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Friday, April 25, 2008

Ventus no4

The progress on Ventus no 4 has been rapid to say the least, this has been one of those projects were everything has just gone smoothly(or is it practice).
In the photo below the servo tray has been bonded in and below it you can see a strip of 200gr carbon cloth which ties the two sides together and stiffens the belly which takes strain in the landings.The forward cut out is for a tow release servo , aerotowing being a new field for me altogether but worth a try later in the year.
In the photo below you see the blue foam cores being prepared , A tip here is to mask up the grove on one side and place your straight edge on the masking tape, once the grove is correct(ie, wider or deeper at the root to accept more carbon tows) Then you mask the other edge, wet out the tows and layup the spar being carefull not to get any resin on the cores, normally these drips get wiped but leave hard areas which show up on the bagged wing. Now once the wet tows are all in, use a plastic card to flatten them but screeding across the masking tape , once happy remove the masking tape and leave to cure. If you grove is slightly hollow/deep you can fill with a mix of resin and balloons and again screed to get a level finish.

This photo shows the fuselage being modified for the thicker airfoil , you can see the infill on the wing shoulder, this was done by cutting two balsa root ribs , sanding the area and then gluing them onto the fuselage, I then filled the contour with a mix of resin / balloons /and flox finally sanding to shape and then respray with 2k.

Boxing smart not hard, the end ribs (ply-wood)are cut to size, bonded on and then sanded to match the cores, I normally glue them on afterwards but this is better as it will now have glass across the join, lighter and stronger.
The leading edge is strengthened with 3 x 12 k carbon tows and smoothed prior to vacumn bagging on the skins, which are 1 x 104gr and 2 x 163 at 45 degress I use Epolam resin system on the wings. As I post this the wings have already been bagged with no problems and appear to be in the weight region of 2000grams, but need final cleaning up and control surface cutting, this is about 500 grams per wing lighter than no 3 but they feel as rigid, this may also be due to the thicker foil section.
I will post the final pictures of this build early next week.
What next? It has to be a built up vintage glider after seeing these at the Sungazer,
I have already picked a subject and need to get some drawings and rediscover the smell of balsa-wood and white glue.
Cheers for now.

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