Monday, October 6, 2008

New Wright “B” Flyer at NBAA show was an engineering challenge

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NEWS - For Immediate Release - October 6, 2008

Dayton, OH — A one-of-a-kind lookalike of the Wright brothers’ first production airplane is making its public debut today through Wednesday, October 6-8, at the National Business Aviation Association’s (NBAA’s) annual convention in Orlando, Fla.

The Wright “B” Flyer lookalike is the product of an all-volunteer team that designed and built the airplane in less than a year.

Dayton, Ohio-based Wright “B” Flyer Inc., which owns two other, separately designed lookalikes of the Wright Model B, decided in 2007 it needed a new airplane for a new mission: telling the story of Dayton’s and Ohio’s aviation heritage to the world with an airplane that can be shipped internationally for exhibition flights.

The first sortie of that mission is its non-flying display before an expected 33,000 business professionals at this event, which NBAA calls the world’s biggest civil aviation trade show. Dubbed the “Silver Bird” because of its silver-painted frame and white fabric, the airplane is in its final stages of construction. Its first flight is expected in early 2009.

Wright “B” Flyer Inc.’s Model B Flyer lookalike, dubbed the “Silver Bird,” partially completed in July 2008. Photo credit: Wright “B” Flyer, Inc.

A flying ambassador

“It will truly be a global ambassador for Dayton. There is not a single artifact you can hold, or place you can visit, or document you can read that equals seeing a Wright Flyer in the air,” said Amanda Wright Lane of Cincinnati, great grandniece of the Wright brothers and a Wright “B” Flyer Inc. trustee.

Wilbur and Orville Wright invented the airplane in their West Dayton bicycle shop at the turn of the 20th Century and formed the Wright Company in 1909 to produce military and civilian airplanes. The “B” model was the first one they produced in quantity, with more than 100 built beginning in 1910. Configured with tail-mounted rudder and elevator, it was the first Wright airplane without a front elevator, as well as the first with wheels.

Famous military and civilian air pioneers such as Air Force Gen. Henry “Hap” Arnold, magazine publisher Robert J. Collier, and aviatrix Ruth Law learned to fly in Wright “B” Flyers. The Wright Company’s exhibition team exposed thousands of Americans to flight, mainly in Model B airplanes, at air shows around the country in 1910 and 1911. A Model B made the first air cargo flight on November 7, 1910, carrying bolts of silk from Dayton to Columbus, Ohio, for a department store.

Wright “B” Flyer Inc.

Wright “B” Flyer Inc., located at Dayton-Wright Brothers Airport, is an all-volunteer, not-for-profit organization that promotes the Wright brothers’ aviation heritage. Since 1982, it has been flying its one-of-a-kind lookalike of a 1911 Army Model B Flyer at the annual Vectren Dayton Air Show and other events around the Dayton region. During summer months, it also displays a non-flying civilian Model B on Huffman Prairie in cooperation with the National Park Service and Wright-Patterson Air Force Base. Its airplanes and hangar-museum are a part of the National Aviation Heritage Area, an eight-county region around Dayton that includes 10 national aviation heritage sites.

Nicknamed the “Brown Bird,” the Army Signal Corps lookalike soared over the Rose Bowl and circled the Statue of Liberty in 2003. It was displayed at Tempelhof Airport in Berlin, Germany, in 1990.

But it is difficult and expensive to disassemble the Brown Bird and ship it to remote locations, especially overseas. At the same time, worldwide interest in the Wright brothers’ pioneering work has grown, and Wright aircraft are in demand. This year, the organization shipped its non-flying airplane to England for display at the Farnborough International Air Show.

In 2007, the organization launched a project to design and build a new Model B Flyer that could be loaded into a standard cargo shipping container, shipped anywhere in the world, and put together in one hour for exhibition flights. More than 30 skilled volunteers have been responsible for its design and construction, and several businesses have donated materials, parts, or fabrication services.

An engineering challenge

The organization wanted an airplane that would closely resemble the original Model B in air show flybys, but be sized to fit in a standard shipping container and be easy to assemble for flight by a small crew. It also had to be rugged and reliable enough for daily use and capable of flying in more than calm conditions. In other words, the Wright brothers’ original wood-and-fabric structure, marginal control system and primitive engine would not do. But neither would the Brown Bird, which is difficult to tear down and won’t fit in a shipping container.

In materials and construction, the Silver Bird is closer to Charles Lindbergh’s Spirit of St. Louis airplane, said Walter Hoy, project engineer and coincidentally a native of St. Louis, Missouri. Both airplanes have steel frames, wooden wing ribs and fabric covers, he said.

“We did get into discussions on building aluminum structures. That I vetoed, because I don’t have people here who can work aluminum structures,” said Hoy, an aeronautical engineer. “With a steel tube structure, you grind the tubes to fit, you tack weld it together, and then you have a professional welder come in and weld it up. Amateurs can see how to do this. And the woodworking, we have excellent woodworkers. So it forced what we were going to build this airplane out of into chromoly [steel] and wood, not aluminum and not composite. … We don’t have composite engineers in this group.”

The project benefitted from technology far removed from the Wright brothers’ West Dayton bicycle shop. The team used modern engineering software tools for design and structural analysis. Lasers cut the ribs from plywood sheets, and laser-machining tools were used to make or finish many of the metal parts.

Hoy said the structure is stressed for 3.8 positive Gs like conventional light airplanes. The design includes a 150 percent safety margin, but the team didn’t want to sacrifice a wing to prove it. “The safety factor was arrived at empirically. … We tested it to operational loads, not to failure,” Hoy said.

