|
|
| Aircraft Type |
Vampire FB 5 & 9 |
Vampire T.11 |
| Engine |
de Havilland Goblin Mark 2 |
de Havilland Goblin Mark 3 |
| Maximum Thrust |
1,406 Kp 3,100 lb |
1,451 Kp 3,200 lb |
| Internal Fuel |
1,500 ltrs 330 Imp Gal 2,540 lbs |
1,500 ltrs 330 Imp Gal 2,540 lbs |
| Clean Take-off Weight |
4,790 kg 10,560 lb |
5,060 kg 11,150 lb |
Max Speed
(at 12,200m/40,000ft) |
882 km/hr 476 knots 548 mph |
839 km/hr 477 knots 549 mph |
Rate of Climb
(at 13,410m/44,000ft) |
2.54 m/sec 500 ft/min |
2.54 m/sec 500 ft/min |
| Service Ceiling |
13,410 m 44,000 ft |
13,410 m 44,000 ft |
| Time to 12,200 m/40,000 ft |
16.3 min |
20.0 min |
| Take-off Run to 15 m/50 ft |
832 m 2,730 ft |
832 m 2,730 ft |
ARTICLE ON THE HISTORY OF THE VAMPIRE BY MIKE FEENEY
A very early Vampire. This fine photograph of a very early Vampire shows the original fin/rudder shape and the high-set tailplane with its two anti-flutter mass-balance weights. Note also the design of the air intake to clear the flow from the fuselage boundary layer. From the size of the pilot's head and the narrow front screen, the small width of the upper cockpit may be judged. |
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The prototype Vampire was the DH.99 which first flew on September 20th, 1943 in the hands of Geoffrey de Havilland Jnr (who was killed in September 1946 when the second prototype tailless DH.108 broke up at Mach 0.8. This was a Vampire fuselage to which a 45° swept wing had been attached). But unlike the Meteor, which was intended for squadron service from the outset, the DH.99 was an experimental project with the objective of determining whether a single-engine turbojet type could attain sufficient performance to prove useful. It used Frank Halford's H-1, the UK's first production jet. Halford was then a consultant but soon joined the de Havilland Engine Company as its Chairman. DH produced the H-1 which became the Goblin.
Following successful trials with the DH.99, the Air Ministry ordered, under Spec. E.6/41, three prototypes which was designated as the DH.100 and thankfully named the Vampire instead of the proposed "Spider Crab". It was a simple structure comprised of the mainplanes with the tail-booms bolted to the wing spars. The cockpit and nose section was created from moulded birch and balsa ply-wood in the same manner as was the DH Mosquito. DH took a gamble in using a twin tail-boom layout as aeroelastic rigidity and flutter problems could have occurred; when compared to a rigid single fuselage design. But with a single-engine type, they considered it essential to optimise the thrust output by eliminating a long tail-pipe or a bifurcated exhaust system.
The flight controls were simple cable-operated with no power-boosting. The cockpit was pressurised to a differential of 2.2 psi. The undercarriage was hydraulically operated with a castoring nose-wheel. Brakes were the typical DH pneumatic style, fed by a pre-charged accumulator and using a single control column actuator and rudder application for asymmetric braking. Split flaps were used and a speed-brake was installed on the top of each wing. The early models had squarish fins with the tailplane mounted high. This was soon changed to the more triangular shape with the tailplane set lower.
Initially, some problems were encountered with over-sensitive ailerons and some yaw instability and the stall was somewhat abrupt. But the general opinion was that it was a particularly pleasant aircraft to handle up to about Mach 0.75 to 0.78 when uncommanded roll and pitch changes would occur; nose-down pitch becoming quite severe above Mach 0.8.
Before the advent of underwing drop-tanks on the early fighter models and then a new wing on the FB.5, which had hard-points for bombs and drop-tanks, the Vampire's endurance was limited to about 45 minutes in the interceptor role. To understand why, we need to know something of Frank Halford's H.1 "Goblin". In RAF service the name led to ribald comments as there was a popular vacuum cleaner that went by the same name; a Goblin Ace.
