Napier Lion: King of Engines - Part 3
Wednesday, 18 April 2012 | Admin
By BobHad the Napier Lion engine only powered the record breaking cars and boats covered in the earlier articles of this blog, it would have been enough to place the Napier Lion in any ‘engine hall of fame’. In fact the Lion was primarily designed to power aircraft and in a lengthy period of service did so in at least 30 types of production aircraft and 11 different racing planes that the writer is aware of. A discourse on the Lion engine and Lion powered aircraft would easily fill a substantial book, so this article will limit itself to the racing models, and specifically the Lion powered Gloster and Supermarine aircraft designed to contest the Schneider Trophy.
Schneider commissioned the sculptor Ernest Gabard, a fellow flight enthusiast, to design and create the trophy. Gabard came up with a silver plated sculpture mounted on a substantial marble base representing the Spirit of Flight kissing a sea wave in which the heads of Neptune and three Tritons were depicted. The Schneider Trophy would be contested for the first time in the following year - 1913.
Supermarine Sea Lion II
The Great War put an end to Schneider Trophy racing in the years 1915 to 1918. The British, having won the last 1914 event in Monaco, chose to host the 1919 Schneider Trophy race at Bournemouth. Supermarine Aviation took the recently launched Napier Lion engine and fitted it into a modified Baby seaplane to produce the first series of their Sea Lion range. The weather was foggy during the preliminary Schneider trials and the Sea Lion II, piloted by Basil Hobbs, struck some flotsam during the first compulsory landing trial, damaging and sinking the aircraft. Due to continuing dangerous fog during, the Schneider contest was annulled by the referee that year.
The 1922 event was challenged by three nations – Italy, France and the single Sea Lion II private entry from Great Britain. Funded by Hubert Scott-Payne (see previous article on Lion powered speedboats) the Sea Lion II was piloted by Henry (Henri) Charles Biard, Supermarine’s chief test pilot. Perhaps recognizing the stiff competition from the Italians and the British, the French withdrew from the race. The Italians, in the much fancied Macchi M17’s and a Savoia S.51 took an early lead. Tactically, flying three abreast to make overtaking difficult, they kept this lead for six laps of the course. Proving the worth of the Supermarine design and the power of its Lion engine, Biard flew over the top of the Italian formation to take and hold the lead to the flag. By winning the 1922 event, Biard and the British prevented the Italians from achieving a consecutive triple and gaining the trophy outright.
The Nighthawk had a good airframe for the time, but suffered from an unreliable engine. Gloster took the decision to develop the Nighthawk into a racing aircraft using the Napier Lion II as the power-plant. The developed plane, named Mars I, was launched in 1921 and attained a British air speed record of 196.4 mph. Mars I went on to make an attempt on the world air speed record held by a French Nieuport-Delage but did not exceed the existing record sufficiently to be recognized by the governing body, the Fédération Aéronautique Internationale. Mars I was further developed into the Gloster I which was fitted with floats and served as a training aircraft for Schneider Trophy pilots.
Through the 1920’s Gloster produced four more seaplanes designed to challenge for the Schneider Trophy – the Glosters II, III, IV and VI. The Gloster V design was abandoned due to centre of gravity problems and the biplane layout effectively becoming obsolete. Of this series of racing planes, the Gloster III and Gloster VI are regarded as the more successful, though neither won the Schneider Trophy for which they were designed.
Having won the previous 1923 Schneider Trophy race the United States hosted the next 1925 event at Baltimore. Three countries were challenging for the trophy, United States, Italy and Great Britain. The US team was composed of two navy and one army Curtiss R3C.2 aircraft, the Italians brought two Macchi M33’s, and the British entered two Gloster IIIA’s and a sole Supermarine S.4 - both the Gloster and Supermarine planes having Napier Lion engines.
Once again, the Supermarine would be piloted by Captain Biard. Captain Hubert Broad and the Australian Bert Hinkler would be at the controls of the two Gloster IIIA’s. Following a crash of the Supermaine S4 early in the competition, the Gloster piloted by Hinkler, snapped a bracing wire preventing Hinkler from completing the prerequisite navigability and mooring tests in the allocated time. Sportingly, the US and Italian teams petitioned the referee who allowed Hinkler to complete the tests a few days later when the conditions were more suitable. On Monday 26 October, though the conditions were much better, the sea was rough when Hinkler came to land for the taxi test. Though landing successfully, the float struts collapsed and the fuselage dropped onto the water. The propeller, which was still rotating, damaged the floats and the machine was towed to the docking shed and withdrawn from the competition.
In the competition James Doolittle set a Schneider record speed of 232.57 mph. Captain Broad, in the other Gloster IIIA, seemingly took his turns cautiously wide and could only manage 199.21 mph. Nevertheless, this was good enough to give the British second place ahead of one the remaining Macchi M33’s and the other two Curtiss aircraft.
Here’s a clip of Broad, the Gloster IIIA and preparation for the 1922 Schneider Trophy –
Supermarine S.4 and S.5
By 1925 the trend towards racing monoplanes had begun. For that year’s Schneider Trophy race both Macchi and Supermarine produced monoplane designs. The Supermarine S.4 had the cleaner and more elegant lines with the Napier Lion VII engine neatly cowled into the fuselage. The unbraced wing was set at mid-fuselage height and the plane sat on twin floats. Lamblin radiators under the wings and centre section of the fuselage took care of the necessary engine cooling. With sleek lines and no bracing, the S.4 seemed the epitome of a modern racing seaplane. By contrast, the Macchi M33kept to a flying boat design. Surprisingly, Italy had no competitive aero engine at the time and the M33 was fitted with an American Curtiss D12 motor set on struts above the fuselage, slightly forward of the cockpit and wing.
