View Full Version : Sterling .25 size corsair to electric

07-22-2005, 03:42 AM
Hello, thought I would share my experiences with this project and maybe get some input on it . I bought a built Sterling Corsair and have had it hanging in my sons room for a few years. I decided to try to make it an electric powered plane. It was never flown, never had an engine installed and never had control rods or servos etc. installed. I pur a geared Astro Cobalt 05, with a 4200 mAh battery in it. It weighs just under 3 pounds, I will change out the rubber tires for some foam ones to save a little weight. This seems to be a bit on the heavy side for a plane with a 36 inch wingspan. I put a fishing weight scale on the tail and at full power it pulls approx, 1.25 lbs. I am fairly new at this and figure it has enugh power to take off and fly, but landing may be very challenging. Any thoughts?

Matt Kirsch
07-25-2005, 08:18 PM
What's the configuration of the "4200mAh battery?" How many in series?

1.25 pounds of thrust on a ~3lb plane... It'll fly, but I don't think it will be any fun to fly. You are probably underutilizing the motor, though.

07-25-2005, 10:36 PM
Hello Matt, Thanks for your response. The battery is a 3cell2p. It did not do well on its first flight. I had a guy at my flying field experienced in flying warbirds take it for its first flight. It gained speed quickly and was pulled into the air after a run of about 50 feet, it rose reluctantly about 2 feet off the ground before it started a back and forth roll, went inverted and hit upside down. It just didnt seem to have enough speed. Luckily the most damage was to the prop.
I am not sure if I should try again with a different pitch prop, but If it was barely flying at that speed, landing will be tough, trying to keep it from stalling. What did you mean by underutilizing the motor? I like the idea of electric flight, and would like to find a warbird to use this motor/battery combo on. I probably need a plane with a larger wing and less wing loading. Any idea what a good use for this motor would be? Any suggestions would be greatly appreciated.
Thanks, Denny

Matt Kirsch
07-26-2005, 03:07 AM
Trust your instincts here. The plane definitely didn't have enough speed to fly, and not enough power to pull it through. A little wing rock, a tip stall, then over she goes and splat...

By underutilizing the motor, I mean the motor is probably capable of handling much more power than you're putting through it. What size prop are you running?

The motor/battery combo you've got would be decent in a .25-size trainer or other sport plane in that size range. It's a little heavy, so look for planes with large wing areas.

08-04-2005, 10:19 PM
Hi Matt, got the crashed computer up and running agasin. the prop was an 11X7 I think I should have had a 12 X 8.

08-26-2005, 09:49 PM
I have the same old Sterling kit. I think that it was designed for a Tee Dee .049 or 099 and lightweight R/C gear. Your conversion probably weighs more and your plane probably needs another cell to fly fast-enough to avoid tip stalls etc on take-off. Your thrust should be about 70% of the weight of the model. The similar size but much lighter GWS and Alpha WWII foamies fly nicely on the GWS 300C 370 motor/geardrive and 7-cell NiMh packs but even better on brushless replacement motors and 3 cell Lipo packs. Let us know if you get your Corsair flying well with your setup or changes.