Electric Stunt > Gettin all AMP'ed up!
Electrocuting the Atlantis
Tim Wescott:
Finally decided to pull the trigger on going electric. I'm starting with el-cheapo batteries and a Cobra motor (inexpensive, but some folks seem to like it). I have an old Shultze ESC that was given to me, and should work, and, of course, I'm friends with the wife of a guy who makes timers.
Comments from the peanut gallery on how to mount that motor are welcome. If it was all fresh dry wood I'd put a ring mount in the front, and front-mount the motor -- unless someone speaks up and tells me that Cobras don't like that. Part of me wants to machine a mount that'll catch the existing motor mounts and rear-mount the motor. That'll both give me something that's drop-in, and it'll be drop-out in the event that I decide I hate electrics after all.
Hopefully I've done my math/guessing right. For reference the plane is around 690 squares, and weighed 64 ounces empty with a 46LA. The starting setup is:
Cobra 2826-12 motor
Turnigy 3300mAh 5S battery (I got one 3300mAh and one 3000mAh, to figure out which is best)
Shultze ESC: fut-18.46K-F2B.gra (mit F2B Programm, es müssen kuhl sein!)
Some TUT or other.
I'll want to make room for a Recording TUT, even if I don't have the @#$% recording part working yet. I'll probably use Howard's AMA program, to go with the Shultze's F2B governing mode. Should have quite Hubin-esque flight characteristics, except for the Rushian slow take off.
I'm not sure what prop to use to start -- I'm thinking a 12-6, although the very first run may be a 12-6 cut down to 11-6, for ground clearance. Suggestions welcome...
The ESC has no BEC, so I'll have to tuck a voltage regulator in there somewhere. The TUT draws little enough current that I can probably get by with a 78L05 in some heat shrink.
Look at all the room in that equipment bay! Those things always look so sparse before you try to jam the last little bit-o-kit in there. Like the ESC. And the timer. And all the wires. Omigod, I'm doomed.
Howard Rush:
Glad to hear you are going electrical. K2R spot remover (probably Cab-o-sil and a solvent) is good for sopping up oil.
People have had more success mounting the Cobra on the same side of the motor as the prop than on the opposite side from the prop ("front" and "back" definitions may vary).
I have some extra props. The APC is cheap and good, but you'll probably want one that goes the same way as your old engine.
Tim Wescott:
--- Quote from: Howard Rush on July 25, 2019, 10:56:58 PM ---I have some extra props. The APC is cheap and good, but you'll probably want one that goes the same way as your old engine.
--- End quote ---
I got "tractor" props. More props to experiment with would be good.
Should I stick with 12" and lengthen my landing gear, or is it even remotely sensible to hold the diameter to 11"?
Crist Rigotti:
How much do you figure will be the final weight? Depending on the weight, I think you have too much battery. I'm flying on a 5S 2450mah battery with a weight of 52 ounces. I'm using @ 75% of the battery.
Tim Wescott:
--- Quote from: Crist Rigotti on July 26, 2019, 07:19:07 AM ---How much do you figure will be the final weight? Depending on the weight, I think you have too much battery. I'm flying on a 5S 2450mah battery with a weight of 52 ounces. I'm using @ 75% of the battery.
--- End quote ---
It's 64 ounces with the 46LA and all the slimer equipment. I'm assuming it'll be the same or slightly more with electrons.
If I just scale your figures by weight I get 3000mAh -- and that's what I would have bought across the board except that I chickened out and got a 3300mAh to try the first time, on the theory that an overweight plane in testing is better than a nice light pile of balsa trash after pooping out at the end of the pattern.
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