CHAPTER SEVEN

Hawker Tempest

The Hawker Tempest was, perhaps, what the Typhoon should have been all along. Although the Typhoon had the potential for very high performance, its relatively thick wing (19.5 per cent thickness/chord ratio at the root and 12 per cent at the tip) made for handling difficulties at the top end of the speed range, due to excessive drag rise and the formation of localised shock waves which, especially during high-speed dives, could lead to loss of control. The development of a thinner wing section as early as 1940 was considered, but it was not until the following year that work finally got under way. The thickness/chord ratio was reduced to 14.5 per cent at the wing root and 10 per cent at the tip and the maximum wing thickness now occurred at 37.5 per cent chord, instead of 30 per cent as on the Typhoon. The wing’s profile was also altered to semi-elliptical.

As the internal wing space had been considerably reduced, fuel now had to be accommodated elsewhere and the front fuselage was extended by 21 in to allow a 76-gallon tank to be inserted between the engine firewall and the oil tank, which was situated immediately in front of the cockpit. To compensate for the extended forward fuselage, a fillet was added to increase the fin area and the horizontal tail surfaces were also of increased span and chord. A revised undercarriage was incorporated, the main wheels now being fully covered when retracted. The tailwheel was also retractable. The name initially given to the new fighter was Typhoon II, but by mid 1942 this had been changed to Tempest, reflecting the large number of changes incorporated in the design. Furthermore, as the Typhoon’s future was still in doubt at the time, a change of name was beneficial in that it tended to disassociate the new aircraft from its troubled predecessor.

Continuing difficulties with the Napier Sabre engine meant that it was necessary to consider alternative powerplants, namely the Bristol Centaurus 18-cylinder radial that was under development, and the Rolls-Royce Griffon. To simplify the various engine options, Mark numbers were allocated as follows: Mark I (Sabre IV), Mark II (Centaurus IV), Mark III (Griffon IIB), Mark IV (Griffon 61), Mark V (Sabre II). In the event, neither of the Griffon-engined prototypes were completed, although one (LA610) later appeared as a Fury with a Griffon 85 and contra-props. The Tempest I was also abandoned as the Sabre IV was far from being fully developed, but only after the first flight of the prototype (HM599) on 24 February 1943. Before the axe fell, performance testing showed it to have a top speed of 466 mph at 24,500 ft, due in no small part to its reduced frontal area as a result of Sydney Camm’s decision to use wing-mounted radiators.

The first Tempest to fly was the Mark V prototype (HM595) on 2 September 1942 and the following February the aircraft was delivered to Boscombe Down for preliminary performance measurements by A&AEE test pilots. It was looked upon favourably and was considered to be manoeuvrable and pleasant to fly, although the elevator appeared to be rather heavy. A full handling assessment was carried out on the third production Tempest V (JN731) over a five-week period commencing on 25 October 1943 with a typical service loading of 11,480 lb, including service equipment and full internal fuel (132 gallons).

Entry to the cockpit was made from the starboard side and involved a certain amount of mountaineering, the pilot being provided with a foot stirrup, handhold and two retractable steps in the side of the fuselage. Access was relatively easy, although the handhold was a little on the high side and a jump was necessary to be able to reach it. The seat had a sprung back and the seating position was comfortable, with all the essential controls coming nicely to hand when the pilot was strapped in. The height of the seat could be adjusted by a lever located on the right-hand side of the cockpit. Cold air was available through two small ventilators, one on each side of the panel. Hot air was supplied via two pipes near the pilot’s feet. The aircraft was reasonably quiet in flight, although a high-pitched note or resonance was apparent, which made it fatiguing to fly for long periods. Otherwise, the aircraft was free from excessive vibration at all speeds and engine settings.

The windscreen and hood were a big improvement on the arrangement previously seen on early Typhoons. Although the windscreen had a narrower centre panel, the solid members between this and the two side panels were much thinner. The ‘bubble’ hood had no obstructions and was almost completely free from distortion, giving an excellent view in flight. On the ground, the view forwards was completely obstructed by the engine cowling, but in flight the nose attitude was well down, allowing the pilot to see directly ahead. There was no clear view panel, but the hood could be opened via a rotating lever up to 250 mph IAS, although at this speed it was not an easy task.

In an emergency, the hood could be jettisoned by pulling on a red-painted handle located to the bottom right of the cockpit, a panel in the right-hand side of the fuselage coming away at the same time. The position of the jettison lever forced the pilot to lean forward so that his head was well clear when the hood departed. Should the aircraft overturn on the ground, the armour plate behind the pilot’s head provided protection, and with the canopy open or jettisoned, it was considered that the pilot should have been able to vacate the cockpit in most normal circumstances. However, if the canopy had been locked in an intermediate position, it could not be opened from outside and it was felt that this facility should be deleted.

