A.Brew Boulton Paul Aircraft since 1915 (Putnam)

P.3 Bobolink

   With Boulton & Paul producing large numbers of Sopwith Camels, it was logical that John North should take an immediate interest in producing a Camel replacement, for which the Air Ministry had issued the official Specification A.1A. North began to urgently consider several layouts. The engine designated by the Air Ministry for use in the A.1A contenders was the 230 hp Bentley B.R.2 rotary, which was only 93 lb heavier than the 150 hp B.R.1. A second clutch of designs was built around the compact 170 hp ABC Wasp radial, the Sopwith 8F.l Snail, the Westland Wagtail and the BAT FK.22/2 Bantam.
   Sopwith's entry in the design competition was the Snipe, which was some way ahead of its competitors, first flying late in 1917, powered by a B.R.l, as the larger engine was not yet available. It began life as a single-bay design, with a slab-sided fuselage, with two prototypes of slightly differing layouts being evaluated in December 1917. The third prototype was converted to a two-bay layout with a rounded fuselage, being delivered to Martlesham Heath fitted with one of the first B.R.2s in February 1918.
   Although the Snipe represented the main competition, there were also two other important contenders for the Camel-replacement order, the Austin A.F.T.3 Osprey triplane, designed by North's successor at Austin, John Kenworthy, along with C H Brooks; and the Nieuport BN.1, Henry Folland's first design for the British Nieuport company, and owing much to his earlier design, the S.E.5A.
   Boulton & Paul were awarded orders on 1 December, 1918, for two of their layouts, the P.3 and the P.5. Three prototypes were ordered for each design, the earlier set of serials, C8652-C8654, going to the P.5, and the later ones, C8655-C8657, to the P.3. The company bestowed the name Hawk on the P.5, though it may well have also been used for the P.3, but were forced to change it because of an Air Ministry nomenclature system which came into effect in 1918.
   The names of birds of prey were reserved for aero-engines, (the Hawk being a Rolls-Royce engine), and single-seat single-engined landplanes were to be named after land-birds, other than birds of prey, or reptiles. In addition Boulton & Paul were awarded the initial letters BO. (Sopwith were awarded the initial letters SO, SA and SN-hence the name Snipe, and Austin were awarded AU, AS or OS - hence Osprey.) Boulton & Paul chose to rename their entry Boblink, later to be changed to Bobolink, which is a North American bird.
   The P.5 was abandoned at an early stage and the serial numbers were re-allocated to other aircraft, but construction of the first P.3 went ahead with some urgency, to ready it for trials against the other three contenders at Martlesham Heath. Availability of the B.R.2 was as much a constraining factor as construction of the aircraft, and the first P.3 Bobolink, C8655, was eventually fitted with only the fourth B.R.2 built.
   Like the revised Snipe it was a two-bay design with equal-span wings with 2 ft 31/2 in stagger. They featured N struts, which were still an unusual feature, though they had been used by North before the War on the Grahame-White Type 13. Their advantage was that they simplified rigging. The structure was a conventional wooden one, with fabric covering. The wings were very light, the lower ones, without their fabric covering weighed only 29 lb, a tribute to North's design, and Boulton & Paul craftsmanship. To begin with ailerons were only fitted on the upper wings, but a lack of manoeuvrability shown in early trials at Mousehold caused strut-linked ailerons to be fitted to the lower wings. There was a large rectangular cut-out in the upper wing to give the pilot excellent upper hemisphere vision.
   Of necessity the front fuselage was of circular section to accommodate the rotary engine, but the aft fuselage was flat-sided, made up of a simple wire-braced box-girder, with a curved upper section behind the pilot's head. One feature displayed the clever thinking and careful design which were to become associated with North. These were the two fuel tanks, of 34 and 6 gal, placed behind the pilot, with an armour plate between them, so that one bullet would have little chance of damaging both. In case they caught fire, both tanks could be jettisoned in flight so that the pilot could glide safely to a landing, saving the rest of his aircraft. In the days when pilots were still not being allowed to wear parachutes in highly inflammable wood and fabric aircraft, this was a very clever idea.
   The tail had a sharply-swept leading edge running to a curved fin. Overall length of the aircraft was 20 ft, span was 29 ft, and the height was 8 ft 4 in. In comparison the third prototype Snipe had 2 ft 1 in greater span, 1 ft 2 in more height, but was 9 in shorter.
   Two Vickers machine-guns were fitted on the forward fuselage, firing through the 9 ft diameter arc of the two-blade propeller, and provision was made for a Lewis gun on a rail on the upper wing. When C8655 was rolled out of Riverside Works in December 1917, complete except for the front fuselage covering, this rail and Lewis gun were actually fitted, as well as the twin Vickers guns. Before delivery for evaluation the Lewis mounting was removed however. As might be expected the engine mounts and Vickers installation were very similar to those of the Camel.
