The first night fighters to operate in 9 Group were a section of 29 Squadron Blenheim Mk IFs which had arrived at Tern Hill in August. The detachment was only on loan from 12 Group and it was detailed to provide one aircraft at immediate readiness and another two at fifteen minutes’ readiness. No. 29 Squadron crews operated along a number of patrol lines, one of the first of which was the Mersey Blue, that covered the approaches to the River Mersey.
Under 9 Group it was superseded by the Holt Patrol Line which was routed along a series of datum points and towns. The patrols took the Blenheims on a south-westerly – north-easterly track, across Middlewich and Holt, between Liverpool and Manchester. The patrols were operated to protect the various approaches that the enemy used to attack Liverpool and Manchester but they proved to be no deterrent.
The three-seat Bristol Blenheim first flew in 1935 and was a
technological quantum leap among RAF aircraft at the time. With a top speed of
around 428kph/266mph, the Blenheim bomber was considerably faster than the
290kph/180mph Hind biplane it replaced and it could outrun many contemporary
fighters. The first Blenheim fighter, the IF, was proposed as a long-range
fighter that could escort bombers over hostile territory and also carry out
ground attack missions of its own. Around 200 Blenheims were modified for these
fighter duties, additionally armed with a gun pack beneath the fuselage
consisting of four machine-guns. The type had first entered service in December
1938 and by September 1939 there were 111 Blenheim fighters in use with the RAF.
Unfortunately the Blenheim could not match the performance of aircraft such as
the Messerschmitt Bf109 and so many became nightfighters, ultimately carrying
the new and highly secret airborne radar.
Even before the IFs were equipped with radar they achieved
some nighttime victories – in June 1940 No. 23 Squadron destroyed a Heinkel 111
bomber over Norfolk. The first ever radar interception came in late July when a
Blenheim IF of Tangmere’s Fighter Interception Unit destroyed a Dornier Do 17
near Brighton.
The pioneers of the Blenheim nightfighters were a flight of
No. 25 Squadron who were in fact the first unit in the world to operate
radar-equipped nightfighters. But Blenheim fighters continued to operate in
daylight too and as late as August 15, 1940, during the Battle of Britain, No.
219 Squadron were in action against a German raid on north-east England.
Between November 1939 and March 1940, RAF Coastal Command also operated IFs
providing top cover for shipping. The Mark IVF was again a long-range fighter
version of the Mark IV bomber, carrying the same gun pack. Around 125 served
with Coastal Command, providing shipping with air cover, as had the IF. In ApriI
1940 a pilot of No. 254 Squadron shot down a Heinkel 111 that posed a threat to
British ships off the coast of Norway.
#
In October 1938 the Air Ministry belatedly recognized that
there might be a need for a long-range escort fighter with two engines. Lord
Dowding told me this was principally because of the existence of the
Messerschmitt Bf 110, which required a response. It ordered an emergency ‘crash
programme’ to convert Bristol Blenheim light bombers as the only suitable
aircraft available. Even this, be it noted, had nothing at all to do with night
fighting. In 1938 the Blenheim was still regarded as a modern machine of
outstanding performance; it could, for example, easily overtake the Gladiator
single-seat biplane fighter, which had entered service only the previous year
and was fast becoming the RAF’s main day (and night) fighter. Contracts were
placed with the Southern Railway’s Ashford (Kent) works for an eventual total
of over 1,300 gun packs, each containing four of the reliable Browning
machine-guns which had been designed in the United States as a 0.300 in calibre
weapon in 1916, used in the First World War, adopted by the Air Ministry in
1934 (in the absence of any modern British gun) and put into production by the
BSA company following a licence agreement of July 1935. The four-gun pack for
the Blenheim was bolted on under the bomb bay, in which were stored the four
belts of ammunition each containing 500 rounds, amply meeting the requirement
for twenty seconds’ continuous firing (see drawing above). The railway workers
met every tight schedule imposed upon them, and also delivered several other items
making up each aircraft kit. Other companies supplied the reflector sights and
extra armour to give some frontal protection. The first contract was for kits
to convert 200 Mk I Blenheims into the Mk IF fighter, and these began to enter
service in December 1938 with No. 25 Squadron. Later contracts covered the
conversion of the long-nosed Mk IV into the IVF. These makeshift long-range
fighters were among the busiest aircraft in the RAF during the first two years
of war.