Ground handling of the Tempest was relatively easy; the brakes were smooth in action and turns could be made in either direction. Take-offs were normally made with the flaps in the up position, and with elevator and rudder trimmers set to ‘take-off’ and ‘full left’ respectively. With these settings, the tail could be raised quite early in the run. The aircraft tended to swing to the right, but this could be held with moderate left rudder. Stability on take-off was good, even on grass, with very little pitching being experienced, a moderate backward pressure being needed on the control column to lift the aircraft off the ground. The undercarriage could be raised immediately after take-off, producing a slight change of trim to tail heavy, but this could easily be held. The climb away was reasonably steep.

In flight, the ailerons were pleasantly light at slow speeds and on the glide, but were heavier at normal flying speed, although they remained smooth and progressive in action. Despite an increase in heaviness with speed, the ailerons could still be moved to a useful extent, even up to the limiting speed of 550 mph IAS. However, control was not good and the rates of roll obtained were fairly low. The elevator control proved to be light, effective and smooth in operation at all normal flying speeds, except on the glide with the flaps and undercarriage down, when control became less effective with rather sluggish response. The rudder was quite heavy at all times. This was not too much of a hindrance as it was little used, although it became rather more noticeable if the aircraft was out of trim directionally.

The Tempest gave the impression of being unstable longitudinally, as it required great concentration on the part of the pilot to fly the aircraft accurately fore-and-aft. This was particularly noticeable during manoeuvring flight, when it was easy to obtain higher normal accelerations than had been intended. The lightness of the elevator combined with longitudinal instability made the aircraft quite tiring to fly. At an aft CG there was no sign of tightening when carrying out a steady turn, but if the aircraft was pulled quickly into a fairly high ‘g’ turn there was a tendency to tighten, although this characteristic died away as the turn progressed and was not present at forward CG. For 4 g turns between 200 mph IAS and maximum level speed, the pull force required on the stick was light, but not unduly so for a fighter.

Longitudinal behaviour was tested at aft CG by disturbing the aircraft by about 10 mph from its trimmed speed before releasing the control column. In most conditions of flight, with the flaps and undercarriage up a phugoid of gradually increasing amplitude was noted, the only occasion when trimmed speed was regained being in the glide with the flaps and undercarriage down. With CG forward, the aircraft was slightly more stable but its behaviour was similar.

Determination of the Tempest’s longitudinal stability was not helped by a marked change in directional trim with alteration in speed and power. When power was decreased, the aircraft yawed strongly to the left, a characteristic that was also noted with an increase in speed. Because of the heaviness of the rudder control, it was almost impossible to keep the aircraft sighted on a target if the throttle was opened or closed rapidly, as might be expected in combat. It was for this reason that some lightening of the rudder was considered desirable. To make matters worse, any yaw to the left produced a nose-down pitch.

Lateral and directional stability were not tested fully, but from the flying carried out, the aircraft did not appear to have any particular problems in these respects. If a wing was depressed and the control column released, it would return very slowly to its original position, or it could be raised by use of rudder. Likewise, if the aircraft was disturbed directionally from a trimmed condition and the rudder released, it returned to its original heading.

Stall speeds with the undercarriage up and down were 85 mph IAS and 74 mph IAS respectively. Due to the aircraft’s longitudinal instability, any uncorrected backward movement of the control column produced a speed divergence towards the stall. In the landing configuration, the first warning of an approaching stall was aileron snatching, which became apparent at 95 mph IAS. This was accompanied by the port wing going down, about half aileron being required to counteract this particular tendency. At the same time, the aircraft was prone to yaw to the left, with progressive use of rudder being needed to keep straight, until about three-quarters right rudder was in use at the point of stall requiring a heavy foot load. Although the elevator control was light down to 95 mph IAS, it became progressively heavier right up to the stall, which occurred with the stick about three-quarters back from the central position. Some lateral instability was noted as the stall was approached.

With the flaps and undercarriage down, aileron snatching commenced at 80 mph IAS and was continuous below that speed. As speed was reduced, full right rudder trim and almost full right rudder was needed to hold the aircraft straight. The elevator control was light, but the response was sluggish. The stall occurred with the control column about halfway back and was characterised by a sharp yaw to the left, followed by a slight drop of the nose. The stick could be pulled back with no further effect, as the control was completely ineffective. There was no tendency to spin and the aircraft recovered immediately when back pressure on the control column was relaxed.

