I've become a bit tired of having to order frame parts from China every time something breaks or when I want to try something new so I've decided to design and build my first frame from scratch using material I can get in the local hardware and hobby stores.
I also want this frame to be my general-purpose aerial survey/FPV quad and it seems like the H-frame design has some advantages. I've just spent a few hours fiddling with this design in SketchUp and would appreciate any feedback or suggestions. It is strongly influenced by Graham Dyer's Carbon H-Frame, particularly the ability of the arms to be folded for easier transport. In my current design, I have all the electronics spread around but might consider combining most of them under one shell like Graham did. I've added the option of having the arms perpendicular or swept away from the body to the front and back to keep a front-mounted camera behind the centers of the front motors. It seems this configuration is common on some of the H variants but I'm not sure if there is that much advantage to it.
Below is an image of the basic layout. I plan on using 13mm channel aluminum for the body, 1mm carbon fiber sheet for the top and bottom deck, and 13mm square tubing for the arms. The body is 450mm long, and the motors are 376mm apart side to side and 400mm apart front to back in the perpendicular configuration. If both front and back arms are swept, they are 330mm side to side and 570 front to back.
One thing I haven't seen before in other H frames is the ability to have a camera sitting on the top deck ( with vibration isolation, etc) and shooting down through the frame. Maybe this isn't uncommon but I'm trying to avoid having cameras hanging underneath and the need for long legs etc.
Below are the top views in the three arm configurations.
I'm not afraid to jump into this project expecting a lot of trial and error but I'd appreciate it if anyone sees some fundamental problems that I should avoid. My next step will be to figure out how much this will weigh and see if the motors, props, etc that I have to spare will be up to the task.
Thanks!
Jason
Replies
Jason, how is your build going?
Hello,
Just wondering how this progressed? I am think of building one that can handle 16 to 18 props and 8 motors out of carbon fiber.
Thanks for the mention Jason, I abandoned my carbon H frame as it was just too heavy and built my EPP foam H-frame instead (http://diydrones.com/profiles/blogs/epp-foam-folding-h-frame-quad).
It is still flying to this day and has flown in at least 4 different southern African countries, had probably more than 500 flights and survived numerous "incidents". It used some parts from the carbon H-frame notably the sections of carbon holding the arms.
The carbon H frame could've been lighter but the aluminium and carbon I used were thicker and heavier that what I would've liked but at the time that was all I could get hold of. The layout of the EPP one was much better and folded MUCH smaller. Camera's go on a ply and dowl plate which pushes into holes in the foam, very simple and robust.
Twist is also no longer a problem with the H-frame config in the MP so an H-frame doesn't need to be even half as stiff as my carbon one was.
Graham, thanks for your comments. Your foam copter gives me a whole different approach to consider. I love how compact it can get with the arms folding over the rest of the body. For now I think I'll keep investigating the Al/C frame with more emphasis on keeping it light. I have a few ideas about how to reduce the weight, including your suggestions to use thinner carbon fiber. I'll post updates about my anticipated weight in a few days, and if it seems reasonable, I'll try to start building as soon as I find a chunk of time. Then, whether it works or not, I'm sure I'll be looking into a foldable EPP craft in the future!
The forums don't seem to like SketchUp files so I'm trying to attach as a ZIP in a comment.
quad11.zip