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