Tag Archives: Bomber

Official classification tag

Boulton Paul P.75 Overstrand

United Kingdom (1933)

Medium Bomber – 28 Built

A flight of five No.101 Squadron Overstrands. (Boulton Paul Aircraft Since 1915)

The Boulton Paul P.75 Overstrand was a two-engined biplane that became the RAF’s mainstay bomber aircraft in the early to mid 1930s. The Overstrand was an improvement upon the earlier P.29 Sidestrand biplane bombers after the type recieved several criticisms regarding the frontal gunner position being exposed to the elements on such a high speed aircraft. To amend the complaints, Boulton Paul would design a modified version of the Sidestrand that would use a fully-enclosed powered turret, which would be revolutionary for the time. To test the design, three Sidestrands would be converted into Overstrands. The Overstrand would equip No.101 squadron and 25 newly built Overstrands would be constructed. Aside from mainline service, a number were experimentally modified by Boulton Paul, such as receiving different turret arrangements and more powerful engines. By the time of the Second World War, the aircraft had become obsolete, as new monoplane bombers entered production and replaced it. The type would continually fly in limited numbers for training and auxiliary purposes, but by 1941 would be considered obsolete and grounded.

Boulton & Paul and the Sidestrand

The Boulton & Paul P.29 Sidestrand was a modern and aerodynamic aircraft of the time. But while it was fast it had several glaring flaws, the biggest being the open front turret which exposed the gunner to high speed winds and cold air. (Boulton Paul Aircraft Since 1915)

In the mid 1920s, the Boulton & Aircraft company was beset by hard times. The company was surviving off of small orders for prototype aircraft and was in a rough financial state. The company had, up to this point, focused on creating twin-engine biplane bombers, starting with the Bourges in the First World War and going to their latest of the time, the P.25 Bugle. In late 1925, their savior would be their newest twin bomber design; the P.29 Sidestrand. It was an all-metal, twin-engine biplane bomber with extensive work done into designing its aerodynamic fuselage, creating an innovative and sleek-looking aircraft for the time. Production was soon ordered and 18 were built. This new bomber would populate the No.101 squadron, the only bomber squadron the RAF was operating at the time. Despite its success, a problem began to arise with the forward gunners of the aircraft. The Sidestrand, thanks to its aerodynamic design and powerful Bristol Jupiter engines, was able to achieve a top speed of 140 mph (225 km/h). While this speed made the twin engine bomber quite a fast aircraft for the time, this luxury was not so appreciated by the front gunners of the aircraft, who had no means of protection against the strong slipstream in their open cockpits. The strong winds made aiming the Lewis gun difficult, as it was blown around, and even reports of the propellers being hit by drum magazines thrown from the position were growing to be common. This was not to mention the extreme cold the gunner had to endure as well. Frozen fingers were another common complaint from Sidestrand gunners. While the Sidestrands began to take to the air (and torment their front gunners), Boulton & Paul set to procure more production orders of the type over the 18 that were built, but no further production was ordered, mostly due to the worldwide recession. In the early 1930s, many current fighters of the time were experiencing the same slipstream issues as the Sidestrand was. The Air Ministry put out an order on December 28th, 1932 to seek design reworks that would fix this now commonplace issue with the Sidestrand. While many of the other aircraft would seek simple means, the issue with the gunner position on the Sidestrand was more complex and would require more work put into redesigning the aircraft. Ultimately, Boulton & Paul would decide the answer was a completely covered turret. The company had been working on such a design with their P.70 aircraft concept.

The P.70 was a concept aircraft that was based off the P.64 mailplane and used components of the Sidestrand. While it was never built, it had an innovative enclosed nose turret that the Overstrand would use. (Boulton Paul Aircraft Since 1915)

The P.70 was a twin-engine biplane bomber design based on their earlier P.64 mailplane and incorporated aspects of the Sidestrand. In the nose of the P.70 was a fully enclosed, cylindrical turret that was fully powered via compressed air. The turret would have a single gun mounted that elevated and depressed down a vertical split in the design. It would also have 360 degrees of rotation as long as the gun was elevated 70 degrees to allow it to lift over the nose of the aircraft. Ultimately, the P.70 was not selected for the competition it took part in, but the innovative turret design was chosen to be used on the reworked Sidestrand. In addition to making the front gunner more comfortable, other additions were made for the rest of the crew. The rear gunner had a new windshield installed behind his back to protect him from the fast winds, and the pilot now sat in a fully enclosed cockpit. Even further, the aircraft would implement an onboard heating system, taking off excess heat from the engine intakes. Other planned changes to the design were the wings being swept at the outer edges to compensate for the weight of the front turret, and structurally integrity was also improved in the hull of the aircraft to allow for a bigger bomb load. With the improved design finalized, it was chosen that the first aircraft to test this new design, at this point called the Sidestrand V, would be created by modifying a Sidestrand III; J9186. The order for the creation of the prototype would be 29/33.

The mockup of the powered turret design. (Boulton Paul Aircraft)

Design

The Boulton Paul P.75 Overstrand was a twin-engined biplane bomber designed to improve the performance and crew comfort of the Boulton Paul P.29 Sidestrand. The airframe of the aircraft was of all-metal construction. The fuselage had a length of 46ft 11in (14.3 m). The wings of the aircraft were all-metal, 3-bay biplane wings. The wings themselves had an additional outer edge sweep to them, a design choice not found on the Sidestrand. This was to counter the increased weight of the nose due to the powered turret. The aircraft would have a wingspan of 71ft 11 in (29.2 m). Both the upper and lower wings would be built with ailerons. Mounted between the wings were two 580 hp Pegasus II.M.3 engines connected to two 4-bladed metal propellers. The engines were housed in nacelles that also carried a 17 gallon fuel tank, priming pumps, hand-stating magnetos and a gas starter. The very first Overstrand, which was converted from a Sidestrand, was equipped with 555 hp Pegasus I.M.3 engines. Covering the engine cowlings were 9-sided Townend rings. These assisted with improving the airflow of radial engines, reducing drag and increasing the overall speed of the aircraft. Connected to the engine nacelles on each side were the main connectors for the landing gear, which were each supported by struts. The Overstrand had large, rubber wheels that were bigger than those on the Sidestrand. The cockpit was located in front of where the wings connected to the main body. The cockpit itself was fully-enclosed with a sliding hood, a feature not present on the Sidestrand. The cockpit was glazed with anti-glare perspex. For the pilot, an autopilot was equipped, a feature also found in the Sidestrand. This was located directly behind the pilot’s seat. Behind the cockpit were two gunner positions near the middle of the airframe, one ventral and one dorsal. The dorsal firing position had a windshield installed to protect the gunner from the high speeds the aircraft would encounter. The ventral position would not have to deal with the rough winds due to the way it was positioned within the fuselage. The ventral gunner would also operate several pieces of equipment, including an F.8 camera, and a wireless set consisting of a T.1083 wireless transmitter, a R.1082 wireless receiver and a T.R.11 wireless transmitter/receiver. On the converted Sidestrands, they would continue to use the T.73 transmitter and R.74 receiver they came standard equipped with. Extra ammo magazines were availablefor all gunners. For crew communication, there was a telephone system installed that connected each of the crew members. For crew comfort, a heating system was equipped in the interior of the aircraft. Each crew member was able to appreciate the benefits of this system, no matter where they were located. Heat was siphoned from the Townend rings and engine cowlings through a series of ducts into the interior of the aircraft. Care was taken to make sure these ducts were clear of objects or debris when the system was activated, otherwise they would be forcefully ejected from the vents. At the tail end of the aircraft was a 9 inch by 5 inch tail-wheel, which replaced the landing skid of the Sidestrand. The vertical and horizontal stabilizers remained largely the same as how they were on the Sidestrand, but the rudder of the aircraft was lengthened. The Overstand also retained a rudder extension that was present on the Sidestrand. The horizontal stabilizers were supported by two struts on each side that connected to the fuselage.

A view of the prototype’s nose. On later models, the turret would be widened for increased crew comfort. (Boulton Paul Aircraft Since 1915)

The most innovative technical feature of the Overstrand was the powered turret at the nose of the aircraft. The turret design was created by H A Hughes, head of Armaments Section for Boulton & Paul. The design itself was originally part of the P.70 aircraft design, but with that project being canceled, the turret was reused on the Overstrand. The turret was cylindrical in shape, with the top and bottom being rounded. The majority of the turret was covered in Perspex to allow optimal viewing for the gunner, with the rest of the turret and frame being made of metal. The powered aspect of the turret came from pneumatic power from compressed air that was held in bottles. Each bottle was held at 200 Ib/sq and fed into the turret by an engine-powered air compressor at 40 Ib/sq. These bottles were rechargeable via the compressor and, at their full, could allow a total of 20 complete rotations of the turret before being exhausted. The turret itself was capable of 240 degrees of rotation with the gun pointing forward, and a complete 360 degrees if the gun was raised by 70 degrees. The turret was held on ball-bearings with brackets connected to the bottom and top longerons of the airframe. The top longerons in particular ended in a circular design that allowed rollers to rotate. The air was fed into the base of the turret, which was the main mechanism that rotated the turret. The armament of the turret was a single .303 Lewis machine gun, mounted to a mechanism that the gunner would use. The gun would protrude from a vertical slit at the front of the turret that allowed it to elevate. To protect this slit, a zip fastener canvas was put in place, but this was only found on the prototype Overstrand and was quickly replaced by a simple canvas strip held in place by clips. While the horizontal movement of the turret was done via pneumatic power, elevating the gun was manual. To assist the gunner in this regard, his seat and the gun mount remained balanced with one another and would raise and lower with the gun. Turning the turret was done via applying pressure to plungers on each side of the gun. To prevent the gunner from damaging the aircraft or turret, if rotated with the gun lowered more than 70 degrees to the rear, it would release the pressure from the plunger and stop the turret before the barrel could hit the body. The seat could also be adjusted manually by the gunner. For emergencies, the top dome of the turret could be removed to allow the gunner to exit. The top was held onto the turret via 3 pins, which were locked via pins with finger rings. Removing these three and pushing the top off allowed the gunner to escape. At the rear of the turret was a door that could be opened to enter the airframe of the aircraft. In addition to holding the gunner, the turret also served as the bombardier’s position. The bottom of the turret was heavily glazed to allow downwards visibility. Bomb controls were located to the left of the gun and were also duplicated in the cockpit for the pilot. The bomb sight could not be used in normal use and was stowed away. For bombing, the turret was locked forward into position and the gun moved so the bomb sight could be used.

