Category Archives: UK

Boulton-Paul P.105 & P.107

UK Union Jack United Kingdom (1944)
Strike Fighter – None Built

Static model of the standard P.105. [British Secret Projects]
The Boulton-Paul P.105 is a little known single-engine aircraft meant to fill a variety of carrier-based roles. To do so, the P.105 would utilize a unique and innovative design that involved having interchangeable fuselage and cockpit modules that would pertain to a certain mission, and could be changed quickly to fill a needed role aboard carriers or other airbases. The design was not picked up for unknown reasons but its story doesn’t end there. The design would develop further into the P.107, a land-based escort version of the P.105. The P.107 would have a rear-facing turret and a twin boom tail design to allow greater traverse of the gun. This design wouldn’t be adopted either and the program would conclude before the war’s end.

History

Late in the Second World War, the Royal Naval Air Arm began seeking out an aircraft design that would be able to fill both the fighter and bomber roles. Having one aircraft perform multiple roles would eliminate the specialization of carrier-borne aircraft needed to fill the fighter, dive bomber, and torpedo bomber roles. No official requirement was ever put out to build such an aircraft, but several companies had begun developing aircraft that would fit this role, which had become known as the “Strike Fighter”. Westland, Blackburn, Fairey and Boulton-Paul would all develop designs that correspond to the strike fighter role. Boulton-Paul’s aircraft design would be known as the P.105.

Boulton-Paul is a lesser-known aircraft company which only had a single major type of aircraft enter mass production during the Second World War: the Defiant. The Defiant reflected a lot of their aircraft designs, which were all somewhat unorthodox. . In the Defiant’s case, it was a fighter with a rear turret. Boulton-Paul were much more successful in developing turrets for use on other aircraft, such as the Handley-Page Halifax, Blackburn Roc (which they co-developed alongside Blackburn), Lockheed Hudson and the late war Avro Lincoln. Despite having only one combat aircraft enter production, Boulton-Paul had a very active development section, although most of their designs would stay on the drawing board, with a few being lucky enough to receive prototypes. The designs came from an engineer named J. D. North, who was the main aircraft designer for Boulton-Paul. Before work started on their Strike Fighter design, North had been working on their P.103 and P.104 designs for the Naval Air Arm. The P.103 was an ultra-fast fighter design that utilized a contra-rotating propeller and a Griffon 61 or Centaurus engine. The P.103 wasn’t picked up for production, but North would use many aspects of the P.103 in the P.105. The contra-rotating propeller would once again be used, while the engine would start as a Griffon 61 but shift over to a Centaurus engine later.

3 way drawing of the P.105. Note the spotter’s lower window. [British Secret Projects]
The P.105 was meant to be a small, high-performing aircraft that could easily be converted to fill other roles, even carrier duties. To do so, it would use a unique idea. To fill the variety of carrier-borne roles, the P.105 would have modular cockpit and bomb bay sections. The interchangable modules included a torpedo-bomber (P.105A), reconnaissance aircraft (P.105B), fighter (P.105C) and dive-bomber (No designation given). Each section would have minor differences between them that fit their respective roles. With this system, more P.105 airframes could be stored in hangars and carriers, while the additional modules would take up less space than other aircraft specified for specific roles, thus increasing the combat capacity of the carrier the P.105 would be stationed on. Boulton Paul expected the aircraft to be very high performance and the P.105C version would be an excellent penetration fighter. Before any specifications were estimated, it was decided to switch from a Griffon 61 engine to the Centaurus inline engine. The brochure on the details of the aircraft was submitted to the RNAA, but no order for production came about. Exactly why it wasn’t adopted is unknown. The reasoning may come from the module system, as it could have been novel in concept, but complex in reality. Another reason could be that current aircraft at the time were deemed to have been performing adequately and didn’t need such a replacement.

3 way drawing of the P.107. Note the sliding aft canopy and smaller profile of the twin tail rudders. [British Secret Projects]
Although the P.105 wasn’t granted production, its story continues in the Boulton-Paul P.107. The P.107 is an intriguing design since very little information pertaining to its development history is available, but its design and specifications has been found. It can be assumed the P.107 began development during or shortly after the P.105 had been created. The P.107 wouldn’t be operated by the RNAA, but instead by the Royal Air Force as a long-range escort fighter. Major differences between the P.107 and P.105 include the lack of folding wings, the removal of the torpedo blister, the addition of a turret and the switch from a single rudder to a twin tail design to improve the firing angle of the turret. The P.107 could also be configured for different roles, but it is unknown if it used the same module system the P.105 used. The P.107 wasn’t selected for production either.

