Britain hoped to take the airspeed record back from Germany with the Napier-Heston T.5, but it literally fell flat on its first flight.
In 1935 the British engine manufacturer D. Napier and Son came out with an extremely advanced, hugely complex, high-revving and unusually powerful aircraft engine, the Napier Sabre. This 24-cylinder, 2,450-hp, H-configuration power plant was essentially two flat, horizontally opposed 12s stacked one atop the other (imagine a sandwich of two Porsche 917 engines, but liquid-cooled), each with its own crankshaft. The two cranks were geared together at the nose to drive a single prop shaft through reduction gearing.
The British knew the Germans would soon be tackling the world unlimited airspeed record with an advanced engine that Daimler-Benz had developed— the DB 601 V12—for there was substantial friendly interchange between Daimler and Rolls-Royce. In that era, the Third Reich still viewed the English as Germans who spoke the wrong language. In 1934 the record stood at 440.6 mph, held by Italy and established by the fearsomely dangerous Macchi-Castoldi M.C.72 floatplane powered by a 24-cylinder Fiat AS.6.
Napier decided to develop a dedicated top-speed, Sabre-powered landplane to take back the record when—not if—the Luftwaffe set one. Or ideally to set the bar high enough that all challenges would fall short. Napier was even said to be eyeing the 500- mph barrier, the aviation equivalent of the four-minute mile. In any case, the resulting airplane was called the Napier-Heston T.5: Napier for the power plant, of course; Hes – ton for the small English aircraft company selected to engineer and build the airframe; and T.5 for Type Five, since it was only the fifth type that Heston had ever built.
Heston was selected not because the firm was an experienced manufacturer of high-performance planes—it actually built only lightplanes—but at least in part because it was viewed as a company of trusty woodworkers, and the T.5 would be built of wood. Far from being an old-fashioned aviation material, wood has been called “God’s own composite” because it has many of the properties of advanced plastic materials. It’s light, extremely strong for its weight, is immune to fatigue failure, can be coaxed into compound curves with the help of steam and molds, can easily serve simultaneously as structure and skin (monocoque), and if properly coated and protected will last virtually forever. The absence of rivets and butt joints—wooden skins are “scarfed” where they come together, forming very shallow mating angles that create virtually invisible seams—meant wood was the lowest-drag aircraft skin available in the late 1930s. The Napier-Heston would be further finished with 20 coats of hand-rubbed lacquer for an absolute minimum of parasitic drag, and in critical areas such as the wing leading edges, it was said that any scratch deeper than five ten-thousandths (0.0005) of an inch was polished out.
Despite the company’s lack of experience with high-performance airplanes, Heston’s chief designer George Cornwall did much of the detail design on the T.5. Some of the most innovative work, however, was done by Napier’s Arthur Hagg, a highly regarded ex–de Havilland engineer whose specialty was very low drag ducting of engine induction and cooling air, which would be a major feature of the Napier-Heston’s design. Creating the T.5 in the first place was, in fact, Hagg’s idea.
The Napier-Heston was the first highspeed airplane to have a mid-fuselage belly airscoop, a design feature that was soon to become the bull’s-scrotum hallmark of the P-51 Mustang. The T.5’s cooler was somewhat more complex than the Mustang’s, however. A separate duct at the front of the main cooling scoop bled off most of the turbulent boundary-layer air that flowed aft under the airplane’s fuselage, thus reducing drag and smoothing airflow into the cooling duct just behind it. Both the exhausted boundary-layer air and the cooling air that passed through the twinned oil and glycol belly radiators exited not at the rear of the scoop but traveled all the way aft, alongside the cockpit on either side, to D-shaped exhaust ducts bracketing the rudder post, just below the horizontal stabilizer.
The Napier-Heston also had a tiny one-piece, frameless, blown-Perspex canopy of a type that wouldn’t be seen again until the fastest unlimited Reno racers began using them in the 1960s. It was sealed by a rubber gasket after the pilot put it on like a plastic hat and latched it from the inside, and was slightly pressurized by ram air.
Much like the barrel-shaped Gee Bee R-1 racer, the T.5 truly was little more than an engine with wings. Gross weight of the entire airplane was 7,200 pounds, of which about 2,900 pounds was the massive engine—40 percent of the total. As a comparison, a loaded P-51D Mustang weighs 9,200 pounds, of which 1,645 pounds, or 18 percent, is the Packard Merlin engine. One widespread Napier-Heston myth has the Sabre super-tuned for an output of 4,000 hp, a wild exaggeration. The racer’s engine was actually boosted to 2,650 hp for the planned record attempt.
A typically English facet of the Napier-Heston project was that, like the Schneider Cup racers, the Bristol Blenheim and several other important airframe projects, it was privately funded rather than a government- or industry-supported affair. Britain’s Air Ministry understandably said that it had no intention of spending public funds on such an extreme and risky testbed for an already complex new engine’s first flights. Therefore the banker behind the Napier-Heston was the patriotic Lord Nuffield, born Robert Morris, who had made his fortune building Morris automobiles. Lord Nuffield did not want to see the world airspeed record move to Germany, particularly after Britain’s Schneider Cup triumphs.
Though the Napier-Heston was designed and built with a short career in mind—set the record and retire—nobody had counted on the airplane logging a total of only six minutes of flight time. Cautious ground running and taxi tests consumed more than six months. Finally, on June 12, 1940, with World War II already well underway, everything seemed just right for G.L.G. Richmond, an RAF squadron leader who also worked as Heston’s chief test pilot, to take the T.5 up for its first flight. It was 14 months since Germany had set a new world record of 469.22 mph with the Messerschmitt Me-209 V-1, but the Napier-Heston was gunning for possibly 480.
Five minutes after takeoff, the liquid-cooled engine was severely overheating, Richmond was having pitch-control problems with the overly sensitive controls and he was being scalded by steam from a broken fitting on the radiator under his seat. To complicate matters, he had chosen to make the first flight without the claustrophobic canopy, which left him with not even a windscreen. He flew a wide but hasty 200-mph pattern and tried to set the airplane up for its first-ever landing without having the faintest idea what its best-approach or stall speeds might be.
Flying an experimental high-speed, near-laminar airfoil, he unfortunately discovered an approach to that stall speed while still 30—some witnesses say 20—feet over the Heston factory’s grass runway. The T.5 pancaked in hard enough to drive the landing gear completely through the wings, breaking off the entire tail and doing enough damage to make the airplane a total write-off. The Napier-Heston would never fly again, and a partially completed second airframe was subsequently scrapped. Badly burned but alive, Richmond was doubtless embarrassed and never heard from again.
Exactly a month from that day the Battle of Britain would begin, and the British had more important things to worry about than airspeed records.
Originally published in the July 2010 issue of Aviation History. To subscribe, click here.
