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Painting a plug? #266996
11/14/13 03:19 PM
11/14/13 03:19 PM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline OP
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Karl_Brogger  Offline OP
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Not boat related, but I'm making a plug to make a mould for one of my RC planes. I'm taking one of my smashed up EPP foam airplanes which is just a flying wing, no fuselage or tail. Think B2 bomber. I'm currently sheeting the foam with 1/16" thick balsa, and was planning on using thinned out epoxy over the top of that to kinda firm things up a bit once the whole thing is sheeted, then fairing and sanding from there. Then it would get painted and buffed out. What should the final paint be? Does it really matter as long as its a smooth surface that will release the part, (with wax obviously).

Just a project for the winter, and I've been thinking I could make one stiffer and lighter if it were just a hollow carbon shell. Won't hold up to impacts like the foam one does, but a stick built balsa one doesn't do to well in that respect either.

This is one that is just the foam with some carbon stringers a in it for reinforcement, wrapped in quite a bit of packing tape and then covered in monokote.

Top
[Linked Image]


Bottom:
[Linked Image]


I'm boatless.
-- Have You Seen This? --
Re: Painting a plug? [Re: Karl_Brogger] #266997
11/14/13 03:49 PM
11/14/13 03:49 PM
Joined: Jan 2009
Posts: 5,525
pgp Offline
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Tooling gelcoat?


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Painting a plug? [Re: Karl_Brogger] #266998
11/14/13 05:42 PM
11/14/13 05:42 PM
Joined: Jun 2001
Posts: 1,449
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phill Offline
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Karl,
I would spray Hi Build epoxy undercoat after it is faired and then rub that back with wet and dry 240 grit. The hi build will further improve an already well faired surface. Then spray it with polyurethane and cut the back with 600 and 1200 and then a cutting compound. When finishing the paint keep an eye on reflexions in the surface finish. Objects that can be seen in the reflexion on the surface will have their outlines sharpen and eventually become very crisp as the finish improves. I used a hand held shop fluro with very fine lines in the diffuser. Starts off as a mass of light and when finished you can count the fine lines of the diffuser in the reflexion.
At least that is how I finished the rudder plug for the
Farrier trimaran that I'm building. Gives a top finish.
[Linked Image]

Last edited by phill; 11/14/13 07:26 PM.

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!

Re: Painting a plug? [Re: Karl_Brogger] #267000
11/14/13 07:48 PM
11/14/13 07:48 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
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Jake Kohl
Re: Painting a plug? [Re: phill] #267002
11/14/13 08:15 PM
11/14/13 08:15 PM
Joined: Jun 2001
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South Carolina
Jake Offline
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errrr...or do what phill does. He's da'man.


Jake Kohl
Re: Painting a plug? [Re: Karl_Brogger] #267009
11/15/13 06:56 AM
11/15/13 06:56 AM
Joined: Jan 2007
Posts: 139
Hernando, Florida
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Mlcreek Offline
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Hernando, Florida
Karl,

You didn't say if it was gas or electric. If gas, you will need Dope or hot fuel paint so the nitro doesn't eat it. Electric, then whatever the guys suggest. Why don't you go back to monocoat?
Forrest


Forrest
I-20
USA 645

" There ain't enough rum in the drum!"
Re: Painting a plug? [Re: Mlcreek] #267011
11/15/13 08:52 AM
11/15/13 08:52 AM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline OP
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Originally Posted by Mlcreek
Karl,

You didn't say if it was gas or electric. If gas, you will need Dope or hot fuel paint so the nitro doesn't eat it. Electric, then whatever the guys suggest. Why don't you go back to monocoat?
Forrest


Electric. 2800KV brushless motor on a 7x5 prop with a 75amp ESC and a 50c 2650ma battery. I've wanted to try making one out of carbon since I got into this stuff, and this will be the plug for the mold. Just fun a project for this winter. My first plane was a Zagi flying wing, and they are still my favorite thing to fly. Best guess is with the foam cored ones I'm getting close to 100mph level flight with no wind. But what starts slowing them down, especially in high winds, is the lack of rigidity. The wings will start literally flapping. I think a carbon shell would be incredibly stiff, and I'm betting it can be made lighter.


Nitro fuel sucks. I'm done with it. Gas or electric from here out, though I do have a really bad butt Saito .80 fourstroke I really like but don't want to part with. My big gasser is covered in monokote.

27% Extra 260 I frickin' love this plane.
[Linked Image]

[Linked Image]


I'm thinking long and hard about getting one of these this winter. Not sure how I feel about having a $6k model airplane though. It'd get a 120cc boxer twin gas engine. All composite construction too.



I'm boatless.
Re: Painting a plug? [Re: Karl_Brogger] #267013
11/15/13 09:18 AM
11/15/13 09:18 AM
Joined: Apr 2012
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Bille Offline
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Posts: 190
Originally Posted by Karl_Brogger
Not boat related, but I'm making a plug to make a mould for one of my RC planes. I'm taking one of my smashed up EPP foam airplanes ...


