Finally getting to the meat of a project I've been thinking about for a while, a way to use something besides DJI arms on a TBS Discovery. The other day I did a block setup for 17mm carbon fiber tubes which I'll eventually get setup on a frame and test fly. Before doing that I decided to go a little smaller and give the designs a try on a smaller scale mainly because it will be easier to just swap the arm out from under what's already built and flying rather than what amounts to an almost total rebuild to use the larger tube and motor/ESC setup.
Here's the original prototype block on the right and what will likely be the final version for the smaller tubes on the left...
This block is setup to take a 13mm tube and use a scaled down version of the lowered motor mount I did for the bigger motor. This keeps the mass of the motor more inline with the center of the tube rather than up above, helping to keep the center of gravity lower which should allow for smoother handling in the air.
I've got the full set of the final design blocks on the printer now, tomorrow I'll cut a set of aluminum tubes on the lathe then drill and tap them for the locating bolts. Going to go just a bit longer than the DJI arm intially so it will be a fair comparison to the stock setup, should be interesting to see the difference in flight characteristics and if the reduction in drag from the DJI girder arm to the small section tubing yeilds any gain in efficiency. If it does I expect it to be small, I think the way it flys will be affected more.
The nice thing about this design is it's easy to change it and scale up/down for different sizes of tubing, a matter of a few minutes in the CAD program to make the change then print. Initially I'll be using aluminum tubing in 13mm mainly because I have it on hand, I'll be ordering a couple different sizes of C/F tube this week for this and a couple other projects.
If anyone has or has access to a 3D printer, I'll let you have the STL files if you want to give it try for yourself. The blocks are setup to be held in place using 3mm bolts and captive nuts inserted into the sides of the block, the tube is held in place and straight by a through bolt in the block with captive nut at the bottom, and the motor mount by a 3mm bolt going up from the bottom into a corresponding hole in the arm.
Ken
Here's the original prototype block on the right and what will likely be the final version for the smaller tubes on the left...
This block is setup to take a 13mm tube and use a scaled down version of the lowered motor mount I did for the bigger motor. This keeps the mass of the motor more inline with the center of the tube rather than up above, helping to keep the center of gravity lower which should allow for smoother handling in the air.
I've got the full set of the final design blocks on the printer now, tomorrow I'll cut a set of aluminum tubes on the lathe then drill and tap them for the locating bolts. Going to go just a bit longer than the DJI arm intially so it will be a fair comparison to the stock setup, should be interesting to see the difference in flight characteristics and if the reduction in drag from the DJI girder arm to the small section tubing yeilds any gain in efficiency. If it does I expect it to be small, I think the way it flys will be affected more.
The nice thing about this design is it's easy to change it and scale up/down for different sizes of tubing, a matter of a few minutes in the CAD program to make the change then print. Initially I'll be using aluminum tubing in 13mm mainly because I have it on hand, I'll be ordering a couple different sizes of C/F tube this week for this and a couple other projects.
If anyone has or has access to a 3D printer, I'll let you have the STL files if you want to give it try for yourself. The blocks are setup to be held in place using 3mm bolts and captive nuts inserted into the sides of the block, the tube is held in place and straight by a through bolt in the block with captive nut at the bottom, and the motor mount by a 3mm bolt going up from the bottom into a corresponding hole in the arm.
Ken
