Brown 1926 parasol monoplane

Like several of Lawrence Brown's early designs, this parasol wing, Curtiss OX-5-engined version of the wartime Thomas-Morse S-4 biplane received no type name of its own. Both engine and airframe were available cheaply in the early post-war years.[1]

Its wing had a similar area to those of the S-4 and was rectangular in plan. Its structure was largely spruce, with two box-beam spars and an airfoil of Brown's own design. The pilot's cockpit was under the trailing edge, which had a deep, curved cut-out to assist upward vision. The wing was attached to the fuselage by pairs of near-parallel steel struts, encased in wooden fairings overlain with fabric, between the spars and the lower longerons on each side.[1]

Its fuselage was an internally wire braced, ash and spruce structure with a rectangular cross-section. The OX-5 engine, on a mounting intended to accommodate a variety of types, had its cylinders exposed and a ventilated metal cowling. Behind it, the passengers' cockpit was below the wing and between the spars. Behind the pilot's cockpit there was a curved upper decking that tapered to a tail which differed from that of the S-4, with a blunted triangular fin and rounded rectangular rudder. Its ground-adjustable tailplane was also rounded rectangular in plan, as were the elevators.[1]

The monoplane had conventional, fixed landing gear. Its wheels were on a single axle, mounted on steel tube legs with rubber shock absorbers and trailing drag struts, both enclosed in wooden streamlining. Its tailskid was made from ash.[1]

Although a modern source dates the Brown parasol to 1927,[2] a contemporary account from March 1927 notes that two had been in service for three years,[1] putting the first flight earlier than the spring of 1924.

One of these two was used in 1925 for cotton-dusting in El Salvador.[2] The total number of biplane scout to parasol transport conversions is not known.

Data from Aero Digest, 1927 (Maker's data)[1]

General characteristics

• Crew: one
• Capacity: two passengers
• Length: 23 ft (7.0 m)
• Wingspan: 40 ft 8 in (12.40 m)
• Height: 8 ft (2.4 m)
• Wing area: 260 sq ft (24 m²)
• Airfoil: Brown no.5
• Empty weight: 1,200 lb (544 kg)
• Fuel capacity: 30 US gal (25 imp gal; 110 L)
• Powerplant: 1 × Curtiss OX-5 V-8 water cooled piston engine, 90 hp (67 kW)
• Propellers: 2-bladed fixed-pich propeller

Performance

• Maximum speed: 110 mph (180 km/h, 96 kn)
• Cruise speed: 100 mph (160 km/h, 87 kn) at 75% throttle
• Range: 400 mi (640 km, 350 nmi)
• Service ceiling: 16,000 ft (4,900 m)
• Time to altitude: 10 mins to 5,000 ft (1,500 m)
• Landing speed: 38 mph (61 km/h; 33 kn)
• Payload: 300 lb (140 kg)