Explain the pitching moment coefficient (cm0) of a cambered aerofoil
For a cambered aerofoil, cm0 is usually negative (which means that for positive lift the centre of pressure lies behind the aerodynamic centre)
What happens to the compressibility and the a.c. at Mach numbers above 0.5 - 0.6?
- compressibility effects become important
- a.c. starts to move backwards, slowly at first, then quite rapidly when zones of supersonic flow appear on the aerofoil (transonic regime). In supersonic flow, the position of the a.c. tends to 50% of the chord.
Explain "Ground loads"
- for taxiing, take off ground roll, landing
- through landing gear (reduce loads to a level that can be absorbed without damage)
What parts of the A/C do the ground load conditions influence?
- design of the landing gear
- structure of the A/C
- attachment points
List some of the main load conditions to be considered according to airworthiness regulations.
- level landing condition
- lateral drift landing condition
- one-gear landing condition
- side load condition
- braked roll conditions
- forward acting horizontal load (during towing)
Explain "ultimate load"
The maximum load that the test specimen can withstand before the material fails.
What is the common unit of the "aircraft lift curve slope" [CLα]?
The shear and bending loads are independent of speed.