when did he join the air force?
1923.
Frank Bladin
Bladin transferred from the Army to the Air Force in 1923
who is frank bladin? He was a senior commander in the Royal Australian Air Force (RAAF).
wiki:17720226
Frank Bladin [SEP] Introduction
Air Vice Marshal Francis Masson (Frank) Bladin, (26 August 1898 – 2 February 1978) was a senior commander in the Royal Australian Air Force (RAAF). Born in rural Victoria, he graduated from the Royal Military College, Duntroon, in 1920. Bladin transferred from the Army to the Air Force in 1923, and learned to fly at RAAF Point Cook, Victoria. He held training appointments before taking command of No. 1 Squadron in 1934. Quiet but authoritative, he was nicknamed "Dad" in tribute to the concern he displayed for the welfare of his personnel. Ranked wing commander at the outbreak of World War II, by September 1941 Bladin had been raised to temporary air commodore.