The Royal Air Force’s Avro Lancaster and Handley Page Halifax are considered by many aviation historians to be among the most capable heavy bombers of the Second World War. However, neither were the RAF’s first four-engine bomber.
Overshadowed by the Lancaster’s success was the Short S.29 Stirling, the first of the RAF’s “heavies.” Developed in the mid-1930s, it was also the only one of the three to be designed with four engines, as the Halifax and Lancaster evolved from twin-engine bombers. The “head start” also somewhat ironically resulted in the Stirling being the first to be withdrawn from frontline service.
By the end of World War II, it found new roles as a transport and glider tug, while there were even efforts to convert it to a passenger aircraft for the civilian market in the post-war years.
Short, But Heavy
In the early 1930s, the RAF remained interested in two-engine bombers. It was a matter of practicality, based on lessons learned from the “Great War” and its static trench lines. Great Britain’s prime adversary was again expected to be Germany, and few expected anything but a repeat of the former conflict. The focus on an aircraft with two large engines was meant to limit the demands on engine production and maintenance.
However, as the United States pursued the development of four smaller engines, it was discovered that they could provide a greater range. The RAF opted to explore a similar design, and the Air Ministry published Specification B.12/36, which drew submissions from Armstrong Whitworth, Supermarine, Boulton Paul, and Handley Page.
Not included was the Short Brothers plc, an aerospace company based in Belfast, Northern Ireland. Founded in 1908 in London, Short was the first to make production aeroplanes. It was later included as the company already had similar designs and possessed the ample staff and production facilities to produce such an aircraft.
Short had been building four-engine flying boats, and from that evolved two prototypes, including the S.29.
It was given the service name “Stirling” after the Scottish city of Stirling. With the clouds of war gathering on the horizon, the airplane maker was awarded a contract to produce 100 aircraft at its Rochester, England, factory. That was followed by a second order for an additional 100 bombers, built at Short & Harland’s Belfast facility.
The first production Stirling MK I, powered by four 1,595 hp (1189-kW) Hercules XI engines, was delivered on May 7, 1940. Germany launched its invasion of France and the Low Countries just four days later, and by the end of June, France had fallen.
Stirling orders subsequently were increased, and contracts to manufacture the four-engine heavy bomber were extended to more than 20 factories. However, due to the Battle of Britain from July to October 1940, production of the bomber was slow, as priority was given to fighter construction. Moreover, the destruction of the Short assembly lines in Rochester and Belfast in August 1940 further impacted production.
It was only by the end of 1941 that more than 150 were finally completed. The total production of the aircraft totaled 2,371. Yet, as the bomber entered service, its shortcomings were soon evident.
Plans to build the Stirling in Canada were canceled. As additional Halifax and Lancaster bombers entered service, the Stirling was withdrawn from service or relegated to other tasks.
Stirling Specs
The monoplane bomber was longer and taller than the bombers it would replace, but both the Halifax and Lancaster had begun as twin-engine aircraft. It was also developed from the outset with four engines, but featured a short wingspan owing to a design requirement that the bomber could be housed in the standard pre-war hangars, which had just 100-foot door openings.
Although the wing area was the chief limiting factor, resulting in poor operational altitude when fully loaded, it proved to be stable in flight and surprisingly maneuverable. It was this agility in combat that earned it the nickname “the fighter bomber.”
The Stirling could carry as much as 14,000 pounds of bombs, but it was unable to accommodate the larger bombs that the Lancaster could accept. Its seven fuel tanks in each wing provided it a combat range of 900 miles in favorable conditions.
To shorten take-offs and landings, a very tall undercarriage was fitted to the bomber to give the wings a sufficient angle of incidence to provide adequate lift. It required a skilled pilot to address the Stirling’s tendency to swing violently unless it was handled carefully. The problem was exacerbated by the fact that the undercarriage retraction motors often proved inadequate at times.
The Stirling was typically flown with a crew of seven, including two pilots, supported by a navigator/bomb aimer, front gunner/wireless operator, two additional gunners, and a flight engineer. The latter two crewmen were housed in a cabin just forward of the leading edge of the wing, directly behind the navigator station. The pilots were seated in a fully glazed flight deck positioned above those stations.
