Today we’re looking at the Bristol Type 133, a single-seat, all-metal, low-wing monoplane
fighter from the mid 1930s…and probably one that many of you haven’t heard of.
It was one of several unlucky designs that tried to usher in the era of the sleek monoplane
fighter for the RAF, a task that was eventually completed by the Hawker Hurricane, and because
of the Hurricane’s success this innovative design, like that of the Gloster monoplane
fighter that we covered several months ago, is mostly ignored by aviation historians – both
amateur and professional.
To understand the history of the Bristol 133 we need to go back to 1930, and its predecessor:
the Bristol type 123.
In 1930 the biplane still reigned supreme, with the bulk of the RAF’s fighter force
being made up of the Armstrong Whitworth Siskin, and the Bristol Bulldog.
Though very capable aircraft themselves, the rapid advancements made in aircraft technology,
particularly powerplant design, meant that their modest top speeds were quickly deemed
obsolete.
The Bulldog could push to around 178mph on a good day, and the Siskin couldn’t even
reach 160.
Because of this, the Air Ministry issued specification F.7/30, which called for a high-performance
day-and-night interceptor fighter.
It required a design that was superior to existing fighters of the day in terms of range,
manoeuvrability, rate of climb, and service ceiling, and it required a top speed of no
less than 250mph.
Additionally the aircraft was to come with a two-way radio, it was to provide excellent
all-round visibility for the pilot, it had to have a low wing loading and be able to
land at speeds no greater than 50mph, and it was to be powered by the still experimental
steam-cooled variant of the Rolls Royce Kestrel IV, which would soon be renamed as the Rolls
Royce Goshawk.
The Air Ministry appreciated the complexity of their requirement, and when they invited
manufacturers to tender submissions in 1931 they set a generous three year deadline for
the production of prototypes.
Additionally, their invitation came with the promise of substantial production orders for
the winning aircraft, and those would had not succeeded would be given the opportunity
to submit more adventurous designs as a private venture as well.
In essence, it was the opportunity of the decade – one that would spawn several interesting
designs, as well as lead to the issuing of follow-up specifications that would lead to
the development of the RAFs fighter force that went into the second world war.
Not wishing to be left out, and despite being forced to using a competitor’s engine in
the design, the Bristol Aeroplane Company submitted their proposal in 1932.
In fact, they eventually proposed no less than four.
The main submission was a Goshawk-powered biplane that was designated as the Bristol
Type 123.
Along with this, the company also submitted two low-wing monoplane proposals: the Goshawk-powered
Type 127 and the Bristol Mercury-powered Type 128.
Finally, the type 129 was also proposed as an adventurous alternative.
In a way this harkened back to the old pusher fighters of the first world war, except that
it was an all-metal aircraft with a potent four-gun armament mounted in the nose.
Surprisingly, none of these designs were accepted for prototyping, but the company was invited
to build a revised biplane based on the Type 123 proposal as a private venture.
The Bristol design team tidied up the design, streamlined the fixed undercarriage, took
the wing slots and controls from their Bristol Bulldog, and also added drooping ailerons
to serve as flaps.
The updated Type 123 design was submitted to the Air Ministry in March 1933, and the
construction of a prototype was approved shortly thereafter.
With its rather aggressive looks, courtesy of the heavily staggered wings, the 123 looked
promising, but in reality it was a complete disappointment.
It did feature many innovations, including easily removeable fuel tanks, lightweight
but high-strength wing spars, and the lower wing was a new cantilever design that was
produced as a single unit built integral to the fuselage.
But it was too complex, and more importantly too small for its own good, being described
by one observer as the attempt to fit a quart into a pint pot.
Powered by a 695hp Goshawk III engine, it flew for the first time in June of 1934.
Test flights immediately revealed a litany of stability problems; some stemming from
a seemingly undersided rudder, some from ineffective ailerons, and others due to the arrangement
of the wing slats.
Bristol test pilot Cyril Uwins was not impressed by the aircraft at all, and after changes
to the wing slats and rudder dimensions led to no improvement, he declared any further
development would be a waste of the companies money.
Other manufacturers were having similar problems with their own prototypes, either due to the
recalcitrant nature of the Goshawk engine, or due to various other problems.
At this point the Air Ministry realised two mistakes had been made; too much faith had
been placed in the Goshawk engine, and too much preference had been given to the more
conservative biplane designs.
As Bristol had just been awarded a contract to produce the Type 130 Bombay, Frank Barnwell
(the company’s chief designer) felt like the time was right to propose a more radical
alternative for the Ministry’s specification.
He drew up initial plans for a low-wing monoplane of all-metal construction that was to be powered
by a Bristol Mercury radial engine.
Upon reviewing the basic design drawings of the aircraft, dubbed the Bristol Type 133,
the Air Ministry gave permission for Bristol to produce a prototype as a private venture,
which, if reviewed favourably, could be evaluated for a production contract.
Completed in the same year that the Hawker Fury and Handley Page Heyford entered service,
the prototype Bristol 133 made for a striking contrast.
In comparison to the biplanes that dominated British skies, it was sleek and modern, and
it was innovative.
It was the first Bristol aircraft to make used of stressed metal sheeting, rather than
doped fabric covering, and it was the first aircraft designed for the British military
that made use of a retractable landing gear from the start – rather than having it added
onto a design that started with a fixed undercarriage.
The low-mounted cantilever wing of the 133 made it instantly recognisable.
Built as an inverted gull-wing, it gave the 133 a similar profile to that of the Vought
F4U Corsair, which would enter service with the united states about a decade later.
The wing was split into two sections, and it had a constant chord with rounded tips.
The centre section housed the fuel tanks and the undercarriage; the ailerons occupied the
full span of the outer wings and were arranged to droop symmetiricallyy to reduce landing
speed.
Like the retractable landing gear, these were manually operated by a hydraulic hand pump,
meaning the pilot had quite the workout coming into landing.
It isn’t 100% clear whether the prototype was completed with or without its intended
armament, but the design had four .303 calibre machine guns.
Two mounted in the fuselage, synchronised with the propeller, and two were installed
in wing slightly outboard of the undercarriage.
Powered by a 640hp Bristol Mercury VI S.2, the prototype was first flown on the 8th of
June 1934 at Filton Airfield.
Unlike its predecessor, this first flight was very promising, with test pilot Cyril
Uwins claiming that with the right modifications it could be a real winner for the RAF.
Following a few more tests at Filton, the 133 went back to the factory for said modifications.
The wheel brakes were made more effective; the rudder area was increased; the drooping
ailerons were replaced by short-span ailerons and separate split flaps; a sliding canopy
was installed; and a new long-chord cowling was also installed.
In this new guise the prototype took to the skies again in the Autumn of 1934, and after
initial test flights to prove that it was still sound, it went on for an extensive series
of evaluations.
These ran until March of 1935 without incident, and only a few spinning and dive tests remained
before it could go onto Martlesham heath for RAF acceptance.
It was then on the 8th of March that the service, and Bristol, was robbed by fate.
Another test pilot for Bristol, T.W Campbell, took the aircraft up for one last handling
test.
Unfortunately, he forgot that the undercarriage was down when he put the aircraft into a right
hand spin at 14,000 feet, the added drag by the undercarriage caused a premature tip-stall
and the prototype entered into a dangerous flat-spin.
Campbell attempted to correct this, trying to push the nose down and opening up the throttle,
but with the nose of the aircraft chasing its own tail like a caffeine-fuelled terrier,
the centrifugal forces starved the engine of fuel and it died.
Having lost over 8,000 feet of altitude, and with no hope of recovery, Campbell attempted
to bail out.
After a horrifying moment when his foot got caught on the control column he finally got
out with just under 2,000 feet to spare.
The prototype, unaided by a silk parachute, continued on its downward descent into oblivion
and was written off.
Following this incident there were supposedly words exchanged about the decision to build
just the one prototype of the 133, as many companies built two or even three, and the
aircraft’s loss was both a severe disappointment and a severe setback.
With further adjustments, the Bristol 133 could have been a premiere fighter in the
years leading up to the second world war.
It would have certainly been near obsolete by the time hostilities began, but the design
would have probably spawned a successor by that point, one that had taken onboard the
various lessons that were learned with its development.
But as it stood, Bristol had to essentially start over from scratch, so it didn’t bother.
Instead the company moved on to address new specifications issued by the Air Ministry,
and in the future they would do their best to not bet everything on a single airframe.
As always, thank you all so much for watching, and a big thank you of course to the Patreons,
whose details I can now finally update