Who am I kidding right? its almost impossible to design an indestructible quad copter frame! That's why this frame is actually the complete opposite. Its designed to fail!
This is nothing new. Most designs nowadays are designed to fail, but they are designed to fail correctly and safely. There is always something that needs to be protected and for that to happen something needs to fail. Like crumple zones in cars or pressure relief valves on pressure vessels.
In the case of a quadcopter, I'v got not passengers to look after but I would like certain parts (the expensive parts) to survive crashes. Also after crashes it should be easy to fix.
Iv taken what Iv learnt from my arducopter v1 frame (which is now very tired) and my engineering diploma and put together a frame that will protect all the valuable items and break the cheap readily available parts.
So, every nut and bolt is nylon except the motor mounts. Any hard impacts will shear the bolts and save the frame. This happened alot with my arducopter frame. its a good thing =) rather break a bolt or 2 than a landing gear. I will be placing some high density foam right in the center of the frame for when an arm gets pushed into the frame. This should absorb some energy and stop further damage as those carbon booms dont break easily. I have placed the motor mounts slightly inside the boom as I think they are vulnerable at the ends. Yes, this now makes booms vulnerable but nothing a rubber stopper cant fix =) Where the arms meet the frame and motor mount I want to put thin strips of high density foam to absorb some vibration from the motors and also absorb some energy in crashes.
So hopefully all I will be replacing after crashes is nylon bolts. Even if not, I still like the frame =)
More about the frame itself:
The arms will be shortened 450 heli carbon tail booms from HK, $2.40 link
The carbon sheet is 1mm thick also from HK which I will cut with a dremel, $10.79 link
landing gear will be 3mm clear Perspex strips bent will mini blow torch
Motor mounts will be 4mm perspex discs made with a hole saw and file =)
Electronics, motors, etc will be from my arducopter frame.
Will post a build blog when its done.
Please criticize =)
Comments
Thanks alex! why would recommend the tube clamps though?
Dont mind sharing the motor models, The ones you see in the pic I got from grabCAD. They not the same as the arducopter ones. I have however made exact models them (AC2830-358, 850Kv), just been to lazy to mount and render them. What CAD format do you want them in?
Looks cool, but I would suggest that you get some tube clamps, or get square arms, but otherwise seems nice. Would you mind sharing your motor models with me, I think you did a very good job with them :)
HK does have tube clamps but always out of stock. The motor mounts cant turn as 2 of the 4 screws go through the boom. Where the boom meets the center part is exactly the same as arducopter v1 frame, one screw through arm and 2 on either side to stop rotation. However, my situation is less ideal as my arms are round ( Im assuming this is what you see as the failure?) but will see how it goes in the build=) might have to start up the milling machine...
Thanks for the +ve crit =)
joints between tube and center part and motor mounts will not work. You will need some clamps to pinch tubes, otherwise they will fail under scews pression. Motor mounts could rotate in flight if tube fail, with distastrous consequences. The good news is that if hk does tubes, it must do clamps also (fuselage wise), so there are chances all the pieces you need exist already! :)
Id still like to build one like Jose Julio's using kit parts, man that thing is indestructable. Great to learn earobatics=) The low inertia of the small quads is the main factor of its strength though. For now though, I need a normal size frame to carry a payload. (camera, fpv, etc)
Its Inventor stephen =)
I was thinking about changing the top stand-off's to metal so the ardupilot mega is sandwiched between to carbon sheets. Not much is going to get through to that. As for the props, they are cheap and easy to replace. Adding rings and stuff around the props is adding another item that will break in a crash and its not as easy to fix as a broken prop.
I'm surprised there aren't a few more designs with some manner of safety cage. You could at least create areas that would save the electronics and the props in the event of a failure.
Is that Solidworks or Inventor? (Or something else?)
well, you COULD design an "indestructable" frame... just keep your quad small and use robust parts
search for jose julio's mini quad, it's nearly unbreakable