Wallis and Whittle

Grand Slam combat operations

Barnes Wallis and Frank Whittle, probably the best-known British inventors of the twentieth century, worked in the air-industrial complex. Both were supported very strongly by it because they came up with new ideas which were felt to be worth trying; their revolutionary inventions were supported because they were so novel, because they promised new offensive capabilities, which promised early victory.

In the summer of 1940 Wallis hatched an incredible war-winning scheme, `a monster bomber to smash the Germans'. By mid-July 1940 he had come up with a plan for a `High Altitude Stratosphere Bomber' (soon to be called the Victory Bomber). This would be a gigantic thing, with a fully laden weight of more than 50 tons, much more than the 30-ton future Lancaster bomber. It would carry 10 tons of bombs but at nearly twice the altitude of the future Lancaster, 40,000 feet, and for a considerably longer range. Wallis claimed to his superior in Vickers that `the new machine is going to be the instrument which will enable us to bring the war to a quick conclusion'. He explained that given the altitude they would operate at, they could fly `at their leisure and in daylight'. Large numbers were unnecessary: `irreparable damage could be inflicted on the strategic communications of the German Empire by . . . ten or twenty machines within the course of a few weeks'. He was confident that a new gyroscopic bombsight would give bombing accuracies of 150 yards from 40,000 feet. Such a machine had another advantage: Britain would have `the machine and the experience to enable us to step right into the forefront of transoceanic civil aviation directly war ceases'. It could fly direct to New York in twelve hours.

Vickers put this plan for a Victory bomber forward to Lord Beaverbrook, the Minister of Aircraft Production, in November 1940: the aircraft, pressurized and built to Wallis's geodesic principle, which was successfully used in the Wellington bomber, would have six engines. A map showed that it could bomb Moscow from London. The idea was to attack coal mines, underground petrol and oil storage, oilfields and hydroelectric dams, to strike at these `sources of power' rather than humble power stations. Wallis's concept was one of `anti-civil engineering bombing', as he called it; he wanted to destroy great works. The project was taken up by the Ministry of Aircraft Production, but work was dropped in 1942.

Two crucial aspects of the scheme did live on. The first was the idea of attacking civil engineering works, in this case dams. In 1943 Lancasters carrying the `bouncing bomb' designed by Wallis destroyed, temporarily, some dams in the Ruhr region. The RAF did not bomb the repair work; nor did it repeat the use of the bouncing bomb - it was far too expensive in terms of crews lost. In fact the remaining stock of bouncing bombs was dumped in the sea at the end of the war. The second was the idea, already in play in the Victory bomber, of bombs much larger than conventional ones, which would destroy large and strong structures. Great ingenuity and resources went into developing this concept. Wallis planned that the Victory bomber should drop new 10-ton bombs, many times bigger than current ones. Wallis designed the 6-ton Tallboy and then the 10-ton Grand Slam bombs, which were dropped from 1944 and 1945 respectively, but from Lancasters. Tallboys were used with some success against great structures like U-boat pens, the Tirpitz, which was sunk in late 1944 as a result of the third attack with these bombs; the Grand Slams were used to destroy viaducts and bridges, including the Bielefeld railway viaduct. In fact the viaduct had been under continuous attack since June 1944 by US and then British airforces, the latter using Tallboys. It was damaged but was quickly repaired, and a bypass was built making the viaduct significantly less important. The bypass had to be used for years after the war, as the viaduct was destroyed in March 1945 by the first, and much celebrated, Gland Slam raid. Wallis's `bouncing bomb' was of course the subject of The Dambusters film of 1955. As told in the film, bizzarely yet influentially, Wallis battled with a bureaucracy disinclined to accept new ideas from engineers. Yet Wallis received massive support, to produce a weapon which was in the event used on only one raid, one whose results were not as great as expected.

