Basic Aerodynamics and Stability

Presented by: Mr Jamie Presser

Topic:Overview of basic aerodynamics, flight controls and effects of Centre of Gravity on stability

Definition of Controlled Flight

Provide corrections Cause movement in the desired

direction

Controlled Flight is:

The ability to produce movements about the various axis that,

Aerodynamic Terms

Chord line: Line running from the leading edge

point of min radius to trailing edge

Chord: Length of Chord line

Aerodynamic Terms

Mean camber line: Line running half way between upper

and lower surface of aerofoilCamber: Distance between chord line and mean

camber line

Aerodynamic Terms

Angle of Attack Angle between chord line and Relative airflowCentre of Pressure (CoP) Point where all aerodynamic pressures can be

represented as a single vector

Angle

Relative Airflow

Chord Line

CoP

Bernoulli's TheoremGiven:

Total Pressure = P0

Static Pressure = P1

Dynamic Pressure = P2

P0 = P1 + P2

Bernoulli's Theorem

Lower static pressure

Higher static pressure

RestrictionAir Flow

P0 = P1 + P2

Primary Flight Controls

Aileron

Aileron

Rudder

Elevator

Thrust

Elevator

Primary Response = Change in Pitch Secondary Response = Change in Speed

Control movement

Ailerons

Primary Response = Roll Secondary Response = Yaw

Control Movement

Rudder

Primary Response = Yaw Secondary Response = Roll

Control Movement

Payload Aft of CoG

Payload

Naturally stable Unstable – Not recommended

Aircraft balanced with payload fitted – Nose down

tendency on release

Aircraft balanced without payload fitted – Unstable

until payload released

Naturally stable Unstable Not recommended

Aircraft balanced without payload fitted – Nose down

tendency until release

Aircraft balanced with payload fitted – Unstable when payload released

Payload

Payload Forward of CoG

Payload

Payload At CoG

No change on payload release

Ideal

Global Hawk Shadow

Reaper

Predator

Jindivick

HeronBoeing X-37

Fire Scout

Avitus - Petrel

Any Questions?