Think I would wear heavy long pants, shoes, and eye protection around that.... But Awesome build! Keep us posted on the progress!
Ha, would probably be smart. The foam airfoils wouldn't do much damage but a flying piece of plastic has the potential to cause some damage.
Currently mocking everything up on the CAD for the new design, have some finishing touches to do with the new parts but the main ideas are all there. I have a new transmission - I'm going to couple 2 4:1 pulley systems together to achieve a resultant 16:1. This will hopefully allow me to double voltage (which results in higher motor rpms, so I am converting it to more torque through this reduction). This should also keep the motor heat down.
I also have a new vectoring mechanism, which will be on the inside of the rotor instead of the outside. The new linkage gives me control over 360 degrees of rotation, as well as pitching from 45-20 degrees. Theoretically I can use the same linkage design (with a few changes) to do 45-0 degrees, but it would probably be much less stiff so I'm going to look at that after I verify that this works. The only real downside to this design will be that I will have to include a 2nd servo (SG90 so an extra ~10g). This is not great as each rotor will weigh 90g without the steppers, so that adds on an extra 20% to the weight. Should probably try to find a lighter way to do that, let me know if you guys have any recommendations for mini servos or steppers.
There will be no center shaft, as the rotor will be supported externally by the frame. I am doing this in an attempt to stiffen everything up, as that was an issue on the last copter. I'm going to take the time to design a stiff frame and adequate ground strike protection for the rotors. Finally, I am including a 3x1.5mm carbon fiber tube as a spar in the blades. This should stiffen everything up slightly, but the real benefit is that I will be able to screw the bearings directly into that instead of needing to epoxy plastic plates onto the foam. Every single structural failure that I've had was because of the foam ripping near the plastic plates, so this should significantly increase robustness.
All together, I'm hoping for a significantly stiffer rotor. The last design warped too much when I tried to apply higher voltages (3s -> 6s, got like an extra 10% thrust), so this will hopefully be able to handle that. Oh - and I'm increasing both the wingspan and diameter from 150mm to 200mm. Looking at the non-dimensional coefficient of thrust I should
theoretically get ~1080g thrust per rotor instead of the previous ~320. However, it's somewhat thought that the unsteady aerodynamics get less favorable as you increase size, so we're looking at a realistic 750g? Honestly no clue but it's what I'm shooting for. The same 4.7:1 thrust to weight from the old rotor would mean that I really just need to get over ~450g thrust for this to be an improvement in that aspect. I'm also looking at doing an experiment on the aerodynamics side of things that reduced power consumption by ~40% in a CFD, which would be pretty crazy to implement too. Not sure how good it is experimentally though.
tldr; Basically I have new things to try that should hopefully double the thrust to weight? Also sorry for the long post, I'm trying to step up documentation efforts and figured I'd just do that in here because I kinda already stole this thread from Nick.
EDIT - controls: forgot to mention this but the reason I chose the configuration of the 4 rotor was a) to stiffen everything up with as much support as possible and b) to benefit from the change in rpms when leveling. I noticed a significant difference in pitch vs roll stability on the last copter due to increasing rpms leading to torque that levels the craft. On the controls side, I am planning to use only the RPMs to stay level, and use the thrust vectoring for translation. Flight controller/RPMs will keep it level, and the stick inputs will pass through to
only translate the copter. This is to highlight the unique benefit of the cyclocopter's thrust vectoring - the ability to translate without changing RPMs or tilting - meaning that it
should be much more maneuverable than a quadcopter. Anyway that is all, let me know if there are questions or thoughts on anything.