Front and interior views of the powered turret. (Boulton Paul Aircraft Since 1915)

Aside from the frontal turret, there were two other gunner positions on the aircraft’s rear; one ventral and one dorsal. Both would use the same .303 Lewis gun as the main turret. Many improvements were done over the basic Sidestrand to allow the Overstrand to carry much more weight, including an enlarged bomb load of 1500 Ibs. Two 500 Ibs bombs could be carried internall,y with two additional 250 Ibs bombs on external racks on the fuselage, Additional racks could be installed at the front and rear of the fuselage, each carrying either 4 20 Ibs bombs or 2 20 Ibs bombs and two flares.

The Overstrand Takes Flight

A side view of the completed prototype J9186. This aircraft was converted from a Sidestrand III. (Boulton Paul Aircraft)

The modifications to Sidestrand J1896 would be completed around August of 1933. On its maiden flight, the aircraft would seemingly catch fire, as smoke poured from one of the inner wings. The craft would land immediately, the culprit being found to be caused by fresh varnish on the heating system ducts. Despite this incident happening on the first flight, testing continued on the aircraft. The early days of testing the aircraft yielded two incidents which could be considered quite humorous. After a test flight not long after the first, J1896 would have one of its wheels fall into a hole on the airfield, causing the aircraft to fall forward. One of the propellers would be destroyed and the nose turret would hit the ground. The current occupant of the turret was a member of the armaments section, someone who personally helped with the creation of the turret itself. When the turret dug into the ground, he began to panic and called out for help from the ground crew as he attempted to escape the turret. Due to his panicked state, he had forgotten how to operate the emergency pins that held the top of the turret on. The ground crew found his situation ironic, one of the men who had helped create the turret had forgotten how to operate it in his panicked state. He was in no danger whatsoever and the crew eventually helped the man out. Sometime later, the Air Ministry was intrigued in seeing the progress of the innovative powered turret system and thus sent an official to inspect it. The official was allowed to enter the cockpit to try out the new device. While trying the controls, he accidentally pushed on one of the plungers and began spinning. The gun itself had also been raised over 70 degrees, allowing a full 360 degrees of rotation. In a vain attempt to stop, the official leaned against the gun, and unknowingly onto the plunger; making the turret spin continuously against the intentions of the man. Humored by the situation, the design team that was showcasing the turret simply let him exhaust the air supply and finally let him out once the turret stopped spinning. The Overstrand would make its first debut to the public in late 1933, where it was part of the “Parade and Fly Past of Experimental Types” at the Hendon Air Display. On February 22nd, 1934, the prototype flew to be tested firsthand with the 101 squadron at Andover, who had been operating the Sidestrand up to this point. The main goal was to receive feedback on the changes to the Sidestrand’s design by its would-be operators, if the new additions were at all effective in increasing crew comfort. Aerial tests began and the crews liked the new design for a number of reasons, but they also had their criticisms. Being February, the heating system was very appreciated by the crews. Thanks to its Pegasus engines, the aircraft could attain a top speed of 153 mph (246.2 km/h) while still being as maneuverable as its predecessor. Despite all of this praise, pilots noted that the aircraft felt sluggish on the controls longitudinally and that the engines caused excessive vibrations. Gunners enjoyed not being subjected to harsh winds in the newly enclosed turret, but many felt it was currently too claustrophobic. With the necessary information received, the prototype would leave Andover and return on March 19th. Revisions began immediately to fix the criticisms of the design. A second Sidestrand was converted into this new design (J9770), and the new revisions were input into the modifications of this aircraft. The turret was widened to give the gunner’s more space. The zip-fastened canvas that protected the open slit of the turret was removed in favor of a simple canvas strip that was held on by strips. To accommodate the widened turret, the fuselage nose was widened to a slight degree. Changes were done to improve the autopilot, elevators, and fins to fix the vibration issues. The two-bladed propellers of the Sidestrand were replaced with four-bladed metal ones. Work was also done to make it easier to work on the engine’s compressors. The engines were replaced by the newer Pegasus II.M3 to increase performance and all would be equipped with this engine after this point. By this point in development, the aircraft design would receive a new official name, the Overstrand, named after a town near the city of Sidestrand, the namesake of its base design. Work began on converting two more Sidestrands (J9179 and J9185) into Overstrands not long after the second was completed. Further testing of the types revealed that the aircraft was still having issues with engine vibration. This would plague the converted Sidestrands but was noticeably more tame on the later production versions.

A side view of J9770. This was the 2nd converted Sidestrand and would evenutally be equipped with Pegasus IV engines. (https://www . destinationsjourney . com/)

While Boulton & Paul was in the midst of developing their new bomber, financial issues finally caught up to the company. With the failure to procure production contracts on several aircraft in the past and the Sidestrand itself not performing as well as had previously hoped, Boulton & Paul made the decision that of their four divisions of the company, the Aircraft Division had been the weakest. The Aircraft Division was completely sold off to a financial group, Electric and General Industries Trust Ltd, who would reformat the division into its own dedicated company that would be simply named Boulton Paul Ltd. Despite this drastic change happening with the development team, Boulton Paul would continue their work on the Overstrand starting on June 30th, 1934.

With the early success of the converted Sidestrands, the RAF put out an order (Specification 23/24) to Boulton Paul, which requisitioned the production of 19 newly-built Overstrands to begin replacing the Sidestrands in service.

In Service

A production Overstrand with a Sidestrand in the background. (Boulton Paul Aircraft Since 1915)

On January 24th, 1935, the very first Overstrand would enter service with the 101st Squadron. The squadron itself was already quite familiar with the design, thanks to the testing done the year before, as well as an Overstrand being flown by No.101 squadron members at the 1934 Hendon Air Display. Here, the Overstrand would participate in a mock dogfight against 3 Bristol Bulldog fighters (This display and the rest of the air show can be viewed at the Imperial War Museum’s website, found here.). The plan was to introduce the Overstrand slowly into the squadron, at first forming a third C flight and eventually replacing the Sidestrands in A and B flights. In late May, the Overstrands participated in a bombing demonstration to officials and students of the Imperial Defense College. The target was 200 yards by 300 yards and was meant to represent a bridge. All three bombing runs hit the target and impressed the students with their accuracy. Many however were not so impressed, as the demonstration did not represent accurate combat conditions the bombers would face in battle against a target that would no doubt be defended. Further showcasing of the new bomber continued as on July 6th, No.101 would fly to Mildenhall for the King’s Jubilee Air Review. While there, King George VI would personally inspect Overstrand J9185, and he was particularly interested in the powered turret.

With the necessary modifications made to the designs from actual criticisms of the prototype, the Overstrand and its many accommodations made the aircraft very well liked by the crews who flew them. The Overstrand was a comfortable aircraft to be in, but was also a well performing aircraft no less. At the start of its service, bomb aiming accuracy went up from only 15% accuracy to 85% thanks to the well thought out turret design which factored in bomb-aiming equipment. On top of bomb-aiming, the No.101 Squadron won the Sassoon Trophy of 1935 for photo-reconnaissance with a score of 89.5% accuracy. Gunner accuracy is also noted as having improved considerably thanks to the turret design.

Starting in September, newly produced Overstrands would begin entering service with the No.101 squadron. The first accident with an Overstrand occurred on September 9th, when J9185 crashed at the North Coates Range. Despite this accident, newly built Overstrands would continue to enter service through January of 1936. Before the year would close, an order for five more Overstrands (K8173-K8177) was placed, to serve as replacements in the event any were lost. This would bring aircraft production up to a total of 28 aircraft. While most of the Overstrands would be delivered to the No.101 squadron, K4552 would be sent to the Air Armament School at East-Church, where it would serve as a training aircraft for recruits to become familiar with the type and turret. 1936 was a largely uneventful year for the Sidestrand aside from 3 separate accidents. J9197 would lose an engine shortly after takeoff, K4556 would be forced down in a bog and K4562 would have its brakes seize up on landing.

The aftermath of the crash of K4556. (Boulton Paul Aircraft)

In January of 1937, the RAF began expanding its forces, and creating new squadrons. The No.144 Squadron was formed in support of No.101 and would borrow four Overstrands until new aircraft were made available. The Overstrands would serve for only a month until new Bristol Blenheim bombers could be supplied, after which the Overstrands were returned. Also in January, K4564 would crash while flying in thick fog from Midenhall to Bicester. Unfortunately, the aircraft would be destroyed and the crew was killed. Another aircraft would crash in June. A notice was put out to modify all Overstrands by reinforcing the nose to reduce vibration. Overstrands would once again appear at the Hendon Air Display, however, this would be the last year it was held. An Overstrand would perform a mid-air refuel with a Vickers Viriginia and yet again a mock dog fight would be held, this time an Overstrand would go against three Hawker Demon fighters.

The modified nose of K1785 with the de Buysson turret. (Boulton Paul Defiant: A Technical Guide)

In 1935, Boulton Paul purchased the rights to build the de Buysson electric turret from the Societe d’Applications des Machines Motrices (SAMM) in France. De Buysson was an engineer in the organization and had designed a four-gun electrically powered turret for use on aircraft. The French government was not interested in pursuing it, but de Buysson had caught wind of Boulton Paul’s work on turrets with the Overstrand. SAMM approached the company with their turret design and John North, lead aircraft designer at Boulton Paul, found their turret design superior and purchased the rights to its patent. In 1937, Overstrand K8175, one of the reserve aircraft, was experimentally modified with a de Buysson turret. The turret heavily increased the firepower of the Overstrand from a single Lewis gun to four Barne guns in the nose. Despite the increase in firepower, K8175 would be the only Overstrand to be equipped with this turret. The de Buysson turret would serve as the basis for the turret used in the developing P.82 turret fighter, which would be soon to be renamed the Defiant. Another Overstrand, K8176, would have its turret heavily modified to house a 20mm Hispano cannon. The nose of this aircraft had to be changed drastically to equip this weapon, and the turret was now built into the fuselage. The weapon itself was now on a mount that rotated and most of the glazing of the nose was removed, while what was necessary for bomb-aiming remained.

