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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Bob Johnson on May 21, 2014, 03:03:25 PM
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This thread is about my conversion of Be Bop Delux to electric power. As some folks may recall Be Bop was damaged at the Broken Arrow contest two years ago. The fuse was badly cracked at the wing joint and I judged it better (eaiser) to replace the fuse to save weight and retain strength.
About that time Brodak had their electric Super Clown system on sale so it seemed like a perfect time to get my feet wet.
I wanted to stay as close to the 36 oz. original model weight as possible and maintain good balance both horizontally and vertically. The problem was the bell crank is quite far forward in the wing and the flap horn gap is designed for a profile body. I didn’t want to cut into and modify the wing as it was fine as is. So… I set about to build a half build up fuse with profile tail. The photos will tell most of the story. In short I created a simple slab side box frame of 1/16 in. ply with a battery slot at about 40 degrees to place the battery weight as far back as possible and keep the vertical CG in reason. I used a padded brass battery stop that doubles as the instrument panel and a Velcro strap the secure the pack in the fuse. The box frame tapers back to the profile fuse just ahead of the trailing edge. Lightening holes are abundant to save weight and improve cooling. Most everything else is straight forward. I robbed the toy box for a He-man figure for a pilot head.
I’m very pleased with the outcome, though I would have appreciated a bit more explanation/direction about setting up the power system from Brodak. I was able to gather the info/guidance I needed for the posts on this forum. Thank you all for sharing your experiences.
The first flights were at the recent Fun Fly at Burlington, IA. At min. time and half power the lap times were 7 seconds. Steady flight even with the 10+mph wind. Flight two was min. time - full power and three was max time and max power on recharged battery, I did the hole pattern.
I have flown it once at home since then and I‘m very happy with the conversion, The system has no problem pulling the plane around and line tension is good throughout the pattern. The finished weight is 37oz., very close to the original when fueled and ready.
Very smooth and consistent. This could spoil ya.
I hope this might help someone else looking to get into electric C/L. I’m happy to answer any questions I can. Info below is also posted in setups thread.
Be Bop Delux - My own design( for O.S. .25) converted to electric.
Wing area - 430 sq in.
Weight - 37 oz. with battery
Prop - APC E 9x4.5
Brodak Electric Super Clown system
Motor - Arrowind 2815/09 1300kv
ESC - Arrowind 35a
Battery - Arrowind 3300mAH, 11.1 V 3s1p
Timer - Hubin FM-Oc
Set at max time & max power for now
Lines - 60 ‘eye to eye .015
Lap time – 5 to 5.1 sec
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I saw this airplane fly at Burlington and it has a very tight corner! Well done.
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Very nice Bob!! I hope to see it fly one of these days.
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GOOD WORK Bob! That power system also will drive an APC 10x5EP should you want to try a little more diameter...
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Kind of homely looking, but as long as it does its job.
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Man! Why didn't I think of that!
Mark
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Thank you Dennis for the prop suggestion. I think I might give that a try. I understand that the pusher prop helps line tension, correct? And Yes; Doc, I know she's not too pretty but this was a "get my feet wet with what I got" experiment. I'll "purddy up" the next one. ;)
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Bob
Yes, the pusher prop typically improves line tension over 45 degrees. Also removes any drama caused by torque on take-off. I'd suggest the APC 10x5EP, start it off at maybe 10,500 RPM and tune to suit.