Question

An F-15 supersonic fighter aircraft is in a rapid climb. At the instant it passes through a standard altitude of 25,000 ft, its time rate of change of altitude is 500 ft/sec, which by definition is the rate-of-climb. Corresponding to this rate-of-climb at 25,000 ft is a time rate of change of ambient pressure. Calculate this rate of change of pressure in units of pounds per square foot per second.

Answer 1

Here you want to calculate the dp/dt, to calculate this, the hydrostatic equation will work.

I e

dp = -pgdhg

Where rho and g both depend on h_{​​​​​​G}. Now, dividing the above equation with dt, we will get

dha = -p(hg)g(hg)

For the given data and using the above equation, the rate of change of pressure will be,

= -1.0663x10-3[slugs/ ft]*32.3[ft/s?]x500[ft/s] = -17.111b/ft²/s