Jim.Thompson's blog View Details
Archive for May, 2014
Posted by Jim.Thompson | May 21, 2014 @ 04:48 PM | 14,831 Views
I have been busy learning to draw in 2D LibreCad, which is an open source CAD drawing system designed specifically for Linux. That has been a challenging but very rewarding adventure in itself.
Also, I've been working on the design of my next project; Entropy build thread here:
https://www.rcgroups.com/forums/show....php?t=2164114

Also I have been doing a bit in the shed building another light plank out of the remaining scrap foam that I salvaged from the tip. This one will be very similar to the 1200 I finished recently (flew again yesterday - very nicely too), but will be 1400 span. The max size panel that my gravity cutter can cut is 700mm, so that determined the size. I expect to be able to make this one to an even lighter wing loading that the smaller one. I've learned a few more tricks along the way, as happens.
Posted by Jim.Thompson | May 02, 2014 @ 04:17 PM | 14,625 Views
I built this foam plank heavy with view to Dynamic Soaring it. I hope to travel up to one of the DS sites where some of my flying pals fly regularly. There are no DS sites to be found around where I live.
This plank has an AUW of 1850 grams, which makes it a bit of a heavyweight.
Span: 1500mm
Airfoil: PW51

The finish method went as follows:
1. After the wings were shaped and sanded, I applied powder filler (not the pre-mixed type) in the usual way. Sanded, then another coat etc. till smooth. Usually three applications.
2. Then I screeded a coat of PU glue over the surface with a hard plastic spreader. This really made the spackle nice and hard and formed a smooth glazed surface. Sand, second coat. Sand. Very little sanding required this way.
3. Spray adhesive applied, then two layers of crossweave tape diagonally opposing. (45/45 orientation).
4. Degrease, then lay flat with covering iron. Sand lightly with coarse paper to scuff it up a bit.
5. Spray adhesive applied again, then covering film to decorate.
6. Finally, another mist of spray adhesive and a layer of 30 micron laminating film applied..
7. The elevons were bagged glass over balsa, with some light uni-carbon strips top and bottom at the TE. This made for nice and stiff elevons.
8. The fin is vac Bagged foam core. Carbon/glass.

I hope to get out to Mt. Borah for a test fly tomorrow actually! Great forecast.
Our winter season of westerlies has begun.