Saturday 18 March 2017

R. J . Mitchell's Air Yachts

R. J. Mitchell was responsible for two luxury air yachts although both, in fact, began as military orders. The first looked backwards to the Southampton but the second might very well have led to a Supermarine equivalent of the Catalina.

The first came about as a request from Denmark for a torpedo-carrying version of the Southampton; it was to be called "Nanok", Inuit for polar bear, and first flew in 1927.  But all was not well as the necessary positioning of the torpedoes, one on each side of the aircraft, produced problems when  dropping only one torpedo and the three-engined layout that had been requested by Denmark was also found to produce trim problems. Mitchell's response was to fit an auxiliary elevator higher up between the three fins but this lowered the flying speed some mph below that contracted for.  And so, in the end, the Royal Danish Navy took delivery of a standard Southampton instead.

Luckily, in 1928, the Hon. A. E. Guinness was persuaded of the potential of a private flying-boat and thus the unwanted Nanok was converted into an ‘air yacht’ with comfortable cabins to carry up to twelve passengers. Now finally named ‘Solent’ and registered G-AAAB, it soon became a familiar sight, flying from the Hythe seaplane base on Southampton Water to Dún Laoghaire harbour, County Dublin, and thence to Lough Corrib, County Galway, close to Ashford Castle, its owner's home.

The second Air Yacht was to follow in 1930, again a cancelled military prototype, which began as Air Ministry specification 4/27, calling for an armed reconnaissance flying-boat. Instead of the expected wooden-hulled biplane, there appeared an uncompromising all-metal monoplane with a wing-span of 92 feet and powered by three engines which were faired into the wings. It had a plank-shaped parasol wing with sloping V struts supporting the wing about two thirds out from the centre-line and the hull, instead of the curvaceous design made famous with the Southampton, was a flat-sided type and strengthened with horizontal corrugations; it also had extremely angular fins in keeping with the rest of the general arrangement.
Supermarine Air Yacht (from a painting by author)
The new design still had fabric covered flying surfaces but it had one feature which made it stand out from all other Supermarine aircraft and its contemporaries and this was the employment of sponsons attached to the lower sides of the hull instead of the customary wing-tip floats. Not only in this respect but also in respect of the overall design, the aircraft bore an uncanny resemblance to the earlier Dornier Wal seaplanes: indeed a Supermarine employee, Harrry Griffith, later wrote the Mitchell "had allowed himself to be lured by some of his bright boys into following other people's ideas".
    Unfortunately, the aircraft did not give a dramatic argument for going over to monoplanes as its maximum speed was well below expectations. And so it was  re-engined with 525 hp Armstrong-Siddeley Panthers and was then found to be capable of 117 mph; however, it was still not possible to maintain height with any significant payload when one of the three engines was throttled back. Also, Penrose  recorded that ‘unfortunately the sponsons suffered battering by waves and even on calm water gave inferior take-off compared with the usual chined British hull' although he did go on to say that ‘assessed as an engineering structure of considerable aerodynamic cleanness, the Air Yacht was a big step forward compared with the established three-engined Iris biplane, of which four were in the course of delivering to the RAF, or the Calcutta-derived Short Rangoon prototype due to fly in the summer.’ Griffiths, also gave a negative report: ‘It had a very long take-off run and there was always doubt as to whether it would leave the water at all with a full load of passengers, stores and fuel. Refuelling in those days was done with hand pumps from barrels taken out on a barge. There is a story (unconfirmed but, knowing the man, possibly true) that Biard, the test pilot, refused to attempt a full load take-off and ‘went through the motions’ of filling with fuel by pumping from a number of barrels, some of which were empty'.

And so, by 1931, Supermarine began to try to salvage matters by seeking civil registration,  in the expectation of fulfilling an order from the Hon. A. E. Guinness for a replacement for his ‘Solent’ Air Yacht. The new machine’s boxy hull certainly provided very suitable dimensions for the passenger cabin: 35 feet in length, 6 feet 6 inches in height and 8 feet in width. It was luxuriously appointed with owner’s cabin complete with bed, bath and toilet, a galley with full cooking facilities beneath the wing, and additional wash basins, toilet and comfortable lounge with settees and sideboards in a separate cabin for five other passengers; and the temperature could even be regulated by a blown air system.

Unfortunately Guinness turned to a Saro product and the Air Yacht was put in storage. But eventually a Mrs. June Jewell James, a keen motor-boat and flying enthusiast. saw the aircraft and negotiated its purchase from Supermarine in 1932. She named her new acquisition ‘Windward III’ and became so impatient to have the use of her new purchase for a cruise to the Mediterranean and North Africa that she insisted on starting some days before the prearranged departure date.
     Biard has supplied a description of the frantic preparations and of one-and-only cruise attempted in the aircraft. After Mrs. James and her companions were nearly drowned in a fierce storm, when anchored in Cherbourg Harbour, Biard flew the Air Yacht down to Naples whence Mrs. James proceeded to obtain audiences with both the Pope and Mussolini. Biard had then to hand over the Air Yacht to a relief pilot as his stomach muscles, which had been torn in the S.4 crash of 1925, needed surgery. Unfortunately, the Air Yacht suffered an engine failure and stalled into the sea on take-off in the vicinity of Capri on January 25. The owner suffered a broken leg but otherwise there were no serious injuries sustained; the aircraft was too badly damaged to be worth salvaging.

Had Mitchell lived long enough and had the Air Ministry generally shown a more single-minded faith in monoplane flying boats, one wonders if Mitchell’s last flying-boat, the Stranraer biplane, would instead have been a Supermarine Air Yacht type equivalent to the American Catalina which equipped twenty-one RAF and RCAF squadrons during World War II. Incidentally, the predecessor of the Catalina was the Consolidated Commodore, with a parasol fabric covered wing like the Air Yacht and with about the same span; it appeared in the same year as Mitchell’s machine but was far less clean, aerodynamically, with well over thirty supporting struts.

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For reference sources, see my Blog: “Source Material and References. " An extended bibliography is included in my R.J.Mitchell at Supermarine; Schneider Trophy to Spitfire  which also provides material for wider reading, grouped according to specific areas of interest. 

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