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The wikipedia Quadcopter entry provides some details about its flight control:


enter image description here

Hovering or altitude adjustement.


enter image description here

Pitch or roll adjustment.


enter image description here

Yaw adjustement.


The following post "Quadcopter flight modes beyond traditional aircraft?" raised to my attention that it had other flight modes apart from those of fixed wing aircraft but I am not so sure with respect to conventional rotorcraft.

Question:

My assumption is that the quadcopter can be flown using conventional helicopter flight control inputs (cyclic, collective, anti-torque, throttle), am I right or is it really another beast with its very own flight control inputs?

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  • $\begingroup$ I have not the specific knowledge to make a proper answer, but quadrocopter are much more similar to fixed wings rather than helicopters. (among those controls you listed, they have only one throttle per rotor, just for starters) $\endgroup$ – Federico Jun 22 '14 at 19:55
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    $\begingroup$ Given clever avionics and a masochistic pilot, any FBW aircraft could theoretically be flown using a cyclic, collective and throttle. We no longer have to adapt the pilot to crude mechanical linkages but can design the interface to suit the pilot and the mission. $\endgroup$ – RedGrittyBrick Jun 23 '14 at 8:51
  • $\begingroup$ Quadcopters are only ever going to be controlled by computer. They are practical for models and small scale unmanned vehicles, but not full scale aircraft carrying people. See why haven't quadcopters been scaled up yet. $\endgroup$ – Jan Hudec Jun 23 '14 at 9:13
  • $\begingroup$ @jan-hudec: I have posted this answer to the question you refered to (scaling up of multi/quadcopter). $\endgroup$ – menjaraz Jun 23 '14 at 9:48
  • $\begingroup$ @redgrittybrick: I expected the cyclic, collective, anti-torque and throttle to expose the usual facade hiding the complexity under the hood: the interface as you name it. Can you please expand a little and post it as an answer? $\endgroup$ – menjaraz Jun 23 '14 at 10:07
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As commented, a quadcopter is generally flown by a computer. Given command inputs, the computer controls the speed of the four rotors, as shown in the images included in the question. The four rotors give the quadcopter a wide range of maneuverability. This is why quadcopters are currently used in many research applications. They can simulate conventional fixed-wing flight, helicopter flight, or something completely different.

A quadcopter could certainly be flown with conventional helicopter controls. The four rotors allow it to be controlled by a cyclic, and the differential rotor torque allows it to be controlled by the anti-torque controls. However, unlike most helicopters, most quadcopters have fixed-pitch rotors. This is probably mainly due to size and cost constraints. The small size of quadcopters, combined with the lift being distributed among four rotors, allows each rotor to be smaller and much more resposive with RPM than a large rotor. This means that instead of collective and throttle, most quadcopters will only have throttle. Controlling the speed if the individual rotors is the end-result of their control algorithms.

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Yes a quadcopter can be flown with the four conventional helicopter type controls, which need to be translated into rotor speeds by a control loop, as follows:

  • Cyclic fwd/aft: fwd rotor spins up, aft rotor spins down equally. Rotor speeds equalise again when the stick angle has been reached.
  • Cyclic lateral: left rotor spins up, right rotor spins down equally. Rotor speeds equalise again when the stick angle has been reached.
  • Collective: all rotors spin up.
  • Anti-torque: clockwise rotors spin up, anti-clock spin down proportionally

Throttle is not required as a separate control, it is effectively the rotor speed which is used in the other four controls.

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