Had the conversion not been ordered it is difficult to see
what aircraft might have been used to carry the first operational AI radar
installations. By 1939 the AI Mk I, with its heterogenous assortment of
hand-fitted parts and wiring, which made no attempt to comply with any
airworthiness standard, had been replaced by AI Mk II, which was broadly
similar but was a properly designed installation which had been
‘productionized’ and improved by industrial firms. Main contractor for the
transmitter was Metropolitan-Vickers, while the receiver was made by Pye (the
chassis was based on a commercial TV set). A main subcontractor was A.C.
Cossor. The installation weighed about 600 lb, and exerted only a slight
detrimental effect on the Blenheim’s performance. At high power settings an
AI-fitted Blenheim could usually reach 250 mph without trouble, which was ample
to overhaul a lumbering Heinkel. On the other hand, it was much too slow to
catch a Ju 88 that had become jittery and ‘poured on the coals’; even a cruising
Ju 88 or Do 17 was hard to overtake. One felt that lack of a properly designed
long-range or night fighter was something that might have been avoided.
Inside the Blenheim Mk I there was a distinct absence of
room, which must have been worse with radar fitted. The pilot sat on the left
of the nose, his seat, instrument panel and controls filling exactly half the
width of the fuselage. If a dual instructor station was added on the right, the
two pilots rubbed elbows. Most of the nose structure comprised twenty flat
Perspex panes, which reflected illuminated items in the cockpit and interfered
with external night vision. The highly rated Mercury engines were reliable, and
seldom put the pilot in the rather marginal position of having to go round
again on one, with landing gear and flaps down. Behind the pilot, facing aft,
the AI operator fiddled with his box of tricks and tried to get intelligible
blips so that he could tell the pilot which way to steer (he had to remember
which way he was looking and not muddle left and right). In an AI chase he had
no time to clear stoppages with the guns or do anything but look into his
viewing hood, which was retained even though it was dark in the middle of a
Blenheim at night. Usually a third man, the observer, was also carried; he
manned the turret, with a Vickers K gun, and tried to live up to his name.
The world’s first radar-equipped night fighters resulted
from a secret minute from the Air Staff dated 17 July 1939, calling for the
fitting of radar to twenty-one Blenheim IF long-range day fighters ‘as quickly
as possible’. The document continued, ‘A requisition is enclosed incurring an
expenditure of approximately £4,650 to cover AI transmitters, receivers and
associated equipment.’ (Though the comparison could hardly be more meaningless,
twenty-one AI radars in the year 2000 would be likely to cost something over
£10 million, provided they were already in full production.) The AI II sets were
delivered quickly by Pye and Metrovick, and much of the material needed for
installation was bought by local purchase by the RAE at Farnborough, which did
the installation with the help of engineers from Bawdsey. AMRE itself was being
torn apart ready for emergency evacuation, in a badly planned way, to Dundee
and other locations.
Despite this upheaval, AI staff were able to help at
Farnborough, and deliveries of improved Blenheims began to 25 Squadron on 31
July 1939. When the Second World War began on 3 September a total of fifteen
aircraft had been delivered, and the last of the twenty-one was in service by
the end of September. All these aircraft had a much more sensible interior
arrangement. The useless dorsal turret was removed and replaced by a hatch. In
theory a Vickers K machine-gun could be fired from this for rear defence, but I
cannot imagine this ever being done. The important thing is that removal of the
turret enabled the bulky and heavy radar to be moved aft to preserve the
aircraft’s centre of gravity in the correct place. Its viewing scopes could now
face aft, so the operator no longer had to think in terms of mirror images
before giving directions to the pilot. There was no longer a need for a third
crew-member.
In November 1939 three of these Blenheims were delivered to
a special flight of 600 (County of London) Squadron, Auxiliary Air Force, at
Manston. Here they did special trials, in addition to crew training, and in
early 1940 formed the nucleus of the Fighter Interception Unit (FIU), which
grew rapidly and built up a collection of many kinds of fighter in its task of
solving every sort of interception problem. Other early Blenheim night fighters
were issued in ones and twos to existing Blenheim IF squadrons, beginning with
25, 29, 141, 601 and 604. The RAF grapevine buzzed with talk of ‘Magic Mirrors’
– talk which, as is traditionally the case with new RAF equipment, became
slightly soured. The Magic Mirrors were difficult to use, and results in
training flights varied from poor to non-existent. A basic snag was that the
target was seen, if it was detected at all, in a position relative to the
aerials on the fighter. If the fighter banked, the apparent target position
moved in response, and it was eventually judged that ordinary Blenheim crews
would have little success unless their aircraft was flying straight and level.