Dives were carried out with careful monitoring of the indicated airspeed to ensure that Mach 0.80 was not exceeded (the same limitation as that used by Hawker in their trials). This corresponded to 370 mph IAS at 30,000 ft or 540 mph IAS at 10,000 ft. The Tempest was found to be steady and smooth in the dive, with no control surface instability or buffeting. The aircraft accelerated rapidly up to 480 mph IAS, the speed then increasing slowly to a maximum of 535 mph IAS. Acceleration was dependent to a large extent on the yaw/pitch couple and any degree of mishandling could seriously affect performance. With increasing speed the aircraft tended to yaw to the left, which if not corrected fully (due to the heavy force required) resulted in a slight reduction in the push force needed on the control column to maintain balance. The rudder trimmer was extremely effective at high speed and had to be used with great care if a rapid yaw and consequent pitch was to be avoided.

When the undercarriage was lowered on the approach there was a slight nose-down change of trim, the wheels coming down unevenly, which caused some yawing and pitching. When the flaps were lowered, there was a further moderate nose-down change of trim, but this could easily be held by a backward movement of the stick whilst re-trimming. The best approach speed with the flaps and undercarriage down with the engine throttled back, was 110 mph IAS, which produced a steep glide, but with rather sluggish response to control movements. The elevator was particularly bad in this respect, which meant that it was difficult to get the tail down for landing. This characteristic was at its worst when CG was in the forward position. When the engine was used on the approach, the speed could be reduced to 90 mph IAS, the increased airflow tending to improve elevator control so that a three-point landing could be made without difficulty. The landing was straightforward, although some tailwheel shimmy was experienced when landing on grass.

If the throttle was advanced with the flaps and undercarriage down, as in the case of a baulked landing, there was a nose-up change of trim, which could be held prior to re-trimming. The aircraft also tended to yaw to the right, which needed firm pressure on the left rudder pedal. With the engine set to 3700 rpm, +4 lb/sq.in boost, the aircraft could be climbed away before retracting the undercarriage, the flaps being kept down until a speed of 160 mph IAS had been reached. When the flaps were raised, there was no appreciable sink, just a slight nose-up change of trim as also occurred when raising the undercarriage. Although the handling characteristics were generally found to be acceptable, A&AEE called for improved longitudinal stability, lighter aileron control, greater elevator effectiveness with the engine off and a lighter rudder to provide better control when confronted with the large change of directional trim with change of engine power.

Performance testing was also carried out using JN731, beginning in November 1943. Although it was fitted with a Sabre IIA of 2180 hp, the same engine as fitted to the Typhoon, it demonstrated a much-improved rate of climb and top speed. The propeller used was a four-blade, de Havilland of 14 ft diameter and the engine operating limits were: climb – 3700 rpm, +7 lb/sq.in boost (1 hour maximum), combat – 3700 rpm, +9 lb/sq.in boost (5 minutes maximum). Full climbs were made using combat power, since the rpm limitation was the same as that for normal climbing power and the combat boost restriction fell below the normal boost limit of +7 lb/sq.in well within the permitted period. The supercharger gear change was made when boost in MS gear fell to +4 lb/sq.in which occurred at 8700 ft.

With full combat power selected, a maximum rate of climb of 4380 ft/min was recorded in MS gear at sea level (full throttle height). With the supercharger in FS gear, the best rate of climb was 3000 ft/min at 13,500 ft, which was reached in 4½ minutes. Other results were as follows:

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The service ceiling was 34,800 ft with an estimated absolute ceiling of 35,600 ft. The climb rate when using normal boost rating was 3815 ft/min at sea level, with full throttle heights of 3500 ft (3815 ft/min rate of climb) and 15,800 ft (2680 ft/min rate of climb) in MS and FS supercharger.

Level speed tests showed a maximum of 432 mph TAS at 18,400 ft, which was approximately 20 mph faster than the best speed recorded on a Typhoon. The full results were as follows:

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The full throttle heights as tested were thus 6600 ft and 18,400 ft, which were approximately 4–500 ft higher than expected, as full combat boost was not obtainable due to slight inaccuracies of the automatic boost control. The top speed was not affected.

Heavy lateral control at high speed was greatly improved with the introduction of spring-tab ailerons. Although it was still outclassed by the Fw 190 and Mustang in terms of rate of roll, at speeds above 350 mph IAS the Tempest was superior to the Spitfire. Reduced wing thickness compared with the Typhoon contributed to a significant improvement in dive and zoom climb capability, acceleration in the dive being one of the Tempest’s greatest advantages. It was also an excellent gun platform due to its steadiness in an attacking dive. At low to medium levels few aircraft could stay with a well flown Tempest V and comparative trials carried out at AFDU showed it to be 15–20 mph faster than the Mustang III and Spitfire XIV up to 15,000 ft. Above this height, its superiority was gradually reduced and above 25,000 ft both the Mustang and Spitfire were faster.

