The First Refueled Flights

Aerial refueling entered the world as a stunt with a fire hose and left the 1920s as a proven technique nobody in uniform wanted. Between the first hose contacts over San Diego in 1923 and the tanker force planned for the war against Japan, here is how the experiment worked, why endurance records buried the military lesson for twenty years, and what finally made the idea impossible to ignore.

A fire hose over San Diego

In June 1923, two Army Air Service DH-4B biplanes flew formation over Rockwell Field near San Diego while a hose carried gasoline from one airframe into the ordinary fuel filler of the other. Two months later the same crews stayed aloft more than 37 hours on nine contacts, passing 687 gallons of gasoline and 38 gallons of oil. That October, a DH-4 flew from Sumas, Washington to Tijuana, Mexico, refueling at Eugene and at Sacramento. England's Royal Aircraft Establishment and the French Armée de l'Air ran similar trials that year, to the same verdict: a stunt.

Why the Air Corps cared in 1928

Takeoff weight, not tank size, set the limit on range. Second Lieutenant Elwood Quesada learned the lesson in April 1928, nearly running dry on a rescue mission to Labrador. When two Belgian airmen, Louis Crooy and Victor Groenen, lifted the refueled endurance mark to more than 61 hours in June 1928, Quesada and a Marine Corps aviator from Anacostia drafted a plan to take the record back with a military purpose attached. Captain Ira Eaker pushed it up the chain, and Major General James Fechet and Assistant Secretary F. Trubee Davison approved on one condition: the flight had to demonstrate a military application, not a publicity stunt.

One transport, two tankers and a painted question mark

The receiver was a new Atlantic-Fokker C-2A, serial 28-120, a high-wing trimotor of 10,395 pounds gross on three 220 horsepower Wright engines. Mechanics at Middletown Air Depot cut a hatch in the roof behind the wing, added two 150-gallon tanks in the cabin, and built catwalks so Sergeant Roy Hooe could reach the engines in flight. Asked how long they expected to stay up, the crew answered that that was the question, and a question mark went on each side of the fuselage. Two Douglas C-1 biplanes from the World Cruiser line became the tankers, each with 300 gallons feeding a lead-weighted 50-foot fire hose. The Wikipedia article on the flight of the Question Mark holds the full day-by-day log.

How did fuel actually change airplanes?

If you have fought a garden hose at full pressure, you know the feeling. The tanker slid in from above and behind, holding 20 to 30 feet of vertical separation until it sat slightly ahead of the receiver, and both airplanes steadied at 80 mph while a third crewman reeled out the hose. Major Carl Spaatz, on a platform beneath the open hatch in rain gear and goggles, grounded the hose and set it in a sloped-floor bucket receptacle. Gasoline then flowed by gravity at 75 gallons per minute, in 100-gallon deliveries of about 90 seconds, while Hooe hand-pumped it forward to the wing tanks. No radio was installed, so the crews worked with flags, flares, flashlights, weighted message bags, and notes chalked on the black fuselages of escorting fighters, the blackboard planes. That open bucket is a long way from the probe and drogue coupling, whose valves stay shut until the probe locks in.

Six days over Los Angeles

Takeoff came at 7:26 am on New Year's Day 1929 from Van Nuys, with Eaker at the controls and only 100 gallons aboard to save weight. During a refueling early in the flight, turbulence tore the hose from the receptacle and drenched Spaatz in gasoline. Fearing chemical burns, he ordered the flight to continue anyway, shed his soaked clothing, and ran at least one later contact that way until replacements came up the rope. The lasting enemy was engine wear: the left engine lost power from the third day and quit on the afternoon of January 7, and the airplane came down from 5,000 feet to 2,550 before landing at 2:06 pm, 150 hours, 40 minutes and 14 seconds after takeoff. The totals ran to 37 refuelings, 5,660 gallons of gasoline and 245 gallons of oil, with twelve contacts at night.

Did any of it prove a military case?

Spaatz's report to Fechet called refueling safe and practical, said it made a bomber's radius almost unlimited, and left room for more bombs at takeoff. The War Department and the Air Corps then dropped the subject anyway. A May 1929 bomber demonstration over New York lost its tanker to icing and mud in Pennsylvania, and Eaker's September attempt in a Boeing mail plane ended in a crash landing near Salt Lake City. An official Air Force history later dismissed the endurance fashion as aeronautical flagpole sitting.

The endurance ladder the flight started

The records came fast, all on the same gravity hose:

• 1923: the Rockwell Field crews, more than 37 hours on nine contacts.
• 1928: Louis Crooy and Victor Groenen over Belgium, more than 61 hours.
• 1929: the Question Mark near Los Angeles, 150 hours and 40 minutes.
• 1930: the Hunter brothers over Chicago, 553 hours and 40 minutes on two Stinson Detroiters.
• 1935: Fred and Al Key in the Curtiss Robin Ole Miss, more than 27 days on 484 fuel transfers.

Nine civilian crews passed the Question Mark's figure in 1929 alone. The Key brothers flew with a spill-free nozzle designed by A. D. Hunter, the first real advance in the hardware; their record stands, and the airplane is displayed at the National Air and Space Museum.

Why the world waited until 1948

Interwar Britain came closest. The Royal Air Force wanted lighter takeoff weights to spare its grass airfields, tested refueling between 1930 and 1937, and then quit. Sir Alan Cobham, a long-distance pilot out of the Royal Flying Corps, founded Flight Refuelling Ltd in 1934; by 1938 his looped-hose system, on the same gravity principle as the Question Mark's hose, was fueling Short Empire flying boats. Between August and October 1939, Empire boats made sixteen Atlantic crossings, fifteen of them refueled in flight, before the war closed the trials. Avro Lincolns of Tiger Force were to have taken fuel from Lancaster tankers for long strikes against Japan, but the capture of Okinawa removed the need. Better engines, variable-pitch propellers and longer-ranging metal monoplanes made tankers look unnecessary; the war that followed then ran short of range for ferrying, antisubmarine and bombardment work. In January 1948, Spaatz, by then the first Chief of Staff of the United States Air Force, made aerial refueling the top strategic priority, and the first dedicated squadrons followed within months. To see what the British hose became once the commitment was real, follow the KB-29 and KC-97 conversions into the jet age.