Wing design

Design began with the wings, Hoy said. The original Wright wings were thin, spanned 39 feet and were lightly loaded. Also, the original Model B used wing warping for roll control. Hoy said the Silver Bird needed higher wing loading to make it more stable in turbulent or breezy conditions, and it needed shorter wings to fit into a shipping container. Shortening the wingspan to 33 feet and shortening the chord to 54 inches from 72 inches helped meet both goals while preserving the general appearance.

At the same time, a thicker wing was used for both a higher lift coefficient and gentler stalling traits. Hoy said the Silver Bird uses a NACA USA 35-B airfoil from the 1920s. The wings should give the airplane a 41mph stall speed and a 70-mph maximum speed.

The Wrights achieved roll control by twisting or “warping” the wings. Wright “B” Flyer Inc.’s lookalikes all have ailerons. The Silver Bird has two-thirds span Frieze ailerons on upper and lower wings.

“You give up structural strength with wing warping. If you build flexibility into the wing, you have given up the rigid truss and the strength associated with it,” Hoy said. What’s more, Hoy said working a lever to warp the wings requires “brute force” and greatly increases pilot workload.

Frieze ailerons help with an adverse yaw problem on the Model B Flyer. The Model B has vertical fins — the Wrights called them “blinkers” — mounted above the skids at the front of the plane. Hoy said these blinkers can increase adverse yaw, which causes an airplane’s nose to point in the opposite direction as it turns.

“If you get adverse yaw and it starts to swing the nose in the wrong direction, the blinkers will pull it more in that direction. … You need a tremendous amount of rudder to get the nose back around. Well, you don’t have tremendous rudder” on the Model B, Hoy said.

Frieze ailerons have lips that dip below the wing when they are angled up for a turn, which adds drag to the wing and counteracts adverse yaw. (Hoy thinks the Wrights used the blinkers to augment the rudders in turns by yawing first, then rolling.)

Walter Hoy, project engineer for Wright “B” Flyer Inc.’s “Silver Bird,” and other volunteers test-fit a drive chain on the Model B lookalike on September 30, 2008. Photo credit: Wright “B” Flyer, Inc.

Drive train

Like the original, the Silver Bird has twin counter-rotating propellers and drive chains, although a modern aircraft engine will power them. The mahogany propellers also have the bent-end look that characterized Wright Flyer props. With the fan-cooled, Lycoming HIO-360 engine turning at 2,900 rpm, the props will turn at 1,200 rpm with the reduction accomplished by the chain sprockets, Hoy said.

The drive train includes a Flexidyne coupling between the crankshaft and the chains. Hoy says the coupling dampens power impulses that might otherwise be transmitted through the chains into the structure, risking a harmonic feedback that could destroy the airplane. Wright “B” Flyer Inc.’s Brown Bird also uses a Flexidyne coupling.


The Model B had three wooden control sticks: A side sick on the right or left to control the elevator, and a stick between the pilots to control wing warping. The top section of the wing warping stick was jointed for a rudder control.

The Silver Bird has conventional controls, with a center-mounted stick at each seat to control ailerons and elevator, and foot-pedal rudder controls. The pilot’s seat, on the left, has hydraulic toe brakes.


Located near Dayton and Wright-Patterson Air Force Base, a region steeped in aerospace and automotive technology and manufacturing, Wright “B” Flyer Inc. has benefitted from a pool of highly skilled volunteers, ranging from aeronautical and electrical engineers to machinists and woodworkers. On the Silver bird project, ages have ranged from an 11-year-old who taught his elders how to rib-stitch wing fabric to a 91-year-old machinist who designed special tools to ease assembly. Hoy said at least 33 people have worked on the airplane at some point, although a core of eight has been involved throughout the project.

“I think the chief engineer on anything like this is constantly negotiating, trying to get it so it’s strong enough but light enough,” Hoy said. Indeed, the age-old battle between strength and weight has proved to be his biggest managerial challenge. The original Model B had a gross weight of approximately 1,250 pounds with a pilot and passenger; the Silver Bird will be about 1,000 pounds heavier

“We had places where we had dual quarter-inch plates butted against each other. That’s a half-inch of solid steel. … I started saying, ‘Look, this is the Wright B, not the Wright B & O,’ ” Hoy said. “It’s a constant battle in building any airplane, between the structural people and the aerodynamics people who have got to lift all this stuff. It’s normal.”

Wright “B” Flyer inc. volunteers assemble the new Wright “B” Flyer lookalike airplane, dubbed the “Silver Bird,” on Tuesday, Sept. 30, prior to shipping it to Orlando, Fla., for the National Business Aviation Association’s 2008 trade show. The assembly work is being done in the organization’s hangar and museum on Dayton Wright Brothers Airport. Parts of the larger Wright “B” Flyer lookalike, dubbed the “Brown Bird,” are visible at right. Photo credit: Wright “B” Flyer, Inc.

Future plans

When finished, the Silver Bird will be capable of flying a pilot and a passenger, either at is home base or at air shows or other events around the world. Its flight will symbolize both the aviation heritage of the Wright brothers and the aerospace industry of the Dayton region and Ohio.

It will also provide a high-profile marketing opportunity for corporate sponsors interested in aligning their company or brand names with the most famous name and image in aviation.

“Make no mistake about it. We serve a global [aviation] market today. This airplane extends our reach in promoting our aviation heritage and Ohio’s aerospace business,” said John Bosch, chairman of Wright “B” Flyer Inc. “There’s no place in the world we can’t take this airplane.”


NOTE: Photos accompany this release; captions below. Contact: Jessie Duckrow (937) 751-9427

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