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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Dennis Adamisin on October 30, 2009, 02:56:14 PM
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This morning I finished a 1/2A size Brodak Twin Mustang converted to ECL In a fit of "ECL Evangelism" I posted it over in the 1/2a forum. Fun project so far, and am looking forward to test flights - just cuz its so cool!
The power system is two of the new Brodak 1/2A power systems that are due in by the end of the month. Same system I had on the Baby CLown at the Fly-In back in June. Set-up to run on two ESC's but one batttery & Timer.
Question for the ECL group - especially those of you with TWIN experience: What shall I expect the power usage to be?
More Background: The timer is hard-wired for full throttle operation for 3 minutes - no adjustments. On the Baby Clown it uses 320 mah turning a 6x5.5 prop. The F-82 uses a similar wing to the BC but stretched with tapered outer panels. THe BC weighs about 8.5 oz, the F-82 wieghs 12 oz.
If everything else were equal I would expect the load on each motor to be LESS than it is on the Baby Clown, so current draw on each motor will be less than 320mah. I would not expect the twin to fly much faster, but I'll bet it NEVER slows down! in total I expect that the current used will mostly reflect two sets of motor eficiency losses - maybe plus a little, but that the total current draw will be much less than simply doubling the current used by the single.
Experience or opinions anyone???
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Not twin
engine motors, but how about twin 6-4 props?
With this I got a pretty good pull, and used some 310mAHr from my 2s730 pack. With a single 6-5.5 I pulled ~240 mAHr.
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Hi Dennis,
I'm dying to find out.
Are the two motors running in opposite directions?
Dean
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Hi Dennis,
I'm dying to find out.
Are the two motors running in opposite directions?
Dean
I hope so---since he is using one pusher and one tractor! <= (that may have been on the other thread in the 1/2A forum)
Now I was using two tractors on the one motor, maybe I should have tried a tractor and a pusher, just to see which way the model moves!
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Hi Dennis,
I'm dying to find out.
Are the two motors running in opposite directions?
Dean
But of course! y1 #^ 8)
Did a little reasearch, discovered the full siae proto was built with the RH engine on the left side, LH on the right. The proto would NOT leave the ground. After some head scratching they figured it was due to downwash on the center wing panel, so they swapped the engines side to side and the rest is history...
I of course duplicated the full size. Actually the reason I am using 6x4's is that they are available in opposite rotation, would have prefered to use 6x5.5's as I do on the Baby Clown.
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On the other hand Dennis if you use both props as tractor and make one motor run in reverse it might outdo a bislob for interesting moves! LL~
bob branch
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Hi Dennis - I have flown two twins over the last 3 years. To estimate how much
each motor would draw, I built a simple mock-up to run tests as well as develop
the wiring lengths. You are right in assuming that two motors do not draw as much
as double one motor. In my case this may have been influenced by the battery
performance. I was using one TP14.8v 4000 mah battery one timer and 2 ESCs.
I also found that you may not get the same RPM from each motor. It depends on the ESC match up. I finally found the right match after trying 4 cc35s in an attempt to get the same RPM. My motors and props were larger than yours but, I think these are things that you will find the same or similar.
Sincerely, Walt Brownell
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Dennis - There is one thing about twins I forgot to mention in my previous
post. Depending on what type ESCs you use, you may need to only use one
BEC and disconnect the other. I think this is only true on the switching type
ESCs.I found this out when I bought a Jeti. It may also be true for the CC ICE
ESCs.
Walt Brownell
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Dennis - There is one thing about twins I forgot to mention in my previous
post. Depending on what type ESCs you use, you may need to only use one
BEC and disconnect the other. I think this is only true on the switching type
ESCs.I found this out when I bought a Jeti. It may also be true for the CC ICE
ESCs.
Walt Brownell
DUNNIT! y1 Thanks for info.
Was warned about that by Will Hubin. On the "Y" harness I clipped the positive lead from one of the sockets, kept the signal and ground...