‘Thermolite’ Slope Soarer (with a…)

Following on from the ‘Flying Brick’ lessons learned which is ready for the right conditions i.e. lots of lift… I had a rethink on my second prototype requiring it to be significantly lighter and have a motor fitted (hidden when soaring) to enable it to be flown at the field assuming it does fly.

The key differences to try and meet the lighter weight is; a carbon fibre boom and moving tail as the back end of the Flying Brick is the primary contributor to the overall weight as the balance weight had a ratio of 2.8:1.

To improve the build finish and help keep the weight the wing skins are made as two separate pieces using aluminium moulds then bonded together with spares glued in. The fuselage mould is mage from 2” aluminium tube; shaped then split on the vertical axis.

I have attached a couple of initial photographs; one of the moulds and the other of the part assembled components. I will be providing updates as I get a little further through the build.


2014-12-19 17.11.33


We are now getting closer to painting, need to fit the wing servos and tips… The controls for the moving tail and rudder are complete ready to fit after spraying, but what colour(s) shall I use?

Thermolite nearly ready to paint

The final painting and assembly is complete with an ready to fly weight of 1.4kg a touch heavier than wanted and may push the motor to the limit when field flying, that’s assuming it flies… I used base coat metallic silver as it thin and should be lighter that standard gloss cellulose.

Pre maiden flight
Pre maiden flight

Assuming it flies at the field and is not destroyed, the next step will be to replace the prop spinner with  a glass fibre nose for soaring.

5 thoughts on “‘Thermolite’ Slope Soarer (with a…)”

  1. GOOD NEWS; the Thermolite flies. On the maiden it was rolling to the left a little, landed it on the patch (which is good for me!!!) and it turned out to be the flaps which were not completely level, 1 up and 1 down slightly. As expected the motor was a little underpowered but checked when I got home and it was only drawing 120w, so bigger props to be ordered…

    On the second flight it flew much better with the flaps realigned but found that it does need a good turn of speed and will not be a particularly good thermal glider for the field…roll on the slopes…

    The plan now is to mould a nose cone for the slopes to completely hide any trace of the motor (for Robert)

    1. Barry
      I think this is interesting.
      It comes from this thread.


      Since it is an adjustable tow hook, you don’t even have to worry about where it goes as long as you are more or less centered on the CG. That is precisely due to the fact that your cg, and your tow hook location are not actually related. Whereever you put your tow hook becomes the CG during a launch. In other words, even if your tow hook is one inch behind the CG (Say you balanced your Supra at 90mm from the LE, and the suggested location is around 104mm) If you mounted the tow hook at 104, as long as that is not behind the wings center of pressure, you will get a nice clean stable launch. The tow hook location is the CG during launch. Also, true would be if you had an unflyable CG due to all of your nose weight falling out, your launch would still go fine while under tension. As soon as tension is relaxed or released you would have an unflyable or way tail heavy glider on your hands.

      So, use the suggested CG as a guide, center your hook box on that point, install, fly, and adjust. Nothing to it.

      Good luck