Granville Gee Bee Model Z Super Sportster

The Granville Gee Bee Model Z was an American racing aircraft that was built, successfully raced to victory, then destroyed in a deadly crash – all in 1931. It was the first of the Super Sportster aircraft built by Granville Brothers Aircraft of Springfield, Massachusetts, with the sole intent of winning the Thompson Trophy, which it did in September 1931. Its fatal crash that December started the reputation of subsequent Gee Bee aircraft as killers.

Design and development
Suffering from the effects of the Great Depression, the Granville Brothers decided in July 1931 to build an aircraft to compete in that fall's Thompson Trophy competition at the National Air Races in Cleveland, Ohio. They hoped that a victory in the prestigious race would lead to additional orders for their line of sporting aircraft.

Constructed in less than five weeks at a cost of under $5,000 USD, the Gee Bee (for "Granville Brothers") Model Z, named City of Springfield, was a small, tubby airplane. It was essentially the smallest possible airframe constructed around the most powerful available engine of a suitable size, a supercharged Pratt & Whitney Wasp Junior (R-985) radial engine, producing 535 hp.

Operational history
First flying on August 22, 1931, the Gee Bee Z quickly proved to be tricky to fly, but fulfilled every expectation with regards to its speed. Flown by pilot Lowell Bayles, the Gee Bee Z attained the speed of 267.342 mph at the National Air Races during the Shell Speed Dash qualifying on September 1, then went on to win the Goodyear Trophy race, run over a course of 50 mi, the next day at an average speed of 205 mph. On September 5, the aircraft's engineer, Bob Hall, flew the Gee Bee Z to victory in the General Tire and Rubber Trophy race, then won again the next day in a free-for-all event.

In the Thompson Trophy Race on September 7, Bayles was triumphant, winning with an average speed of 236.24 mph, winning over competitors including Jimmy Doolittle, James "Jimmy" Wedell, Ben Howard, Dale Jackson, Bill Ong, Ira Eaker, and Hall, who finished fourth in a Gee Bee Model Y.

Following the Thompson Trophy race, the Gee Bee Z was re-engined with a larger, 750 hp Wasp Senior radial, in preparation for an attempt at establishing a world speed record for land planes at Wayne County Airport in Detroit, Michigan. Unofficially clocked at 314 mph on a trial run, it surpassed the previous record of 278 mph by attaining 281.75 mph on December 1, 1931, but the margin was too small for the record to be officially registered. A further record attempt on December 5, 1931, ended in tragedy, the aircraft suffering a structural failure of its right wing on its final approach. The air racer, flying level at an altitude of less than 500 ft, suddenly rotated through four rolls, out of control, and crashed amid a large fireball, killing Bayles.

It was suspected that the Model Z's crash during the December 1931 speed run was due to an unexpected failure of the gasoline tank cap, which may have come loose and passed through the windshield. A bullet-proof windscreen and internal fuel caps were part of the later Gee Bee designs. Analysis of motion picture film of the event, examined frame-by-frame, is inconclusive. Aileron flutter was thought to be the cause of the wing's failure. It was theorized that the gas cap struck the pilot and incapacitated him, causing a sudden upset in pitch that led to uncontrolled flutter in the right aileron, exerting undue high vibration stress on the right wing, causing it to fail. The air racer immediately pitched up out of control. Tests of an exact reproduction aircraft has since shown that the Gee Bee Z was susceptible to aerodynamic flutter at high speeds. The 1932 R-1 and its sister ship, the R-2, were the successors to the previous year's Thompson Trophy-winning Model Z.

Legacy
Film of the crash of the Gee Bee Z has become some of the most well known footage from the era of air racing. The crash also helped to establish the reputation of Gee Bee racing aircraft as killers. The Super Sportster design would be refined into the Gee Bee Model R for the 1932 air race season.

Two reproductions of the Gee Bee Z have since been constructed. One, a faithful reproduction of the original aircraft, was built by Jeff Eicher and Kevin Kimball of Mount Dora, Florida, and is housed in the Fantasy of Flight museum in Lakeland, Florida. The other, constructed by Bill Turner in 1978, features extended wings and fuselage for improved flight characteristics. It appeared in 1991 as both a static and flying prop in the Walt Disney feature film The Rocketeer; it is now on display at the Museum of Flight in Tukwila, Washington.

Popular culture
Kermit Weeks, founder of Fantasy of Flight, used a Gee Bee Model Z as his main character "Zee" in a series of children's books set around the interwar period.

A modified, flying replica of the Gee Bee Model Z appeared in several scenes in the 1991 Walt Disney feature film, The Rocketeer.