Rotary (Coriolis) force on the example of helicopter
Swivel (or Coriolis) forces occur in all cases where the body simultaneously participating in two movements, one of which is rotary (the body is transferred with the system) and one translational (body moves relative to the system). The relative movement should not be parallel to the axis of rotary motion, or rotary forces arise.
If we select a small section at the radius of the blade with a mass movement consider it, we see that the turning force must inevitably arise.
The peripheral velocity is tangential to the circumference of an element t. The magnitude of this rate does not undergo changes, but the changes in direction.
In addition, the mass m due to the stroke of the blade at an angle is still a relative stroke speed, which varies both in magnitude and direction. We already know that a wave of change in the velocity
in magnitude and direction takes place since that started a wave of first increased, then because of the reduction of the angle of attack of the blade is reduced, and when the blade moves to the position retreating, flapping stops (speed is 0), then start lowering the blade (speed changes direction ).
Changing the direction of the rate of stroke is also due to the fact that the mass at a stroke of his trajectory is a circle centered on the axis horizontal.
The appearance of the rotary acceleration can be explained as applying to an element of the blade energy conservation. In this particular case, the law will be formulated as the law of conservation of angular momentum. Under this law, the product of the angular velocity on the radius should be constant. Change the value of r (element blades approached (axis of rotation) must be accompanied by a change (the speed should increase). This increase in speed is the rotational acceleration.
Of course mechanics it is known that the magnitude of the acceleration is equal to twice the rotary angular velocity of the portable product of the relative speed of rotation (perpendicular to the axis of rotation)
It is the greater, the more turns of a rotor and the greater speed and flapping angle about a horizontal hinge.
Rotary acceleration corresponds to turning force equal to the product of mass and acceleration
For screws with other data, turning the power can reach several times greater.
When flapping up the force acting in the plane of rotation of the blade and pushes it forward (directed towards the rotation of the blade). When lowering, it is directed against the rotation of the blades, t. E. Inhibits its rotation.
Thus, during one rotation of the blade is experiencing double-load change in the plane of rotation, which inevitably leads to yaw the nose of the helicopter right to left and back.
Yaw of the helicopter would also contribute to the variable force of air resistance, tending the stronger, the less reject the blade in the direction opposite to the rotation.
Impermanence resistance forces during one revolution of the blade due to the same cause as the volatility of the lift, ie. E. A change in flow velocity and angle of attack of the blade. Advancing blade is experiencing more resistance than retreating.
- Aviation and literature
- A uniform
- Military aviation
- Civil Aviation
- Helpful information
- The calendar
- Aviation and music
- game air
- Plane Crash
- Aviation and cinema
- Educational establishments
- Author's articles
- Assemblies and units of air equipment
- The probability of catastrophes
- Online Timetable
- The calculation of the distance
Best in the world of aviation