield, even with a tarmac runway. The FMG Waldalgesheim, really nice people! After a last check of all functions and control surfaces I just went ahead and throttled up slowly. I wasn't able to keep the P-51 on the runway due to a cross wind. But lawn is a good runway, as well . A slight pull had in the air rather quickly. A sudden drop of the left wing had me on my toes, probably a gust? Some more throttle and right aileron and everything was under control.

Once at a safe height, I had to trim a bit down but that was all. 50% throttle was enough for a nice cruise speed. On the next round I flipped the switch for the retractable landing gear. That worked ok, as well. So next I tested the stall characteristics. Nothing awful happened. That had me relax some and enjoy the Mustang in flight. It feels rather nimble, maybe I could turn down the control surfaces throws a bit. With throttle it speeds up nicely, without any ballooning or so. It pulls up to a nice, wide Immelmann turn and a wing over worked, as well.

Strangely, the canopy isn't very prominent in flight. I often couldn't see it, which made the silhouette look wrong. I will still add a pilot bust, but could also tint the glass to make it more visible.

The first landing was a bit hard, but the second already much smoother. I was happy, that the retracts weren't harmed. My biggest fear was, they would just get ripped out on the first touch down.

All in all, I'm really happy! I learned something more during this nearly one year build. The plane came out really nice (still details to add). And it flies really good, as well.

Some stats:

scale 1:10
1.13m span / 44"
1200 g all up weight / 42ozs / 2.6 lbs
24dm˛ wing area / 372 sqin / 2.5 sqft
50g/dm˛ wing loading / 16.4 ozs/sqft
10.2 oz/cbft

3542 motor with 900 kV
11*8 APC prop
3S2400 lipo
350W input power
3S2400 lipo

Best regards
Ronald
Last edited by Ronald L; Sep 06, 2020 at 02:57 PM.
Sep 06, 2020, 03:07 PM
Tomorrow I'll procrastinate
Congratulations. I'm glad it was a successful flight.
Martin
Sep 06, 2020, 08:06 PM
Still the "Pro"-crastinator...
Steve85's Avatar
Congratulations on a successful maiden and a great build! I think it goes to show how Earl Stahl's timeless free light designs, built by a capable modeller, are still relevant in today's context of electric flight. Great job Ronald!

Steve
Sep 07, 2020, 02:07 AM
Father by day, hacker by night
JornWildt's Avatar
Congratulations!
Sep 07, 2020, 07:02 AM
Merlin impersonator
balticS2's Avatar
Great result Ronald. Would make a nice addition to any hangar.

Alec


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