In the mid 1930s the RAF was in need of a newer, more advanced single-seat fighter to
replace their ageing fleet of biplanes.
In response to this need, the air ministry issued specification F5/34.
Several manufacturers submitted designs some would make it, some didn’t, and they will
all be covered in their own videos, but today we’re looking at the submission by Gloster.
This new specification, which would ultimately lead to the Hawker Hurricane and Supermarine
Spitfire, was a considerable step up in design requirements in comparison to previous specifications.
The new fighter had to come with a fully retractable undercarriage, it had to possess a top speed
of 275mph or 442 km/h at 15,000 feet, it had to have a fully enclosed cockpit with an oxygen
supply, and it had to come with six or eight 303 browning machine guns with 300 rounds
of ammunition each.
These high-performance requirements would prove a challenging – but not impossible
– obstacle to overcome…at least for designers who were not doggedly stuck in the past, and
when approached with the Air Ministry’s specification, Gloster was quietly confident
owing to the successes of the Gloster Gladiator.
Known unofficially as the Gloster ‘Unnamed Fighter’, the F.5/34 would be the last aircraft
designed for the company by HP Folland, who left after Hawker’s acquisition of the company
in 1937.
Interestingly, the Air Ministry specification did not dictate a particular type of powerplant
that was to be used, something which had hurt several promising designs in the past, and
so Folland decided to go with an air-cooled radial engine on the grounds of reliability.
Folland collaborated with H.E Preston on the design of this new fighter.
Initially, the aircraft had a more primitive design compared to what would eventually be
built.
Leaning heavily on the design principals of the Gloster Gladiator, its fuselage would
have been glad in fabric, and it would have only featured a partially enclosed cockpit,
which had a detachable overhead fairing with open sides.
The powerplant originally selected was the relatively new 9-cylinder Bristol Perseus
sleeve valve radial engine, but by 1936 several major design changes had been made to improve
Gloster’s competitiveness, and this also included a change of engine.
In the re-design, Folland went with a geared, supercharged Bristol Mercury IX that produced
840hp.
This was done due to concerns about the reliability of the still somewhat experimental Perseus
engine, and as the Bristol Mercury had seen stunning success with the Gloster Gladiator,
Folland chose to play it safe.
The Mercury was enclosed in a new long-chord cowling with a leading-edge exhaust collector
ring, and to improve cooling over the original design it also had controllable cowl flaps.
The fuselage was a monocoque structure that was built up from oval section rings, the
fabric coverings were done away with in the re-design and the Gloster was now to be clad
in a stressed duraluminium skin.
The wing was built in one piece, with the light-alloy spars running from tip to tip,
and the ribs were made from steel and light alloy tubing.
Like the fuselage, the wings and tailplane were also covered in a stressed metal skin,
and the ailerons, rudder and elevators were clad in fabric.
The aircraft also featured split trailing-edge flaps, however these were built with an all-metal
construction and like most emerging designs at the time they were hydraulically powered.
Another noticeable change in the redesign was the canopy, which now closely resembled
that of the Gloster Gladiator, being fully enclosed and retractable.
It also offered superior all-round visibility compared to the previous design as the original
had its canopy faired into the fuselage.
Though it looked like a conventional design, in the ways that we now perceive early monoplane
fighters, the F5/34 did feature a couple of oddities.
Firstly, there was the design of the landing gear, though it was retractable, it was not
fully retractable.
The mainwheel retracted rearwards into the wing, but a large section of it was left exposed.
This was done so that in the event of a wheels up landing the main point of impact would
be the wheels rather that the underside of the airframe.
Though this sounded like a potentially cost-saving strategy, and indeed a few other manufaturers
tried this technique, it would ultimately prove to be a brief and rarely used design
feature as the benefits of only somewhat reducing the damage of a potential wheels up landing
were vastly outweighed by the increased drag produced during every flight irrespective
of the chances for said wheels-up landing even occurring.
The second design oddity was the tail.
In the redesign a new tail unit was adopted, in which the tailfin and rudder were set further
forward than the tailplane and elevator.
This was done to aid in spin recovery, a topic that was rapidly evolving with the change
from biplane to monoplane designs, and it was hoped that spin recovery would be improved
by moving the rudder ahead of any disturbed air caused by the tailplane.
Again, this would be a design feature on a few other aircraft as well, but for one reason
or another it never took off – pun fully intended.
The updated design submitted by Gloster resulted in the production of two prototypes.
The first was built as an unarmed model, and it was flown for the first time in December
of 1937.
The second, completed with a full complement of eight machine guns, was flown for the first
time in March 1938.
Like the other competing prototypes, the aircraft’s armament was mounted in the wing, outboard
of the propeller disk.
This eliminated the requirement for a heavy and complex synchronisation gear, and it took
full advantage of the growing reliability of remotely operated machine guns.
During its initial trials the Gloster prototype performed well, in fact it managed an almost
identical top speed compared to the Hawker Hurricane despite having approximately 100hp
less than its competitor.
But overall, the Gloster prototype was doomed, and this was for two main reasons.
Reason one.
The Gloster may have performed well compared to the Hurricane, but its Bristol Mercury
engine was reaching the end of its development potential, whereas the Merlin engine was only
at the beginning of its own.
This meant that when a replacement for the Mercury engine would eventually be needed,
Gloster would be limited in their engine choices, as anything with dimensions or cooling requirements
dissimilar to the Mercury would more than likely require a major redesign.
The other reason for Gloster’s failure was, ironically, their earlier successes.
Much of their development and production capacity was taken up with existing orders for Gloster
Gladiators and Gauntlets, and this meant that they had limited resources to spare on a new
project.
And so, despite being structurally more advanced than the Hurricane, the Gloster prototypes
were so slow in development that they only began performance trials when the Hurricane
itself was already entering service.
There was definitely room for improvement to bring the Gloster up to a more modern specification.
Its airframe could easily bear the fitting of a more powerful engine, albeit with some
redesign work on the nose, and the wing-mounted machine guns could have easily been swapped
out for cannons later on.
But the air ministry saw zero reason for wasting money on either of these endeavours when the
Spitfire and Hurricane were already fulfilling their roles to admiration.
And so only two examples of Gloster’s unnamed fighter would be built.
After completing their flight trials, they were transferred to the Air Ministry for use
at RAE Farnborough and various other establishments.
This they did until around May of 1941 when they were then transferred for use as ground
instructional airframes…and at some point later they were both scrapped.
Though the project was not a success for Gloster, their takeover by Hawker in 1937 would breath
new life and new ideas into the company.
However this turn of events did not please Folland, who felt that the new owners would
favour the designs of Hawker’s own Sidney Camm over his.
When Folland resigned to form his own company he was replaced by W.G Carter, who would go
on to design the company’s most well-rememberd aircraft: the gloster meteor.
But that’s a story for another day.
As always thank you all very much for watching, and a special thank you of course to the Patreons,
with a special shoutout to Kevin, Delliardo, Bane, FB, Christopher R, Tronathon, and Erik
Hindman, for their support as wing commander tier patrons.
Thank you all so much, and I’ll catch you all next time.