18. Detailed investigations have been carried out into compass deviation on this aircraft, and the results published in A. & A.E.E. report No. 807a, Part 4, dated 28th August, 1944. If the aircraft is to be correctly navigated over large featureless spaces, the deviation errors reported must be remedied.
HANDLING ON THE GROUND
19. Taxying is straightforward and the aircraft is tail-heavy and the tail shows no tendency to lift. The brakes are powerful and should be handled with reserve. The view from the cockpit is not quite so good as from the Tempest V, and care should be taken when taxying on narrow perimeter tracks or in the vicinity of obstacles.
HANDLING IN THE AIR
20. Full port rudder trim should be used, and the throttle opened slowly as the aircraft tends to swing to starboard. The swing is slightly worse than on the Tempest V, but can be easily controlled on the rudder. At an engine setting of +8 ½ lbs. boost, taking off into a wind of 10 -15 m.p.h. the take-off run from runways is approximately 350 yards. The aircraft unsticks cleanly at 100 A.S.I. There is a slight tendency for the right wing to drop if the aircraft is "pulled off" too early.
21. The actual landing, if made with a little motor, is normal. A. & A.E.E. state that the right wing may drop of the aircraft is held off to high. The elevator control is not sufficient in a glide landing to make a three-point touch down. On aircraft fitted with the automatic gill and oil cooler shut as the stalling speed is increased by some 5 m.p.h. with the oil cooler open. After touch-down the aircraft displays a tendency to swing to port. This can be controlled on the brakes but care should be taken to avoid over-correction.
22. The rudder is pleasantly heavy and positive. Less re-trimming than on the Tempest V is necessary with changes in speed and power.
23. Aileron control is rather heavy, but the response is positive and immediate throughout the speed range. Aileron control should be comparable to the Tempest V but it will be found to vary from aircraft to aircraft.
24. The elevator control is moderately light and is adequate for all flying except as previously stated in a glide landing. Changes of speed and power have less effect on the trim of the aircraft than on the Tempest V or other contemporary British fighter.
25. Trimming tabs are provided for rudder and elevators. In flight, less re-trimming is necessary than on the Tempest V, but a little extra port trim would be an advantage for take-off. There is also insufficient port trim to be able to fly 'feet off' when climbing under maximum conditions.
26. The Tempest II is slightly unstable in pitch at heights in excess of 15,000 ft. at all speeds. In a tight turn there is a tendency for the aircraft to tighten up especially at altitude. Neither of these characteristics is sufficiently pronounced to cause embarrassment to the pilot. The aircraft is stable in the yawing plane. At all times the aircraft is very pleasant to handle and easy to fly. The usual warning of the high speed stall is given by pronounced buffeting and aileron snatch. The general impression is that the Tempest II handles better that the Tempest V.
27. The interconnection of throttle and pitch is simple to operate. The present oil cooling system is unacceptable for operational use, as high oil temperatures are experienced in prolonged climbs, or prolonged periods at high throttle settings. Throttle settings between economical cruising boost and rated boost gates should be avoided where possible as the combination of mixture strength and boost at these settings is liable to cause detonation and high cylinder temperatures. Should operational conditions demand their use, for example formation flying, a close watch should be kept on the cylinder head temperature gauge.
28. Between 1600 and 2000 r.p.m. and to a lesser extent at maximum power, there is a considerable vibration, but there is no indication that this vibration is likely to cause damage to either the airframe of engine. In fact the Centaurus has been found to be most reliable mechanically.
Search and Sighting View
29. The all-round search view from the pilot’s cockpit is good, though forward view has suffered slightly by the fitting of the radial engine. The sighting view over the nose gives 4°, which is identical to the Tempest V.
30. The Tempest II is a pleasant aircraft for low flying.
31. The Tempest II is excellent for all aerobatic manoeuvres and there is no tendency for the nose to wander when manoeuvring in the rolling plane.
32. As far as handling the aircraft is concerned formation flying presents no special difficulties. Engine handling requires considerably more care, as, when formatting at low airspeeds (200 – 240 I.A.S.) it is impossible to avoid a rough period between 1600 and 2000 r.p.m. and the pilot is either throttling back to avoid the period or opening up beyond it. Under these conditions the aircraft is going too slow or too fast, and constant juggling with the throttle is necessary.
Range and Endurance
33. To obtain maximum benefit from the interconnection of pitch and throttle, the pitch control should be kept in the automatic position. This may however result in pilots having to pass through the rough period to maintain formation when flying at economical throttle settings. Should it be found to too fatiguing, the r.p.m. may be increased to 2000 r.p.m. by moving the propeller control lever forward but this will reduce the range by 10 – 15%. If the r.p.m. are increased the boost should be reduced or else the range will be cut down still further. The final decision on this matter can only be taken by the Squadron or Wing Leader in the light of operational experience with the aircraft.
