In 1923 the United States Army there was no US Air Force at

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 1.65 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.

Solution

velocity = volumetric flow rate / area

= (687 gallons / 9 * 2.31 * 60 s) * 0.13368 / (pi/4)(1.65/12)²

v = 4.96 ft/s