Testing for combat

The famous English testpilot Eric Brown flew 487 different aircrafts (all versions of the Spitfire he flew counts as one aircraft!!). In his book "Testing for Combat" he remembers his flying and experience with, among others, the Tempest Mk. V.

 

Hawker Tempest V

 

 

"After the shaky start of the Typhoon it must have seemed improbable that there would be a Typhoon II, but this in fact was the designation of the design tendered by the Hawker company to meet Air Ministry Specification F.10/41, and which eventually became the Tempest.
Like the Typhoon, the basic design of the Tempest catered the alternative powerplants, and in this case three different engines were considered - the Napier Sabre, the Bristol Centaurus radial, and the Rolls-Royce Griffon. The first prototype to fly, on 2nd September 1942, was the Tempest V powered by a Sabre IIA of 2,180 hp.
The Tempest distinguishable from the Typhoon by its elliptical, thin-section wing, which necessitated the reduction of the amount of fuel carried in the wings. Consequently an extra fuel bay was inserted in the fuselage behind the engine, and this lengthening of the fuselage forward called for increased fin area aft. The end result was a sleek, powerful looking aeroplane of considerable aesthetic beauty.

The first production Tempest V flew on 21st June 1943, and the first machines entered operational service in April 1944. This turned out to be most timely, because the German V.1 flying-bomb offensive was launched in June 1944. The V.1 could attain a normal operational speed of 400 mph at heights usually between 1,000 and 2,500 ft. This severely taxed the interception capabilites of British fighters, and some bombs were getting through to London and beyond. I can vouch for this as my first home in Aldershot was completely demolished when a V.1 impacted in the garden, seriously injuring our charlady, injuring my wife and killing our dog.

About mid-June a crash programme was initated to improve the low-level performance of the Spitfire, Tempest V, and Mustang III by using a specially developed 150 octane aromatic fuel to give abnormally high power for strictly short bursts. The engine attrition rate would of course be high, but the urgency of the situation demanded drastic measures.
I was very involved in these exhilarating trials requiring high speed runs at ground level, during which the Spitfire XIV with its Griffon boosted to +19 lb reached 365 mph, the Tempest V with its Sabre boosted to +10 1/2 lb hit 405 mph, and the Mustang with its Merlin boosted to +25 lb actually attained 420 mph.
During these trials I was flying Tempest V JN735 on 26th July at just after 7 o´clock in the evening, and had completed a 5 min level run at 1,000 ft at +9 lb boost, 3,650 rpm, which the airscrew pitch lever fully forward. I then climbed through cloud to 6,000 ft, where the second run was made under similar conditions, for it was known that the V.1 could fly up to almost 10,000 ft.


The third run was made at 7,000 ft, at which height only +8 1/2 lb boost was obtainable at full throttle, and after 3 1/2 min I detected a slight smell of burning coming from the floor of the cockpit. A quick check of the negine instruments showed zero oil pressure and oil temperature, with the coolant temperature 108 C. Since the engine had never faltered I suspected oil gauge failures, but throttled back to -4 lb boost and 2,900 rpm and asked for an emergency homing on the R/T, which I was given. I flew on this course at the same height and low engine settings as before until I thought I was near base, when I decided to descend through the solid cloud (top 5,800 ft and base 2,300 ft). On entering the darkness of the cloud I could see the whole top engine cowling glowing hot between the two sets of exhausts, although this had been unapparent to me in the bright sunshine. However, the engine was still running, so I continued the descent, but before I broke cloud the engine began to misfire badly and the propeller started to overspeed. I immediately pulled the constant-speed lever back to the fully coarse stop, but the revs. reached 4,200 and then there was a loud bang in the engine, followed by a spray of oil which covered the windscreen.

In order to see out I had to undo my safety harness and peer round the opaque windscreen. The propeller had seized solid, and the fire under the cowling had now burst into intense white flames which were also creeping into the cockpit through the floor near the rudder pedals, so the underside must have been well alight too, a fact which was later confirmed by ground witnesses. The heat round my feet hastened my decision to abandon the aircraft. 
I removed my helmet and trimmed the aircraft for level flight at 1,600 ft and 170 mph, then stood up on the seat and put my left leg over the port side of the cockpit before reaching inside to pull the stick hard over towards me, so that when the aircraft reached an angle of bank of about 60 degress I could kick myself free. The altimeter had read 1,200 ft when I glanced at it as I grabbed the control column spadegrip.

