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Y4 layout


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#21 joecnc2006

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Posted 13 July 2011 - 01:49 AM

Can you post screen captures of your mixing settings.
Thanks,
Joe
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#22 Mat Wellington

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Posted 13 July 2011 - 04:16 AM

no problem

motor 1 left front, motor 2 right front

motor 3 right rear CCW
Motor 4 left rear CW

10" props front, 8" back, identical motors, CG/CL at 1/3 distance from front to rear

Attached File  KRC_Vtail.jpg   75.48KB   317 downloads

#23 Aerhead

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Posted 13 July 2011 - 04:58 AM

Mat

The UAVX has firmware for V tail Y4 quads. I tested v tail configuration on a bench stand and found that you lose a lot of lift if you have the prop wash intersect. Even having two 10" props one inch apart is over 5% less efficient than have the props 4" apart.

Larry


no problem

motor 1 left front, motor 2 right front

motor 3 right rear CCW
Motor 4 left rear CW

10" props front, 8" back, identical motors, CG/CL at 1/3 distance from front to rear

Attached File  KRC_Vtail.jpg   75.48KB   317 downloads



#24 Mat Wellington

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Posted 13 July 2011 - 06:53 AM

Mat

The UAVX has firmware for V tail Y4 quads. I tested v tail configuration on a bench stand and found that you lose a lot of lift if you have the prop wash intersect. Even having two 10" props one inch apart is over 5% less efficient than have the props 4" apart.

Larry


Hi Larry, yep understand that.

All the Y shapes are compromised

If i space the rear motors apart to 4" seperation, then its a quad, if i go to half that, i suspect i will start seeing roll induced from the yaw

I already loose 25% or so due to the angled motors, so another 5% gets me to 30% total ineficiency from the rear set,
averaged over the front two and rear set, its about 10% per corner

A tri copter loses up to 25% as the rear motor rotates

A Y6 is already 15% in the hole due to coaxial losses.

The payoff tho, in this case is something with the gracefull flying of a tri, without the complexity of the rear yaw

Next stage of development will be some much larger motors on the front (with the subsequent shifting forward of the CG/CL) and the over all ineficiency will drop to below 10%

#25 Aerhead

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Posted 13 July 2011 - 11:57 AM

Mat

The point I was making is if you angle the V tail motors the opposite direction you get a little higher yaw authority and less then 10% loss of lift over a quad. If you have the V tail motors on top of the props it's easy to build.

Cosine(30 degrees) = 0.866025404 is the thrust so 13.4% would be the reduction due to the V angle. You gain 5% for not having the prop blast close together like many quads are setup. I know it doesn't seem right but this means you only lose 8.4% over a quad that has the props only 1" apart.

Larry

Edited by Aerhead, 13 July 2011 - 12:05 PM.


#26 joecnc2006

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Posted 13 July 2011 - 12:13 PM

Mat

The point I was making is if you angle the V tail motors the opposite direction you get a little higher yaw authority and less then 10% loss of lift over a quad. If you have the V tail motors on top of the props it's easy to build.

Cosine(30 degrees) = 0.866025404 is the thrust so 13.4% would be the reduction due to the V angle. You gain 5% for not having the prop blast close together like many quads are setup. I know it doesn't seem right but this means you only lose 8.4% over a quad that has the props only 1" apart.

Larry


Are you referring to how he originally had the props pointed inward, or how he has them now, which is pointed outward as he stated he changed it this way when I mentioned he test it after his original inward prop wash crossing. And after he changed it he mentioned he has much better yaw authority.
Thanks,
Joe
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#27 Aerhead

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Posted 13 July 2011 - 03:45 PM

Joe

Thank you I guess I missed that part. I've tested the vertical thrust you get with 30 degree off vertical tilt and I is very close to what the math says it should be.

Larry

Are you referring to how he originally had the props pointed inward, or how he has them now, which is pointed outward as he stated he changed it this way when I mentioned he test it after his original inward prop wash crossing. And after he changed it he mentioned he has much better yaw authority.



#28 Mat Wellington

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Posted 13 July 2011 - 05:39 PM

Mat

The point I was making is if you angle the V tail motors the opposite direction you get a little higher yaw authority and less then 10% loss of lift over a quad. If you have the V tail motors on top of the props it's easy to build.

Cosine(30 degrees) = 0.866025404 is the thrust so 13.4% would be the reduction due to the V angle. You gain 5% for not having the prop blast close together like many quads are setup. I know it doesn't seem right but this means you only lose 8.4% over a quad that has the props only 1" apart.

