A 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 in testing.
Flowcopter promises an extraordinary 900 km of range and more than six hours of endurance, as well as a huge 150 kg 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: