Podlaska Wytwórnia Samolotów PWS-18
In April 1935, the Polish government, looking for an intermediate military trainer, bought two Avro 621 Tutor trainer aircraft. Production was ordered in the PWS (Podlaska Wytwórnia Samolotów - Podlasie Aircraft Factory). Negotiations began for licensed production in Poland but reached an impasse. Under the contract, the Polish Avro 621 were equipped with Bristol engines, and the engine production in Poland has not yet been established. When the license was obtained, there is a problem with the release of the licensed copies of the aircraft. As a result, both Avro 621 were sent to Podlaska Wytworna Samolotow (PWS) to review the design.
In 1935, Antoni Uszacki of the PWS modified the design, fitting it with a Wright Whirlwind engine, produced under licence in Poland. The new engine cowling was much longer than the previous Townend ring type, with a carburetor air intake below it. The wing construction was changed from metal to wooden, better fitted to PWS capabilities, and the rectangular wing tips were rounded. Also some other details were changed, such as a tailskid instead of a tailwheel.
A series of 40 aircraft was built in 1935-1936. They were assigned military numbers 80-1 to 80-40. Designated PWS 18, these machines differed only "cosmetic" improvements and American Wright J-5B "Cyclone" engines.
They were not produced in larger numbers because a successful indigenous Polish advanced trainer, the PWS-26, using the same engine, was designed and entered production.
PWS-18s were used in the Polish military aviation flight schools and training squadrons of the 4th Regiment in Torun, among others in Airforce Training Center in Dęblin, an NCO school for minors in Bydgoszcz and in training escadres of air regiments. None survived World War II.
Most of the aircraft survived until the outbreak of war, and for some time they have been used to provide communications between the Polish armies. Some PWS 18 were then captured by the Germans and used in flight schools Luftwaffe in Poland.
Engine: 1 × Avia Wright Whirlwind J-5B, 240 hp / 220 hp nominal (176 kW / 162 kW nominal)
Wingspan: 10.98 m (36 ft ⅛in)
Wing area: 29.40 m² (316 ft²)
Length: 8 m (26 ft 2⅞ in)
Height: 2.92 m (9 ft 6⅞ in)
Empty weight: 926 kg (2,037 lb)
Loaded weight: 1,220 kg (2,684 lb)
Wing loading: 41.5 kg/m² (8.49 lb/ft²)
Power/mass: 0.144 kW/kg (0.0894 hp/lb)
Maximum speed: 196 km/h (106 knots, 122 mph)
Cruising speed: 169 km / h
Range: 465 km (251 nm, 289 mi)
Service ceiling: 4,900 m (16,000 ft)
Rate of climb: 5 m/s (980 ft/min)
Crew: 1, instructor
Capacity: 1, student
Armament: 1 x 7.92 mm machinegun, pilot's or observer's (optional),
Bombload: 2 x 12-kg bombs (optional)