The de Havilland Goblin turbojet:
A Whittle Turbojet. This is the original Whittle W1X which powered the Gloster/Whittle G.40/E28/39. At that time it produced only 860 lbs static thrust which resulted in a less than sparkling climb rate of 1,060 fpm and a max. level speed of 290 knots. This engine model was also sent to the USA to power the first American jet aircraft, the Bell XP-59 which needed two of them. The Whittle engine was developed into the G.E. J.31 of 2,000 lbs thrust. Even with two of these, the production P-59B Airacomet, with a max. level speed of only 360 knots, did not perform as well as the current reciprocating-engine fighters. But it did provide experience of operating turbojets. Looking at the motor we can see the tubes delivering compressed air to the combustion chambers/burners. It is obvious why they came to be called "cans".
A Schematic of Whittle W.1. This is a not very good image of a schematic diagram of the Whittle W.1. If you follow the flow arrows you will begin to understand just what a convoluted journey the air and combustion gases had to follow before exiting out the rear end. Air enters into the compressor casing and is then turned into the tubes which feed it to the annular cans. However, inside each exterior can is another tube-like part which is the actual combustion chamber within which your actual fire is lit. The incoming compressed air is largely conveyed between the outer and inner tubes and then reversed where the igniters are fitted. But not all of it, as the inner combustion chamber has many holes drilled into it which permits air to also enter at points along its length. This air helps cool the inner walls of the cylinder.
So one can now understand one of the reasons why Frank Halford decided to straighten out Sir Frank's masterful design and create the (more or less) straight-through Goblin.
Halford began designing the H.1 in 1941 and it first ran in April 1942. It was essentially a straightened-out Whittle reverse-flow engine in which the airflow and hot gases flowed along a most convoluted path before blasting through the turbine blades. But in the H.1, a single-sided centrifugal compressor was used (very similar to a large piston engine's supercharger) to supply the 16 combustion chambers and to cool the motor. The hot gas then drove a single row of turbine blades which drove the compressor. Whilst longer than Whittle's layout, it was tidier, easier to produce and maintain and more efficient. The first H.1s produced only 2,300 lbs of static thrust but the production Goblin I was rated at 2,700 lbs with an overall pressure ratio of 3.3:1. This was steadily increased to, in later Goblins, to 3,100 (Mk.2), 3,350 (Mk.3), and 3,750 (Mk.4).
A Goblin II Cutaway. This is a magnificently cut-away example of a Goblin II. It clearly shows the large centrifugal impeller/compressor which is obviously derived from a piston engine supercharger. The turbine rotor is also clear with its large number of small blades. I estimate about 80. It should be remembered that the early designers of gas-turbine engines had much proven turbine-blade knowledge to refer to; such as the Parsons high-pressure steam turbines which had been in wide use since the 1800s. The pioneers big problems involved finding metal alloys which could tolerate high temperatures, at high rpm, without undergoing excessive "creep" and shaping the combustion cans so that the airflow through them shielded the metal walls from direct flame impingement which would cause hot-spots and failure with dire results to the adjacent airframe (only a small percentage of the airflow is required for combustion). The schematic drawing of a Whittle W.1 below should assist in understanding the combustion chamber design. The other exterior components are items such as the High Pressure fuel pump, Fuel Control Unit, the high ampere igniter unit, electrical generator and starter motor or cartridge starter unit. The unit on top with the cooling fins is a Roots blower for the cockpit pressuration. It is comprised of two rotating inter-meshing rotors which simply "displace" air from one side of the displacement pump to the other. The pressure increase is due to the downstream plumbing; the resistance to flow. I recall these well as one of them was fitted to three of the R.R. Dart engines on the Vickers Viscount to supply the pressurisation system. They were controlled by "Spill valves". One spill was closed for initial climb, the second at 5,000 feet and the third at 15,000 feet.
Apart from its horrific fuel consumption of, at maximum thrust, 465 Imperial gallons per hour, the Goblin suffered from another trait which needed very aware pilot handling. The power output of a reciprocating engine is controlled by mass airflow through the carburettor by the throttle butterfly. The carburettor responds to the intake flow and pressure by supplying an appropriate fuel-flow. However, with a turbojet, the reverse is true. The pilot, by way of the Fuel Control Unit (FCU) selects the amount of fuel which is sprayed, at very high pressure, into the combustion 'cans'. This increases the hot gas flow which increases the turbine and compressor rpm. But there is a time lag before the compressor can deliver enough air to match the higher fuel-flow. Later FCUs incorporated a device to limit the pilot's demand for fuel so as to prevent a grossly over-rich situation occurring which could result in a flame-out. The Goblin had no such system with the pilot's throttle acting as a simple 'tap'. So, particularly on approach, the Vampire pilot had to try and anticipate his thrust needs and feed the fuel in slowly whilst noting the rate of rpm increase. If a go-around was needed great care and patience was required to get the engine 'spooled-up' to full power. The Vampire did have a pilot-operated air-relight system.
