An Electric Competition Model.
The advent of inexpensive brushless motors, controllers and high energy density LiPo batteries has opened the flood gates in system design for electric free flight competition. This is an attempt to produce a 'Proof of Concept' lightweight electric model for light air, using inexpensive components and avoiding the knock on effect of massively high power motors. The HTL (High Thrust Line) layout is a favourite of mine, the 4th in the series and easier to trim, in my opinion, than a conventional pylon layout. The thrust line is higher than the CoG giving a nose down pitching moment for incremental power increases. Hence the looping tendency of the HTL layout tends to be less sensitive than the pylon layout.
The specification is ..
Thrusts of 300gm and energy densities of 350Watts/kg are possible and planned, with minor revisions to motor and battery, providing one can successfully manage this power increase .time will tell.
Trimming methodology is to start with low power for a 20s run and gradually increase, noting the change in flight pattern and taking the appropriate action to avoid disaster. This is contrary to SLOP and F1C practice and makes for a lengthy trimming period but so far I have not totalled an airframe and would never risk an untrimmed model at full chat even for 5s. I am happy with this method, however unconventional and would recommend it for the novice.
Ian Middlemiss - September 2010