Inside the glassed-in nose of a Heinkel He 111 bomber, a pilot and his navigator/bombardier sat in silence, a silence that only they recognized beneath the blasting thunder of their ship’s two Jumo V-12 engines. Tonight was a good night to be out over England in the summer of 1942—dark and moonless. Tonight’s target was the city of Coventry—according to Tomas his navigator, just 130 miles to the west. Tomas spoke quietly on the intercom, “We are just north of Ipswich now, still another 40 minutes to go.” He was glad Tomas knew where they were. The pilot had been to Coventry a year ago, and he hoped this would be the last time. Outside the cockpit, all was total darkness, no light above or below. He no longer could see the vague silhouettes of the others, or even their exhaust flares. Just blackness. The night was a dark friend. So far so good.

Ten seconds later, the comforting cover of night was turned into the blinding light of day. In a single moment, the cockpit had become a searing blue-white room of unholy light crossed by shifting shadows. Within the light, the engines seemed to shriek like banshees. The pilot’s first reaction was incredulity—there was no searchlight that he had seen below, yet somehow it had found him the instant it was turned on. How was it possible? A millisecond later, he reefed the Heinkel into a diving left turn, with Tomas, who had stood up to move down to the bomb aiming position, slamming onto the cockpit glass on the starboard side. The beam of light seemed to follow him down and was so broad, he could not get out of its grasp. He could hear his gunners, Gerhard on top and Arno in the ventral turret hammering away at something with their MG 81s. The cockpit smelled of cordite and an odd whiff of something electrical. While the pilot corkscrewed, tracer rounds started washing by like liquid blobs of light and then rounds started thumping and ripping into his aircraft.

This fanciful scenario was what inventor Sydney Cotton, Air Commodore William Helmore (the godfather of Photo Reconnaissance) and the Royal Air Force had imagined when they invented, patented, built and deployed the 2,700 million candela Helmore Turbinlite aboard a modified Douglas A-20 Havoc (Boston) night fighter. As it turned out, the system was not successful and scenarios such as this never really happened. The German pilot and his crew would continue on to the city of Coventry that August night and, along with others, drop their bombs. It was the last raid on Coventry. Five months later, the lights went out on the Turbinlite concept forever.

By late 1940 and early 1941, the concept of the night fighter was truly coming into its own. Specially dedicated squadrons were forming with specialized tactics, equipment and training. New forms of portable radars were slowly coming into use, but mostly they were only able to get a tracking night stalker to within the general area of an operating enemy bomber. Air Commodore William Helmore, as special scientific advisor to the Chief of the Air Staff, dedicated much of his time on the subject of night fighters and their equipment and, along with Cotton, came up with a concept they called ATI—Air Target Illumination. The idea was to put a searchlight in the nose of an aircraft, and using both ground radar and new RDF (Radio Direction Finding) radar in the aircraft, guide the pilot to within striking distance of the enemy at night. At this point the pilot would switch on his searchlight, illuminate the bomber and accompanying fighters would shoot it down.

The concept of illuminating enemy aircraft at night, for satellite fighters to take out, seemed simple enough, and this alone most likely drove inventors and the RAF to push forward with the concept even as better radars were being developed. The idea was to attach the world’s most powerful searchlight to the nose of a powerful twin-engine night fighter. The light itself was designed for this specific purpose under the patents and direction of Helmore and Cotton and was far more powerful than any military light of the day. To understand exactly how powerful it was, a comparison should be made. The service searchlights in use by the Army and Navy up to this point consumed 150 amps of current. The Helmore Turbinlite drew 1,400 amps. Specially designed 12-volt batteries were created which could discharge in 120 seconds. The 48-battery array was carried in the fuselage and weighed so much (nearly 2,000 lbs) that the Turbinlite aircraft could carry no offensive or defensive armament. The light burned through its carbon rods at a prodigious rate, these being fed mechanically as they were consumed by the arcing electricity from the batteries, generating considerable heat and toxic gas fumes. The heat and gas output problem was dealt with by a chin intake which drove cooling air into the nose section and forced it out through a hydraulically-actuated vent door on the starboard side.

The working end of the Turbinlite Boston (possibly the same prototype from the previous photo)—the awesome 2,700 million candela Helmore searchlight, while bright, was decidedly not the best for aerodynamic design, with a large flat glass surfa… — The working end of the Turbinlite Boston (possibly the same prototype from the previous photo)—the awesome 2,700 million candela Helmore searchlight, while bright, was decidedly not the best for aerodynamic design, with a large flat glass surface. The outer metal ring, known in aerodynamics as a *Townend Ring*, was designed to smooth out air flow, reduce drag and increase cooling to the massively hot lamp. On the right, we see the “arrowhead” aerials for the Radio Direction Finding (RDF) equipment (as well as dipole antennae mounted on the starboard fuselage. The vent which extracted the heat and fumes from the burning carbon rods can be seen on the starboard side aft of the fairing.

