The Towner plan of the Short Stirling is available from a couple of sources. In the UK there is Pete's Plans in Cardiff, Wales (peter.williams@btinternet.com) or alternatively there is Bob Holman plans in the US (
www.bhplans.com). Bob doesn't have the Towner plans listed but they are available.
I have a number of Towner plans including the Short Stirling, which could easily be modified for electric motors and radio control if desired.
Hope this helps. If you have any further questions don't hesitate to send me an email.
Regards
Paul (g-fiend)