The Hurricane was not a particular success as a night fighter, but it proved very suitable as a night intruder with squadron's like No 1 - where it was used with great effect by Flight Commander Karel Kuttelwascher and Squadron Leader James MacLachlan - and No 43, both of which were based at Tangmere at the time of conducting such operations.
As one of 43 Squadron's night intruder pilots Harry Lea puts it:
"The Hurricane IIC was a splendid aircraft for the job in hand. It had range with its two 45 gallon wing drop tanks, excellent armament with four 20 mm cannon, and it was a tough, solid aircraft that could withstand a great deal of punishment and still survive. This later point was proved at the Dieppe Raid when we suffered severely from ground fire and all but two aircraft returned, of which five sustained varying degrees of damage, one of these you would wonder how it managed to stay in the air".
There were three features which particularly distinguished the intruder Hurricanes from the ones flown by 1 and 43 Squadrons in the Battle of Britain: colour, armament and fuel.
COLOUR
Prior to being allocated to night intruder duties, night-flying Hurricanes tended to have a hybrid day and night colour scheme: upper and side surfaces in dark green and dark grey (day fighter) camouflage with lower surfaces including fuel tanks all black and no underwing roundels (night fighter). However, many intruder Hurricanes were painted matt black all over (except for the red spinner). It was appreciated that the matt finish on the aircraft could increase 'drag' and therefore reduce top speed, but the intruder - unlike the inceptor - did not depend on speed but on concealment.
In spite of the black colour scheme, the aircraft could still give itself away in the darkness because the exhaust manifolds used to glow red hot, so part of the maintenance routine was to apply very thick red lead paint to the manifolds. As 43 Squadron pilot Jack Torrance comments: "Even with the flame shields over the exhaust, I found the flickering blue flames strangely comforting over the water but, once over the French coast, one felt very conspicuous in the night sky". His squadron colleague Morrie Smith makes the same point: "I felt that everyone for miles around could see the exhaust stubs glowing in the night, but the anti-glare cowlings protected the pilot's night vision from this glow".
Godfrey Ball, another 43 intruder, remembers a disturbing occasion on the return from an operation:
"As I descended deeper into the cloud, I experienced a frightening phenomenon: the whole inside of the cockpit was lit up by a red glow. My immediate reaction was: 'Fire!' But there was no heat and all my instruments showed everything to be in order, so I ventured to look outside. My two exhaust manifolds were belching out the usual flame, made perhaps a trifle more red and less blue from being throttled back, and this source had illuminated the surrounding very dense cloud. It was an eerie sensation but, once I knew what it was all about, it ceased to trouble me".
ARMAMENT
The IIC was fitted with four 20 mm cannon, two in either wing, in place of the eight or twelve Browning machine guns on the earlier marks. These cannon were French Hispano-Suiza HS.404 guns. It was immediately obvious that a Hurricane was a IIC because its cannon protruded so far out of the leading edge of the wings - the overall length was of the guns was 8 ft 2.5 in - and the recoil springs stood out along the barrels. These protruding cannon had rubber covers like over-sized condoms, so that it was a simple matter for ground crew to see if a returning pilot had used his weapons.
On No 1 Squadron's intruder aircraft, the cannon's ammunition consisted of equal quantities of high explosive (HE) and ball (20mm or 0.787 in). The former exploded on impact to create a hole in the enemy aircraft and the latter was a solid steel missile designed to pierce the plating of the German planes. They alternated in the belt and, at a muzzle velocity of 2,880 feet per second, it did not take them long to reach their target.
Many think of the fighter aircraft of the Second World War as having a considerable volume of ammunition - certainly the movies give that impression. In fact, the available firing time of a Hurricane armed with cannon was even less than for one with machine guns, although of course there was much more power in the punch.
The IIC's carried a total of 364 rounds (91 per cannon) which - at an approximate rate of fire of 600-650 rounds per minute - was only long enough for about nine seconds of firing. So every second had to count and a typical burst would only be between one and three seconds.
