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Sep 18, 2019, 06:48 AM
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Discussion

timelapse camera platform


Hi, in reviewing my failures (proudly posted previously) to build a suitable platform to hover in one place and take images over at least an hour -
I have read this paper presenting a swatch plate-less heli type drone.

I only have a payload of a hi-res still image camera.
There are hybrids, skeletal battery hanging quads and other designs out there.
For a few tens of grams payload, these are overkill.

It has to be a wind-free day, even with a current commercial quad.

The efficiency of a large propellor at low rotation speed is well known.
So I wondered about scaling this concept up to 60 inches.
Also, the link to a single (as in only one sycamore type) blade, gives anecdotal evidence that there is greater efficiency to be gained.

I'd welcome any thoughts on how the 'sine wave modulation synchronised with rotor position' might be achieved in software, at only 500 rpm or so it may be possible without completely redesigning a flight controller/brushless motor driver.

A Swashplateless MAV: Thrust, Roll, Pitch, and Yaw from Only Two Motors (1 min 34 sec)

https://www.modlabupenn.org/wp-conte..._ICRA_2015.pdf
Single Rotor Blade Helicopter. (Experiment) (8 min 32 sec)
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Sep 19, 2019, 09:09 AM
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https://www.kickstarter.com/projects...l-flying-robot
If you compare this extensively researched and developed (but failed) kickstarter project ,with my bi-copter based on KK2 and Openaero VTOL, which in contrast obviously cost me only a few peanuts...although I did difficult high efficiency Blue Wonder rewinds?
My success in creating a stable machine is really mainly thanks to Dan and his incredibly flexible software...unfortuneatly any updraft over terrain means I can't descend vertically, which I have not been able to resolve. Of course it's no consolation to rotate back to plane flight and return to base. The timelapse is then however ruined.
The 'Fleye' kickstarter had vanes to vector thrust.
With the little information they made available, plus a pixie demo assembly video, the design looks like there is only a single rotor motor and blade?
The shroud is a pointless gimmick, there are very specific circumstances when a duct will provide overall weight and efficiency advantage. Cockerell's hovercraft for example, basically zero flow and therefore no drag penalty from the duct curved inlet. I suspect also, that it felt a bit safer than a pit into which one could step, to be instantly liquidised.
Like our ubiquitous multi/quadcopter, most design is conservative and attached to a connection bias. If it works, build on refining it.
The slow blade rotation of a large single rotor may have a lower induced vibration frequency. More difficult to damp out? But anticipated and therefore actively counteracted, possibly.
But the 'Fleye' gives a mediocre 5.4g/w efficiency.
My bi-copter is around 10g/w, with 6 inch props.
I should be able to do at least 20g/w with a custom light weight 30 inch single rotor prop and a geared Blue Wonder.
A quick calculation using my scales to get an AUW 425g, gives an hour flight, with 2P x 1000mA 3s battery.
I have a lot of experience using things like polypropylene straws to make geodetic structures and airframes for example, rigid yet crash proof and very light.
Servos and vanes, or satellite rotors?With a bias introduced to counterbalance the main rotor torque?
I am hoping the accelerometer and gyro sensors can react quickly enough to provide that function.
Any thoughts welcome.


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