Old 16th Apr 2014, 10:54
  #91 (permalink)  
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Nor would you put it far below, as it would create an unnecessarily large tailfin.

After all V2 is also a minimum of 1.2Vs or 1.13VS1g. (Vs= 0.94 x Vs1g)

If you would aim for VMCA=Vsx1.09 V2min will meet both requirements. The tailfin would be minimum size and VMCA is larger then Vs at MTOW.

Now it all depends on how much VMCA changes with the decreasing weight of the aircraft. If its very little (almost constant) as you say then this is not a problem. If the change is massive then it needs to be changed in order to keep VMCA at a maximum of 1.2vs...
(Actually that is not true as the restriction is that it may not exceed 1.2VS at Mtow. It doesn't have this limitation at lower weights.)

Anyway I understand how VMCA can be below VS, I just don't think that when it is below the difference is massive. And it probably has more to do with the tailfin being designed for multiple variants of the same aircraft.

Last edited by 737Jock; 16th Apr 2014 at 11:28.
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