The Tempest V was introduced to RAF service by No. 486 Squadron in early 1944, which together with Nos 3 and 56 Squadrons, formed the Newchurch Wing under the leadership of Wing Commander Roland Beamont DSO DFC. The Tempest V’s low-level speed performance was put to good use during the V-1 flying bomb campaign, destroying a total of 638, representing 36 per cent of the RAF’s total claims. The Tempest was widely used by 2nd Tactical Air Force in support of the Allied advance in northern Europe, its main duty being to achieve low-level air superiority so that the fighter-bombers could go about their business without interference from the Luftwaffe. When the opportunity arose, armed reconnaissance missions were also flown, looking for suitable targets well behind the front line. The Tempest V was one of the most deadly low-level fighters of the late war period and was responsible for destroying twenty Messerschmitt Me 262 jet fighters in air combat.

While the Tempest V was entering service, the Tempest II was being tested at Boscombe Down. The prototype (LA602) was flown for the first time on 28 June 1943 and was followed into the air by LA607 on 18 September 1943. Like the prototype Tempest V, a Typhoon tail was initially fitted but a revised fin with dorsal fillet was soon added. Power came from a 2520 hp Centaurus IV. The airframe was basically the same as that of the Tempest V, except for a revised forward end to accommodate the new engine, with air intakes in the leading edges of the wings for the carburettor and oil cooler. Following development delays with the Centaurus XII, which had been the preferred engine for production aircraft, plans eventually centred on the Centaurus V.

Performance and handling trials were carried out on LA602 at Boscombe Down in early May 1944. The noise level of the Tempest II was considerably lower than the Mark V, which made it much less tiring to fly. However, there was excessive vibration throughout most of the rpm range. At engine speeds above 2400 rpm a harsh high-frequency vibration developed, which worsened with increasing rpm up to the maximum of 2700 rpm. Below 2000 rpm a similar vibration occurred, which reached its peak at 1750 rpm and then fell off rapidly as engine revs were reduced. The vibrations tended to increase with the application of normal accelerations, but were not greatly affected by changes in speed. At speeds above 200 mph IAS buffeting was also experienced when the cooling gills were fully open, which felt very like the engine vibration.

The pilot’s throttle control received mixed reviews. It was rated better than that on the Mark V, being easy to move without any tendency to slip, but the ‘gates’ on the quadrant, which were meant to indicate the positions for cruising, rated and take-off boost, could barely be felt. The forward view on the Tempest II was slightly worse than the V due to the wider nose and the undercarriage also seemed less smooth, especially when taxying on rough ground. The take-off was similar to the Tempest V, but in the climb there was insufficient left rudder trim available to fly ‘feet off’ below 210 mph IAS, though the foot loads were not large. The best climbing speed was 190 mph IAS.

General flying showed the ailerons to be even heavier than on the Mark V. The rudder was moderately light for small deflections, becoming heavier when moved through greater angles. Although similar to the Tempest V, the fact that changes in directional trim with speed and power were less marked, meant that the pilot did not have to re-trim directionally during manoeuvres at cruising speeds, though it was still necessary at high speeds. A degree of longitudinal instability was still present in the Tempest II when flown at the normal full service load of 11,360 lb (aft CG), although any deviation from steady trimmed flight was not rapid if flown ‘hands off’, the aircraft being rated as easy to fly. No tightening was experienced in turns, even when the aircraft was pulled quickly into a turn. Similarly, recoveries from trimmed or out-of-trim dives did not produce excessive accelerations, unless they were induced by the pilot due to the light elevator forces present. It was, however, considered that some improvement in longitudinal stability still needed to be made, in case CG was moved further aft in service when carrying additional loads.

The stalling speeds for the Tempest II were virtually identical to the Mark V, the actual results with the flaps and undercarriage up and down being 86 mph IAS and 75 mph IAS respectively. The approaching stall was announced by gradually increasing buffet and although the port wing usually dropped, on occasions the starboard wing would go down. Recovery was immediate on pushing the control column forward and there was no tendency to spin. Although the limiting speed in the dive was 580 mph IAS, tests were only carried out to 515 mph IAS owing to a cracked hood. All the controls became heavier, particularly the ailerons, and like the Tempest V, the aircraft yawed to the left with a nose up pitch, although this particular characteristic did not appear to be quite as pronounced. If the control column was released at high speed, the aircraft continued in the dive, which was only to be expected as no force was needed to maintain the desired attitude.

The recommended approach speed was 100 mph IAS, but if the aircraft was held off too high on landing the right wing tended to drop quite sharply as the aircraft stalled. Once again, with the engine off there was insufficient elevator control to achieve a three-point landing, although this situation was improved slightly by using a little engine to improve the airflow over the tail to generate improved effectiveness. The approach and landing had to be made with the cooling gills closed, as the stall speed was around 5–7 mph higher with them open and there was a further reduction in elevator effectiveness.