After Wallis, perhaps the most famous wartime inventor was Frank Whittle, in British eyes the inventor of the jet engine. Whittle was an air force officer who had been sent to Cambridge to study engineering in the 1930s; like others, he was given the opportunity to stay on and he developed his idea of the jet engine. With air force support he was seconded to a private company set up to develop his ideas, and this company, with state contracts, was to carry the main but not the only early development effort. All this happened before the war: by 1939-40 the project was well under way. By 1939 plans were being made to fit it to an aircraft; by early 1940 the jet engine was on a list of `war winners' and by late 1940 was ordered into production.

There was a brief hiatus in mid-1940, but Lindemann's interest in jets was `an important factor in the remarkable renaissance in jet propulsion' in autumn 1940.14 During the war the number of jet engine projects multiplied, with the Whittle group one of many, in what was a state-orchestrated collaborative programme, involving many large firms in turbine engineering and aero-engines - essentially Metropolitan- Vickers from October 1940, De Havilland, who got an order in May 1941, Rolls-Royce from June 1941 (though they had employed a jet specialist, A. A. Griffiths, from 1939) and lastly Armstrong-Siddeley. Bristol too were involved. Yet belief in the power of the inventor meant Whittle, without question the key pioneer, was given a lot of scope despite the fact that many and in many respects more powerful players were in the game. His Power Jets company continued to be supported. The first British jet engine into service was a Rover / Rolls- Royce development of the Whittle W2, the W2B / 23, called the Welland by Rolls-Royce. The second was the Halford H-1 (later called the Goblin), designed by the piston-engine designer Major Halford for the De Havilland company. Halford was one the big three engine designers of the war alongside Roy Fedden, chief engineer at Bristol until 1942, and Ernest Hives, general manager of Rolls-Royce. The Goblin was considerably more powerful than the first Whittle engines but was, like Whittle's, a centrifugal compressor design.

A Gloster Meteor Intercepts a V-1 Flying Bomb
by Colin E. Bowley
1944- A Gloster Meteor of 616 Squadron operating from Manston in Kent intercepts a German V-1 Flying Bomb bound for London.
Shooting at a V-1 proved to be extremely dangerous. To be within range to shoot also meant being close enough to be damaged by the huge explosion and deadly flying shrapnel.
Some pilots were able to fly alongside and gently tip the wing of the V-1 to send it out of control and into the empty fields below.

The Gloster Meteor, a fighter equipped with two Wellands, went into partial service in June 1944 and was used against V-1 doodlebugs. However, it was no match for the new fighters powered by the Sabre and Centaurus engines. The De Havilland Vampire, with a single De Havilland Goblin, only came into service after the war, as did a new Meteor powered with Rolls-Royce engines. Such late deployment was not intended. Production orders had been given `off the drawing board' to the Rover car company in 1940. In early 1941 it was envisaged that British jet fighters would be operational in the winter of 1942-3. A jet engine factory at Barnoldswick in Lancashire costing £1.5m and employing 1,600 workers was ready before the engine, resulting in a serious waste of resources in 1942.

Engine development was in effect to be taken out of Whittle's hands late in the war. From 1943 it was intended to nationalize his Power Jets firm, which was supported by private interests, as indeed happened in 1944. Through a series of steps it became part of the civil service after the war. But as he became less important in the actual design, Whittle was celebrated as the inventor of the jet. In 1944 he became a public figure, garlanded with honours from the state and from engineering institutions. Though still a young man he was never to design a jet engine again. Development was now very firmly in the hands of great private firms committed to the next generation of jets. The surprising ending to this story should not obscure the level of support this RAF officer got from the ministry long before the war - remaining a career officer he was seconded to a private firm to develop his invention with government money. The authorities believed in the individual inventor; his special qualities were seen as essential to creativity.

Instruments of Darkness

THE "BERNHARD/BERNHARDINE" SYSTEM

LORENZ

A prewar, civilian radio beam navigation system adapted as a bomber aid by both the RAF and Luftwaffe. It comprised a radio signal broadcast by the airfield and received passively by approaching aircraft. It had a limited range of about 20 miles. Its main importance was to aid wartime development of the Knickebein and X-Gerät beam systems.

