The radial engine is an internal combustion engine in which the cylinders are arranged around a central crankshaft like the spokes on a wheel. Airplanes with radial engines have a distinctive, large, round nose.
Radial engines were very common in aircraft engines between 1920 and 1950. The cylinders are connected to the crankshaft with a master-and-articulating-rod assembly. One cylinder has a master rod with a direct attachment to the crankshaft. The remaining cylinders pin their connecting rods attachments to rings around the edge of the master rod. Four-stroke radials almost always have an odd number of cylinders, so that a consistent every-other-piston firing order can be maintained, providing smooth running. Typically radial engines had 7 or 9 cylinders. The most powerful radials had a double row, thus having 14 or 18 cylinders.
Radial engines are not rotary engines, an earlier design, in which the cylinders rotated around the crankshaft.
Some of the most famous radial engines were the Pratt & Whitney Wasp and Curtiss-Wright Whirlwind.
Waco Aircraft Company, Troy, Ohio
Specifications from Aero Digest, April, 1935:
• President and General Manager: C. H. Brukner. Vice-president: Lee N. Brutus. Sales Manager: Hugh R. Perry. Chief Engineer: A. F. Arcier.
Two-place open-or-closed biplane. P. & W. Wasp Junior engine, 420 horsepower. ATC 543.
Span 32 feet 8.62 inches. Length overall 25 feet .5 inch. [...]
Viking Flying Boat Company, New Haven, Connecticut
Specifications from Aero Digest, April, 1935:
• President: Robert E. Gross. Vice-president, Treasurer and Sales Manager: Courtlandt S. Gross. General Manager and Assistant Treasurer: Jacob L. Freed. Chief Engineer: Franklin T. Kurt.
Three-place open biplane. A TC 392. Kinner B-5 engine, 125 horsepower.
Span 28 feet 4 inches. Length overall [...]
Burnelli Aircraft, Ltd., Keyport, New Jersey
Specifications from Aero Digest, April, 1935:
• President: 1. M. Uppercu. Vice-president and General Manager: Vincent J. Burnelli. Sales Manager: H. R. Boyce. Chief Engineers: (Military division) Dr. Michael Watter; (Transport division) R. Contini.
Sixteen-place monoplane. Two P. & W. Hornet engines, 675 horsepower each.
Span 71 feet 2.4 inches. [...]
Stinson Aircraft Corporation, Wayne, Michigan
Specifications from Aero Digest, April, 1935:
• Two-place open high-wing monoplane. Lycoming R-680-4 engine, 225 horsepower.
Span 39 feet 11.5 inches. Length overall 21 feet 8 inches. Height overall 8 feet. Wing area 215 square feet. Power loading 11.75 pounds per horsepower. Wing loading 12.3 pounds per square foot.
Empty weight [...]
Stinson Aircraft Corporation, Wayne, Michigan
Specifications from Aero Digest, April, 1935:
• President: B. D. DeWeese. Vice-president: W. A. Mara. Sales Manager: J. C. Kelley, Jr.
Ten-place low-wing monoplane. Three Lycoming R-680-5 engines, 260 horsepower each.
Span 60 feet. Length overall 36 feet 10 inches. Height overall 12 feet 9 inches. Wing area 500 square feet. Power [...]
Stearman Aircraft Company, Wichita, Kansas
Specifications from Aero Digest, April, 1935:
• President and General Manager: J. E. Schaeffer. Vice-president and Chief Engineer: Mac Short. Secretary-Treasurer: Clif Barron.
Two-place open biplane. ATC 504. P. & W. Wasp Junior engine, 420 horsepower.
Span 35 feet. Length overall 25 feet 1 inch. Height overall 9 feet 4 [...]
Star Aircraft Company, Bartlesville, Oklahoma
Specifications from Aero Digest, April, 1935:
• President: John H. Kane. Vice-president, General Manager and Sales Manager: Billy Parker. Chief Engineer: Charles Peters.
Two-place high-wing monoplane. A TC 321. Lambert R-266 engine, 90 horsepower.
Span 31 feet. Length overall 20 feet 1 inch. Height overall 6 feet 8 inches. Wing area [...]
Spartan Aircraft Company, Tulsa, Oklahoma
Specifications from Aero Digest, April, 1935:
• Vice-president and General Manager: E. W. Hudlow. Chief Engineer: James B. Ford.
Four-place high-wing monoplane. Pratt and Whitney Wasp Junior engine, 320 horsepower. ATC 389.
Span 50 feet. Length overall 32 feet 7.75 inches. Height overaIl 8 feet 11 inches. Wing area 299 square feet. [...]
Sikorsky Aircraft Corporation, Bridgeport, Conn.
Specifications from Aero Digest, April, 1935:
• Seventeen-place high-wing amphibion. Two P. & W. Hornet S1E-G engines, 750 horsepower each.
Span 84 feet. Length overall 50 feet 5 inches. Height overall 17 feet 9 inches. Wing area 775 square feet. Chord 11 feet 6 inches. Power loading 11.7 pounds per horsepower. Wing loading [...]
Sikorsky Aircraft Corporation, Bridgeport, Connecticut
Specifications from Aero Digest, April, 1935:
• Thirty-seven place high-wing seaplane. ATC 544. Four P. & W. S5D-1G Hornet engines, 700 horsepower each.
Span 114 feet 2 inches. Length overall 67 feet 8 inches. Height overall 17 feet 4 inches. Wing area 1330 square feet. Power loading 13.57 pounds per horsepower. [...]