Winter is coming, and RC airplanes are a good way
to go through the withdraw pains of not being able to
sail the Cat !!

That said :
If i were to go through the labor of molding an RC airplane
then i'd start with a new one, because your making your
airfoil proportionally thicker by adding 1/6" to each side.
Or maybe you Want to slow it down a bit ?

I LIKE flying the Zaggy ; that thing can be flown into the
side of a brick-wall, and only the prop will need replacing;
i've don it !!

Bille

Re: Painting a plug? [Re: Bille] #267014
11/15/13 09:40 AM
11/15/13 09:40 AM
Joined: Jan 2009
Posts: 5,525
pgp Offline
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Originally Posted by Bille
Originally Posted by Karl_Brogger
Not boat related, but I'm making a plug to make a mould for one of my RC planes. I'm taking one of my smashed up EPP foam airplanes ...


Winter is coming, and RC airplanes are a good way
to go through the withdraw pains of not being able to
sail the Cat !!

That said :
If i were to go through the labor of molding an RC airplane
then i'd start with a new one, because your making your
airfoil proportionally thicker by adding 1/6" to each side.
Or maybe you Want to slow it down a bit ?

I LIKE flying the Zaggy ; that thing can be flown into the
side of a brick-wall, and only the prop will need replacing;
i've don it !!

Bille


laugh


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Painting a plug? [Re: Karl_Brogger] #267016
11/15/13 09:45 AM
11/15/13 09:45 AM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline OP
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Either way I need something to start with, but I do know what you are saying. I was actually just thinking about that early today, I'm not sure how much I'm changing the foil. It's getting thicker everywhere. I don't know? Beyond my comprehension... blush

The other thought was to get another one and glass it. The change would be minimal that way. It could be done with some ridiculously thin glass.


Originally Posted by Bille
I LIKE flying the Zaggy ; that thing can be flown into the
side of a brick-wall, and only the prop will need replacing;
i've don it !!


It by far the toughest design out there. I've gone through a few... I pounded one into the ground so hard the motor and speed control couldn't be found. Landed/catostophically crashed in a damp freshly tilled field. The one I'm attempting to make the plug out of pancaked into dry hard ground last fall. Popped all three carbon spars in it. lol


I'm boatless.
Re: Painting a plug? [Re: Karl_Brogger] #267017
11/15/13 09:47 AM
11/15/13 09:47 AM
Joined: Jan 2009
Posts: 5,525
pgp Offline
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You definitely need a Hero so you can get some vids of the action.


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Painting a plug? [Re: pgp] #267019
11/15/13 10:05 AM
11/15/13 10:05 AM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline OP
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Originally Posted by pgp
You definitely need a Hero so you can get some vids of the action.


Racine Yacht club a couple of years ago. This is actually the dead wing I'm sheeting.


Turn the volume down. A electric motor spinning at 22k rpm is not a pleasant sound.

Last edited by Karl_Brogger; 11/15/13 10:06 AM.

I'm boatless.
Re: Painting a plug? [Re: Karl_Brogger] #267020
11/15/13 10:20 AM
11/15/13 10:20 AM
Joined: Jan 2009
Posts: 5,525
pgp Offline
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Cool!


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Painting a plug? [Re: Karl_Brogger] #267024
11/15/13 12:57 PM
11/15/13 12:57 PM
Joined: Apr 2012
Posts: 190
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Bille Offline
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Joined: Apr 2012
Posts: 190
Originally Posted by Karl_Brogger
Either way I need something to start with, but I do know what you are saying.
...


Here's a 60" one that might carry your camera better
because it's got more aria ; hard to rationalize
molding & making one for $69 ;
http://www.hobbyking.com/hobbyking/..._Combat_Flying_Wing_EPP_1525mm_KIT_.html

Also, if your making one with EPP foam, then you Don't
need a mold, you need a Hot-wire.

Bille

Re: Painting a plug? [Re: Karl_Brogger] #267352
11/27/13 04:30 PM
11/27/13 04:30 PM
Joined: Mar 2009
Posts: 932
Solomon's Island, MD
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samc99us Offline
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Joined: Mar 2009
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Solomon's Island, MD
Karl,

I might be able to help you out, I'm getting the CNC router up and running over Christmas. Plan is to cut foam for now but might move to MDF and Corian eventually for female molds. Really you don't need a mold for a flying wing, foam does fine.

Still, if you insist, make the plug as smooth as you can. Hand sanding molds is a real pain, but done right you can get some nice finishes. This is wing #5 of 18, before the PVA was removed, so its still dusty.

Attached Files
IMG_2688_small.jpg (16 downloads)
Aurora DLG

Scorpion F18
Re: Painting a plug? [Re: Karl_Brogger] #267361
11/28/13 10:18 AM
11/28/13 10:18 AM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline OP
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Sam, are you saying just to glass over the foam core? Currently these things come cnc wire cut out of EPP foam. I don't know about the weight vs another kind, like of the insulation variety (can't think of the type of foam that is).

I'm open to ideas. Like I said, I'm shooting for stiffer and lighter.


I'm boatless.

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