Since I started flying r/c airplanes in the mid 70s when I was in high school I always wondered about the selection of propellers and glow engines for a particular airframe. After a long break from r/c, I built a couple of electric powered models in 2000. Neither model flew more than 20 feet off a hand launch until, after trial and error, I found correct combinations of propellers, gearboxes, motors and batteries. Not happy with the trial and error method, I wrote analysis software, measured the performance of propellers with diameters of 7" to 16" and compiled a database of performance data for electric motors, gearboxes, internal combustion (IC) glow engines and battery cells. This work has now evolved into a commercial venture as a service to assist UAV developers to identify the 'best' powertrain for their airframe. One measure of 'best' is maximum flight endurance. Please see our website: www.flightsolver.com For non-commercial users we can provide a limited service free of charge. So, if you would like some assistance or just discuss the topic of powertrain selection, please get in touch and we will suggest how we can help. All we ask in return is feedback on how we might improve our service. Contact: James Canova tel: 250 592 7027 cell 250 889 2834 email: jcanova@flightsolver.com (note: we are located in Victoria, British Columbia, Canada (just over the border from Seattle, Wash, USA)