Bristol Type 138A

The Type 138A was purpose-built for record-breaking high-altitude flights, which were the object of intensive research and considerable national rivalry in the 1930s.
It was commissioned by Britain’s Air Ministry,  which turned to the Bristol Aeroplane Company because its engines Had powered many of the aircraft used in previous attempts on the world altitude record.
Designed by Frank S. Barnwell for routine flights at heights exceeding 50,000ft, the Type 138A was a lightweight, wooden monoplane
with a fixed undercarriage and an enclosed cockpit. Like all aircraft intended for such work, it had wings of generous span.
Its Pegasus radial engine was equipped with two superchargers, the second of which came into operation above 35,000ft.
On 28 September 1936 Squadron Leader F.R.D. Swain, wearing a primitive pressure suit and helmet, took the Type 138A up to 49,967ft – the first time an aeroplane had flown above 49,213ft. Running short of oxygen during his descent, be broke a window
in his helmet. The new altitude record lasted until May 1937, when an Italian Caproni Ca.161 biplane reached 51,362ft. In response,  flight Lieutenant M.J. Adam took off from Farnborough in a modified 138A in June and pushed the record up to 53,937ft.