Thursday, February 08, 2007

Bagging a Delta -- David Kleynhans

Hi Evan

I am just writing to thank you for your excellent series of articles on vacuum bagging foam wings. On Sunday, I maidened my own design delta, which was constructed using your techniques. The first flight ended up in a tree due to having excessive travel of the ailerons which made the damn thing almost uncontrollable, but the damage was limited to a dented leading edge. After reducing the rates and increasing the reflex a bit, it flew absolutely beautifully.

The wings are sparless and skinned with two layers of 49g cloth at 0 and 45 degrees, and the weight for the entire wing came out just over 200g (span is just over 900mm).

Because the plane is an “oily”, and I don’t like spraying poisonous paints, I painted the foam using water based acrylic craft paints instead of painting the mylars.

This was reasonably successful, but you can still see dirty fingerprints and smudges through the fibreglass. You can also see areas where the cloth was not fully saturated, and the weave of the cloth is visible. This is a cosmetic rather than structural defect, as there are no soft areas on the wings.

I also deviated from your instructions by joining the root and tip panels before skinning and surprisingly this worked very well. I cut the mylars as you would for separate panels, and then taped them together using masking tape on the outside surface only. The masking tape stretches just enough to allow the mylars to conform to the different plan forms of the panels. After curing, there is only a very small ridge of epoxy that needs to be removed.

Overall, I found the whole process worked very well and I enjoyed using the new construction technique. Your articles were published in the SAMAA News in 2004, and it has taken me until now to get my act together and build a plane, but as you can see they did inspire me to try something new.

Kind Regards,


Link to Evan's article here

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