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Flexible monocopter drone can be completely rolled up
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Re: Flexible monocopter drone can be completely rolled up
#32I tried to do a similar thing with a single actuator frisbee. The goal would be a frisbee with a single fin could fly anywhere when launched out of some high power launcher. The goal was to make a single-use aircraft which could go anywhere in a city for under $1. By making the aircraft unpowered and under 250g, lots of regulations no longer apply, and it becomes practical to use them to deliver small items. The fin…
I'd love to see your setup and how you attached the fin. I've thought of doing something similar, but instead of a fin, I figured the easiest way to steer the frisbee would be to bend the disc either up or down. Depending on spin direction this should, at least according to my theory, gently steer it left or right. A single actuator mounted to the center of the disc, pushing or pulling on two points on the bottom lip would be all it should take. Intuitively I think this might also eliminate the effects of the asymmetric lift torque since it could continually bias which side of the disc has more lift based on speed, rotation frequency, and angle to keep it balanced.
Re: Flexible monocopter drone can be completely rolled up
#33The first thing I thought of was a single-'wing' maple seed [0]. https://www.researchgate.net/figure/The-Samarai-MAV-design-i...
The first maple seed inspired 100+ years ago https://en.wikipedia.org/wiki/Monocopter
Interesting and thanks for sharing, I also ran into another design that is maple-seed like in terms of aerodynamics. Sadly this is one of the cases where human ingenuity is misdirected and is still causing harm today:
The BLU-43 Dragontooth mine [0][1] and the Soviet PFM-1 [2] which still are responsible for children losing limbs in Vietnam, Laos, Cambodia and Afghanistan.
The BLU-43 came with a chemical deactivation mechanism but of course that failed in a subset of dispersed mines. The PFM-1 in Afghanistan came without a deactivation mechanism, the later PFM-1S had one.
[0] https://en.wikipedia.org/wiki/BLU-43_Dragontooth
[1] https://johnryle.com/?article=the-invisible-enemy
[2] http://www.one-step-beyond.de/en/countries/afghanistan/mines...
Edit: formatting
Re: Flexible monocopter drone can be completely rolled up
#34Earlier quoted context omitted.
Symmetry would ruin the self-stabilizing autogyro descent on unexpected power down.
Would it? Aren’t most autogyros 2-blade? Multi-blade helicopters also use autorotation for emergency landings.
Helicopter autogyro requires deliberate control input. This one enters self-stabilizing autogyro when control input stops at any given operational state.
Re: Flexible monocopter drone can be completely rolled up
#35If you added a vertically oriented 1-dimensional camera, i.e. a single column of pixel sensors, then it could automatically extend that into 360 degree video.
It spins at ~5 Hz. 5 fps isn't great, but this is a cool idea.
Re: Flexible monocopter drone can be completely rolled up
#36If you added a vertically oriented 1-dimensional camera, i.e. a single column of pixel sensors, then it could automatically extend that into 360 degree video.
The ones used in barcode scanners have quite a high refresh rate (100kHz IIRC) so that could be doable.
Mounted on a hinge in a kind of ¬ shape with a weight at the end (hinge at left, sensor then weight at bottom right), it could perhaps capture at an angle in self-stabilizing manner, ie independent of the tilt of the main body.
Re: Flexible monocopter drone can be completely rolled up
#37Earlier quoted context omitted.
What would be the advantage over existing drone technologies? Look at these autonomous drones [0]that can fly through the forest at high speeds. High speed, highly maneuverable and can hold other equipment like a camera. [0] https://electronics360.globalspec.com/article/17357/video-fl...
Cheap. Not every mission requires a stable camera.
If you don’t need stable hovering or tricky maneuvering, a traditional airplane design is almost certainly going to be even cheaper.
Re: Flexible monocopter drone can be completely rolled up
#38If you added a vertically oriented 1-dimensional camera, i.e. a single column of pixel sensors, then it could automatically extend that into 360 degree video.
It spins at ~5 Hz. 5 fps isn't great, but this is a cool idea.
Use 6 of them, each facing at 60 degree angles. That would give you 6 updates per spin, for ~30hz video.
Re: Flexible monocopter drone can be completely rolled up
#39Earlier quoted context omitted.
If by vertical you mean that the frisbee has rotated so the disc is perpendicular to the ground, that effect is actually aerodynamic, not gyroscopic. It comes from imbalance of lift due to two halves of the disc see different relative airspeeds. In competitive disc sports this is usually mitigated by adding more spin (to add more moment of inertia in the spin axis to gyroscopically resist the turn), and by releasing…
I was talking about the fact that the center of lift is ahead of the center of mass of a circularly symmetric wing with positive lift. [1] That force would normally cause an aircraft to 'pitch up' (and hence planes have tail's and carefully balanced weight to stop this happening). In a frisbee, the gyroscopic effect means that this 'pitch up' force actually translates into a 'roll right' motion. By making the rim hea…
Ah hm. I wonder which one of our two effects is dominant. I can see that your explanation must plainly exist - it's just not part of the standard "intuitive" model taught to frisbee players.
That's a really clever fin design.
If the dominant component of rotation was due to the center of pressure being ahead of the center of mass, could you to use timing of the fin being in a "high drag" configuration to pull the time averaged center of pressure back towards to the center of mass?
Re: Flexible monocopter drone can be completely rolled up
#40Earlier quoted context omitted.
I was talking about the fact that the center of lift is ahead of the center of mass of a circularly symmetric wing with positive lift. [1] That force would normally cause an aircraft to 'pitch up' (and hence planes have tail's and carefully balanced weight to stop this happening). In a frisbee, the gyroscopic effect means that this 'pitch up' force actually translates into a 'roll right' motion. By making the rim hea…
Ah hm. I wonder which one of our two effects is dominant. I can see that your explanation must plainly exist - it's just not part of the standard "intuitive" model taught to frisbee players. That's a really clever fin design. If the dominant component of rotation was due to the center of pressure being ahead of the center of mass, could you to use timing of the fin being in a "high drag" configuration to pull the tim…
> could you to use timing [...] back towards to the center of mass?
Yes, but sadly the effect isn't large enough until you end up with a very large fin and a very powerful actuator to move it. That difficulty is what made me put the project on the backburner for now.