The light weight aluminum arms are too flimsy and bend on the slightest hard landing. The tape idea is also too wimpy and upon every landing the alignment goes off and has to be reset. So, with every flight being “out of rig”, it has been a challange to fly it. Also, the urethane foam nacelles are not tough enough. They took some hits on some concrete and served thier function but are now looking a bit worse for wear. Some Arcell will be better.
So, my new vision is to have an airframe that I can hold up 6 feet in the air and drop on concrete from any angle without damage. This is a lofty ideal, one in which I am uncertain as to the proper direction to take at this time. The most delicate corner on the tricopter is the tail. The blade holder that I used is plastic and has broken 6 times already. I can now recommend only aluminum blade holders as being viable.
This picture is before all of the damage. The area where the plywood meets the blade holder is now a BIG glob of 5 minute epoxy. While everything has been easy and cheap to fix, I have been fixing too much and not flying enough. But, when it IS flying it is quite stable and I just want to let it rip ! After all, this tricopter has almost a 3 TO 1 power to weight ratio! But, I need to beef-up the airframe. And the first place is the yaw mechanism. After a lot of searching and seeing a lot of very clever ideas and some absolutely fabulous fabrication skills, It was Alex in Paris, the man responsible for the MultiWii phenonenom, who has what I consider the best, light weight concept.
Look at this picture closely and you will see some compelling design ideas. The first is: The boom/arm extends beyond the motor.With a bit of Arcell foam as a bumper on the end, a huge jump in survivability is possible. This needs to extend to protect the servo as well. The second: It is cheap and easy to build with a low parts count. Does metal to metal cause electrical noise that bothers 2.4 gHz ? Some people will look askew at the strapping tape used to hold on the servo. Is that really so different from double backed servo tape? Maybe double backed tape AND strapping tape is optimum? Something to be pondered. The third: Square tubing causes automatic alignment in these airframes. While I don’t like the asthetics/aerodynamics of square tube, I want to fly and round tubes are not working for me at this time. I am a beginner and I need air time ( and, quite honestly, a lot of it ) . And after all, whats a little drag when you have a THREE TO ONE POWER TO WEIGHT RATIO !! ??
Now, I should review what DID work on airframe # 1 .
1. Plywood works. No failures.
Boy, that was a short list! Every other design element I used was less than satisfactory. But, it does fly and that is testiment to the robust flight control design or the WiiMulticopter. The one thing I did not have in my first design criteria list was:
Fast Field Repair.
(you can’t learn to fly when you are on the ground)
My next airframe will be designed to be easier to repair and KEEP straight so the trim does not change after the repair.
Just for fun, see this concept of a multi-multicopter!
http://www.brodyradford.com/2011/08/ringcopter-concept/
And then, check out this man’s attempt at a man-carrying multicopter!
http://diydrones.com/photo/ecopter-07jul11?context=user
A man-sized quadrocopter!
Until next month on The Next Big THing…
Rocket Bob Kreutzer
