Balloon Repair Station

Celia, the Swallow and the remarkable Douglas Pobjoy

It is no secret that the Zebedee Crew are avid aviation enthusiasts and have been known to leave the country at the drop of a hat if something interesting turns up halfway round the world. It was no surprise then when a piccie from Celia came through taken in Ireland of an extremely rare aeroplane, none other than a B.A. Swallow II from the 1930s. This particular one had languished unloved, rotting away in a shed for the best part of 30 years near Dublin before it was rediscovered and the long process of restoring it to flying condition started. The story of these remarkable little aeroplanes is quite interesting in its own right but nowhere near as interesting as the little 7 cylinder radial designed by Douglas Pobjoy that powered most of them. See, get me going on something rusty and who knows what’ll happen next.

The twenties and thirties were a high old time for private aviation and many a hopeful aeroplane designer and entrepreneur hoped to make their fortune building light planes for the ever growing number of private flying clubs and aviators. For the vast majority of the new companies their success was short-lived, mainly as a result of the effects of the Great Depression (economically speaking that is) spreading to Britain and finally by the onset of World War II, very few remained, most of them becoming absorbed into the war effort, swallowed up by much larger companies.

The British Aircraft Manufacturing Company and the Swallow along with Pobjoy Air Motors, and most of the companies he supplied, eventually all became victims of the hard economic times. The whole history of the aircraft industry during this period is intertwined and quite complicated. The more you research it the more intertwined it becomes. It ends up a bit like an old boys club, but the one thing that it did do was throw up some of the most skilled and clever designers in the world of engineering. The advances made during these years was huge. You have to remember that it was only a few years after the First World War had really heralded the aeroplane. While the biplane was still being perfected others were developing retractable undercarriage, streamlined fuselages, enclosed cockpits, autogyros and single-spared wings along with aeroplanes you could fold up and keep in a shed.

As it ‘appens, the Swallow is a good case in point. An all wooden British version of the German Klemm L.25 (to be precise) it was a very easy to fly and was a very popular, low-powered, light aeroplane and with the aforementioned wings that could be folded back along the fuselage meaning it didn’t need a hangar to keep it in. As was so often the case the design was so popular that the L.25 ended up being built under licence by the British importer under the guise of The British Klemm Aeroplane Company at London Air Park, Hanworth in Middlesex and became the B.K. Swallow. British Klemm were renamed the British Aircraft Manufacturing Company in 1935, possibly to separate it from its German connections, and hence it became the B.A. Swallow. Another Swallow was re-named around the same time for similar reasons, Swallow Sidecars, becoming Jaguar as the SS motif was deemed rather offensive. I had an SS 1.5 litre saloon for a while before selling to a bloke in America. It was huge and underpowered despite its nice overhead valve engine that ended up in the Triumph Roadster, but I digress. Various engines (not the Jaguar ones) were fitted to the Swallow including the Salmson 9 cylinder radial, inline four cylinder Cirrus Minor and the later more powerful Pobjoy Cataract seven cylinder radial. Cataract being a bit of a reference to Pobjoy’s eyesight I presume. Clearly he had a sense of humour. Over 600 Klemms were produced in Germany and 135 in Hanworth. Production ceased sometime between 1936 and 1938.

The majority of these robust and very safe little planes went to private individuals and flying schools. When the Second World War broke out most were taken by the RAF and issued to the Air Training Corps usually ending up as instructional airframes. A few went to the Royal Air Force Glider Training Squadron based at RAF Ringway near Manchester. The prop was removed and towing hooks fitted to the leading edges of each wing and they were towed singly, in pairs and occasionally threes by Whitley bombers before being released to glide to a target on the airfield to evaluate the future use of heavy gliders in assaults on enemy positions. Around 17 Swallows survived the war and commenced flying once again under private ownership. Less than a handful are known to exist today. EI-AFF is based at the ILAS Field, Taghmon, County Wexford & regularly flies following its lengthy rebuild.

Pretty little aeroplane it may have been, and still is, but the magic of it was the Pobjoy radial which, in its day, was streaks ahead of all the other light aircraft engines available. Douglas Pobjoy suffered from poor eyesight (cataracts!) so was unable to fly, but whilst at Cranwell met up with Nick Comper an enthusiastic aeroplane designer who was looking for a reliable engine for his CLA aircraft. Pobjoy designed his first little radial and bench-tested it at Cranwell and the alliance was born. Comper couldn’t believe his luck. The seven cylinder radial was lighter and more powerful (power to weight ratio) than the majority of small aero engines at the time and so in 1926 Comper chose his first production ‘P’ type engine to power his CLA 4, passing its official Air Ministry Type Test in 1928. See mon braves, paperwork even back then! The success of these engines meant that they went their separate ways. Pobjoy set up Pobjoy Air Motors in Surrey and Comper, The Comper Aircraft Company in Hooton in the Wirral.

Demand for his engines from Comper soon saw Pobjoy Air Motors relocate to Hooton. In 1930 Comper introduced his most popular aeroplane to the private flyer, the Comper Swift fitted with the 2.5 litre Pobjoy R-type engine. This chucked out 85hp but only weighed 135lbs. That equates to under 2lb per horse-power wet. The Swift was a parasol type and was not renowned for its forward visibility whilst on the ground! When the question of forward visibility was raised the stock answer was, “What visibility?” It was though a very popular single-seater which bought flying to the private pilot. The wings folded so it followed the trend of the times. It was a good looking little beast. The heart of any aircraft is its engine. Pobjoy’s skill at fine tuning his engines, which along with their well established reliability, meant that a Pobjoy powered Swift competed in every Kings Cup Air Race from 1931 until 1937. In 1932 the renowned C. A. Butler broke the England to Australia record flying one from Biggin Hill to Darwin in 9 days, another made it to South Africa in a similar time and G-AAZA made a double crossing of the Andes reaching 18,000ft.