It may surprise some readers to know that the Goblin's static thrust was about only half of that produced by aircraft such as the 2,000 bhp F4-U Corsair and P-47 Thunderbolt, but these types lost considerable thrust when they operated at high true airspeeds due, in part, to their propeller blades having to increase to very coarse settings to maintain a positive angle of attack and to control rpm. Conversely, the turbojet can, assisted by ram air effect, maintain or even increase its thrust to virtually any airspeed; a huge advantage for an interceptor despite the large fuel consumption.
For a first-generation turbojet, the Goblin performed well considering it was still somewhat of an experimental engine. Following are some basic specs. for the Goblin 2:
Compressor: Single centrifugal;
Combustion chambers: 16, radially mounted;
Turbine: Single stage;
Length: 107 inches (2.7 m);
Diameter: 50 inches (1.27 m);
Dry weight: 1,550 lbs (703 kg);
Maximum thrust: 3,100 lbs at 10,200 RPM;
Pressure ratio: 3.3:1;
Turbine inlet temperature: 790° C;
Thrust to weight ratio: 1.9 lb per lb;
Specific fuel consumption: 1.3 lb per lb thrust per hour;
Full thrust fuel consumption: 465 Imp. gallons per hour (2114 litres per hour). To put that into perspective, a 14 cylinder, 1,200 bhp Pratt & Whitney R-1830 producing, at take-off power, about 3,500 lbs of thrust, burns 100 Imp. gph and 35 gph on normal cruise. It certainly demonstrates just how thirsty it can become to feed a 16 can continuous combustion turbojet as compared with supplying 14 cylinders which are firing only on every fourth stroke.
Some thrust data for the Goblin II as fitted to the Vampire Mk.3.
DH stated that the dual intake ducting was about 95% efficient. My 1947 "Flight" reference states that at 10,000 feet, at 10,000 rpm and 300 mph (260 knots) the thrust is 1,900 lbs but at 8,000 rpm thrust is only 900 lbs. Above 400 knots TAS, ram effect begins to markedly increase the potential thrust available; subject to turbine temperature limitations of course.
Production:
A Cutaway of Vampire F.1. I must thank my chums at www.flightglobal.com for the use of this cutaway drawing. They are jolly good Brits and I have been contributing stuff, such as this article, onto their website for several years now. I can commend their ever-growing site to readers. For those who don't know it, it is the "E" site for the "Flight International" weekly journal.
Production of the F.1 began in 1946 and was contracted to the English Electric company due to de Havilland's high workload on other projects. Various models were also built in Australia, Canada, France, Italy and Switzerland. The main variants numbered 31 which includes the DH.113 radar-equipped night fighter, the cockpit of which was based on the Mosquito, the DH.115 trainer and the Sea Vampire which was a beefed-up development of the F.3 for carrier use. The Vampire served with at least 31 air forces. The Australians produced 80 single-seaters which were powered by the Rolls-Royce Nene which had a thrust of about 2,000 lbs more than the Goblin.
As it is quite impractical for me to detail all the variants, I shall focus on the significant fighter-bomber model; the FB.5 which sold in large numbers.
A Vampire FB.6 Gear Down. A photograph of a civil Swiss Vampire FB.6 (HB-RVN) which I like as it shows the underside and the gear extended. The FB.6 is virtually the same as were the RNZAF's FB.5s. It also provides a good view of the drop-tanks on their pylon mounts.
The total production of all Vampire variants was 3,269 built in English plants and a further 1,069 constructed abroad under licence.
