Starting a new thread to show what I'm working on.  I'm building a new Octocopter of my own design.  The goal is to use it for Aerial Photography, lifting a mid-weight camera such as a Sony Nex5.  It will of course be using Arducopter for control.  ;)

I started off researching the various kits on the market, and starting getting analysis paralysis.  I looked at all the options such as Droidworx AD8, Cinestar, CarbonCore, and SteadiDrone.  But I just wasn't happy with the design on them, particularly for the price they ask.  Combined with the fact that I can be pretty frugal, and have a strong DIY ethic, I decided to just design my own.

The basis of the design relies on many of the Hobby King quadcopter parts.  I liked the design of the motor mounts, they are very professional looking, even compared to some of the high end machines.  And I liked that the boom mounts are blocks of aluminum instead of plastic.  Very rigid.  I also liked the look of the dome on their H.A.L. quad, but since they don't sell it seperately, I bought the whole kit, it's only $34, amazing!  I might end up using the rest of it someday, who knows?  So, I basically emptied out their stock of Talon parts, so if you need to fix your Talon quad and the parts are backordered... sorry!

Once that was settled, I set about designing the center frame.  My design required a few things, namely I want all the wiring hidden.  I don't want any spaghetti showing.  Particularly with the ESC's, while still allowing cooling airflow.  This required the center hub to be larger than is typical.  I then needed a smaller subframe to house the avionics.

You can see these plates below.  The larger one houses the HAL dome. You will notice the 3 blue anti-vibration grommets in the middle.  This is the APM1 pattern.  I did that just because.  Maybe I'll use an APM1 as a stand along gimbal controller.  The second plate had grommet mounting for an APM2.  The final plate is the top plate, and has bolt patterns for the Ublox GPS and the magnetometer.

This next photos shows the avionics frame built up with an APM2 mounted.  25mm aluminum standoffs are used. I don't like the plastic standoffs typically used.  They get loose, and lead to vibration.  They also break easily.  This structure ends up being quite rigid.

Here is the avionics frame mounted on top of the main frame.  Yes, the main frame is HUGE.  I actually don't see the point in having a tiny center frame, and then long arms.  This seems like it just leads to flex, and doesn't leave you with any real estate to mount your avionics.  

This photo shows one of my design features.  I put some cutouts on the bottom frame for weight savings, and then made matching cutouts on the top frames.  This creates some nice conduits to run wires neatly.

Here it is with the HAL dome mounted and one of the Talon arm mounts bolted in.  I'm really happy with how stiff the assembly is already.

Here it is with one of the arms mounted.  These are the short 220mm arms, I also got some of the 320mm arms.  One may wonder how I'm going to get away with such short arms and 13" props....  Astute readers will know what I'm planning already. ;)

This last photo shows one of the ESC's in position. This is a Hobby King F-40A, it's somewhat larger than typical 20A units which is partially why the frame is so big.

That's it for now.  I had the plates cut out of aluminum to start with because it's cost effective.  If it all works out, I'll probably have it redone in carbon fiber plate for the weight savings.  I was a little uncertain about the weight, but it looks like the frame will come in at 1070g all in aluminum.  That's about 300g heavier than a Droidworx AD8, but not too bad. It will drop about 1-200g if redone in CF.

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I change my preference to: Premium with CF base and G10 upper.

If you'd have me, I'd like to purchase a CF/G10 set as well.  Really have enjoyed this thread - thanks!

~jake

Went for a flight at the field today, and had a catastrophic failure.  This was my fault, poor design/construction.  Basically the canopy I was using was not fastened securely enough, flew off, and contacted the propellers.  But it was flying great up until that point!

 

 

Several of the prop blades were half-broken in-flight, possibly one half-blade broken right off (not found at the impact point).  I'm also wondering if one of the motors rotated on the boom which might have led to the extreme yaw you can see that builds up.
I was surprised how well the copter was stabilizing while spinning, but the problem is that I think it was trying so hard to stabilize yaw, that I couldn't bring the throttle down.  I was hoping I could land it while it's spinning, but I couldn't get it to come down without shutting the motors right off. You can see where I shut the motors off a few times, and that is ultimately what happened.  I killed the motors, let it tumble and then tried to throttle up just before the ground to stop it but... I think I throttled up up-side down.

Any way, time to rebuilt.  I actually think the electronics all survived, amazingly.  I guess I'll have to get those CF parts cut.

 

I was thinking about trying to build a roll-cage instead of using these canopies, but I'm just not sure of the best way to fasten them?  They would need some sort of aluminum block to mount onto the bottom avionics plates, which I don't really want to supply in the kit as I have no good way to make them.  I still like the dome, I just need to find a better way to secure it.

