World Aviation in 1921

31 March
The Australian Air Force is formed from the Air Corps.

8 June
Experimentation with pressurised cabins begins at Wright Field in the USA, using a modified de Havilland DH4 aircraft.

21 July
United States Army MB2 biplane bombers bomb and sink the German battleship Ostfriesland with six 2,000 bombs. The aircraft were under the overall command of Brigadier General William 'Billy' Mitchell.

30 July
Flying a Caudron, Francois Durafour lands and takes off from Mont Blanc.

3 August
The first experiments in aerial crop dusting are carried out by Lieutenant John B. Macready on behalf of the Ohio Agricultural Experimental Station at Troy in Ohio. Using a Curtiss JN6 with a specially designed hopper fitted to the side of the fuselage 175 pounds of powdered arsenate of lead is distributed over 4,815 trees in an orchard.

The flight takes place at 20-35 feet and is accomplished in six nine-second discharges. Two days later C.R. Neillie, the Cleveland entomologist who had suggested the idea, reported "evidences of the wholesale destruction of insects were everywhere apparent." Less than 1% of the insects in the dusted area had survived.

10 August
The United States Navy Bureau of Aeronautics is formed.

13 August
The 'Royal' prefix granted to Australian Air Force.

23 September
Brigadier General William 'Billy' Mitchell provides another demonstration of aeroplane bombing against surface ships when aircraft under his command bomb and sink three unwanted United States Navy (USN) vessels, including the battleship USS Alabama.

12 November
Wesley May carries a can of fuel from one aircraft to another by climbing from one wing the other.

1 December
The United States Navy (USN) dirigible (steerable airship), Goodyear C7, makes its first flight.