Arup S-4

S-4
General information
Type	Blended wing body aircraft
National origin	United States of America
Manufacturer	Arup Manufacturing Corporation
Designer	Dr. C.L. Snyder, Raoul Hoffman
Number built	1
History
Introduction date	1935
First flight	19 March 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
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]

Design and development

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] [4]}

Operational history

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. ^[5]

Variants

• Hoffman Flying Wing a design based on the Arup S-4 aircraft. ^[6]
• Milt Hatfield Little Bird - similar design. ^[7]

Aircraft on display

A replica is on display in the atrium of South Bend Airport ^[8]

Specifications (S-4)

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)

References

1. Avrocar: Canada's flying saucer : the story of Avro Canada's secret projects.
2. "Round aircraft designs". Archived from the original on 2 April 2012. Retrieved 7 September 2011.
3. "Announcing the New Arup". Popular Aviation. XVII (2). Chicago, IL: Aeronautical Publications Inc: 92. August 1935. Retrieved May 31, 2025.
4. Hoffmann, Raoul (September 1935). "A Low Aspect-Ratio Plane". Popular Aviation. XVII (3). Chicago, IL: Aeronautical Publications Inc: 158. Retrieved May 31, 2025.
5. "Low AR-planes" . Retrieved 7 September 2011.
6. Experimenter. December 1957.{{cite journal}}: Missing or empty |title= (help)
7. Bernard L Rice (March 1987). "Milt's Little Bird". Sport Aviation: 43.
8. "KSBN airport". Archived from the original on 22 March 2012. Retrieved 7 September 2011.