The FB.5 fighter-bomber:
With the advent of the much improved Gloster Meteor Mk. 8 and the prospect of much more powerful second-generation interceptors, such as the Hawker Hunter, coming on line in the 1950s, de Havilland decided to develop the Vampire F.3 into a ground-attack aircraft. They slightly shortened the wings but strengthened them in order to fit hardpoints for external fuel tanks and/or 500 or 1,000 bombs. Rocket racks were installed between the tailbooms and fuselage to take 7.62 cm rockets. A longer stroke main undercarriage was fitted to increase the ground clearance for underwing loads and to cope with the increased take-off weight. An ejection seat was considered but was rejected due space and weight factors. This decision did not please the pilot fraternity who may have had to operate at low level into fire from the ground. The RAF did operate the FB.5 in war zones in the Middle and Far East. This variant first flew in June 1948 and was built by English Electric through to 1951. The RAF used 930 and 88 were exported.
From 1951 the FB.5 began to replace the RNZAF's DH Mosquitos and P-51D Mustangs in the strike role. It was a major change for the pilots as, whilst the Vampire was faster than the piston-engined types, its endurance was vastly less than the long-ranging Mustang and Mosquito. The pilots had to modify their thinking from many hours of fuel to just minutes.
Let's now consider the basic specs. of the FB.5:
Powerplant(s): The great majority of RNZAF FB.5s used the 3,100 lb static thrust Goblin 2 with some fitted with the Goblin 3 of 3,350 lbs static thrust;
Wingspan and area: 38 feet. 262 square feet;
Length: 30 feet 9 inches;
Empty weight: 7,250 lbs (3,290 kg). This of course could vary;
Maximum take-off weight: 12,390 lbs (5,620 kg);
Maximum wing loading: 47 lbs/square foot;
Take-off distance to 50 feet at 10,500 lbs: 3,600 feet at sea level, nil wind and 15°C.
Landing distance from 50 feet: about 3,000 feet using moderate braking;
Rotate speed: 70-75 knots. Lift-off at 95-100 knots with initial climb commencing at 115-125 knots. There was some variation between pilots on these numbers with some preferring a higher rotate speed and more airspeed build-up before climbing.
Maximum true level airspeed: 460 knots. This figure is for a clean aircraft;
Stall speed at near max. weight, zero flap and idle power: 88 knots. With gear down and full flap 72 knots;
Approach and threshold speeds: 115 knots on short final was common; reducing to about 100 crossing the threshold. The RAF notes for the F.1 state a minimum of 87 knots.
Recommended entry airspeeds for aerobatics: Roll 260 knots, loop 380, climbing roll 400, Vne 455 knots. These are RAAF numbers for their RR Nene Mk.30s. Could be lower for the FB.5.
Service ceiling: 44,000 feet. again, this if for a clean aircraft;
Range: 1,045 nautical miles. This is with underwing tanks, at optimum cruise speed and altitude and with nil reserve;
Rates of climb (approx): At a best rate of climb IAS of 220 knots. Initial: 4,300 fpm; at 20,000 feet: 2,000 fpm; at 30,000 feet: 1,000 fpm, then reducing to a 'creep' climb of 100 fpm above 40,000 feet as fuel burns off. Climb IAS could vary between air forces with some using higher operational speeds. On their RR Nene-powered Mk.30s, the Aussies used 290 knots.
Typical cruise indicated and true airspeeds (IAS/TAS): Low level: 350 knots TAS. At 12,000 feet and 8,700 rpm 280 knots IAS (335 knotsTAS).
Due to the 'pure' turbojet's markedly losing centrifugal compressor efficiency when operated at less than near maximum continuous rpm, the IAS for optimum range is significantly faster, as related to stall speed, than for piston-engined types. In the Goblin Vampire's case, the best-range IAS at sea-level was about 290 knots. This reduced by a tad over 3.0 knots per thousand feet so at 30,000 feet the IAS would be in the vicinity of 200 knots with a resulting TAS of 330 knots using the ISA temperature lapse rate. So broadly speaking we can say that the Vampire's nautical miles per Imperial gallon at low level is 1.0 which progressively improves to about 3.0 at 35,000 feet.