Larry


Hi Larry, just so i understand, in the below photo,is this the better way to have it ?
Attached File  SAM_0107.JPG   350.09KB   256 downloads
Thanks for the above numbers, its good to know that the losses arnt as high as i guestimated :)

#29 jes1111

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Posted 13 July 2011 - 10:00 PM

Mat, this is fascinating! Thank you for doing all this: you're advancing the frontiers of mankind's knowledge (well, the OP team's, at least). ;)

I have another layout to try if you're up for it! Y3, like a tricopter, but instead of tilting the rear motor you place a rudder vane in the prop wash. The rear motor may or may not be slightly angled to balance the torque at hover (otherwise the neutral position would be with the rudder applying slight correction). Seems to me it would be mechanically simpler than tilting the motor and might be less "lossy" than a tricopter tail. Of course, the same trick could work with a Y6 and also as a way of boosting yaw authority for very large frames.
Jeremy

#30 Aerhead

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Posted 14 July 2011 - 12:49 AM

Mat

Yes, your copter now has no commingling of prop wash. The V tail propellers could be less then an inch apart and still run at top efficiency.
Of course I also have an idea for your next modified build. The idea is to build a craft that can fly like a dual rotor gyrocopter. All you need is a servo that would angle the V tail motor set or a single motor with Less's fin, to the rear to produce forward thrust. As you tilt the tail you would also pitch the craft up. The two front motors should slow and act as powered gyrocopter rotors while the V tail motor are running at high speed to push the copter forward. My guess is you will be able to fly longer than a normal setup. The farther forward the center of gravity the greater the efficiency should be and the further you could tilt the tail to the rear. Now add a VPP to the rear motor and make sure that the front two motors turn CW on the left and CCW on the right and you have a model for the fastest helicopter ever built. The front propellers have to have the outer blades moving forward to maintain roll authority as the copter increases it's speed. I don't know but maybe there is a reason no buddy has tried this setup. Tuning could be very difficult.

Larry



Hi Larry, just so i understand, in the below photo,is this the better way to have it ?
Attached File  SAM_0107.JPG   350.09KB   256 downloads
Thanks for the above numbers, its good to know that the losses arnt as high as i guestimated :)



#31 Mat Wellington

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Posted 14 July 2011 - 09:06 AM

Mat, this is fascinating! Thank you for doing all this: you're advancing the frontiers of mankind's knowledge (well, the OP team's, at least). ;)

I have another layout to try if you're up for it! Y3, like a tricopter, but instead of tilting the rear motor you place a rudder vane in the prop wash. The rear motor may or may not be slightly angled to balance the torque at hover (otherwise the neutral position would be with the rudder applying slight correction). Seems to me it would be mechanically simpler than tilting the motor and might be less "lossy" than a tricopter tail. Of course, the same trick could work with a Y6 and also as a way of boosting yaw authority for very large frames.


I saw a project on RCG for exactly that, it wasnt too sucessfull

#32 Mat Wellington

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Posted 14 July 2011 - 09:10 AM

Mat

Yes, your copter now has no commingling of prop wash. The V tail propellers could be less then an inch apart and still run at top efficiency.
Of course I also have an idea for your next modified build. The idea is to build a craft that can fly like a dual rotor gyrocopter. All you need is a servo that would angle the V tail motor set or a single motor with Less's fin, to the rear to produce forward thrust. As you tilt the tail you would also pitch the craft up. The two front motors should slow and act as powered gyrocopter rotors while the V tail motor are running at high speed to push the copter forward. My guess is you will be able to fly longer than a normal setup. The farther forward the center of gravity the greater the efficiency should be and the further you could tilt the tail to the rear. Now add a VPP to the rear motor and make sure that the front two motors turn CW on the left and CCW on the right and you have a model for the fastest helicopter ever built. The front propellers have to have the outer blades moving forward to maintain roll authority as the copter increases it's speed. I don't know but maybe there is a reason no buddy has tried this setup. Tuning could be very difficult.

Larry


Sounds like a cool project - but not for me at this stage.

a simpler system may be to have a tri or quad setup, with a EDF to provide the forward thrust.

However, i feel it may act like a pizza box flyer and get super pitch sensitive, a saving grace may be to do it as an extended tricopter, with a large tail moment to dampen the pitchiness

#33 Maxrr

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Posted 14 July 2011 - 11:13 AM

However, i feel it may act like a pizza box flyer and get super pitch sensitive, a saving grace may be to do it as an extended tricopter, with a large tail moment to dampen the pitchiness

I think you might be right about the pitch sensitivity, fixed pitch props can get very pitchy when flying sideways through the air. Normal heli blades are much better but you may as well just make a heli modified for speed if your going to lose the mechanical simplicity of a multicopter.
It's fun to dream up these hybrid designs anywayPosted Image. I've been thinking of a quad with a small amount of thrust vectoring lately myself.
It would be cool to be able to move about slowly without pitching the quad. Finding a tilt mechanism for all four props that's simple is the trick!




#34 Aerhead

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Posted 14 July 2011 - 12:25 PM

Max

I'm glad to see there is a good grasp of the difficulties involved here. To me the interesting part would to try to gain longer endurance with forward flight.

I plan to try building an octocopter that will fly while staying level. I'll build it this winter using two CC FC. One would be in + mode and control four motors that are pitch at least 30 degrees toward the center. The other FC would be in X mode controlling four motors pitch out from the center of the octo. The efficiency lost is most likely less then the losses caused by the added weight of motor tilt mounts and servos. Controlling two CC FC can be done with two RC Tx/RX or maybe a 8 or more channel mixing Tx/Rx would work. If you pitch the motors 45 degrees you only lose less then 30% lift.