Before the Schneider contest in October, the Supermarine S.4 was taken to Southampton Water where it set a new British and World seaplane record of 226.752 mph.
With the latest Supermarine racer destroyed and the Glosters no longer competitive against the American Curtiss and Italian Macchi aircraft, the British did not contest the 1926 race, leaving an Italian Macchi M39 to pick up that year’s trophy. Realistically, the British manufacturers set their sights on the 1927 race. The rules of the Schneider now required national teams to be represented by teams from their armed forces. The Air Ministry set about establishing a ‘High Speed Flight’ containing pilots of the caliber necessary to fly racing aircraft. To cover a variety of design and performance options, the Ministry commissioned Gloster, Shorts and Supermarine to build their respective racing seaplanes. Gloster produced two Lion powered Gloster IV biplanes and Shorts submitted a single Crusader monoplane designed by Roy Feddon and powered by a Bristol Mercury radial. Having no existing competitive seaplane, Mitchell and Supermarine set about designing a new aircraft, the S.5.
Unlike the recent S.4 whose airframe was constructed largely of wood, with some metal included only in the fuselage section, the Supermarine S.5 featured a duralumin semi-monocoque fuselage and tight engine cowl. Much slimmer than the S.4, the S.5 reduced its drag even further by making the rivet heads flush with the surface panels. Of necessity, the low set wings of the S.5 went back to being braced to improve stiffness and avoid the dangerous flutter of its predecessor. Instead of the Lamblin radiators of the S.4, more streamlined wing surface radiators made up of copper tubing were installed in the S.5. To counteract propeller torque on take-off the starboard float was offset outwards by 8 inches compared to the port float, and a further initial weight offset was achieved by using the starboard float to carry some of the fuel. Though eyeing the recent Rolls Royce engines, Mitchell stuck with the Napier Lion power-plant, though this would be the last time the Lion would be used in a Supermarine racer.
In all, three S.5’s were built for the 1927 race, one powered by the 900 bhp Lion VIIA engine and two with the VIIB 875 bhp motor. The VIIA powered S.5 had direct drive to the propeller whilst the VIIB planes, although slightly down on maximum power, were geared down for a higher torque drive to the propeller.
Having won the 1926 event, Italy was hosting the 1927 race at Venice. Italy, Britain, and the USA would contest the Schneider Trophy that year. The American entry, a Mercury Racer piloted by Al Williams sank during the tests at the preliminary stage. The home team of three Italian Macchi M52’s were piloted by Bernardi, Guazetti and Ferrarin. The British team consisted of Flight Lieutenants Worsley and Webster piloting the two S.5’s, N219 and N220 respectively, and Flight Lieutenant Kinkead in a Gloster IVB. The Shorts Crusader proved to be slower than the other British entries and was relegated to a practice role.
The race would be contested over 7 laps of a triangular course alongside the Venice Lido. The order of take-off was drawn by lots and it fell to Kinkead and the Gloster to start the race producing a first lap speed of 266.5 mph. Bernardi in one of the Macchi’s flew next and immediately set a fast lap time of 275 mph. Webster’s S.5, N220, was next on the schedule, closely followed by Guazettti, Worseley and Ferrarin. The Supermarine planes were soon on the pace and closely challenging the Macchi time. Bernardi engine failed and he had to retire. His countryman, Ferrarin suffered a similar fate when his plane came down with the engine smoking. The Guazetti Macchi was left as the sole Italian challenger with any chance of beating the Supermarines. Kinkead and the Gloster, though still racing, could not match the Macchi and Supermarine speeds, and the Gloster had to retire on the fifth lap after a thin metal strip had entangled itself in the propeller. Guazetti’s Macchi suffered a punctured fuel tank and he came down in the Venice lagoon alongside the course. The two S.5’s, Lion powered, completed their full number of laps and gained first and second places. N220, piloted by Webster, took the honours, not only with a race win at 281.66 mph.
Gloster VI ‘Golden Arrow’
Gloster VI ‘Golden Arrow’ at Calshot
Two Gloster VI racers were built and registered with RAF numbers N249 and N250. Though undoubtedly fast, they proved to have fuel delivery problems when banking sharply, causing the Lion engines to cut-out. As the Schneider races were held at low altitude this posed a serious danger to craft and crew and, sadly but sensibly, the Gloster VI were withdrawn from the competition.
The Gloster VI story does not end there. The day after the 1929 Schneider Trophy ended Flight Lieutenant George Stainforth flew N249 over a measured course at Calcott to set a new outright air speed record of 336.3 mph. Two days later Augustus Oriebar retook the record for Supermarine at 357.7 mph, in an S.6 of course.
To end this article on Lion engined aircraft and the 1929 Schneider Trophy in particular I’d like to offer a couple of items of interesting trivia. One of the organizers of the Calshot event was listed as a ‘Lawrence Shaw’. This was a pseudonym for T.E. Lawrence of Lawrence of Arabia fame. The second interesting snippet relates to the Prince of Wales who attended the event. He watched the event from a motor launch piloted by Sir Henry Segrave, the driver of the land speed record winning Silver Arrow car. How good would it have been to see the other Silver Arrow competing in the air.