For any of those who have ever seen a helicopter, you likely know that it has a tail rotor, or some form of outlet (in the case of a NOTAR-Equipped aircraft) at the rear of the tail boom, in order to counter the main rotor’s torque. But what, exactly, does this do?
Well, the tail rotor (and we’ll focus on that, since NOTAR aircraft are far and few between) acts like a ‘stop’, to prevent the body of the aircraft from turning in opposite direction of the main rotorhead. The pitch of the rotor blades is controlled by (generally) anti-torque pedals installed in the floor of the cockpit. Using these, you can adjust the pitch (angle) of the rotor blades, and thus control the direction of their thrust. By doing so, it cause the tail boom to move in the direction you desire, turning the aircraft.
So why is a tail rotor essential? Well, if you don’t have one, your helicopter body would spin wildly as an opposite reaction to the main rotor spinning in the opposite direction. Generally, helicopter that spin wildly don’t make it very far towards their destination. On the plus side, however, if you happen to bring some fruit salad along, you’ll have a nice smoothie when you’re through, as you’ll be spinning around like a turbine powered blender!
The pedals inside most helicopters are fairly straightforward to operate: push the right pedal forward, and the tail will scoot left, causing the aircraft to turn right. Pushing the left pedal forward causes the opposite effect. The controls are similar on NOTAR-equipped helicopters, except that instead of controlling the pitch of the propeller, it controls the direction of thrust nozzles built into the tail boom.
The only helicopters that do NOT have a rear-mounted anti-torque system are those with tandem rotor heads and dual rotor heads. Tandem rotor helicopter platforms have the two rotors (on the same mast) rotating in opposite directions, which counters the torque generated by the opposite rotor. However, these helicopters STILL have anti-torque petals, to control the direction of the helicopters movement in flight.
Each and every helicopter, although designs do vary, needs some means to counter the torque created by the main rotor head. This is a basic law of physics: each action has a separate and equal opposite reaction. So if you want your helicopter to fly normally, by sure to verify it has a functioning tail rotor, coaxial rotor, or thrust nozzles system to ensure you can control the torque generated by the main rotor. Alternatively, if you find yourself with a means to counter the main rotor’s thrust, you could sell tickets to what’s just become among the most expensive amusement rides ever created; a sort of ‘spinning teacups’ from hell.
(No Anti-Torque System (Tail Rotor) = Tea Cups from Hell)