Climbing performance at combat power showed further improvement over the Tempest V, the Mark II taking 2½ minutes less to get to 30,000 ft. The full throttle heights in MS and FS gear were 5000 ft and 14,900 ft, with rates of climb of 4400 ft/min and 3220 ft/min respectively. Other results were as follows:

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The increase in level-speed performance was slightly more modest, with a maximum of 440 mph TAS at full throttle height in FS gear of 17,500 ft. The best speed achieved in MS supercharger was 422 mph TAS at 8400 ft, with the gear change being made at 13,700 ft. The full results were as follows:

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The problem with excessive vibration was eventually overcome by the use of flexible engine mounts in place of the original rigid mounting and, on later aircraft, by the use of a five-blade propeller. As the Tempest II had been selected for use in the Far East, tropical trials were carried out at Khartoum in April 1945. Shortly after, MW754 was delivered to the Air Fighting Development Squadron (AFDS) at Tangmere for a full tactical evaluation.

The take-off weight with full internal fuel and ammunition was 11,700 lb, which resulted in a wing loading of 38 lb/sq.ft, the same as for the Tempest V. The Centaurus V developed 2300 hp at 2700 rpm and +8 lb/sq.in boost in MS gear at 5000 ft and 1950 hp at 16,500 ft in FS gear. The maximum power (2700 rpm and +12 lb/sq.in boost) at sea level was 2650 hp using 150-octane fuel. The power was transmitted through a 0.4 to 1 reduction gearing to a four-blade Rotol metal propeller of 12 ft 9 in diameter. Cooling air for the engine entered between the cowling and the spinner (no cooling fan was employed) and exited through adjustable gills on each side at the rear of the engine.

Fuel was carried in four self-sealing tanks. The main tank in the fuselage, just aft of the forward firewall, held 76 gallons and was augmented by two inter-spar tanks, one in the inner portion of each wing, containing 28 gallons and a nose tank in the port wing with a further 28 gallons, giving a total fuel capacity of 160 gallons. The armament was similar to the Tempest V and consisted of four wing-mounted 20-mm Hispano cannon. Each gun had its own ammunition box, the inboard guns having 162 rounds, with 156 rounds for the outer guns. They were controlled electro-pneumatically from a push switch on the spade grip of the control column and could be fired all together, or in pairs. Pressing the top of the button fired the inboard cannon, the bottom fired the outer guns and all four were fired by pressing the centre of the button. At the time of test, MW754 was fitted with a GM.2 reflector gunsight.

A number of flying limitations were in place at the time of test. As the aircraft was fitted with an underwing pressure head instead of a pitot mounted in the leading edge of the wing, the maximum speed was limited to 520 mph IAS. Intentional spinning was prohibited and the aircraft was restricted to a speed of 300 mph IAS with the hood open. Although drop tanks of 45-gallon capacity had been cleared by A&AEE up to 450 mph IAS, the larger 90-gallon tank had still not been approved.

Ground handling was straightforward and as the aircraft was tail-heavy, the tail showed no inclination to lift, even when taxying over rough surfaces. The brakes were extremely powerful and had to be handled with care. The forward view was considered to be slightly worse than that from a Tempest V. On take-off, full port rudder trim was needed and the throttle opened slowly as the aircraft tended to swing to starboard. Although the swing was a little worse than the Tempest V, it could easily be held with rudder. At an engine setting of +8½ lb/sq.in boost and taking off into a headwind of 10–15 mph, the run was approximately 350 yards. The aircraft became airborne at around 100 mph IAS, but there was a tendency for the starboard wing to drop if pulled off too early.

The best technique for landing was to leave a small amount of power on, as in a glide there was insufficient elevator authority to allow a three-point touchdown to be made. Although A&AEE had warned that the right wing was liable to drop if the aircraft was held off too high, AFDS found the landing to be normal. After touchdown a swing to the left was the most likely outcome, however, this could easily be controlled by using the brakes, provided care was taken not to over-correct.

General handling tests showed the elevators to be the lightest of the three controls and they were adequate at all times except in a glide landing. The rudder was described as ‘pleasantly heavy’, its action was positive and it required less re-trimming than the Tempest V with changes in speed and power. The ailerons were also quite heavy, but the response was immediate throughout the speed range. It was felt that some more port trim was needed for take-off and there was also insufficient port trim to be able to fly ‘feet off’ when carrying out a maximum rate climb.

