"Bandits" of the German Luftwaffe and "thieves" of the Japanese air force took advantage of the dark of night during early phases of the war to operate undetected against Allied cities, military concentrations, supply lines, and airstrips. Then something in the way of black magic was performed by Allied forces which no longer would permit the enemy to attack at will, without opposition, under the cloak of darkness.
The "something" was the perfection of night fighter tactics, the most important part of which is the use of radar developed to such a degree by Great Britain and the United States that its present usage and future possibilities are amazing.
The best pilots and the best-trained airmen are the men who do our night fighting in the air, ranking AAF officers say. Judging from the multiple training these flyers get, and their results against the enemy, they have been described properly.
Night fighting in the air is not new, but the present radar equipment is. In the first World War, British night fighters operated unaided in the dark to intercept German Gothas and Zeppelins. By the end of that war the British had worked out a haphazard system of defense between the interceptors and ground searchlight units to combat the German aircraft, but that was all.
In this war, the same night defense problem again confronted the British, particularly in 1940 during the Battle of Britain. From bases facing the length of the British Isles, the Luftwaffe carried out large-scale daylight bombing raids against English cities. Through the use of radar, these raids were broken up by valiant pilots of the Royal Air Force, flying a comparative handful of Spitfires and Hurricanes.
The resulting heavy daylight losses forced the Luftwaffe to start mass bombing operations at night. Here again, as it did during the Battle of Britain, ground-operated radar saved the British. Approaching enemy aircraft were detected and tracked by the British stations even as they climbed up from their airfields in France.
But this was not airborne radar. The first airborne radar set was installed on British Blenheim twin-engined medium bombers. This plane was big enough to carry the radar set and a radar operator to direct the pilot in intercepting the enemy raider.
However, Blenheims soon proved unsuitable because of their unsatisfactory rate of climb, speed, maneuverability and firepower necessary for night fighters. The radar unit also was too unstable for consistent operational work and became a maintenance headache. There also was a lack of ground control and aids to navigation necessary for safe and effective operations.
The British persisted, however, and constantly made improvements on radar equipment. They elected to install the newer equipment on Beaufighters two-place, twin-engined fighters with a top speed of 325 mph at 16,000 feet. This was a wise choice, proved on the night of May 10, 1941, when /Beaufighter pilots shot down 33 German bombers.
Meanwhile, ground radar stations were being developed to a greater stage of perfection. In addition to helping the night fighters locate their prey, they coordinated their findings with the searchlight control, which would send searchlight beams into the sky to direct defending airmen to the enemy bomber concentration. Once the airmen made radar contact with enemy planes ground lights would be doused and the interceptions would be run in radar-directed darkness.
One derivation of this, which was attempted and soon discarded, was the installation of a powerful searchlight in the nose a Douglas Havoc. Using radar, the Havoc would close in on the bomber at its approximate position, then turn on the powerful beam to illuminate the bomber. Hurricanes flying close to the Havoc would swarm in to carry out the attack. This was soon found impracticable and was discarded.
As radar improved, the RAF gradually replaced the Beaufighters with Mosquitoes for the night shift. The twin-engined, light Mosquito had speed, high rate of climb, good visibility and maneuverability, plus the firepower of four 20-mm cannon and four .303-caliber machine guns. It is the principal night fighter used by the RAF today [mid-1945 JLM].
First night fighter used by the AAF was the Douglas P-70, a cannon-carrying, radar-equipped version of the Havoc. Because of its inability to perform satisfactorily above 20,000 feet, the P-70 was replaced in 1943 by the Northrop Black Widow (P-61 in the AAF, FT-1 in the Navy), designed specifically as a night fighter. Capable of high performance above 35,000 feet, the Black Widow is faster than any enemy bomber, carries the latest in radar interception equipment, four 20-mm cannon and four .50-caliber machine guns, is highly maneuverable, and carries a crew of three.
The first American aircraft ever to be designed right from the beginning as a night fighter, the Black Widow flew for the first time on May 26, 1942, is powered with two 2,000-hp Pratt & Whitney R-2800 engines. Wing span is 66 feet, length, 48 ft 9 in, height, 14 ft.8 in. Fully loaded, it weighs 26,000 pounds; wing loading is reported to be just over 50 lbs per sq ft. Another report says the Black Widow landing speed is approximately 100 mph, although one is supposed to have been flown at 74 mph with wheels down, without stalling.
The basic facts about the radar installed in the Black Widow have just been passed on to the public for the first time by the Office of Censorship, though its basic principles were discovered 25 years ago. It is radar that makes the night fighter as we conceive it possible.
Briefly, the radar set emits a series of short pulses of radio energy which are reflected back to the sending unit from any object they strike. They travel at the speed of light 185,000 miles per second. Ultra-high frequency radar sets transmit and receive a reflected energy "echo" off the target at the rate of several thousand times per second, making it possible to focus the transmitted energy into a narrow beam.
Measurement of the time elapsing between the transmission of a pulse and its return echo determines the distance of the target. This is accomplished by the use of a cathode ray tube, which creates an electronic beam that can "tone down" the tremendous rate of speed with which the wave is sent and reflected, making it definable. The reflected beam is then transformed onto an oscilloscope, which is in the form of a circular dial. The echo appears as a mark of light on the fluorescent scope and enables the radar operator to determine the range and direction of the target. Another scope is used to fix the altitude.
Radar used in Black Widows is known as airborne interceptor equipment (AI), while that used on the ground is ground control of interception (GCI). At GCI the radar operators can detect the approach of a "bogey," or hostile aircraft, and constantly plot its flight path and altitude. Black Widows then can be vectored to the vicinity from the ground and placed in attacking position all unknown to the enemy. Then they take over with their AI equipment, which is extremely accurate and which enables them to get the fighter into firing position.
