Here is a quick preview of my next frame for ArduCopterMega. That is my Tri-Copter frame with the old landing skids (t-rex 500) from first quad frame. I just need to rewire ECS :) And its ready to fly.
Arms are 15X15mm 1mm thick and 500mm long.
10X4.7 BC2836-11 750KV 30A ESC 4S 3000mah lipo.
Comments
And yes top/bottom speed ratio is there...
I believe it will be just another parameter in setup process :)
Max, more update on how the Y6 is flying, please! Will Y6 be implemented in the ACM Code when it goes beta?
And is it now possible to adjust the speed of the top ones compared to the bottom ones (either in the code in some other sort of gui, like the Mikrokopter does it?)
Regards
Daniel
@Gord
I saw these the other day...1100kv would be a bit fast because you would definitly want to run larger props with the added power, not to mention there is still a shortage of larger slow fly props out there. at least in the counter rotate side of life.. Also running three of these would be some serious power demand on a battery, since it calls for two 50a BEC's...they do have some 60-65C batteries out now that can handle this, however you are really looking at some weight at 298g a motor!! plus then figure the battery is something like 300-600g, so we are already at 1200-1500g with no propellers UAV board, FPV setup, or frame..so you would probly end up with something like 2200-2600g (rough estimate) flight weight, dont know the thrust these things can do but that would make a short flight time...Wouldnt mind seeing some more data on these though, for the wealthy AXI has a few countra rotating systems on their site.
"CR23L Contra Rotating BL System1100kv, our largest Contra rotating prop system yet, this is a monster!
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=..."
Little cheaper $31.
Zachariah, good thrust for a 100 grams weight, but in thrust/watt its 4.3g/watt at 3s.
My test with the BC2836-11 750Kv showed 1100g thrust at 19amps 3s, so that's 5g/watt. The results with 4s were slightly higher at ~6g/watt and the motors ran around 40F cooler.
Got to admit though there is something about the Y6 that really appealing.
@Gord
Thx. Understood.
@Zachariah
agree on "they don't act like a 4 blade prop because they counter rotate"
Yeah I keep going back in forth with the contra rotating system. your right it is a little expensive comparably speaking, however with the rotors so close I would imagine its a little more efficient, I would guess there is less turbulent prop wash with them that close. I wish I could find the video of a indepent test I saw with this to show you but at 1500g both motors were pulling 15amp which shows that both motors are pulling their weight, and they wight a little over 100g so seems like its a good system. I did find in one sights comments that someone ordered these for a quad, I should try to find it again and see if I can get some more info for the user and get in contact with him to see how they worked out for him.
I have also played with the idea to get some vario props, they are adjustable props (with a set screw) so you can adjust them in between flights to find the right pitch, the only problem I can see with those is well 6 props just a little off will cause an erratic flight.
The contra rotating system would work for a coaxial, they don't act like a 4 blade prop because they counter rotate, so there is no rotation force of a single prop just thrust, which is basically what your looking for a coaxial system. And since the motors are independently controlled changing the speed on one motor would cause a torque force to rotate the aircraft.
Zachariah, I think your correct. Even with 12x3.8 top and 12x8 bottom the lower motor was not fully loaded. Never flown with a variable pitch prop, but I'd guess that a (ex.) 10 knot headwind could be overcome with either increased rpm or pitch. Stumps me!
The "Contra Rotating BL System 375W" looks cool but expensive. You could buy a high efficiency MK motor for near the same price. I'm thinking that the contra rotating setup would act like a single 4 blade prop because there so close together, different than the coaxial that were discussing.
Here is a good page for some Y6 disccusions about props and prop speeds:
http://www.aplanding.com/forums/showthread.php?t=4993
Personally I am interested in trying these in my Y6
http://www.hobbyhot.com/aeo-model-1100kv-contra-rotating-brushless-...
or these if they are ever in stock
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...
1300g of thrust at 2*10 amps at 11 volts, good numbers, I saw a video where someone tested the 1st version of this motor that came with wooden props )instead of the plastic they use now) which produces 1500g thrust at 2x15 amp!! so for roughly 4500g of thrust on a y6, and something tells me you could more with better props and some very minor speed adjustments.
I have seem some impressive flight data from 12x4.5 top and 10x4.5 bottom, I forger the technical term but basically from what I read the props push down into basically a cone shape so that running the same size rotors on the bottom actually can decrease efficiency.
I have also seen some good numbers from somebody who increased the bottom rotor speeds by roughly 10%, but was still working on it.
Take the DragonFlyer x6 it uses 15" top rotors and 13" bottom rotors, and from starring at a lot of video it does look like the bottom rotors are spinning at a higher speed than the top, however I am not sure if this because they increased the lower motor throttles, an optical illusion caused by the props being a different size and counter rotating, or if there is a natural increase because the lower rotors are smaller. They do sell these props online for around $50 a set (top and bottom) however I cant find any info on pitch, or anything more on the motors they developed other than they run at 91.5 watts at 14 volts.
From what I see there is no differences in yaw from different sized props, or rpms or most control boards being used are compensating for this minor change if there is one.
If someone has the time I would like to see some figures from the 12x4.5 props on top and 10x4.5 on bottom then maybe try adjusting speed mixture up on bottom by 10% then 15% then by 20%.
Gord humor me but technically guessing, wouldnt running the 12X4.5 and the 12x8 basically be the same as running the bottom at twice the rpm with the same pitch? I think it be the equiviliant of running two 12x4.5 with the lower one running at like 88% faster than the top... Mind you I am guessing..
-
1
-
2
-
3
of 3 Next