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The public knows about drones, they're wrong in most
cases. What they're usually referring to is piloted hobby
grade through to semi-professional aircraft most often used
as camera platforms. The most common design for these is
the quadcopter, 4 brushless DC motors spinning propellers
ends of a rough X-shape with the batteries,
controllers, and radio gear in the middle. The position of
the propellers at the periphery makes them vulnerable to
damage whenever the quadcopter hits anything, which is
To solve this, we can do a quick re-design. The main body
in the center of the craft now contains a centrifugal
blower spinning about a vertical axis. The air intake is at
the top of the craft, air is compressed by the blower and
exhausted through 4 tubes in the familiar X-shape. At the
ends of the tubes, rotating nozzles direct the exhaust,
mainly they will be directing it downward for lift. Small
sliding valves can control air distribution to each of the 4
tubes and the rotating nozzles add additional control
The central blower, when accelerated/decelerated will
impart torque on the whole aircraft. This could be
countered by angling the nozzles at the end of the tubes.
The smarter way would be to have 2 motors driving two
concentric counter-rotating centrifugal blowers. By
controlling the two, changes in thrust can be made with no
net torque. Better yet, rotation of the craft can be
achieved by speeding up one blower and slowing the other
to cause torque with the same net thrust.
Because most of the force generated goes to opposing the
aircraft weight, there's no actual need to have it generated
at the ends of the X-shape, instead, a central exhaust
constituting 50-90% of the thrust would be more efficient,
and could perhaps be varied depending on the
The tube-nozzle design will have some pumping losses
associated but these can be offset. Larger motors are often
more efficient than multiple small motors per unit of
output. The tube nozzle system is used to good effect in
quieter helicopter tail rotors <link>. The advantages should
include lower noise, increased robustness and overall more
flying saucer-like aesthetic, combined with spooky
apparently reactionless rotation ability. The centrifugal
blower with axial input will essentially operate like one of
those fancy turbocharger compressors, all the work has
already been done there.
[bs0u0155, Nov 13 2018]
Avro Canada VZ-9 Avrocar
"...proved to have unresolved thrust and stability problems..." [8th of 7, Nov 13 2018]
Like this idea, except axial instead of centrifugal, engined instead of motored, and a jetpack instead of a drone. I haven't seen any updates in many years. [notexactly, Nov 14 2018]
Hackaday post on the same
Some more links, info, and arguing in the comments [notexactly, Nov 14 2018]
This is NOT a Propeller
Another type of small aircraft powered by a centrifugal blower, built by the late [Samm Sheperd] [notexactly, Nov 14 2018]
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||//A model Avrocar, then ? //
||Without the control problems, heat build-up and nuts triple
jet to central fan gearbox (I assume, can't actually see how
the fan was driven)
||The control problems will still be there, only they're probably manageable by contemporary electronic flight control systems.
||Although an Avrocar-like vehicle is probably practical now, it would still suffer from many of the same limitations as the original; very limited payload and endurance, low power-to-weight ratio, complexity, heat management, noise and vibration.
||It would actually be worse than a helicopter, an extremely difficult thing to achieve.
||//worse than a helicopter// you saw it here first.
||It strikes me that would-be flying car enthusiasts could
learn something from the world of ballooning.
||It is possible (and has been tried) for a complete idiot to tie
sufficient helium balloons to a deckchair to become
airborne - something that full-size-balloon balloonists
probably train for years to be able to do.
||So, translating this into drones, the best and safest way to
fly would be wearing a harness to which, say, 40-60
standard consumer-grade drones are tied. Just program
them all to stay in formation, and you're good to go. High
redundancy means that a few failed drones won't be
immediately fatal. Moreovermore, the noise from 40-60
small drones will be much less intense than from one vast
||Assuming that drones can be bought in bulk for £200 apiece,
that gives you a viable commuting option for less than the
cost of a modest car.
||//worse than a helicopter, an extremely difficult thing to
||Throw enough money at it and you can do anything. Did I
mention that I can make this stealth? I can also do sensor
fusion, and I've got this great idea about beginning the
manufacturing process before I've finished developing it...
||// Throw enough money at it and you can do anything. //
||Yes, that's the approach the Pentagon* has always used.
// Did I mention that I can make this stealth? //
||No; but the "black triangle" aircraft that fly out of Area 51 are already doing well in that technology, and we don't mean the F-117 either.
// wearing a harness to which, say, 40-60 standard consumer-grade drones are tied. //
||Some Scandiwegian nutjob has already done something very, very similar: a sort of "hoop skirt" built with many small drone motors.
*Not the common synonym for the U.S. Department of Defense, but the secret worldwide conspiracy run by an evil alliance of representatives of the Templars, Masons, Jesuits, Mafia, Illuminati and Mrs. Amelia Nugent, secretary of the Berkhampstead branch of the Women's Institute, who took a wrong turn and went through the door marked STAFF ONLY on the day that the secret password just happened to be "Blackcurrant jelly",
||Oddly, Amelia fits right in, and the other conspirators appreciate the marked improvement in the quality of the refreshments.
||// green foil triangles //
||That's not all ... the purple ones with the brazil nut in them are dead ringers for the B2 Spirit's engine intakes ...
||There's something going on that They don't want you to know about. Sinister stealth experiments with popular confectionery is only the start.