In-flight Refueling

The first documented scheme for in-flight refueling came from a young Russian aviator named Alexander de Seversky. His father owned a plane and taught him to fly when he was in his early teens. At the age of 21 Seversky, flying for Russia in World War I, attacked a German destroyer. He got shot down before he could drop his bombs, which exploded when his plane crashed. Somehow Seversky survived, but he lost a leg. Less than a year later, wearing a wooden leg, he returned to military aviation, and he soon downed 13 German planes.

In 1917, now 23, Seversky proposed a method for extending flight: One plane could carry extra fuel and deliver it to another through a hose. After the Revolution, Russia’s new Bolshevik government sent him to the United States to study aircraft design, and he stayed there when political developments made his return perilous. He got a job as an aeronautical engineer for the U.S. War Department and was awarded the world’s first patent for air-to-air refueling, which proposed to provide “large fuel tankers … to supply fuel to pursuit ships while in flight.”

Seversky went on to a distinguished career in airplane design and achieved perhaps his greatest fame as the author of the influential 1942 book Victory Through Air Power. He never put his refueling plan in action, though, and other aviators concocted ideas of their own. In 1918 Lt. Godfrey L. Cabot, a U.S. Navy Reserve pilot, dreamed up the idea of placing cans of gasoline on floating platforms in the ocean and picking them up with a hook trailing from a flying plane, much as express trains of the day snatched mailbags. Although Cabot became proficient at picking up cans with this technique, no one ever used it for refueling.

On November 21, 1921, a completely different method was tried. Frank Hawks (who a year earlier had taken Amelia Earhart on her first flight, and who would go on to set numerous speed records as a promotional pilot for the Texas Company, which later became Texaco) flew his Lincoln Standard biplane over Long Beach, California. Wesley May, a barnstorming wing walker, crawled up onto its top wing. With a five-gallon can of gasoline strapped to his back, May started walking toward the edge of the right wing. Meanwhile, Earl Daugherty, perhaps America’s greatest stunt pilot, eased his Curtiss Jenny just above the Lincoln. When Daugherty got his lower left wing within range, May reached up and grabbed a loop on its lower edge. Then Daugherty eased away, with May and his gas can hanging below. May climbed up onto the lower wing and eventually poured the gasoline into Daugherty’s tank.

In-flight refueling of a less strenuous sort attracted the attention of some military pilots. In World War I, Lt. John Richter had complained about having to return repeatedly to base to get more fuel during the St. Mihiel offensive in 1918. In 1923 he flew patrols along the Mexican border with Capt. Lowell Smith. Both men grumbled about the abbreviated flights and seemingly constant refueling. Smith suggested refueling the planes in midair and got the go-ahead to try it. Richter turned out to be a good choice to try out the new equipment because he had tested locomotives for the Santa Fe Railroad. For his part, Smith had flown in cross-country races as an official representative of the Army Air Service.

Smith and Richter turned a De Havilland DH-4 two-seater into a tanker by installing a 40-foot hose strengthened with steel cable. To refuel, a crewman in the tanker would toss the heavy hose overboard, and a crewman in another DH-4 flying nearby would try to grab it as it whipped in the wind. Richter even designed a hand pump to put suction on the gas tank in the receiver.

On April 20, 1923, Lt. Virgil Hines and Lt. Frank Seifert, flying the tanker, came in above and behind Smith and Richter and dangled a hose from the cockpit. (The tanker approached from behind to keep the hose from tangling in the receiver’s propeller.) Imagine that someone is whipping the hose at a gas station as you try to grab it and that the hose keeps flailing as you put the nozzle in the tank and fill up. That’s what Smith and Richter faced on that flight. Somehow one of them managed to grab the hose and hold on to it, and the two planes kept contact for 40 minutes in this tethered arrangement, though they passed no fuel.

The basic technique seemed to work, so on June 27, 1923, the same teams transferred fuel between planes. On the first contact, 25 gallons of gasoline were transferred. The receiving plane kept flying until it needed fuel again, and a second hookup gave it 50 gallons. Overall, the receiving plane stayed airborne for 6 hours and 38 minutes. Beginning the next day, the receiver flew for 23 hours and 48 minutes nonstop, taking on 308 gallons of gasoline. On August 27 and 28, with 14 refuelings, Smith and Richter stayed aloft for 37 hours and 15 minutes.

