Bristol
91 Brownie

Bristol's entrants in the 1924 and 1926 Light Aircraft Competitions held at Lympne.
Bristol 91 Brownie prototype The Bristol 91 Brownie prototype in its initial configuration.

 

The Bristol Aeroplane Company Bristol Brownie was a light sports two-seat monoplane, designed in accordance with the rules of the Air Council 1924 light aircraft competition. These light weight machines with low installed power offered surprisingly good performance.

 

Previously, the competition rules meant that Bristol had not built an aircraft to compete as engines were restricted to below 750 cc, rendering the Bristol Cherub unsuitable.  

 

However, the 1924 regulations saw the maximum capacity increased to 1,000 cc which allowed Bristol Chief Designer Frank Barnwell to explore studies in alternative wood and metal designs. These subsequently gained 'Board Approval' for the initial production of 2 aircraft, although this was quickly followed by a third.

 

The first aircraft flew in the hands of Test Pilot Cyril Unwins on 6th August 1924 (G-EBJK) which was nicknamed 'Jack'. It was immediately followed by the second aircraft (G-EBJL) this time nicknamed 'Jill, in September that year. A third aircraft (G-EBJM), nicknamed 'Jim',also flew soon after.

 

Bristol 91 Brownie second aircraft G-EBJL G-EBJL, the second Bristol Brownie photographed in September 1924.

 

The Bristol Brownie had an all steel tube fuselage and was flown with both wooden and two different types of metal wing of differing span. Trials at Lympne took place during late September and early October 1924 with Uwins taking an overall second prize of £1,000, plus a further £500 for the best take-off and landing.

 

'Jim' (G-EBJM) was later flown in single seat configuration with the shorter span metal wing for speed competitions.

 

Bristol 91 Brownie G-EBJM single seat The third Bristol 91 Brownie G-EBJM in single seat configuration with short span wings.

 

Meanwhile, 'Jack' (G-EBJK) was subsequently returned to Filton for modifications in December 1925, where it was fitted with the newly developed 36 hp Cherub III mounted slightly lower in the fuselage.  The top longerons were also curved more downwards to improve the view from the rear cockpit. Additionally, the fuel tank was enlarged and it was fitted with new metal wings, giving it a span of 37 ft 7 in (11.45 m). In this configuration it was designated as the  Bristol Type 91A.

 

After further trials at Martlesham Heath, the Bristol Type 91A was again returned to Filton where the engine mounting was lowered further and it was fitted with a Fairey-Reed propeller. A curved decking was also added to the rear fuselage as was an enlarged horn-balanced rudder and a new undercarriage.

 

In this form and designated as the Type 91B (or Brownie II) it competed in the 1926 Lympne Trials, taking the third place prize of £500.

 

All-in-all, the Bristol Brownie offered excellent performance, handling and economy on its limited power. Unfortunately, it was insufficiently robust, lacking in the power-reserves required for a truly practical machine. Like the other entrants in the 1924 competition, the Bristol Brownie proved fairly impractical machines for the private owner.

 

What was actually required was being subsequently demonstrated by the De Havilland DH60 Moth  It had been designed purely to meet the customer needs without being subject to the constraints of these somewhat artificial competitions and their impractical restrictions  with which Bristol felt compelled to comply.

 

Specification


  Type 91 Type 91A, 91B Brownie II
Powerplant        One 32 hp Bristol Cherub I                       One 36 hp Bristol Cherub III
Span 34ft 7in (wood) G-EBJK 36ft 7in G-EBJL (metal wing version 1), or
30ft 7in G-EBJM (metal wing (version 2), in single seat configuration), or
37ft 7in (new metal wings fitted to G-EBJK when modified to Type 91A and 91B)
Maximum Weight 870 lb, 720 lb single seat 1,010lb (G-EBJK, 91B Brownie II)
Capacity  Pilot and passenger Pilot and passenger, or pilot only (G-EBJM)
Maximum Speed 70 mph 78 mph (125 mph)
Range 100 miles 125 miles

 

Variants & Numbers built


Three only        
G-EBJK (Type 91, later Type 91B with revised nose shape, new rudder and 36hp Cherub III); G-EBJL (Type 91A); G-EBJM (Type 91A, also flown as single seater with no change in designation)
 

Survivors


No examples survive.