Bristol Brownie

Bristol Aeroplane Company

Industry	Aerospace
Founded	June 1, 1910 (1910-06-01)
Headquarters	United Kingdom
Products	Aircraft

The Bristol Type 91 Brownie was a lightweight sports aeroplane developed in the United Kingdom by the Bristol Aeroplane Company during 1924. It featured a low-wing cantilever monoplane design with a conventional layout and fixed tailskid landing gear. The aircraft accommodated the pilot and passenger in tandem open cockpits. In October 1924, it secured the £1,000 award for second place at the Lympne light aircraft trials.

Design

Bristol did not enter an aircraft in the 1923 Lympne light aircraft trials, which restricted engines to 750 cc or less, rendering Bristol’s own Cherub engine unsuitable. For the 1924 competition, rules were amended to allow engines up to 1,100 cc, prompting Frank Barnwell to begin designing a contender early that year. He prepared proposals for both wooden and metal airframes, and after evaluation, Bristol’s board approved the construction of two aircraft on 4 February, followed by a third on 5 May.

While all three shared a similar fuselage structure composed of wire-braced high-tensile steel tubing, they featured three distinct wing configurations for experimental comparison: one wooden wing spanning 34 ft 7 in (10.54 m), and two metal wings—a larger all-steel wing measuring 36 ft 7 in (11.15 m) and a smaller high-speed variant at 30 ft 7 in (9.32 m) combining steel and duralumin. Compliance with competition regulations required the wings to be easily detachable and the aircraft to have dual controls installed.

The trio were registered on 14 July as G-EBJK, G-EBJL, and G-EBJM, receiving the names Jack, Jill, and Jim respectively. The first to fly was G-EBJK with wooden wings on 6 August, piloted by Cyril Uwins. Its excellent performance led to immediate subsequent flights by Barnwell himself, followed by joint flights with Uwins. G-EBJL, equipped with the larger metal wings, took to the air on 22 September, while G-EBJM—configured as a single-seater with an extended range fuel tank and smaller metal wings—completed its maiden flight on 4 September.

All three aircraft participated in the trials held from 27 September to 4 October. Uwins piloted 'JK to achieve second place in the main competition. 'JL was withdrawn due to aileron flutter issues before it could compete under pilot T.W. Campbell. Campbell flew 'JM to secure third place in the Grosvenor Cup race, maintaining an average speed exceeding 70 mph.

Development

Following the Lympne trials, the aircraft 'JK' and 'JL' were sent to Martlesham Heath for assessment as primary trainers. However, they failed to sufficiently impress the Air Ministry, which declined to provide funding for further development.

In December 1925, G-EBJK was brought back to Filton for alterations. It received the newly introduced 36 hp Cherub III engine, repositioned slightly lower within the fuselage. The upper longerons were reshaped with a more pronounced downward curve to enhance visibility from the rear cockpit. The fuel tank capacity was increased, and new metal wings were installed, extending the wingspan to 37 ft 7 in (11.45 m). This updated version was designated as the Type 91A.

After additional testing at Martlesham, the aircraft returned once more to Filton, where the engine mount was lowered further and equipped with a Fairey-Reed duralumin propeller. A curved decking was added to the rear fuselage, alongside an enlarged horn-balanced rudder and a redesigned undercarriage incorporating rubber shock absorbers. This iteration became known as the Type 91 B or Brownie II. In this configuration, the aircraft participated in the 1926 Lympne trials, where pilot Uwins secured third place along with a £500 prize.

Specifications (Brownie I, wooden wing)

File:Bristol Brownie 3-view NACA-TM-289.jpg

Three-view illustration of the Bristol Brownie from NACA-TM-289