By Pam Mickelson
As you walk into the museum the R4360 could be one of the most impressive sites you'll see. The engine towers above most displays -- only matching the height of the United 727 cockpit. The R4360 at the museum is on loan from Melvin & Judy Vavra of Elk Point, SD.
The Pratt & Whitney R4360 Wasp Major (as it is known) was a large radial piston aircraft engine designed and built during World War II. It was the last of the Pratt & Whitney Wasp family and the culmination of its maker's piston engine technology, however, the war was over before it could power airplanes into combat.
The R4360 is a 28-cylinder, 56 spark plug, four-row air-cooled radial engine. Each row of pistons was slightly offset from the previous, forming a semi-helical arrangement to facilitate efficient airflow cooling inspiring the engine's "corncob" nickname. Although reliable in flight, the Wasp Major was maintenance-intensive. Improper starting technique could foul all 56 spark plugs.
The Wasp Major engine was developed near the end of World War II to power the Boeing B-50, an improved version of the successful B-29 Superfortress. The B-50 had four R4360 engines.
The R4360 is an air-cooled radial engine that produces a maximum of 3,500 hp and weighs approximately 3,500 pounds (1,575 kg). R4360s have been used to power various post-WWII USAF bombers, cargo/transports and aerial tankers, including the B-36 bomber, the B-35 Flying Wing, the C-74 Globemaster, the C-97 Stratofreighter, the Consolidated XC-99, the C-119 Flying Boxcar and the C-124 Globemaster II aircraft. The passing of the KC-97 and C-97 series aircraft from Air Force inventory in the late 1970s marked the closing of the era of both the large piston engine and the turbo-supercharger within the USAF.
October - March
Monday: 10:00 am - 4:00 pm
Thursday - Saturday: 10:00 am - 4:00 pm
CLOSED Tuesday, Wednesday, Sunday
Closed New Years, Easter, Memorial Day, July 4, Thanksgiving, and Christmas.
Click Here for Summer Hours
Directions & Contact the Museum
2600 Expedition Court
P.O. Box 3525
Sioux City, IA 51102
Click Here for Directions
Cost of Admission
Seniors (65+): $5.00
Active Military: $5.00
Children (5-14 yrs): $3.00
4 yrs & under: Free
Group Tours (8 or More): $5.00/Person
Request group tours here