XY-8 Build

[DucktileMedia]

Twitchy little thing!

The best part about you doing this is that it proves the motor position does not have to be equally spaced.

Nice work!

 

[Bartman]

it was pretty stable but i was working through the fog of a minor migraine headache today so the flying could have been better.

thanks,
bart

 

[matwelli]

looks like she has power to spare, very responsive, good job.

did you run diferent gain setting between pitch and roll to compensate ? (i know i do on the long vtail8)

 

[Droider]

Nice one Bart looks pretty stable to me...

Dave

 

[llamatrails]

Which mkm configuration file did you use ?
Did you have to modify it at all ?

 

[Bartman]

Rick,
I used the standard X-quad file then just added four more motors and configured them. When you look at the std quad mixer, make the motors with the same direction of rotation have the same yaw values, the motors on the same sides (left or right) have the same roll values and all the fronts (or backs) have the same pitch value.
I was out flying my DW flat Okto today and it was windy where I was flying. As a result the motors had multiple cameo appearances rendering the video worthless. Guess what I was thinking about, yes, an XL-XY-8 with my good mount on it. Guess where I'll be tonight, yes, in the basement building an XL-XY-8!!
Why haven't I already done this?!?!?

 

[Droider]

XL-XY-8!!

Eh!?

Is this just a bigger version of what you have built?

Dave

 

[Bartman]

Dave,
I thought it fitting to make the designation as confusing as possible, hence the XL (el largo) XY (Quad with Y tendencies) -8 (El numero de whirliwhipperos)

XL-XY-8

It's on the bench now, coming along nicely, thank you.

Bart

 

[llamatrails]

Rick,
I used the standard X-quad file then just added four more motors and configured them. When you look at the std quad mixer, make the motors with the same direction of rotation have the same yaw values, the motors on the same sides (left or right) have the same roll values and all the fronts (or backs) have the same pitch value.
I was out flying my DW flat Okto today and it was windy where I was flying. As a result the motors had multiple cameo appearances rendering the video worthless. Guess what I was thinking about, yes, an XL-XY-8 with my good mount on it. Guess where I'll be tonight, yes, in the basement building an XL-XY-8!!
Why haven't I already done this?!?!?

Thanks for the info, Bart. Sounds like I can take my existing X8 config and plop it into a new XY-8 frame. Appreciate the pioneering work. !!!

 

[Bartman]

Here's a pic of the XL-XY-8 that was completed this afternoon. It flies just as well as the big flat 8 donor-kopter so I'm probably going the XY route from here on out. the big test comes tomorrow when I see if it will fit into my 4-door Civic.

View attachment 1381
FWIW, the tops motors all turn one way and the bottoms all turn the other. no problems that i can see with it so far. will put the GPS/Navi on tonight and give it a try tomorrow.

Bart

 

[Mactadpole]

Fantastic!!! Bart, really good looking copter. When I was looking into coax redundancy I read that having props spinning in an alternate pattern provided better redundancy in a multi-motor failure scenario. But, no one could/would (take the time to) ever provide an explanation of the theory because it was very complex. This was discussed briefly on the RCG-Hoverfly forum.

I am very excited to see some flights from you with this copter!

What size props are you spinning?

Still trying to find some time to post about my recent travels...

Shawn

Here's a pic of the XL-XY-8 that was completed this afternoon. It flies just as well as the big flat 8 donor-kopter so I'm probably going the XY route from here on out. the big test comes tomorrow when I see if it will fit into my 4-door Civic.

View attachment 2316
FWIW, the tops motors all turn one way and the bottoms all turn the other. no problems that i can see with it so far. will put the GPS/Navi on tonight and give it a try tomorrow.

