Gunters new octocopter build

[Gunter]

Hey Gunter

Why powder coating and not anodizing?

Ben, to anodise aluminium, it has to be a certain grade, otherwise it's not possible. I know the booms are okay to anodise, but not sure about the other bits...it's something I have been meaning to find out because anodising looks nicer! I also have a powder coater 1/2 mile away from me who does work for a good price.

 

[JLO]

Hi.. guys like you make this forum so rich with useful info thanks ....
Question why did you choose aluminum instead of carbon fiver for your buid
thanks again

 

[Gunter]

Hi.. guys like you make this forum so rich with useful info thanks ....
Question why did you choose aluminum instead of carbon fiver for your buid
thanks again

Hi JLO,

I used aluminium because it is so much cheaper than CF. I had a look online today for carbon, a sheet 400mm X 275mm costs £50. You then have to still have it cut. Then the booms would probably cost about £20 each at a guess, so the airframe would end up costing quite a lot. (My ali booms cost £2 per 2 metre length!) I figured instead of having a very light frame and carrying a 1.5kg payload, I would rather save money, have a slightly heavier frame, but then use a 600g camera. The overall weight is the same, but at a better price. It also makes sense if I have a crash, because I have loads of cheap spare parts!

 

[JLO]

Hi again you are totally right on the price for CV, is way more $ another though using square booms instead of round....hmmm would be an issue with wind?
square boom could mean less of the round to flat clamps whats your though on that

 

[Gunter]

Hi again you are totally right on the price for CV, is way more $ another though using square booms instead of round....hmmm would be an issue with wind?
square boom could mean less of the round to flat clamps whats your though on that

Square booms would cause a bit more turbulance with wind, but as you mentioned, no need for boom clamps. Personaly I prefer the look of round tubes, even though it's a lot more work!

Gunter.

 

[jes1111]

Booms under the props are also a major source of vibration which you then have keep away from the camera. Square booms will produce a higher amplitude of vibration than round ones (more surface area presented), but best of all would be streamlined (tear-drop) booms. Primary frequency of the vibration will be twice the rpm (or three times for a three-bladed prop), e.g. at 5000rpm, two blades => (5000*2)/60 = 166.67Hz. This relatively low frequency vibration is the hardest to isolate, since the natural frequency of the isolation material/mechanism should ideally be less than one fifth of the source frequency - at 5000rpm that's 33Hz or less. Possible, but not easy

 

[Kilby]

How would this change if you configured a craft to have the booms over the props, if any at all? I've seen some guys build out tricopters in this fashion and they seem to have had good results. It ends up looking more like a lawn mower than a multi-rotor, but if it works better who cares.

 

[jes1111]

Theoretically it should be much better. Remember that a straight swap from top to bottom mounting will likely need a re-tune of parameters since the centre of thrust will move downwards. Also watch out for the props getting in the field of view of the camera - that'll change with an underslung mount. If you try it let us know the result

 

[Kilby]

I've been thinking of trying it for sometime now. Maybe I'll give it a go this/next weekend. I can take just the top motors off of my x8 and try it that way.

-Terry

 

[paktazh]

How much it cost to build one of these U should make a movie of how u build it and the link for the parts'

Thanks

 

[Gunter]

How much it cost to build one of these U should make a movie of how u build it and the link for the parts'

Thanks

Making a movie is out of the question at the moment, I'm afraid...I wouldn't have enough time! I have listed a few of the components here on my other site. There are a few usefull links.

Depending on what parts you buy and what spec you are looking at, a full set of parts could cost you £2000 - £3000.

Cheers

Gunter.

 

[Droider]

Fraid I can't Dave. The esc's seem to be struggling with the smaller props and shut down today when flying-I'm going to have to upgrade them before I do anything else!

So what happened? what esc's have you on board?

Dave

 

[Gunter]

Been busy tonight! Fitted new 40A esc's, made the booms 40mm shorter and reconfigured the LED harness so that it uses its own battery. M2M distance is now 830mm. Now to refit the WKM parts!

Gunter.

 

[Gunter]

Had a little brainwave last night. I have a spare centre plate, so I've tried mounting it on top for the batteries. I can use either one or two batteries...I looks like it might work!

 

[Macsgrafs]

Looking good Gunter, I like the way your ESC's are mounted...wish I had done that

ross

 

[ssjheli]

Looking very good Gunter.

Curius to hear a flight report.
I can see you have chanced the motors so how is your setup right now?
Søren

 

[Gunter]

Looking good Gunter, I like the way your ESC's are mounted...wish I had done that

ross

Ross, it seemed the obvious place when I was doing the cad model, it works well. It's just difficult to feel how hot they are though.

Looking very good Gunter.

Curius to hear a flight report.
I can see you have chanced the motors so how is your setup right now?
Søren

Søren, it's flying very well. You can see how stable it is in the video link below. That video was done with 30A esc's which were getting very hot, so I have just changed them for 40A Hobbywing esc's. I will take it for a test flight tomorrow and adjust the gain settings. I will do another short video afterwards to see what it looks like.

The new weight is 4kg, including gopro camera and lipo 5000mah battery. 12x4.5" epp props.

http://www.multirotorforums.com/showthread.php?1459-Flight-stability-video

 

[Gunter]

I've been thinking of tweaking this beast a bit. It currently weighs in at 4kg including 1x 6000mah battery and the gopro camera.

Having got a bit of inspiration from Kens build and a bit of free time over Christmas, I thought I would have a new frame cut and powder coated, then rip out the wiring harness and fit a PDB. The main plates have had a lot more material removed, similar to the CS and I have made the upper plates smaller to save more weight. Also the LED holders on the booms have had a diet!


Centre plates and power distribution board
View attachment 1789

The next layer with WKM installed

View attachment 1790

Everything together with the batteries now on top instead of underneath. They are so much easier to change this way!

View attachment 1791

I even had the idea of powder coating the frame orange. I don't have time to render it perfectly, but a quick shading shows what it might look like...still not sure!

View attachment 1792

Now, I had best get this lot manufactured before the Christmas break!!

 

[plingboot]

gunter, any chance you could have a few extra led mounts made - i noticed the one you had for the wkm led at dz2 meet and thought it was a neat/elegant solution. if it could be bolted to the flamewheel (or other frames) i'd be in the market for one.

 

[BorisS]

Gunther cant you reduce the actual WKM components plate even more. The only component that actually needs real stability is the IMU hard mounted to the frame to get the best feedback. The MC PMU etc. need a minimal surface to be attached.
You once asked me about the landing gear of the CS8 / CS6. Actually you already have the boom clamps that would make it possible to construct a similar landing gear/three legs, probably lighter approach. This also goes hand in hand with the thought of mouting the lipos over the center plate with the standoffs. What the box with the green edges ?

Boris