The Saunders-Roe Princess

Published on August 22, 2012

In the early 1950s, the Saunders-Roe S.R.45 Princess was the largest flying boat ever built in Britain and, indeed, one of the largest aircraft ever conceived in history.  It could carry 105 passengers in style and the comfort of spacious sleeper cabins on two decks within a pressurized hull.  Fine seats, stand-up bars, a lounge and spacious bathrooms were part of the deck plans.  All of the comforts of “modern air travel” were envisioned, making the plane the crown jewel of airline travel.  Further, the Princess would have linked Britain with the Far East since the aircraft boasted a non-stop range of over 5,000 miles.  Amazingly, it could have cruised at 39,000 feet of altitude.  Yet the Princess was doomed from the start, finding no buyers despite its extraordinary capabilities.  Caught at the crux of change, it was the pinnacle of flying boat designs launched into the dawn of the new, land-based jet age.


The Bristol turboprop engines with counter-rotating propellers on the wing of the S.R.45 Princess.


A Technical Triumph

The Saunders-Roe S.R.45 Princess was an engineering marvel.  Not only was the design huge, nearly rivaling the scale of the rather less capable Spruce Goose, but it also featured new generation turboprop power plants.  The Princess was fitted with ten Bristol Proteus turboprop engines, eight of which were coupled in tandem to drive counter-rotating propellers, while the remaining two outboard engines each drove a single prop.  The Proteus engines produced over 3,000 hp each and thus, the aircraft would have produced a combined 30,000 hp.


The interior layout of the S.R.45 Princess as depicted in the company’s promotional literature — advertised as a “Richard Lonsdale-Hands design” — click to review the details of the layout.

Based on design specifications offered by Saunders-Roe Ltd., the British Government requested that three of the giant seaplanes be built specifically to serve BOAC’s trans-Atlantic route between London and New York.  The three Princesses were together constructed in the largest hangar in the Saunders-Roe company, located at Cowes on the Isle of Wight.  Even then, the planes were so huge that they had to be winched down to ensure that the 54 foot high tail cleared the hangar doors.  Only when the prototype Princess was outside of the hangar could the engines be fitted.  Thereafter, the plane was issued the tail number G-ALUN and readied for its first test flights.

First Flight — 60 Years Ago Today

On August 22, 1952 (sixty years ago today!), the Saunders-Roe S.R.45 Princess prototype G-ALUN was taken out by the company test pilot, Geoffrey Tyson.  Once motoring around on the light waves off the Solent, Tyson reported that the conditions were perfect for a test flight — and likewise, the Saunders-Roe management thought it would be a public relations coup to fly the plane earlier than planned.  A more extensive set of taxi-trials were skipped over and the plane made its first flight, lifting off the waves and orbiting the Solent.  It reached 225 mph while the cameras rolled and the first flight covered 120 miles of distance flown, ending in a perfect touchdown back on the Solent.


The Saunders-Roe SR.45 Princess in flight.

After landing, Geoffrey Tyson described the Princess as handling like a fighter plane, not like a huge airliner at all — a perfect public relations coup.  The plane was stable, light on the controls and had an abundance of power.  After its first flight, the prototype returned to the carefully outlined test program and was soon issued a type certificate.  In short order, Saunders-Roe was advertising the giant flying boat to as many airlines as it could, reaching even as far as Australia’s QANTAS with offers for it to be an early launch customer.  Meanwhile, with faltering support from BOAC, the other two aircraft in construction at the Cowe hangar were held back.  In 1953, the Princess was brought to the Farnborough Airshow in an attempt to drum up business.  It even made a surprise flyover to the amazement of the crowds.

The End of the Line

Despite the best efforts of the marketing team, the projected high operating costs of the Princess drove off the few buyers who might have been enticed to consider the giant flying boat for their line operations.  Put simply, ten engines and a huge hull that had to be constantly maintained against salt water corrosion carried a huge cost.  Furthermore, by the early 1950s, commercial airlines were abandoning seaplane operations.  They opted to acquire land-based jets as being more cost-effective.  Ultimately, even the giant aircraft’s original buyer, BOAC, abandoned the project entirely.  BOAC and the Government of Britain made an ill-fated decision to proceed not with the Princess but with the de Havilland Comet.  That fateful decision would not only spell the end of Saunders-Roe as a fixed wing commercial airline manufacturer but also result in the disaster of the Comet.


The S.R.45 Princess in all of its glory, on the day of its first flight, 60 years ago today in aviation history.

Certainly the Saunders-Roe SR.45 Princess would have set a new standard for luxury air travel.  Certainly it would have driven airlines in a different direction, for at least a while longer away from land-based airports toward seaplane bases around the world.  Yet also certainly the Princess would have been a maintenance and fuel hungry nightmare.  It would have been non-competitive from the start.  With the failure of the Saunders-Roe Princess, the era of the seaplane and flying boat had come to an end.  Today, as we sit cramped in the “cattle car” section of the modern airliners that ply the routes between Europe and the United States and Asia, we can look back with wonder at the luxury that would have been within reach aboard the Saunders-Roe Princess.

Above all, it was a grand plane, the penultimate flying boat airliner of history.


One More Bit of Aviation History

The de Havilland Comet 1, the world’s first commercially produced jet airliner, entered in the early 1950s.  From the start, design flaws resulted in a number of crashes in the first few years of the airliner’s service career.  Many lives would be lost due — at first due to unknown causes.  A government commission of inquiry was convened to uncover and fix the plane’s flaws and after extensive research, the findings of the commission pointed to a number of key issues to address.  The one flaw that everyone points to as the most compelling was a simple one.  The de Havilland designers had eschewed the common round or oval passenger windows in favor of more visually interesting square frames.  The square corners of these windows were stress points that soon suffered from the effects of metal fatigue.  This seemingly minor issue resulted in catastrophic inflight structural failures with the loss of all lives — the plane literally came apart in midair.  In later iterations of the Comet’s design, the plane’s flaws were resolved and it would go on to fly for decades in successful commercial and military service.


6 thoughts on “The Saunders-Roe Princess

  1. John Voss says:

    Your daily aviation history files are most interesting and I look forward to them each day. I might make one suggestion, that the text on each of the Daily Stories could be a bit darker so as to make it easier to read. It is too grey in my opinion.

    John Voss

  2. t.j.smith says:

    Is there a museum in Southampton? I was told there was.

  3. says:

    GAR’s Karl Drage got airborne to capture some of the commemorations from above. The story of the Saunders-Roe Princess – the largest all metal flying boat ever flown – began in 1945 when the British Ministry of Supply invited the company to bid for the right to design and build a civil flying boat that was capable of flying non-stop across the Atlantic, on behalf of British Overseas Airways Corportation (BOAC).

  4. Neville Robinson says:

    Hi. My father worked for Saunders Roe from the end of the war and taught the executives to drive. His name was Wilfred Ernest Robinson, he ran a guest house on the island at Freshwater. He actually took me around the Princess Flying Boat when I was about three. I am now seventy one. A real memory. Thanks

    Neville Robinson

  5. Adrian Wagstaff says:

    Nicely written. All these stories of the giant flying boats and the Ekranoplan in Russia inspired me to write a novel. It’s called the Pelican Affair and is available on Amazon. Apologies for self-promotion, I’m rubbish at it, but I thought you might like my book.


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