Design

The Boulton-Paul P.105 had a conventional fighter layout. In the front, it would utilize a contra-rotating propeller that had reversible pitch. Originally, the design would have mounted a Griffon 61 engine but was changed in favor of the Centaurus engine instead. The wings on the P.105 were inverted gull wings, much like those on the Vought F4U Corsair or Junkers Ju 87 Stuka. To conserve space in carriers, the wings would be able to fold. The fuselage had the most interesting aspect of the P.105 overall and that was its interchangeable cockpit and lower fuselage modules. Each variant of the P.105 would use different modules that would pertain to the intended role it served. The P.105A was a torpedo bomber and would use the torpedo blister present under the tail. The P.105B was a reconnaissance aircraft, and its cockpit would sit a pilot and observer. It would use a glass hull beneath the observer to assist in spotting. The P.105C was an escort fighter and would be a one-man aircraft. The last was a dive-bomber version, which only has very sparse details available. The dive bomber would carry two 1,000 lb (450 kg) bombs, most likely in an internal bomb bay module. The tail of the aircraft would be a conventional rudder and tailplane arrangement. The armament of the P.105 was a standard two to four 12.7mm machine-guns in the wings of the aircraft, with the only deviation being the P.105C, which would use four 20mm cannons instead.

Papercraft model of the P.107 [Kartonbau.de]
The P.107 borrowed many aspects of the P.105 design, but changed some details to better fit its role. The engine and frontal section would stay the same, keeping the contra-rotating propellers and Centaurus engine. Reference materials refer to the aircraft as being able to convert from an escort fighter to either a fighter-bomber or photo reconnaissance aircraft. However, whether it was conventional conversion or via the module system the P.105 used is unknown, the latter being most likely. The wing design would stay the same, with the inverted gull wing style. Given its land-based nature, the wings no longer folded to conserve space and the torpedo blister under the tail was removed. Behind the pilot, a gunner would sit and remotely control two 12.7mm machine guns. The machine-guns would be housed within the aircraft, with only the ends of the barrel protruding out. To give the gunner a better firing arc, the single tailfin was switched to a double tailfin. The turret and twin tail design are the most obvious differences between the P.107 and P.105. The aircraft’s fuel would be stored in a main tank and two smaller drop tanks. Fuel amount was expected to give the aircraft a 3,000 mi (4,827 km) range, with up to 30 minutes of combat. The drop tanks could be switched for 2,000 Ib (900 Kg) of bombs. For offensive armament, the P.107 would use four 20m cannons mounted in the wings.

Papercraft model of the P.107 [Kartonbau.de]

Variants

 

  • Boulton Paul P.105A– Torpedo bomber version of the P.105.
  • Boulton Paul P.105B– Reconnaissance version of the P.105. This version would have a glazed hull for the observer.
  • Boulton Paul P.105C– Fighter version of the P.105.
  • Boulton Paul P.105 Dive bomber– Dive bomber version of the P.105. No designation was given to this design.
  • Boulton Paul P.107– Land-based escort fighter derived from the P.105. The P.107 was near identical to the P.105 but had a twin boom tail to allow better vision and turn radius for a rear mounted turret. Photo reconnaissance and fighter bomber versions of the P.107 are also mentioned.

Operators

 

  • Great Britain – Had it been built, the P.105 would have been used by the Royal Fleet Air Arm. The P.107 would have been used by the RAF for escort duty had it been built.

Boulton-Paul P.105 Specifications

Wingspan 38 ft / 11.6 m
Length 34 ft 5 in / 10.5 m
Folded Width 15 ft 4 in / 4.67 m
Wing Area 250 ft² / 23.3 m²
Engine 3,000 hp ( 2,200 kW ) Centaurus CE.12.SM engine
Fuel Capacity 260 gal (1,180 lit)
Weights 12,285 Ib / 5,572 kg with torpedo

12,509 Ib / 5,674 kg with bombs

Climb Rate 3,660 ft/min / 1,110 m/min
Maximum Speed 469 mph / 755 km/h at 20,000 ft / 6,000 m
Cruising Speed 407 mph / 655 km/h
Range 1,300 mi / 2100 km – 3,320 mi / 5340 km
Crew Pilot

Other crew member (Depending on the variant)

Armament
  • 2-4 12.7mm machine guns (All versions)
  • 1x Torpedo (P.105A)
  • 2x 1,000 Ib (454 kg) bombs (Dive Bomber)
  • 4x 20mm cannons (P.105C)

