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The Crosby CR-4 is a racing aircraft developed in the late 1930s

CR-4
CR-4 displayed at the EAA Airventure Museum
Role	Racing aircraft Type of aircraft
National origin	United States
Designer	Harry Crosby
First flight	April 1938
Number built	1
Developed from	Crosby CR-3

Development

The Crosby CR-4 is the follow-on of the Menasco C6S-4 powered Crosby CR-3 (a.k.a. C6R-3) designed to be powered by a twelve-cylinder Ranger V-770 engine[1] The aircraft was designed while Crosby was recovering with a broken back and fractured skull from the 1936 crash of his all metal CR-3. Despite a prior failure causing a crash, money shortages prompted Crosby to reuse the Menasco C6S-4 engine from his former racer. Funding for construction came from fellow racer Kieth Rider. Students from the Curtiss-Wright Technical Institute in Glendale, California assembled the aircraft.[2]

Design

The CR-4 is a low-wing monoplane with conventional landing gear. The construction is all-metal stressed skin. The triangular wings featured a straight leading edge with a long chord tapering to a point at the wingtips. The left cowling held a combination oil tank and surface cooler. The seat and canopy adjusted up six inched in travel for take off and landing visibility. The landing gear used compressed air from a Lux air bottle rather than mechanical or hydraulic mechanism.[3] Copper filings found later in the line, combined with wind resistance prevented one leg from locking.[4]

Operational history

The first flight was performed in April 1938 at Mines Field with severe aileron flutter and a wheel collapse on landing.

• 1938 Greve races. Crosby landed while on fire in the 14th lap from an engine manifold that fell off in flight.[5]
• 1938 Thompson Trophy races. The CR-4 was repaired just in time for the race but landed with fuel leakage problems.
• 1939 Greve races. Crosby's landing gear failed to retract from a leaking compressed air tank. Crosby landed after 14 laps with a third-place finish.
• 1939 Thompson Trophy. Crosby finished fourth with engine troubles.

In late 1939, the CR-4 was filmed for use in the movie Tail Spin. In 1945, Crosby died while bailing out of a XP-79B. The CR-4 was sold by his wife to be restored by its new owner. The aircraft was placed in storage in a school bus until purchased by Morton Lester. Lester donated the airframe to the EAA Airventure museum in Oshkosh, Wisconsin, where it was restored and placed on display.[6]

Variants

• Crosby CIP-5 - With the onset of WWII, Crosby developed an all wood interceptor around the CR-4 design and its intended Twelve cylinder Ranger engine. Construction material was wood rather than the advanced all-metal design of the prior racers.[7]

Specifications (CR-4)

Data from Sport Aviation

General characteristics

• Crew: 1
• Length: 21 ft 6 in (6.55 m)
• Wingspan: 16 ft (4.9 m)
• Empty weight: 1,540 lb (699 kg)
• Powerplant: 1 × Menasco C6S-4 Inline, 260 hp (190 kW)
• Propellers: 2-bladed, 6 ft (1.8 m) diameter

Performance

• Maximum speed: 335 kn (386 mph, 621 km/h)

References

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