High Alt Flight

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  1. Why is EAS important when considering High Alt Flight
    Its used to calculate aerodynamic force produced
  2. Why is TAS important
    Because it is the speed of a body relative to the undisturbed airflow around it
  3. Why does stability reduce at altitude
    As altitude increases, TAS increases and effectively reduces AOA. The consequent reduction in lift results in less stability
  4. Why is damping in roll effect reduced at high altitude
    Down going wing AOA is reduced with the higher TAS so damping in roll effect is reduced ie less stability
  5. Why is longitudinal stability reduced at altitude (and draw a picture to explain)
    If the aircraft is disturbed about tis lateral axis the tailplane generates a restoring force. As altitude and TAS increase the effective AOA reduces so less restoring force is generated and overall les stability
  6. Why does thrust reduce with increasing TAS
    increasing TAS reduces AOA of a prop
  7. Explain how temp, density, and speed effect thrust when alt is increased
    • Temp decreases, which increases density so thrust increases
    • Density decreases, thrust decreases however this is offset partly by the decrease in temp
    • Spped increases therefore thrust decreases but RAM effect increases thrust so they cancel out

    Overall a jet engine is considered to provide constant thrust with increasing altitude
  8. Why does CL decrease with increasing altitude
    • the change in reynolds number
    • The decreasing local speed of sound
  9. As altitude increases, at a constant EAS, whtat happens to Mach and TAS
    • TAS increases
    • Mach increases more
  10. With an increase in altitude, directional stability decreases, how do designers overcome this
    • Bigger vertical stabiliser
    • Or increase the number of vertical stabilisers
Card Set
High Alt Flight
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