Y6 versus Hexacopter....... Advantages one over the other? Chime in!!

jfro

jfro

Aerial Fun
HPL This is just my understanding. Haven't been told I'm right or wrong. Here is a XY8 flying with Tiger 2814 motors.
http://www.multirotorforums.com/showthread.php?8927-my-XY8-grew-up

I have no idea if this is the complete Bartman build, but I do believe it's one generational back version of his frame..... Near as I can tell the XY8 is basically a quad, but instead of equidistant between arms, their are two arms on each side, none in front or back. Take an X and reduce the distance between the top left and bottom left point, and distance between the top right and bottom right arm. Then their are 2 motors on each arm.

From what I understand, People refer to a flat quad, hex, or octo as having 1 motor on each arm.

Another term I've seen to differentiate between a flat and 2 engine per arm is coaxels. Took me a while to get a y6, x8, 4x8, etc was referring to the coaxel or 2 motors per arm.

Please, someone correct me if I'm wrong on this, but when talking about efficeincy or reduced thrust on the "coaxels", I've read 10% and more in lost efficiency but I've also read where you get some of that back in the 3, or 4 arms that are not being used, ie, reduced weight. Is this a somewhat correct?
 

A

araines2750

Hexa Crazy
Forum,
This has been a hot issue for sometime.
I have to confess up front that I am Bias to the Hexacopter (Obviously).
Please review the following research from NASA & Stanford University.
http://www.stanford.edu/~vinodkl/webpage/papers/JHS042008.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970015550_1997024330.pdf
The finding are clear about the efficient trade offs with coaxial rotors.
Both tests were about a single rotor design. There are obvious benefits in single rotor craft when coaxials allow no tail rotor.
I will say that when you get to the final data, you can use it for your arguement how you may.
I really believe that in our hobby, it is not always about efficiency, but also about usefulness of the design for the intended purpose.
Sometimes it simply a question of looks or appearence that someone may prefer.
Additional research is underway that is looking at the "bubble" phenomenon that has been theorized as existing with multiple blades on the same plane in a circumference around a center plate.
If I locate this I will post, but in a nutshell, it has been theorized that the multi-rotor "flat" creates additional lift with an upflowing bubble of air under the center of the aircraft.
If effiency is the only concern, coaxial loses.
The effiency loss of 5-10% may not be the real arguement, but rather, which is preferred by the user.

Build it, Fly it & Have FUN!!!
That's really what it is all about.
 


Droider

Droider

Drone Enthusiast
DennyR said:
I am planning to put the Naza-H Vid. up next week when it's finished, just putting a GoPro-3 on the side to see the Zen working, thats is. if it stops blowing a gale and pissing down.

I feel sorry for the poor people who came here for a holiday last month. They were expecting blue skies and endless sunshine. At least it's a bit greener.

It did not used to be like this. Five years ago we had to ship water into Cyprus by tanker from Greece, this place was drier than a dead dingos donger, all of the dams were empty. That and the bad forest fires gave me something else to document from the air and add to a book profect. They can have their water back now.

I have a book that sells for 20 euros that also documents the North side of the Island. It was the only time in 36 years that the Turks allowed anyone to officially overfly. It is unique as I doubt that it will happen again in my lifetime. It is a best seller and comes with a 40min DVD full of aerial video production with voice over from David Symonds (BBC).

It is also a good reference for those out there who might one day want to make some money shooting a book. I can tell you how to go about self publishing. You only get paid once to shoot a gig but books can sell for many years.

Most of the images in that book have sold countless times to other publishers. PM me if thats of interest.
Click to expand...

Aye Up Denny.. I have published my own books in another business and it does defiantly work. I had thought about on line books on MR flying set ups etc but time.. how much time do I have in reality to do that... or do I just want to fly! I am always interested in what you are up to so keep posting and I look forward to your Naza H stuff

Dave
 

D

Dewster

Member
I had a bad crash on a flat Hexa after a brittle carbon fiber prop snapped at the hub. This was before DJI's spinning recovery update. I heard a snap, and watched my craft pitch about 90 degrees, flutter and drop like a rock. I was lucky that I didn't damage property and landed in the woods (took me an hour to find the pieces).

I went with the Y6 design hoping for some redundancy in the event of a prop, esc, motor failure. That and DJI's new firmware update should (hoping) prevent another rock falling from the sky incident. My last crash left a nasty taste in my mouth and my wallet. Lol.

The flat hexas do get longer flight times. They float. My Y6 is easier to transport, looks meaner, is very stable in higher winds. I have about 6.5 minute flight time on 2814/11s with two 6000 mah 3s lipos. Her name: Raven
 

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Droider

Droider

Drone Enthusiast
BAD ***! Nice! They do look just like they are meant to work and not pansy around! (guess ill get stick for that!)
 

