How to calculate the Gust Envelope? I am trying to draw the V-n Diagram for a small aircraft I built, but I am stuck in the gust envelope part. I know how it is supposed to look. However, I am having a hard time calculating it. I would like to know (1) why it's composed of four lines; and (2) how to find the slope of each line. So far, I have these three equations:







Also, (3) why do these equations describe the gust envelope, and (4) what each variable in the equations stands for?
The gust envelope is four lines overlaid on the flight envelope, usually the plus/minus of maximum gust at design cruising speed (Vc) and half maximum gust at maximum speed (Vd) as required by the certifying authority. This is usually +-50ft/sec (15.2m/sec) and +-25ft/sec (7.6m/sec).




n is the normal acceleration in a sharp edged gust
K is the tailplane gust alleviation factor. In a canard this is an aggravation factor.
u is the airplane mass ratio


The source contains examples of how the lines are calculated. The following information (defined) is required: