On this day 98 years ago the first air to air refuelling between two aircraft took place. Refuelling in the air had taken place before, but not via a hose, but with a fuel can. Already in November 1921, a wing walker walked across the wing of a Lincoln Standard mid-air and step across onto the wing of a Curtis JN-4 "Jenny" and emptied the can into the tank of the Jenny.
Flight endurance was limited by the fuel capacity of the aircraft of the time. To "fix" this, pilots at the Rockwell Field in San Diego (USA) developed a system using a hose to enable fuel to be transferred between two De Havilland DH-4B aircraft. On the 27th of June 1923, two De Havilland DH-4B aircraft took off. The first piloted by Virgil Hine and Frank Seifert and the second piloted by Lt. Lowell Smith and Lt John Richter.
The first aircraft lowered a hose mid-air to the second aircraft and fuel was transferred between two aircraft mid-air using a hose for the first time in aviation history. A few words on the De Havilland DH.4 aircraft that were used in this first air to air refuelling. The history of the DH.4 dates back to World War one and was the first British two-seat day-bomber that had a gunner to defend itself. The first flight of a DH.4 took place in August 1916 and entered frontline service over France on the 6th of March 1917. A total of 6295 DH,4 were built, 4846 were built in the USA by different manufacturers. A lot of variants were built in the United Kingdom, the United States and Russia, about 35 variants and sub-variants were developed, From a bomber, as originally designed to trainer, civilian and even ambulance aircraft. Also, different engines were used from Radial to the most used Rolls Royce Eagle VIII V12 engine. Specifications of the DH.4 with Rolls Royce Eagke VIII Engine:
Length: 30 ft 8 in (9.35 m)
Wingspan: 43 ft 4 in (13.21 m)
Height: 11 ft 0 in (3.35 m)
Wing area: 434 sq ft (40.3 m2)
Empty weight: 2,387 lb (1,083 kg)
Gross weight: 3,472 lb (1,575 kg)
Powerplant: 1 × Rolls-Royce Eagle VIII water-cooled V12 engine, 375 hp (280 kW)
Maximum speed: 143 mph (230 km/h, 124 kn) at sea level
Endurance: 3 hr 45 min
Service ceiling: 22,000 ft (6,700 m)
Time to altitude: 9 min to 10,000 ft (3,000 m)
Armament of the military version Guns: One fixed forward-firing .303 in (7.7 mm) Vickers machine gun, 1 or 2 .303 in (7.7 mm) Lewis guns on a Scarff ring
Bombs: 460 lb (210 kg) of bombs