The modified nose of K1786 with its 20mm Hispano cannon. (Boulton Paul Aircraft Since 1915)

The P.80 Superstrand: A Bomber Behind the Times

Aside from the various modifications done to the Overstrand, there are two known variants that were proposed:

Early in development, Boulton Paul pitched an idea of a variant of an Overstrand that would be converted for coastal reconnaissance, designated P.77. While this idea was pitched, it was found to be largely unnecessary, as the Avro Anson could easily fill this role, and it was a modern monoplane design.

The P.80 Superstrand was meant to be the final evolution of the design, using Pegasus IV engines, retractable landing gear and a redesigned cockpit. While expected performance was much better than the Overstrand, the design was already outdated as it was being made, as newer and more advanced monoplane bombers were entering production, the need for further refining the type was made unnecessary. (Boulton Paul Aircraft Since 1915)

At some point during its service, the second Overstrand built (J9770) was re-equipped with much stronger Pegasus IV engines to increase performance of the aircraft. Plans were further done to modernize the design with retractable landing gear. The development continued with further refinements to the design, eventually becoming a new design entirely. The P.80 Superstrand was meant to be the final step in the bomber’s design, incorporating many modern aspects that were not found on the Overstrand. Aside from the previously mentioned Pegasus IV engines and retractable landing gear, the aircraft would also use variable-pitch propellers. The cockpit section was also redesigned, now connecting the pilot’s position with the rear dorsal gunner’s. The dorsal gunner position was also now fully enclosed. The front turret had many changes done to the design as well. Only the upper section of the turret would now be transparent, and it appears that the front section was now part of the fuselage, with accommodations in the nose for a bomb sight. It was expected these changes to the Overstrand would increase the top speed to 191 mph (307 km/h), give it a maximum ceiling of 27,500 ft and an increase bomb load. The Superstrand was never built, as the aircraft was obsolete even as it was being designed. While the Overstrand was performing well, aircraft development had continued and was now pushing towards more modern monoplane aircraft designs, the opposite of what the Superstrand was. Even Boulton Paul itself, by this point, was beginning to design monoplane bombers. The previous numeric design, the P.79, was a monoplane twin-engine bomber that, while never built, incorporated many elements found in the Overstrand but now adapted onto a more modern airframe. No further work was done on bringing the P.80 to reality.

End of the Line

Direct front view of an Overstrand. (Boulton Paul Aircraft Since 1915)

By 1938, the Overstrand was beginning to show its age. Modern bombers, like the Bristol Blenheim and even larger aircraft, such as the Vickers Wellington, had already, or were soon to enter production and replace the biplanes that remained in service. The Overstrand was no exception. On August 27th, No.101 squadron began gradually replacing their Overstrand bombers with Blenheims. By summer of next year, the Overstrand would be completely removed from frontline service. Despite this, the aircraft still continued to fly in various training schools and serve auxiliary roles. 5 Overstrands were sent to the No.2 Air Observer School in 1938 for training. K4552 would be sent to the No.1 Air Observer school in Lincolnshire, where it would continue its training mission until it was deemed non-airworthy and repurposed to a ground instructional frame. Despite not being in the air, the airframe was still the victim of accidents and, on April 28th, 1940, would be damaged and scrapped after a Gloster Gauntlet trainer overshot and hit it. The final nail in the coffin for most Overstrands came in July, when K1873 would break up mid air, killing the crew. After this incident, all Overstrands were ordered to remain in training as ground instructional air frames only.

K8175 parked in front of the aircraft hangar at the Boulton Paul factory at Wolverhampton. (Boulton Paul Aircraft Since 1915)

Despite this order, a handful of Overstrands would continue flying as part of rather unorthodox missions. K8176 would be sent to be used by the Special Duty Flight at Christchurch. Eventually, this aircraft would be sent to the Army Cooperation Development unit. K4559 would be operated by the Balloon Development Unit at Cardington. There, the aircraft would provide a slipstream for barrage balloons and would test the fatigue of the cables to the balloons. By 1941, the aircraft type was deemed obsolete and it is believed the previously mentioned aircraft were returned to Boulton Paul for turret development. Not long after, K1876 would be involved in an accident due to bad weather. While flying to Edinburgh, the aircraft would attempt to land at Blackpool but would undershoot the runway and crash. This is known to be the last time an Overstrand flew. It is interesting to note that K1876 had just been painted with camouflage, which would make it possibly the only Overstrand that was not in the standard bare metal finish aside from the prototype. It is unlikely any Overstrands saw any combat by happenstance during their short period of operation in the Second World War.

With the type obsolete, all remaining Overstrands were scrapped. While no surviving aircraft remain to this day, a reproduction of the nose section of Overstrand K4556 was built and currently resides in the Norfolk and Suffolk Aviation Museum, in the Boulton Paul Hangar.

 

Conclusion

The reproduction of the nose of an Overstrand at the Norfolk and Suffolk Aviation Musuem. (https://www . aviationmuseum . net/index . html)

Ultimately, the reason the Boulton Paul Overstrand existed was to improve the pre-existing Sidestrand’s nose gunner position and create a faster platform, which it would successfully accomplish with its reworks. The Overstrand served for only a few years before more advanced aircraft would replace it, but in that time it became a well respected aircraft that was liked by its crews for the various comforts incorporated into the design and which increased the performance.

The Overstrand was a very interesting aircraft, as it seems to be in an area between eras. On one hand, it represents the last of the biplane bombers that can trace their lineage back to the First World War for Britain and for Boulton & Paul. But on the other hand, it had features that were soon to become commonplace. The powered turret design was a game-changer not only for British aviation, but the company that built it as well. Boulton Paul, under H.A.Hughes, would become one of the most prolific turret designers for British aviation in the Second World War, not only designing turrets for use on other bombers, but also with their own upcoming turret fighter design, the Defiant.

Variants

 

  • Sidestrand Mk V -The name given to the design at the start of its development.
  • Prototype Overstrand (J9186) – The very first Overstrand was a converted Sidestrand. This had a smaller turret, two-bladed propellers and a narrower nose.
  • Converted Sidestrands (J9770, J9179, J9185)– The next three Overstrands built were modified from existing Sidestrands. However, these would be further improved over the prototype by having their turrets widened, four-bladed propellers installed and a wider nose to accommodate the bigger turret.
  • Boulton Paul P.75 Overstrand – Production version. 24 built in total.
  • Boulton Paul P.77 – Variant of the Overstrand redesigned for coastal reconnaissance. None were built.
  • Boulton Paul P.80 Superstrand – The final design of the “Strand” family, the P.80 Superstrand was drawn up in the mid 1930s as to further refine the Overtrand’s design with more modern components, including retractable landing gear, Pegasus IV engines, a reworked turret, lengthened cockpit and further streamlined airframe. Due to monoplane bombers now becoming mainstream, the P.80 was seen as obsolete and none of the type were built.

Modifications

  • Overstrand K8175 – Production Overstrand that was experimentally modified to test the du Boysson 4-gun turret.
  • Overstrand K8176 – Production Overstrand that was experimentally modified to house a 20 mm Hispano cannon in its nose turret via pedestal mount.
  • Overstrand J9770 – The second converted Sidestrand, this aircraft was later experimentally modified to house Pegasus IV engines. This was done as part of the development that would lead to the P.80 Superstrand.

Operators

 

  • United Kingdom – The Royal Air Force would operate the Boulton Paul Overstrand from 1935 to 1941 in various squadrons. Most of these would fly operationally with the 101 squadron from 1935 to 1938. The type would also briefly serve with 114 squadron for only a month, until it would be replaced by Blenheim bombers. During WWII, the remaining Overstrands would be relegated to training duties and other special tasks, such as working with barrage balloons.

Boulton Paul P.75 Overstrand Specifications

Wingspan 71 ft 11 in / 29.2 m
Length 46 ft 1 in / 14.3 m
Height 15 ft 9 in / 4.8 m
Wing Area 979.5 ft² / 91 m²
Engine 2x 580 hp ( 426 kW ) Pegasus II.M.3 9-cylinder radial engines
Propeller 2x 4-blade metal propellers
Weights
Empty 8004 lbs / 3630.6 kg
Loaded 11392 lbs / 5167.3 kg
Climb Rate
Time to 6500 ft / 1981 m 5 minutes 24 seconds
Maximum Speed 153 mph / 246.2 km/h at 6,500 ft / 1981 m
Range 545 mi / 877 km
Maximum Service Ceiling 21,300 ft / 6490 m
Crew Crew of 4

1x Pilot

3x Gunners (2 would also serve as the Bombardier and Radioman)

Armament
  • 1x .303 Lewis gun in powered nose turret
  • 1x .303 Lewis gun in dorsal gunner position
  • 1x .303 Lewis gun in ventral turret position
  • 1,500 Ib (680.4 kg) bomb load (2x 500 Ib and 2x 250Ib bombs)

Credits

  • Article written by Medicman11
  • Edited by  Henry H. and Stan L.
  • Ported by Henry H.
  • Illustrated by Esteban P.

Illustrations

 

Overstrand J9186: The first Overstrand built, converted from a Sidestrand
Overstrand K4546: A production Sidestrand that was operated by the No.101 Squadron in their C Flight.
Overstrand K1785: A later Overstrand that was experimentally modified with a quad-gun de Buysson turret for testing

Sources

Boulton Paul Aircraft. Chalford, 1996.

Brew, Alec. Boulton Paul Aircraft since 1915. Fonthill Media, 2020.

Mason, Francis K. The British Bomber since 1914. Naval Inst. Press, 1994.

Yakovlev Yak-4

USSR flag USSR (1939)
Light Bomber – 90 to 100 Built

The Yak-4. [Wiki]
Following the failure of the Yak-2, Yakovlev attempted to salvage the project. One of the attempts that saw limited production was the Yak-4. While it would be powered by a somewhat stronger engine, it too would prove to be a failure and only some 100 aircraft would be built by 1941.

