FLIGHT TEST Displaying a Sopwith
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> FLIGHT TEST WORDS Francis Donaldson RFC REALITY IN A WW1 SCOUT Displaying a Sopwith Pup replica with the Great War Display Team 30 LIGHT AVIATION JANUARY 2011 p032-040.flighttestV2FINAL.indd 48 21/12/10 19:23:28 RFC REALITY IN A WW1 SCOUT Displaying a Sopwith Pup replica with the Great War Display Team JANUARY 2011 LIGHT AVIATION 31 p032-040.flighttestV2FINAL.indd 49 21/12/10 19:23:32 > FLIGHT TEST READ any account by a First World War pilot of the Royal Flying Corp who lived through the 1917-18 period, and the Le Rhone rotary powered Sopwith Pup always seems to be quoted as the most delightful to fly of all the scouts of that era. Not the best warplane, for by the time it was in widespread service its performance and firepower were inferior to contemporary opposition like the Albatross - but the Pup was dainty, willing, joyful – ‘you could do anything with it’. Later Sopwith models like the Camel and Snipe were more powerful and militarily effective but more vicious in their characteristics, whereas the government- designed SE5 was fast and a brilliant gun- platform but lacked the Pup’s sparkle. Not surprising then that when I happened to be in the right place at the right time to experience a replica Pup, albeit radial powered rather than rotary, I was quick to take up the offer. G-BZND was built as an LAA project by Brendan Goddard in the Southampton area. Started in 1989, Brendan built the aircraft in a very modest lean-to workshop at the back of his house, under the supervision of local PFA inspector and vintage aircraft guru Ron Souch. The aircraft was built from the ‘Replicraft’ drawings, which are tracings of the original Sopwith blueprints, re-formatted onto a few large sheets and primarily intended for use by model makers. To complete any plans-built project is a massive achievement and that Brendan built such a complicated craft as the Pup in such minimal facilities was outstanding. Wood and fabric aircraft of the First World War era With a speed were not designed with simplicity of build differential of only 5-10 as a priority. Unsure of the reliability of the knots, it’s hard to catch glues of the period, Sopwith’s aircraft used your prey if you mis- wooden members held together by complex jdge the ‘pounce’. metal fittings folded from flat mild steel sheet, bolts, rivets and piano wire bracing wires, tie rods and compression struts, all tensioned up by literally dozens of turnbuckles – a labour- horsepower at 2550rpm, which at first sight wife, Mary, was determined to see the aircraft intensive form of construction that was to seemed a suitable more modern (1940s) airborne and displayed before the public in be rendered obsolete a decade later by de substitute for the 80 horsepower Le Rhone Brendan’s memory. Havilland’s brilliantly simple glued together rotary fitted to the originals. Mary was introduced to Sopwith aficionado ply-covered wooden box fuselage. Things are not always how they seem Ernie Hoblyn, who had rebuilt a Sopwith A stickler for realism, Brendan wasn’t however, and when the Pup was assembled for Triplane a few years previously along with one to make his replica with a welded steel initial taxi trials at a strip near Brendan’s home, LAA inspector Dave Silsbury, and had been tube fuselage, like so many of the American the Salmson clearly couldn’t cut the mustard, flying it for many years with the Great War WW1 replicas – he built the whole thing in for it could scarcely get the Pup moving at a Display Team. The Pup was dismantled and the original Sopwith fashion. Not letting fast trot, let alone up to take-off speed. The moved to Ernie’s home field at Watchford standards slip as he neared the end of the problem, predictably, was that not helped by Farm whereupon, acting on Mary’s behalf, he job, he even spliced and whipped the ends of the masking effect of the big radial cowl, 80 extracted the feeble Salmson and re-engined it all the stranded steel external bracing wires horsepower turning a relatively small diameter with a 145 horsepower Warner Scarab, turning in the original manner, rather than swaging propeller at 2200rpm or so was a lot less a 90-inch propeller. them. Likewise, all the fabric rib tapes were effective in producing thrust than the original After having the new engine mount painstakingly frayed-edged rather than pinked. 