Air Defense of the Giuk Gap: F-15 Eagle Territory

The Greenland, Iceland and United Kingdom air defense sector, better known as the Giuk Gap, was routinely utilized by the USSR’s long range heavy bombers and maritime reconnaissance platforms as a transit point towards the Atlantic Ocean. The pattern started when the Soviet Union decided to deployed their bombers or recon aircraft from bases located at Archangel and Murmansk. After departing the USSR’s airspace, the planes would stream down to the North Cape in Norway towards the Gap which was used as a doorway to the vast Atlantic. Most of the Soviet missions were destined to probe United States’ air defense along the North Atlantic and in the Caribbean where Cuba, the USSR’s most important satellite state outside continental Europe, rested. Such was the perceived threat from the Soviet incursions that it became a priority for the North Atlantic Treaty Organization (NATO) to demonstrate that the strategic Giuk passage would be monitored at all times. The best way to achieve this was to intercept and shadow all Soviet transits in and from the Gap.

The best opportunity to do this was when a formation flew through the relatively narrow space that separates Greenland and Great Britain. In the middle of this ‘gap’ lay the small country of Iceland. Iceland became a full time member of NATO in 1949, but due to its complete lack of military resources and the threat of Soviet air power, the country’s leaders officially agreed on May 5th 1951 to house what would become NATO’s most important North Atlantic base outside the UK, Keflavik. The new facility immediately became the home of the 57th Fighter Interceptor Squadron (FIS) or the ‘Black Knights’, in the fall of 1954. At first, the 1951 agreement called for the FIS to take direct action only if the country’s territory was penetrated but things changed a decade later when Fidel Castro’s Cuba became a communist nation. From that moment on, Soviet aircraft utilized more frequently the Gap in order to make calls to Cuban airbases and airports in an attempt to probe deeper inside the US eastern seaboard defensive area. To meet this threat, the US Air Force equipped the 57th with advanced fighter aircraft. In 1962 the FIS was augmented by the amazing F-102. In 1973, the big F-4C Phantom replaced the 102 as the force mainstay. A new Phantom, the F-4E, was incorporated to the 57th in the summer of 1978.

By 1984, the USSR had amassed a considerable submarine launched ballistic missile capability which complemented their already powerful ICBM force. The vast majority of the Soviet SSNB submarines, known as ‘boomers’, were based at Archangel and Murmansk. Their pre-launch stations were usually in the White Sea sector. Because of this, the US Navy devoted a large portion of its SSN submarines or ‘hunter killers’ to locate and then follow the movement of all Soviet SSNB boomers in the White Sea. To perform this task, US SSNs ran through the Giuk Gap en route to their patrol areas. To counteract the Americans, the Soviet navy began a pattern of deploying an ever increasing numbers of modified Bears, called Bear F, in an effort to track the US SSNs boats before they entered the Sea.

In another countermove, the US assigned its best fighter jet, the impressive F-15C/Ds to the 57th FIS. In November 1985, the first of twelve F-15C/Ds arrived at Keflavik. The Eagles stationed at the Iceland base were different from its North American counterparts. They were fitted with Conformal Fuel Tanks (CFT). Each CFT could add up to 9,800 extra pounds of aviation fuel. Enough fuel to extend the overall operational range of the Eagles, thus giving the aircraft of the Black Knights the ability to intercept the Bears at a longer range. More fuel also meant that the planes from the 57th could shadow its target for a much longer time than before. The CFT became an integrated part of the F-15 deployed at Keflavik.

From January 1962 to the winter of 1991, Black Knights intercepted almost 3,000 Soviet long range aircraft. The most active period was between 1985 and 1986 when Icelandic Eagles netted 340 interceptions. Nearly all Soviet inbound air traffic towards the Gap was detected and tracked by the Royal Norwegian Air Force’s air defense centers. The RNorAF, with the strategic support of USAF Boeing E-3A AWACS from the 552nd Airborne Warning and Control Wing, painted all Soviet air movement in and around the Giuk Gap during their incursions. It was relative easy to spot a Bear. Its massive Kuznetsov NK-12MV turboprop engines contra-rotating four sets of large diameter propellers made a huge radar reflection. After the RNorAF notified NATO command, the E-3 fleet was scrambled to acquire and track the inbound bogey. At the same time, the F-15s would be placed on high alert status. Well prior to the Soviet aircraft’s incursion into the Iceland Military Zone, two Eagles would be dispatched to meet the intruders. A KC-135 refueling tanker would follow half an hour later to keep the Black Knights topped off thus maintaining their ability to divert and re-engage.

Early on the Bears, which were the Soviets most visible platform at Giuk, flew a very predictable pattern flying at an altitude of 25 to 27,000 feet at a relative low cruising speed. The low altitude profile coincided with the aircraft’s primary operational goal: the proving of the outer rim of the American Defense Zone in the North Atlantic Sector. On one occasion, a night flying Bear turned up its powerful spotlight which was mounted on the empennage, in an effort to disorient an intercepting Eagle pilot. The pilot did not enjoy the sight and raced out ahead of the Bear, turning around and pointed at the huge bomber nose to nose. He proceeded to lower his gear which shined its landing light in the faces of the Bears’ pilots. The two aircraft flew at a ‘too high for comfort’ combined speed of 500 knots in a pitch black sky. It is safe bet that Bear’s pilot never attempted the maneuver again.