   Capt Frank Courtney undertook the company's initial flight trials at Mousehold. He had been transferred from training to RFC experimental flying and was engaged in the programme to fit 150 hp Monosoupape engines to Sopwith Camels for the Americans. Flight testing for this programme was undertaken at Mousehold on Boulton & Paul-built Camels, so it was natural that, as an experienced test pilot, he should give the Bobolink its first flights.
   As well as finding fault with its manoeuvrability, which caused the ailerons to be fitted to the lower wings, Courtney also criticised the Bobolink for the narrow track of its undercarriage, which made taxi-ing difficult, though he felt it was not so serious a fault as to warrant any immediate change. The propeller fitted when the aircraft was first rolled out at Riverside had markedly square-cut tips, but all later pictures of it show conventionally rounded tips, probably the Snipe propeller with which it was fitted at Martlesham.
   Delivery of C8655 to Martlesham Heath was made in the week ending 9 March, 1918, where it joined the Snipe. The Nieuport BN.1 and Austin Osprey were delivered in the same week, and flying evaluations were undertaken as a matter of urgency. As a final test a number of Service pilots, including Capt James McCudden were invited to evaluate the four aircraft in a day's trials at Sutton's Farm.
   Each of the machines was tested with a Snipe propeller and a full specification load ie 40 gal of fuel, 8 gal of oil, 150 lb of Vickers guns and ammunition, 50 lb of Lewis gun and ammunition and 25 lb of electrical clothing and oxygen. Because of a breakage of its cowling no reliable performance trials could be made on the Nieuport.
   The Osprey with its 23 ft wingspan was easily the most manoeuvrable, followed by the Nieuport, with the Bobolink the least favoured because of heavy handling and slow lateral reaction. The Osprey was clearly the slowest of the four; the short era of the triplane was really over. It had not in fact been granted an official order, but was built as a private venture, with special permission from the Air Ministry under Licence No.17, and awarded the serial X.15 in a special series reserved for such private-venture aircraft. The BN.l was a two-bay design like the Bobolink and Snipe, but featured revolutionary I struts, which were looked on with suspicion. It was the fastest of the four aircraft, with a very promising all-round performance, but on 10 March it suffered an unfortunate accident, catching fire in the air, and was completely destroyed, ruling it out of the contest, as a second prototype was not immediately available.
   The view from the pilot's seat was best in the Snipe, followed by the Nieuport and the Bobolink, though with small alterations all three would be very similar in this respect. The Osprey was very much poorer, and there was no easy way to improve the pilot s view. As far as accessibility to engines and accessories were concerned, the Osprey was clearly the best, followed by the Snipe and the Bobolink, which were much on a par. The Nieuport was much the worst of the four, though alterations could improve to the standard of the other two biplanes.
   The Vickers guns were equally well sited on the biplanes, but the crank handles were difficult to reach on the Osprey. The Lewis gun was difficult to use on the Bobolink and Snipe, as the pilot sat too near the rear spar, the Nieuport being much better in this respect. The Lewis gun was impossible to fit on the Osprey, except in a fixed vertical mounting.
   The Applied Design Branch submitted a report on the ease of production and maintenance of the four aircraft. The Osprey and Nieuport were considered the best, though the design of the Nieuport's wings was criticised. The Bobolink was described as very bad from the production and maintenance point of view. This view does seem strange as the Bobolink had such a simple rectangular box-girder fuselage, whereas the Snipe for instance had a complicated rounded fuselage made up of formers and stringers.
   There was little to choose between the four aircraft, though the greater experience of the Sopwith company, and the fact that the Snipe had been flying for some time, and had already had fundamental changes to its design, weighed heavily in its favour. Although its top speed was disappointing, (121 mph at 10,000 ft, 4 mph slower than the Bobolink), its rate of climb was magnificent, and its handling at altitude was excellent, feeling like a well-behaved Camel in the air.
   Taking all factors into account the following order of merit was arrived at 1. Snipe, 2. Nieuport, 3. Osprey, 4. Bobolink.
   Perhaps inevitably the Snipe was chosen, even though the Bobolink displayed a fractional edge in overall performance. Some of the other criticisms of the Bobolink were the narrow track of its undercarriage, and, though this could presumably have been cured, the poor access to the cockpit, which was set well within the cut-out of the upper wing.
   The Bobolink was later fitted with a larger horn-balanced rudder to try to cure the ground-handling difficulties, the horn balance being unshielded, looking rather incongruous above the unchanged fin. The strut connection of the ailerons was also changed, being replaced by cable links. The Snipe too required a larger rudder, increasing its length to 19 ft 10 in.
   Another B.R.2 powered fighter appeared later in the year, the Armstrong Whitworth Armadillo. By the time it flew there was no chance of it being ordered, but its details are included in the following comparison of the various contenders for completeness.

