If you wanted to study aerodynamics, you would only have to look at early aircraft designs, like the Bleriot XI. There are no high-bypass-ratio turbofans, no upper-deck lounges, and no global positioning systems. Instead, the aircraft is a pure expression of the design solutions required to overcome the four forces of flight: lift, weight, thrust and drag. One such “studio” can be conducted at Cole Palen’s Old Rhinebeck Airfield in Rhinebeck, New York.
The culmination of ten previous configurations built by Louis Bleriot, who reinvested 60,000 French francs accumulated during a car lamp manufacturing venture to develop a technologically successful aircraft in a career with names like the Wright brothers, Henri Farman, Santos Dumont and Glenn Curtiss. , the Bleriot XI itself had become the world’s first practical monoplane.
The Bleriot VII, which provided its initial base, appeared with a partially enclosed fuselage to house its sole pilot; wings braced to a tubular cabin frame above the cabin; a 50-hp four-blade Antoinette engine; a broad horizontal tail with two alveoli; a small rudder; and swivel wheels with independent suspension. Although it crashed on December 18, 1907, it laid the foundation for a later definitive design.
The Bleriot VIII, which quickly followed, had retained the low-wing configuration, but featured pivoting ailerons on the wingtips and tricycle landing gear, each consisting of individual wheels.
Although the Bleriot IX had been a larger variant of the VIII, and the Bleriot X had introduced a propeller-drive arrangement with triple canard rudders, these intermediate steps had offered little to the final design and had therefore been quickly discarded. That last design had taken the form of the Bleriot XI.
Its long, tapering fuselage, made up of ash spars, spruce struts, and crossmembers held together by wire trusses, was light but strong, providing the common attachment point for its airfoils and engine. Only half covered by cloth, it looked primitive and unfinished, but functional.
The cloth-covered, ribbed wings with rounded tips featured a span of 28.2 feet and an area of 151 square feet and were attached to the fuselage at an angle, offering a considerable dihedral. The curvature of the upper surface and the sharply raked leading edge were in themselves expressions of aerodynamics. Guided closely by their upper surfaces, the airflow is tilted down and past their trailing edges, reducing upper surface pressure, increasing airflow velocity, and causing the airfoil to “react” on the airfoil. support principle. High-lift devices such as slats and flaps had not been included, not even ailerons. Instead, lateral control had been provided by the Wright brothers’ designed wing-crumple method, an inverted turret attached below the fuselage that provided a wire connection for the crumple actuators. By differentially rotating the entire wing, they transformed it into a huge aileron, increasing its angle of incidence and inducing roll in flight.
A 16-square-foot, rectangular-shaped stabilizer, mounted below the conical structure toward the end, provided deflection for pitch axis control, while a fully-moving 4.5-square-foot rudder, apparently minuscule for the aircraft, provided yaw control. at the far end of the fuselage.
A 35hp, inverted-Y, air-cooled, three-cylinder Anzani engine, which replaced the design’s original 30hp REP engine and attached to an ash front frame, drove a mahogany, scitmar-shaped engine, of 6.87 feet. diameter propeller at 1,350 rpm. Due to the then-inadequate power capacity of the existing engines, the Bleriot XI, like all early designs, had struggled with power-to-weight ratios, its designers having been forced to use strong but lightweight wood for the frames and fabric for the wings. aerodynamic surfaces.
The smooth, finely sanded, intricately shaped propeller had been a combination of artwork carving and streamlined expression. Essentially, a tiny wing, rotating perpendicular to the flight path, developed thrust in the same way that a wing created lift, the relative wind hitting it in its plane of rotation. Because it had been positioned at an angle of attack, and because it had a cambered airfoil, it developed lift in the forward direction, redefined here as “thrust”, the “twisting” of the propeller allowed it to retain thrust. same angle of inclination. -attacks along its radius with its pitch angle high near its center, but low near its edge.