Another of the many problems was that, unless the target was within a 20° cone
ahead of the fighter, the aerials gave ambiguous indications; for example, the
target could be to the upper left, or at the same angle to lower right. It was
also impossible to get clear indication unless target range was between 5,500
and 1,200 feet, and the equipment was almost useless at heights below 8,000
feet because of the ground return. From the start of the war low-flying
aircraft, mainly He 115 seaplanes, had laid mines by night in the Thames
estuary and elsewhere round the coast. Early AI radar was completely useless in
trying to intercept them, though some crews tried to spiral down from directly
above. Bearing in mind that most crews were not very experienced, and still
found it hard to add two and two correctly while trying to navigate on a
pitch-black night, it is easy to see that successful radar interceptions even
at high altitude proved consistently elusive.
By October 1939 some of the difficulties had been at least
partly rectified with AI Mk III, which had first flown in August. This had
similar circuitry but a new aerial system which gave fewer ambiguity problems.
The transmitter sent its pulses from a pair of swept-back dipole aerials,
looking like a harpoon, on the Blenheim’s nose. Two similarly inclined dipole
aerials well aft on one wing picked up reflections from the target and sent
them to the elevation circuitry to show whether the target was above or below.
Two pairs of plain vertical dipoles on the outboard wing leading edges did the
same to indicate azimuth, left or right. The different signal strengths
received in the various aerials made the bright blips grow longer or shorter,
and displaced above or below, or to left or right, of the time-base centrelines
on the observer’s display scopes. It still took a long time to get repeatable
and reliable operation, or to interpret the indications correctly.
On 14 February 1940 an Air Ministry appreciation tried to
look on the bright side: ‘In the general disappointment over the behaviour of
AI Mk II and III it is possible that the limited but very real advantages of
this equipment have been overlooked.’ The implication is clear: there were
influential people incapable of seeing beyond the existing situation who were
calling for AI radar to be abandoned as useless. Had they won the day it would
have been serious for Britain, and later for the United States.
After the original crash programme to equip twenty-one
Blenheims with AI Mk II, all AI installation was done by 32 Maintenance Unit at
RAF St Athan, Glamorgan (South Wales). St Athan was a large base, and the
arrangement was at first ideal because, after a disastrous few weeks in Dundee,
AMRE was again moved, to St Athan. Here more than sixty Blenheims were fitted
with AI Mk III during the first six months of 1940. All stripping out, rewiring
and preparation with brackets and aerials was done at St Athan, but many of the
aircraft were actually fitted with the transmitter and receiver at FIU, which
moved from Manston to Tangmere. FIU organized training courses for aircrew, and
the handful of crews that could claim to be proficient began the practice of
continually visiting the operational squadrons. Night fighting was a new
technique, which made the most severe demands on crews. More than in any
previous type of warfare, the problems, the techniques and the equipment never
stayed the same but were constantly changing.
#
During that long, hot summer of 1940 hundreds of night
missions were flown over southern England with AI radar, many of them in the
face of the enemy. Success was conspicuously absent, and combat reports tended
to revolve around all the usual snags: ‘low oil pressure . . . ASI u/s . . .
had to switch off right engine . . .’, plus ‘hopeless intercom’ (now of vital
importance to get near the enemy at all) and new ones peculiar to night
fighters: ‘severe shock as I touched the firing button’, and ‘interception
abandoned when the AI set started to burn’. In the first of five interceptions
on the moonlit night of 18 June the pilot of a Blenheim who had seen an enemy
bomber visually was shot dead by a short burst from the Heinkel’s dorsal
gunner. Five He 111s were downed on that night, but all by day fighters; nearly
all the Luftwaffe losses on those summer nights were caused by Spitfires, and a
few Hurricanes, which went up hoping to catch someone held in a searchlight
beam. Then at last, on 22/23 July, a Do 17 was shot down after a true
AI-directed interception. The Blenheim was flown by F/O Ashfield, with P/O
Morris as observer and Sergeant Leyland as AI operator. Ashfield’s combat
report was tantalizingly brief, commenting in one sentence on how they were hit
by debris from their victim and then discovered that they were at a low
altitude in an inverted attitude.