The Yak-2 Failure

While the Yak-2 prototype initially had excellent flying characteristics, once it was actually fully equipped with its military equipment, its performance dropped dangerously. A large number of issues, like overheating, poor flight stability, and problems with its hydraulics, were also noted during the development phase. Despite this, some 100 aircraft would be built and some were even issued for operational use.

Yak-2 side view. [Gordon & Khazanov, Soviet Combat Aircraft]
One of the many weak points of the Yak-2 was its problematic Klimov M-103 engine. The Soviet designers decided to replace this with the more powerfulr M-105 engine. Two basic designs emerged, one for a dive bomber and one for a short-range bomber. During its first test flight, the dive bomber variant proved to be so disappointing that the project was canceled. The bomber version, however, showed to be somewhat promising and the green light for its development was given.

Development History

The development of the BB-22bis (also known as Izdeliye 70bis) prototype was given to Factory No.1, and the Yak-4 designation was officially adopted only in December 1940. Engineers at Factory No. 1 started to build the prototype in early 1940 and it was completed by March the same year. This was not a new aircraft, but a modified Yak-2,serial number 1002) . That same month, Factory No.1 was instructed to produce additional prototypes for testing the aircraft’s performance by the Army, which had to be completed by the start of July 1940. The Army requested a maximum speed of 590 km/h (366 mph) at 5,000 m (16.400 ft)be , an operational range of 1,200 km (745 miles), and a service ceiling of 11,000 m (36,090 ft).

The modified Yak-2 (serial number 1002) aircraft that served as the base for the BB-22bis prototype. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev ]
Following the completion of the first prototype, a series of test flights were carried out. During one of the test flights, carried out on the 12th May, a maximum speed of 574 km/h (356 mph) was achieved. On 23rd May, however, there was an accident and the pilot was forced to crash land at a nearby airfield, damaging two other bombers and the prototype’s wing in the process. Given the extensive damage to the aircraft’s wing, the prototype had to be written off. Due to this and delays in production, the first two trial aircraft could not be completed before the end of 1940. Interestingly enough, these were actually produced by the Moscow Aircraft Factory No.81, which started the production of the Yak-4 during October and November 1940. At that time, the type had not yet received official approval from the Soviet Army.

The damage suffered by the first prototype during its hard landing was so severe that it had to be scrapped. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]

The two trial aircraft were given to the Army for testing on 10th December 1940. These tests were held at the end of January 1941. The results were once again disappointing, as these aircraft had worse performance than the prototype. With the added weight of equipment and fuel, the maximum speed was reduced from 574 km/h (357 mph) to 535 km/h (332 mph). The cockpit was described as being too cramped, and with the full bomb load, the plane proved to be difficult to control even by experienced pilots. The commission that examined the two aircraft insisted that the Yak-4 should not be accepted for service. In late February 1941, the Director of Factory No.81 gave a report to the Soviet People’s Commissar of the Aircraft Industry, A. Shakhoorin, that the production of the Yak-4 was to be stopped and replaced with the Yak-3. Interestingly enough, while the Yak-2 was developed by Alexander Sergeyevich Yakovlev, he did not direct the design process of the Yak-4.

Technical Characteristics

The Yak-4 was an overall copy of its predecessor, the Yak-2, but there were still some differences. The most obvious change was the introduction of new engines. The older M-103 ,960 hp, was replaced with a stronger M-105 1050 hp engine. The installation of the two new engines also introduced a number of internal improvements to the ventilation and fuel systems. New 3.1 m (122 in) long VISh-22Ye type propellers were also used on this model. The landing gear retracted to the rear into the engine nacelles, but was not fully enclosed. These consisted of two pairs of 700×150 mm wheels.

The rear parts of the fuselage were lengthened and redesigned, and it was less bulkier than the Yak-2. The cockpit was improved in order to provide the crew with a slightly better overall view. The rear gunner received a completely new pivoting canopy. He operated the TSS-1 mount armed with two 7.62 mm (.30 caliber) ShKAS types machine guns.

Rear view of the Yak-4. [Wiki]
The maximum bomb load was increased to 900 kg (1,980 lbs). In addition, there was an option of mounting two 90 (20 gallons) or one 250 liter (54 gallons) auxiliary fuel tanks under each wing. There were six fuel tanks placed in the wings. These had a total capacity of 1,120 litres (244 gallons) of fuel.

A front view of the Yak-4 with its new and stronger M-105 engines. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]

In Combat

The Yak-4, together with the Yak-2, was allocated to the 314th and 316th Reconnaissance Regiments in the western district. Some were given to the 10th, 44th, 48th, 53rd, 136th and 225th short to medium range Bomber Regiments. The main problem for the units that operated the Yak-2 and Yak-4 was the slow delivery of these aircraft. For example, only a few pilots from the reconnaissance units had a chance to fly on these new aircraft. By 10th June 1941, only limited numbers of Yak-4s were available for service. A shipment of some 10 new aircraft was meant to arrive but did not due to the war’s outbreak.

Pilots from the 314th Reconnaissance Regiment performed several flights over the border with Germany just prior to the Invasion of the Soviet Union while flying Yak-4s. The Germans responded by sending the Bf 109E to intercept them, but they failed to do so. However, once the war started, the German Luftwaffe destroyed many Soviet aircraft on the ground. This was also the case with the Yak-4, with the majority lost this way. Some did survive though and offered limited resistance to the Germans. By September 1941, on the Northern front, there were still fewer than 10 operational Yak-4s. To the South, there were still some 30 or so Yak-4s which were still operational by October 1941. There is no information of the use or losses of the Yak-4 after 1942. According to Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev , at least one Yak-4 was still operational and used by the 118th Reconnaissance Regiment in 1945.

Most of the Yak-4s were destroyed on the ground by the advancing Germans. [Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev]
The advancing Hungarians, who were supporting the Germans during the Invasion of the Soviet Union, managed to capture at least one Yak-4 aircraft during 1941. The use of this aircraft by them would be limited at best, due to the scarcity of spare parts and general poor performance.

Production

The production of the Yak-4 was only carried out at Factory No.81. The production lasted from November 1940 to April 1941. Around 90 to 100 aircraft would be built, with the last 22 Yak-4s being delivered for use by late April 1941.

Operators

  • Soviet Union – Operated some 90 aircraft
  • Hungary – Managed to capture at least one Yak-4 aircraft

Conclusion

Despite attempts to resolve a number of issues noted on the previous version, the Yak-4 in general failed to do so. The problem was the overall poor design of the original Yak-2 which offered little room for improvement. The inability to improve the aircraft to the satisfaction of the Soviet Air Force led to the cancelation of the Yak-4 project after only a small number of aircraft was built.

Yak-4 Specifications

Wingspans 45 ft 11 in / 14 m
Length 33 ft 4 in / 10.18 m
Wing Area 316.4 ft² / 29.4 m²
Engine Two M-105  hp engines
Empty Weight 10,050  lbs / 4,560 kg
Maximum Takeoff Weight 13,481 lbs / 6,115 kg
Climb Rate to 5 km In  6.5 minutes 
Fuel load 1,120 litres (244 gallons)
Maximum Speed  332 mph / 535 km/h
Cruising speed 284 mph  / 458 km/h
Range 460  miles / 740 km
Maximum Service Ceiling 31,824 ft / 9,700 m
Crew Pilot and the rear gunner. 
Armament
  • Two 7.92 mm (.30 caliber) machine guns 
  • 400 to 900 kg (880 to 1.980 lbs) bombs

Gallery

Illustrations by Ed Jackson

Yak-4, 118th Independent Reconnaissance Aviation Regiment, Northern Fleet, 1943
Yak-4, Riga, Latvia, June 1941
Yak-4, 314th Reconnaissance Aviation Regiment, 1941
Yak-4, Grodno, Belarus, June 1941
Yak-4 from the 314th Reconnaissance Aviation Regiment, Babruysk, Belarus, June 1941

Credits

  • Written by: Marko P.
  • Edited by: Stan L. & Henry H.
  • Illustrations by Ed Jackson

Sources

  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata SSSR, Beograd
  • B. Gunston and Y. Gordon (1977)Yakovlev Aircraft Since 1924, Putnam Aeronautical Books.
  • Y. Gordon, D, Khazanov (1999) Soviet Combat Aircraft, Midland Publishing
  • Y. Gordon, D, Khazanov and S. Komissarov (2005) OKB Yakovlev, Midland
  • G. Sarhidai, H. Punka and V. Kozlik. (1996) Hungarian Air Forces 1920-1945, Hikoki Publisher

 

Yakovlev Yak-2

USSR flag USSR (1939)
Ground attack bomber – 100 Built

The Yak-2. Source: Y. Gordon, D, Khazanov Soviet Combat Aircraft

During his career, Alexander Sergeyevich Yakovlev designed a number of successful aircraft, his most famous being his single engine fighters. But his first proper military aircraft project, the Yak-2, would be so poorly designed that it was practically useless. Nevertheless, thanks to Yakovlev’s good standing with Stalin, this aircraft would be put into production, albeit in small numbers, and would see limited action during World War Two.

The No-22 and BB-22 projects

While being involved in civil aviation, Yakovlev wished to pursue military contracts., Yakovlev actually wanted to gain a proper military contract. He estimated that the best way to do this was to impress Stalin himself. To do so, he set on designing the fastest plane in the Soviet Union. Having no previous experience in designing military aircraft, this was no easy task. Nevertheless, he soon began working on a two-engined mixed construction aircraft named simply the No.22 (but also known as the Ya-22). When the prototype was complete and flight tested it reached a maximum speed of 567 km/h (352 mph). This design would first be presented to the Soviet Spanish Civil War hero Yakov Smushkeviche, who was also the Chief of the Soviet Air Force. Yakov was highly impressed with this aircraft and informed Stalin about its performance. Stalin agreed and gave a green light for its future development.

In May of 1939, for further testing and evaluation, this prototype would be given to the Nauchno Issledovatelysii Institut (NII VVS). There, the aircraft was evaluated by a commission consisting of Chief engineer Holopov, test pilot Shevarev, and navigator Tretyakov. They managed to reach a maximum speed of 567 km/h (352 mph) without any problems. The commission also suggested that, with an improved cooling system and with new propellers, the maximum speed could be increased up to 600 km/h (372 mph).