Larry



I think you might be right about the pitch sensitivity, fixed pitch props can get very pitchy when flying sideways through the air. Normal heli blades are much better but you may as well just make a heli modified for speed if your going to lose the mechanical simplicity of a multicopter.
It's fun to dream up these hybrid designs anywayPosted Image. I've been thinking of a quad with a small amount of thrust vectoring lately myself.
It would be cool to be able to move about slowly without pitching the quad. Finding a tilt mechanism for all four props that's simple is the trick!


Edited by Aerhead, 15 July 2011 - 12:07 AM.


#35 jes1111

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Posted 14 July 2011 - 02:50 PM

I saw a project on RCG for exactly that, it wasnt too sucessfull

You mean the DeltaCopter, I presume. Interesting project, but personally I don't think he pursued the rudder idea thoroughly enough before moving on. He stated that it was perfect indoors but experienced "weather vane" effects in wind. Not surprising, since his rudder was IMO oversized and also the extended tail gave it more leverage to upset things. I think it would definitely work well with a shrouded design, but that's a whole different ball game. Interesting too, that he ended up with a Y4 with coax rear.

See also this video: - seemingly very successful y4 with coax tail.

There's the Scorpion: http://advancedaeria...&id=1&Itemid=50, which seems to have rudder control on all three corners (but double veins on rear, singles on front).

Ah, well... :)
Jeremy

#36 Mat Wellington

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Posted 14 July 2011 - 06:08 PM

You mean the DeltaCopter, I presume. Interesting project, but personally I don't think he pursued the rudder idea thoroughly enough before moving on. He stated that it was perfect indoors but experienced "weather vane" effects in wind. Not surprising, since his rudder was IMO oversized and also the extended tail gave it more leverage to upset things. I think it would definitely work well with a shrouded design, but that's a whole different ball game. Interesting too, that he ended up with a Y4 with coax rear.

See also this video: - seemingly very successful y4 with coax tail.

There's the Scorpion: http://advancedaeria...&id=1&Itemid=50, which seems to have rudder control on all three corners (but double veins on rear, singles on front).

Ah, well... :)


yep, delta copter was the one ! couldnt remember the name

OK, just for you i will give it a go :)

In that HK vid, notice theres no wind ? look at the leaves on the ground

#37 Mat Wellington

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Posted 14 July 2011 - 06:11 PM

I think you might be right about the pitch sensitivity, fixed pitch props can get very pitchy when flying sideways through the air. Normal heli blades are much better but you may as well just make a heli modified for speed if your going to lose the mechanical simplicity of a multicopter.
It's fun to dream up these hybrid designs anywayPosted Image. I've been thinking of a quad with a small amount of thrust vectoring lately myself.
It would be cool to be able to move about slowly without pitching the quad. Finding a tilt mechanism for all four props that's simple is the trick!


thought about that myself
simple answer would be to attach a piece of corroflute under each arm, and have a servo on each piece, and a demon mix in the transmitter

You could let the FC keep the quad perfectly level (put mix to 0) and then manuver with the 4 vanes

#38 Aerhead

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Posted 15 July 2011 - 12:23 AM

Mat

The copter I described in post #34 gives the same level flight with less moving parts and I would guess about the same over all efficiency. The simplest version of the craft would be a Hex setup the same way as the octo but you would lose redundancy of an octo.

Larry


thought about that myself
simple answer would be to attach a piece of corroflute under each arm, and have a servo on each piece, and a demon mix in the transmitter

You could let the FC keep the quad perfectly level (put mix to 0) and then manuver with the 4 vanes



#39 Mat Wellington

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Posted 15 July 2011 - 12:30 AM

Mat

The copter I described in post #34 gives the same level flight with less moving parts and I would guess about the same over all efficiency. The simplest version of the craft would be a Hex setup the same way as the octo but you would lose redundancy of an octo.

Larry


not quite, with a vane under each motor, following teh arms of the quad , you would have level flight in ANY direction as well as full yaw control :)

#40 Aerhead

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Posted 15 July 2011 - 02:40 AM

Mat

I know it's a little hard to understand how the setup I described can fly in all directions. If you have a quad with all the motors tilted outward from the center it will fly the same as a normal quad. If a quad that has all the motor tilted toward the center it will also fly normally. The vertical lift of the motors will be reduced by the cosine of the angle off normal times the thrust of the motors. For 45 degree tilted motors that would be 70.7% of normal thrust.

If the center of gravity is shifted toward one motor, on the quad with the motors tilted inward, then the quad will move in the direction of that motor. The opposite is true for the quad with the motor tilting outward.

When you put the two quads together to form an octocopter you get an interesting situation. With the both quads set to move in the same direction you will be able to fly sideways in level flight. To have it move in any direction you have to have the two CC FC try to go with the same amplitude in opposite directions. The octo will move in the direction the FC for the outward tilted quad is trying to go. I'm quite sure this will work as long as the two FC fighting each other doesn't cause oscillations.

Larry


not quite, with a vane under each motor, following teh arms of the quad , you would have level flight in ANY direction as well as full yaw control :)