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Not an expert, but I'd guess quadcopters are much easier to pilot. You press a button and they go that way. Taking off and landing on wings is very difficult in

Not an expert, but I'd guess quadcopters are much easier to pilot. You press a button and they go that way. Taking off and landing on wings is very difficult in comparison, requires more space, more facilities, more organization.

alkonaut 6y ago
But they have tiny wings (arms) and if they were airfoil shaped then it would give some lift in straight and level flight. Then at start/landing/low speed, they would just do nothing. Perhaps the air is so turbulent around the wings due to the propellers that wings just don't get any airflow to create lift, or would need to be much longer to be out of the way of the propellers, that it's not worth it?
- mikepurvis 6y ago
  Adding foldable wings would be a massive complexity and weight increase relative to the standard scheme which pretty much boils down to 4 motors + an IMU, with the rotors being the only moving parts. The closest thing in the real world to the hybrid that you describe would probably be the tiltrotor, where the same engines which supply lift can turn 90 degrees to become forward thrusters on wings: https://en.wikipedia.org/wiki/Tiltrotor https://en.wikipedia.org/wiki/Tiltrotor
  - alkonaut 6y ago
    I don’t mean foldable I just mean airfoil shaped cross sections that still fit within the normal “wingspan” of the multirotor. Amazon have made at least two designs, one that flies “tilted” and uses the boundary ring as wings, another with more separate wings and forward propulsion Version 1: https://techcrunch.com/2020/08/31/amazons-prime-air-drone-delivery-fleet-gains-faa-approval-for-trial-commercial-flights/ https://techcrunch.com/2020/08/31/amazons-prime-air-drone-de... Version 2: https://www.amazon.jobs/en/teams/prime-air https://www.amazon.jobs/en/teams/prime-air
nuccy 6y ago
Actually it is not easier at all, the complexity is obscured by an onboard computer, which constantly helps to keep position, not to flip upside down and lose control completely. By applying differential thrust on different propellers it executes commands from operator to tilt and rotate. If the computer fails, operator, even with a direct control of the propellers, will not be able to maintain a stable flight. From aerodynamic standpoint planes are much easier to pilot (all but military, same story with computers for better maneuverability) since they are designed to be inherently stable. So if all power is lost and you still have control of aerodynamic surfaces, there is not problem to land a plane after planning for some tens or even hundreds of kilometers (depends on initial altitude). This is obviously not the case with quadropters, loss of a single propeller leads to complete loss of control.
- mikepurvis 6y ago
  It leads to loss of six-dimensional control, though interestingly you can still maintain five-dimensional control (losing yaw) with only three or even just two props, see demonstration from ETH Zurich: https://www.youtube.com/watch?v=t369aSInq-E https://www.youtube.com/watch?v=t369aSInq-E
  - nuccy 6y ago
    Yes, indeed, though this seems to be an experimental drone. Most common commercially available DJI drones fall if single motor or propeller fails, though in future they may gain such functionality, which would be great for safety. A nice example of a different approach is a variable angle of attack propellers which are driven by a single motor [1]. See after 0:52 and 7:13. In case battery is dead since all the propellers are synchronized they auto-rotate and stabilize the drone (near the earth the pilot activates the motor just to land softly, but likely similar effect can be reached by properly adjusting the angle of propellers in proper time, like in case of auto-rotation landing for helicopters). [1] https://youtu.be/TnGhEInTXYc?t=52 https://youtu.be/TnGhEInTXYc?t=52 (this video was posted below by @jcims)
    - mikepurvis 6y ago

alkonaut 6y ago

But they have tiny wings (arms) and if they were airfoil shaped then it would give some lift in straight and level flight. Then at start/landing/low speed, they would just do nothing. Perhaps the air is so turbulent around the wings due to the propellers that wings just don't get any airflow to create lift, or would need to be much longer to be out of the way of the propellers, that it's not worth it?

mikepurvis 6y ago
Adding foldable wings would be a massive complexity and weight increase relative to the standard scheme which pretty much boils down to 4 motors + an IMU, with the rotors being the only moving parts. The closest thing in the real world to the hybrid that you describe would probably be the tiltrotor, where the same engines which supply lift can turn 90 degrees to become forward thrusters on wings: https://en.wikipedia.org/wiki/Tiltrotor https://en.wikipedia.org/wiki/Tiltrotor
- alkonaut 6y ago
  I don’t mean foldable I just mean airfoil shaped cross sections that still fit within the normal “wingspan” of the multirotor. Amazon have made at least two designs, one that flies “tilted” and uses the boundary ring as wings, another with more separate wings and forward propulsion Version 1: https://techcrunch.com/2020/08/31/amazons-prime-air-drone-delivery-fleet-gains-faa-approval-for-trial-commercial-flights/ https://techcrunch.com/2020/08/31/amazons-prime-air-drone-de... Version 2: https://www.amazon.jobs/en/teams/prime-air https://www.amazon.jobs/en/teams/prime-air

nuccy 6y ago

Actually it is not easier at all, the complexity is obscured by an onboard computer, which constantly helps to keep position, not to flip upside down and lose control completely. By applying differential thrust on different propellers it executes commands from operator to tilt and rotate. If the computer fails, operator, even with a direct control of the propellers, will not be able to maintain a stable flight. From aerodynamic standpoint planes are much easier to pilot (all but military, same story with computers for better maneuverability) since they are designed to be inherently stable. So if all power is lost and you still have control of aerodynamic surfaces, there is not problem to land a plane after planning for some tens or even hundreds of kilometers (depends on initial altitude). This is obviously not the case with quadropters, loss of a single propeller leads to complete loss of control.

mikepurvis 6y ago
It leads to loss of six-dimensional control, though interestingly you can still maintain five-dimensional control (losing yaw) with only three or even just two props, see demonstration from ETH Zurich: https://www.youtube.com/watch?v=t369aSInq-E https://www.youtube.com/watch?v=t369aSInq-E
- nuccy 6y ago
  Yes, indeed, though this seems to be an experimental drone. Most common commercially available DJI drones fall if single motor or propeller fails, though in future they may gain such functionality, which would be great for safety. A nice example of a different approach is a variable angle of attack propellers which are driven by a single motor [1]. See after 0:52 and 7:13. In case battery is dead since all the propellers are synchronized they auto-rotate and stabilize the drone (near the earth the pilot activates the motor just to land softly, but likely similar effect can be reached by properly adjusting the angle of propellers in proper time, like in case of auto-rotation landing for helicopters). [1] https://youtu.be/TnGhEInTXYc?t=52 https://youtu.be/TnGhEInTXYc?t=52 (this video was posted below by @jcims)
  - mikepurvis 6y ago