Angle of Attack(AoA) - Is the angle between the chord line of the rotors and the relative wind acting on the rotors.
Horizontal airflow(translational lift) - Airflow which is moving across or horizontally over the rotor disk, it is due to forward movement or wind.
Up flow - Air coming vertically up though the rotors.
Relative wind - With respect to the airfoil relative wind is the combination of all air acting on the airfoil: induced airflow, horizontal airflow, rotational velocity, and up flow.
Rotational Velocity - Relative wind acting horizontally on the rotors due to their rotation.
The combination of rotational velocity(horizontal) airflow and induced airflow(vertical) create relative wind.
Increasing induced airflow decreases AoA by changing the relative wind to flow slightly more vertically into the rotors.Decreasing induced airflow increases the AoA.
Something similar happens when the rotational velocity is increased, it causes induced airflow to have less of an effect on the total relative wind. This creates a higher AoA.
Horizontal airflow(translation lift) is created by either the helicopter accelerating into forward flight or wind blowing towards the helicopter, this has the same effect as increasing rotational velocity, it increases horizontal movement into the rotors and decreases induced airflow, both of which increase AoA. Induced airflow decreases because clean air is moving into the rotor disc freely.
Next newsletter with compare this theory to ETL and ground effect.
Resources
Company website
For some information about LEA’s flight school, maintenance facility, commercial operations, or aircraft sales, visit the company website.
Here is a Link to FlyBend.com
Facebook
Also Flow Leading Edge on Facebook
Here is a Link to the Facebook page.
NTSB Accident Report
For a search query of reports accidents to the NTSB
Here is a Link to ntsb.gov
R22 Preflight written instructions, here is a good Link with pictures and text about a R22 preflight.
And this is the sublink that goes to and miscellaneous page with some really good information about the helicopter and components that aren't identified on the preflight check list.
