Contact | Advertising | Copyright & Disclaimer
Site map | About

Aerodynamic Forces in a Rotor System

- Advertisement -

We will now put everything we have discussed together and look at all of the aerodynamic forces involved with a rotating blade around a shaft. This is set out in the figure below. We will firstly consider the position of the airflow. It is the relative airflow which sets the angle of attack, which is in turn determined by the horizontal (as a result of rotor rotation) and vertical airspeeds, with the latter being the result of induced flow. Secondly, we will look at the forces which play a role. These are the two components of the airfoil's reaction force: lift and drag.

Aerodynamic forces in rotor system

We must now take an important step forwards in our line of reasoning if we are to take into account both the mechanical rotation around the shaft, and the torque that must be provided by the engine to power the rotorsystem. Another force we are interested in is the rotor's lift in the vertical direction (upwards). Formulated in another way, we are now interested in the horizontal and vertical force components which work on the rotating rotor, relative to the plane of rotation. This can easily be done by breaking the reaction force down into the desired components, instead of into the aerodynamic lift and drag elements. The two forces we are interested in are rotor thrust and rotor drag. These are defined as the force components orthogonal to the rotordisc (that is, 'straight up') and the force components parallel to the rotordisc. Rotor thrust defines the amount of vertical thrust (opposing the weigth of the helicopter). Rotor drag defines the amount of torque that the engine must provide to keep the system rotating. Note that the way we resolve the reaction force into its components is arbitrary from a mathematical point of view, and the way that we have chosen to do so is for engineering purposes (rotor thrust and rotor drag) instead of as a way to explain aerodynamic behaviour (lift and drag).

   Next topic > Rotordisc

Helicopter Theory (Paperback)

  • This enormous tome provides comprehensive and detailed coverage of every aspect of helicopter theory. The purpose of the book is to set out for the reader the engineering analyses required to enable the successful design of a rotorcraft. All relevant subjects, such as vertical flight, forward flight, performance, rotating systems, rotary wing dynamics, aerodynamics and aero elasticity, and stability and control are covered. They are explained at an in depth engineering level, always accompanied by accurate mathematical analyses. A good knowledge of mathematics and a degree in engineering are necessary, as these topics are dealt with extensively throughout the text.
  • 1089 pages.

Principles of Helicopter Aerodynamics (Cambridge Aerospace Series) (Hardback)

  • Modern treatment of the aerodynamic principles of helicopters and rotating-wing vertical lift aircraft
  • Uses mathematics throughout the text
  • Concepts are derived from basic enginering principals
  • 864 pages
- Advertisements -



Do you want to comment this topic?

Log In |
|
|
|
or
|
|
|
|
|
(Email address will not be displayed with the comment.)

Name

Email

Enter the above code here:
Can't read? Try different words.


HeliStart is authored by Peter Goossens.


Best Sellers

1: (Book) Cyclic and Collective
2: (Book) Principles of Helicopter Flight
3: Microsoft FSX Steam Edition
4: Logitech Extreme 3D Pro Joystick
5: Saitek Pro Flight Rudder Pedals

[ Log In ]