Many of the Douglas A-20 Havocs employed in Turbinlite service were already on strength with the Royal Air Force. Here, an intruder Havoc I (BJ496) flies off the Irish coast very early in the war, during trials to assess various camouflage paint schemes for night fighters. The aircraft was serving with the Royal Aircraft Establishment and flying from RAF Aldergrove in County Antrim, Northern Ireland. The previous February (1940), the aircraft had been operated by 23 Squadron as a night intruder. Following these camouflage trials, BJ496 was modified as a Turbinlite Havoc (one of the first) and operated by 1422, 1451, and 1454 Flights, RAF. On the night of 23 October 1941, whilst on a Turbinlite searchlight exercise at RAF Colerne, it crashed and was destroyed. Photo: Imperial War Museum — Many of the Douglas A-20 Havocs employed in Turbinlite service were already on strength with the Royal Air Force. Here, an intruder Havoc I (BJ496) flies off the Irish coast very early in the war, during trials to assess various camouflage paint schemes for night fighters. The aircraft was serving with the Royal Aircraft Establishment and flying from RAF Aldergrove in County Antrim, Northern Ireland. The previous February (1940), the aircraft had been operated by 23 Squadron as a night intruder. Following these camouflage trials, BJ496 was modified as a Turbinlite Havoc (one of the first) and operated by 1422, 1451, and 1454 Flights, RAF. On the night of 23 October 1941, whilst on a Turbinlite searchlight exercise at RAF *Colerne,* it crashed and was destroyed. Photo: Imperial War Museum

The light itself had an elliptical reflector, which projected a horizontal “sausage-shaped” beam of light with a 30 degree divergence. This gave a horizontal light coverage of 950 yards wide at one mile ahead of the aircraft. This powerful and wide beam would light up any bomber ahead for a mile, allowing the accompanying Hurricanes (sometimes Bolton Paul Defiants early on) to spot and attack the enemy aircraft. The two parasite fighters in the team kept station on the Turbinlite Havoc throughout the chase using formation lighting on the Havoc’s wings. This lighting was in the form of a white strip along the trailing edge of the main plane on both sides, illuminated by an angled lamp. Using small elevator inputs, the Havoc pilot was to keep the beam on the enemy as the Hurricanes made their attack.

Of course, operating in relatively close formation in the dark with barely visible lighting required radio work to fully communicate in an environment where hand signals did not work. This meant that instructions and communications via radio could be detected by the enemy. A system of code words and expressions were used to communicate command and intentions—all kept to the bare minimum. The pilot of the Turbinlite Havoc, unable to see the Hurricanes on his wings would ask “ARE YOU SNUGGLING?” (Are you in formation?) If he did see the Hurricanes and wanted them to close formation, he would order this with the single word “CONTRACT” and “EXPAND” if he wished the formation to open up. When the Havoc was within 5,000 feet of the target, the pilot would declare this with the single word “WARM.. If he wanted to tell the Hurricane pilots that he was dropping back he would say “COOLER.” At 3,000 feet back, he would declare “HOT,” to which the Hurricanes were obligated to confirm receipt of the message by saying “UNDERSTAND HOT.” Ten seconds before illumination, the Havoc pilot would say “BOILING.”

The Hurricane pilot had a code as well to communicate with the Havoc in the lead. Approaching the Havoc, and in need of the formation lights, he would say “SHOW UP” and if he felt that station keeping lights were too bright, he would say “CLOSE WINDOWS”. Other signals were “I AM DESOLATE” (I have lost you), “I AM SKYLARK” (I am above you), “I AM SNAKE” (I am below you) and “I AM PANCAKING” (Obliged to return to base).

