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  • Q811303

    Hi

    Can anyone shed any light on why the old Vs used in this question is 1 rather than the 2 stated in the question?

    Cheers
    Kat

  • #2
    This is a particularly nasty question.

    We are using the stalling equation here simply to discover the load factor at which the aircraft will stall at the new, reduced speed of 1.2 Vs. The speed it will stall at in 1g flight is 1 times Vs, so it's this figure that gets changed when LF increases.

    The question describes how the load factor increases when we are hit by a gust at a speed of 2Vs. This increase is caused by an updraft that changes the relative airflow and increases the angle of attack. Flying as slowly as 1.2Vs, we will already have a high angle of attack, and we want to know if that same updraft will increase it beyond critical alpha.

    And it does. The theory says that the gust would give us 1.72g. But, in practice, we will stall long before we get to that figure.

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