When Yakovlev began working on the No.22, he did not seriously consider in which role it should be used. Military officials would decide the aircraft would be used as a light bomber, a use that both Yakovlev and Stalin would agree with. The plane would be renamed BB-22  (Blizhnii Bombardirovshchik, short range bomber) to fit its new role.

 

The BB-22 prototype, Source: Source: Y. Gordon, D, Khazanov Soviet Combat Aircraft

While at first glance the BB-22 showed to be capable of racing at high speeds, its use in military aviation would prove to be highly problematic. The core of this problem lay in the fact that this aircraft was designed with the main purpose of reaching the highest possible speed, with little thought for military adaptation. Very shortly, the BB-22 began showing the first signs of being an inadequate design. While being tested, it was noted that the engine was prone to overheating. During one test flight, the pilot attempted to reach 7,000 m (23,000 ft) which the designers claimed that it could reach in 8 minutes. In reality, the pilot needed more than half an hour due to constant engine overheating problems. Other issues were also noted, like the inadequate fuel system and wheel brakes.

In the meantime, Air Force officials were discussing the BB-22’s performance and if it should have been put into production. Nearly two months earlier, Yakovlev had already made first steps for the BB-22’s production without their knowledge, despite no official order being given. While military officials were still discussing the BB-22, he had already given copies of the design to GAZ’s Plant No.1. In June 1939, the Council of Soviet People’s Commissars officially gave orders to put the BB-22 into production. The first production aircraft was completed by the end of 1939, and thanks to the political machinations of its designer, made its first flight in February 1940. Production of the aircraft was subsequently delayed. By the end of 1939, of the planned 50, only one was built. Despite these problems, the Soviet Defence Committee issued orders for 580 new aircraft to be built.

 

Work on the Yak-2

Despite the best attempts of Soviet Air Force officials to cancel the BB-22 project, they were hindered by two facts. First was the fact that Stalin personally showed significant interest in its development. Secondly, Yakovlev was appointed as the Deputy People’s Commissar for aircraft production. As a result, the aircraft’s production could not be interrupted. In November 1940, the name of the aircraft was changed to Yak-2, as it was common practice in the Soviet Union to name the aircraft after their designers

By March 1940, after numerous tests and attempts to improve this aircraft, it simply proved to be unusable due to many mechanical flaws. These included the engine overheating, poor flight stability, problems with hydraulics, insufficient quality of bolts that held the wings etc. In total, over 180 faults were reported. The situation was so bad that the Directorate of the Soviet Army Land-based Aviation actually demanded the cancellation of any further work on the Yak-2. On the other side, GAZ No.1 plant officials (who were responsible for the production of this aircraft), along with their test pilots who had flown on this plane, urged its production in order to stay in Yakovlev’s graces. There were plans to produce the first series of 21 aircraft that would be ready by May 1940. After numerous complaints about the Yak-2’s performance, Stalin ordered that the whole situation be investigated. To avoid any kind of guilt, Yakovlev simply blamed the GAZ No.1 production plant for the Yak-2’s poor quality. Ultimately, only 100 Yak-2s would be built and given to the Air Force for operational use.

 

Yak-2 side view. Source: Pinterest

Technical characteristics

The Yak-2 was designed as a twin-engined, mixed-construction low-wing light bomber. The frontal part of the fuselage was made of duralumin. The central part of the fuselage, which was integrated into the wings, was made of wood. The rear part of the fuselage consisted of a welded steel tube frame that was covered with fabric. This rear part could be, if needed (for repairs for example), be separated from the remainder of the aircraft.

The Yak-2 was powered by two Klimov M-103 960 hp liquid cooled engines. The two engines were placed in wing nacelles, on each side of the central fuselage.

op view of the Yak-2. The two engines could be clearly seen. Source: Wiki

The Yak-2 had standard retractable landing gear units, which consisted of two larger frontal wheels and one smaller to the rear. All three retracted to the rear, with the frontal two retracting into the engine nacelles. While, initially, the aircraft had only one large frontal landing wheel on each side, the majority would be built with twin-wheels on each side.

Unusually, the wings were built using only a single large piece. This greatly limited the possibility of transporting this plane by rail. The wings were built using two metal spar structures which were covered with plywood skin. At the rear of the fuselage, the twin-finned tail was positioned.

While it was based on the BB-22, unlike it, the Yak-2 received a modified canopy with both crew members being placed in it. The pilot was placed in front, while the navigator/rear gunner was placed behind him. This arrangement provided easier crew communication.

The Yak-2 had a crew of two, with the pilot placed to the front and the navigator/machine gunner to the rear. Source: Pinterest

The armament of this aircraft consisted of two rear positioned 7.62 mm (0.3 in) machine guns. These were placed in a small cupola that could be raised higher up to provide better covering fire. There was a provision for an internal bombing bay that could hold 400 kg (880 lbs) of bombs. In addition, the aircraft could carry up to 100 kg (210 lbs) bombs in external bomb racks

In combat

Despite its obvious mechanical unreliability, the Yak-2 would be allocated for operational service. The first group of 25 aircraft were initially allocated to the Kharkov Military District. Due to many mechanical problems, they could not be used for flying. Even at this time, there were still attempts to somehow improve the Yak-2’s overall performance, with minimal results. When the aircraft was fully equipped with military equipment, such as radio, weapons, and full fuel load, the flight performance dropped dramatically. For example, the maximum speed was reduced to 399 km/h (247 mph). In addition, the Yak-2 struggled to reach heights of 8,100 m (26,500 ft), which were some 2,800 m (8.800 ft) lower than those reached during prototype testing.

When the war with the Germans broke out, some 75 Yak-2s were allocated to the 136th Bomber Regiment located in Kiev and the 316th Reconnaissance Regiment in the western district. Their use was quite limited, as most were destroyed on the ground by the German Air Force. At least one was shot down by friendly aircraft fighters.

 

The majority of Yak-2s were destroyed on the ground by the German Air bomb raids. Source Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland
Some did survive the initial German Air raids but would be lost in the following weeks. Here, a group of three Yak-2s on their way to bomb German positions can be seen. Source: Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland

Proposed versions

Despite its generally poor performance of the Yak-2, there were some attempts to reuse this aircraft for other purposes. These included the BPB-22 short-range bomber, R-12 reconnaissance, I-29 escort fighter, Yak-2KABB ground attack aircraft, and a trainer version.

The BPB-22

The GAZ. No.81 production plant, on its own initiative, tried to develop a short-range dive bomber based on the BB-22. For this proposal, they equipped one aircraft with the newly developed M-105 engines and added dive brakes. The first flight test made in October 1940 was disappointing and the project was canceled.

R-12 reconnaissance

Based on elements from No-22 and the Yak-2, a reconnaissance aircraft named R-12 was to be developed. This aircraft was to be powered by 960 hp M-103 engines. In the end, nothing came of this project.

Yak-2KABB

This was a ground attack prototype equipped with bombs, two 20 mm (0.78 in) cannons, and two machine guns placed under the fuselage. It also received a new modified cockpit design. The aircraft was tested in a series of evaluation flights and was generally considered to be a good design. The outbreak of the war stopped any further work on this aircraft.

The experimental Yak-2KABB. Source: Y. Gordon, D, Khazanov and S. Komissarov OKB Yakovlev, Midland

I-29

The I-29 was a heavy escort fighter that was to be armed with two 20 mm (0.78 in) cannons. While work on this aircraft continued up to 1942, it would ultimately be canceled.

A trainer version

One Yak-2 was built as a dual-control trainer aircraft. While it was tested in March 1941, nothing came from this project. It is not known if this version ever received any official designation.

Production

Being an unsuccessful design, the actual production run was limited. The Yak-2 was produced by the GAZ No.1 production plant, which built around 25 aircraft. The Moscow Aircraft factory No.81 produced some 75 Yak-2s which were slightly improved in quality but, otherwise, were the same. By the time production ended, only around 100 aircraft were built.

  • No-22/BB-22 Prototype – The first prototype built during the summer of 1939, which served as a base for the Yak-2
  • Yak-2 – Main production version
  • Yak-2KABB – A ground attack prototype
  • BPB-22 – Short-range bomber, one prototype built
  • R-12 – Reconnaissance version proposal
  • I-12 – Escort fighter proposal
  • Trainer Aircraft – One prototype of a dual-control trainer version was built but was not accepted for service

Conclusion

While it managed to achieve extraordinary speed during the prototype phase, in the military role, the Yak-2 proved to be a disappointing design. Once it was fitted with armament and other equipment, its performance dropped dramatically. This, together with other design problems, ultimately led to the cancelation of this project after only 100 built aircraft.

Specifications –  Yak-2 Specifications
Wingspan 45 ft 11 in / 14 m
Length 30 ft 7 in / 14 m
Wing Area 316.4 ft² / 29.4 m²
Engine Two M-103 960 hp engines
Empty Weight 9,390 lb / 4,260 kg
Maximum Takeoff Weight 12,410 lb / 5,630 kg
Fuel Capacity 600 liters
Maximum Speed 310 mph / 500 km/h
Cruising Speed 255 mph / 410 km/h
Range 560 mi / 900 km
Maximum Service Ceiling 28,545 ft / 8,700 m
Crew One pilot and one navigator/gunner
Armament
  • Two 7.92 mm (0.3 in) machine guns
  • 400 to 500 kg (880 to 1100 lbs) bombs

Gallery

Yak-2 (BB-22) – 316th RAP Lt.I.M.Agarkov. South-West Front – July-August 1941
Illustration by Ed Jackson

 

  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata SSSR, Beograd.
  • B. Gunston and Y. Gordon (1977)Yakovlev Aircraft Since 1924, Putnam Aeronautical Books.
  • Y. Gordon, D, Khazanov (1999) Soviet Combat Aircraft, Midland Publishing.
  • Y. Gordon, D, Khazanov, and S. Komissarov (2005) OKB Yakovlev, Midland.

Rockwell B-1A Lancer

USA flag United States of America (1974)
Prototype Supersonic Heavy Bomber – 4 Built

B-1A 74-0159

The B-1A program arose out of a need for a long-range, supersonic, low-flying heavy bomber. The program’s initial development was pushed forward through an ever-shifting geopolitical landscape, as well as opposition and contention among the the top levels of the U.S. government. Even with advanced features such as variable sweep wings, and variable air intake and exhaust capability, it was derided as a ‘dinosaur’ in the age of ICBMs. The opposition and political infighting nearly ended the Lancer, before it was given a miraculous second chance.