Typical warload: 4 x 20mm Hispano cannon using a gyro gunsight, 2 x 500 or 1,000 lb bombs and 8 x 7.62mm rockets
The two-seater Vampires:
A Vampire T.11. Seen here during a landing roll-out is Brett Emeny's superb T.55, ZK-RVM, in the scheme of NZ5712. Brett's fine displays are a highlight at New Zealand air shows. Evident is the type's low stance and jet-pipe position which can cause heat damage to sealed surfaces if the engine is run for too long with the aircraft stationary. Clearly shown are the high-drag split flaps. The DH.115 trainers have a short outer tailplane extension to enhance pitch stability.
As the RAF began to phase out the Mosquito night-fighter (N.F.) and prior to Armstrong Whitworth's development of the Gloster Meteor F.8 into the 'stretched' two-seat night-fighter, DH decided to, initially as a private venture, construct a N.F. version of the Vampire Mk.5. Essentially, they used the cockpit and nose section of the N.F. Mosquito and merged it onto a Vampire. This became the DH.113 and was used by the RAF as an interim all-weather fighter until the A.W. Meteor N.F.11 became available. Some 95 DH.113s were produced; 66 N.F.10s and 29 N.F.29s. A number were exported, mainly to Italy and India.
The cockpit was very tight so the radar operator's seat was moved back somewhat. The Mk.10 radar was used. Performance was much the same as the single-seater but rate-of-climb was a little less and service ceiling was a few thousand feet lower.
The NF.10 became the basis for the DH.115 trainer version which, other than the removal of all the radar gear and installation of dual controls, was the DH.113 airframe.
This view of a DH.115 cockpit shows just what a 'cosy' fit it is for two average size chaps. There were height and leg length limits for Vampire pilots. The Brits were masters at cramming in a multitude of controls, switches and instruments into cockpits of limited dimensions and volume. Looking at this array, and apart from its performance, it is obvious why the DH.115 was classed as an Advanced Trainer. Imagine transitioning from a 150 knot RAF piston-engined fixed-undercarriage Percival Provost onto this complexity of systems. However, RNZAF pilots transitioned from the North American T-6 Texan/Harvard which, in some respects, was more of a handful than the Vampire.
Prior to and during WWII, it was standard practice to send pilots off on advanced aircraft such as the Spitfire, Tempest, Mustang, P-47 Thunderbolt etc with no dual air instruction on the type. The new fighter pilot would undergo training in an advanced trainer such as a Harvard or Miles Master, study the pilot's notes, sit in the cockpit to become familiar with the systems, receive a briefing from an instructor and go and fly the aeroplane. It sort of worked though the 'ding' rate was far higher than would be tolerated in peace-time.
So after WWII, many air forces changed policy and we began to see two-seat versions of many types of jet aircraft and then dedicated jet and turbo-prop training types. But a major advantage of the trainers was that they greatly enhanced role training. "Talk and chalk" is important but there is nothing like getting in an aircraft and actually doing it under direct guidance and supervision. Whilst accidents can still occur due to both pilots becoming excessively cockpit task-focused and losing the 'big picture', that is an instructor problem.
The Sea Vampire and the remarkable Eric "Winkle" Brown CBE, DSC, AFC.
Whilst not of high quality, this photograph is particularly historic in that it shows the very first take-off by a turbojet aircraft from an aircraft carrier. The ship was HMS Ocean and the modified Vampire had carried out the first jet landing on a carrier. The trials were flown by test pilot Captain Eric Brown as described in the text above. Using the full length of the deck and greatly assisted by the ship's speed and, presumably, some wind, the aircraft was airborne well before reaching the bow. The American's first carrier fighter, the twin-engined McDonnell FH Phantom, had flown in January, 1945 but did not fly onto, and take off from, a carrier until its first trials on the USS Franklin D. Roosevelt in July, 1946.
On December 3rd, 1945, Royal Navy Captain Brown carried out the first landing and take-off by a jet aircraft on an aircraft carrier; HMS Ocean. The aircraft was a modified Vampire F.1. As a result the RN ordered a navalised version of the FB.5, 18 of which were delivered during 1948/49. The Sea Vampire, at max. weight, had marginal take-off performance unless their was a decent wind blowing to add to the carrier's speed. It was mainly used in a training role and did not become truly operational as a ship-borne interceptor.