The future of in-flight refueling looked promising until November 18, 1923, when some aviators attempted refueling over Kelly Field in San Antonio, Texas, as part of a carnival exhibition. The hose from the tanker caught in the propeller of the receiver, and the tanker crashed, killing Lt. P. T. Wagner. His death ended American experiments with refueling for several years.

In the fall of 1928 a group of Army Air Service officers decided to try again. They modified a Fokker C-2 for aerial refueling and called it Question Mark because no one knew how long it could stay in the air. An impressive accomplishment for duration aloft had been set in June 1928 by the Belgian air force, which used refueling to keep a De Havilland biplane in the air for more than 60 hours. (As the aviation historian Richard K. Smith has written, “Given the minuscule size of Belgium … the purpose of this operation is unclear.”)

The tests would demand reliable tankers, which were created by modifying a pair of Douglas C-1s. Each was given two 150-gallon fuel tanks and a trapdoor to drop out a 50-foot hose. (The same method was also used to lower and raise baskets containing food, oil, clothing, messages, and tools and parts for repairs.) To refuel, the tanker crew dangled the hose near Question Mark while the two planes flew at 80 miles per hour with as little as 15 feet separating them. One of Question Mark’s crew members would stick his head and shoulders out of a hatch in the roof, behind the wing, and grab the fuel hose. Then he would manhandle it through the hole and line it up with the tank’s opening.

During the design stages, crew members had feared that pulling the fuel hose through the air could create static electricity and cause a spark when the nozzle touched the fuel tank’s opening. So the designers wrapped a copper wire around the nozzle and mounted a copper plate near the opening in Question Mark. Before refueling, a member of the receiving crew touched the hose to the copper plate to discharge any static. The project started at Boiling Field, in Washington, D.C., but winter arrived before the tests could get under way, so the group moved to Rockwell Field, near San Diego, in midDecember.

Keeping Question Mark airborne required communication between it and the tanker, but airborne radio was still in its infancy, so the team devised an array of cumbersome techniques for keeping in touch. For air-to-air signals between the planes, the crew members wrote messages on blackboards or used hand signals during the day; at night they used flashlight signals or attached written messages to the end of the gasoline hose. When members of the ground crew needed to communicate with Question Mark, they wrote on the side of the tanker. To send a message to the ground, the Question Mark crew put it in a weighted bag and dropped it.

After months of preparation on both coasts, Question Mark was ready for testing. On January 1, 1929, it took off from Lot Angeles Metropolitan Airport, in Van Nuys, California, with Maj. Carl Spatz (who in 1937 would change the spelling of his last name to Spaatz to encourage the proper pronunciation, “Spots”), Capt. Ira Eaker, Lt. Harry Halverson, Lt. Elwood Quesada, and Sgt. R. W. Hooe aboard. It was quite an illustrious crew. All except Hooe eventually became generals, with Spaatz serving as the Air Force’s first chief of staff and Quesada heading the Federal Aviation Agency. Capt. Ross Hoyt, flying one of the refueling planes, also went on to become a general, and today the Brig. Gen. Ross Hoyt Award is given annually to the Air Force’s top refueling crew.

The team planned to refuel over the Rose Bowl, in Pasadena, where Georgia Tech and California were playing. (This was the game in which Roy (“Wrong Way”) Riegels, a California lineman, picked up a fumble and ran it toward his own end zone, resulting in a safety that provided the eventual margin in Tech’s 8-7 victory.) With the hose stretched between the planes and fuel flowing, Eaker held Question Mark steady. Suddenly turbulence forced the planes apart, and the hose swung wildly inside Question Mark. Gushing fuel soaked Spaatz. Eaker jumped up from the controls, turned the plane over to Quesada, and told him to head out to sea. Eaker and the others stripped Spaatz and rubbed him down with lubricating oil to keep the fuel from burning his skin. Spaatz had no intention of ending the flight, so the planes flew out to sea and finished transferring fuel there.

Later refuelings were less eventful, and once the crew settled into a routine, they were able to receive fuel every few hours. During all refuelings, crewmen were required to wear parachutes, so Spaatz, covered only in lubricating oil, put on a chute and got to work with the rest of them. Question Mark stayed aloft for 150 hours and 40 minutes, flying an oval course between Van Nuys and San Diego. During the flight the two tankers pumped more than 5,000 gallons of fuel in 43 transfers.

Private pilots took up the challenge of surpassing Question Mark’s feat. By July 1929 the record for duration aloft was up to 420 hours and 17 minutes. A year later it was 647 hours and 28 minutes. And in July 1935 a pair of brothers, Fred and Algene Key, of Mississippi, set a record that still stands by keeping Ole Miss, a Curtiss Robin J-1, in the air for 653 hours and 34 minutes, more than 27 days.

The success of Question Mark’s flight also kindled interest in applying in-flight refueling to commercial aviation. From August 15 through 20,1929, the Texas Company conducted a nonstop flight of a Buhl Airsedan CA-6 from Spokane, Washington, to New York City and back. That flight required 11 refueling, including one in a violent storm. Another refueling, over Miles City, Montana, took place without a regular tanker available. Local residents, alerted to the emergency by a dropped message, filled five-gallon milk cans with gasoline and sent them up in a plane, from which the cans were lowered with a rope onto the top of the Buhl’s fuselage. Despite, or perhaps because of, this experience, commercial airlines showed little interest in the prospect of in-flight refueling.

The U.S. military also stepped back from refueling technology in the 1930s. Strategists sought other ways to make planes fly farther, including low-drag steel monocoque skins instead of wood or fabric, larger fuel tanks (which could sometimes be jettisoned when empty), and more efficient engines. In-flight refueling research continued, however, in other countries, particularly Great Britain.

The technique still needed improvement. One weak link involved getting the hose from the tanker to the receiver; simply dangling a hose in the air seemed primitive even in the 1920s. After watching an aerial-refueling demonstration at the 1930 Chicago National Air Races, Lt. Richard Atcherley of Britain’s Royal Air Force thought he could do better, and he devised a new approach.

In Atcherley’s technique, the tanker trailed 300 feet of line with a grapnel hook at the end. The tanker flew in from behind, at an angle to the receiver, to hook the receiver’s 100-foot weighted line. The receiver then pulled in the tanker’s line, which was attached to a fuel hose. Atcherley also added an automatic coupling to the end of the hose, so the fuel line would open when the hose was connected to the receiver’s tank and close when it was disconnected.

Atcherley’s “crossover” method earned a patent in 1935. The patent was purchased by Flight Refuelling Limited, headed by Alan Cobham, who had previously been knighted for his work on civil aviation. The company took over Atcherley’s work, receiving support from Imperial Airways, which envisioned using refueling in its commercial flights.

By 1939 Flight Refuelling Limited had developed another technique. In this method the receiver pulled a weighted line with a grapnel hook at the end, while the tanker flew alongside and fired—somewhat like a whaling harpoon gun—its hooked line across the other to entangle the hooks. The tanker pulled in both lines, attached a hose, and released them. The receiver then pulled back the lines and the hose with a winch. As in previous methods, the fuel flowed under the power of gravity, requiring the tanker to fly higher than the receiver.

This technology had its first commercial success on August 5, 1939. On that day two Imperial Airways Short S-30 flying boats flew from England to the United States, refueling in the air twice—once over Ireland and once over Newfoundland—from Handley Page Harrow bomber transports. It was not a nonstop flight; in fact, both refuelings took place shortly after takeoffs. Refueling was necessary because the plane was carrying a heavy load of airmail and could not have gotten off the ground with a full tank of fuel. The flight went so well that Imperial Airways repeated it 15 times. Before this advance could change commercial travel, though, World War II ended these experiments.

Mike May. Gas Stations in the Sky. American Heritage. Spring 2004; Volume 19, Issue 4.

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