What is a MultiCopter and How Does it Work
A multicopter is a UAV whose motion is controlled by speeding or slowing downward thrusting motor/propeller units.
- A MultiCopter is one of the simplest powered aerial vehicles imaginable: A bunch of fans pointing at the ground which push you up.
- MultiCopters are completely aerodynamically unstable and absolutely require computer control for stable flight.
- As a result, MultiCopters are entirely Fly by Wire systems and if the computer isn’t working, you aren’t flying.
- The QuadCopter shown above is the simplest type of multicopter, with each opposite pair of motors spinning in opposite directions.
- This allows the copter to turn (Yaw) right or left by speeding up one pair and slowing the other pair of motors.
- Horizontal motion is accomplished by speeding up motors (increasing thrust) on one side and reducing it on the other.
- This causes the copter to tilt (Roll or Pitch) in the desired direction of motion and thrust is re-equalized.
- The angle of the copter is generally representative of it’s speed in that direction.
- To hover the copter compensates for disturbances (gusts of wind) by tilting automatically against the direction of the disturbance.
- In order to accomplish this, the copter has electronic gyros which sense level in 3 dimensions.
- In addition, they may also have electronic accelerometers which sense displacement in 3 dimensions.
- Altitude control or change is accomplished by speeding up or slowing down all motors at the same time.
Significant Design Considerations for MultiCopters
- A MultiCopter is a highly stressed system so it is important that all components are carefully matched to its capability.
- Projected weight, performance, flight time and payload all require careful balancing to achieve a good result.
- A high performance, light weight QuadCopter has different needs than a heavy lift, camera carrying Hex or OctoCopter.
- Frame size and weight, motor/prop requirements, power (battery) needs, and payload are important considerations.
- A small QuadCopter is ideal to learn to fly on. They are easy to fly, light, tough, relatively safe and survive mishaps well.
- A big Hex or Octo with a camera rig is seriously expensive, much more hazardous and is inappropriate to learn on.
- It will also tend to break much more destructively (and expensively) than a relatively light and unencumbered QuadCopter.
Good Choice To Start Not So Much!