By 1933 the recession was hitting the Comper Aircraft Company and following a move to Heston, in a bid to save the company, sadly they ceased trading the same year. Despite this the remarkable Pobjoy-engined Swift carried on breaking records and having adventures. In January 1936 G-ADDT flown by Charles Gardiner made it from Rochester to India and back in two months and, as late as 1981, G-ABTC now named ‘Spirit of Butler’ attempted to replicate his earlier flight to Australia. Following double rotor arm failure it made a forced landing on the old Imperial Airways strip at Jask in Iran. 11 days later she was allowed to return to Dubai but not permitted to carry on to Pakistan so, on one poorly magneto, with the wings and fuselage packed with polystyrene blocks in case a ditching was necessary, it flew out over the sea. It now resides in Cornwall and is being restored, I believe. Richard Shuttleworth, of The Shuttleworth Collection fame, was a director of The Comper Aircraft Company and owned two examples. The Shuttleworth Collection has an airworthy example, G-ACTF.

Whereas Comper had closed, Pobjoy seemed to be surviving the economic downturn, just, and was now providing all the engines for General Aircraft Limited who produced the twin-engined Monospar range of touring and utility aircraft and also getting large orders from Shorts. Taking a huge gamble he moved production, including his, by now, 800 employees to Shorts’ base at Rochester Aerodrome in Kent in 1934. That same year a twin-engined Monospar ST-10 won the Kings Cup powered by the latest 3 litre Pobjoy Niagara radial. Were his eyes now running? Sadly though the Great Depression lingered on and the recovery in Britain was slow. The company started to run into financial difficulties and was finally bought out by Shorts in the same year. Pobjoy, it seems, then joined Shorts and became involved in designing and developing high altitude de-icing equipment.

So popular were his engines that it was reckoned that around forty different types of commercially-built single and twin-engined aircraft used them including a half scale Stirling bomber, a number of prototype long-range ‘fleet watchers’ including the Airspeed Fleet Shadower and autogyros (sorry rotorcraft) including the well-advanced road going Autogiro Company of America’s AC-35. He produced five types of engine in all. The Pobjoy ‘P’ and ‘R’ types along with the Cataract and Niagara where all 7 cylinder air-cooled radials with geared drives, the prop running above the crankshaft plus the Cascade, a direct drive version of the Cataract.

Like so many toppo engineers he was snapped up at the outbreak of the Second World War. For the duration he worked as Chief Engineer at Rotol Airscrews at Gloucester. This was a company formed between (Ro)lls Royce and Bris(tol) Engines and considered the leading edge company when it came to airscrews and which, amongst many firsts, eventually developed the five-bladed props fitted to the later marks of Spitfires. Through Bristol engines he still kept his hand in on the engine development side of things designing an advanced sleeve-valved flat six airborne auxiliary engine destined for the Short Shetland flying boat. Unfortunately, following its maiden flight in 1946, the auxiliary engines’ cooling flaps were incorrectly set and the prototype Shetland I was destroyed in the ensuing fire whilst at its moorings. Perhaps this decided him that there was no future in small lightweight aircraft engines and in a bold backflip he turned his attentions to designing a new tractor, planning to set up a factory in Grantham. Interest was soon forthcoming from the Finnish State Rifle Company who had been directed to cease manufacture of firearms and turn their attention, and the Tourula factory, to producing more peaceful products. This became the State Metal Works (Valtion Metallitehtaat, VMT). In addition to the Rifle Factory, VMT included a former Cannon Factory, an Aircraft Works and its engine plant in Linnavuori in Nokia, and the Pansio Ship Works. Things were looking good for Douglas.

Just when his tractor seemed to be taking off (no pun intended) tragedy struck. In 1948, returning from a sales trip to Helsinki, the SAS DC6 he was travelling on was involved in a mid air collision with an RAF York over Northolt. There were no survivors. The weather had been bad and the DC6 decided to divert to Amsterdam. While climbing it collided with the York which had been cleared to descend. Thirty nine passengers and crew perished in the accident making it the worst British air disaster at the time. The resulting enquiry led to the re-enforcing of the distinction between regional and local pressure settings on altimeters and the raising of vertical separation from five-hundred to a thousand feet within controlled airspace.

Although British aviation had already lost him as leading aero-engine designer his loss to the industry as a whole was widely felt. Douglas Pobjoy was only 53 when he died, had he been around today I’m quite sure we would have had small efficient sleeve valved four strokes powering the aircraft of the new generation of microlight aviators carrying the Pobjoy emblem. The crash happened on the 5th July. I reckon we’ll add that to our official holiday list for next year, but where to go to celebrate this great designers achievements? Ireland or Old Warden?

Big thanks to Flying in Ireland magazine, Gerry Barron and Joe McDermott for their pictures and assistance. great site with lots about Pobjoy and Comper. interesting stuff about this great aviator. great Irish flying magazine with a very helpful staff.