# PWS-15

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The **PWS-15** was a Polish single-seat [fighter aircraft](/source/Fighter_aircraft) designed as a [biplane](/source/Biplane) in the 1930s by engineers Aleksander Grzędzielski and [August Bobek-Zdaniewski](/source/August_Bobek-Zdaniewski). Constructed at the [Podlaska Wytwórnia Samolotów](/source/Podlaska_Wytw%C3%B3rnia_Samolot%C3%B3w) in [Biała Podlaska](/source/Bia%C5%82a_Podlaska), it was test-flown in December 1930. The PWS-15 served as a comparative study to the concurrently developed monoplane [PWS-10](/source/PWS-10). Despite superior flight characteristics, the PWS-15 was not selected for serial production. Instead, the PWS-10 was chosen, and the factory management ordered the disassembly of the PWS-15 prototype and suppression of information regarding its existence and performance.

## History

In 1928, engineers Aleksander Grzędzielski and August Bobek-Zdaniewski at the [Podlaska Wytwórnia Samolotów](/source/Podlaska_Wytw%C3%B3rnia_Samolot%C3%B3w) designed the high-wing fighter [PWS-10](/source/PWS-10).[1] The prototype, a competitor to [Zygmunt Puławski](/source/Zygmunt_Pu%C5%82awski)'s [PZL P.1](/source/PZL_P.1), was test-flown in March 1930. After successful trials at the [Institute of Aviation Technology](/source/Institute_of_Aviation_Technology) in mid-1930, the Polish military ordered 50 units, with an additional 30 ordered in 1931, for serial production.[2] During preparations for PWS-10 production, the designers initiated a comparative project, creating a biplane variant designated PWS-15.[3][4] In 1930, they developed documentation for a pair of biplane wings, which were fitted to one of the two PWS-10 prototypes.[5][6] The aircraft was test-flown in December 1930 by factory pilot Franciszek Rutkowski.[4][7] The test pilot reported that the PWS-15 outperformed the PWS-10 in [rate of climb](/source/Rate_of_climb), maneuverability, and handling, though it had a slightly lower maximum speed.[3][4]

Due to the advanced stage of PWS-10 production preparations and potential organizational complications, the factory management ordered the PWS-15's disassembly in February 1931 and concealed all details of its development.[3][8] The aircraft's existence was only confirmed in 1971 by one of its designers, August Bobek-Zdaniewski, over 40 years later.[9]

## Design and technical specifications

The PWS-15 was a single-engine, single-seat [biplane](/source/Biplane) fighter with a mixed construction.[10] The [fuselage](/source/Fuselage) consisted of a [truss](/source/Truss) framework of welded steel tubes, reinforced with wire bracing, featuring an oval cross-section. It was covered with [duralumin](/source/Duralumin) sheeting at the front and canvas elsewhere.[10][11] The open [cockpit](/source/Cockpit) was equipped with a windshield and a seat designed for a back-mounted parachute.[11] The instrument panel included a compass, [airspeed indicator](/source/Airspeed_indicator), [altimeter](/source/Altimeter), [turn and slip indicator](/source/Turn_and_slip_indicator), [tachometer](/source/Tachometer), water and engine oil temperature gauges, and a fuel level indicator. The engine throttle was mounted on the left side of the cockpit, while controls for emergency fuel tank jettison and radiator shutter adjustment were on the right.[11]

The wings were rectangular with rounded tips, featuring a two-spar wooden structure. The leading edges were covered with [plywood](/source/Plywood), and the rest with canvas.[10] The single-bay wing structure was connected by inverted "N" struts and reinforced with profiled steel wire bracing.[10][12] The wings had a thin (10%) [airfoil](/source/Airfoil) profile, uniform except at the tips.[10][13] The [wingspan](/source/Wingspan) was 10 metres, with a wing area of 23 m², distributed 56% to the upper wing and 44% to the lower.[5][10] [Ailerons](/source/Aileron), with a total area of 2.4 m² (59% upper, 41% lower), were fitted on both wings.[10] The [wing loading](/source/Wing_loading) was 65.8 kg/m².[14]

