The Saunders-Roe SR.45 Princess.
An excellent example of how Britain’s aviation industry had misread the changing trends in air travel.
Essentially, the Princess had no reason to exist at all, as by the time this gigantic
flying boat took to the air in 1952, the technology and requirement for such a behemoth was so
outdated it was practically an ancient artefact.
Prior to World War II, the flying boat was a formidable part of international air travel.
As commercial aviation was still in its infancy, many land-based airports had not been constructed
for aircraft larger than the Douglas DC-3 or the Boeing 247.
Therefore, the only option was to utilise existing ports and harbours through the use
of gigantic flying boats, which, for all intents and purposes, were wings and engines attached
to ship hulls.
The concept was a widely adopted strategy, with Pan Am pioneering transpacific operations
with their famous Clipper service between San Francisco and Tokyo via Hawaii.
In Britain, Imperial Airways served the British Empire through the use of flying boats such
as the Short Empire and the S.26, which were larger than contemporary land-based airliners
and therefore could accommodate greater capacity and luxury.
The flying boats of this era were the cream of air travel, emulating the classical first-class
experience of the ocean liners but at double the speed.
Following the start of World War II, Imperial Airways lost its flying boat network as hostilities
prevented the continuation of civilian services.
Although commercial services did continue between London and New York using Boeing 314
Clipper flying boats, flights to the Empire’s vast colonies were effectively cut off.
Meanwhile, numerous land-based airfields were constructed as fighter and bomber bases in
order to defend Britain from the Luftwaffe, as well as launch strategic aerial strikes
against Germany itself.
As such, by the end of the war in 1945, many of the dozens of
ex-RAF bases were converted into civilian airfields.
During the war, Imperial Airways had been merged with the original British Airways by
the government to create the British Overseas Airways Corporation (BOAC) in 1940.
Much like the Brabazon Committee, the British government considered long before the end
of hostilities reviving their shattered flying boat network, although the concept of building
a flying boat was not mooted as part of the Brabazon Committee.
Instead, the Air Ministry approached the two main pre-war flying boat manufacturers, Saunders-Roe
(Saro) and Shorts, to discuss a collaboration between the builders.
What resulted was the
Short Shetland, an enormous recon flying boat that was to replace the Short Sunderland as
the RAF and Royal Navy’s military flying boat.
However, after only two units were produced, the war ended and the aircraft was surplus
to requirement.
Nevertheless, much of the technology behind the massive Shetland would be taken forward
in a civilian capacity.
During 1943, as plans for the Shetland were drawn up by Saunders-Roe and Short, specifications
for a commercial flying boat were also laid out, which proposed the largest all-metal
flying boat ever built with a weight of 140 tons, a pressurised 'double-bubble' hull,
a 214-foot wingspan, a height of 55 feet 9 inches, and a length of 148 feet.
The proposed aircraft would be capable of a cruising speed of 340mph and could fly at
37,000 feet over a range anywhere between 3,600 and 5,100 miles, while also capable
of carrying in sublime accommodation around 104 passengers.
When the Ministry of Supply, in 1945, reissued their request to develop a long-range flying
boat to restart transatlantic services, Saunders-Roe stepped immediately up to the challenge with
their wartime design.
Perhaps the most endearing feature of the aircraft was the fact that it would be the
first flying boat powered by turboprops, employing the Bristol Proteus as its main source of power.
In May 1946, Saunders-Roe’s bid won the Ministry of Supply’s contract and construction
was allowed to commence on three SR.45 flying boats.
While much of the aircraft’s development had been done during the latter years of World
War II, as well as having many design features based on the previous Shetland, the SR.45
project immediately ran into schedule and cost overruns, leading to a debate in the
House of Commons as to the viability of flying boats in general.
One major bugbear of the scheme was the airframe design and the use of the Proteus engines,
which were so cutting edge that Saunders-Roe had completely underestimated how long it
would take to develop them.
In 1951, the rug was essentially pulled out from beneath the project after BOAC re-evaluated
its position and concluded that there was no commercially viable future for flying boats.
Airports, such as London Heathrow and New York Idlewild, meant that land-based airliner
designs could be developed to larger sizes than ever before, rendering the need for water-based
flying boats moot.
In 1950, the last BOAC flying boat operations were undertaken, and the SR.45 Princess was
left completely without a market to serve.
Regardless, work continued, with the intention instead being to use the massive aircraft
as an RAF recon flying boat.
However, in March 1952, Saunders-Roe announced that once the first prototype had been completed,
the second and third would be put on hold to await more powerful engines.
Finally, on August 22nd, 1952, the first prototype, G-ALUN, undertook its maiden flight, which
lasted 35 minutes and circumnavigated its Isle of Wight home.
The truth was that this maiden flight was actually unintentional, as the aircraft had
only been booked to undertake taxiing examinations.
However, the test pilot, Geoffrey Tyson, took it upon himself to force the plane skyward
due to the perfect weather conditions.
Test flights continued throughout the remainder of August, and in September it was scheduled
to appear at the 1952 Farnborough Airshow.
Sadly, the SR.45 wouldn’t make it to Farnborough, as reliability problems with the Proteus engines
meant it was forced to withdraw.
Further testing revealed that problems with the engines could be traced to the build quality
of the gearbox, but such issues didn’t prove fatal to the aircraft’s ability to fly.
Eventually, the SR.45 did show up at the 1953 Farnborough Airshow, and testing of the aircraft
would continue until May 27th, 1954, by which time tuning and evolution of the Proteus engine
had delivered the flight performance originally desired by Saunders-Roe.
G-ALUN was the only example to fly, in which it undertook 46 test flights and clocked up
100 hours flying time.
Regardless of the first prototype’s success, one couldn’t ignore the fact that the SR.45
was a flying antique.
With technology dating back to the 1930s, and with the general trend aiming towards
turboprop and jet aviation, the government decided that the project would be suspended
pending further investigation.
The two unfinished prototypes, G-ALUO and G-ALUP, as well as the operational G-ALUN,
were placed into warm storage around the Isle of Wight, one at the Saunders-Roe factory
in Cowes, while the other two were tied up at Calshot Spit.
Although the general consensus was that the flying boat had no future, hope still existed
that the SR.45 would be taken up by a potential buyer.
While several offers did come and go, including a proposal to fit the aircraft with Rolls-Royce
Tyne engines from the Breguet Atlantic, none ever came to fruition.
In the end, after languishing for ten years, the three SR.45s were purchased by Eoin Mekie
on behalf of Aero Spacelines during the bankruptcy auction of Saunders-Roe, which collapsed in 1964.
The intention was to use the three gigantic SR.45s as freight transport aircraft as part
of the Saturn V rocket project for NASA, delivering components to the Cape Canaveral launch site.
However, by the time they were taken out of storage and re-examined, it was determined
that the stored trio had corroded beyond economic repair, and all were promptly scrapped in
1967, bringing a sad and sorry end to the legacy of Britain’s flying boats.