If you have never built a thermal ship from scratch and never intend to, read no further.
After posting a new thread about the Spirit for sale I thought to bring to your attention another subject that would suit the occasional park thermal flyers amongst you.
If you are ever looking for a small to medium size glider and you are also keen to build something, you should at least consider the Allegro-lite. This a high performance design by MIT aerodynamics Professor, Dr Mark Drela.
Why is the Allegro-lite considered high performance ? with an all up weight of 19 oz for a two metre glider and sporting the AG series profile you are guaranteed two things: a) superior response to the lightest thermals and b) incredible penetration for such a light model.
The home made carbon spar system means a strong wing that can withstand strong hi-start and winch launches.
There is nothing about this design that should prove difficult to construct for the average builder.
If 2 metres is not your thing then consider its bigger brother, the Bubble Dancer at 3 metres.
Dr Drela's airfoil sections are much thinner than we are used to with your Clark Y's, Selig and Eppler sections. This means faster speed when cruising between thermals into wind. The unique carbon spar design means the much needed strength can be built into this relatively thin wing and at the same time maintaining an extremely light wing loading.
I built my Allegro-lite a few years ago and am always blown away with the performance. I built a 3.6 metre version of the Bubble Dancer 3m, because I wanted the same incredible performance in a bigger ship that could be easily seen above 2000 ft. Something which these ships get to every time there is lift available.
The Allegro-lite is a Rudder/Elevator/Spoiler (RES) polyhedral design wing of built up balsa construction which breaks down into three pieces for ease of transport. The all moving tailplane sits on top of a carbon 'V' strut making it also removable for transportation. This carbon 'V' strut being the only component which is a little tricky to do from scratch. ( I might be persuaded to fabricate these for anyone who wants to build the model)
The AMT can however be built as a fixed stabiliser with elevator if desired, negating the need for the carbon 'V' strut, which is easier with only a little compromise in performance.
The huge spoiler is very effective and although not absolutely necessary is a good idea because this model wants so badly to go UP ! and keep going up, that it can sometimes be difficult to bring down.
Plans for the Allegro-lite and the Bubble Dancer can be downloaded FREE fromhttp://www.charlesriverrc.org/articles/ ... lite2m.htm
However if you don't like the idea of joining up a bunch of A4 printed sheets, I can provide a complete plan for either ship.
You simply can't go past these ships for performance, I've owned nothing but thermal and slope ships for 25 yrs and these`are the best built up thermal soarers I've come across.