The aircraft was 7.5 metres long and 3 metres high.[5][10] Its empty weight was 1,145 kg, useful load 370 kg, and gross weight 1,515 kg. The [flight control surfaces](/source/Flight_control_surfaces) were conventional, with steel tube framework covered in canvas. The vertical [stabilizer](/source/Stabilizer_(aeronautics)) was adjustable, and the horizontal stabilizers were supported by single [struts](/source/Strut) and wire bracing.[10] The [landing gear](/source/Landing_gear) was a conventional two-leg design with a split axle and [Vickers](/source/Vickers) hydraulic shock absorbers, complemented by a rear steel [leaf spring](/source/Leaf_spring) tailskid.[10]

The aircraft was powered by a liquid-cooled, 12-cylinder [V engine](/source/V_engine) in a [W engine](/source/W_engine) configuration, the Lorraine-Dietrich 12 Eb, delivering 336 kW (450 hp) at 1,850 [RPM](/source/Revolutions_per_minute), with a takeoff power of 478 hp and a weight of 400 kg. It drove a fixed, two-blade wooden propeller by Szomański, with a diameter of 2.89 metres.[10][15] The power loading was 3.36 kg/hp.[14] The jettisonable [fuel tank](/source/Fuel_tank) held 280 litres, and the oil tank 30 litres.[5][10] The maximum speed was 237 km/h, [cruise speed](/source/Cruise_(aeronautics)) 210 km/h, and stall speed 88 km/h.[10][11] Fuel consumption was 100 litres per hour.[5] The aircraft achieved a [service ceiling](/source/Ceiling_(aeronautics)) of 6,000 metres with a [rate of climb](/source/Rate_of_climb) of 12 m/s at ground level.[10][11] The takeoff distance was 80 metres, and the landing distance 70 metres. The range was 410 km. The minimum turning radius was 65 metres.[10]

The armament consisted of two 7.92 mm [Vickers machine guns](/source/Vickers_machine_gun) with 500 rounds per gun, [synchronized](/source/Synchronization_gear) using a Colbert synchronizer and aimed with a Chretién [reflector sight](/source/Reflector_sight).[5][10] The aircraft was also equipped with a K-28 [gun cameras](/source/Gun_camera) and a Perkun [flare gun](/source/Flare_gun) with 10 rounds.[10]

### Livery

The PWS-15 prototype was painted olive green.[5]

## References

1. Morgała (2003, p. 36)

1. Morgała (2003, p. 37)

1. Morgała (2003, p. 38)

1. Glass (2004, p. 287)

1. Chwałczyk, Tadeusz & Glass, Andrzej (1990). *Samoloty PWS* [Aircraft of PWS] (in Polish). Warsaw: Wydawnictwa Komunikacji i Łączności. p. 158. ISBN 83-206-0899-6.

1. Cynk, Jerzy B. (1971). *Polish Aircraft 1893–1939*. London: Putman & Company Limited. p. 405. ISBN 0-370-00085-4.

1. Morgała (1972, p. 102)

1. Glass (2004, pp. 287–289)

1. Morgała (2003, pp. 38, 41)

1. Morgała (2003, p. 41)

1. Glass (2004, p. 289)

1. Morgała (1972, pp. 102–103)

1. Morgała (1972, p. 103)

1. Morgała (1972, p. 104)

1. Glass (2004, pp. 289–290)

## Bibliography

- Glass, Andrzej (2004). [*Polskie konstrukcje lotnicze do 1939 r*](https://books.google.com/books?id=VvcfAQAAIAAJ&q=Polskie+konstrukcje+lotnicze+do+1939+r) [Polish Aircraft Designs Until 1939] (in Polish). Vol. 1. Sandomierz: Stratus. ISBN 83-916327-8-4.
- Morgała, Andrzej (1972). [*Polskie samoloty wojskowe 1918–1939*](https://books.google.com/books?id=cwRNAAAAIAAJ) [Polish Military Aircraft 1918–1939] (in Polish). Warsaw: Wydawnictwo Ministerstwa Obrony Narodowej.
- Morgała, Andrzej (2003). [*Samoloty wojskowe w Polsce 1924–1939*](https://books.google.com/books?id=bUTzoQEACAAJ) [Military Aircraft in Poland 1924–1939] (in Polish). Warsaw: Bellona. ISBN 83-11-09319-9.

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Adapted from the Wikipedia article [PWS-15](https://en.wikipedia.org/wiki/PWS-15) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/PWS-15?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.