The ash front frame had also provided the attachment point for two of the aircraft’s three fine-spoke swivel wheels, whose periodic wraps of tape ensured adhesion between tire and rim. The unique swivel capability of the landing gear, which traces its origins to the Bleriot VII, allowed the aircraft to operate more adequately during crosswind field conditions, as the tiny rudder had not offered sufficient area to counteract this in a appreciable degree and the whole had been too fragile. to structurally support lateral loads. As a result, he had been able to track the ground at an angle.
The cabin, made up of a wooden frame and rubber cloth on its sides, featured the Bleriot-designed control system in which a small circular non-rotating wheel had been mounted on a vertical post that was based on a round metal. Half-dome “cloche”, or “bell” in French, to which the two front and rear elevon drive cables and two lateral wing-warping cables had been attached. The surfaces had been moved by throwing the club forward, backward, or to either side. The “sophistication” of the cockpit had been completed with an engine throttle on the right side and two instruments: a compass and a fuel quantity indicator.
A small barrel-shaped fuel tank had been installed horizontally between the engine and the cockpit.
The Bleriot XI, powered by the 35-hp Anzani engine, featured a gross weight of 661 pounds and could reach speeds of 47 mph.
First flying on March 15, 1909, with the earlier REP engine, it had only jumped a distance of 8,200 feet, but this inauspicious start had hardly been indicative of the performance and success of the design, for just four months later, the On 25 July, he had made the first flight across the English Channel, a record-breaking 25-mile flight from Calais, France, to Dover, England, winning the Daily Mail’s £1,000 prize for the feat. The landmark event, which generated worldwide attention, sparked an influx of orders for the type.
The design, low power, and minimal effective surfaces of the Bleriot XI dictate its operation. The brakeless plane, for example, can only be directionally controlled by its tiny rudder on the ground. Takeoff, due to the high angle of incidence of the wing, is best achieved with full cloche advance, or throttle, which raises the tail to a position parallel to the ground and places the entire weight of the aircraft on its main wheels, while Wind-induced track angles can be partly or fully counteracted by rudder deflections, depending on their degree, and her rotating landing gear further increases this. Thus profiled, the aircraft is induced into a shallow climb. The camber and area of the wing, along with ground effect, temporarily help with this, but it still has steep stall characteristics.
The stepped climb profile, dictated not by air traffic control restrictions, but by speed requirements, generates lift at each “plateau.”
Although the full throttle setting must retain maximum flow over the engine to meet its “air-cooled” requirements, the slow and brittle design is susceptible to wind gusts, and the slopes must be shallow and soft. There is not enough power available to counteract turns of 30 degrees or more that exponentially increase wing loading and inevitably lead to stalls. Lateral control of wing roll is minimal and slow.
Full power nose-down descents are ideally stopped with throttle reductions just before the wheels hit the ground. The above power reductions are, due to insufficient engine power, unstoppable, and pre-landing flare will force the airframe onto its tail skid.
The Old Rhinebeck Aerodrome Bleriot XI, build #56, is the oldest airframe still in flight in the US, eclipsed only by the Shuttleworth Collection Bleriot, which carries build #14 .
Having crashed during a 1910 air rally at Sauguss, Massachusetts, the Rhinebeck example was subsequently purchased by Professor HH Caburn, who had passed it around daily while cycling to work and stored it, until it was delivered to him. to Bill Champlin. from Laconia, New Hampshire. Later donated to Cole Palen in 1952, it lacked its engine and airfoils, but its front and rear thirds were complete. Two years later, in October, newly built wings, horizontal stabilizer, and rudder were installed at Stormville Airport.
Due to the aircraft’s fragility, it is restricted to “short hops” from Old Rhinebeck’s rolling grass field during Saturday’s “History of Flight” air shows, having reached only a maximum altitude of 60 feet. However, this short leap of elegantly simple aerodynamic expression traces its origin to, and thus represents, the then “long haul” across the English Channel that the original Bleriot XI had made a century ago as the first practical monoplane. of the world and predecessor of all modern aircraft that now routinely connect the world.