Could a crew of three really get upside down without being
aware of it? The answer is, emphatically yes; an AI chase took every atom of
one’s conscious attention. Irrespective of whether the AI operator had clear
unambiguous blips or a maddening flickering fuzz, trying to decipher the true
position of the target and pass steering commands to the pilot was more than a
full-time job. There was no chance of attending to anything else. It was the
simplest thing in the world to make one’s gyro instruments topple, and in the
cold, clinical concentration of closing for the kill I almost believe a wing
could come off and not be noticed.
In the midst of all the excitement the few really great
brains involved were always able to spare a moment to take a broad look at the
problem. It was Tizard who made sure that one point of fundamental importance
was not overlooked. In May 1940, in writing an appraisal of the use of AI
radar, he commented, ‘We have insufficiently considered its use by day,
especially in cloudy weather.’ Tizard never ceased to prod the Air Ministry
into giving the most careful consideration of every new idea that was not
openly ridiculous. By 1940 sound location was fortunately dead, but infra-red
(heat) methods were very much alive, and an IR detector was flight-tested. The
brightest IR team was led by young Dr R.V. Jones at the Clarendon Laboratory,
Oxford. Director of the famed Clarendon was none other than Lindemann, whose
antipathy for Tizard was equalled only by Tizard’s for him; as Tizard had for
over twenty years been the only rival to Lindemann’s claim to be most senior
defence scientist, the problem may be self-evident. Watson-Watt managed to
sidestep political feuding, to his own and radar’s benefit. It was Tizard who
suggested that Jones might leave the Clarendon, though in 1937 his IR detector
had sensed other aircraft at a range of just over 1,500 feet, and was easier to
package and use than AI radar. Maybe Tizard was gifted with foresight to see
that IR would for many years to come be thrown off the scent by fires on the
ground, by the Sun and even by sunlight reflected from lakes and rivers. It was
almost certainly a correct decision in 1937 to drop IR detection, though the
technique returned in the 1950s, as will later be related.
Other techniques included searchlights and aerial mines, as
well as an increasingly long list of impractical suggestions helpfully sent in
by the public. As noted earlier, use of as obvious an idea as the airborne
searchlight simmered during the First World War (but was never actually used)
and emerged again with the sudden mushrooming of air defence in the late 1930s.
Most of the airborne-searchlight effort prior to the outbreak of the Second
World War comprised paper studies and argument, whereas reason suggests that it
would have been more sensible to do a few cheap experiments and see if the idea
worked. Instead, little or nothing was done until the night blitz was actually hitting
the country in the closing months of 1940, as will be recorded in the next
chapter. The same is true of almost all the other ideas, including mines. It
was even true with the fundamental fact of how far a night-fighter pilot might
be expected to see at night. This highly variable factor was self-evidently one
that demanded the most carefully designed scientific research in an attempt to
get meaningful numerical results. Instead the Air Staff, Air Ministry, the
scientific committees and even night-fighter pilots did nothing but argue –
quite literally a case of heat overcoming light. The CH system’s limit of
accuracy of between three and five miles was much too far to be of any use at
night; Dowding said, ‘It might as well be fifty miles.’ Hence the urgent and
crucial need for an additional sensor – Churchill always called it a ‘smeller’
– carried in the fighter. Despite Jones’ neat IR installation, it was clear
that it would be AI radar or nothing.
In the closing months of 1939, while the AMRE research team
was uprooted yet again and set up shop at Worth Matravers, near Swanage on the
Dorset coast, their masters in the Air Ministry became increasingly concerned
about the basic AI radar problem of minimum range. AI Mk III had a maximum
range of two miles (say, 10,500 feet) and a minimum range of 1,000 feet, though
in those days AI was temperamental and actual results were less predictable.
