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Old Jul 10, 2010, 05:32 PM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
Quote:
Originally Posted by Sean Oelofse View Post
Hey J, seems Rav has more than just 2 dings.....OH its a picture hanging on the wall
Looks are only skin deep!
The paint weighed in at.....
50 g

20% of the wing weight!
Can you believe it!!!
Well I suppose it was a tester...
And my 1st semi successfully bagged wing!
the live hinges worked well.

Hopefully i can get some work done tomorrow....
If the wind does not blow!
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Old Jul 11, 2010, 02:13 AM
Building with TLAR precision
Zenmaniac's Avatar
near Madison, WI
Joined Jan 2009
2,761 Posts
Quote:
Originally Posted by johannlochner View Post
Looks are only skin deep!
The paint weighed in at.....
50 g

20% of the wing weight!
Can you believe it!!!
Must be lead-based paint!

Ok, I'm officially in for this project. As a warning, this is my first scratch-built plane, other than a couple of coroplast and aluminum channel SPAD planes, so I'm going to ask some newbie questions to you gents. Hope I don't get to be too much of a pain -- just tell me to shove off if I am.

From what I can tell, my best bet will be a lost-foam pod. I'll be working on a Glass Sally, as the hills here aren't that great, and I think I'll get more flying time with a lighter plane (like my Alula) than a heavier one (like my Weasel). All I know about lost-foam modeling is learned from this http://www.favonius.com/soaring/lost_foam/lost_foam.htm and a couple of similar sites.


I spent an hour doing some sanding on a piece of foam, and got something that's threatening to my standing in the bedroom:

Looks like next I tape this thing up and lay on some glass. Now for some questions:

1. What weight fabric is recommended? Steve said he built his like a brick sh*t-house, but I don't know how to translate that to fiberglass. I have some 2 1/2 oz fabric on hand. Too heavy?

2. At what point do I cut the slot for the wing, cut the foam now before I apply the glass, or after it's glassed but before I de-foam, or after removing the foam. I'll be having a separate depron tail, and the foam would seem pretty fragile if I cut it now.

3. What about structural support in the pod? I was thinking I could inlay a couple of balsa strips into the foam, which could get incorporated into the fiberglass when it's laid on, and would remain after melting out the foam. Or add something later? or not at all?

Thanks for your help on the questions, and consider this my first posting on my build progress, as required from posting #1.

-= Dave
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Old Jul 11, 2010, 02:15 AM
Fly fast, Dont crash.
Thepasty's Avatar
Cornwall, UK
Joined Sep 2006
2,459 Posts
Quote:
Originally Posted by johannlochner View Post
The paint weighed in at.....
50 g
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Old Jul 11, 2010, 02:39 AM
Fly fast, Dont crash.
Thepasty's Avatar
Cornwall, UK
Joined Sep 2006
2,459 Posts
Hey Dave

My glass pod had about 3-4 layers of 200g glass and a carbon bandage where I split the pod... thats 200gsm, not sure how that translates to yards? It doesnt need to be lightly built as you'll need nose weight to balance. You wont need any formers or braces etc, I use a wood keel (balsa on the light glass version) to support the pod and mount the radio gear.

I cut the slot for the wing before I do any sanding (foams still in block form), I do mine with a hot wire so having 90deg angles on the foam makes things line up better. When the pod is sanded to shape I cut out the middle of the wing slot bit of foam so that it sits back in the pod with a little recess around the edges, its then taped and glassed.

Stick it in the vac bag and your pod will now have recessed glass where the wing slot is, the foam in the wing cut out stops the vac bag compressing it out of shape, once cured you have an easy line to follow with a cutting disc and simply remove the foam in the cut out and throw in some petrol to remove the foam.

Pod done.
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Old Jul 11, 2010, 03:28 AM
Building with TLAR precision
Zenmaniac's Avatar
near Madison, WI
Joined Jan 2009
2,761 Posts
Quote:
Originally Posted by Thepasty View Post
Hey Dave

My glass pod had about 3-4 layers of 200g glass and a carbon bandage where I split the pod... thats 200gsm, not sure how that translates to yards? It doesnt need to be lightly built as you'll need nose weight to balance. You wont need any formers or braces etc, I use a wood keel (balsa on the light glass version) to support the pod and mount the radio gear.

I cut the slot for the wing before I do any sanding (foams still in block form), I do mine with a hot wire so having 90deg angles on the foam makes things line up better. When the pod is sanded to shape I cut out the middle of the wing slot bit of foam so that it sits back in the pod with a little recess around the edges, its then taped and glassed.

Stick it in the vac bag and your pod will now have recessed glass where the wing slot is, the foam in the wing cut out stops the vac bag compressing it out of shape, once cured you have an easy line to follow with a cutting disc and simply remove the foam in the cut out and throw in some petrol to remove the foam.

Pod done.
Thanks for the tips, Steve. I found this: 1 oz/yd= 33.905748 g/m. 3-4 layers of your 200g glass will mean 8-10 or more of my stuff. Beefy!

Can you explain or show where/how you split the pod?

I like your idea of cutting the wing cut-out first. I should probably make a hot-wire tool -- maybe for now I can do it with a jigsaw.