History

B-1A 74-158 taxiing on ground. (U.S. Air Force photo)

The origin of the Rockwell B-1 can be traced back to 1961, when the Air Force began to consider alternatives to the North American B-70 Valkyrie, which had just been downgraded from production to test aircraft status. At that time, the long range strategic missile was assumed to be the weapon of the future, with manned long-range bombers being relegated to a secondary role. The B-70 had been designed to fly at extremely high altitudes and at Mach 3 speeds, and increasingly effective Soviet anti aircraft defenses had made such an aircraft rather vulnerable.

Nevertheless, the Air Force commissioned several studies to explore possible roles for manned bombers in future planning. If successful, these would replace the B-52. At this time, the ability to fly through enemy airspace at extremely low altitudes was was thought to be the key for survival in the face of sophisticated air defenses.

The first such study was known as the Subsonic Low Altitude Bomber (SLAB), which was completed in 1961. It envisaged a 500,000 pound fixed-wing aircraft with a total range of 11,000 nautical miles, with 4300 nm of these miles being flown at low altitudes. This was followed soon after by the Extended Range Strike Aircraft (ERSA), which had a weight of 600,000 pounds and featured a variable sweep wing. The ERSA was supposed to be able to carry a payload of 10,000 pounds and achieve a range of 8750 nautical miles, with 2500 of these miles being flown at altitudes as low as 500 feet. In August of 1963, a third study known as Low-Altitude Manned Penetrator(LAMP) was completed. It called for a 20,000 payload and a 6200 nautical mile range, 2000 miles being flown at low altitude. None of these projects ever got beyond the basic concept stage.

In October of 1963, the Air Force looked over these proposals and used the results as the foundation of a new bomber proposal, termed Advanced Manned Precision Strike System (AMPSS). In November of that year, 3 contractors were issued Requests for Proposals for the AMPSS. The companies were Boeing, General Dynamics, and North American. However, Secretary of Defense Robert McNamara kept a tight rein on funds, and expressed doubts about the assumptions behind AMPSS, so the RFPs only involved basic concept studies and did not focus on a specific aircraft. In addition, the contractors all agreed that some of the suggested USAF requirements either did not make much sense or else were prohibitively costly.

In mid-1964, the USAF had revised its requirements and retitled the project as Advanced Manned Strategic Aircraft (AMSA). The AMSA still envisaged an aircraft with the takeoff and low-altitude performance characteristics of the AMPSS, but in addition asked for a high-altitude supersonic performance capability. The projected gross weight for the aircraft was 375,000 pounds, and the range was to be 6300 nautical miles, 2000 of which would be flown at low altitude.

Secretary McNamara was never very excited about the AMSA, since he thought that strategic missiles could do a better job of “assured destruction” than manned bombers, and thought that the cost of the AMSA would probably be excessive. Nevertheless, there was a potential gain in avionics and propulsion technology that could be achieved if the project were to proceed, and McNamara released a small amount of funding for preliminary AMSA studies. The airframe for the AMSA would be worked on by Boeing, General Dynamics, and North American, whereas Curtiss-Wright, General Electric, and Pratt & Whitney would work on the engines. Both IBM and Hughes aircraft looked at potential avionics systems. These contractors issued their reports in late 1964. General Electric and Pratt & Whitney were given a contract to produce two demonstrator engines, but no airframe and avionics contracts were issued at that time.

74-0160 on display at Edwards AFB in 1980. (U.S. Air Force photo)

A bit of confusion entered the picture when the Defense Department selected the FB-111A as the replacement for the B-52C, B-52F, and B-58. The Air Force had not requested a bomber version of the controversial F-111, and was not all that enthusiastic about the choice. Nevertheless, a low-cost interim bomber did have some attractive features, and the Air Force went along with the choice of the FB-111A provided it did not interfere with AMSA development.

By 1968, an advanced development contract was issued to IBM and the Autonetics Division of North American Rockwell. On September 22, 1967, North American Aviation had merged with Rockwell Standard Corporation to create North American Rockwell. Earlier in that year, the Joint Chiefs of Staff had recommended the immediate development of the AMSA, but Secretary McNamara was still opposed, preferring instead to upgrade the existing FB-111 and B-52 fleet. McNamara vetoed the proposal.

When Richard Nixon became President in January of 1969, his Secretary of Defense Melvin Laird reviewed Defense Department needs and announced in March of 1969 that the planned acquisition of 253 FB-111s would be reduced to only 76, since the FB-111 lacked the range and payload required for strategic operations, and recommended that the AMSA design studies be accelerated.

The AMSA was officially assigned the designation B-1A in April of 1969. This was the first entry in the new bomber designation series, first created in 1962.

New Requests For Proposals were issued in November of 1969. IBM and Autonetics were selected for the avionics work on December 19. The selection of airframe and engine contractors was delayed by budget cuts in FY 1970 and 1971. On December 8, 1969 North American Rockwell and General Electric were announced as the winners of the respective airframe and engine contracts for the B-1A.

The original program called for 2 test airframes, 5 flyable aircraft, and 40 engines. This was cut in 1971 to one ground test aircraft and 3 flight test articles (74-0158/0160). First flight was set for April of 1974. A fourth prototype (76-1074) was ordered in the FY 1976 budget. This fourth plane was to be built to production standards. At one time, some 240 B-1As were to be built, with initial operational capability set for 1979.

Design

B-1A Orthogonal Projection. Note the difference between the wings at maximum and minimum sweep. (U.S. Air Force photo)

The fuselage of the B-1A was fairly slim, and seated a crew of four in the nose. There was a large swept vertical tail, with a set of all-flying slab tailplanes mounted fairly high on the vertical tail. The aircraft’s fuselage blended smoothly into the wing to enhance lift and reduce drag. In addition, the fuselage was designed to reduce the aircraft’s radar cross section in order to minimize the probability of detection by enemy defenses.

In order to achieve the required high-speed performance and still be able to have a good low-speed takeoff and landing capability, a variable-sweep wing was used. This made it possible for the aircraft to use short runways that would be inaccessible to the B-52. The outer wing panels were attached to a wing carry-through attachment box which faired smoothly into a slim, narrow fuselage. Each outer wing had full-span slats and slotted flaps, but used no ailerons. Lateral control was provided by a set of spoilers on the wing upper surface, acting in conjunction with differential operation of the slab tailplanes.

The engines were four afterburning General Electric F101-100 turbofans. The engines were installed in pairs inside large nacelles underneath the wing roots,, and close to the aircraft’s center of gravity to improve stability while flying at high speed through highly-turbulent low-altitude air. The nacelles were far enough apart so that the main landing gear members could be installed in the wing roots between them with enough clearance to retract inwards. In order to achieve the required Mach 2 performance at high altitudes, the air intake inlets were variable. In addition, the exhaust nozzles were fully variable.

Initially, it had been expected that a Mach 1.2 performance could be achieved at low altitude, which required that titanium rather than aluminum be used in critical areas in the fuselage and wing structure. However, this low altitude performance requirement was lowered to only Mach 0.85, enabling a greater percentage of aluminum to be used, lowering the overall cost. Titanium was used primarily for the wing carry-through box, the inner ends of the outer wings incorporating the pivots, and for some areas around the engines and rear fuselage.

Eight integral fuel tanks were planned, one in each outer wing panel, and the rest in the fuselage. About 150,000 pounds of fuel could be carried. There were three 15-foot weapons bays in the lower fuselage, two ahead and one behind the wing carry-through box. Each bay could carry up to 25,000 pounds of conventional or nuclear weapons. The total weapons load was almost twice what a B-52 could carry. All of the offensive weapons were to be carried internally, with no provision for externally-mounted pylons. A key weapon was to be the AGM-69A SRAM (Short-Range Attack Missile), 8 of which could be carried on a rotary launcher in each of the weapons bays.

No defensive armament was planned, the B-1A relying on its low-altitude performance and its suite of electronic countermeasures gear to avoid interception.

An extensive suite of electronics was planned, including a Litton LN-15 inertial navigation system, a Doppler radar altimeter, a Hughes forward-looking infrared, and a General Electric APQ-114 forward-looking radar and a Texas Instruments APQ-146 terrain-following radar.

The B-1A carried a crew of four–a pilot, copilot, offensive systems officer, and defensive systems officer. The crew escape system resembled that of the F-111 crew escape module. In an emergency, a capsule containing all four crewmembers would separate from the aircraft and be steered and stabilized by various fins and spoilers. A rocket motor would fire and lift the capsule up and away from the aircraft. Three parachutes would then open and would lower the capsule along with the crew safely to the surface. Once down, the capsule would serve as a survival shelter for the crew members.

Development

The B-1A mockup review occurred in late October of 1971. There were 297 requests for alterations.

The first B-1 flight aircraft (74-0158) rolled out from USAF Plant 42 at Palmdale, CA on October 26, 1974. It made its first flight on December 23, 1974, a short hop to Edwards AFB where the flight testing was to be carried out. The crew was Rockwell test pilot Charlie C. Bock,; Jr, Col. Emil Sturmthal, and Richard Abrams. The third aircraft (74-0160) was to be the avionics testbed and flew for the first time on March 26, 1976. The second aircraft (74-0159) was initially used for some static ground testing and did not make its first flight until June 14, 1976.

The B-1A test program went fairly smoothly. However, there were numerous modifications introduced throughout the program and some items of additional equipment were added. The avionics suite of the B-1A was perhaps the most complex yet used on an aircraft. The Initial Operational Test and Evaluation tests were successfully passed in September of 1976. The Phase 1 flight test program was completed on September 30, 1976. In December of 1976, the Air Force concluded that the B-1A was to go into production, with contracts placed for the first three aircraft and plans were made for an initial Block 2 production batch of 8 aircraft.

