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.
Sikorsky Aircraft Corporation, Bridgeport, Connecticut
Specifications from Aero Digest, April, 1935:
• President: Fred W. Neilson. Vice-president in charge of engineering: Igor I. Sikorsky.
Forty-five place high-wing seaplane. A TC 454. Four P. & W. Hornet engines, 575 horsepower each.
Span 114 feet. Length overall 76 feet 8 inches. Height overall 23 feet 10 inches. Wing [...]
Seversky Aircraft Corporation, Farmingdale, New York
Specifications from Aero Digest, April, 1935:
• President: Alexander P. de Seversky. Vice-president: R. G. Ervin. Chief Engineer: A. Kartveli. Export representative: Miranda Bros., 6 E. 45th Street, New York, N. Y.
Two- or three-place open amphibion. Wright Whirlwind engine, 420 horsepower.
Span 36 feet. Length overall 26 feet 4 [...]
Security National Aircraft Corporation, Van Nuys, California
Specifications from Aero Digest, April, 1935:
• President and General Manager: W. B. Kinner. Vice-president: A. C. Essig. Sales Manager: Hugh H. Green. Chief Engineer: Max B. Harlow.
Two-place open low-wing monoplane. Security S-5 engine, 120 horsepower. ATC 521.
Span 40 feet. Length overall 23 feet 11 inches. Height [...]
A long distance aircraft of the 1920s
All-metal, high-wing monoplane
The freezing Arctic wind penetrated the unheated, corrugated metal craft taking off from Spitsbergen, Norway. Navigator Richard Byrd, an ambitious U.S. Navy Commander, and pilot Floyd Bennett struggled to keep warm in their furs. They made a long flight north that day, and on their return [...]
Two-place high-wing monoplane. LeBlond engine, 70 horsepower.
Advertisement and schematic from Aero Digest, April, 1935:
Porterfield Aircraft Corporation, Kansas City, Missouri
• President and General Manager: E. E. Porterfield, Jr. Vice-president: M. S. Porterfield. Designer and Production Manager: N. R. Hockaday. Chief Engineer: Hugh L. Thompson.
Span 32 feet. Length overall 20 feet. Height overall 6 feet 7 inches. [...]
From Aero Digest, April, 1935:
Pitcairn Autogiro Company, Willow Grove, Pennsylvania
• President: Harold F. Pitcairn. Vice- president: James G. Ray. Chief Engineer Agnew E. Larsen.
TW0-place open direct control autogiro.
Wright Whirlwind R-975E engine, 420 horsepower at 2150 revolutions per minute. Diameter of rotor 46 feet 2 inches. Length overall 21 feet 10 inches. Height overall 11 [...]
A Wilford Gyroplane looks like an Autogiro but differs in that its rotor blades are controllable from the cockpit, and rigid save for a feathering motion. The idea behind this craft was a scheme for feathering the pitch of the blades rotating round the hub instead of the blade flapping system which La Cierva [...]
From Aero Digest, April, 1935:
The Northrop Corporation, Inglewood, California
• Five- or eight-place low-wing monoplane. ATC 553. Wright Cyclone SR1820 F-3 engine, 710 horsepower at 7000 feet, or Wright Cyclone SR1820 F-2 engine, 735 horsepower at 4000 feet or P. & W. of equivalent power. Span 47 feet 9.5 inches. Length overall 33 feet 1.125 inches. [...]
From Aero Digest, April, 1935:
The Northrop Corporation, Inglewood, California
• President: John K. Northrop. Vice-president, General Manager and Sales Manager: W. K. Jay. Export representative: E. P. Howard, 51 Canton Road, Shanghai, China.
One-place open (or closed) low-wing mail monoplane. ATC 549. Wright Cyclone SR1820, F -3 engine, 710 horsepower at 7000 feet. Span 47 feet 9.5 [...]
From Aero Digest, April, 1935:
Mercury Aircraft, Incorporated, Hammondsport, N. Y.
• President and General Manager: J. F. Meade. Vice-president and Chief Engineer: H. C. Mummert.
Two-place open high-wing monoplane. ATC 235. LeBlond engine, 90 horsepower. Span 35 feet 8 inches. Length overall 23 feet. Height overall 8 feet 7 inches. Wing area 192 square feet. [...]