100-inch diameter prop turned by the Le Rhone stressed by a local ex-Westlands stress man, a Save for the use of modern glues and metals, at 1200rpm. sometimes frustrating exchange of paperwork AN hardware, synthetic covering and paints, Tragically, Brendan passed away shortly and a couple of visits by LAA Engineering’s firewall aft, Brendan’s Pup is pure Sopwith. after, with the aircraft complete but unflown design team, the aircraft was finally cleared The project was completed in 2000, the and unflyable. At this point, the aircraft could for flight in December 2005. It was test flown main concession to modernity being the use so easily have been relegated to a static role initially by Ernie from nearby Bodmin and then of a Salmson 5AQ radial engine rated at 90 in some museum but fortunately Brendan’s by Dan Griffith who had been invited to display 32 LIGHT AVIATION JANUARY 2011 p032-040.flighttestV2FINAL.indd 50 21/12/10 19:23:35 the aircraft for Mary. portion to the rear of the cockpit. Every bay of With the Scarab engine, the Pup was ‘With the Scarab engine, the fuselage is braced by criss-crossing piano transformed – now it would leap off the ground the Pup was transformed wires taughtened by turnbuckles, and the eagerly and climb away in a very spritely front end is reinforced with large pressed steel fashion. With a Permit to Fly issued by LAA in – now it would leap off frames and wood diagonal struts that would August of 2006, at last the Pup would be able to have originally have provided the mounting for be displayed for the enjoyment of the public, the ground’ the fixed crankshaft that projects from the rear as Brendan had always intended. The Pup of a rotary engine. remained Watchford-based, but with Ernie The undercarriage consists of a pair of usually at the controls of his Sopwith Triplane the Pup was being designed in late 1915. streamlined steel tube V-struts - in the replica it was my great good fortune to be invited to act While in this period the Germans were more built from Piper Cub lift strut material, suitably as reserve display pilot on the Pup, to take part boldly experimenting with cantilever wings, reinforced, a tie bar assembly and two half- when Dan was otherwise committed. and fuselages of stressed-skin wood or welded axles, the whole lot being wire-braced. The steel tube, and even all-metal corrugated bungee-sprung half-axles carry big spoked CONSTRUCTION METHODS construction, British manufacturers clung to wheels built up on specially made hubs, The Pup’s airframe is typical of allied biplanes the wire-braced wood formula well into the with motorcycle rims. The tail surfaces are of the period, consisting basically of two wire- 1920s and beyond. conventional WW1 wire-braced, without the braced wood-framed box girders set at right The outside contours of the square-box benefit of trim, horn balance or other latter- angles – the one being the fuselage, the other fuselage frame are fleshed out with lightweight day indulgences. The wooden tailplane and the boxkite-like wing cellule. This form of plywood formers and pencil-thin stringers elevators are reassuringly large, suggesting construction, first seen on the French Goupy II which make up the upper turtledeck and blend good longitudinal control, but the squat fin and biplane of 1908, had fully matured by the time the rounded sides at the firewall into the flat rudder seem woefully small – more later. JANUARY 2011 LIGHT AVIATION 33 p032-040.flighttestV2FINAL.indd 51 21/12/10 19:23:38 > FLIGHT TEST Nigel Hitchman PHOTO Walking up to the Pup, whilst its 26-foot span is three feet less than a Tiger Moth’s, overall the Pup seems a bigger machine to modern-day eyes, perhaps because of the bulkier fuselage, snub-nose and tall undercarriage. The tips of the noticeably dihedralled wings are almost ten feet above the ground higher, surprisingly, than the contemporary Fokker Triplane. The broad-chord wings present a huge area of fabric to the breeze – 254 square feet of it in fact, about 10% more than a Tiger Moth in an airframe that has more power. The Pup’s fully loaded weight, at 1250lb, is hardly more than the empty weight of De Havilland’s famous trainer making the Pup’s wing loading on a par with the wispiest of microlights. The pre-flight includes checking that the bottom spark plugs of the Warner are present, tight and connected. After the aircraft has been out of use for a while, to prevent any risk of the dreaded hydraulic lock it’s a good idea to remove these plugs to drain off any accumulation of lubricating oil, so we need to make sure they’ve been put back. Otherwise, as with any vintage machine it’s a regular walk-around paying particular attention to any signs of leaks, cracks, slack This striving for self-sufficiency in your optimum ‘ten past eight’ or ‘ten to four’ angle fabric, loose cables, broken locking wire and biplane gives you a feeling of kinship with for a comfortable ‘pull through’, depending so on.