The Tempest II proved to be slightly unstable in pitch at heights above 15,000 ft at all speeds. In a tight turn there was a tendency for the aircraft to tighten up, especially at altitude, but this characteristic was not sufficiently pronounced as to cause the pilot any real embarrassment. The aircraft was stable directionally. Generally, the Tempest II was easy and pleasant to fly. There was plenty of warning of a high-speed stall, with increased buffeting and aileron snatch. Some problems were experienced with high oil temperatures during prolonged climbs, or when operating at high throttle settings for any length of time. Pilots also had to monitor the cylinder head temperature gauge closely, as certain combinations of mixture strength and boost were liable to cause detonation, although generally the Centaurus engine was found to be extremely reliable. Between 1600–2000 rpm, and to a lesser extent at maximum power, considerable vibration was experienced. However, it was not of sufficient intensity as to cause any serious mechanical problem, although it was annoying for the pilot and tended to affect his ability to hold his sight on a target.

No difficulties were encountered during low-flying or aerobatics and the nose did not wander when manoeuvring in the rolling plane. Formation flying was straightforward as regards general handling, although the rough running of the engine as mentioned above meant that pilots were either throttling back to avoid the period, or opening up beyond it. Under these conditions, aircraft in formation were either going too slow or too fast and constant throttle juggling was necessary. If the rough-running was found to be too fatiguing over a long period and the pilot increased engine revs to 2000 rpm by moving the propeller control lever forward, this had the effect of reducing range by around 10–15 per cent.

The Tempest II was also flown at night and pilots commended its almost total lack of exhaust glare. The only difficulty was its inclination to swing on landing, which was not dangerous to a pilot who had flown the aircraft and was aware of this particular characteristic. One aspect of the Tempest II that needed improvement was a lack of ventilation in the cockpit, especially at low altitudes. This was a particular concern as the aircraft was intended for use in the Far East. When taxying, exhaust fumes also tended to seep into the cockpit, a problem that had been around for a long time, going back to the early days of Typhoon development.

The Tempest II was flown against a Tempest V for a tactical comparison. Consumption tests were carried out, which showed that the Tempest II had a very similar radius of action to that of the Mark V. On average, the Tempest II was 15 mph faster than the Mark V, the advantage varying from 10–20 mph depending on height, and this could be maintained up to the aircraft’s operational ceiling, which was considered to be 30,000 ft (the level at which the climb rate fell below 1000 ft/min). In terms of acceleration, the Tempest II was markedly superior when opening up from cruising speed to full throttle and it pulled away rapidly. The Tempest II could also climb at a better rate, being 350 ft/min better up to 3000 ft, but by the time that 8000 ft had been reached its advantage was 1000 ft/min. This figure had dropped once again to 400 ft/min by 12,500 ft, but this could be maintained up to the service ceiling.

In zoom climbs at equal power settings the two aircraft were very similar, but at full throttle the extra power of the Centaurus gave the Tempest II a definite edge. The dive performance was virtually identical and there was little to choose between the two as regards turning circles, although if anything the Tempest V had a slight advantage. During the trials, the rate of roll of the Tempest II was shown to be better than that of the Mark V, although as the two aircraft shared the same airframe there was no aerodynamic reason why this should be so. It was assumed that the ailerons on MW754 were performing above the average and might not be representative of production aircraft.

The Tempest II was highly commended by AFDS, as its very high speed had been achieved with moderate wing loading so that a high degree of manoeuvrability had been retained. The fire power of the Tempest II was formidable as a result of the increased rate of fire of the Mark V 20-mm Hispano cannon and, if required, a bomb could be carried under each wing. There was also provision for the carriage of RP. Like all high-powered, single-engine fighters (without contra-props) it was sensitive to changes in speed. This meant that the pilot had to continually trim the rudder, or apply heavy foot loads to prevent skid, which was the major source of inaccuracy during ground-attack sorties.

The Centaurus engine performed well during the trials and was extremely reliable. As an air-cooled engine it was well suited to the Tempest II, which was intended for use in South-East Asia Command in the low-to medium-level air superiority role and for ground attack, as it would have been less vulnerable to ground fire than equivalent liquid-cooled engines.

Relatively few recommendations were made. Although the armour protection for the pilot (and vulnerable parts of the engine) was considered adequate for air combat, ideally, more was required to protect against ground fire. A fully automatic carburettor control to maintain the correct mixture between economical cruising and rated boost was urgently needed to reduce the pilot workload. It was also felt that the lack of a rack under the centreline for a bomb or drop tank was a major omission. A contra-rotating propeller to remove the need for directional trim changes due to alterations in speed would have been nice. Failing that, however, a rudder trim indicator, along the lines of that developed for the Spitfire, would have allowed the pilot to pre-select his rudder trim with reasonable accuracy before going in to a dive.