Like all fighter armament, the IIC's cannon were aligned to focus at a point some way ahead of the aircraft. The original Hurricane had its machine guns aligned to converge at a point about 650 yards ahead, but later the distance was reduced to 400 yards. Finally, at the insistence of Squadron Leader P J H Halahan (the Commanding Officer of No 1 Squadron until May 1940), the alignment was further reduced to 250 yards.
Therefore successful night intruder pilots would position themselves behind the enemy, so as to escape observation, and a little above or below, so as to hit the fuselage, and the usual mode of attack would be to tuck in close and fire from a distance of 100-200 yards.
Use of cannon could be colourful. Godfrey ball of 43 Squadron recalls:
"When shooting up trains, the cannon shells would ricochet from both the engine strikes and from the permanent way (if you undershot when aiming at the guard's van) and looked remarkably like flak- blue, red, green and white. It almost seemed at times as if I were going to fly into my own bullets!".
FUEL
Intruder operations over the Continent required plenty of fuel and so Hurricanes on such operations were fitted with two 45 gallon drop tanks, one under each wing. This additional 90 gallons of fuel, added to the 66 gallons in the two main tanks carried in the wings and the 28 gallons in the reserve tank located between the engine and the cockpit, provided a total of 184 gallons and took the overall combat weight to 8,000 lbs. If necessary, these drop tanks could be jettisoned by pulling a lever on the starboard side of the cockpit (what American pilots on long range Mustangs would later call, in characteristically colourful language, "punching your babies").
43 Squadron intruder Harry Lea points out: "Before carrying out an attack, we used to jettison our long range tanks. This was because, even when empty or partially empty, they were lethal when struck by enemy fire". So invariably the pilot - having started and taken off in the normal way on the main tanks - would use the fuel in these additional tanks before switching to his main tanks, in case he had later to release the drop tanks.
Another of the 43 Squadron intruder pilots, Godfrey Ball, recalls a particular problem about flying a Hurricane with drop tanks:
"This extra 90 gallons just about doubled our endurance in flying time. I always aimed to use this extra fuel up first. As we had no gauges for these extra tanks, it was necessary to time how long they had been in use very carefully for, if they ran dry, one was likely to get an air lock in the fuel system which, while not being disastrous, was very frightening, especially at night.
The Hurricane was fitted with a 28 gallon gravity tank which, when turned on, got rid of air locks very quickly, and it was fitted mainly for this purpose as air locks could also be caused by draining the main wing tanks. I allowed for a consumption of 60 gallons per hour so, when they had been on for an hour and a half, I would operate on the normal tanks. When actually in an area of possible combat, I always used the wing tanks rather than the auxiliaries.
One night over France, I ran the long range tanks dry by mistake and got an awful fright. I was only at about 500 feet when the red fuel warning light came on like a huge beacon in the darkened cockpit and, at the same time, the engine faded out. I had turned the reserve tank on in less than a spilt second but, although the engine responded quite readily, it seemed to me that it would never come good. It was only then that I found out how long 'immediate' could be, for the good book said that under such circumstances turning the petrol **** on to 'gravity' would bring an immediate response!".
The price of having drop tanks was a certain loss of manoeuvrability. As 43 Squadron Jack Torrance notes: "The old Hurricane gave a feeling of great reliability and steadiness, although it was sluggish in the air with the drop tanks full".
Of course, the benefit of the drop tanks was increased range. The combined fuel volume of 184 gallons enabled an operation to last - at a normal average consumption rate of around 50-60 gallons an hour - about three to three and a half hours and to cover - at an optimum cruising speed of about 170 mph - a range of about 900 miles. Since up to half the intruder pilot's fuel could be used reaching and returning from the general target area, his maximum time over the German bases would be around two hours. However, any action would increase fuel consumption and reduce the time available in the air and, in fact, a typical sortie would be about two to two and a half hours.
Now three or more hours was quite a long time to spend sitting in the fairly confined space of a Hurricane cockpit and some of the intruder pilots used to joke that an essential characteristic of those carrying out such operations should be a tough posterior.