I basically had used rubber grommets in the bottom plate, with screws in the dome that just pushed into the grommets.  It's similar to how helicopter canopies are retained.

Oh NOOOOOO

Sorry to hear

It looks like it was doing great. you almost got it on the ground.... if it had been a quad or hex, you would have had no chance 

I am not a fan of the round tubs I am going to go glue mine now, it is amazing how soft the motor mounts are I bent 3 with just a little bounce

I am rebuilding this weekend my quad and Y6 

If you cut a new set of alum waiting for the CF cut me a set.

Oh &*$%!

I warned you about the cursed canopy!!!

Amazing how level it stayed on the way down though - fantastic.

And great demo of i-term, the way it leant into the wind no matter which way you were turning!!! With a well tuned gimbal that would be some smooth footage!

Really sorry you have to spend your time rebuilding.

Count me in for a set of dwarfstar plates too in whatever material, and make sure you stick a margin on them :)

I'm working on a roll cage - maybe we should collaborate :)

Sorry to see and hear about your beautifully crafted drone.

My drone canopy is of similar design so I wanted to take a few moments to share my thought, especially since you and Dave C are thinking about solutions.

The solution I have come up with has been rock solid for me so far (not pretty mind you but... ) and quite simple.

I have used 6 large rubber bands (1 from each arm) slung over the top of the dome very tightly. This pulls down on the dome and also evenly to all points on the drone. My dome has a lip at the bottom that all the rubberbands slipover to help ensure there is no slippage. The canopy is simply a tall rubbermaid bowl, and has taken quite a few impacts w/o issue, tho tbh none nearly as bad as what happened in your video.

I have thought much about constructing a cage type device, however I cannot get past the idea that using something resilient vs something with enough tensile strength to survive a severe impact is lighter, easier, and less costly to replace in case of damage than using any cage type structure I have thought of.

Also I have concern that using many types of cages could interfere with electronic signals.

Advantages:

  • Naturally strong shape, which is efficient at distrubiting impact energy.
  • Can be made of a clear and resilient material to enable shock absorption under impact but allow you to see internal lighting indicators. Most of these materials are RF transparent.
  • Fits most current low cost drone designs, which are similar to the design of your copter.
    • Eg. Two flat plates with arms in between.
  • A tall dome can act like a roll cage upon impact, keeping the impact area generally to the dome + 1 or 2 arms vs more helping limit cost of a crash.
  • Light weight
  • Partially water proof
  • Helps prevent intrusion into the electronics area. (Sticks,Stones, Corn stalks, etc.

I think a cage type structure could be successful, but seem to me as tho you would want to integrate that into the whole frame design and also provide some other impact dampening device to protect the electronics besides.

A lexan dome would be great if it was sized appropriately.

It's funny, the guys at the club exclaimed "It's always the canopy!  Canopy or wheel pants bring them down all the time!"

Funny how, the more things change, the more things stay the same.  I guess they have a lot of canopy failures.  I haven't had that, but wheel pants... yeah.  If only somebody could make some good pants and mounts!

I just realized the best way to secure the canopy.  I'll try to get some M3 rivnuts, and install them in the bottom plate.  Then it's just a simple matter to screw it down every time.  Not quite as quick, but easy enough and I don't want this to happen again!

Sorry to read about your loss ...

I have had good results with aluminium under the APM2, it cut the GPS lock time from average 10 to 15 minutes down to 1 to 5 minutes.

what is the actual problem with the waterjet cut holes ? size ? shape ?

you could just cut them as 2mm pilots and we open them to 3mm ourselves ...

above bottom shield: all FR4 / G10 please

below  bottom shield: I think I like Aluminium or FR4 more then CF with all its problems  ...

Nothing is wrong with the waterjet really, it's just rough looking.  Not professional.  All the cuts have this appearance like they've been sand blasted (because they have!) and a nasty burr on them which I have no interest in deburring before shipping.

I suppose I could look into having those CNC cut as well. I'm just not sure there's much advantage (in terms of RF) to be worth the hassle.

Ok, No problem, I would not expect you to do the deburring, I will happily do that myself. (only takes me 3 minutes per plate)

Don`t try lazercutting, as that will give you a warp in the plates (depending on the size) AND a very nasty burr !

You will find that CNC cutting, unless the workshop is speziallised in aluminium, will give you a burr as well on both sides (as aluminium tends to "smear"), the edges will be cleaner though. But it will be more expensive too...

I sanded all the HK CF landing gear parts too, as I didn`t like their "sawblade" texture

definitely interested in buying main plates cant be bothered to dremel them myself and can't afford cnc 

did you have any luck getting plates and at what price?

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