|Apr 16, 2014, 11:52 AM|
Balsa to foam build???
I don't want to read over a thousand pages to find something and a search didn't
give me any thing useful. so......
I have plans for a 48" Jenny. Done in balsa. Since it is a simple design, I was thinking
of doing it in foam. Cut out all the parts, lighten the internals. leave a section of
paper on the edges for gluing. Doing a one piece folded wing section with
a foam spar reinforced with light ply. Use poster board for the sheeted parts.
Remove the paper on the inside parts. And on the inside of the fuselage sides
Thinking maybe a three to three and a half pound plane? 10 size motor on 3s.
|Apr 16, 2014, 12:54 PM|
to the wing. Even want yellow...
Going to get an ink cartridge for the old printer and go for it.
|Apr 17, 2014, 10:55 PM|
Just as you recently discovered with your ft plane, when using foam, you don't really need all the structure as with traditional balsa builds. The thick skin carries a lot more loads better than monocote. So you could do a decent Jenny just by using a 3 view.(boxy fuse, simple wing airfoils). Cutting out all the bits from a balsa plan can certainly be done, but will make a heavy, complicated tougher to repair plane. A typical build 48" foamie should weigh a lot less than 3.5 lbs and fly well (lighter fly's better!) My 30" span OneSheetBipe comes in at less than 10 oz ready to fly, and the 56" span superTwin is probably only 20 oz or so (have to measure it)
It is a different paradigm and opens up a whole new arena to play in.
|Apr 18, 2014, 01:57 AM|
The plan is to lighten the inter structure as much as possible. Just there to give it the right
This is a bit crude, but you get the idea. Of course there won't be any strings, that part will
be covered with poster board.
This may be a learning model, and never flown, we will see as we go. Haven't printed
the plans and patterns yet.
Thanks for the info.
|Apr 18, 2014, 09:39 AM|
Good plan! My comments were coming from your mention of "cutting out all the parts", which made me think about all the myriad of parts that are typically in a balsa build attempting to get a strong structure. Combining many of them and eliminating others is the way. I generally use a full former only where something is happening in the structure, like nose/firewall, wing LE and TE, and at a fuse section change. The typical early bipes with box fuse had a straight cross section from nose to aft of cockpit, then plan view (and side view) taper, so I put a former at that transition point, and skipped any formers aft of that, relying on the foam thickness to provide the section strength.
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