The Short Sperrin was an experimental jet bomber built by the Short Brothers aircraft manufacturer in the 1950s. The Sperrin was built in response to a specification calling for the development of a new, medium to long range bomber in the 1940s, but this evolved to call for bombers with the capability of carrying a nuclear bomb during the onset of the Cold War.
Unlike designs produced by rival aerospace companies, Short pursued a more traditional fixed wing design for the Sperrin and it was initially selected by the British Air Ministry as the winning concept. However, as the aircraft reached the testing phase, the Air Ministry decided to shelve the project as rival designs caught up and provided a more advanced alternative.
The Sperrin was never used in a bombing role and instead remained as a test aircraft before being withdrawn from this role in 1958.
Origins
The origins of the Short Sperrin began in the late 1940s, when the Royal Air Force was seeking a new bomber to replace the aging Avro Lincoln. Although the Lincoln was still considered a vital part of the RAF’s bomber fleet in the aftermath of the Second World War, newer jet engine technology was becoming more commonplace.
The British Air Ministry formally released a specification proposal in August 1947 calling for the development of a new, medium bomber that could carry up to 10,000 pounds worth of ordinance and also be relatively simple to maintain in order to enable it to operate from RAF bases overseas.
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As tensions were starting to grow with the Soviet Union as part of the Cold War by this period, the specification evolved to consider Britain’s nuclear deterrent capabilities, and asked that the new bomber be capable of ferrying a nuclear warhead to an overseas target. Although Britain was a close ally of the United States, the British government wanted to maintain independence in regards to its nuclear capabilities and not be solely reliant on the American military for protection.
The Americans also held concerns about the so-called “bomber gap” between NATO and the Soviet Union, in which there were concerns that the Soviets were building long range bombers at a faster and more advanced rate than NATO powers. Although in practice the West was in the technological lead in this area, the British government also held similar concerns.
In 1948, the Air Ministry updated the specification to call for a jet powered bomber that would be equal to or more advanced than anything the Soviet Union or US had at the time. The specification also requested the design be capable of having a range of around 1,700 miles, a top speed of 580 miles per hour and a climb ceiling of 50,000 feet. Most notably, the specification demanded that the new plane be able to carry a nuclear bomb of 10,000 pounds in its bay.
The Sperrin
Three major aircraft manufacturers answered the Air Ministry’s specification call: Avro, Handley Page and Vickers. The Short Brothers company of Northern Ireland also responded with their design which would evolve into the Sperrin.
The initial three companies produced more ambitious but advanced design drafts with delta or swept wings. The designers at Short opted for a more traditional straight wing concept, drawing on previous experience from the Second World War combined with modern jet technology, and began work on the design in the late 1940s and early 1950s.
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While swept and delta wings offered for more agility, Short were focused on an existing design in the belief that this would enable a quicker production time for the aircraft.
As Short Brothers were based in Belfast, the aircraft followed the tradition of being named after important landmarks in Northern Ireland – with this new design being named after the Sperrin mountains.
The Sperrin was built using light aluminium alloys fitted to a smooth surface which the designers hoped would increase streamlining of the bomber.
Four jet engines were fitted to the aircraft, but rather than spread out across the wing they were stacked on top of each other within the same nacelle casing in the middle of each wing. The flaps and air brakes were operated hydraulically.
Power would be provided by the Rolls Royce Avon engine, making the Sperrin the first bomber design to be fitted with the Avon.
The fuselage was built in four separate stages that were fitted together, with the first stage featuring a pressurized cockpit for the crew. The lower fuselage was built to house the aircraft’s radar, which Short envisaged would be a H2S Mk.9 unit. A window was also fitted in the same section for manual sights during a bombing mission.
The undercarriage was also fitted in a tricycle formation, which was becoming more common for aircraft design of the era.
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At the end of the design process, the finished Sperrin was intended to carry a crew of five (consisting of two pilots, a spotter and bomb aimer, navigator and a radio operator). The aircraft was 102 feet in length and in keeping with the specification, had a top speed of 564 miles per hour with an average cruising speed of 500 mph. As was fairly common for jet bomber designs of that era, only the two pilots had ejector seats while the remaining crew would have to bail out using parachutes in the event of an emergency.
