Let Let Let – Warplanes

After the 1923 Schneider Cup contest it was evident the Supermarine Sea Lion III was at the end of its development. With the U.S. Curtiss racers as winners of that year, it was evident the Mitchell’s design team at Supermarine had to come up with a completely different design as a possible winner. With the Sea Lion I, II and III known at Supermarine as the types S.1, S.2 and S.3, the new racer received the type designation S.4. It was a mid-wing cantilever monoplane fitted on two floats fitted with a Napier Lion VII engine producing 700 hp . The S.4 was largely constructed of wood. For the 1925 event in Baltimore one was built. Although the military serial N197 was assigned to the S.4, this was never painted on the fuselage. For the race it was painted glossy white while the metal parts around the engine we kept in bare metal finish. Except for the racing number 4 on both sides of the fuselage, it only carried the Union Jack flag on its rudder.

The S.4 was completed in five months time only, making its first flight on 25 August 1925 from Calshot naval air station. Pilot on this occasion was Henri Biard. The flight tests revealed that the S.4 was capable of reaching speeds of more than 360 km/h which was promising enough to enter the machine in the race at Baltimore with Biard as pilot. Unfortunately, Baird already crashed before the race at a high speed run when excessive wing flutter made the racer uncontrollable. Luckily, he survived the crash although he was almost drown.

After the failure of the S.4 Mitchell’s team started with a successor based on all the hard lessons learned from this unlucky Schneider Cup racer. An extensive wind-tunnel program was run to find out the most efficient airframe for the new racer for the next event in 1927. Designated as the Supermarine S.5, Supermarine designed and built an all-metal braced low-wing racer with a Napier Lion engine up-rated to 900 hp. For cooling, extensive use of surface radiators was made with coolers fitted not only on the fuselage, but also on the wings. Three S.5 racers were built, receiving the serial numbers N219, N220 and N221. N219 had a direct-drive engine while the other two had geared Lion engines giving some 25 hp less on the propeller. The first S.5 made its maiden flight on 7 June 1927, flown by Fl. Lt. O.E. Worsley.

Flight testing progressed without major problems and for the Schneider Cup race at Venice in September 1927 N219 and N220 were shipped to Italy and entered into the race. Both S.5′s were unbeatable and Ft. Lt .N. Webster followed by Ft. Lt. O.E. Worsley finished first and second with respectively the direct-drive N219 and the geared N220. Unfortunately, Ft. Lt. S.M. Kinkead was killed in N221 on 12 March 1928 when he tried to set a world speed record.

As a back-up plane for the 1927 race in Venice, Shorts had built a simple low-risk racer fitted with the very reliable Bristol Mercury I radial air-cooled engine of 960 hp. Named Crusader, it was mainly constructed of wood with a very characteristic broad-chord elliptical shaped wing. The Crusader was completed by 18 April 1927 and test flown on several occasions by a number of pilots. However, it met disaster on 11 September when test pilot H.M. Schofield discovered shortly after the start that the controls did not function properly. Schofield crashed it into the water, but fortunately he survived with only a number of painful bruises. The direct reason for the crash was discovered when the wreckage was salvaged and investigated: the control cables for the ailerons were crossed!

Based on the earlier Gloster IV biplane, Henry Folland’s team designed an even more refined biplane racer for the next Schneider Cup event as the Gloster V. However, since the racing results obtained with the Gloster IV clearly showed the days of the biplane were over, it was never built. Instead, Folland designed a braced low-wing monoplane racer with a very sleek fuselage as the Gloster VI. In fact, this type bore a close resemblance to the successful Supermarine S.5! Two Gloster VI racers were built for the 1929 race. The Gloster VI was of mixed construction. Fuselage and floats were made from duralumin while the wings were made of wood. They received the serial numbers N249 and N250. Both machines were supplied to the RAF High Speed Flight at Calshot in August 1929. However, testing went very slowly, not only because of the bad weather, but also because of the fact that the Napier Lion engines refused to run properly at full power. With a power output of 1320 hp it was evident this engine was at the end of its development! Since the engine problems could not be solved in time, both Gloster VI racers were eventually withdrawn. A day after the race, Ft. Lt. Stainford tried to settle a new world-speed record with N249. At last, the Lion worked satisfactory at full power and at a 3 km course, Stainford set a new record of 538 km/h. However, only half an hour later Sq. Ldr. Orlebar broke it already in the new Supermarine S.6! After the event, both Gloster VI’s were used as trainers by the High Speed Flight, but they were only flown on a very limited scale.

For the Napier Lion powered Supermarine S.5 it was more or less evident that this engine was at the end of its development and that a new high-powered engine was needed to win the Schneider Cup event. When Rolls Royce offered their new racing engine Type “R” to Mitchell’s team, Supermarine started with the design and construction for a suitable airframe for this engine. Type “R” was a large twelve cylinder liquid-cooled V6 engine producing 1900 hp. The Rolls Royce “R” was larger than the earlier Napier Lion and as a consequence the fuselage of the new racer, designated as the S.6, was somewhat larger than that of the S.5. For the rest, both types were more or less similar although the S.6 also had slightly larger floats.

For the 1929 Schneider Cup race two S.6′s were built, carrying the serial numbers N247 and N248. Both machines were painted in a very attractive blue and silver colour scheme. The S.6 N247 was flown for the first time on 10 August 1929 by Sq. Ldr. A.H. Orlebar. On 25 August 1929 Orlebar made the first flight in N248. Both machines handled very well and fully met the expectations for speed! Both machines were entered in the 1929 race and both planes finished first and second so it seemed. They were flown by Fl. off. H.R. Wagman and Fl. Off. R.L.R Atcherly at an average speed of respectively 528.9 and 523.9 km/h. Unfortunately, Atcherly was disqualified after the race for cutting a pylon, but at least, the U.K. had now won two respective races and only needed a third to come in the final possession of the trophy!

For the next race in 1931, financials seemed to prevent them from being held. Both Italians and Americans had already announced that they had no racers available in time for this event and when the RAF staff declared they saw no further use in the development of these highly specialized seaplanes it was almost the end of the race of that year. Fortunately a wealthy widow, Lady Houston, gave sufficient financial back-up to prepare two S.6′s for the race. They were fitted with more powerful Rolls Royce “R” engines producing 2350 hp. Designated as the S.6B and fitted with serial numbers S1595 and S1596 they were both entered in the race, but eventually only S1595 flown by John Boothman entered the race as only participant. He finished with an average speed of 547 km/h and finally won the trophy for the U.K.! After the race, the S.6B S1595 established a new world speed record of 655.8 km/h. It was flown by ft. Lt. G.H. Stainford on 29 September 1931. On this occasion the engine was further boosted until it produced 2600 hp. The S.6B S1595 is now exhibited in the Science Museum in London.

Related posts:

1. Tangmere Military Aviation Museum
2. Caudron C.460 Rafale replica presented at Le Bourget
3. Vickers Supermarine Type 381 Seagull ASR-1
4. Dutch flying boats and amphibians

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