Flying Qualities of the Reproduction Flyer

by Dr. Richard Stimson

in Inventing The Airplane

A reproduction of the 1903 Wright Flyer built by the Wright Experience (WE) made two successful flights at the Wrights Brothers National Memorial Park in December 1903. The flight on Nov. 20 marked the first time in 100 years that an authentic Wright Flyer successfully flew. The flight flew 97 feet into a 12-mph wind out of the north.

A second flight was successfully flown for 115 feet on Dec. 3rd. This flight had to cope with crosswind and upon landing with the left wing low, broke several ribs.

Several replicas of the 1903 Flyer have also flown. Replicas, however, differ in some respect such as materials, engine, and structure from the original Wright Flyer. Even the Flyer that hangs from the ceiling of the Air and Space Museum differs in some subtle respects from its original configuration.

Some of the teams that built replicas claimed that an authentic Flyer could not fly and it was dangerous to try.

The remains of the damaged original Flyer were badly damaged at Kitty Hawk in 1903 and stayed in crates in Dayton for 13 years. They were further abused when the crates were submerged in the great Dayton flood of 1913.

In 1916 Orville reconstructed the Flyer for the first time in thirteen years for display at a dedication of two new buildings at MIT in Cambridge, Mass. Damaged parts and material were replaced at that time. The reconstruction was guided by Orville’s memory because no detailed engineering drawings were ever made. Precise accuracy was not required because the plane was being reconstructed for display and not for flight.

The Flyer underwent another reconstruction in 1925 in preparation for being sent to the Science Museum of London.

The Wright Experience (WE) conducted a detailed investigation into the construction of the original Flyer using photographs and existing artifacts. They found that there were subtle but significant changes between what they discovered and the Smithsonian drawings of the Flyer made in 1985. Those drawings were considered the most accurate at the time and were used in building many of the replicas.

The reproduction Flyer built by the WE reflects changes such as the shape of the canard and the placement of bracing wires.

The WE installed a digital onboard flight data recorder on their Flyer that allowed the acquisition of 15 channels of in-flight data during the evaluation flights. They also conducted 20-hours of simulated flight tests in the wind tunnel at Langley in Hampton, Va.

What follows next is an overall summary of what the WE learned about the behavior of the Flyer.

First of all they confirmed that the Flyer is flyable; however it takes considerable knowledge and experience to do it well. The Wrights said that stability depends on the skill of the pilot because the machine was not designed to have inherent stability. The WE team gained a tremendous respect for the competence of the Wrights as operators of their flying machines, “something that 100 years of flying has not improved upon.

Some of the WE technical findings are provided next.

The lower wing is nominally 2 feet above the ground during the takeoff roll. The resulting ground effect produces a substantial contribution to lift and a reduction in induced drag.

The wings, having an anhedral shape (10-inch droop), also provide a contribution to lift as well as facilitating level flight.

Controlled flight is possible at a few feet of altitude, so the ground effect plays a significant role throughout the flight profile.

The Flyer can only rotate 3.5 degrees on takeoff before the tail will strike the rail. At this point the target rotation speed is 26-mph.

The tail assembly is hinged so that a higher degree rotation does not necessarily result in damage to the plane.

As noted before, the Flyer is substantially unstable. The Wrights wanted it that way because they wanted to exercise control over the airplane in flight. The center-of-gravity of the machine is located 2-feet aft of the 6.5-foot leading edge of the wing. The camber of the wing is 5%. The location of the center of gravity is too far to the rear and is responsible for much of the instability that caused undulation during flight.

Because of the machine’s instability, it never flies strictly at trim. It will operate over the full range of canard travel and corresponding variations in the angle of attack.

To maintain control, the Flyer must be operated within a narrow range of warp deflections and sideslip angles. Yaw is affected by the propwash over the vertical tail.

There is large roll power available and that helps reduce the need for full deflection and thereby also reduces adverse yaw.

The flight on Dec. 3rd demonstrated the roll instability of the aircraft and its behavior in side slipping conditions. About one-second after takeoff, a left crosswind caused the airplane to roll right. The pilot, Kevin Kochersberger, compensated for the crosswind by holding a slight right warp during roll.

The right wingtip hit the sand. The airplane recovered and continued to fly, although the ground strike caused a strong left roll. The left wing then struck the sand resulting in terminating the 115-foot flight.

A crosswind complicates the takeoff because warp corrections held on the rail must be lessened immediately at rotation as the angle of attack increases.

Kevin found that a positive canard deflection of least 10 degrees is necessary to initiate flight. Once takeoff speed is reached, the Flyer requires significant positive canard to rotate.

While flying, the unstable machine requires the pilot to continually make adjustments to maintain pitch. Kevin reports that the Flyer has a soft feel to its handling in part caused by the lag between the canard movement and the pitch response.

In addition to the natural instability of the airplane, it is very flexible structurally which makes all control responses a little less crisp than what a pilot would prefer.

With the canard being repeatedly operated almost to its limits, there is a sense by the pilot that the airplane is being over controlled.

The pilots from the WE found that the arched shape of their body they had to assume for forward visibility was not comfortable for long periods of time. They also found that the placement of their elbows was awkward because of the location of the fuel mixture control and the fuel line.

A good grip on the canard actuator was needed to work the hip cradle that required 14 pounds of force (same force as the Wrights found). Otherwise, the pilot’s body moves but the cradle doesn’t.

Stanley Allyn, chief executive officer of the NCR, was with Orville Wright at Wright Field shortly before Orville’s death. They were observing a new airplane in flight test.

Allyn asked Orville how he would like to fly that one. He looked startled for a moment and then answered that he couldn’t begin to.

Orville continued, “Wilbur and I lay on our stomachs, our hips in a cradle which connected to the wing tips by cables. When we shifted our hips to left or right, the wings were warped and the plane banked accordingly. We had no instruments, and had to judge how hard to push by the pressure exerted on our bodies by the plane in flight. You might say the flier just felt his way along.”

And so it was in 2003 also.

Reference: “Flying Qualities of the Wright 1903 Flyer: From Simulation to Flight Test,” by Kevin Kochersberger, Ken Hyde and others, AIAA-2004-0105, 42nd AIAA Aerospace Sciences Meeting, Reno, NV, Jan. 5-8, 2004

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