Frankly, even AI Mk III was pretty useless except for the vital task of
training crews. For the stern test that could come at any time there was an
overwhelming need for an improved AI radar with minimum range as near as
possible to 300 feet, and with clearer and more positive left/right up/down
indication than the ‘squint-eyed’ Mk III. With the coming of war, the whole
British defence scene had changed dramatically. Radar, previously the secret
preserve of a tiny team of ‘back-room’ workers, suddenly gathered into its fold
fresh manpower by the hundred and soon by the thousand. Watson-Watt personally
scoured the universities to scoop up bright talent and open their eyes to the
scarcely believable facts that in a government defence laboratory it was
possible to find academic freedom, a most enjoyable atmosphere, and technical
problems as gripping as any posed inside ivory towers. Industry, too, was
harnessed in the biggest possible way to provide brainpower and manufacturing
capacity.
It was mainly the newcomers that were to make the dramatic
breakthroughs in AI radar. Everything – minimum range, inability to focus into
a narrow beam, and inability to intercept the low-flier because of the ground
echo – kept emphasizing the need for much shorter wavelengths. Nobody knew how
to generate enough power at short wavelengths, but in fact one major hurdle had
been crossed back in 1921 in Schenectady, when Dr Albert W. Hull, of the US
General Electric Company, had described a novel valve he had devised and named
the magnetron. Many workers improved it during the inter-war years, but in
essence it remained a resonant-cavity device like an organ pipe or other wind
instrument. Unlike almost every other oscillator the magnetron could generate
energy at fantastically high frequencies, with wavelength down to a few
centimetres; but power was still very small. Much later a quite different valve
called a klystron was invented, mainly by W.W. Hansen at Stanford (who devised
the crucial part, the rhumbatron) and the Varian brothers. In the klystron the
main structure is a special CRT, whose steady pencil-beam of electrons is
turned into a succession of intense bunches by one rhumbatron and then caught
within another. Both the klystron and the magnetron could generate waves so
short they were called microwaves. By the end of the 1930s brilliant workers at
MIT and Bell Labs had developed the basic theory of waveguides – essentially
just very accurate metal pipes – for carrying microwaves and, by physically
adjusting their dimensions, for tuning the waves to exact wavelengths. It was a
new and exciting field, pioneered in the United States but, like normal
scientific research in peacetime, freely published.
Shortly after the start of the Second World War Watson-Watt
gathered some of his best captures from the universities and – after assuring
them that, though they had arrived on ‘the Shanghai express’ they had return
tickets – asked them to think about microwave radar. Some of them knew enough
about the subject to know that it could not be done, except with uselessly
feeble power. A few others thought it worth chasing, but doubted that anyone
could build a receiver. By the end of September 1939 two groups had used their
return tickets, but only so that they could go back to work on the problem in
their own laboratories. One group under Professor Mark Oliphant returned to the
University of Birmingham to study transmitters. Another under J.H.E. Griffiths
went back to the Clarendon Laboratory to work, in partnership with the
Admiralty (under C.S., later Sir Charles, Wright, Director of Scientific
Research), on the receiver. It was a mighty task. Every previous attempt to
generate powerful microwaves had merely dissipated the energy into the
atmosphere, or into heating the hardware (at least once it actually melted). No
way was known of building any kind of practical radar on a centimetric
wavelength. Indeed, almost a year later a VIP in the scientific world, leading
a party of visitors to see the first demonstration ever given of what can
fairly be called ‘modern radar’, summed up rather loudly by saying,
‘Centimetric radar is for the next war.’
In the first month of war such a comment could not have been
disputed, because nobody then knew how well the shanghaied men from Birmingham
would do. In the meanwhile conventional 1.5-metre AI had to go ahead with all
speed. There were quite suddenly a succession of minor breakthroughs, the
greatest of which was the development of a new modulator by A.D. Blumlein of
the His Master’s Voice gramophone company (the electronics giant EMI). This
dramatically cut the time duration of each pulse, and overcame the problem of overlay
at the receiver by the direct pulse from the transmitter. The General Electric
Co. (no relation to the US giant) began its radar career by producing a smaller
yet far more powerful main transmitter valve, the Micropup, giving 10 kW on 1.5
m (190–195 MHz). It was hardly bigger than a household filament light bulb.