-= Dave
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Old Jul 11, 2010, 03:38 AM
Fly fast, Dont crash.
Thepasty's Avatar
Cornwall, UK
Joined Sep 2006
2,459 Posts
I split the pod simply by sawing it in half, the keel then holds it in place with a bit of tape around the joint to secure it... nothing fancy, just functional.... I can get some pics if you want.

I set up my hot wire bow so that its vertical, you then run the wire through a paper template of the wing section and you got your wing cut out... accurate and no mess.

You could do the same with a fretsaw or the like.
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Old Jul 11, 2010, 03:45 AM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
I just love it when I can watch someone get sucked into the vortex....
Great stuff Dave!
Prepare yourself for a magic carpet ride!
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Old Jul 11, 2010, 04:10 AM
Registered User
Hexosex's Avatar
Cornwall, UK
Joined Oct 2006
1,089 Posts
Just as long as its not a red carpet! They are not so magic when it happens to you.

I was out yesterday with my sally at a ds spot in 10mph. Was great fun! Doing a few circuits and i touched the grass and picked up a long straw of it on one wing tip! must have been 2 foot long, anyways it kept on flying fine!!!

A few minutes later after doing some loops and rolls with this great big bit of grass on my wing i put it back into ds, was fine!

Whats with that lol, would have thought it would make the plane unstable but seemed to make very little difference!
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Old Jul 11, 2010, 08:43 AM
If it can-it will!
cliffhanger's Avatar
Gower South Wales UK
Joined May 2007
2,075 Posts
You sure you weren't smokin' the stuff!
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Old Jul 11, 2010, 10:30 AM
Composites Kid
Alex.Schweig's Avatar
Lima, Peru
Joined Jul 2008
3,122 Posts
Quote:
Originally Posted by johannlochner View Post
The paint weighed in at.....50 g
Don't wanna be rude, but WTH?


Dude! Was that like... white, liquid lead?

On a more serious note, what did you use? PU or acrylic?

PU tends to be very heavy if you spray it on thick.
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Old Jul 11, 2010, 03:20 PM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
Quote:
Originally Posted by Alex.Schweig View Post
Don't wanna be rude, but WTH?


Dude! Was that like... white, liquid lead?

On a more serious note, what did you use? PU or acrylic?

PU tends to be very heavy if you spray it on thick.
Hey Alex
At least I'm honest!

The wing weighed 204g once sanded smooth and filled.
I sprayed the 2k primer coat on fairly thick as I usually sand it down almost completely....
The finish was pretty good so I neglected to take off too much!
The white 2k then went on in two layers.....

I wasn't too careful..
B U T
It's now our big air proto!
And we'll fly the crap out of it!!
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Old Jul 11, 2010, 03:53 PM
Building with TLAR precision
Zenmaniac's Avatar
near Madison, WI
Joined Jan 2009
2,761 Posts
Quote:
Originally Posted by Thepasty View Post
I split the pod simply by sawing it in half, the keel then holds it in place with a bit of tape around the joint to secure it... nothing fancy, just functional.... I can get some pics if you want.
Thanks, Steve -- a couple of pix would be most helpful.

About the bagged fuse, I know mylar is used on bagged wings. What do you cover the fuse with during the bagging?

-= Dave
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Old Jul 11, 2010, 04:03 PM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
Quote:
Originally Posted by Zenmaniac View Post
Thanks, Steve -- a couple of pix would be most helpful.

About the bagged fuse, I know mylar is used on bagged wings. What do you cover the fuse with during the bagging?

-= Dave
Dave, you can wrap it in plastic (it won't stick)
Try the perforated plastic bags used for bread.
You then wrap it with paper towels that will absorb the bleed resin to avoid excess weight.
Have fun
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Old Jul 11, 2010, 06:33 PM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
Well done to Spain as the FIFA soccer world champs!
Now lets see if there is life after all that...

Oh, Dave
Be careful not to let the plug contort when under vac.
I'm not really sure it's necessary to do the layup under vacuum.
Just do it with the cloth 3m77 sprayed to the foam plug and wet out.
Use a light layer of finishing resin mixed with micro balloons once cured to avoid sanding the cloth layer.
Good luck!

I've had a most unproductive weekend!
I'll have to get back on track!
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Old Jul 13, 2010, 06:24 AM
Stirring the pot
johannlochner's Avatar
Port Elizabeth South Africa
Joined Jun 2008
4,025 Posts
Black is beautiful
Well, you can see every speck of dust and imperfection.
She's done at last!
I'll buff her down tonight and then start the polishing process.
The splitter board has to be cut to profile...
Then the mould!!


The vacuum pump has been a #@*x%# headache!

I cooked the previous compressor (I think it had no oil in it)
The vac regulator is still giving me a bit of trouble as it starts up at 10" and then clocks off the guage and doesn't switch off.
I think that's why I had some dents in my wing.
I ripped all the guages off and now have a very basic one.
Seems to work.
The 26000Btu compressor comes out of an AC unit and may be a bit strong.
I'll have to fiddle a bit more...
My wife wants to know..
To what benefit this ugly thing will have around the house!
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Last edited by johannlochner; Jul 13, 2010 at 06:35 AM.
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