Bart

 

[Bartman]

Thanks Shawn. Whats interesting to me is that I was having harmonics in the flat Okto causing jello in the video picture. I was considering longer arms to make larger props (and therefore slower RPM's) an option but then I'd have more instances of booms/motors in the video shots. By switching to the XY format I'm able to go to 16" props if I wanted to while still using the standard length Droidworx arms. My Avrotos couuldn't turn 16" props but it just shows how much things change with a simple reorientation of the format.
Bart

 

[DucktileMedia]

Maybe it's counter-intuitive, but is there any reason the craft would be less stable in the pitch cyclic due to the decreased spacing from motor centers? For some reason in my mind, I pictured it wobbling more in the pitch than the roll.

 

[Bartman]

it may very well be but I can't perceive it in flying and I can't get the kopter to show pitch as being less or even un-stable. I flew it with the camera mounted yesterday and had it leaning at least 45 degrees forward in fast forward flight and it handled it perfectly with total ability to stop and even double back on itself. Roll seems to have no less authority. i don't see myself building anything but this format in the future unless some other application requires it.
thanks,
bart

 

[homer911]

Bart, nice sutup, seems to work. What size props are you using? I take it they are different pitch top and bottom?

 

[Bartman]

Hi Homer,
I'm using Xoar PJA and PJN props, so far they both perform about the same with the PJA giving a bit more lift with its fuller blade profile. I have 12x5's on top and 12x7's on the bottom. I've used the 12x5's on top and bottom and it flew just fine but with the -7's on the bottom I have much more stable descending flight with virtually no wobbles even when leveling off. The tops all spin clockwise (looking down at them) and the bottoms all spin CCW. There was talk a while ago about stability with all the tops spinning one way and the bottoms spinning the other but I just don't see it. With the bottoms spinning CCW, I have a wider assortment of props to choose from since all of our planes' props spin that way plus they're usually in stock where I order them from when I ding a couple. The tops are usually spared from getting any damage, hence the less available CW props on top.
I may have just frames available sometime soon, the details are being worked out to see if it's feasible.

 

[homer911]

Thanks Bart, interesting setup. With the top CW and the bottom CCW is there is redundancy with this? I expect the would be yaw issues, but I suppose thats to be expected with a motor out...

 

[Bartman]

Steven
i don't think my motor-out performance would be any different from any other coaxial quad. If you lose a motor or prop it's up to the FC to compensate for roll/nick/yaw and all we can do is cross our fingers and hope we have control authority to get it back on the ground in one piece.
Here's a video I shot a few days ago in front of my house. I wasn't trying to be really smooth so there are places where I'm obviously yanking it around. At about 2:50 you can see the wind is blowing through the trees and there's a spot where I'm descending down with just a couple of slight wobbles initially from my clumsy thumbs. The video is unprocessed except to convert the format for easier uploading. In the video the frame is version 2 1/2 and the camera mount is version 4. New builds will be getting frame 3 and mount 5, mount 5 will be flying by Wednesday and I'm in the process of finalizing a cut shop and materials for frame 3. The camera is a Canon T2i with a Sigma 10-20 lens.

Bart

 

[mailman35]

man that thing is a beast, no wonder it didnt really get tossed around in the horrible wind thats been around for most of the week

 

[homer911]

Hi Homer,
I'm using Xoar PJA and PJN props, so far they both perform about the same with the PJA giving a bit more lift with its fuller blade profile. I have 12x5's on top and 12x7's on the bottom. I've used the 12x5's on top and bottom and it flew just fine but with the -7's on the bottom I have much more stable descending flight with virtually no wobbles even when leveling off. The tops all spin clockwise (looking down at them) and the bottoms all spin CCW. There was talk a while ago about stability with all the tops spinning one way and the bottoms spinning the other but I just don't see it. With the bottoms spinning CCW, I have a wider assortment of props to choose from since all of our planes' props spin that way plus they're usually in stock where I order them from when I ding a couple. The tops are usually spared from getting any damage, hence the less available CW props on top.
I may have just frames available sometime soon, the details are being worked out to see if it's feasible.

What is the difference between the PJA & PJN props? Does it matter where you put them? Top or bottom?