It seemed that the B-1A was well on its way to a full production run of 240 aircraft. However, the cost of the B-1A program began to escalate, and there were still some unresolved issues concerning the avionics suite. In 1970, the estimated per-unit price was $40 million, and by 1972, the cost had risen to $45.6 million. Although this sounds like small-change by today’s standards, this was considerably greater than the figure for any previous production aircraft. Moreover, by 1975, this number had climbed to $70 million.

Alarmed at these rising costs, the new presidential administration of Jimmy Carter (which had taken office on January 20, 1977) began to take a second look at the whole B-1A program. On June 30, 1977, President Carter announced that plans to produce the B-1A would be cancelled, and that the defense needs of the USA would be met by ICBMs, SLBMs, and a fleet of modernized B-52s armed with ALCMs. President Carter genuinely wanted to reduce the arms race, but he was unaware at the time of the secret projects that would ultimately lead to the F-117A stealth attack aircraft and the B-2 Spirit stealth bomber.

B-1A during the B-1B flight test program. (U.S. Air Force photo)

Despite the cancellation of the production program, the Carter administration allowed the flight testing of the B-1A to continue. Most of the effort involved the avionics, in particular the defensive systems. In addition, General Electric continued to work on improvements for the F101 engine, and most of the contractors kept their engineering teams intact. Perhaps most important, work continued in reducing the radar cross section of the aircraft. Less than a month after the cancellation, 74-0160 launched a SRAM on July 28, 1977 at an altitude of 6,000 feet over the White Sands missile range. This aircraft was later modified with an advanced electronic countermeasures system mounted in a dorsal spine, and Doppler beam sharpening was added to the forward-looking radar. 74-0158 had achieved Mach 2.0 in April of 1976, and after completing its stability and control tests was placed in storage in 1978. On October 5, 1978, 74-0159 achieved a speed of Mach 2.22, the highest speed achieved during the B-1A program.

74-0158 was retired from flying in April of 1981 after having flown 138 sorties, the largest number of flights of any of the prototypes. By this time, it had acquired a three-tone desert camouflage scheme. It was eventually dismantled and used as a weapons trainer at Lowry AFB.

74-0159 was later used as a flight test article in the B-1B program. It was modified by having B-1B flight control system features installed. It began flying on March 23, 1983. Unfortunately, it crashed on August 29, 1984 when the aircraft’s center of gravity got unbalanced during fuel transfer management procedures, causing it to lose control. The escape capsule deployed successfully, but the parachute risers did not deploy properly. The capsule hit the ground at a steep angle, so steep that the inflatable cushions could not shield the impact. Chief test pilot Doug Benefield was killed, and two other crew members were seriously injured.

74-0160 was later converted to a ground trainer under the designation GB-1A and is now on display at the Wings Over The Rockies Air and Space Museum (formerly Lowry AFB), near Denver, Colorado.

76-0174 had been ordered to serve as a pre-production B-1A aircraft and was configured with full avionics systems. When the B-1A program was cancelled, work on this aircraft was well under way. Unlike the first three B-1s, 76-0174 was equipped with four conventional ejector seats in place of the escape capsule. This change was made after tests had determined that the crew escape module was unstable if ejected at speeds above 347 knots. It flew on February 14, 1979 and carried out 70 sorties. This plane was later used as a test article in support of the B-1B program. It resumed flying on July 30, 1984. Externally, the main change was the removal of the long dorsal spine but many of the B-1B avionics systems were installed internally. It is now on display at the USAF Museum at Wright Patterson AFB in Ohio.

Variants

  • B-1A – The initial prototype run of four aircraft

Operators

  • U.S. Air Force – The sole operator of the B-1A was the USAF

 

B-1A Lancer

Wingspan
(at max sweep)
78 ft 2.5 in / 23.84 m
Wingspan
(at min sweep)
136 ft 8.5 in / 41.67 m
Length 143 ft 3.5 in / 43.8 m
Height 34 ft 0 in / 10.36 m
Wing Area 1,950 ft² / 181.2 m²
Engine 4x General Electric F101-GE-100 turbofans, 17,390 lbf dry, 30,000 lbf with afterburner
Fuel Capacity 29,755 US Gal / 11,2634 L
Loaded Weight 389,000 lb / 176,450 kg
Maximum Take Off Weight 395,000 lb / 179,170 kg
Maximum Speed Mach 2.2 / 1,688 mph / 2716.5 kmh at 50,000 ft / 15,240 m
Maximum Service Ceiling 62,000 ft / 18,900 m
Crew 1 pilot, 1 copilot, 1 offensive systems officer, 1 defensive systems officer

Gallery

Illustrations by Basilisk https://basilisk2.deviantart.com

B-1A 74-0158 seen in Anti-Flash White
B-1A 74-0160 seen in a SAC Low Level Livery
B-1A 76-0174 seen in camouflage paint scheme
B-1A 76-174 seen in camouflage during testing. (U.S. Air Force photo)
A right side ground view of a B-1A aircraft wearing dark green camo. (U.S. Air Force Photo)
B-1A 76-174 in flight with wings extended in the 25-degree sweep position. (U.S. Air Force photo)

Sources

Saab 18

sweden flag Sweden (1944)
Bomber – 245 Built

The Saab 18 is another example of Sweden’s efforts to produce an aircraft to safeguard its neutrality, considering that the same War and international political context prompted the Scandinavian nation to do so. Only that this plane was not devised to keep the skies of Sweden, but rather to protect the national territory from the air. Curiously, when WWII started, the Saab B 17 was given priority at the earlier stages of the war, as a dive bomber was considered more necessary than a light/medium bomber. This plane gave also important contributions to the development of the Swedish aeronautic and military industry, contributing in the development of ejection seats and of air-to-surface (or AGM) missiles; more specifically, anti-ship missiles. Despite being required to maintain Sweden’s neutrality and protect its territory, it entered in service in 1944, quite late to address the threat from Germany but ready to address the threat from the East and to serve at the early days of the Cold War, with distinction. It became also the standard bomber of the Flygvapnet.

The Saab B 18 is a light bomber and reconnaissance plane with three seats, two engines and a double tail, with a design similar to that of the Junkers Ju 86 and the Dornier Do 17 with the rounded shape of the vertical stabilizers. Or simply the very characteristic shape of double tail and double engine bombers of the era: this is, the cockpit placed at the frontal section of the plane and with the bow being made entirely of glass (normally the place of the bomber), and the cockpit being of a glazed offset type with the pilot and navigator. The wing has a trapezoid shape, being a straight leading edge type with the rear part being instead angled.

The Saab B 18 was initially intended to be powered by British-made Bristol Taurus engines. But it received in the end two types of engines during its career as the Taurus engines weren’t available, powered instead with two Pratt & Whitney R-1830 Twin Wasp radial engines of 1065 hp (the Saab J 21 had priority in receiving the Daimler Benz engines). Posterior versions received new powerplants as the Pratt & Whitney were deemed insufficient, hence receiving 2 Daimler Benz DB 605 of 1475 hp, enabling the plane to reach speeds of up to 570 km/h (357 mph), and making of the B 18 one of the fastest light bombers producing during the war. The powerplant was not the only modification the B 18 suffered during its service with the Flygvapnet, as the initial configuration of armament of 3 x 13,2 mm machine guns was changed to a set of one 7,92mm gun and 2 X 13,2mm machine guns (B 18B). Another re-configuration was the instalment of 2 X 20mm cannons and a 57mm gun (T 18B), along with rockets instead of bombs. Noteworthy to point out that the B 18 could carry up to 1,000 kg of bombs in the compartment and 8 x 50 kg bombs at the wings. As reconnaissance and torpedo-bomber variants were developed (though the last one was never put into service), the versatility and adaptability of the B 18 was made evident, at the point of being the platform for testing the Rb 302 anti-ship missiles. The crew was also modified, as following versions needed only two crewmen as rockets were introduced, suppressing the bomber.

Both versions (B 18B and T 18B) received another modification of armament in the 50’s, as they were fitted with rocket launchers allowing a maximum of 4 rockets on each wing, and even another rocket launcher allowing 2 or 4 rockets under the nose. The bomb sight was also equipped with an automatic reflex sight for rocket firing. This conversion meant that the B18B and the T18B would have increased – and more specialized – attack roles. Also, both the B 18B and the T 18B received ejection seats, maximizing the safety of the crew operating with these air assets. In addition, some B18 B units were fitted with two radars (a radar altimeter PH-10 and a search radar PS-18/A, which was a US Navy AN/APS-4 naval radar) for target designation and identification.

This airplane was purposed at replacing the Junkers Ju 86 in service with the Swedish Air Force back then, basing the requirement for a fast bomber with a crew of three. This was later on changed to a bomber having a crew of 3, a bomb payload of up to 750 kg (1653,46 lb), capable of reaching speeds of 500 km/h (310,68 mph) and to be used as a long-range reconnaissance, torpedo-bomber and heavy fighter. The fact that the B 18 ended in serving with the Flygvapnet was a sheer product of luck, as the competition’s design (the GV8 proposed by the competing AB Götaverken) was capable of meeting the requirements. Yet its costs and the departure of Götaverken’s chief designer resulted in Saab awarding the contract in 1938. As development began, many Americans reportedly took part in the design and development process, resulting in the B 18 having some “American traits” in the design. As a result, the B 18 development had a Swedish and an American chief designer: Frid Wänström and Carl Haddon, respectively.

The development process was delayed by two factors explaining the reasons of the Saab B 18 entering in service relatively late: first, the abovementioned shifting in priorities once the war started, with the Saab B 17 dive bomber receiving priority over the Saab B 18. And second, a change in requirements from a light bomber to a medium bomber, which ended in increasing the development time. The first flight took place in 1942, entering in service in 1944 with two initial versions: the B 18A bomber and the S 18A reconnaissance versions. A torpedo-bomber and later attack plane (T 18B), and a dive bomber (B 18B) were developed, receiving ejection seats.

After WWII and in the wake of the Cold War, the B 18B had a very interesting career, as the increase of the Soviet threat asked for reconnaissance missions; in 1945 and 1946 the B18 B was used to reach the Baltic coast and take pictures of every Soviet vessel, meeting Soviet fighters almost every time.

244 units were produced with the Flygvapnet being the sole operator until 1959, year in which the Saab 32 Lansen replaced the B 18: 62 units of the B 18A, 120 units of the B 18B, and 62 units off the T 18B were built. A single surviving airframe is displayed at the Flygvapenmuseum.

