** PIRANHA! ** - 43" fff/monoblock/kfm4 aerobat - Page 66 - RC Groups
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Aug 06, 2017, 06:24 PM
I meant to do that. Honest!
JamesPotts's Avatar
As long as the wing is still parallel with the stabilizer I don't see much reason to worry about it. The pics look like the skew might be causing some right motor thrust but that is usually a good thing. I personally would try flying it as it is and see how it behaves before trying to fix something that doesn't cause any problems.
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Aug 06, 2017, 07:16 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
I went ahead and inserted some foam and glued it up using a framers square to check and make sure I didn't push anything out of line. It came out pretty good, it got the top pushed back out where it belongs.

Your assessment is exactly what a flying buddy said. I'll take a stash of washers to the field to set the appropriate down and right thrust once we all have a look. Maybe I can get out Thursday afternoon.
Aug 06, 2017, 07:54 PM
Jack
jackerbes's Avatar
One way to get more strength in the front or nose of a foam fuselage is to put a block of foam there that extends back 1-1/2" or 2" or so and then use a firewall with dowel legs like the ones in the image. That is fitted with the foaming Gorilla glue and essentially spreads the loading out over a deeper and larger area.

I started doing that when I found the bond between a plywood firewall and a foam surface just did not have any depth to the strength and was easily jarred loose.

The image is the firewall fitted to the Big Blu glider's foam fuselage. Only three of the four dowels are fitted, the holes in the foam were make with a brass tube drill and slightly over sized so the foam would have some room to fill. That fuselage was all foam and had a fishing rod blank in a hole drilled full length. The fishing rod was also retained with Gorilla glue. Very light, very strong...

Jack
Aug 06, 2017, 08:44 PM
I meant to do that. Honest!
JamesPotts's Avatar
I too have some very minor repairs to make on a small balsa biplane that managed to find a 3 foot high chain link fence this weekend. Just a few covering patches and a new prop and she'll be right again but it still cuts into my build new airplanes time. Rats!!!
Aug 11, 2017, 08:14 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Ugh, I can't seem to get anything airworthy to the field except for my HZ Super Cub LP...

Servos came loose (they were hot glued in)... better use a different and more secure method.
Aug 13, 2017, 03:40 PM
I meant to do that. Honest!
JamesPotts's Avatar
Yeah, I don't trust hot glue for servos. I glued some 1/8" ply squares to the fuse with epoxy and screwed the servos to them. I roughed the surface of the foam first to give it some tooth.

I changed the motor on my Piranha. I went to a slightly larger more powerful one with a lower KV so I could swing a longer prop. I'm very happy with the results. The vertical performance is perfect now and the top speed is good enough for fun flying and 3D aerobatics. I think I'm done tweaking it now.
Aug 13, 2017, 04:20 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
I had a plywood plate I salvaged from the trash can at the field, cut some ply pieces from that for the screws and used foam safe CA to glue them to the fuselage. The servos are now tight.

Didn't make it to the field today, maybe I'll get out late in the week. I think she'll scoot now.
Aug 14, 2017, 02:33 PM
I meant to do that. Honest!
JamesPotts's Avatar
Quote:
Originally Posted by jackerbes
One way to get more strength in the front or nose of a foam fuselage is to put a block of foam there that extends back 1-1/2" or 2" or so and then use a firewall with dowel legs like the ones in the image. That is fitted with the foaming Gorilla glue and essentially spreads the loading out over a deeper and larger area.

I started doing that when I found the bond between a plywood firewall and a foam surface just did not have any depth to the strength and was easily jarred loose.

Jack
I tried this today on a repair. The firewall had separated from the EPS monoblock during a hard landing (or a light crash if you prefer). It seems to have worked very well and the motor feels more solid now than ever before. Thanks Jack!
Aug 16, 2017, 07:13 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by JamesPotts
I tried this today on a repair. The firewall had separated from the EPS monoblock during a hard landing (or a light crash if you prefer). It seems to have worked very well and the motor feels more solid now than ever before. Thanks Jack!
You are welcome! Now you can land harder!

Jack


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