KNICKEBEIN

A Luftwaffe electronic navigation aid for night bombers in which two directional radio beams were broadcast to intersect over a target in Britain. The bombers followed one beam—guided by Morse dots and dashes—until it met the second, then released their bomb load. It was an advance in both range and accuracy on the prewar Lorenz blind-landing system used by civil aviation. By July 1940, the RAF developed a counter, code-named “Aspirin,” which imposed a British beam atop the German beam in a process called “bending the beam,” although the German beam was never actually “bent.” The Luftwaffe next moved to the X-Gerät system, as the “battle of the beams” continued.

ASPIRIN

The centrepiece of the British Electronic Counter Measures (ECM) effort was however ‘Aspirin’, a high power transmitter which emulated the signals from the dot modulated lobe of the Knickebein. This had the effect of confusing German pilots, who even when centred in the Knickbein beam would hear the dots emanating from the Aspirin jammer. By October 1940 the British had deployed fifteen Aspirin jammers to frustrate the Knickebein system. The stakes were high. Estimates of the accuracy of the Knickebein suggested that it was capable of putting a 300 m x 300 m box around an intended target, which when saturated with bombs from a mere 40 aircraft would put the bombs down on average 17 metres apart.

X-GERÄT

A sophisticated Luftwaffe beam navigation system. It was derived from the prewar Lorenz and early wartime Knickebein systems, which the RAF successfully countered by July 1940. X-Gerät used four beams and a bomb-release mechanical computer that was triggered by passing over the three cross beams. It was deployed by a special target-marking unit of the Luftwaffe, which then dropped flares and incendiaries to mark the target for follow-on bombers.

BROMIDE

The British built the ‘Bromide’ jammer, using radar hardware, to defeat the X- Gerät system. While the Bromide equipment was being developed, KG.100 conducted no less than forty raids using X- Gerät. These raids were essentially an ‘Opeval’ to determine the limits of the system and to develop tactics. KG.100 started dropping incendiaries, a tactic to mark targets for a larger bomber force. This was the origin of the pathfinder technique later used by the RAF to obliterate German cities.

Y- GERÄT

By early 1941, the X- Gerät was losing effectiveness, along with Luftwaffe command confidence in the system. The Luftwaffe was, however, deploying a third radio bombing aid also designed by Dr Plendl, named Wotan II or Y- Gerät. Y- Gerät used a similar but automated scheme for bomber heading tracking, but used a beacon transponder arrangement for measuring range between the Y- Gerät station and the bomber. Not unlike a ‘back to front DME’, the Y- Gerät station operators could track the bomber’s position and send by radio course corrections to the pilot.

DOMINO

The Luftwaffe was less fortunate with Y-Gerät than with the previous two systems. The British requisitioned a mothballed experimental BBC television transmitter at Alexandra Palace in North London, and adapted it to rebroadcast the Y-Gerät rangefinding signal. Labelled the Domino, the Y-Gerät jammer was soon followed by a second installation at Beacon Hill near Salisbury. The RAF was effectively performing ‘range gate stealing’ jamming attacks on the Y-Gerät, to completely compromise the range measurement achieved by the Germans. The German ground station receiver would lock on to the Domino jammer instead of the Y-Gerät transponder on the bomber, and the British could then manipulate its range measurement. The Domino jammer proved effective, and in the first two weeks of March 1941 only 20 per cent of Y-Gerät raids resulted in commanded bomb releases. Three Heinkels were shot down in early May and the RAF recovered the Y-Gerät receivers. They quickly determined that the automated mechanism for measuring the bearing error in the beam was susceptible to continuous wave jamming, which crippled the bearing analyser circuit.

Time had run out for the Luftwaffe, and with the buildup for Barbarossa, the invasion of the USSR, the KampfGruppes were redeployed east and the Battle of the Beams was won by the British.

The Battle of the Beams is generally acknowledged to have been the first modern effort at electronic warfare, and was characterised by the Luftwaffe not attempting to seriously improve the jam resistance of their systems, but rather by deploying newer and more advanced systems. It remains an excellent case study of how the game of technical intelligence gathering and analysis is played, and how pivotal it is to success in modern warfare. 

Further Reading: Price A, Instruments of Darkness, Peninsula Publishing, 1987.

