Building Tips and technical articles. > Building techniques

The bluefoam model, or how to build a stunt plane without a bit of balsa?

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Istvan Travnik:
Dear Friends,
Succesfully I found a new place for my photos.
Please, visit my album here:

https://www.flickr.com/photos/171504164@N04/page1

Only bluefoam (Roofmate), some plywood, glass, carbon and epoxy. No balsa.
No lyrics, but questions are welcome.
Regards: Istvan (Europe, Hungary)  :!

MarcusCordeiro:
Video??

Marcus

Steve Helmick:
I looked at all the pictures, and found some very interesting details that could be easily adapted to more conventional models. I can't say I'm enamoured by blue foam construction, but somebody with balsa allergies might do well to consider it.  H^^ Steve

PatRobinson:
Hi  Istvan,
That is a clever and well done airplane and photo presentation.
Questions:
what are the specifications ? - wing area , wing span, tail area and span, fuselage length and etc.

component weights     - wing weight , fuselage weight, tail weight , hardware weight , total weight.
                                           How does weight compare to a built up wing or white foam balsa sheeted wing.
                                           How does your fuselage weight compare to a molded or standard balsa fuselage.
                                           How does your tail components weigh compared to built-up or solid balsa
                                           components.

Finishing Method   - It is unclear what method you used to finish this plane. Did you use epoxy finishing resin , with or without lightweight fiberglass as a substrate for your finish?  Blue foam can dent fairly easily so a hard substrate would seem to be useful.  What kind of primer and paint did you use?

My questions are to give us all a frame of reference to evaluate how your clever ideas might apply to other people's building plans.  

Finally, What were your reasons or objectives or rationale for adopting this method of construction?  

Once again, This is a great photo presentation. Well Done!!
                                                                                      Pat Robinson

sleepy gomez:
Istvan, I have been building with white one pound foam for forty years.  In the last few I have not used any balsa.  I developed and published the methods in 1974 when I was doing FF.  I have a table saw that lets me cut poplar to any size needed.  Being careful to balance size with strength I come close to balsa construction at a fraction of the price.  I use commonly available birch ply, .220" thickness for doublers, sometimes fuse sides, bell cranks and control horns.  I find the white foam to be of sufficient strength once it is encapsulated with spars and the normal silk span covering.  Silk span is applied with 50/50 white glue.  It is then sealed using a hot mix of unflavored gelatin. Once sealed any paint or dope can be used.  I do not sheet foam wings or foam stabs.   A note here is that with my income being Social Security I must build cheap.  An 800 + sq in area CL biplane only cost me less than $30.00 to completely build and finish.   No mine are not front row planes but they will fly with similar designs. 

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