Following the cancellation of the Bobolink project, Boulton & Paul’s design department began work on a full-scale experimental aircraft, with wing drawings dated April 14, 1918. At the time, creating such an aircraft was a rather unusual step, considering that most pioneering aircraft could be considered full-scale experimental machines, as their creators could not definitively state whether or how their creation would fly before its maiden flight. John North’s meticulous approach demonstrated his intent to enhance the company’s design capabilities.
Since the Defence Regulations introduced in 1917 prohibited building aircraft without official sanction, permission had to be obtained for the construction of the P.6. The machine was registered in the special “X” series, reserved for such aircraft, and received the serial number X.25 – the last one issued.
Experimental Design and Purpose
The P.6 was a conventional wooden-and-fabric two-seater biplane, primarily designed to study various wing sections. The development of this machine was part of Boulton & Paul’s main program of systematic research. Having a full-sized aircraft proved highly beneficial for eliminating scaling errors found in wind tunnel test results.
The wings were single-strutted, of equal span, and featured the RAF 15 primary airfoil. The chord and interplane gap, both 5 feet (1.52 m) long, were substantial compared to the 25-foot (7.62 m) wingspan. The front cockpit was located beneath the center section of the upper wing. The wings had spruce spars and ribs, a spruce leading edge, and an ash trailing edge. Ailerons were fitted to both upper and lower wings, with an area of 7.5 sq ft (0.7 m²).
The fuselage incorporated a large number of parts from the Sopwith Camel fighter and shared a similar box-section construction with a slightly curved upper surface. The use of Camel parts was expected, as the company manufactured these aircraft at a rate of 29 machines per week. The engine cowling was metal and remained unpainted. The very rounded rudder had an area of 9 sq ft (0.84 m²) compared to the two square feet (0.19 m²) of the fin.
Technical Specifications and Performance
The P.6 was powered by an eight-cylinder, air-cooled RAF 1a V-engine, driving a four-bladed propeller 9 feet 3 inches (2.82 m) in diameter. This powerplant propelled the P.6 to 103 mph (165.7 km/h) at an altitude of 1,000 feet (304.8 m), while a 20.1-gallon (91.38 L) fuel tank provided an endurance of 2 hours and 20 minutes.
The date of the P.6’s first flight is unknown, but it likely occurred in late 1918, as the Snipe replaced its predecessor, the Camel, on the assembly line in November, and Camel parts were used in the experimental machine. It is highly probable that Frank Courtney made the first flight. He subsequently performed several more flights, after which Mrs. Dawson Paul first flew the P.6 in March 1919.
Transition to Civil Use and First Business Flight
It is not known whether the main lifting surfaces actually installed on the aircraft were interchangeable, but a large volume of experimental data was collected during the P.6’s operation. The P.6 was a well-handling light aircraft; in addition to gathering experimental data, the company aimed for financial gain: after the war, the machine was offered for sale at £600 and served as a prototype for the larger P.9 version (Boulton & Paul anticipated a post-war civil aviation boom and intended to fully capitalize on it).
The company’s commercial director put the P.6 into service as a transport aircraft, registering it on May 20, 1919, and obtaining the civil registration K-120/G-EACJ. However, there are some doubts about the application of the civil registration number, as all surviving photographs of the aircraft show it retaining the serial number X.25 and Royal Air Force roundels. Large letters on the sides of the fuselage, reading “Boulton & Paul Ltd, Sales Dept,” served as an early form of aerial advertising.
The machine became one of the first corporate aircraft, credited with the honor of the first business flight from Norwich to Bury St Edmunds, which took place on May 1, 1919.
Technical Specifications
| Modification | P.6 |
| Wingspan, m | 7. 62 |
| Length, m | 5. 79 |
| Height, m | 2.44 |
| Wing area, m2 | 21.83 |
| Empty weight | 499 |
| Maximum takeoff weight | 782 |
| Engine type | 1 Piston engine RAF 1a |
| Power, hp | 1 x 90 |
| Maximum speed, km/h | 166 |
| Cruising speed, km/h | 136 |
| Flight endurance, h.min | 2.20 |
| Rate of climb, m/min | 169 |
| Crew, crew members | 1-2 |
Image and diagram gallery of the P.6
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