Notably, the Sperrin’s design enabled for the plane to carry up to 20,000 pounds worth of conventional explosive bombs or a nuclear warhead. The altitude ceiling was a little under the specification call at 45,000 feet but the aircraft did have an impressive range of over 3,860 miles, making it ideal to carry out a long range mission over Soviet territory.
The RAF were initially pleased with the design and the Air Ministry expressed a preference for it over the rival designs. The green light was given to move the aircraft into the testing phase and two full sized prototypes were produced.
However, the Air Ministry were also aware that the other three manufacturers who had answered the call were making progress with their more advanced designs. It was decided the Sperrin would be put into production as a fall back option should the other three bombers not meet their production targets or see successful proving results.
Testing
The first Sperrin completed its maiden flight on the 10th of August, 1951 with RAF test pilot Tom Brooke-Smith at the controls.
The initial feedback on the Sperrin was good, with test pilots and engineers noting that despite its size and somewhat older design, the aircraft was more than capable of flying at high speeds and altitudes. However, the timing of the project was placed in jeopardy when Vickers successfully completed and released their Valiant bomber in response to the proposal.
Although the Valiant was a more advanced design, it was only a few months behind the Sperrin’s production schedule having already completed a maiden flight earlier in May 1951.
After some deliberation, the Air Ministry opted to proceed with the Valiant over the Sperrin and formally cancelled the Sperrin project after deeming any fall back options as superfluous, but asked Short to continue with the second prototype for testing and research purposes.
The second Sperrin, fitted with a more advanced version of the Avon engine, completed its maiden flight in August 1952.
On the recommendations of the Air Ministry, the Sperrin continued to be used for experimental roles throughout the 1950s and served as an engine test bed. In 1955, the first prototype was used to test the new de Havilland Gyron turbojet engine and had them fitted in the lower part of the engine nacelle.
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During a second test of the Gyron in 1956, part of the undercarriage fell off the Sperrin prototype but the aircraft was able to make a safe landing without any injuries to the crew.
The second prototype had been produced with a fully operational bomb bay and was used in weapons trials by the British Ministry of Defense to test the shapes and aerodynamic qualities of nuclear bombs.
The Sperrin was fitted with mockups of the Blue Danube nuclear bomb and later the television camera guided Blue Boar bomb built by Vickers. Although a real Blue Danube was never carried by the Sperrin, the information from the tests provided a useful template into how other bombers could cope with the weight and shape of the weapon.
The tests were also useful for concluding that the Blue Boar bomb would ultimately be an unsuccessful design.
Fate
Although the Sperrin was able to provide useful information on engine development and hypothetical transportation of a nuclear bomb to its target, both prototypes were withdrawn from experimental service once both test programs were wound down.
The RAF command ultimately pressed ahead with the Vickers Valiant, Avro Vulcan and Handley Page Victor to form Britain’s airborne nuclear deterrent force. These three bombers became known as the V Bombers and provided Britain’s nuclear defense up until ICBM missiles were perfected.
Both Sperrin units were dismantled once their experimental use was concluded. The first prototype was broken up in 1957 while the second was sent to the de Havilland plant in Hatfield where it was scrapped in 1958.
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Despite its relatively short service and not reaching its intended use as a bomber, the Sperrin was a unique design that played off of traditional formats and proved itself useful in a research role.
Specifications
- Crew: 5
- Length: 31 m (102 ft 3 in)
- Wingspan: 33 m (109 ft)
- Height: 8.7 m (28 ft 6 in)
- Max takeoff weight: 52,200 kg (115,100 lbs)
- Powerplant: 4 x Rolls-Royce Avon RA.3 turbojet engines
- Maximum speed: 567 mph (913 km/h)
- Range: 3,759 mi (6,050 km)
- Service ceiling: 13,725 m (45,000 ft)
