Aircraft

Flowcopter begins testing the world's first hydraulic multicopter

Flowcopter begins testing the ...
Flowcopter is beginning to flight-test the world's first hydraulically propelled drone
Flowcopter is beginning to flight-test the world's first hydraulically propelled drone
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Flowcopter is beginning to flight-test the world's first hydraulically propelled drone
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Flowcopter is beginning to flight-test the world's first hydraulically propelled drone
A combustion engine and digital displacement pump allow near-instant torque control, huge power and exceptional range
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A combustion engine and digital displacement pump allow near-instant torque control, huge power and exceptional range
The high-efficiency digital displacement pump can regulate flow between multiple hoses with fine control
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The high-efficiency digital displacement pump can regulate flow between multiple hoses with fine control
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Multicopters would be able to lift heavier loads and stay in the air longer if they could use a high-density power source like gasoline instead of low-density lithium batteries. But gasoline engines, with their weird, peaky torque curves, aren't nearly responsive enough to keep a multicopter balanced against rapidly changing winds.

We've seen a number of different ways of addressing this – one memorable idea that springs to mind from many years ago proposed running both electric and combustion motors together, directly on each propeller shaft, with the gas engine supplying more or less constant torque, and the electric motors kicking in when high-speed adjustments were needed.

Edinburgh's Flowcopter has a different solution entirely. Its heavy-lift cargo drones will run aviation-certified combustion engines, and these engines will drive Digital Displacement pumps repurposed from the off-road and industrial vehicle markets, to run hydraulic motors at the props.

These pumps are able to distribute and regulate hydraulic flow between a number of different outputs, under digital control, with the kinds of near-instant response times you need to balance a drone in flight. Each hydraulic motor will deliver up to an enormous 96 kW (129 hp) of power, while weighing just 5.5 kg (12 lb) and costing less than US$1,000 apiece. Flowcopter says "nothing electric comes even close."

A combustion engine and digital displacement pump allow near-instant torque control, huge power and exceptional range
A combustion engine and digital displacement pump allow near-instant torque control, huge power and exceptional range

The weight of the Digital Displacement pump, combustion engine and fuel system might be significant, but gasoline offers so much more usable energy per kilogram than lithium that the benefits will more than outweigh the drawbacks in Flowcopter's estimations. The company promises endurance up to 6 hours on a tank of gas, and range figures up to 900 km (560 miles), from a straight-up multicopter with no efficient winged flight mode. It'll be holding itself up on propeller power alone for all six of those hours. Payloads will be up to 150 kg for shorter missions.

Flowcopter has built a fairly raw-looking prototype – none of your fancy carbon fiber here, folks, it's a welded metal frame – and has been doing some tethered flight testing. It's a little on the wobbly side, as you'll see below, but it flies, and as the world's first hydraulic hybrid multicopter, that's an impressive achievement. It'll be interesting to see if this technology pans out into widespread use.

A-Frame Tethered Stability Testing

Source: Flowcopter

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9 comments
9 comments
paul314
Hydraulics tend to require a fair amount of maintenance, but then so do aviation-rated ICE engines.
Ron
Interesting concept, I always thought a fuel engine generating electric for brushless motors would be the final solution to cargo drones but this does show promise.
Expanded Viewpoint
Oh man, they're not really serious about all of this, are they? Transferring energy from point A to point B via hydraulics like that is so inefficient, that alone should put the kibosh on the whole thing. The losses from pumping fluids due to friction in the lines can be enormous! They'd be better off using wire ropes like an old school speedometer coming off of a multiple output gear box. And only two prop blades per motor? Come on, Man! They should be running an odd number of fan blades to cut down on noise and duct them to increase the efficiency factor. And use a gimbal type mount to vector the thrust by signal coming from a gyro. They need to go back to Aero Engineering 101.
noteugene
Wasn't it AMAZON a couple years ago who gave up on drone delivery? It was someone major. Whoever it was should reconsider drone configuration. (GO GAS).
niio
"Each hydraulic motor will deliver up to an enormous 96 kW (129 hp) of power"

Except that the gas engine that powers everything only puts out 140hp peak and the hydraulics might be 80% efficient, so sustained power delivered by each hydraulic motor will be less than 28hp.
Lamar Havard
...and it's not noisy at all! 😬
HokenPoke
Desperate last measures of an industry that has run it's course and still milking it from beyond the grave with their earth shattering oil platforms, rather turn the page while the competition is still fresh and focus on the next revolution, Electric. Because you have virtually unlimited funds. Really a no brainer if i was CEO.
EJ222
@HokenPoke Aviation is a whole different animal, you just cant get ICE range out of batteries yet.


That being said, fuel cells would work pretty well here, I think.
HokenPoke
@EJ222
Yes fuel cells is something that has great potential. I will say this. Short distance EVTOL travel is right now currently a viable commercial option with EVTOL's. So the start to focus on Electric powered vehicles for all companies should already become priority.