A Douglas Havoc fresh out of the conversion hangars at RAF Burtonwood’s repair and modification depot. There appears to be a cover over the searchlight’s lens. This Havoc operated as a Turbinlite aircraft with 1422 Flight and the… — A Douglas Havoc fresh out of the conversion hangars at RAF *Burtonwood’s* repair and modification depot. There appears to be a cover over the searchlight’s lens. This Havoc operated as a Turbinlite aircraft with 1422 Flight and then 1457 Flight, which became 536 Squadron. Photo: Imperial War Museum

It has been suggested that this photo of a Douglas Boston of the RAF shows it being lit up by two Turbinlite aircraft–in what could be an aerial test. Photo: Imperial War Museum via Clark Reid — **It has been suggested that this photo of a Douglas Boston of the RAF shows it being lit up by two Turbinlite aircraft–in what could be an aerial test.** Photo: Imperial War Museum via Clark Reid

The forward-firing machine guns of the straight Douglas Boston and Havoc night fighters were removed as were any defensive guns. The Turbinlite Havoc carried primitive AI Mk IV airborne interception radar, the RAF’s first air-to-air radar system. The radar was used to bring the Havoc and Hurricane hunter-killer team close to a formation of German bombers and leave the Helmore Turbinlite to illuminate the target. Operation of the radar equipment was just as much an art as it was a science and the effective use of the system depended on the experience and the ability of the operator to correctly interpret the displays on its two cathode ray tubes.

The first units to train and employ the Turbinlite Havoc were 1451 Flight at RAF Hunsden and 1422 Flight at RAF Shoreham. By the summer of 1942, there were a number of RAF Night Fighter Flights which operated the Turbinlite Havoc. These Turbinlite Flights (smaller than a squadron) would work in unison with Hurricane and Boulton Paul Defiant night fighter squadrons from nearby bases, which supplied the team’s fighters. This initial system was far from satisfactory as there were difficulties coordinating join-ups in the dark, with fighters arriving too late or not at all. It was decided that the flights should be upgraded to Squadron status and be given both Havoc and Hurricane aircraft working as a cohesive team. All of these flights would become squadrons in September of 1942. It was thought that this teamwork concept would help ameliorate the rather abysmal operational record of the Turbinlite. It did not.

In all, 10 RAF Flights were initially converted to the Turbinlite system—including 1456 Flight at RAF Honiley (and later RAF High Ercall), 1454 Flight at RAF Charmey Down, 1458 Flight at RAF Middle Wallop, 1457 Flight at RAF Predennack, 1422 Flight at RAF Heston, 1452 Flight at RAF West Malling and 1460 Flight at RAF Acklington. Each of these RAF Havoc flights (except for 1422) would eventually become one of the new Turbinlite Squadrons numbered sequentially from 530 Squadron (1451 Flight), 531 Squadron (1452 Flight), 532 Squadron (1453 Flight) etc... through to 539 Squadron (1460 Flight). Nearly 100 Havoc/Boston aircraft were converted to the Turbinlite standard in order to supply aircraft to the ten Squadrons. All of these squadrons operated both the Havoc stalker aircraft with their own Hurricane hunters and all of them would be out of operation at the end of January 1943, only a few months after being formed.

In the summer of 1942, the Turbinlite Havoc was demonstrated for King George and Queen Elizabeth. It is not known whether this was a nighttime demonstration, but likely so. This would have been an impressive sight indeed. But sadly, the combat record of the Turbinlite Havoc and its parasite fighters was not nearly as impressive. From what I can tell, there were but a few actual contacts resulting in engagements with the enemy, and it seems that only one enemy aircraft was shot down as a result of the Turbinlite system—a Heinkel He 111. In the negative side, numerous Havocs and Hurricanes were lost while on Turbinlite operations. Most tragically however, on the night of 4–5 May 1942, a single Short Stirling bomber of 218 Gold Coast Squadron returning from an operation, was tracked, lit-up and shot down by a Havoc/Hurricane team. Given the obvious good lighting provided by the Turbinlite, it was indeed tragic that a four-engine bomber like this was shot down over England where no German four-engine aircraft were known to operate. When the sum is calculated, the Turbinlite experiment record is decidedly in the negative side.

The newer centrimetric airborne radars that were being developed in 1942 spelled the end of the ineffectual Turbinlite system. New two-seat and powerful night fighters like the Beaufighter and Mosquito, using more advanced radars and pilot and navigator/radar operator teams, gave a better chance of finding and destroying the enemy, because they had their own offensive machine guns and cannons.

The almost unimaginable power of the Turbinlite blinded more than just enemy aircrews. RAF commanders and planners pushed onwards with the Turbinlite hunter-killer concept despite the early and considerable lack of success by the original Turbinlite Flights. The establishment of the ten new squadrons, equipped with Hurricanes and Havocs, indicates a certain ill-founded hope that the Air Target Illumination concept would, given time and the right tactics, work. It took only four more months before it was finally clear, under the glare of the Turbinlite, that the system was a failure. In retrospect, it seems now to be considered merely a “stop gap” system, awaiting the development of better radar. But, at the time, I am sure the air crews involved were told it was the next best thing.

Dave O’Malley