Calspan Test Pilot Brian Ernisse is back in his F22 for one

Calspan Test Pilot Brian Ernisse is back in his F-22 for one more flight test sortie. He decides to overfly the UB North Campus to give the Aerospace Engineering students, an airshow He decides to demonstrate the supercruise\" portion of the flight envelope at Mach 2.5 So as not to break any windows or irritate the neighbors, he climbs to an altitude 10,000ft above the campus.T he students look up to see him approaching. they hear nothing. How far past the campus is Mr. Ernisse When they hear the jet for the first time?

Solution

Solution:                   

Velocity of sound in air is 1125.33 ft/sec.

Mach 2.5 = 2813.32 ft/sec.

When Mr. Ernisse is flying 10000 ft above the campus the sound generated from aircraft needs to travel 10000 ft to reach the ground.

Hence time required for sound to reach ground will be: 10000ft/ Velocity of sound (ft/sec)

i.e. 10000/1125.33=8.88 sec

Students will listen aircraft’s sound after 8.88 sec of Mr. Ernisse passing the campus and during these 8.88 sec Mr. Ernisse will further fly with the speed of Mach 2.5

Distance covered in 8.88 sec is: 8.88*Velocity of aircraft (Mach 2.5): 8.88*2813.32=25004.78ft

Hence Mr. Ernisse will be 25004.78ft past the campus when students hear the sound of aircraft first time.