The Tempest II entered service with No. 54 Squadron at Chilbolton in November 1945 and was also flown by No. 247 Squadron at the same base. It was used by three squadrons attached to BAFO in Germany (Nos. 16, 26 and 33) and by four squadrons in India (Nos 5, 20, 30 and 152). Despite the fact that the Tempest II was to have been used in the Far East, only one unit was to fly it in this region, No. 33 Squadron, which transferred from Gutersloh to Kai Tak in July 1949. Here, it was used on anti-terrorist operations armed with rocket projectiles, until it was replaced by twin-engined de Havilland Hornets in 1951. Production of the Tempest II totalled 472, of which 422 were built by Hawker and fifty by Bristol.

The last Tempest was the Mark VI, which was powered by a Sabre V of 2340 hp. The prototype was HM595, which was converted and flown for the first time in its new guise on 9 May 1944. To provide greater cooling the carburettor intake was repositioned in the wing leading edge, the freed up space in the nose scoop allowing a larger radiator. The oil cooler was also moved to a position behind the radiator, but tropical trials showed a need for additional oil cooling, which was provided by a subsidiary unit located in the leading edge of the starboard wing. The maximum speed was 438 mph TAS at 17,800 ft and service ceiling was estimated at 38,000 ft. The Tempest VI was used in the Middle East, where it was flown by Nos 6, 8, 39, 213 and 249 Squadrons, all the remaining aircraft being withdrawn in early 1950.

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1. Hurricane prototype K5083 being flown by P. W. S. Bulman in its original form with strutted tailplane, retractable tailwheel and unstiffened canopy. (Author)

2. A later view of K5083 with modified conopy, cantilever tailplane and radio mast. The stub exhausts are shown to advantage. (Philip Jarrett)

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3. Hurricane IIB BN114 carrying two 500-lb bombs. The aircraft is fitted with twelve 0.303 in. Browning machine-guns and features an internal bullet-proof windscreen, triple ejector exhausts with fishtails, a rear-view mirror, a snowguard over the air intake and an oil slinging ring on the front of the cowling.

(Philip Jarrett)

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4. Hurricane IIA Z2515 seen at A&AEE Boscombe Down in February 1942.

(Philip Jarrett)

5. The last Hurricane ever build was

PZ865 ‘The Last of the Many’. It still flies wiith the Battle of Britain Memorial Flight at Coningsby.

(Author)

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6. The largest calibre weapon carried on any RAF single-engine fighter was the Vickers 40-mm ‘S’ gun, seen here mounted under the wings of Hurricane IV LB774. The top speed was reduced to around 290 mph but the aircraft proved to be effective in the tank-busting role in the Middle East and in Burma.

(Philip Jarrett)

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7. Spitfire IX ‘BF274’ was actually BS274 and was a converted Mark V, which was used on various performance trials at Boscombe Down, including comparative assessments of high and low altitude versions of the Merlin 61 series engine. (Philip Jarrett)

8. Following a force-landing on 22 March 1937,

K5054 was modified to Mark I standard and repainted in standard camouflage colours as seen here. It was fitted with a Merlin II with ejector exhausts, which increased speed to 347 mph at 20,000 ft. (Philip Jarrett)

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9. The clean lines of the prototype Spitfire are immediately apparent in this view of K5054. It is still fitted with small wheel doors to the undercarriage legs, but these were soon deleted. (Author)

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10. The Griffon was introduced to operational use by the Spitfire XII, its single-stage supercharged engine excelling at low level. MB882 flew with No. 41 Squadron before ending its days at the Fighter Leader School at Milfield. (Author)

11. Spitfire XIV RB146 seen during trials at Boscombe Down with a rudder guard for spin tests at various CG loadings.

 (Author)

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12. Spitfire F.21 LA188 was used for high-speed trials and was dived to Mach 0.89 during investigations into compressibility. This work continued after the war and the aircraft was eventually struck off charge on 16 June 1954. (Philip Jarrett)

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13. The Defiant II prototype N1550 seen during testing at Boscombe Down with a tropical oil cooler in an enlarged fairing under the nose. (Philip Jarrett)

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14. The prototype Defiant K8310 in natural metal finish and without the turret, which was still being tested in Overstrand K8175. Ballast was fitted to maintain the correct CG position. (Philip Jarrett)

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15. Defiant I N1551 was converted to a Mark II and was used at Boscombe Down for performance and handling trials. It survived until 14 February 1943, when it was abandoned after control was lost.

 (Philip Jarrett)

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16. K8620 was the second Defiant prototype and was flown for the first time on 18 May 1938. (Philip Jarrett)

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17. The first prototype Skua I, K5178, seen at Brough in 1937. On completion of its allotted test schedule the aircraft was used for ditching trails from HMS Pegasus in February 1939.

