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Old Sep 04, 2005, 03:54 PM
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RNAF's Avatar
The Netherlands
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How would you convert a stick & tissue model to a foam model?

Hey lot!

The title says it all:
How would you convert a stick and tissue model to a foamy model?

An example; a Pres Bruning model converted to a complete foamy.

I've given this a lot of thought. I found that it's pretty hard to do since there's a lot to change. For example if the model's made from 2 mm foam. How would you do this? How would you convert a model that hasn't got any formers?

The attachment is a model made the same way Pres Bruning usually does (Pres makes the coolest models, like the Cessna Caravan, Pilatus PC-9 etc.).
The sides are flat built up frames with a few formers that are located on the top and bottom. That way "full formers" aren't needed and saves weight. That's the main problem converting such model to a foamy: there are no formers.

I hope replies will be as helpful to me as for other scratch-foam-builders!

Dave
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Old Sep 04, 2005, 04:00 PM
Got shenpa?
flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
10,940 Posts
Maybe I'm missing something, but you can always use foam for the slab sides, and put in foam bulkheads/formers where you need them.

Things get much harder if the body has a circular or elliptical cross-section, as you can no longer use flat slabs of thin foam. But in this situation you can either use slabs of thicker foam for walls and sand them to shape, or build up the entire fuse from a stack of "formers", each cut to the cross section of the fuse in that area.

You might consider buying Keith Sparks book, "Building with foam" :
http://www.darehobby.com/books-01.htm

-Flieslikeabeagle
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Old Sep 04, 2005, 05:35 PM
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J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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It is not that difficult.
Use side and top view. Use two large enough pieces of pink or blue foam(2" thick) tack glued together. Draw side and top views, hot wire cut, then carve to shape.
Separate the halves, hollow out for equipment.
Wings can be hot wired or made from fanfold ( Bluecor).
Here is my Me-109E from balsa plans by Ian Peacock.
Has pink foam fuse, fanfold wings, many,many flights on Mega 16/15/4, 2.5 GB.
Flies as good or better than the original at a lower weight.

J
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Old Sep 04, 2005, 06:41 PM
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Humble Texas
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I don't want to cop out, but do a search for any thread by Vyceroy . He has made more circular or elliptical cross-section planes using fanfold than most anyone (and some very beautiful ones ).
Johnnie
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Old Sep 05, 2005, 06:39 AM
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Well, the point is, I actually wanted to see how others would do it.
I've been around here for quite some time and I never saw anything that's simillar that what I intend to do.

Flieslikeabeagle, that was the whole point. How to make a stick and tissue model in foam. Stick and tissue model's don't have "full formers" that's what I need. I do get your point, though.

Dave
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Old Sep 05, 2005, 12:48 PM
Got shenpa?
flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
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Dave, perhaps I still don't understand, by full former do you mean a bulkhead with no hole in the middle? Because, of course, foam bulkheads/formers can also have a hole in the middle. If you use Blucor (with the thin skin left on), or even foam-core posterboard with the paper left on, you can cut quite a big opening in the center of a former, and it will still have quite acceptable strength and stiffness.

J Morgan, I've seen some of your planes before, but I still marvel at your beautiful creations. You really do make flying works of art!

-Flieslikeabeagle
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Old Sep 05, 2005, 07:05 PM
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Central Ohio
Joined Feb 2003
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RNAF
See that you are in the Netherlands, which means you will most likely be building with Depron. Suggest you read through Martin Chouís thread on building with sturdyboard/Depron.
http://www.rcgroups.com/forums/showt...1&page=4&pp=15
Depron is more brittle than Blucor, which makes it harder to bend those small radius curves withoout cracking the foam. Martin shows how to do this.
Don
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Old Sep 05, 2005, 10:09 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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beagle,
Thanks, appreciate those nice words.
Dave,
If by formers you mean bulkheads like a Guillows model then it can basically be done the same way. That is how I did my Mig-21 fuselage except I built it like you would sheet a stick model. I used a keel and put in the top half bulkheads and then sheeted it with bluecor. Then turned it over and did the bottom the same way. I did a buid thread on it in jet pushers forum which shows some on the build pics.
Getting ready to do a Me-163 like this and will probably do a thread here in foamies on it. Here's the round fuse of the Mig......

J
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Old Sep 06, 2005, 05:57 AM
I'm not flying backwards!
Tony65x55's Avatar
Oshawa, Canada
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John, your work is AWESOME.

Tony
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Old Sep 06, 2005, 07:49 AM
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Flieslikeabeagle,
as you see in the attachment, the plane only got some top and bottom formers. Since a derpon build up is somewhat different than a balsa built up, I need formers that you would see in a "normal" balsa model. That mean drawing own formers by using the plans. I just wonder how other people do that.

Defranci,
I know how to work with depron, thanks anyway
Nice thread, though!

Dave
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