High Altitude Flashcards
Mach speed is the:
Ratio of TAS to the local speed of sound
The speed of sound is directly related to temperature, as temperature decreases
speed of sound decreases
The effect of compressibility is an aid to the creation of ______, until the airstream of the wing’s surface reaches the ________________. When this happens, compressibility effects being to appear due to the creation of shock waves.
Lift, speed of sound.
Risks of operating near speed of sound:
Airflow separation, loss of longitudinal stability, buffeting, Mach Tuck
Shock Wave =
air flowing over the wing crosses a massive pressure boundary, which sucks energy out of the airflow, the air can lose a lot of energy and it separates from the wing.
Critical Mach =
the speed at which a shock wave first forms on the aircraft. Speed varies with aircraft weight, altitude, %CG and load factor
Dutch Roll =
one wing getting ahead of the other which may be brought on by turbulence or poor rudder control. One wing gets ahead of the other, that wing is moving faster and therefore, creates more lift and climbs. As the wing creates more lift, the wing creates more drag, eventually the upward wing will be pulled back, causing the airplane to slip. The low wing then accelerates, creates more lift and climbs, then it creates more drag and the oscillation is repeated.
Coffin Corner =
as you increase altitude the low speed stall increases and high speed stall decreases
Limiting Mach =
maximum operating airspeed in relation to the speed of sound
A decrease in critical mach corresponds to a _____ in weight
increase
A decrease in critical mach corresponds to a _____ in load factor
increase
A decrease in critical mach corresponds to a more _____ CG
forward
A decrease in critical mach corresponds to a _____ in altitude
increase
What are the design characteristics of high altitude airplanes?
High stall speeds, higher touchdown speeds, rapid increase in drag at high angles of attack during turns.
