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Old Oct 03, 2012, 05:53 AM
I don't like your altitude
Stupot46's Avatar
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Thanks for the pics Kent.With glassing looming ever closer on my horizon all info is good.
Did you wrap one side of the cloth around the edges?
Never fails to amaze me how strong carbon tube is.
Regards Stuart
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Old Oct 03, 2012, 10:20 AM
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Quote:
Originally Posted by Stupot46 View Post
Did you wrap one side of the cloth around the edges?
No wrap. The vacuum bag process presses excess epoxy to the edges, so the LE has excess epoxy deposited there, which is sanded to shape.

If it were a wing, a strip of glass and kelvar at 45/45 can be laid along the LE before the skins are applied.

This little fin has more reinforcements in it's future.

Kent
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Old Oct 04, 2012, 08:01 PM
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Tail Boom reinforcement

Once the fin was glued to the black fiberglass boom, it was clear that it would be quite stiff for flying loads, but how strong would it be for one of my famous cartwheel landings. Rather than try to repair a broken boom after it is installed, I decided to throw 200K of carbon tow at it. 4 strands of 50K CF tow were wrapped in opposite directions around the boom then splayed out across the face of the fin. Much better. I’m ready to fly (and land) now. This leaves the center of the boom open for the antenna. I’ll do a range test to prove that the carbon wrapped boom does hurt the radio range.

Kinda lumpy....Kinda strong. I like it. The boom is strong enough now, so if the fin snaps off, it will be easy enough to repair with a fiberglass patch.

Kent

Plank 101 - Boom reinforcement (4 min 54 sec)
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Old Oct 05, 2012, 02:21 AM
Just call me crash for short
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You could of avoided those lumps, at least for the most part, if you would of finished it wrapping it tight with video tape. It works rather well as long as you get the shiny side towards the epoxy. You don't even want to know what a mess you end up with if you put it on backwards.

That aside, the fin and boom are looking real good Kent. Your arrangement looks like it will stand up to a full on discus launch, and if it will stand up to that, there should be no trouble with using it as a hold for bunggie / high start.

Mark
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Old Oct 05, 2012, 03:30 AM
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looking forward to seeing how she'll perform Kent!
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Old Oct 05, 2012, 09:44 AM
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Quote:
Originally Posted by Quick61 View Post
there should be no trouble with using it as a hold for bunggie / high start.

Mark
The idea of wrapping my fingers around the front of this lower fin and pulling back to 30lbs. has me a little concerned. I think that I have one more piece of glass for the LE of this fin.

I think that the lumps are mostly from the use of loose carbon tow rather than carbon UNI. The tow conforms better to the bend and twists around fin/tube joint. If I build another one some day, I'll use UNI and wrap with video tape.

Kent
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Old Oct 05, 2012, 01:26 PM
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Got Parts

A box of smokey laser cut goodness arrived. The fit between CF spar and laser cut ribs is perfect. It always amazes me how a part from one part of the world can fit so good from a part from another part of the world.

Kent
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Old Oct 05, 2012, 01:43 PM
Herk
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You are ready to roll
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Old Oct 05, 2012, 01:57 PM
I don't like your altitude
Stupot46's Avatar
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Old Oct 05, 2012, 08:04 PM
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Not so quick ! .... I'm not done torturing the fin yet.

The fin is getting a layer of Kevlar/glass cloth over the CF tow patch down to the lower fin. This is the launch handle. The cloth frays badly so I used 3M77 to attach it to a plastic carrying sheet. That assembly will get pressed with a stiff mylar sheet in hopes of smoothing the surface. The mylars are taped at the back edge to force the epoxy to the LE...... We'll see. It's in the vacuum bag now.

Kent

Fin Reinforcement for Handle... (2 min 18 sec)
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Old Oct 05, 2012, 09:09 PM
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Out of the bag.

This should hold up well to the launches.

Kent
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Old Oct 08, 2012, 02:14 PM
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Wing Assembly

Hot glued the ribs to the drawings, assembled parts and tacked all together with CA. Laid up some CF tow to extend spar out to wing tips, then epoxied all.

Kent
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Old Oct 08, 2012, 04:45 PM
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I like the idea of cooking the epoxy in the sun- whatever that is- today I took the tubes of epoxy out of my store cupboard and it was barely liquid!!! And it's not even winter yet!

Trev
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Old Oct 08, 2012, 05:10 PM
Herk
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Kent - the black on the edges of the ribs ???

Is that the paint you use for a sanding guide or something else?

Is it your plan that the wing will be fully sheeted ????
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Old Oct 08, 2012, 05:34 PM
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Quote:
Originally Posted by Crozzie View Post
I like the idea of cooking the epoxy in the sun-
This is what I like about epoxy. This slow cure laminating epoxy went off in about 20 minutes in the sun. Maybe 70 F in the shade. Inside the epoxy in the pot was still gooey hours later. When I mixed up too much epoxy, I've put it in the refrig. overnight before, and used it the next day.


Herk: black ribs fooled me too in the photos. No it's not carbon, just black paint. Only tiny area of solid skins on this bird. That's why the spar tube is so big.....to hold the wing twist. Top skins are shown in the attachment. Hatch in center at main ballast.

Kent
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