What was the world's first single-turboprop aircraft to fly?

Short answer

The second prototype of the Boulton Paul Balliol: it flew on 17 May 1948 with the intended Armstrong Siddeley Mamba turboprop and became the world's first single-engined turboprop aircraft to fly. The first prototype had flown on 30 May 1947 with a Bristol Mercury 30 radial of 820 hp (611 kW).

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

What was the world's first single-turboprop aircraft to fly?

Boulton Paul Balliol T2 3 view silhouette

An advanced trainer for the T.7/45

In March 1945 the Air Ministry issued specification T.7/45, seeking a new advanced trainer. In late August 1945 Boulton Paul received an order from the Air Ministry for a batch of four prototypes, which were to carry the Rolls-Royce Dart turboprop. In August 1946 a larger order arrived, for 20 pre-production aircraft, ten with the Dart and ten with the Armstrong Siddeley Mamba turboprop; delays in the Dart's development meant the prototypes ended up fitted with the Mamba.

From the Mercury radial to the Mamba turboprop

Since the Mamba was not ready to fly when the first prototype was completed, it carried a Bristol Mercury 30 radial of 820 hp (611 kW) for its early test flights. So equipped, it first flew on 30 May 1947, after initial landing gear problems were resolved during ground testing. The second prototype, with the intended Mamba, flew on 17 May 1948 and became the world's first single-engined turboprop aircraft to fly.

The Merlin for the production aircraft

On 10 July 1948 the first Merlin-powered Balliol, designated Balliol T.2, made its first flight. The production aircraft carried the Rolls-Royce Merlin, while several prototypes and pre-production aircraft used alternative powerplants such as the Rolls-Royce Dart and Armstrong Siddeley Mamba turboprops.