34. The height at which the rate of climb fell below 1,000 ft. per minute was 30,000 ft.
35. The Tempest II is an extremely pleasant fighter for night flying and should offer no difficulties apart form the tendency to swing after landing, with which pilots experienced in day flying will be thoroughly familiar. The almost total absence of exhaust glare is a particularly pleasant feature of this aircraft.
36. The Tempest II is pleasant and straightforward for instrument flying.
37. The gun sighting platform qualities of the Tempest II are good, but the vibration periods already referred to in para. 29 must be avoided as the sight movement under these conditions is detrimental to sighting accuracy. It is not known what effect this will have on the Gyro Gun Sight.
38. There is insufficient ventilation in the cockpit especially at low altitudes, even in temperate climatic conditions. When taxying there is a considerable amount of exhaust fumes in the cockpit. It is understood that punkah louvers will be fitted on later models to improve the ventilation in the air.
Armament and Harmonization
39. The four Mark V Hispano guns are equipped with No. 4, Mk. II, Front Mounting Units. The Mark V Cannon has no cocking cylinder, but a detachable hand operated cocking unit is provided in its stead, the stowage for this being in the port wheel well. The installation is accessible for maintenance and removal and replacement of guns is simple.
40. The front mountings are inaccessible, but to overcome this difficulty, special adaptors are provided for hamonisation purposes. Harmonisation was carried out in accordance with Headquarters, A.D.G.B. Diagram No. Arm/TE.101 dated February, 1944.
Gun Firing and Bullet Pattern
41. The bullet pattern has been published in the Headquarters Fighter Command Armament Staff Instruction, Part I, Section ‘Q’, Leaflet 1A, dated February, 1944.
42. Gun loading platforms were used during the trials. With two armourers employed, the times taken on two re-arming tests were 14 minutes and 12 minutes respectively.
Cine Camera Installation
43. The cine gun is situated in the leading edge of the starboard mainplane inboard of the cannon. From films taken with the guns firing, it was possible to trace some slight vibration, but not sufficient to warrant any change on the location of the cine gun.
TACTICAL COMPARISON WITH TEMPEST V
Radius of Action
44. From consumption tests carried out at this Establishment and from figures obtained from Messrs. Hawker Aircraft, it would appear that the radius of action of the two aircraft is approximately the same. Further tests on consumption are however necessary
(See Table at Appendix "C").
45. The Tempest II is 15 m.p.h. faster up to 20,000 ft., dropping to 10 m.p.h. from 4,000 – 7,000 ft., it then increases its advantage to 20 m.p.h. at 12,000 ft., dropping again to 10 m.p.h. at 15,000 ft. and holding this advantage up to its ceiling.
Acceleration in straight and level flight
46. The Tempest II is definitely superior when opened up from cruising or slow speeds to full throttle, and rapidly goes away from the Tempest V.
47. The Tempest II has a better rate of climb at all heights than the Tempest V, being 350 ft/min. better up to 3,000 ft., increasing to 1,000 ft/min. from 7,500 to 8,500 feet, dropping to 400 ft/min. at 12,500 ft. and maintaining this advantage service ceiling.
48. In the zoom climb at equal power settings, the two aircraft are very similar, but at full throttle the extra power of the Centaurus V gives the Tempest II a definite advantage.
49. The two aircraft are identical.
50. There is very little to choose between the two aircraft, if anything the Tempest V appears to have a slight advantage.
Rates of Roll
51. During the trials carried out, the Tempest II proved definitely superior to the Tempest V at speeds up to 500 m.p.h. I.A.S. As the two aircraft have the same airframe there appears to be no aerodynamic reason for why the Tempest II should be better. It is therefore assumed that the ailerons on Tempest II MW.754 are above the average, and may not be truly representative of a production aircraft.
52. The Tempest II is superior to the Tempest V in every way, except in the turn where it is at a slight disadvantage.
TACTICAL COMPARISON WITH THUNDERBOLT II
53. Although the Thunderbolt tested was not fitted with water injection, the figures quoted under "Speeds" are based on the maximum power so developed, i.e. 58” of mercury as against the normal 52”.
54. The Thunderbolt has a greater radius of action at all engine settings and at all heights (See Table at Appendix "C")
55. The Tempest II is some 80 m.p.h. faster up to 2,000 feet, dropping to 60 m.p.h. at 7,000 feet, then increasing to 70 m.p.h. at 12,000 feet. After this it drops rapidly to 40 m.p.h. faster at 20,000 feet, and the two aircraft are the same at 28,000 feet. Above this height the Tempest falls off progressively, becoming 20 m.p.h. slower at 31,000 feet.
Acceleration in straight and level flight
56. The Tempest has an advantage at all heights. Even at high altitude where the Thunderbolt is faster, the Tempest pulls away initially.