W.B. Lewis, an AMRE newcomer, achieved a breakthrough with minimum range. The
resulting radar grew to have little left of AI.III save the aerials; receiver
gain and time-base deflection were increased, and the boxes were so arranged
that a single technician could adjust settings with a screwdriver and
simultaneously watch the tube-faces (previously he could not do both). The
result was AI.IV, the first AI radar that could give real results in Service
hands, and the only one in quantity service until late 1943. Provided that a
target was within a 40° cone ahead of the fighter, its direction could be
indicated unambiguously within 10°. Straight off, in September 1940, Pye was
given a contract for 600 sets, with major assistance from EMI.
Thus, during the crucial summer of 1940, there were already
in Britain three generations of AI radar, discounting AI.I and II. They were
separated in timing by weeks rather than years, yet such was the pace of development
they were utterly dissimilar. Mk III was primitive, the minimum that could
reasonably be supplied to the RAF. Mk IV was better, yet still a 1.5 m set with
all that wavelength’s inherent shortcomings. Still in the laboratory was the
new generation using centimetric microwaves. (Incidentally, the FIU was very
proud of the fact that, despite not being an operational unit of the RAF, its
crews shot down the first enemy aircraft to be destroyed by every type of AI
from Mk III to Mk X.) But despite all this work by the ‘boffins’, the
night-fighter strength of the RAF was woefully small. Almost the whole
establishment of Fighter Command comprised Hurricanes (about thirty squadrons
in mid-August 1940, despite terrible losses in France) and Spitfires (about
nineteen squadrons), few of whose pilots had even tried flying at night, and
which could find night raiders only by chance. There were a few squadrons of
Gladiators, some of which had done a little night flying, and an embryonic
night force of Blenheims and Defiants. In September 1940, when the night blitz
started in earnest, Fighter Command had, for all practical purposes, six
squadrons of Blenheims and three of Defiants for night fighting. About
one-third of the Blenheims had AI.III, and there were still a few AI.II
installations.
This modest night-fighter force would still have been of
little use without four further technical developments which formed vital links
in the chain of aerial defence. One was a grand design called GCI (ground
control of interception) which owed much to W.S. Butement, who had proposed a
50 cm naval radar at the Signals Experimental Establishment as early as 1931.
GCI included CHL (chain home, low) and gap-filler radars to cover the lower
airspace, but the main item was a radar giving a picture showing the positions
of fighter and bomber. The second essential was IFF, already mentioned, the
earliest example of so-called secondary radar. Fitted to all friendly aircraft,
it was triggered by the defending radar pulses to send back an enhanced and
specially coded reply. Thus, when ‘interrogated’ by either a ground station or
a night fighter, the ‘friendly’ would automatically show up on the display
screens in a characteristic way, without its aircrew even being aware of what
was going on. A ‘hostile’, on the other hand, would not know the IFF code,
which was constantly being changed, and thus its radar ‘blip’ would be
suspicious. However, it could not just be shot down without visual
identification, because it might be a ‘friendly’ with its IFF unserviceable, or
even just switched off. Over the years IFF, like ECM, was to grow fantastically
in complexity and cleverness, and to give rise to the modern field of secondary
surveillance radars (SSR) and transponder beacons. The third new development
was a related system of Racons (radar beacons) placed in a chessboard pattern
over southern England to give an equally distinctive blip on night-fighter
radars (AI.IV onwards) and thus help the fighter to return safely to base.
One could overlook the fourth link in the chain, unless one
had been a pilot at the time. Aircraft had previously used HF radio, which
suffered from ‘static’ and speech distortion so badly that to a layman any
received message sounded like unintelligible gibberish. Even professional
aircrew often had to request, ‘Say again’. In 1940 VHF (very high frequency)
radio arrived with marvellously clear speech just in time to play its vital
part in the night battle. The fact that it had shorter range was of no
consequence. With it came a standardized GCI language. Today one is amused, but
in 1940 the GCI command, ‘Flash your weapon’, caused not a trace of a smile: it
came at a time of mounting tension in the chase, and meant ‘switch on your AI
radar’. ‘Increase speed’ was partnered by ‘Throttle back’, and at the end of
the interception the crew would be told ‘Darken your weapon’.
