- #1
Himal kharel
- 79
- 0
Why doesn't helicopter turn in opposite direction of rotation of propeller?
Helicopter Propeller Rotation: Explained
- Thread starter Himal kharel
- Start date
-
- Tags
- Rotation
In summary: This is usually done with a tail rotor, which creates a moment of inertia to oppose the main rotor's torque.
- #2
rcgldr
Homework Helper
- 8,889
- 650
For single main rotor helicopters, there's a small rotor or exhaust port at the tail for most helicopters. This equalizes the torque from the main rotor, but then you end up with a net side force that requires the helicopter to lean a bit to one side to compensate for the side force.
- #3
chrisbaird
- 610
- 5
Himal kharel said:
Great question. The answer is that without extra features, the helicopter does turn in the opposite direction. As rcgldr pointed out, a tail rotor pushing in the opposite direction can cancel out the torque. Another interesting approach is to have two main propellers rotating in opposite directions so that the torque cancels, and then you don't need a tail rotor. The two propellers can be side by side, inter-meshed, in tandem, or coaxial (notice no tail rotors):
- #4
Himal kharel
- 79
- 0
if the engine is just at cg then no torque will be produced. then why are extra blades necessary?
- #5
russ_watters
Mentor
- 23,522
- 10,868
Incorrect. Why do you think that it is?Himal kharel said:
- #6
mikeph
- 1,235
- 18
Without any air the rotor blades could spin without the body having a torque, I believe. What causes the body to spin is either a change in the speed of rotation (conservation of angular momentum / Newton's 3rd law means the body must rotate the opposite way) or air resistance, whose opposition to the fast motion of the blades imparts on the aircraft a torque in the opposite direction of the blade's rotation. This is transferred through the mast to the fuselage, which begins to spin.I'm not entirely sure but I think from that, the reason the body would rotate without a tail rotor is because the air resistance opposing rotation of the blades > the air resistance opposing rotation of the body.
- #7
A.T.
Science Advisor
- 12,571
- 3,717
Yes, there is an aerodynamic torque on the main rotor, opposite to it's rotation. This external torque needs to be balanced by some other external torque on the system.MikeyW said:
FAQ: Helicopter Propeller Rotation: Explained
What is the purpose of helicopter propeller rotation?
The purpose of helicopter propeller rotation is to generate lift and thrust to keep the helicopter in the air. As the propeller blades rotate, they create an area of low pressure above the rotor and high pressure below, which results in lift. The rotation also creates a force known as torque, which counteracts the torque from the engine and keeps the helicopter from spinning out of control.
How do helicopter propellers rotate?
Helicopter propellers rotate due to the power generated by the engine. The engine turns the main rotor shaft, which is connected to the main rotor gearbox. The gearbox then transfers power to the main rotor blades, causing them to rotate. The pitch of the blades can also be adjusted to increase or decrease the amount of lift and thrust generated.
What is the difference between clockwise and counterclockwise rotation?
The direction of rotation for helicopter propellers can be either clockwise or counterclockwise. This is determined by the rotation of the main rotor blades, which can be either right-hand or left-hand. The direction of rotation affects the handling of the helicopter and is determined by the design and purpose of the aircraft.
How does helicopter propeller rotation affect flight performance?
Helicopter propeller rotation plays a crucial role in flight performance. The speed and direction of rotation can affect the amount of lift and thrust generated, as well as the stability and maneuverability of the helicopter. Proper rotation and pitch control are essential for safe and efficient flight.
Can helicopter propeller rotation be reversed?
Yes, helicopter propeller rotation can be reversed by changing the pitch of the blades. This is known as reverse thrust, and it is used to slow down or stop the helicopter during landing. Some helicopters also have the ability to reverse the direction of rotation of the main rotor blades, which is known as reverse rotation.