The low-powered Samolot Sp.I, designed in Poland in the mid-1920s, was intended to explore the characteristics of a proposed single seat fighter. The project did not receive government support and only one Sp.1 was built.
| Samolot Sp.I | |
|---|---|
| |
| Role | Single seat research aircraft |
| National origin | Poland |
| Manufacturer | Samolot |
| Designer | Piotr Tulacz |
| First flight | July 1926 |
| Number built | 1 |
Design and development edit
The designer of the Samolot Sp.1 was Piotr Tulacz, the technical director of Samolot. A private venture, it was intended to be a research development vehicle for a more powerful fighter aircraft and, in addition, to demonstrate to the Government that high performance aircraft could be built with Polish materials.[1]
The Samolot Sp.1 was a braced parasol wing monoplane. Its two-part wing, rectangular in plan apart from blunted tips, was moderately thick. Each half-wing was built around a pair of wooden spars and was covered with plywood, then joined centrally and supported just above the fuselage on cabane struts. Primary wing bracing was provided on each side by a parallel pair of steel struts, enclosed in wooden streamlined cladding, from the lower fuselage to the wing spars.[1]
It had been designed to accept radial engines in the 60–89 kW (80–120 hp) power range and when the Sp.I was completed in the mid-1926 the only available engine was an elderly six-cylinder Anzani 6A-4 which gave 67 kW (90 hp). This was housed under a circular cross-section metal cowling with its cylinder heads protruding for cooling. The cowling blended smoothly into the rest of the fuselage which was a 2 mm (0.08 in) thick ply-skinned semi-monocoque, tapering to the rear. The pilot's open cockpit was just behind the trailing edge of the wing, where there was a small cut-out to improve his field of view. The Sp.1's tailplane and fin were integral parts of the fuselage and also ply covered, as were the control surfaces; the elevators were divided.[1]
The Sp.I had a conventional, fixed undercarriage with a track of 1.50 m (4 ft 11 in). The mainwheels were on a single axle with rubber-cord shock absorbers, mounted on steel V struts from the fuselage at the base of the wing struts. These struts, like the wing bracing, were clad in wood streamlining.[1]
The first flight, flown by Samolot's chief test-pilot Edmond Holodynski at Poznan-Lawica, was in July 1926. Further flight-testing showed a lack of power but also some handling problems and instabilities. The latter were soon corrected by a reduction in fuselage length and some rudder modifications and the aircraft was re-engined with a 89 kW (120 hp) Salmson 9Ac, a nine-cylinder modern radial. As a result, the Sp.I handled well and bettered its calculated performance.[1]
Despite its good performance, Samolot failed to get Government funding and Sp.I development was abandoned. It did leave a legacy, in that some of the engineers who had worked on its design subsequently joined the design team of the successful PWS-10, another braced parasol wing aircraft.[1]
Specifications (Salmson engine) edit
Data from Cynk (1971)[1]
General characteristics
- Crew: One
- Length: 6.1 m (20 ft 0 in)
- Wingspan: 8.92 m (29 ft 3 in)
- Height: 2.3 m (7 ft 7 in)
- Wing area: 15 m2 (160 sq ft)
- Airfoil: Dewoitine 26A
- Empty weight: 530 kg (1,168 lb)
- Gross weight: 715 kg (1,576 lb)
- Fuel capacity: 130 L (29 imp gal; 34 US gal)
- Powerplant: 1 × Salmson 9AC 9-cylinder, air-cooled radial, 89 kW (120 hp)
- Propellers: 2-bladed
Performance
- Maximum speed: 190 km/h (120 mph, 100 kn)
- Landing speed: 60 km/h (37 mph; 32 kn)