It needed all these new inventions and techniques to
construct an effective scheme of night defence. It is unfair to describe it as
sheer luck that it all came together in the autumn of 1940; it was planned with
great care and forethought, and had it not been for the fact that the Air
Ministry Works Department – responsible for civil engineering and buildings –
stubbornly resisted every attempt to substitute speed in place of perfection,
almost the entire scheme could have been operational by the beginning of the
war. For the first time in history it enabled a country to wait until hostile
aircraft were approaching, and then send fighters where they were most needed.
The only shortcoming was that the GCI system alone could not put fighters in
visual contact with the enemy at night. Modern air traffic controllers will see
the problem only too well. Their job today is to keep aircraft apart; in 1940
the task was to bring aircraft together, and to do it with primitive radars
giving very ill-defined blips that flickered and jumped and sometimes just
disappeared for no obvious reason. Visual contact at night meant a few hundred
feet, whereas the best accuracy a really good GCI controller could hope for in
1940 was more than three miles. Even then, the fighter had to be going in the
same direction at the same height. There were countless other snags, not least
of which was the fact that the 1940 controller himself had little experience.
Until many months had been spent sifting unsuitable people, he often lacked an
understanding of the fighter pilot’s problems, and often also lacked the right
kind of confident patience and encouragement that was vital to proper teamwork.
Controlling was an art.
Few indeed were the people in night fighting who in 1940 had
any artistry, experience or even confidence. Come aboard the Blenheim night
fighter of F/O (later Air Commodore) Roderick Chisholm, as he tried to learn
basic steps in the new trade at Middle Wallop that summer:
I was kept waiting,
signalling for permission to land but ignored, for about half an hour. I was
anything but composed, and when a turn proved too much for the directional
gyro, which spun, I also lost my sense of direction. At last I was given a
‘green’, but the dim pattern of aerodrome lights made little sense by this
time, and my approach to land was not aligned with the flare-path, whose
direction I understood too late. I had to go round again. The wheels and flaps
on a Blenheim came up rather slowly, and by the time I was ready to start a
circuit I knew that I was several miles from the aerodrome; but I could not
picture my position, and the lights which I could see did nothing but confuse
me. I was flustered, and the situation suddenly got out of hand. I did not know
where I was; therefore I was lost. A feeling of panic came over me, and I could
not think of anything except getting down somehow on to terra firma. It must be
this paralysis that causes the inexplicable night-flying accidents. It took a
great effort for common sense to overcome this one instinct, which seemed still
to work, to return to earth as soon as possible; but slowly this happened and
item by item things were checked. What height? What speed? Climbing or diving?
Where was I likely to be? Each of these checks, usually done instinctively and
instantaneously, now needed a special effort . . .
There’s a beacon –
what’s it flashing? – dot something, missed it – climbing too steeply, must
level out – now, where’s that beacon again? – get the beacon paper (it’s too
flimsy) – where’s the torch? – mustn’t get flustered again – there’s plenty of
time – climbing again, must level out – Andover VL, Wallop DA – now, where’s
the beacon? – there it is, think clearly, read it slowly – looks like a V then
L – read it again, there it goes again: it’s Andover – about 240° for Wallop –
settle down, align the gyro – steady – lights ahead – a beacon – flashing DA,
that’s Wallop – this is simple – I could go on, I’d like to go on now – this
will be a joke tomorrow.
I doubt that there is
a single pilot who does not have similar memories from his early days when it
all seemed to be just too much. Flying by night could bring the feeling
flooding back – often fatally – to pilots who, like Chisholm, had long
experience in daylight. For almost a year such men tried to master the Blenheim
by night, while an experienced few operated AI-equipped aircraft at FIU and,
increasingly, in the squadrons. Not many German aircraft came over at night to
begin with, but FIU mounted night patrols to see if they could intercept any,
and from 5 June 1940 AI was used in real chases of real targets. Time after
time the enemy got away, usually because the harassed AI operator could make no
sense of the erratic blips of the shaky Mk III and was incapable of giving his
pilot clear steering commands. The only exception was Ashfield. His was the
first of a handful of victories gained by the NF Blenheims. Courageously flown
for long, cold and exhausting patrols night after night, they simply lacked a
good enough AI set to complete the chain of defence. Unlike most other
fighters, including the Defiant, their guns could be fired on the darkest night
with no flash problem. Performance, however, was marginal, even after the
Blenheims had had their turrets removed in September 1940.
