Foamy power ?? No one on any forum will respond !! Please !!

[scubas00755511]

I have a Charger flat out bi plane with a typhoon 15/10 mico brushless, 12v, 1500kv motor, 3cell 1500 12c cheap no brand lipo, 11x3.8 size prop. It flew great in the warm desert. But when I went to 40 degree, 7000ft elivation, I puffed 2 lipo's in less than 5 min flight time. do I need a different size prop or need to change the pitch on the prop?? And whats an affordibe lipo brand, and what size/discharge rate lipo should I get ? Thank you.. :dontknow Its my little brothers plane he is bumed out, and im a heli man, so I dont know.

[UFO8MyCow]

try a prop with more pitch

[WayneBrown]

You actually need to go down is size and pitch. Cooler air is denser, and will load the prop more resulting in increased Amp draw.
I used the TP 1350's with good results after trying nearly everything else. The higher C rating, the more Amps you can draw, IF you had a 20C battery, You'd most likely still be using the packs now.

[kgfly]

Well given you moved to 7000ft, I disagree with Wayne's analysis.

At the same temperature the air is about 23% less dense at 7000ft vs sea-level. Assuming the temperature went from 80F to 40F it is still about 18% less dense at 7000ft than sea level.

Less dense air makes both the prop and the wing less efficient, requiring more power from the motor to perform at the same level. My guess is that you simply used more throttle than you ever had to before and this is what toasted your batteries. So higher C rating is definitely in order. Larger capacity batteries might be needed to achieve the same flight times at high altitude. I have been happy with my cheap hextronik batteries from unitedhobbies.com but others have not.

I don't know enough to advise whether you should go up or down in prop diameter or pitch. Try the wattflyer forum, I bet you will get an answer there. Post back to this thread with the outcome.

[Funflyer]

I use the TP 3s 1350 Prolites on my planes. I haven't ever had any trouble out of them.

[scubas00755511]

I need a prop size recomendation for my problem !!

[WayneBrown]

MSL to 7000 ft, estimate a 40* temperature change(80F desert, 40*F @ 7000ft), I'd say at best the air density is a wash to slightly more dense.
There are also other contributing factors, such as ambient barometric pressure and humidity levels, but even giving them a passing thought you end up with denser air.
Try going down in size and pitch. If you are at 4.8 Pitch, go the next inch smaller diameter.

[scubas00755511]

Ive got a few mixed oppinions so, Ill try a TP 1350 20c lipo, and a few smaller props w less pitch and a few bigger props w more pitch. I have to send them to my little bro, and will post the test results next weak due to shipping time. Where do you shop online?

[scubas00755511]

Smaller prop w more pitch, Fully max 3cell 20c lipo gave the power back..My little bro is back in the air... :mrgreen: Now he just need to learn to land in the thin air, powerd down drops like a rock, take alot of air speed to set her down. Maybe a single wing instead of a bi plane ?

[kgfly]

Interesting, thanks for closing the loop on this one.

[flying 442]

Did you also make the move? If so was there anything you had to do to your heli? Pitch curve, more throttle? Just wondering, Jon

[scubas00755511]

What movie?

[SonGunnar]

Scuby,

These guys are flying at 7 and 8K ft. and have prop suggestions. Slower planes but they found that smaller direct drive props worked better in high altitude.

Prop recomendations for their Scratch builds below.

http://www.rcgroups.com/forums/showthread.php?t=338359&highlight=colorado+epp Search within forum to Colorado and EPP :mrgreen: