Today we’re looking at the Avro Bison, which was an exceedingly ugly looking biplane that
was built in the early 1920s.
It was built to the same specification that also led to the marginally less offensive
looking Blackburn Blackburn, which was air ministry specification 3/21.
This called for a carrier-capable aircraft that could perform reconnaissance and fleet
gunnery spotting duties.
After receiving submissions from both Avro and Blackburn, the Air Ministry ordered three
prototypes from each company.
Avro was quickest off the mark, and their first prototypes would be complete within
a matter of months of the initial contract being issued.
Although structurally similar to Avro’s other biplane designs, the shape of their
new model 555, being purely functional and dictated by naval requirements, was a little
short of being utterly grotesque.
A large part of this can be attributed to the placement of the pilots cockpit, which
was located high up and in front of the top wing, with the engine cowling sloping away
at a steep angle to provide good visibility for carrier landings.
This gave the aircraft a side profile that resembled something along the lines of a biplane
that had run headlong into a wall, with its nose buckling outward in a comical fashion.
Within this squashed nose was the powerplant dictated by the specification: a 450hp Water-cooled
Napier Lion.
It was installed on a special mounting which also formed a work stand when the engine was
removed for maintenance, something that was later well-regarded during carrier operations
at sea, where ease of maintenance was of paramount importance.
The fuselage was of tubular steel construction, with the central part being clad in plywood
and the rear with fabric, and the nose was protected by aluminium sheeting.
The aircraft was to have a crew of four: a pilot, a navigator, a radio operator, and
a gunner.
The steep, slab-sided fuselage housed a central cabin for the navigator and radio operator,
and it offered enough room for them to be able to stand unimpeded.
Its size allowed for a whole suite of navigation and radio equipment, as well as a complete
plotting table, which was considered quite a luxury for 1921.
However, at some point in the design process it must have been realised that a window was
needed for the observer to..well..observe, and apparently the best thing to use was what
appeared to be a regular window from a bathroom supply shop.
Two of which were installed on each side of this cabin, which gave a remarkable view of
the outside world, whilst at the same time managing to look totally alien in terms of
design and aesthetics when it came to aircraft.
Unlike the navigation crew, the pilot and rear gunner did not enjoy the luxury of an
enclosed cabin.
The pilot’s cockpit was open to the elements, as was the rear gunner’s station, which
was on a raised platform that could be accessed from the central cabin.
The gunner was armed with a single Lewis gun on a scarff ring, and the pilot had use of
a forward firing Vickers machine gun.
The first prototype was completed in the Autumn of 1921.
It had the upper wing mounted directly on top of the fuselage, three arrestor claws
fitted to the axle of the undercarriage, and cutaway wing roots to provide additional downward
visibility.
It was flown at some point in October 1921, though there appears to be no exact date of
when this happened, and problems encountered during its initial flights led directly to
changes on the second and third prototypes that were still under construction.
The biggest issue found had been a lack of longitudinal stability, the cause of which
appeared to be the interruption of airflow over the upper wing caused by the strange
shape of the nose and the placement of the pilot’s cockpit.
As a result of this, the wing shape on the second prototype was reversed and the upper
wing was raised by approximately 15 inches on a series of struts.
This permitted the insertion of a sliding communication hatch between the central cabin
and the cockpit, which allowed the pilot to better communicate with his crewmen without
the need for screaming above the wind.
Some problems with lateral stability had also been noted, and to improve this the rudder
was enlarged and auxiliary fins were mounted under the outer ends of the tailplane.
Side bracing struts were also added to the bottom centre section of the tail, and an
improved metal tail skid was installed to help with landing.
The third prototype was almost identical to the first, but it retained the modified tail
of the second, and this aircraft was used as the template for the first batch of 12
production aircraft which were designated as the Avro Bison mk 1.
Bison 1s did not have the raised upper wing of the second prototype, as this modification
was still being tested when production began.
As a result of this, the first Bisons suffered from poor performance, especially at speeds
below 80 mph.
One of the first Bisons was converted to a floatplane and tested at felixstowe, but its
performance was so abysmal that its sea trails were abandoned after the preliminary test
flights.
The modifications made to the second prototype materialised in the next production batch,
which was designated as the Bison Mk 1A.
Produced under specification 16/23, they featured all the changes of the second prototype, plus
the additional switch from a four-bladed propeller to a two-blade unit.
Later production models had their arrestor gear removed, and the upper wing raised even
further, and these would be designated as the Bison Mk II.
Also, Unlike the Mk 1 model, which had dihedral on both upper and lower wings, the Mk 1a and
Mk II had no dihedral at all.
After passing acceptance trials, which somehow deemed the ugly and vaguely unstable Mk 1
suitable for service, the first Bisons reached operational units in the middle of 1922.
Though originally designed for carrier use, the first operation Bisons were used for coastal
reconnaissance duties, replacing the Westland Walrus biplanes of No.3 Squadron.
The Bison would not actually reach the Fleet Air Arm until No.3 Squadron was disbanded
in April of 1923, after which No.423 Fleet Spotter Flight finally received its consignment
of Bison 2s.
They were initially operated out of Gosport, like No.3 Squadron, but they were later used
in the Mediterranean aboard HMS Eagle.
Other Bisons would find service with the Home Fleet aboard HMS Furious, and units from No.448
Flight also operated from Malta during much of the 1920s.
In service the Bison was not particularly well regarded, and not just because of its
offensive looks.
Even with its modifications it was found to be heavy and cumbersome at slow speeds, and
its sluggish top speed of 110 mph meant that it often struggled with strong headwinds.
This made it less than ideal as a reconnaissance aircraft, and not particularly useful as a
gunnery spotting unit either…as it flew at such a slow pace that it would be a sitting
duck for naval fighters or enemy anti-aircraft batteries.
Despite their drawbacks, the Bisons enjoyed a fairly long service life, operating throughout
the 1920s before finally being retired at the end of the decade.
Though they were woefully slow, they did technically perform the requirements to which they had
been built.
They were replaced by the Fairey IIIF, the latest iteration of an aircraft design that
actually predated the Bison itself by almost four years.
The Fairey was also considerably easier on the eyes, which would have made a nice change
for the crews of the Fleet Air Arm.
A similar fate awaited the Bisons equally ugly competitor, the Blackburn Blackburn,
but I’ll spare the ugliness of that aircraft for another day.
As always thank you so much for watching, and a big thank you to the patreons.
With a special shoutout to Kevin, Delliardo, Bane, FB, Christopher R, Tronathon, Erik Hindman,
John Austin Jr, Ray Culotta, Keith Tarrier, Greenseaships, Northlincsweb, and MCT for
their support as Wing Commander Tier Patreons.