Boulton-Paul P.107 Specifications

Wingspan 38 ft / 11.6 m
Length 34 ft 8 in / 10.6 m
Wing Area 250 ft² / 23.3 m²
Engine 3,000 hp ( 2,200 kW ) Centaurus CE.12.SM engine
Fuel Capacity Main: 495 gal (2,250 lit)

Drop Tanks: 140 gal (640 lit)

Weight 15,900 Ib / 7,200 kg
Max Speed 470 mph / 755 km/h at 22,000 ft / 6,700 m
Range With Drop Tanks: 3,000 mi / 4,800 km

Without: 2,200 mi / 3,540 km

Fighter-Bomber: 700 mi / 1,120 km

Crew 1 Pilot

1 Gunner

Armament
  • 4x 20 mm guns + 2x 12.7mm machine guns
  • 2,000 Ib (907 kg) of bombs

Gallery

Illustrations by Haryo Panji

Boulton-Paul P.107 Illustration by Haryo Panji
Boulton-Paul P.105 Reconnaissance Illustration by Haryo Panji

Credits

Martin-Baker Tankbuster

UK Union Jack United Kingdom (1942)
Anti-Tank Aircraft Design – None Built

3D artist impression of the Tankbuster in flight [candymountain.jp]
The Martin-Baker Tankbuster was a concept British anti-tank aircraft that was designed according to an order in 1942 for a specialized ground attacker. The aircraft had a twin-boom, pusher design and was only armed with a 6-pounder (57mm) cannon, most likely a Molins M-Class Gun. Compared to its competitors, the Tankbuster was strictly limited to exactly what it was named for; busting tanks, and would find itself having trouble against other ground targets or even defending itself. With the program being canceled in early 1943 and Martin-Baker working on more important projects, all work stopped on developing the Tankbuster any further.

History

Drawing of the Martin-Baker Tankbuster [British Secret Projects]
In early 1942, the Royal Air Force began seeking a new ground-attack aircraft that would replace the 40mm-armed Hawker Hurricane Mk.IID. An order was officially placed on March 7th for a specialized ground attacker that would be used against a multitude of targets including ground units, enemy aircraft, transports/shipping, and a main focus on destroying tanks. To accomplish the destruction of the aforementioned targets, the aircraft was meant to use more heavier guns than the Hurricane Mk.IID. Alternative weapon arrangements included: three 40mm Vickers S cannons, four 20mm Hispano Mk.V cannons, a combination of two 20mm with two 40mm cannons, six unguided rocket (RP) racks with two 20mm cannons or one 47mm Vickers gun with two 20mm cannons. Two 500Ibs bombs could also be added. The expected speed for the design had to reach at least 280mph (450 km/h) at 3,000ft (900 m). Visibility was also a necessity and forward view had to be unobstructed and clear. Full production was to be expected by 1944. The programs would be overseen by the Air Staff.

Over 10 different designs by several aircraft companies were subsequently created for this program. A majority of them were of unorthodox design. Armstrong-Whitworth (AW.49) and Boulton-Paul (P.99) both created twin boom designs. Boulton-Paul also submitted a canard design labelled P.100 and a biplane design labelled P.101, the latter being seen as a safe alternative to the radical canard and twin boom designs prevalent through the program. Perhaps the most interesting of the designs was the submission by Martin-Baker.

3D artist impression of the Tankbuster [candymountain.jp]
At the time of its submission, Martin Baker had been working steadily on their MB.5 project, which would eventually become one of the best performing piston aircraft built by Britain, but this wouldn’t be completed until 1944. Their design for the ground attacker was submitted several months after the order was given by the Air Staff and was only named the “Tankbuster”. Martin Baker’s concept was for a twin boom design that deviated extensively from the given requirements. The aircraft was armed with a single 6-pounder (57mm) cannon, and the aircraft would be completely encased in 1/2-inch armor. The armor itself weighed 4,900Ibs (2,200kg).

The project wasn’t very impressive nor reasonable in the eyes of the Air Staff, especially compared to the other designs in the program. Its single large-caliber gun extremely limited its target range and it would only have been able to attack one of six predicted target types the program requested. The aircraft lacked any other offensive or defensive armament and would rely on its armor alone to protect itself, a gambit that other designs in the program resolved by following the armaments listed by the Air Staff. Attempts to add more ordnance such as additional guns, rockets or bombs to the wings would have added too much stress on the airframe. The main feature of the aircraft was the root of its problems, its gun. The gun itself couldn’t be removed from the airframe and an aircraft going into battle with a single weapon would be inefficient for resources. The Tankbuster didn’t meet the armament expectations and fell under the expected speed by 10mph (16 km a h). On April 15th, 1943, Air Marshall F J Linnell (who was a good friend of James Martin, a founder of the company) advised Martin-Baker to drop development of the Tankbuster in favor of continuing work on the more successful MB.5 project going on at the same time.