Benjamin Rowland

Benjamin Rowland

Member
Dewster said:
I had a bad crash on a flat Hexa after a brittle carbon fiber prop snapped at the hub. This was before DJI's spinning recovery update. I heard a snap, and watched my craft pitch about 90 degrees, flutter and drop like a rock. I was lucky that I didn't damage property and landed in the woods (took me an hour to find the pieces).

I went with the Y6 design hoping for some redundancy in the event of a prop, esc, motor failure. That and DJI's new firmware update should (hoping) prevent another rock falling from the sky incident. My last crash left a nasty taste in my mouth and my wallet. Lol.

The flat hexas do get longer flight times. They float. My Y6 is easier to transport, looks meaner, is very stable in higher winds. I have about 6.5 minute flight time on 2814/11s with two 6000 mah 3s lipos. Her name: Raven
Click to expand...

Wow, I know looks aren't everything, but DANG that thing is sharp. Very cool looking build!
 

H

HPL

Member
Jake Bullit said:
And they look cool


IMO :rolleyes:



Sent from my HTC HD2
Click to expand...

Very cool,

Have you considered putting a still camera on a tripod and setting the shutter on bulb while you do a night flight like that? You could even use a hand held photostrobe to shoot a couple of "stills" during the long exposure. Could produce some interesting images.
 
Last edited by a moderator:

P

PilotMan

Member
araines2750 said:
Forum,
This has been a hot issue for sometime.
I have to confess up front that I am Bias to the Hexacopter (Obviously).
Please review the following research from NASA & Stanford University.
http://www.stanford.edu/~vinodkl/webpage/papers/JHS042008.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970015550_1997024330.pdf
The finding are clear about the efficient trade offs with coaxial rotors.
Both tests were about a single rotor design. There are obvious benefits in single rotor craft when coaxials allow no tail rotor.
I will say that when you get to the final data, you can use it for your arguement how you may.
I really believe that in our hobby, it is not always about efficiency, but also about usefulness of the design for the intended purpose.
Sometimes it simply a question of looks or appearence that someone may prefer.
Additional research is underway that is looking at the "bubble" phenomenon that has been theorized as existing with multiple blades on the same plane in a circumference around a center plate.
If I locate this I will post, but in a nutshell, it has been theorized that the multi-rotor "flat" creates additional lift with an upflowing bubble of air under the center of the aircraft.
If effiency is the only concern, coaxial loses.
The effiency loss of 5-10% may not be the real arguement, but rather, which is preferred by the user.

Build it, Fly it & Have FUN!!!
That's really what it is all about.
Click to expand...


Great stuff..... After reading and understanding about 50% of the document.....(yea right) I came across this:

"As expected, for the bottomrotor, the performance degrades significantly (about 40% increase inpower at same thrust at higher thrust levels) compared to that of thesingle rotor because of the influence of the wake from the top rotor. It isinteresting to note that even the performance of the top rotor is slightlydegraded (about 15% increase in power at same thrust at higher thrustlevels), indicating that the bottom rotor has some influence on the flowfield of the top rotor."

In reading further, I saw that there is an induced oscillation from the shockwave of the two airfoils passing. This could be hard on an airframe overtime.....(thats a broad statement)...... And could be the cause of the reduced lift in the top airfoil for that matter because of the change in angle of attack at that frame of time.

 

P

PilotMan

Member
Just read something else interesting......If you have a smaller prop on the top rotor by 8%, efficiency is significantly increased because of the lower blades exposure to more clean air at the tips where a good portion of the total lift is produced. :nevreness:

THATS COOL!!

PilotMan said:
Great stuff..... After reading and understanding about 50% of the document.....(yea right) I came across this:

"As expected, for the bottomrotor, the performance degrades significantly (about 40% increase inpower at same thrust at higher thrust levels) compared to that of thesingle rotor because of the influence of the wake from the top rotor. It isinteresting to note that even the performance of the top rotor is slightlydegraded (about 15% increase in power at same thrust at higher thrustlevels), indicating that the bottom rotor has some influence on the flowfield of the top rotor."

In reading further, I saw that there is an induced oscillation from the shockwave of the two airfoils passing. This could be hard on an airframe overtime.....(thats a broad statement)...... And could be the cause of the reduced lift in the top airfoil for that matter because of the change in angle of attack at that frame of time.

Click to expand...
 

D

DennyR

Active Member
Droider said:
Aye Up Denny.. I have published my own books in another business and it does defiantly work. I had thought about on line books on MR flying set ups etc but time.. how much time do I have in reality to do that... or do I just want to fly! I am always interested in what you are up to so keep posting and I look forward to your Naza H stuff

Dave
Click to expand...
The way that I do it is to use the clients time to shoot extra material that goes into stock for later use. Every couple of years or so I do another book or sell it on. I do about a dozen book signings during the year with the video playing in the background. It pays the bills and promotes the product. The problem with living out here is that you get lazy.
 


Bowley

Bowley

Member
Did Droidworx not have something like that in the pipeine, the Nova I think it was called.
I guess the natural progression for Gressaero is to replace the motor booms with aerofoil wings
 


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