5 ms·

Not sure how to say this without sounding snarky, but how is 200kg cargo capacity over 40km "heavy lift"? That barely qualifies as ultralight for helicopters.

• post_break 5y ago
  Maybe because it doesn't require a helicopter pilot? You could run it 24x7 possibly autonomous to deliver specified goods. Heavy lift is also relative. 20mph on a bicycle is fast, 20mph in a car is slow.
  • greentissue 5y ago
    couldn't they focus on developed an autonomous/robotic helicopter rather then a drone? I don't think it can run 24x7 since it needs to refuel/recharge.
• Robotbeat 5y ago
  It definitely is heavy lift as far as drones are concerned. But I am disappointed that there has been so few drones trying to go in this direction that 200kg is considered “heavy.” (You can make arguments that the multi rotor approach has lower maintenance needs than swashplate-based conventional helicopters, besides the use of electricity instead of hydrocarbons… these all potentially allow lower operating costs. And the higher pitch sound of multi rotors travels less far than low frequency of helicopter blades.)
  • idiotsecant 5y ago
    It's not just maintenance issues - it's fundamental aerodynamics. Efficiency scales with the diameter of the rotor in rotary wing aircraft. Larger rotors are more efficient. In a helicopter you lose a bit of that efficiency from the tail rotor, but past a certain size helicopters are always going to be more efficient, until you get the size regime that materials drive all designs to become multi-rotor. It seems like maybe there is a niche for very large fixed-pitch propeller vehicles like quadrotors but at that scale why stick with fixed pitch at all? You could still have variable pitch rotors with variable speed drivers and get the best of both worlds, like a Kaplan turbine in hydraulics, but in reverse.
    • nradov 5y ago
      Single rotor designs remain efficient to a rather large size regime. The largest helicopter in operational use today is the Mil Mi-26 which has only a single rotor. The prototype Mil V-12 was a little larger and had two rotors but was not successful.
      • idiotsecant 5y ago
        That is indeed a very big main rotor. I wonder what the material limitations are on rotor length?
        • blacksmith_tb 5y ago
          Not an aerospace engineer, but my instinct is that spinning larger and larger rotors at the speeds needed to provide lift would likely become an issue before material strength, though obviously it's a consideration also.
      • Robotbeat 5y ago
        In part that’s because combustion engines scale down extremely poorly (they lose efficiency like mad… a micro turbine gets like 5% efficiency whereas a full sized turbine gets upward of 30%) and have high complexity. They’re also difficult to throttle on command with high responsiveness (hence the swashplate). Electric motors are far better suited to distributed lift concepts. That’s a huge reason why existing vertical lift doesn’t use multiple rotors. Electric motors using high energy magnets, modern solid state power controllers, and modern batteries are only just now becoming available & only now are they starting to impact the aviation trade space.
    • Robotbeat 5y ago
      That's kind of a misconception. You can use a whole bunch of smaller rotors to have nearly the same efficiency as a single rotor of the same diameter (okay fine there are also Reynolds Number effects from going smaller, but not as important in this context). The difference is roughly the packing ratio of circles, about 90%. VoloDrone takes this approach.
• deleted 5y ago
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