Eric Brown flew operationally, and then as a test pilot, throughout WWII and for many years afterwards. He is believed to have flown more aircraft types than anyone else in history. These include many WWII German and Japanese types. He has written extensively on his experiences. I recently watched him being interviewed on a TV history program and his memory was most sharp and lucid. I have an Email contact in the UK who knows Eric so I am hoping that he might give this fine old gentleman a copy of my Vampire essays. I urge you to Google Eric's full name and read the excellent Wiki entry you will find.
The Vampire and MiG-15.
As the RAF Vampire interceptor models were deployed to Germany to defend the NATO nations against USSR aircraft, it is interesting to reflect on how they might have fared against the MiG-15 which entered service in late 1949. The MiG-15 was powered by a Rolls-Royce Nene of 6,000 lbs static thrust at sea level. Amazingly, the British Govt. permitted the Nene to be built under licence as the Klimov VK-1 (the story has it that the Soviets never paid the Brits a penny in licence fees).
The MiG-15 proved to be much superior than all the contemporary straight-winged single-engined jets such as the Republic F-84, Lockheed F-80, Grumman F9F Panther, Supermarine Attacker, Hawker Seahawk and the Vampire. Of similar weight and size to the Vampire, its initial climb rate was, at 10,000 fpm, 2.5 times greater and its service ceiling of 50,000 feet was way above the Vampire. With its wing-sweep of 35°, the MiG's maximum level TAS was 580 knots with its limiting Mach number being just under M 1.0.
The rugged little MiG came as real shock to the Western nations and it was produced in staggering numbers; possibly as many as 18,000. Until the advent of types such as the F-86 Sabre and Hawker Hunter, there was nothing that could touch it. But my point is that the Vampire, as an interceptor, became obsolete, at least in Europe, almost as soon as it entered service in substantial numbers.
Flying the RNZAF's FB.5. Recounted to us by retired RNZAF Air Commodore Stewart Boys.
Flying the Vampire FB5 was a delight. The visibility was fantastic and the controls were light and well balanced. Certainly, the Goblin first-generation jet engine required some careful throttle handling, and monitoring of maximum rpm and jet-pipe temperature but that was easy to get used to. Given that and the high servicing standards of the RNZAF, it was generally reliable.
For one used to tail-wheel piston-engine types, the FB5 was easy to handle on the ground, and the take-off and landing could normally be accomplished on a paved or firm grass runway within 3 - 4,000ft. There was no tendency to swing on take-off or landing, or any change in roll and yaw in the air, hence only one trim control was necessary - that provided for the elevator.
The FB5 was climbed at 250 knots IAS into 0.65 Mach. The times to climb from sea level were as follows: To 20,000ft 6.5 minutes; to 35,000ft 16 minutes. The limiting altitude was 42,000ft for aviation medical reasons. If cabin pressurization was lost above this altitude the pilot was liable to become hypoxic pretty quickly, even when breathing 100% oxygen. Climbing to 40,000ft or higher in the Vampire was operationally a rare event because of the time taken (about 25 minutes from sea level) and, when there, speed and manoeuvre were limited by the reduced air density. Most Day Fighter/Ground attack (DF/GA) high-level training was carried out at about 30,000ft and below.
Today, passengers in big jets routinely fly for hours up to a maximum of 45,000ft altitude while enjoying a cabin altitude of 8,000ft or less. No such comfort in the FB5. Cabin pressurization did not become effective until 15,000ft was reached and thereafter increased progressively such that at the maximum altitude of 42,000ft the cabin altitude was about 25,000ft. Hence, the effects of altitude were much more apparent in any flight to those sorts of levels in the Vampire, than they are now in a modern aircraft. It did not help if a pilot had some fillings in the teeth that were not properly sealed, as some sharp pain could be felt when any air trapped in the tooth expanded in the climb. This was nothing that a visit or two to the dentist couldnt fix, but the same could not be said for the discomfort felt if a pilot was foolish enough to fly with a heavy cold and suffer sinus or ear problems.
Fortunately the Vampire was fitted with a very good demand air-mix oxygen regulator which was turned on before take-off and automatically provided an increased supply of oxygen, becoming 100% at maximum altitude. Thus cases of even mild hypoxia were extremely rare. The cabin was otherwise kept at a reasonably comfortable temperature but one had to be careful to use the separate demisting control properly to prevent fogging of the windscreen and canopy particularly after there had been a rapid descent from a 'cold soak' at altitude.
