V6 and V8 Frame Designs

[ovdt]

Hey guys,

I'd like to discuss this topic extensively. I know that Matt is a big fan of V-tail design. I'm also considering building a V8 frame but as far as I've searched, V design is patented by another German multirotor company called Asctec. (asctec.de) They have a multirotor system called Falcon V8, which I must admit quite impressive. I'm sure the prices are much much higher than I expect but, the clear view of camera and easiness of orientation were aready enough to convince me. I believe it has some drawbacks like not able to put heavy camera into the front.

(you can read the patent issue here: http://mikrocontroller.com/files/AsctecPatent.pdf )

I wonder if you have spotted any succesful V-6 or V-8 designs on the web? A mixer setting for V-6 exists on mikrokopter web site: http://www.mikrokopter.de/ucwiki/mkm#Hexa

I checked the configuration settings with V6, and it seems we can easily adopt that to V8 too.

What do you think guys?

 

[Gunter]

I think it's a very clever design for getting a good view from the camera, up and down. With regards to the patent, I'm sure you will be okay building something similar. I think they would be more concerned if a manufacturer stole their idea and started mass producing them, but for one person to build a similar device shouldn't be a problem.

I have used ideas on my build from lots of different designs, I can't see a problem unless I mass produce and do them out of business!

Gunter.

 

[Ododobe]

I'd love to help.
Unfortunately I don't speak German so it is unclear exactly what Asctec is claiming a patent for.
Could you give us a brief outline of what it is that they are claiming is unique to this design.

Is it the fact that the motors are aligned in a straight "V" formation?
If not then this should be easy to overcome.
If it is it could be a bit tougher.

 

[matwelli]

its the V shape that they say they have the rights to i believe, saying it unique in alowing a clear forwarward view - same could be said of a Y6 design - so i dont know how well they would defend it

I changed mine to two straight rows of three motors,and the Vtail on the end.

That config, can carry a large camera, mine handles a kilo of camera if required, as the batteries act as a counter-balance (like a crane)

The one prob with the V8/Vtail8/V6 etc is they are a bit susceptable to side winds, lifting the windward side, with that large,long prop area.

The V6 may present an interesting challenge on the mixing when it comes to roll control, to keep the tourque in balance.....

lets say you want to roll left, so you need to speed the three right motors up,if you speed all three up, you will have a net gain in tourque that tries to spin clockwise.

so you need to speed the centre motor up twice as much as the other two

 

[matwelli]

forgot to say - for me the best part of the V designs is the ability to carry a camera , with great viewing angle, and not having t have landing gear, or a camera hanging below to get damaged

the negative is having to adjust the battery location depending on battery and load changes

 

[ovdt]

I agree Matt, without a landing gear, the total weight would be much less.

I think the patent prevents Mikrokopter to release an official V8 mixer settings.

Ododobe, I don't know the exact specs of V8 frame, maybe Matt can shed some light on this, but as far as I've looked into, it looks the arms are positioned 30-35 degrees to each other.

When a 12" prop is used, the long arms should be around 42-43 inches long.

The distance between the back sides of the arms should be 14-15 inches long.

View attachment 1230

I'm no expert on drawings but, by using square tubes the design would be quite easy.

 

[Ododobe]

View attachment 1231
Another option would be to do something like this where the viewing angle is increased by making the front arms 120 degrees like a Y6.
I imagine with he two arms out the back instead of one you would have lifting capabilities closer to a true X8.

Mounting the camera as far forward as possible could be offset by using a length of threaded rod out the back with a weight that you can screw in and out to adjust the center of gravity. Because you are moving the weight out it means that it would not have to be the same weight as the camera but some trial error would be needed to get it right. Plus once you take the camera off you could work it so the rod is removable, unless it is needed to adjust the CG.

Unfortunately I did get as far as to work out the landing gear

 

[Ododobe]

ovdt

By using the dimensions you mentioned it looks like you are going to end up with something like this.
View attachment 1253
This is using 13" props.
It ends up being a big frame.

The V6 may present an interesting challenge on the mixing when it comes to roll control, to keep the tourque in balance.....

lets say you want to roll left, so you need to speed the three right motors up,if you speed all three up, you will have a net gain in tourque that tries to spin clockwise.

If you you increase the speed of two motors on one side would not reducing the paired motor on the other side by a factor of 2 not compensate?

View attachment 1254

Or is torque another one of those ones that increases on a curve rather than straight line?

 

[ovdt]

Hello again Ododobe,

Using a coaxial setup like yours will require a landing gear. That's something I would avoid.

Yes, the V8 frame ends up very big. Asctec Falcon is also about 1 meter long, as far as I know.

Thanks for the drawings by the way

The only topic I could find was this:

http://forum.mikrokopter.de/topic-19919-1.html

Apperantly he is using the Octo-U mixer.

And a video:

http://vimeo.com/16585684

 

[Ododobe]

I had a flash of inspiration and came up with this using the same motor layout.

View attachment 1275

Only issues I can think of are the fact that you would probably need to make it out of carbon fiber square tube and notch the spars to make the frame and wrap the joins with carbon ribbon and resin to make them strong enough and keep weight down.
Of course you could do something similar with aluminium square tube and fiber glass.
Added bonus is that if the aluminium frame fails you can always use it to get better reception for your TV.

Also with the camera mounted so far forward you will need something out the back to stabilize it like I suggested earlier.

The only other issue I can think of is the loss of amps/watts/volts traveling through such long wires.

Odo

 

[ovdt]

Hello Odo,

I must admit that your design is very clever! Thanks!

I'm going to build that design in a few weeks and will see how it works. I have lots of aluminium square arms and will use them.

 

[Gearymeister]

Hi Guys,
i was wondering how this project turned out? I'm just building an octo v frame and have found that its tough finding any info indecating how best to set it all up.

i was wondering what control script you are using? Multiwii or megapirate? and if you had any information on the sketch to load up?

thanks

chris

 

[Silverburn]

I've built one of these. Still running it in V4 at the moment - will upgrade to V8 soon.

This is it with a TBC Disco for size comparison.

View attachment 13767