Aircraft radio telephony transmitter, 1915.
© Science Museum / Science & Society Picture Library
A radio telephony transmitter for use with aircraft, with a round valve and microphone. World War I saw the first attempts at installing radio communication equipment on aircraft, as the advantages of ground to air communication as well as between aircraft were obvious. Observation aircraft could direct the aim of artillery, as well as reporting enemy troop movements. Previously the only means of communication between pilots and with the ground involved hand signals and flags.