(Philip Jarrett)

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18. Skua II L2883 was the first aircraft to be fitted with an arrester hook and also featured a modified tailwheel oleo to prevent juddering. It was delivered to Worthy Down on 10 January 1939. (Philip Jarrett)

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19. Skua I K5179 was the second prototype and featured the extended nose, which increased its length by 2 ft 4¾ in. It is seen here at Brough in May 1938 with Flight Lieutenant Henry Bailey, Blackburn’s chief test pilot, in the cockpit. (Philip Jarrett)

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20. A formation of Blackburn Rocs in echelon stardoard. The aircraft are fitted with ligth series bomb carriers under the wings. (Philip Jarrett)

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21. Blackburn Roc L3084 was delivered to 27 MU Shawbury on 31 August 1939 and was subsequently converted to a target tug. . (Philip Jarrett)

22. The first production Fulmar N1854 was used for performance and handling trials at Boscombe Down. On its return to the manufacturers, it was modified as a Mark II and it is currently preserved at the Fleet Air Arm Museum at Yeovilton. (Philip Jarrett)

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23. Another early production Fulmar, N1858 undertook speed trials at Boscombe Down before being used by Fairey to test double-split flaps and geared tab ailerons. It was later fitted with powered ailerons similar to those intended for the Fairey Spearfish torpedo/ dive-bomber. (Philip Jarrett)

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24. N1855 was also involved in the test programme at A&AEE and was used for diving trials. (Philip Jarrett)

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25. A Fulmar II, possibly N4021. The fitting of the 1300 hp Merlin XXX required a revised Rotol propeller, a new radiator and oil cooler, and revisions to the fuel system. The aircraft also had a modified rudder mass-balance. (Philip Jarrett)

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26. The prototype Tornado P5224 is easily identified by the twin exhaust stacks of its Rolls-Royce Vulture 24-cylinder ‘X’ engine. It is seen here at Boscombe Down in October 1941.

(Philip Jarrett)

27. Typhoon prototype P5212 pictured at the Hawker airfield at Langley soon after roll out. It has the original small tail and triple exhaust stubs. The lack of rearwards view was criticised during initial trials at A&AEE. (Philip Jarrett)

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28. Tornado P5224 in the air. No guns were fitted during the trials at Boscombe Down, ballast being added to obtain the correct weight. (Philip Jarrett)

29. Typhoon R7579 was the third production aircraft and features the enlarged tail and revised exhaust stacks. It was used by Hawker before being struck off charge on 1 April 1943.

(Philip Jarrett)

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30. JR128 of No. 183 Squadron shows the Typhoon in its final form, with fully blown hood and whip aerial. It later flew with No. 181 Squadron and was shot down by flak at Livarot near Falaise on 18 August 1944. Flt Lt W. Grey baled out and became a PoW. (Author)

31. Typhoon IB EK183 displays black and white underwing identity stripes and a white cap to the spinner. These markings were one of several attempts to avoid ‘friendly fire’ incidents, owing to the Typhoon’s similarity from certain angles to the Focke-Wulf Fw 190. EK183 flew with Nos 56 and 609 Squadrons and eventually became instructional airframe 5232M.

(Philip Jarrett)

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32. EJ846 was one of 305 Tempest V aircraft of the second production batch produced by Hawker in 1944. It was eventually converted to a target tug and was still inwas use at Sylt in 1954. (Philip Jarrett)

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33. Tempest V prototype HM595 seen at Langley in September 1942 with a Typhoon canopy and tail unit. (Philip Jarrett)

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34. The prototype Tempest II LA602 at Langley in June 1943, fitted with a Typhoon tail unit.

(Philip Jarrett)

35. Tempest V NV768 was fitted with an experimental annular radiator and is seen here with Tempest VI NX121. (Philip Jarrett)

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36. Formerly of II/JG 54, Messerschmitt Bf 109E-3 AE 479 was captured by the French and subsequently tested in the UK at Boscombe Down and Farnborough. It was shipped to the USA in June 1942. (Philip Jarrett)

37. DG200 was a Bf 109E-4 and was used for a comparative assessment against the Spitfire and Hurricane. It is seen here being flown with the canopy removed. (Philip Jarrett)

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38. The Bf 109G or Gustav was built in greater numbers than any other variant and was powered by a Daimler Benz DB 605A of 1475 hp. (Philip Jarrett)

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39. Another captured Bf 109, NN644 is an ‘F’ model, which is readily identifiable by its rounded wing tips. (Philip Jarrett)

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40. Len Thorne of AFDU posed with Bf 109G TP814 after his take-off accident on 22 November 1944 at Wittering. (Author)

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41. Focke-Wulf Fw 190A-3 Werke Nummer 313 shortly after its arrival at Pembrey on 23 June 1942. Its subsequent evaluation confirmed that is was superior to the Spitfire V in nearly all aspects of performance. (Author)

42 The Pembrey Fw 190 after the application of RAF markings and with the serial number MP499. (Author)

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