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 =)