It was armed with eight .303 machine guns, including two in the nose and dorsal turrets, and four in the tail turret.
Later models, beginning with the Mk III, were equipped with the 1,635 hp (1,219-kW) Hercules VI or XVI engines. Beyond the minimal extra power, the main advantage of the improved powerplant was that the engines were easier to maintain. In addition, the Mk III was equipped with a refined dorsal turret featuring a flatter profile.
The Stirling Goes to War
As the first of the RAF’s four-engine heavy bombers to enter service, the Short Stirling equipped seven squadrons in No. 3 Group and was based at airfields in the Cambridge-Huntingdon area. No. 7 Squadron first received the bomber in August 1940. The bomber took part on its first combat operation on the night of February 10-11, 1941, when it targeted an oil storage depot in Rotterdam, Netherlands, which was under German occupation.
Official figures from the RAF indicated that the Short Stirling took part in 18,440 sorties, during which it dropped 27,821 tons of bombs and laid more than 20,000 mines. During the war, 769 of the four-engine bombers were lost.
Although the Short Stirling was a moderately successful aircraft for its time, taking part in the RAF’s early nighttime bomb raids on occupied territory, its inability to fly above 20,000 feet and its lack of adaptability with the bomb bay to carry heavier ordnance simply meant its time had passed.
Filling Other Roles
From early 1944, the RAF employed the Short Stirling either as a glider-tug or transport. Initially, the RAF Transport Command had sought to obtain either the Halifax or Lancaster aircraft for those roles. The former wasn’t produced in adequate numbers, and the latter was simply too important as the premier heavy bomber.
A pair of Mk III models served as the prototypes to highlight how the conversion could be made. Designated the Mk IV, the tug/transport retained the Mk III’s improved engines, but it saw the removal of the nose and dorsal turrets. In addition, glider-towing equipment was fitted in the rear fuselage. Interestingly, removing the turrets improved the ceiling and even the top speed.
The Stirling may not have been designed to fill such roles, but it proved to be quite effective in doing so. The bomber-turned-tug towed the Airspeed Horsa gliders to Normandy on June 6, 1944, and the aircraft was employed at Arnhem during Operation Market Garden in September of that same year. The tug was used a final time during World War II in Operation Varsity, the airborne operation that dropped 16,000 paratroopers into Germany to help establish a beachhead to cross the northern Rhine River.
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Between D-Day and VE-Day in May 1945, Stirling Mk IV aircraft were almost continuously employed to fly fuel to fighter and light bomber units of the 2nd Tactical Air Force on the Continent. In each run, the Stirling was tasked with carrying 600 Imperial gallons (720 U.S. gallons/2,728 liters) in five Imperial gallon cans!
The four-engine aircraft in service with No. 138 and No. 161 Special Duties Squadrons, which flew for the Special Operations Executive (SOE), was tasked with carrying small arms to the Resistance in occupied Europe.
A total of 321 MK IVs saw service, including 120 that had been converted from the Mk III.
The final variant of the Stirling was the Mk V, which was similar to the Mk IV, but employed solely as a cargo/transport aircraft. It could carry up to 40 troops or 20 fully equipped paratroopers. Alternatively, it could transport a dozen stretchers and another 14 seated casualties. It featured a lengthened nose that hinged open, while on the right-hand side of the rear fuselage was a portable loading ramp. As a transport aircraft, the Stirling could carry two Jeeps with trailers or a single Jeep with a field gun, trailer, and ammunition.
The Legacy of the Stirling
After the end of the Second World War, there was some consideration of using the surplus aircraft as civilian transports, but fewer than a dozen appear to have been employed in this manner by the Belgian-based Trans-Air. The Stirling was also briefly used by the Egyptian Air Force, with a handful seeing combat during the 1948 Arab Israeli War.
There are reports that a handful were captured at some point by Germany during the Second World War and pressed into service by the Luftwaffe, but the circumstances are murky.
Sadly for aviation buffs, the fact is that although 2,371 were produced, not a single one survives intact today. Efforts to recover any that crashed into the sea have been unsuccessful. The legacy of the Short Stirling is that, while it wasn’t the RAF’s most successful four-engine bomber, it was still the first.
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