Acro 280BB Motor w/ Direct 280
01-07-2003, 05:47 AM
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Acro 280BB Motor w/ Direct 280
In the quest for MORE POWER, I purchased an Acro280BB 6v motor, hoping to get the next level of performance out of Hobby Lobby's little flying wing, which, btw, has proven itself pretty much indestructable (so far). I'm running 720 & 800 mah, 7 cell packs with a WattAge IC-30 ESC.
The problem is that the motor cuts out at high throttle. It acts like it does when the battery is low and the BEC cuts in. Without running out and buying a nice, new multi-tester, I think that this motor is within the rating of the ESC (30a continuous/40a surge). Is it a BEC thing, in that the voltage is dropping below the BEC cutoff of, what, 4.8 volts? Would an extra cell solve the problem? Although I may not modify the Direct280 to take 8 cells, I can keep the motor for the next project.
Also, on it's maiden flight with the new motor, the motor mount didn't exactly match the new endbell and the subsequent change in thrust angle (damn!, it looked pretty close) made for a wild ride that cost the Direct280 one of its 9 lives and the motor one of its motor-lead tabs. The plane survived and a little AE in the form of a piece of copper braid hardened with solder, replaced the motor tab, so I'm back to the motor cut-out problem.
Any ideas?
TIA
SavoirFaire
The problem is that the motor cuts out at high throttle. It acts like it does when the battery is low and the BEC cuts in. Without running out and buying a nice, new multi-tester, I think that this motor is within the rating of the ESC (30a continuous/40a surge). Is it a BEC thing, in that the voltage is dropping below the BEC cutoff of, what, 4.8 volts? Would an extra cell solve the problem? Although I may not modify the Direct280 to take 8 cells, I can keep the motor for the next project.
Also, on it's maiden flight with the new motor, the motor mount didn't exactly match the new endbell and the subsequent change in thrust angle (damn!, it looked pretty close) made for a wild ride that cost the Direct280 one of its 9 lives and the motor one of its motor-lead tabs. The plane survived and a little AE in the form of a piece of copper braid hardened with solder, replaced the motor tab, so I'm back to the motor cut-out problem.
Any ideas?
TIA
SavoirFaire
01-13-2003, 07:26 PM
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Acro 280BB Motor w/ Direct 280
Maybe the increased current draw of the hot 280 is loading the batteries to the point that the voltage is decreasing to the cutoff point at max speed.
If you can fly around at 75% throttle with no problem, I would look in that direction. Just put a voltmeter on you battery wires and see what happens to the voltage as you open the throttle. If you have long leads between battery and esc, and connectors, that could be another point of voltage drop.
If you use a hotter motor, the power has to come from somewhere... you stayed with the orig 7 cells, so the extra power is coming from more current draw... and the resulting voltage drop is realized from battery internal resistance, wire ir-loss, contact resistance in connectors.
Check to see if the ESC is rated for the increased current draw of the new motor. If that new 280 is a high rpm (Kv) motor, it might take a higher gear ratio to realize a usefull increase in power to the prop.
Just my opinion, your mileage may vary.
Emil
W9NM
If you can fly around at 75% throttle with no problem, I would look in that direction. Just put a voltmeter on you battery wires and see what happens to the voltage as you open the throttle. If you have long leads between battery and esc, and connectors, that could be another point of voltage drop.
If you use a hotter motor, the power has to come from somewhere... you stayed with the orig 7 cells, so the extra power is coming from more current draw... and the resulting voltage drop is realized from battery internal resistance, wire ir-loss, contact resistance in connectors.
Check to see if the ESC is rated for the increased current draw of the new motor. If that new 280 is a high rpm (Kv) motor, it might take a higher gear ratio to realize a usefull increase in power to the prop.
Just my opinion, your mileage may vary.
Emil
W9NM
01-30-2003, 06:17 AM
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Acro 280BB Motor w/ Direct 280
OK, I solved the problem with a little help from the guys at Hobby People. The stock prop was a Gunther 4 x 4.75....the same one used on the Zagi 400. I switched to a prop from WattAge's J3 Cub which runs @ 3 x 2. I just popped off the cute yellow spinner and jammed it on backwards (pusher). No problem with cutting out now! The RPMs are about double and thrust is off the charts....it sounds like a ducted fan. Vertical performance is great, rolls are too fast to count and if history is any indication, I'm sure I'll wind up drilling it in soon.
Maybe a similar fix will help some of you guys with the Split 280, although I think that the Direct 280's thicker wing section is the only thing that kept the wing from folding. Lower rates should help that.
Savoir Faire
Maybe a similar fix will help some of you guys with the Split 280, although I think that the Direct 280's thicker wing section is the only thing that kept the wing from folding. Lower rates should help that.
Savoir Faire
