1 Introduction Flashcards
What is dynamic aeroelasticity?
Dynamic Aeroelasticity is the oscillatory effects of the interaction between aerodynamic, inertia and elastic forces for a flexible structure.
(Pic 1)
What is static aeroelasticity?
The nonoscillatory effects of aerodynamic forces interacting with elastic forces in the flexible aircraft structure.
What are some negatives if STATIC aeroelasticity is too high?
- Potential reduction in control effectiveness and possible control reversal.
- Potential divergence (e.g. twist increases without limit)
What are some negatives if DYNAMIC aeroelasticity is too high?
Flutter the unfavourable coupling between two or more vibration modes leading to potential instability (extraction of energy from
airstream)
What is the centre of pressure?
The point that the aerodynamic forces act around.
It moves as the angle changes
3D Lift equation
2D Lift Equation
Where c is the cord length
2D Drag Equation
Where c is the chord length
3D Drag Equation
3D Pitching Moment Equation
extra *c, compared to the other
2D Pitching Moment Equation
Reynolds number equation
u = velocity
D = characteristic length
Air Density Equation
How does pitching moment coefficient at the aerodynamic centre change with incidence or CL?
Cmx=Cm0
Pitching moment coefficient does not change with angle.
What is the 2D CL graph equation?
What is a1?
The gradient of the 2D CL curve
What is a0?
Zero lift angle of attack
What is
It is the moment coefficient at the zero lift condition.
What is the lift on a strip (dL) equation?
What is aw?
The 3D coefficient lift curve slope
When is the coefficient of moments = to zero?
At the aerodynamic centre (ac)
What is the Total Lift from the strip theory?
Acts at quarter chord
What’s the relationship between moment and lift coefficients below stall?
Equation to get the CM at a random place:
