Flight of the "Question Mark"

The U.S. Air Force website has updated their feature on the Question Mark, a three-engine Fokker C-2 which played a major role in the development of air refueling: Flight of the 'Question Mark'.

The flight, born from the ingenuity of Airmen through their experiences in World War I, lasted from Jan. 1-7, 1929; a total of 150 hours and 40 minutes. The crew flew a 110-mile racetrack from Santa Monica, Calif., to San Diego, Calif.... During the flight, they made 43 contacts with the tanker aircraft. Each contact lasted about seven and a half minutes, with the two aircraft about 15 to 20 feet apart. Day-time contacts took place at an altitude between 2,000 and 3,000 feet, and the 10 night-time contacts took place between 5,000 and 7,000 feet.

These historic flights were not the U.S. Army Air Corps' first attempts at aerial refuelling:

Air refueling... had humble beginnings. The first attempts were in 1921 with the employment of five-gallon gas cans when a U.S. Navy lieutenant, in the back of a Huff-Daland HD-4, used a grappling hook to snag a gas can from a float in the Potomac River. In another attempt, a wing walker with a gas can strapped to his back, climbed from an airborne Lincoln Standard to a Curtiss JN-4 to pour gas into the aircraft's tank.
While these two publicity stunts deserve mention, the first air-to-air refueling using a gravity-flow hose occurred in 1923. Earlier that year, the Army Air Service had equipped two de Haviland DH-4Bs with in-flight hoses. After installation, testing and preparation, the Army Air Service was ready to put it to use. On June 27, one of the DH-4s flew a six-hour-and-38-minute flight that included two air refuelings.