The FB5 had no ejection seat, but we did have survival equipment - a 'Mae West' life jacket was worn for every flight, and we strapped first into a parachute and dinghy with some rations and a fresh water cushion that nested in the seat, before strapping into the seat itself. Bailing out of a stricken aircraft could be difficult. The only instruction given in the Pilot's Notes was the same as that given to Spitfire pilots - jettison the canopy, wind the trim hard forward, release the seat straps and roll upside down.... In out-of-control situations, this would not be possible and getting clear of the aircraft with all of that gear strapped to the bum was going to be a challenge. If you made it, then at high altitude you had to pull the little toggle that gave you the oxygen stored in the seat pack and free-fall before pulling the rip-cord for the parachute at a lower level. If you then landed in water, the dinghy was released from two side clips, recovered by pulling on a lanyard and inflated by pulling the handle on an attached bottle of gas. Pilots who were deterred from flying by dwelling too long on this sort of detail were few and far between.
The FB5 was limited to 435 knots at 10,000ft and above, or 0.78 Mach above 15,000ft. In a relatively shallow dive of 15 - 20 degrees with full power to maximum speed (called a 'Mach run'), compressibility effects could be felt as a progressive nose up change of trim starting somewhere between 0.71 and 0.76 Mach and then, as Mach 0.78 was approached, usually a very sudden nose-down pitch would occur, requiring a strong pull on the stick to control it. Sometimes an unpleasant porpoising movement would follow, and a wing drop and some buffeting were also likely. Recovery was achieved simply by deploying the airbrakes and closing the throttle.
All of the normal aerobatic looping and rolling manoeuvres or combinations could be flown with ease. The recommended speeds were: roll 240, loop 320, roll off the top 340, and vertical roll 340+. Inverted flying was limited to 10 seconds for reason of maintaining the fuel supply to the engine, and stall turns were forbidden because the engine was not built to run backwards should there be an inadvertent tail slide. Normal stalling was conventional and recovery simple. The power-off stalling speed at maximum landing weight was 90 knots (clean) and 80 knots with undercarriage and flaps down. Spin recovery was a different matter, and was considered problematic, particularly if recovery action was delayed. As a result, intentional spinning was prohibited.
The Vampire just loved to glide. A standard descent was with the throttle closed at about the speed which was used for the cruise, say 240 knots. From 30,000ft it would take 60 nautical miles (nm) and 11 minutes to reach sea level and required only 21 gallons of precious fuel. New Zealand approach controllers became very adept at being able to accommodate such a descent in controlled airspace as, in modern parlance, they knew the Vampire was "fuel challenged". If a flame-out occurred at altitude and relight attempts were unsuccessful, pilots were comforted by the knowledge that the Vampire would glide engine-out at 170-180 knots IAS at a rate of descent of about 1200 feet per minute. Depending on wind and other factors, this translated into about 2-3 nm per 1,000ft of altitude available. Hence a power-off forced landing could probably be made from, for example, 30,000ft to an airfield somewhere in the region of 60-90 nm distant. In fact, such an emergency IFR procedure was established and practised at some of the New Zealand airfields which were equipped with Cathode Ray Direction Finding (CRDF) initially and radar later.
The writer about to go flying a Vampire FB5 at Ohakea in early 1956. Note the usual kit for those days. A light cotton flight suit worn over normal underclothes, uniform khaki stockings and black street shoes. A leather helmet and goggles with an oxygen mask were worn and a short pig-tail lead for the radio was plugged in behind the head later. One of the two clips for the dinghy can be seen dangling from the left side of the Mae West, and hanging down in front at about belly button level is the T-shaped connector for the main and emergency oxygen supply. The clips etc, parachute and seat harnesses were connected up and tensioned once the pilot was seated.
The standard and most efficient rejoin to the circuit was by way of a "buzz and break" manoeuvre, normally restricted to not below 500ft AGL and 250 knots. The normal circuit height was 1,000ft AGL and the only real trick was to judge the "tip-in" point correctly for the conditions. Too far out and too late, and the approach tended to be dragged out and too flat. Too close in or too early, and it was very difficult to get the speed reduced to the proper approach speed of 130 knots at the start of final approach and reducing to 95 knots at the threshold even with the undercarriage and full flap extended. To provide for a better engine response (if needed) it was recommended that rpm should not be below 5500 until 'sure of making it'. Properly judged, a normal approach saw the throttle being closed at about 50-100ft AGL with a final short glide to the threshold. Landing was simple - a check of the rate of descent followed by an easing of the main wheels onto the runway.
