Thread: Discussion FlySky/Turnigy 9X Protocol
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Old Feb 23, 2013, 03:25 AM
ThierryRC is offline
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France, Alsace, Strasbourg
Joined Dec 2012
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I think a tri copter is easier to do because you only have 3 motors/ pwm (pic18f14k22 has allready 3 pwm outputs, so easier to program) and mixing is also simplified because yaw control and individual motor speed control are not really linked.
Yes, with a mini quad copter board you can do an octocopter with motors in parallel (btw this way, you can do copters with 12, 16, ...4xN motors) just like Dave has done but you cannot do counter rotating propeller octocopter because individual motor control is different and I think better than a quad:
with a quad to turn (yaw axis) you slow motors diametrically opposite, and accelerate the other ones... if you do quick and rapid turns you'll notice sometimes an oscillation on pitch/roll axis and I think it is related to the fact that 2 motors are really slow to have good control...
In a contra propeller configuration you just slow upper motors and accelerate the others (or vice-versa) so this can't happen.
What's more studdies and tests have shown that a contra propeller configuration is 5% to 15% more efficient than 2 separate propellers at same speed.
However with turboprop engines mechanical parts (gears) are complicated and does not last long, that's why you will rarely see that (russian have done pretty good planes however), but with independant electric motors we don't have these drawbacks
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