Flying the Vampire By: Des Barker
The second part of Des Barker’s feature on this, the first jet fighter type to be employed by the SAAF, gives a pilot’s viewpoint on what it is like to fly this aircraft. Part One was published in last month’s edition of World Airnews.
IN DISCUSSING the flying qualities of the Vampire, the first misconception that must be cleared up is that the dual seat T.55 was a similar aircraft to that of the single seat FB.9 – they might have had the same engine, wings, tail boom and name, but that was where the similarities ended. The T.55 had a relatively large nose which made it easy for pitch attitude control compared with the nose of the FB.9 which had no visible nose from the seated position.
Before your first flight in the solo, in an effort to demonstrate the landing attitude, technical personnel supported by an instructor, sat on the tail boom to lift the nose wheel to illustrate the change in pitch attitude for the landing. On rotation and liftoff there was not much ahead of the cockpit instrument coaming to assist in pitch attitude control which created a sensation of being in a glass bubble, but the human, having a great capability for compensation, soon adapted.
Pneumatic brakes were operated via a bicycle type hand brake situated behind the spade grip and required an adeptness at modulating the applied brake pressure while simultaneously using varying amounts of rudder pedal displacement.
Photo: Pieter Cronje
Although flying the Vampire was delightfully easy, taxiing the Vampire required the development of some fine hand and feet motor skills.
In addition, the low tailpipe clearance from the ground with the angled jet pipe, melted the tar if the aircraft was left idling; Vampire pilots were thus particularly sensitive to the hazard and would continuously be looking for cement rather than tar to linger on.
In those days, the Vampire was flown from paved or grass runways and pilots had to ensure that they did not stop over the grass which could catch alight from the hot exhaust gasses. AFS Zwartkop had cement holding areas at either side of the runway specifically to enable the Vampire to hold.
The rather basic split flaps, so typical of WWII fighters, were essentially for landing only and were not used for take-offs; their contribution to the lift coefficient in the first few degrees of travel provided was offset by the drag increase in the extended position, reducing the Cl/Cd significantly. Take-off at maximum thrust of 1 050 rpm, saw rotation at 85 KIAS with lift off at 115 KIAS as a function of aircraft weight.
When flying with under-wing drop tanks, it was essential to get the undercarriage up by 130 KIAS or the negative suction pressures around the drop tanks would prevent the undercarriage from retracting.
For those transitioning from Harvards or Spitfires, the first few flights were unusual in that there was no tendency to swing on take-off or landing and no torque or precession effects from the propeller to cater for – life had just become easier.By today’s standards, the climb speeds of 250 KIAS/M0,6 were rather sluggish compared with current interceptor specific excess energy profiles, but at sea-level, rates of climb approaching 4 500 ft/min were achievable. Time to climb from sea-level to 20 000 ft was typically 6,5 minutes increasing to 16 minutes to 35 000 ft., but because of the exponential decrease in thrust with increase in altitude, it could take about 25 minutes to climb to 42 000 ft pressure altitude.
The second generation Goblin, as could be expected, dropped off thrust to just 1 900 lbs at 10 000 ft at 10 000 rpm due to the centrifugal compressor efficiency drop off when operated at less than near maximum rpm.
Flight at altitudes above 35 000 ft were usually limited because of the exponential thrust decay, compressibility and the reduced manoeuvring capability; most operations were therefore conducted below 30 000 ft pressure altitude.The Vampire was pleasant to fly, but would bite hard if mishandled. There was no significant stall warning and pulling into an accelerated stall or snatching the pitch control at high angle of attack, could easily lead to a flick roll, either right or left which, if left unchecked, very rapidly departed into a spin. If the angle of attack was not decreased immediately, the “Vamp” would depart and spin.
Most probably one of the most important traps taught to new Vampire pilots was not to pull the aircraft into the stall during a hammerhead on to finals; rather go around. The clique “A PF pilot never goes around” could have been a contributory cause to the Vampire crash on finals to runway 19 at AFS Waterkloof in the late 1960s when the pilot apparently hammer-headed during the base leg turn to finals and pulled the aircraft through to final approach when the aircraft flicked and spun in. Pilots were taught and gained experience in this undesirable characteristic.
Photo: Pieter Cronje
Throughout the development of the Vampire, the small fins of the Vampire had been criticised for poor spin recovery characteristics and a tendency to overbalance near full rudder applications at high angles of attack.
Also criticised was the restricted visibility from the T.Mk 11’s framed cockpit canopy lid with the concomitant poor emergency escape clearances with no ejection seat fitted. A moulded single piece canopy was eventually designed to improve visibility and field of view and improve the egress space.
The one thing the early generation jet engines were not, was fuel efficient. Pilots converting from the Spitfire or Harvard to the Vampire certainly required a new mindset and respect for fuel consumption and tactical planning for a mission.
It would not be unfair to say that the engine “guzzled fuel” at 465 galls/hour (2 114 litres per hour) at full power and with only 330 Imperial Gallons (1 485 litres) internally, sortie lengths on clean aircraft were typically 45 minutes. Range with two 100 gallon under-wing tanks at optimum cruise speed and altitude with nil reserves, was 1 045 nm.
The world of high speed aerodynamics in 1950 was in its infancy with many myths prevailing as to the “monster” hiding behind the shockwaves.
In this case, the Vampire provided an entry platform into understanding compressibility effects. The Mach run was flown by climbing to 30 000 ft pressure altitude and then at full power 10 750 rpm, entering a 50° dive from a wingover......................... For the FULL ARTICLE please subscribe to our digital edition.