Here a whole new vocabulary peculiar to night fighters comes into use. The "RO," or radar operator, sits in the rear of the P-61 crew nacelle, operating his AI and keeping the pilot and gunner up front continuously aware of the position, altitude and approximate speed of the target on which his radar beam is focused.
"No joy" means that the night fighter has not yet made contact with the "bogey." The word "contact" means that the RO has picked up the enemy. Here is where the GCI personnel sweats it out. Although it is only a matter of minutes, it seems a short lifetime before the word they want from the pilot comes through.
That's it! That's what everyone has been working to hear since the bogey was first picked up on the scope. It means the enemy has been shot down.
Training of AAF night fighter crews started in this country. A base was set up at an old fighter command school at Orlando, FL, where some of our pilots and radar observers who had been trained in England were to serve as instructors. Pilots .received flight training in P-70s, while the ROs practiced with AT-11s (the Beech Kansas). It was not until September, 1943, that the first Black Widows arrived at Orlando and the study of night fighter tactics could be learned together by the pilots, gunners and radar observers. In January, 1944, the entire program was moved to Hammer Field, Fresno, CA, where more than 1,500 night fighter airmen have been turned out to date.
Hammer Field is the only AAF base where night fighter tactics are taught exclusively. Here, the three-man crews flying Northrop Black Widows are woven into teams which go through an entire tour of duty together, separated only by accident or enemy action.
Every pilot who goes to Hammer Field already has earned his wings and is commissioned either a second lieutenant or flight officer. Further, he has professed an ambition for night fighter work and has received additional training at Douglas, AZ, in Mitchell transition bombers, taking an extensive course in instrument flying in these twin-engined aircraft.
When he arrives at Hammer Field, his flying training practically starts anew. In primary stage he is given more instrument flying in ground school and 20 hours in the air. He must reach a high degree of efficiency and have complete confidence in his P-61.
During primary training, pilots team up with their operators. They don't work with radar as a team during this period, because the pilot is too busy learning to fly. This is an extremely important time, however, for the pilot and radar operator. It is the time they are becoming close, inseparable friends and learning each other's flight habits. If the two don't get on too well together, they are diplomatically separated and teamed up with someone more companionable to each. The AAF and the Fourth Air Force have found that the closer the pilot and radar operator, the better chances they have to destroy the enemy and get back home safely.
In the basic training phase, the pilot and RO are given several hours of dual instruction in modified Martin Marauders (TB-26), with a pilot instructor and radar operator instructor. The crews also fly tactical interception missions in Black Widows both day and night during this phase.
Advanced training ends their three month course at Hammer Field. During the advanced phase they learn high- and low-altitude night flying, advanced interception tactics, evasive maneuvers, closer coordination with GCI, and aerial gunnery at nearby Hayward Field. The fourth month of their course is in aerial gunnery, which is given at nearby Hayward Field, where training also includes skip bombing, ground gunnery, and so on.
Through all night fighter training the airmen learn the importance of their ability to see through the almost impenetrable blackness of the darkest night. Therefore they are thoroughly indoctrinated in night vision a subject of vital interest even to the foot soldier. This course includes a simple description of the anatomy of the eye, the histology of the retina and the mechanics of vision, with emphasis on contrast between rods and cones, and central and peripheral vision. [Also see "Night Eyes for Airmen," Flying, January, 1945.]
The human eye, the airmen are told, is made up of cells known as cones and rods. The cones comprise the exact, dark center of the eye and are used in daytime or in artificial light to focus directly on the object to be seen. The rods make up the outer ring of the eyeball and are responsible for night vision, with the object to be seen best discerned by looking about 15° above, below or on either side of it.
It takes from 30 to 40 minutes for the eyes to become thoroughly adapted to night vision. Therefore, those who fly at night are often seen wearing dark-red-lensed goggles which help them to become dark-adapted long before the mission's start.
Once acquired, dark adaptation is zealously guarded by avoiding exposure of the eyes to brightly-illuminated areas. Cockpit lights in the Black Widow are turned so low that the instruments cannot be seen by a person not dark-adapted, yet the pilot can see them plainly! Caught in an enemy searchlight, or when he opens up all his guns at an enemy plane, the pilot quickly closes one eye to retain perfect vision in it, opening it only when he again is in complete darkness.
Windshields of the Black Widow have to be kept as clean as possible, while their crews are required to fly on oxygen from the ground up to help retain maximum night vision. Crew members also are urged to eat just before a flight, preferably something with sugar in it, as a low blood glucose level will lower night vision.
Thus, besides their flying and radar instruction, the students undergo a back-breaking course of study which includes altitude indoctrination and aviation medicine, special communications, special air defense, night aircraft recognition, meteorology, navigation, interceptor techniques, countermeasures to overcome and offset enemy radar, and many other subjects important in their new trade.
They know the astonishing advances that science has made in radar, both as an instrument to guide our weapons of war and as an aide to civilization in general after the peace.
They know, too, that civil aviation will benefit immeasurably by radar in a relatively short time when the pilot of a huge airliner, for instance, will be able to fly through the darkest, rainiest night and come in for a perfect landing on a field he can't even see. A radar operator on the ground, who also can't see the plane, will have "talked it down" to a landing merely by reading the craft's position, range, altitude and speed on his radar scopes, relaying that information orally to the pilot.
This article was originally published in the June, 1945, issue of Flying magazine, vol 36, no 6, pp 32-34, 146, 148.
The original article includes 7 photos, including one of the P-61 in flight and one of the gunner climbing up into the plane; there is also a photo of a Havoc I Turbinlite from 1 o'clock low.
Photos credited to AAF, Sperry, The Aeroplane.