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Foam Quark

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johnfireball:


Hi all,
     Having never worked with foam before I have decided to have a go at making a foam 1.6m Quark as per Freds plan. Two unsuccessful attempts with an assistant at wing cutting in one go I decided to try it in two stages.I started by cutting blocks of foam 5mm all round bigger than wing size  I soldered wires to the templates(in the pic the wire is broken off the back of the root template, I caught it in my jumper). I double sided taped the templates to the block ends (checking allignment) and with an assistant managed to cut 2 opposite and useable wings in two passes per wing of the hot wire.  They needed a little sanding to remove lines caused by slow wire speed at the wingtips. Cutting wings this way requires a little sanding of the leading edge ( you can see the waste that needs removing on the leading edge in pic.) and cutting a sliver of foam from trailing edge using a knife and steel rule.
             The small wing below the foam is a test piece which has the same profile as the quark wing. After it was cut I rolled it with a coat of PVA glue, allowed it to set off somewhat I then glued out craft paper using the same glue and roller and covered the wing top and immediately after covered the bottom and then weighted it down to dry. The result is a good stiff wing which hardly requires a spar although I will fit one.
            Paper finish is difficult to paint so I will most likely be taping also.
John.

johnfireball:



Some progress, have glued in 5mm solid carbon spar and tubes for 6mm wing mount. I used my soldering iron with a ruler to melt out the spar channels. The incidence pin tube is 5mm brass with 4mm carbon pin. I have taped  carbon strips to the trailing edges and will hopefully get a better sharper finish.
   I have tried a water based varnish to seal the craft paper and it works really well as a base coat for spray paint, so might not use tape. Waiting on lightweight filler to dry and will then cover.
John.

Fred:
Hey John,

This is looking very good.
Are you going to use the same foam to make the fuselage ? :clap:  :clap:

johnfireball:
Hi All,
      Some more progress made.



 I had to laminate foam pieces together as my foam was not thick enough. I cut the templates from hard cardboard 1.4mm thick, they work but not great (cutting wire catches).

I have now covered the wings and completed the tailplane which I made from foam  sanded to shape, added carbon trailing edge and covered.
 The wings are now weighed down in their outer covers and will remain there for a few days to dry out. The paper and pva dry out very rigid and hopefully wont warp. This so far is the cheapest model I've built as all materials I had to hand. It's a bit of an experiment and learning as I go but  so far pleased with results. It's my thrifty recession Quark.
 

John.

mario:
good job :wink:

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