When I pulled the parachute ripcord I could see I was heading for open fields, but I was hardly ready for the touchdown because I was watching the Tempest, which hit the ground and exploded some 200 yards from a small pond into which I found myself deposited. From this point the drama gave away to sheer comedy. 
The pond that received my unexpected visit was shallow and not particularly salubrious, so I moved as smartly as I could to its edge, only to find myself face to face with the only other occupant of the field - a very large unfriendly looking black bull. As I moved a few steps nearer it lowered its head and snorted through its ringed nose. Discretion being the better part of valour, I did a smart about turn and headed for the opposite side of the pond, but I had just got there when I realised that I had bbeb beaten to it by my bovine acquaintance, who was determined to provide a personal reception service. There was nothing for it but to await deliverance in some form or another. 
Alerted by the exploding aircraft, the local fire brigade and police soon arrived, but baulked at the sight of the bull. There was then a hiatus while the police found the owner, who appeared with a short rope which he passed through the animal´s nose ring and then gently led him off like a poodle. I may be wrong, but I could swear that the bull winked at me as he departed.

Although Britain´s first operational jet fighter, the Gloster Meteor I, was pressed into service to combat the "doodlebug menace", it was outflown at low level by the Tempest V, which accounted for 638 flying bombs out of the RAF´s total score of 1,771 destroyed during the period 13th June to 5th September 1944. 
Our other great interest in the Tempest V at the RAE was in its high Mach number characteristics, and these proved to be very similar to those of the Typhoon, except that it had limiting Mach number of 0.81 true and a critical Mach number of 0.83 true. At the latter speed the nose-down trim change was very strong, and a full-blooded pull was required to keep the dive angle constant until the altitude had fallen to about 15,000 ft, when recovery could be affected.
In our transonic research at the RAE we often exceeded the so-called critical Mach number, which was the limit advised to the Services as being that beyond which there was a grave risk of loss of control of the aircraft. In our case this was not a foolhardy venture, but a controlled step-by-step investigation into a region of risk, each step being analysed from the records obtained from special instruments carried in the aircraft. We were of course in a war situation and could not afford to take an excessive amount of time, so some of the steps were larger than would be made in peacetime, and this could increase the risk element
On 5th September 1944 I was carrying out a series of tests for the Aerodynamics Department in a Tempest V to measure the effect of drag at high speed by diving the aircraft through a timed altitude range of 2,000 ft, commencing at 7,000 ft and descending to 5,000 ft at steady speeds ranging from 390 mph to 525 mph indicated airspeed (IAS).


The last dive was started at 25,000 ft from a full-throttle level run, then bunting into a fairly shallow dive to 22,000 ft where MS gear was engaged, the throttle set full open, the airscrew pitch adjusted to fully fine to give 3,700 rpm, the elevator trimmed nosedown, and the rudder trimmed to starboard in a position gauged from the previous dive to 470 mph.
At 12,000 ft I experienced slight buffeting at 515 mph IAS, and at 11,000 ft found myself rapidly overshooting the desired IAS at 525 mph. I began to ease back on the stick, but it was frozen solid, and even a strong two-handed pull had no effect. In fact I had a runaway situation on my hands, and the IAS kept on building up to a peak of 560 mph IAS at 9,000 ft, and maintained this speed to 5,000 ft. During this peak period the boost reached +9 lb/sq.in, but I dared not remove either of my hands from the stick to touch the throttle as the starboard wing was now drooping, presumably because the aircraft was out of trim on the rudder, and I had to make a really tough physical effort to keep the stick central laterally whilst maintaining maximum backward pressure all the time. It is truly surprising the strength you find when survival is a stake. To add to the critical atmosphere, the buffeting had become acute and seemed especially bad forward of the cockpit.
On passing through 5,000 ft the elevator started to bite and I could feel the nose rising almost imperceptibly at first, then more positively until it passed through the level flight position at about 1,500 ft. I have to admit to a feeling of considerable relief
Examination of the aircraft after landing showed signs of strain in the region of the engine cowling. As this Tempest was fitted with a leading-edge pitot, the Aerodynamics Department calculated the true Mach number attained to be 0.87, which was the highest ever recorded on a Tempest. We certainly had not intended to go that far, but the best laid plans of mice and men...

The Tempest V was a great aircraft to fly, having the main assets of a fighter with excellent harmony of control, a good rate of roll, and being stable directionally and laterally but slightly unstable longitudinally. However, it had a very sharp stall without any warning whatsoever, and it was deficient in high-altitude performance. For landing, the aileron control was sluggish, and was the elevator control once the flaps and undercarriage were lowered, and the trim speed in the powered approach configuration was to high. Not a perfect aeroplane perhaps, but certainly a very good one indeed."

 

Source:
A big thanks to The Hawker Tempest Page´s biggest
fan in Norway: Øyvind Meisfjord