Arup S-4

S-4
Role	Blended wing body aircraft Type of aircraft
National origin	United States of America
Manufacturer	Arup Manufacturing Corporation
Designer	Dr. C.L. Snyder, Raoul Hoffman
First flight	19 March 1935
Introduction	1935
Retired	bought and flown with a patched crack in its wood spar to a museum in the Dallas Ft Worth area in the early 70s
Number built	1
Developed from	Arup S-3

The Arup S-4 (Model 104) is the last in a series of round-wing aircraft from C.L. Snyder.^[1]

The S-4 was engineered by Raoul Hoffman. The test pilot was Glenn Doolittle, a cousin of Jimmy Doolittle.^[2]

The S-4 used a low aspect ratio, semi-circular planform wing with a conventional landing gear and a small rudder with attached elevator on the rear of the fuselage. The aircraft was entered through a door mounted on the bottom of the aircraft.^[3]

The S-4 prototype flew extensively in promotional demonstrations. The S-4 was emblazoned with Sears Roebuck and Company logos. The aircraft was scrapped for war materials in World War II.^[4]

• Hoffman Flying Wing a design based on the Arup S-4 aircraft.^[5]
• Milt Hatfield Little Bird - similar design.^[6]

A replica is on display in the atrium of South Bend Airport^[7]

Data from Janes, Popular Aviation

General characteristics

• Capacity: 2
• Length: 18 ft 6 in (5.64 m)
• Wingspan: 22 ft (6.7 m)
• Wing area: 273 sq ft (25.4 m²)
• Airfoil: NACA M-6
• Empty weight: 650 lb (295 kg)
• Gross weight: 1,200 lb (544 kg)
• Fuel capacity: 18
• Powerplant: 1 × LeBlond 70-5 5-cyl. air-cooled radial piston engine, 70 hp (52 kW)
• Maximum speed: 100 kn (115 mph, 185 km/h)
• Service ceiling: 9,000 ft (2,700 m)
• Rate of climb: 580 ft/min (2.9 m/s)