Pure handling manoeuvres such as those described above, plus navigation, night and instrument flying, basic formation and low flying, took barely one month of the standard three-month operational conversion course on the Vampire. The remainder of the time was taken up with learning the basics of the DF/GA trade. This included such things as high and low level battle formation, first as a basic fighting element of a pair of aircraft, then as two pairs operated as a battle four. Practice radar intercepts and air combat manoeuvring followed and then came weapons training which was based on the exceptional (for that time) gyro gun sight (GGS).
The GGS was a reflecting gunsight developed by the British in World War II primarily to solve the problem of predicting where to aim the guns to get hits on a moving air-to-air target. It did this brilliantly, provided the pilot tracked the target with the central pipper (graticule) and continually informed the sight of its range by matching the surrounding ring of diamonds to its wingspan by using the twist grip on the throttle. Given these two things, the sight was able to predict the right amount of gravity drop and lead (aim-off) to give a reasonable assurance of scoring some hits.
This tracking and ranging might sound easy, but it took skill and practice to get it right. For example, any increase or decrease in the rate of turn when tracking would cause the gyro-controlled graticule to respectively lag behind or move ahead of the target, and similar effects occurred when the range from the target changed. So, practice tracking and ranging we did - initially without weapons mutually on one another using a GGS camera recorder to assess the results; then eventually with live 20mm weapons shooting at a banner towed by a Mustang in the early days and later by another Vampire. Usually, four aircraft would shoot against each banner tow with different-coloured paint-tipped rounds so that any hits could be credited to the right pilot when the banner was brought home. In case you are wondering, these shoots took place in a properly gazetted and notified air-to-air range out to sea from the Manawatu coast. Scores on these live shoots were respectable. As a student on the FOCU I managed 13% average hits on four solo air-to-air gunnery sorties. On my two other solo shoots, the banner was unfortunately shot away - not an uncommon event.
The GGS could also be adapted to give the right sight picture for air to ground gunnery, rocketry and dive bombing. The former was easy shooting at a 10 x 10ft target erected on the sand dunes at Raumai range on the coast out from Ohakea. A relatively shallow dive was employed but pilots still had to be careful not to become fixated by the target and end up flying through the ricochet area, or worse still, hitting the ground during recovery from the dive. Some very high air-to-ground gunnery scores were achieved, well over 20% hits on good days. But then, of course, nobody was shooting back!
In the early days, rocketing was based on a 35° dive angle and, with the GGS set to the correct R/P setting, the bottom diamond indicated the correct amount of gravity drop for the 3-inch rockets then carried. With appropriate allowance made for wind, some reasonable scores could also be obtained. Later, when the Canberras arrived, the Vampire trainers had to switch to using two-inch rockets. I recall that although these were of higher speed, they were not as reliable and average scores tended to suffer.
Dive bombing at 45° was carried out using "light series" bomb racks and eight 11.5lb practice bombs. These had been designed for use during the war from aircraft with a much lower speed than the Vampire. I always had the feeling that they were too light for the Vampire and did not represent the aerodynamics or ballistics of the real 500lb bombs. It was nevertheless possible to get average errors in the range of 20 - 40 yards for eight bombs dropped.
In the early days, at the end of the FOCU course, pilots became qualified for a posting to 14 Squadron during its deployments flying FB9 Vampires in Cyprus from 1952 - 1955 and in Singapore flying Venoms from 1955 - 1958: or alternatively to 75 Squadron which remained at Ohakea over this period with the original Vampire FB52s which were superseded over time by the FB5.
With the advent of the Canberra era in 1958, the Vampire unit in New Zealand became responsible for providing jet conversion and lead-in operational experience for those who were destined to fly the Canberras. Following the arrival in New Zealand of the Skyhawks in 1970 to replace the Canberras, the Vampires continued to be used for jet conversion and fighter lead-in training before pilots were posted after about one year to the Skyhawk Conversion Course. The Vampires were retired and replaced by the Strikemaster in this role in early 1973.
(Thanks to Mike Feeney) |
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