57. The Tempest II is better by 2,000 ft/min. at ground level, decreasing to 1500 ft/min. at 8,000 ft., then decreasing rapidly until parity is reached at 21,000 ft. Above this height the Tempest falls of progressively, being 500 ft/min. slower at 28,000 ft.
58. At low altitudes and equal power the Thunderbolt has a slight advantage, but at full power and at high altitudes the Tempest has a definite advantage.
59. The Tempest II always out-dives the Thunderbolt, the advantage being more marked at full throttle.
60. The Tempest II can always out-turn the Thunderbolt, the advantage being more marked to the left.
Rate of Roll
61. At speeds up to 300 I.A.S. there is little to choose between the two, the Tempest having a slight advantage to the right and the Thunderbolt to the left. Above 300 I.A.S. the Tempest become increasingly superior.
62. It is difficult to make a clear-cut comparison between the performance of these two aircraft, as the Tempest is a comparatively low altitude fighter and the Thunderbolt was designed as a high altitude aircraft. The Tempest is superior at altitudes below 21,000 feet, except in range and endurance. Above this height the Thunderbolt comes into its own, and is increasingly better with altitude.
SUMMARY OF CONCLUSIONS
63. The Tempest II possesses very high performance at low or medium altitudes and is therefore eminently suitable for ground attack or for air combat at those altitudes.
64. Its radius of action is approximately the same as that of the Tempest V but considerably inferior to that of the Thunderbolt II. The tactical value of the aircraft would be enhanced if a long range tank could be carried as well as bombs or R.P.: the provision of an extra 90 gallons fuel tank would increase the radius of action by 175 miles at fast cruising or 250 at economical cruising speed.
(See Appendix "C").
65. The Tempest II is easy to fly and handles pleasantly in all manoeuvres. Its very high speed has been achieved with moderate wing loading and a high degree of manoeuvrability has therefore been retained. This aircraft, however, can never be equal in this respect to the current "Ju Jitsu" Japanese fighter which has sacrificed speed and armour for exaggerated manoeuvrability.
66. The fire power of the Tempest II is formidable, especially with the increased rate of fire available from the Mark V 20 m.m. gun. Although the duration of fire is similar to other contemporary British fighters, it is for consideration whether it will be entirely adequate to meet all possible operational contingencies in S.E.A.C.
67. One bomb hook is incorporated under each wing but none under the fuselage. Provision is made for the carriage of R.P. on Mark III or Mark VIII installations. The fitting of a bomb hook under the fuselage would also represent a valuable addition to the potential striking power of this aircraft. (Para. 64).
68. In comparison with other British contemporary fighters the aiming qualities of Tempest II are good. Like all single-engine aircraft without contra-rotating propellers it is sensitive to changes in speed which involve continual rudder trimming or application of heavy foot loads to prevent skid. This is a major source of inaccuracy in ground attack.
69. The aircraft is considered a good sighting platform but it is not yet known what effect the engine vibration may have on the Gyro Gun Sight installation.
70. Mechanically, the engine has been found most reliable. Pilots, however, may at first feel concern about the vibration which occurs at certain engine settings although this has not been found to affect engine reliability.
71. The need for attention to cylinder temperatures between the economical cruising boost and the rated boost gates is a disadvantage, especially to pilots searching or flying in formation.
72. For ground attack, the advantages of comparative invulnerability and the protection offered to the pilot by the air cooled radial engine need no stressing. The armour protection is satisfactory for air combat. No provision has been made for ground attack.
73. The Tempest II possesses an ample margin of performance over any known current Japanese fighter and the fitting therefore of R.P. and bomb installations should not materially prejudice the aircraft’s superiority in air combat.
74. Like the Thunderbolt, the Tempest II was designed for air combat but is now likely to be employed mainly for ground attack in S.E.A.C. It is recommended therefore that the following equipment should be added to adapt it for its new role:-
|(i) ||An additional bomb hook under the fuselage to carry either a 1,000 lb. bomb or a drop tank of approximately 90 gallons capacity. (See Paras. 64 & 67.).
|(ii) ||Armour, to protect the pilot at vulnerable parts of the engine against fire from the ground (See Para. 72).
WWII Aircraft Performance
Tempest V Performance
75. Urgent steps should be taken to develop a fully automatic carburetor control which will maintain correct mixture between economical cruising boost gates without distracting the pilot’s attention. (See Para. 71).
76. To enhance aiming qualities, the aircraft should be considered for fitting with a contra-rotating propeller (See Para. 68).
77. With the same object in view the instrument panel should be fitted with a rudder trim indicator on the lines of the elevator trim indicator in the Spitfire. This instrument will allow the pilot to preselect his rudder trim with reasonable accuracy before going into a dive. (See Para. 68).