Near the later days of April 1943, the Air Staff brought the program the Tankbuster was designed for to an end. They concluded that, at the time, developing and producing an entirely new ground attack aircraft would impede the current war programs and that the submissions were too specialized in design compared to modifying aircraft already being produced for ground attack duties. One such aircraft they pointed to was the Hawker Hurricane Mk IV, a ground attacker version of the famous fighter which was performing successfully in the role and had started production in March of 1943. Later additions to the ground attack role would be the Hawker Typhoon, which became a scourge to German ground troops. Even if the program had continued towards production, it was significantly unlikely the Tankbuster would have been chosen for the role. The aircraft was way too specialized and disliked by the Air Staff, and Martin Baker was working on an aircraft that would yield much better results. Although the Tankbuster may have been the runt of a doomed program, it still proves to be an interesting, albeit flawed solution in the name of destroying enemy armor.

Design

The Martin-Baker Tankbuster was a twin-boom single-engine design. The aircraft would have been constructed entirely of metal. The airframe itself would be covered in an additional 1/2-inch (12.7mm) armor. This armor would weigh 4,900Ibs (2,223kg) on its own. The armor covered the entire body and also the engine cowling. What’s interesting to note is that the aircraft had two engine intakes, one facing forward and one facing the rear. The radiator and oil tank were mounted in the frontal fuselage. The radiator itself was armored by offset plates that would prevent bullets from ricocheting inside. The cockpit area had clear forward visibility, and would seat a single pilot. The canopy would most likely have had bulletproof glass to complement the rest of the armored body. For it’s engine, the Tankbuster would have mounted a Griffon II engine in pusher configuration. This is relevant to Martin-Baker’s other project, the MB.5, as this aircraft also used the Griffon. The reason the aircraft utilized a pusher configuration was it gave the pilot clear visibility in the front and the gun could be placed directly forward. The pusher configuration isn’t common because of the fact that it leaves the engine open to enemies that are chasing the aircraft. This would have been especially deadly for the Tankbuster, given it has no defensive armament. The tail section and wings would also be constructed of metal. The wings were wide to improve low level flight. There was an attempt to diversify the targets by adding additional weapons to the wings, but this would only overload them. The Tankbuster had a fixed tricycle landing gear. This decision was made to conserve interior space but would have slowed the aircraft considerably. The only armament the aircraft would have been armed with would be a 6-pounder cannon (57mm) that would be frontally mounted, supplied with 30 rounds of ammunition. The aircraft would only be allowed to target heavily armored targets. To assist in aiming, the gun was placed towards on horizontal axis. This would prevent the aircraft from pitching when the gun was fired.

Role

The Tankbuster’s design might seem odd by conventional aircraft standards, but every single feature the aircraft had was to assist in it’s role of attacking enemy armor. Long, flat wings would give the aircraft an edge in low-level flight. The pusher engine would give the aircraft a clear view and nothing to obstruct the cannon. The entire airframe being heavily armored would protect against AA fire and enemy aircraft. Going into battle, the Tankbuster would need escort fighters to protect against opposing interceptors. Once in the combat zone, the Tankbuster would begin its assault on enemy tanks. The De Havilland Mosquito also mounted the 6-pounder Molins gun and was also used in the ground-attack role, but only for a short time before switching to an anti-shipping role. It is likely the Tankbuster would have also undergone this change had it entered production.

Variants

  • Martin-Baker “Tankbuster” – The only version of the Tankbuster drawn was the original design with a single cannon.

Operators

  • United Kingdom – This aircraft would have been operated by the Royal Air Force had it been produced.

Martin-Baker Tankbuster Specifications

Wingspan 47 ft 10.8 in / 14.6 m
Length 41 ft / 12.5 m
Wing Area 471.5 ft² / 43.8 m²
Engine 1x 1,730 hp ( 1,290 kW ) Griffon II Inline-Engine
Weights 12,000 Ibs / 5,440 kg
Climb Rate 2,250 feet/min / 686 meters/min
Maximum Speed 270 mph / 434 km/h
Minimum Speed 75 mph / 122 km/h
Crew 1 pilot
Armament
  • 1x 6-pounder (57mm) Molins M-Class cannon

Gallery

Illustration by Haryo Panji https://www.deviantart.com/haryopanji

Scale model of the Tankbuster [modelingmadness.com]

Sources