Performance and Dimensional Comparisons

   Bobolink Snipe Osprey Nieuport BN.1 Armadillo
Speed at 10,000 ft 125 mph 121 mph 118 1/2 mph 127 mph 113 mph
Climb to 6,500 ft 5 min 20 sec 4 min 55 sec 5 min 30 sec n/a 6 min 30 sec
Climb to 10,000 ft 9 min 20 sec 8 min 50 sec 10 min 20 sec n/a n/a
Climb to 15,000 ft 18 min 17 min 40 sec 21 min 20 sec 16 min n/a
Service Ceiling 19,500ft 19,500ft 19,000 ft 26,000 ft 24,000 ft
Endurance 3 1/4 hr 2 1/4 hr 3 hr 3 hr 2 3/4 hr
Span 29 ft 31 ft 1 in 23 ft 28 ft 27 ft 9 in
Length 20 ft 19 ft 3 in 17 ft 7 in 18 ft 6 in 18 ft 10 in
Height 8 ft 4 in 9 ft 6 in 10 ft 8 in 9 ft 7 ft 10 in
Loaded Weight 1,992 lb 1,964 lb 1,888 lb 2,030 lb 1,860 lb

   The Snipe was ordered in large numbers', including an initial 400 from Boulton & Paul, which must have been a bitter pill for John North to swallow. The other two Bobolink prototypes, C8656 and C8657 were cancelled on 9 April, though the fact that the serials were not re-issued may indicate that the construction of these two aircraft was well advanced.
   The sole Bobolink was delivered to RNAS Hendon on 18 June for assessment as a shipboard fighter, though it was sent to Norwich the following day, for three days, possibly for modifications. It returned to Hendon on the 21st, and then returned to Norwich on 22 July, where presumably it ended its days.

P.3 Bobolink
   230 hp Bentley B.R.2.
   Span 29 ft; length 20 ft; height 8 ft 4in; wing area 266 sq ft.
   Empty weight 1,226 lb; loaded weight 1,992 lb.
   Maximum speed 125 mph at 15,000 ft; climb to 6,500 ft 5min 20 sec, to 10,000 ft 9 min 20 sec, to 15,000 ft 18 min; service ceiling 19,500 ft; endurance 3 1/4 hr at 15,000 ft.
   Armament: two forward-firing Vickers machine-guns; provision for Lewis gun on universal joint mounting on upper wing.