Design

The design of the B 18 is very typical of the pre-WWII double-tail light or medium bombers, having some interesting features despite its conventional sight at first glance. The B 18 is a straight leading edge wing airplane, with the engines placed at the first half of the wings. The fuselage was entirely made of metal, with fabric covering the control surfaces, and having the armor being integrally part of the structure.

The most remarkable areas are the canopy, the bow section, and the rear horizontal stabilizers, connecting the two vertical stabilizers with the main airframe. Regarding the canopy and bow section, the canopy is not placed at the longitudinal middle of the plane as it is normally placed, being instead an offset type at the left side. There, the pilot and the navigator were stationed, with the navigator seat being placed backwards. In addition, the bow section had a glazed tip where the bomber was stationed. Reportedly, such scheme improved the visibility for the pilot. The nose of the T 18B version was slightly modified. And the bow inferior section is not entirely straight, having instead an undernose gondola right before the wing-roots. The landing gear was of classic configuration, with the frontal landing gears retracting into the engine gondolas, while the small rear landing gear was placed at the stern of the bomber, right before the horizontal and vertical stabilizers area. In turn, the horizontal stabilizers are of a ‘butterfly shape’, having at the tips the two horizontal stabilizers; the rudders occupied the whole posterior area of the tails. The shape of the vertical stabilizers is of an isosceles trapezoid.

The wing is a mid-wing (cantilever) leading edge wing, with a shape of a right trapezoid and where the two engines are installed, along with the main fuel tanks. In some versions, there was a gun or a cannon installed at one of the wing-roots. The engines, depending of the version, were either a couple of Pratt & Whitney R-1830 Twin Wasp radial engines or a couple of licensed-built Daimler Benz DB 605 liquid cooled inline V-inverted engines. Depending of the installed engines, the air intake might be located below the engine gondola or above the engine gondola. Normally the earlier versions of the B 18 can be identifying by the intakes placed above the engine gondola. The Daimler Benz engine gave the B 18 a quite remarkable speed for a plane of its type back then, being among the fast ones with speeds of 575 km/h (357 mph). Such speed would provide an advantage for attack and reconnaissance missions. Reportedly, the T 18B version could reach speeds of up to 600 km/h (372,82 mph). The propellers of the B 18 where a three-bladed type.

The armament configuration also varied from version to version. The initial configuration was of 3 x 13,2mm machine guns, one firing forwards at the wing root, another firing also forwards at the nose, and another at the rear. This set was then changed for a set of one wing root 7,62mm machine gun and two 13,2mm guns, and then it was changed for a set of a front-firing 57mm Bofors gun at the undernose gondola and 2 x 20mm guns. The B 18 could carry up to 1,000 kg (2,200 lb) bomb and the bombs compartment and up to 8 x 50 kg (110 lb) bombs at the wings. This type of offensive armament was also changed, as it was first modified to carry a torpedo, which never came to be operational, and then it carried up to eight air-to-surface rockets. The B 18 was also used to test the Rb 302 anti-ship missile. The reconnaissance version was fitted with various cameras to perform its mission, along with a radar.

The B 18 was among the first planes in receiving ejection seats, as its high attrition rate made the Flygvapnet to implement such measure for the sake of the crew’s safety. The fact that it had ejection seats and capacity to carry missiles, along with its speed and un-conventional design, makes the B 18 a very interesting design made by a neutral nation during WWII and the early Cold War.

A Versatile Guardian of the Swedish Land

The B 18, although entering quite late to have a remarkable role in defending Sweden’s neutrality as WWII unfolded, it became a very valuable asset for the Nordic nation at the last stage of the war, when the Soviet Union became stronger and advanced towards the West, with the Cold War highlighting the threat it posed to Sweden. Not only its speed and considerable armament made the B 18 an air asset to be reckoned with, but also its versatility and adaptability, let alone its flexibility. The design allowed the installation of new engines that increased the speed of the B 18, as well as a change of armament while in service, at the point of serving as a test bed for one of the earlier anti-ship missiles, the Rb 302. These modifications allowed the B 18 to become very effective bomber and ground-attack planes, and even to serve as a reconnaissance plane capable of approaching or even penetrating Soviet airspace for its missions, facing quite often the Soviet fighters.

Striking at Speed

One of the characteristics that made the B 18 an airplane to be reckoned with was beyond any doubt its speed, especially after the Daimler Benz 305. The B 18B could reach speed of 570 km/h (357 mph), and the T 18B, the most powerful version in terms of firepower, could reach speeds of up to 600 km/h (372,82 mph). This was an advantage when it came to perform bombing or strike attacks with rockets, as the B 18 could have hit any advancing enemy ground forces formation with hit-and-run tactics or simply by direct strikes with devastating effects. Curiously, the S 18A was the slowest version, with speeds of up to 465 km/h being the maximum speed; this can be explained by the fact it was powered by the previous Pratt & Whitney engines, as the S 18A was a direct modification from the B 18A, which was (under)powered by such engines. Nevertheless, as the powerplants were enhanced, the B 18 became a very fast medium bomber. And it could have posed a serious threat to naval surface units approaching the Swedish coast.

Variants of the Saab B 18

  • 18A – Two prototypes powered by Pratt & Whitney R-1830 Twin Wasp engines of 1065 hp.
  • B 18A – This version became the first series version of the B 18, powered with the abovementioned Pratt & Whitney engines. Armed with 3 x 13,2 mm machine guns and up to 1400 kg (3086.47 lbs). 55 units were reportedly converted into the S 18A reconnaissance version in 146-47. 62 units delivered.
  • S 18A – A modified version of the B 18A for reconnaissance purposes, replacing the Caproni Ca 313 (S16) reconnaissance plane in service back then. It was fitted with a varied array of cameras: 3 high-altitude 10/92 and 5/25 cm cameras, 1 panoramic 10/105 cm camera and a 13/30 cm night camera. This version was also fitted with a PS-18A (An American-made AN/APS-4) maritime surveillance radar, with 36 units having this radar installed in pods under the nose, and serving as maritime reconnaissance airplanes.
  • Saab 18B – A single prototype powered with the Daimler Benz DB 605B.
  • B 18B – A dive bomber version powered by the new Daimler Benz DB 605B of 1475 hp engines. It was later on modified to carry up to 8 air-to-surface rockets, becoming an attack plane. Armed with a 13 mm machine gun and a 20 mm gun plus the 1400 kg (3086.47 lbs) payload of bombs, and later on the 8 air-to-surface rockets. A dive bomb sight m/42 developed by Saab engineer Erik Wilkenson maximized its attack capabilities. Reportedly, some B 18B received a PS-18A radar. This version received ejection seats, and had the crew modified, reducing it to two (pilot and navigator/radio operator). 120 units delivered.
  • T 18B – A projected torpedo-bomber to serve as an anti-ship asset, it ended in being a ground-attack plane thus receiving an armament of a 13mm machine gun, 2 x 20mm guns and a 57mm Bofors cannon at the undernose gondola, receiving later on air-to-surface rockets. This version also received ejection seats. 62 units delivered.

Operators

  • Sweden
    The Flygvapnet was the sole operator of the B 18, which entered in service in 1944 with 62 units of the B 18A model, followed shortly by 120 units of the B 18B that were initially purposed as dive bombers, developed later on into the T 18B with 62 units, which served as a ground-attack plane. The T 18B, in turn, was initially purposed to be a torpedo-bomber, but given problems with the new payload, received instead rockets hence serving as attacker. Some airframes were modified to be the S 18A reconnaissance plane, performing reconnaissance missions off the Soviet Baltic coast in the aftermath of WWII. It remained in service until 1958, year in which the Saab 32 Lansen replaced the B 18. It was used for testing the Rb 302 anti-ship missiles. The B 18B operated in 4 squadrons from 1944 to 1958: F1 Västerås, F7 Såtenäs, F14 Halmstad, and F17 Kallinge. The T 18B torpedo-bomber/attack aircraft operated also in the F17 Kallinge from 1948 to 1958. The S 18A operated in three squadrons in the same perios of time: F3 Malmen, F11 Nyköping and F 21 Luleå. A single B 18B recovered from a lake remains as a museum exhibition.

Specifications (B-18B)

Length 13.23m / 43ft 5in
Wingspan 17m / 56ft 9in
Height 4.35m / 14ft / 3in
Wing Area 43.75m2 / 470.92 ft2
Engine 2 X Daimler Benz DB 605 of 1475hp (some were licensed-built versions made by Svenska flygmotor AB).
Maximum Take-Off Weight 8800kg / 19,401 lb
Empty Weight 6100 kg (13,448 lb)
Loaded Weight 8140 kg (17,948 lb) (B 18A)
Maximum Speed 570Km/h / 357 mph
Range 2600 km /1,616 miles
Maximum Service Ceiling 9800m / 32,150ft
Crew 3 (2 in the T-18B)
Armament
  • A 13mm machine gun; 20mm cannon
  • A 13mm machine gun; 2x 20mm cannon; a 57mm gun (T 18B)
  • Up to 1400kg of bombs and rockets (the T18 B was intended to carry a torpedo or a mine, but it ended in having a payload of rockets)

Gallery

SAAB B18B

Sources

Arboga Robotmuseum. (2017). Rb 302. Arboga Robotmuseum.Aviastar.org (n.d.). Saab 18. 1942. Aviastar.org.Hertze, S. (2017). B18, B18A, B18B, T18B, S18A, Saab 18. Arboga Elektronikhistorika Förening AEF.Frederiksson, U. (2005). Saab B 18, the Swedish Air Force’s last propeller combat aircraft. X-plane.org.Henriksson, L. (2010). B18–Saab 18 (1944-1959). Avrosys.nu.Pilotfriend. (n.d.). Saab 18.The Spyflight Website. (2003). Swedish Cold War Reconnaissance.wwiivehicles.com. (2017). Sweden’s Saab B18, Saab 18 bomber. wwiivehicles.com.Saab 18. (2017, May 17). In Wikipedia, The Free Encyclopedia., Images: Saab 18 Forward View by Johnny Comstedt / CC BY-NC-ND 2.0Side Profile Views by Ed Jackson – Artbyedo.com