mobert

I have just completed a successful electric conversion of a 40-size VMAR Chipmunk arf, using an AXI 4120/14 running on 14 GP3300 NiMh cells. On the first flight it leapt off the ground and surprised me with all the power! It weighs in at a hefty 6 and 3/4 pounds, which is a pretty high wing loading of 29 oz/sq.ft. Despite this, the motor provides excellent vertical performance for the first 5 or 6 minutes of flight. It cruises happily at just under half throttle. After some prop experimentation, an ASP 14x7 seemed to provide the best combination of power and performance. At lower-than-full throttle setting, the airplane tends to snap out at the top of an inside loop; entry at full throttle and full speed cures this. Although it doesn't snap at low speeds (surprising, given the high wing loading!), I am pretty much scared to slow it down on landing, but I'm not having any trouble sticking the landing.
I cannot really recommend the VMAR Chipmunk ARF, as it's built way too heavy and rather crude. That Polycote covering is very difficult to shrink, and seems to bubble every time it's out in the sun! The saving grace in this combo is the AXI - man, these are awesome motors! Way to go, Model Motors!
I am waiting for some Polyquest 2200 Lipo's which I will make up in a 4s2p combination. This will drop the weight by just over 15oz, and increase flight times by at least 3 or 4 minutes. The Chipmunk will be my "test bed" for this combo, and then will power a Kyosho 40-size Sukhoi SU-31 arf - now that's a beautifully built arf!