Drones

Flowcopter's ultra-long range hydraulic drone is lifting serious weight

Flowcopter's ultra-long range ...
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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This unique heavy-lift UAV out of Edinburgh promises to obliterate the power and range of electric drones using a Rotax engine and bent-axis hydraulic motors similar to those used on huge tree harvesters. It's now lifting 95 kg (210 lb) in testing.

Flowcopter promises an extraordinary 900 km (560 miles) of range and more than six hours of endurance, as well as a huge 150 kg (330 lb) max payload. It's built for an ultra-long range niche, particularly targeted at making deliveries to super-remote settlements and offshore oil rigs, as well as extended search and rescue missions and long-endurance agricultural use.

These use cases simply can't be filled with all-electric powertrains – the specific energy in lithium-ion batteries pales in comparison to what fossil fuels can deliver. But combustion engines aren't well suited to delivering the near-instant torque adjustments required to balance a multicopter in the air.

Flowcopter's solution is to run a Rotax aviation engine through a digital displacement pump that can quickly and precisely regulate pressure out to low-cost, high-torque hydraulic motors driving each propeller. Fossil fuel endurance meets very quick torque adjustments – and these bent-axis hydraulic systems are already well-established for use in some extremely tough environments, such as John Deere's mammoth tree harvesters and Holt's Eraser stump grinders.

How do they perform? Well, the power is certainly there. Flowcopter has released a bunch of test videos in recent months, all on ground tethers and catch ropes, showing this big ol' Bessie stacked up with an alleged 95 kg of weightlifting plates and holding a hover. Check it out:

Lifting 95 kg of attached weights

Stability-wise, it seems the digital displacement pump is capable of doing the job – in a wind-free warehouse, at least. It certainly doesn't seem as steady as some of the larger eVTOLs we've seen flying, but it's unclear at this stage whether this is more to do with flight control software or the displacement pump lagging a little behind the action. Heck, there's a chance it might be on fully manual control at this stage, so we'll wait until we see some prototypes that are closer to a final product.

Flying on fossil fuel would seem to make this thing a bit of a dinosaur before it's even born, but in truth, aircraft like this can definitely play a part in carbon reduction efforts. The long-range Flowcopter isn't launching into a vacuum; a lot of its targeted missions are currently being flown by helicopters. This kind of thing could get some chopper jobs done using far less fuel. That reduces overall emissions, as well as risk to human pilots and operating costs. So while it's not perfect, it's at least a step forward.

Source: Flowcopter

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15 comments
15 comments
EH
So what is this "Digital Displacement® pump"? Basically, digitally controlled solenoid valves with variable timing of opening and closing allow making the pump's flow independent of the engine's RPM. See: https://fluidpowerjournal.com/digital-displacement-pumps/ for diagrams. I had never heard of these, but had long thought the Digital Displacement® pump's inventor, Prof. Stephen Salter, was a true genius, with many inventions in the renewable energy field.
paul314
Could you do something similar with fuel cells, or is the cost and weight still prohibitive? The efficiency is definitely there.
michael_dowling
You could use biofuel for this thing,which would fix it's pollution problem.
Chunk Applegrabber
Can I equip it with a harness and use it as a helicopter? Yes.

SHOULD I equip it with a harness and use it as a helicopter? No.

WOULD I? Hell, yes.
jerryd
Not a chance in hell this can do that with inefficient hydraulics combined with inefficient short high speed rotors. It can't carry enough gas to go anywhere near that far and the payload.
Another is why have computer controlled balancing when the far more efficient way using 2 large slow turning simple counter rotors above are dynamically stable and will just hang out having until told where to go, no computer needed or wanted.
Such a craft with a gas engine of 20hp could do this. One with less flew a human on 12hp 60 miles in 2000 as an ultralight aircraft. Without the weight rule limitation, easily do 600 miles with 200lb cargo.
Should be the basis for E-VTOLs too.
Expanded Viewpoint
They still haven't changed their lifting system from two blade props to ducted fans using carbon fiber for the fans and ducts. That will cut way down on the noise factor as well as increase their lift to weight ratio. Turbo fan jet engines use multiple blades for a reason!! And get rid of those hoses too! The pressure drop through them at high flow rates is just killing the efficiency of the whole thing! Friction goes up as a square of the speed, so using gently radiused bends in polished hard lines will cut down on those losses. Do they use a gyro to stabilize it or bubble levels? Are any real engineers involved in building this thing??
TedTheJackal
The main advantage of quad rotors is the simplicity of a brushless electric power train. If you're going to have a hydraulic system with a single IC engine it seems like you should just go with a single coaxial rotor. You probably get higher power/weight, higher efficiency, and fewer or at least less catastrophic failure points. But it's an interesting concept.
clay
"Flying on fossil fuel would seem to make this thing a bit of a dinosaur before it's even born"

This is a bit of a flawed perspective. We have not (yet) even arrived at the point where lift/delivery drones are ubiquitous, let alone have we passed that point on the curve. It seems the path forward is to use all energy methods to move this kind of transport ahead... and then the market can start dialing in "transition" technologies such as hybrids.. This will provide a smooth transition to economically and environmentally viable practical civil UAV transport ecosystem.
SBinSFO
Perhaps I'm missing something, but why isn't the drive train for this monster modeled after that of a hybrid automobile? I.e., a fossil-fuel-powered internal-combustion engine drives a generator that in turn provides AC or DC electrical power to the electronic speed controller and four (or N) servo motors that spin the propellers (throw in a small Li* battery and then the energy harvested from regenerative braking could be used to extend the flight time and range of the drone!). This would be a far simpler and modular implementation than all of this fussy hydraulic gear, and I'd wager it would weigh less, too.
Katerina Cokonis
To make it eco friendly and have adequate range the options are biofuels, hydrogen synfuels, green hydrogen, liquid hydrogen.
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