In 1923, the United States Army (there was no U.S. Air Force at that time) set a
ID: 1559960 • Letter: I
Question
In 1923, the United States Army (there was no U.S. Air Force at that time) set a record for in-flight refueling of airplanes. Using two refueling planes, an Airco DH-4B biplane was able to remain in flight for 39 hours. During the flight, the refueling planes were able to air-transfer a total of 687 gallons of fuel to the plane in 9 refueling transfers. Assume that the refueling nozzle had a diameter of 1.45 inches and each refueling took 2.31 minutes to perform. Calculate the velocity of the fuel through the nozzle. Assume that the fuel filled the entire cross-sectional area of the nozzle.
Explanation / Answer
Amount of fuel = 687 gallons
= 687 x 0.133681 ft3
= 91.84 ft3
time taken t = 9 x 2.31 x 60 = 1247.4 s
flow rate = 91.84 / 1247.4 = 0.0736
diameter = 1.45inches
radius r = 1.45/2 = 0.725 inches
area A = pi.r2 = 3.14 x 0.725 x 0.725 = 1.65 sq.inch =1.65 x 0.00694444 =0.01145 sq.feet
velocity of the fuel through nozzle v = flow rate / area
= 0.0736 / 0.01145
=6.43ft/s or ( 6.43 x 0.3048m/s= 1.959864 m/s)