Such as this, there are many more stories of encounters between Soviet aircraft and Black Knights interceptors. But the fall of Red Russia in 1991 signalled the end of the Cold War. After 1991, no Bear or any other type of Russian airplane approached the Iceland Defense Zone. As for the 57th, they maintained their twelve plane strength for another three years before eight were re-assigned to US continental bases. On March 1st 1995, the Black Knights were officially disbanded as its mission was taken over by rotating Air National Guard units. The Guard maintained Keflavik alert status until 2005 when the last detachment of USAF aircraft departed Iceland. But with recent Russian flybys is not out of the realm of the possibility the Air Force will once again deploy interceptors to the remote country.

- Raul Colon

The Super Stirling

In the early part of 1941, inside the corridors of power of Royal Air Force (RAF) Bomber Command, there was a growing concern regarding the Halifax and Lancaster bomber force in contrast to the Sterling platform. The perceived disadvantages of the Sterling had many in the Command clamoring for an upgrade to the existing aircraft. This lead to the RAF to send a formal request for an enhanced Sterling, in the form of Specification B.8/41. The result of this was the project called “Super Stirling” which was based on the new Centaurus CE3Sm radial engine.

The new blue print for the Short Super Stirling, tagged project S36, began with the introduction of the Centaurus CE3Sm radial engine early in the summer of 1941. With the power plant in hand, it was time for the engineering team at Short Brothers (from 1943 forward, the company was named Short Brothers and Harland) to start developing the S36 concept. The first thing they did was redesign the whole wing structure. The baseline Stirling fuselage was extended for the installation of a larger central bomb bay intended to carry the huge and still in the developmental stages 8,000lb free fall bomb. This alone represented a major upgrade over the original Stirling bomber. In addition, six more wing-based cells were installed. Each cell could carry up to 1,000lb of ordinance.

In the autumn of 1941, the RAF’s Controller of Research and Development (CDR) Department issued a paper covering, among other things, the expected operational characteristics of the S36 design. The CRD viewed the new bomber as a “typical night bomber having high useful load at a comparatively slow, economical cruising speed (214mph at 15,000′) just six miles per hour faster than the Stirling”. Despite the uninspired report, the CDR still recommended that the project go to full production mode.

The first, true outline of the project now known as the Stirling III, which was revealed to the RAF’s top brass in July 15th 1941, offered an insight into the Short engineers’ vision. The “III” design had a powerful defensive armament system. Two .5 inch machine guns were placed in the nose of the aircraft, four additional ones in both mid upper and tail turrets. Another machine gun, a .303 inch caliber, was installed under the fuselage in an under turret mechanism. Maximum takeoff weight for the new bomber was estimated at 103,100lb. Top operational speed was 311 mph at a 20,000 service ceiling. Maximum operational ceiling was determined to be 29,300′. In August a further revision of the S36′s profile was made. But the outlines of it were the same, a similar airframe to the original bomber with an increase bomb load and extended longer fuselage. The S36 was conceived to be able to carry a powerful 23,500lb total bomb load, compare to the original Stirling’s 14,000lb capacity, for 2,300 miles.

On the 19th of November 1941, the Air Ministry issued Specification Order B.8/41 to cover the program costs and allocation of resources. Nevertheless, questions were raised regarding the new aircraft’s feasibility. The Controller General Office was skeptical of the Stirling III production success. In a report made public in the fall of 1941-42, the CRD issued some reservations about the development of the S36 as it compared with the Halifax and Lancaster platforms. Or even the much anticipated Avro Super Bomber design, still years away from presentation. Still, the CDR endorsed the project with an order of two sample aircraft on 9th of January 1942. The CRD assigned serials JR540 and JR543 to the two units. One, without a certain operational requirement, the other ready to fly once completed.

It was estimated that the first unit would take to the air in the autumn of 1943. Shorts were also encouraged to prepare a production blue print for an Initial Production Order of twenty aircraft with a possible extension of 130 units. On May 11th, the Commander in Chief of the RAF’s Bomber Command, Air Chief Marshall Sir Arthur Harris wrote that “the B.8/41 was expected to eradicate the weakness of the present Stirling force and with much bigger span wings should be a better aircraft. But the new potential given does not justify the change over, the switch will cost at least 126 Stirlings at Rochester plus a ratio of two B.8/41s for three Stirlings. The best course is to concentrate on the Hercules VI Stirling which will go a long way to improve the really weak feature, its operational ceiling at weak mixture. The Hercules VI should push this up to 19,000′ from 16,000′ which is superior to the B.8/41″. Coming from Harris, these words were gospel to the Air Ministry.