World War II - Churchill's Aerial Mines Project

The Harrow served in a novel operational role at the height of the German night Blitz against Britain in the winter of 1940-1941, with six Harrows equipping No. 420 Flight RAF (later to become No. 93 Squadron RAF) which used lone Harrows to tow Long Aerial Mines (LAM) into the path of enemy bombers. The LAM was an explosive charge on the end of a long cable. This unorthodox tactic was credited with the destruction of six German Bombers or 4-5, depending on the source. The experiment was however judged of poor value and the planned deployment of Douglas Havocs in the LAM role cancelled.

The Harrow served in a novel operational role at the height of the German night Blitz against Britain in the winter of 1940-1941, with six Harrows equipping No. 420 Flight RAF (later to become No. 93 Squadron RAF) which used lone Harrows to tow Long Aerial Mines (LAM) into the path of enemy bombers. The LAM was an explosive charge on the end of a long cable. This unorthodox tactic was credited with the destruction of six German Bombers or 4-5, depending on the source. The experiment was however judged of poor value and the planned deployment of Douglas Havocs in the LAM role cancelled.

No. 420 Flight formed on 29th September 1940, under the command of Flt. Lt. Burke for the purpose of experimental work in connection with the use of aerial mines in intercepting enemy planes.  These experiments were carried out with Harrow aircraft using Battle aircraft as targets.  On 26th October, the first practical experiment took place against the enemy, one aircraft being probably destroyed.

On 7th December, 1940 this Flight became No. 93 Squadron under the command of Wing Commander J.W. Homer.  It consisted of 2 Havoc Flights and 1 Wellington Flight. Experiments continued and on 23rd April 1941 the 2 Havoc Flights became operational on night interception duties using mines and the third flight was taken to form the Fighter Experimental Establishment.

Wing Commander M. B. Hamilton assumed Command on 23rd April, 1941.

During the following months the Squadron flew numerous operational sorties from Middle Wallop with detachments operating at various times from Coltishall, Hibaldston and Exeter.  There is no record of any enemy aircraft destroyed during this period and towards the end of the summer few operational sorties could be made owing to (i) the absence of enemy aircraft and (ii) the presence of friendly aircraft.

At the end of November a decision was taken to discontinue the use of aerial mines in night interception and as a result of this decision No. 93 Squadron was disbanded on 6th December, 1941.

The Long Aerial Mine (LAM)

This entered service towards the end of 1940. The background to this weapon is interesting.   Before the war, tactical papers had often exaggerated the danger to conventional fighters of attacking bomber formations. It was argued that the defensive crossfire from 20 or more bombers in close formation might inflict heavy losses on the interceptors.

Therefore it was important to devise a method of breaking-up bomber formations, to allow the fighters to pick off the bombers individually.   One proposed method was to lay a defensive minefield.   A line of such mines, positioned across the path of an enemy bomber formation, would certainly cause it to break up.

Following much experimentation, the optimum configuration for the mine was determined. The resulting weapon fitted into a cylindrical container 14in long and 7in in diameter, and weighed 141b.   After release from the aircraft the obstacle deployed. It comprised, from top to bottom: a supporting parachute, a length of shock-absorber cord, the cylindrical container, an AAD bomb, 2,000ft of piano wire and, at the bottom, a second furled parachute.

When an aircraft struck the piano wire the shock wave ran up the wire, causing a weak link to break, releasing the main supporting parachute and the cylindrical container. As the container fell away the bomb was armed and a small stabilising parachute connected to the weapon was released.   Simultaneously, the shockwave travelled down the piano wire and caused the lower parachute to open.   This took up a position behind the aircraft and pulled the bomb smartly down on the aircraft.

In the event, the Long Aerial Mine (LAM) was not ready for operations in time for the Battle of Britain.   However, in autumn 1940 Fighter Command's most difficult problem became how to counter the night raider.   The long-term answer was the Bristol Beaufighter fitted with airborne interception (AI) radar, directed on to its prey by a ground-controlled interception (GCI) precision radar.   But each of those systems was in an early state of development, and some time would elapse before they were available in quantity. In the meantime, anything even remotely likely to be effective against the night bombers was pressed into use, including the Long Aerial Mine.   German bombers attacking at night did not fly in formation.   Instead, they approached their targets at irregular intervals, following their radio beams.   At night, the mines were to serve a different purpose than that originally proposed.   Instead of being used to split up an enemy formation, a line of mines would serve as an "aircraft trap" to destroy bombers.

