Balsa USA Stingray 120 Kit Build

earthsciteach

Moderator
Moderator
CONGRATULATIONS!!! She is beautiful in the air. Are you able to take the wing twist out? It looked like it flew very nicely, regardless. Well done, sir!
 

bicyclemonkey

Flying Derp
Mentor
I'm not going to bother trying to take the twist out. I'll end up making it worse. Once I finish sorting out all the details, I think it'll fly just fine. Right now it's nose heavy and I just remembered one wing came out heavier than the other so that may have had some to do with it also.

I swapped out the 18x10 for a 17x8 and the amp draw went down from 70 to 57 but the watts went from 1600 to 1300. 1300 is still 124W/lb so it should still fly nice. With the 18x10 I really didn't notice any extra speed above 2/3 throttle anyway.
 

bicyclemonkey

Flying Derp
Mentor
I added a receiver switch and LiFe rx battery as well as an 80a OPTO ESC. Although the new ESC was OPTO with no built in BEC, it was still way too hot after a four minute flight. The Cobra motor specs say to set the PWM to 8KHz (this was the default value for this ESC) and that it had 14 poles so I set the timing to the high/14 pole setting. I'll go ahead and mount the ESC to the front of the firewall below the motor with the heatsink facing forward...if this doesn't cool it off, I'm at a loss!

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I mounted the rx battery behind the CG to correct the nose heavy problem.

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bicyclemonkey

Flying Derp
Mentor
Getting the ESC mounted in front of the firewall. Got the ugly holes drilled.

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I had to notch the battery tray to make room for the zip ties and ESC throttle cable.

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Zipped in place.

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Throttle RX cable is routed underneath the battery tray.

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bicyclemonkey

Flying Derp
Mentor
That fixed it! The ESC was only 100 deg. after a four minute flight! The only problem now is that around 1/2 throttle the motor makes a squealing noise. It runs smooth before and after though. I'll upload a video ASAP, to see what you guys think. I'm thinking it must be an ESC setting. I don't recall the motor making any noise with the Turnigy Plush ESC.

Yep, The Turnigy Plush ESC didn't make any noise on the maiden flight or any of the other flights before I changed it out. I'm going to stick the plush in the front of the firewall and see how it behaves.

 

bicyclemonkey

Flying Derp
Mentor
The Cobra motor ended up having a bad bearing. I called innov8tive and they swapped it out for me. Absolutely no problems with the replacement motor. I got some aerial footage with my Mobius on the wingtip.