A fortnight later, Short brothers were told to cease all work on the S36 project. The Ministry estimated that by the time the S36 achieved operational status, and taking into the equation the expected increases in additional weight that usually goes into a new aircraft, the new profile of the bomb load would be insufficient to justify the losses of standard production Stirling. The decision stunned Shorts who, for a while, entertained the idea of privately continuing with the program. But on August 5th they decided to abandon the whole program. The valuable data gained during the program’s life was used on another air platform concept; the Vickers Long Range High Altitude Super Bomber.

- Raul Colon

References:
Air Power: The men, machines, and ideas that revolutionized war; from Kitty Hawk to Gulf War II, Stephen Budiansky, Penguin Books 2004
International Air Power Review, AIR Time Publishing, Volume 22, 2007

Cierva’s Autogyros

When the famous Spanish inventor, Juan de la Cierva, was only fifteen he designed and built his first glider. Three years later, in the summer of 1918, he was able to develop a three-engined aircraft. The goal of his experiments was to achieve the creation of an air platform that could sustain lift and land safely after an engine failure. With the development of helicopters still a thing more of the imagination rather than a practical concept, Cierva turned his attention to the idea of an airplane that utilized an unpowered rotor system for lift and a conventional propeller mechanism for propulsion. Does the concept sound familiar?

The term ‘autogyro’ was conceived by Cierva to describe his new aircraft idea, which featured a freewheeling main rotor providing lift for vertical flight. His idea would revolutionize the air industry thus paving the way for the full development of the helicopter. The main operational system of the autogyro was the articulated rotor hub. Its drag and flapping hinges allowed the individual rotor blades to rise and fall, and so even-out the plane’s lift. After a two year development program, Cierva’s first autogyro took to the air on a cool January morning in 1923. Called the C.4, the first unit flew a distance of 3 miles. By September 1928, Cierva’s C.81 design, powered by a 149kw (200hp) Lynx engine and based on an Avro 504 airframe, performed the always dangerous 25 mile crossing of the English Channel, bound for Paris.

Avro-built Cierva C.30P G-ACIN. (photo, via author)

After experimenting with a few ideas and systems, Cierva refined his autogyro concept into what would become the technology setter platform of C design and development: version number 19. Version 19 introduced a dedicated fuselage to the series. Prior Cierva models utilized existing aircraft fuselages. After the 19, all other versions were purpose-built. Sixty six 19s were licensed built by AV Roe and Co. Ltd. with headquarters in Manchester, England. France also got into the act. The famous Liore-et-Oliver produced twenty five units designated LeO C130. Even the German Focke-Wulf Corporation managed to built 19s (40 units are believed to have been produced by the venerable aviation company).

If version 19 was a leap forward in rotary wing development, then version 30 was the pinnacle of it. The C.30 was a two seat airplane that featured the pilot occupying the rear, open cockpit. The pilot was able to unlock and tilt the main rotor mechanism using the control column attached to the rotary head. The 30′s airframe structure was of Duralumin tubing with a fabric skin cover. The next evolution of the series, the C.40, was designed around a wooden skin cover over a metal internal frame. A seven cylinder, Armstrong Siddeley Genet Major I-a radial (139hp) engine gave power to the 40. The other main feature introduced in the 30 was folding rotor blades for easier hangar handling. It also possessed a reverse aerofoil section on the port tailplane in order to counter the anticipated rotor torque.

At the beginning, autogyro flying was deemed too dangerous for combat operations, thus not many air forces in the world were interested in Cierva’s revolutionary work. Early flying tests were plagued by accidents. In fact, the first three C designs failed to become airborne. It is worth remembering that the initial C.1, utilized a French Deperdussin fuselage that did not provide the aircraft with enough lifting area which impeded its ability to takeoff. It was number four in the series, C.4, which eventually broke that barrier and got airborne. Following the experiments of the C.1, Cierva went on to produce several other unreliable machines, including the C.4, until he designed the unit 6. With subsidies from the Spanish government, the ingenious Cierva developed the C.6 series utilizing an Avro 504K airframe. The new fuselage would give the series and its inventor a big boost with its lift-drag ratio and overall airframe performance. All other versions of the Autogyros will incorporate the same, basic layout of the 504K airframe.

By the mid 1930s, Cierva and his team were able to stabilize vertical takeoff to the point that air forces felt comfortable enough to invest heavily in the concept. Unfortunately, Juan de la Cierva died in an airline crash at Croydon in December 1936. By that time his ideas were more than accepted, it was becoming the ‘law of the land’ in rotary flying. At the time of his death, Cierva had formed his own aircraft company based in Great Britain. His design was being manufactured in England, France and Germany. The C.30 saw service in the Second World War, most of them with the British Royal Air Force (RAF). There were a commercial version of the C.30, chief among them the de Havilland’s C.24 developed in 1931, but the unit did not meet with much success. Nevertheless, the original Cierva concept would go on to become today’s helicopters platforms. Quiet the achievement for this distinguished Spanish inventor.

- Raul Colon

More information:
The Encyclopedia of Modern Military Aircraft, Editor Paul Eden, Amber Books 2007
The men, machines and ideas that revolutionized war, from Kitty Hawk to Gulf War II, Stephen Budiansky, Penguin Books 2004
Concept Machines, Carl Thomas, Ispring Group 1972