The minelaying task did not require an aircraft with particularly high performance. The machine selected was the obsolete Handley Page Harrow twin-engined bomber. Fully laden, its maximum speed was 170 m.p.h. at 20,000ft, and it took all of 46 min to reach that altitude.   The Harrow was modified to carry 120 Long Aerial Mines weighing nearly 1,7001b.   For night operations the spacing between individual mines was 200ft, so the Harrow's complement would produce a curtain of danger 4½ miles long and 2,000ft deep.   The individual mines descended at about 1,000ft/min, so the curtain remained effective for about 2 min.

In September 1940 No 420 Flight formed at Middle Wallop with modified Harrows. During December the Flight was expanded into 93 Sqn and the new weapon was sent into action.   For these operations the Harrow was guided by ground radar to a release position in front of the raiders.   On the night of December 22, Fit Lt P.L. Burke laid out a line of mines in front of two enemy bombers.   Shortly afterwards one of the radar "blips" seemed suddenly to disappear from the screen, and the bomber was assessed as "probably destroyed".

One of those who flew Harrows with 93 Sqn during the Long Aerial Mine operations was Flt Lt Dennis Hayley-Bell.   He later told the writer:

"One flew alone in the Harrow, which meant that during the long climb to height and the subsequent wait for the enemy one felt rather lonely.   The clumsy Harrow was not an ideal machine to go to war in.   It was very slow and, because there was no heating and the cockpit sealing was often poor, very cold at high altitude.   When the radar controller saw a likely-looking enemy bomber coming in my direction, he would direct me on to an intercept heading to one side and about 1,000ft above the intended victim. At the critical moment I would receive the order to turn sharp left or right, so as to bring me across the path of the victim.   Then I would start the 'Mickey Mouse' the clockwork unit which released the bombs - at the correct time intervals (just under 1 sec) so they were strung out at 200ft intervals behind the aircraft.   It took about 1½min to drop one's complement of mines, then it was just a question of waiting.   If one was very lucky, one might see a flash to indicate that an enemy aircraft had hit one of the wires and dragged down the bomb.   But usually there was nothing to be seen.   The mines were always released some way out to sea, because any coming down on land might cause damage.   During one of the early operations the ground controller failed to make sufficient allowance for the wind, with the result that several mines landed near Bournemouth and the long wires shorted out overhead power lines in the area. Fortunately everyone blamed the resultant power cuts on the Germans, so we escaped any awkward questions."

Hayley-Bell's only successful mining operation was on the evening of March 13, 1941, as German bombers came across the coast to attack Liverpool, Hull and Glasgow. After taking off from Middle Wallop in a Harrow, he climbed to 17,000ft.   Directed by the radar station at Sopley, near Christchurch, he was positioned about four miles ahead of and 3,000ft above an incoming bomber.   At a point 12 miles off the coast near Swanage he was ordered to begin releasing the mines.   After a short wait he saw a small explosion below him, followed by a much larger detonation, powerful enough to shake the Harrow.   Radar operators on the ground observed that the intended victim had missed the minefield, but it appeared that another bomber in the area had picked up a mine.   Hayley-Bell was credited with one enemy aircraft destroyed.

Between March 11 and July 29, 1941, 93 Sqn flew a total of 112 minelaying sorties, and in the course of these its aircraft attempted 59 interceptions.   Of those, only 16 were sufficiently promising to warrant the laying of a minefield.   The outcome was one enemy bomber (Hayley-Bell's) claimed "destroyed" and three more "probably destroyed".

During the summer of 1941 the German night raids tapered off, and by then the Beaufighter was in service in useful numbers.   Compared with that, the Long Aerial Mine gave only a very low probability of a kill, and operations with the weapon ceased in October 1941.