In January 1938 following meetings between Hawker Aircraft and the Air Ministry, and just two months after the debut of the first production Hurricane, Hawker Aircraft received details of specification F.18/37. This called for a large single-seat fighter offering a performance at least 20 per cent higher than that of the Hurricane and achieving this with the aid of one of two 24-cylinder engines in the 2,000 hp class then under development – the Napier Sabre “H” type and the Rolls-Royce Vulture “X” type. Sydney Camm had commenced investigating the possibilities of just such a fighter in March 1937, and had already roughed out a design built around the Napier Sabre engine and housing twelve 0.303-in. Browning machine guns in its 40-foot wings. At the proposal of the Air Ministry, Camm also prepared studies for an alternative version of his fighter powered by the Rolls-Royce Vulture engine.
Further discussions over military loads and equipment followed and revised tenders were submitted throughout 1938. The Air Ministry at the beginning of 1938 sought both the Type “N” and the Type “R” as the alternative Sabre and Vulture powered fighters had become known. These tenders were formally accepted on April 22, 1938, and four months later on August 30, two prototypes of each fighter were ordered. Structurally both types were similar: the wings were all-metal, the front fuselage was of steel tubing, and the aft section consisted of a stressed-skin, flush-riveted monocoque – the first Hawker designs to employ this form of construction. Uniformity between the two fighters was in fact achieved to a remarkable degree, but the designs did differ in one important respect initially – the Vulture-powered fighter made use of a ventral radiator while the Sabre driven machine had one of “chin” type.
While A V Roe continued the tooling up process for Tornado production the Vulture was effectively cancelled by Rolls-Royce in July 1941, partly due to the problems experienced in its use on the Avro Manchester, but mostly to free up resources for Merlin development and production which was starting to yield increased power output levels. However, it should be noted that the Vulture engine installation in the Tornado was relatively trouble free and the aircraft itself had fewer problems in flight to begin with than its Sabre-engined counterpart. The cancellation of the Vulture engine ended the Tornado aircraft and remaining Tornado orders were transferred to Typhoon.
However, it was quickly discovered that the Typhoon was not really suitable for its intended role, an interceptor conceived as a replacement for the venerable Hurricane. The speed with which the airframe and the new engine were rushed into service meant that frailties were found in service conditions, which more often than not resulted in fatalities. It was quite a common occurrence for the tail to become separated from the rest of the airframe, the gases from the engine leaked around the cockpit area resulting in a loss of consciousness in the pilot or the engine quite simply stopped (at the most inopportune moments). Combine this with the disappointment in the high level performance and pilots unwilling to fly the aircraft meant that the Typhoon was close to being withdrawn from service early in its career. Enter a young squadron commander (Roland Beaumont) who saw the potential for a change in its intended role to a ground attack aircraft. Its size, rugged build, its ability to carry large amounts of external ordnance and a formidable set of four 20mm cannon meant it was perfect for the role and packed a hefty punch.
A short term reprieve from cancellation meant that the major problems could be addressed. Engine seizures were subsequently found to be exacerbated when the fitters realised that they could adjust the limits for the throttle thus giving the pilot a little extra speed however; after investigation by Napier engineers on an aircraft exhibiting some unusual engine faults (It was pure luck that this aircraft was sent for investigation as it happened to have had the throttle adjusted and survived) it was discovered that this unauthorised modification weakened the engine with dramatic results. Modifications to the throttle and with Bristol ‘encouraged’ to help with the development of the sleeve valves the Sabre engine became very reliable and could regularly reach its service life without issue.
The separation of the tail from the rest of the aircraft was a more pressing issue. Pilots could deal with engine failure in normal operational conditions however; loss of the tail was catastrophic with a near 0% survival rate for pilots which meant that there were no symptoms that could be reported to Hawker engineers to enable the problem to be diagnosed. With the very real possibility that they would refuse to fly the aircraft Hawker engineers fitted fish plates to the transport joint to provide extra strength. This bought them some additional time as the number of incidents greatly reduced, but were not entirely eliminated as a result of the modification. This changed when in October 1943 a Typhoon returned from a sortie after the pilot reported severe, at times violent, elevator ‘flutter’. This information combined with the detail given by a pilot who survived the tail separating from the fuselage of a Typhoon (the only known survivor), the engineers soon realised that elevator ‘flutter’ weakened the tail which could result in failure. A redesign of the elevator mass balances and regular monitoring of the control cable runs eliminated failure’s in service. The plates added earlier in the Typhoons life were never removed, it was realised that the pilots viewed these as the reason why the failures were reduced. Removal of these plates, which did not affect the aircraft’s performance to any noticeable degree, could potentially affect pilot confidence so they were left in place with all new Typhoons continuing to have them fitted before leaving the factory.
Having overcome the initial difficulties the Typhoon eventually went on to become the backbone of the Allied ground attack force with 21 front line squadrons (plus 2 reconnaissance) across the 2nd Tactical Air Force, with a free reign (almost) to roam throughout Europe picking targets of choice. German ground movements were severely restricted, with the Typhoon operating in a ‘cab rank’ system any vehicles daring to venture out during daylight hours invariably led to them being picked off. Indeed damage was inflicted to such an extent that pilots were in danger of being shot on the spot by the Germans should they find themselves behind enemy lines.
The period between 1943 and 1945 became the pinnacle of the Typhoons career, the end of the hostilities in Europe saw the rapid withdrawal of the Typhoon squadrons back to the UK and by 1946 nearly all the remaining Typhoons were in open storage at No.5 (Kemble), No.20 (Aston Down) and No.51 (Lichfield) MU’s. At the tail end of 1946 and into 1947 the Typhoons were sold for wholesale scrapping. The last airframe, a composite, survived until 1955 when it too was scrapped at No.60 (Rufforth) MU thus seemingly committing the Typhoon to the annals of history. Fortunately, and without the RAF realising, a single airframe had been sent to the US for evaluation (MN235) which had found its way to the Smithsonian. In 1967 the RAF museum submitted a request for its return and in 1968 MN235 arrived back in the UK, Hurricane LF686 being sent in the opposite direction. So the short operational career of the Typhoon had seen an incredibly high attrition rate for pilots, which could be typical of a low level ground attack role, but had saved many thousands of allied lives and with the destruction of so much Axis armour could well have shortened the hostilities in Europe.