| PZL P.7 | |
|---|---|
 PZL P.7 | |
| General information | |
| Type | Fighter |
| Manufacturer | PZL |
| Status | retired |
| Primary user | Poland |
| Number built | 149+2 |
| History | |
| Manufactured | 1932–1933 |
| Introduction date | 1933 |
| First flight | October 1930 |
| Developed from | PZL P.6 |
ThePZL P.7 was a Polishgull wing monoplanefighter aircraft designed in the early 1930s at thePZL factory inWarsaw. It was the main fighter of thePolish Air Force between 1933 and 1935. The PZL P.7 was replaced in Polish service by its follow-up design, thePZL P.11c. More than 30 PZL P.7 fighters remained in service during theInvasion of Poland, scoring several kills despite its obsolescence.
The history of the PZL P.7 began in 1928, when a talented designer namedZygmunt Puławski designed an all-metal, metal-covered monoplane fighter, thePZL P.1. It introduced a high gull wing whose design was called the "Polish wing" or "Pulawski wing." The P.1 was powered by aninline engine and developed a speed of 302 km/h (188 mph). But it remained a prototype because a decision was made to use a licence-producedradial engine in the Polish Air Force fighters. So the next model, thePZL P.6, flown in August 1930, was powered by theBristol Jupiter VI FH radial engine. Both aircraft were well received and it won the AmericanNational Air Races in August–September 1931.
The PZL P.6 did not enter production because a more advanced variant, thePZL P.7, was in development. The first prototype was basically a P.6 with a more powerful Bristol Jupiter VII.F engine. The addition of asupercharger improved performance at higher altitudes. The prototype P.7/I was first flown in October 1930 byBolesław Orliński.[1] Initially, engine cylinders had individual cylinder fairings. After numerous changes, most noticeably the addition of a wideTownend ring to the engine, and a higher aspect tail, the second prototype P.7/II which had been completed in autumn 1931, was accepted for production with the designationP.7a. The wing was redesigned with slightly increased span, taken from thePZL P.8, and shorterailerons were used, and structural changes eliminated external ribs from the wing upper surfaces.[1] P.7a production began in mid-1932 and the last of the 149 (plus two prototypes) were completed in 1933.[1] ThePolish Air Force received the P.7a in 1933.
Puławski continued to develop the basic design by adding more powerful engines, which resulted in thePZL P.11. Puławski preferred inline engines and also designed the slimmerP.8 and the related P.9 with inline engines but he died in an air accident in March 1931, and these were cancelled. The P.11 became the standard Polish fighter while thePZL P.24 was developed in parallel as an export variant in 1932.
The all-metal,duralumin metal-covered strut braced gull-wingmonoplane was conventional in layout, and used a conventional fixed undercarriage with a tail skid. The two-spar trapezoid wing was thinner by the fuselage and was covered with a ribbed Wibault type duralumin sheet (although the upper surfaces were smooth) and braced by two struts on each side. The fuselage was framed in a front section and semi-monocoque in mid- and tail sections, oval in cross-section. In keeping with the period, the pilot's cockpit was open with a windshield. Armament was two 7.92 mm (0.312 in) machine guns mounted on the fuselage sides which replaced the initially fitted 7.7 mm (0.303 in) Vickers E which were re-bored. The aircraft was powered by a 360 to 390 kW (480 to 520 hp)Bristol Jupiter VII F radial engine fitted with aTownend ring and two-blade propeller. A main 290 L (64 imp gal; 77 US gal) fuel tank in the fuselage, behind the engine could be dropped in case of a fire emergency. The second fuel tank was 7 L (1.5 imp gal; 1.8 US gal).
The PZL P.7a entered service in spring 1933, replacing PWS-A (a licence-builtAvia BH-33) andPWS-10 fighters. Consequently, thePolish Air Force became the first air force entirely equipped with all-metal monococque fighters.[1][2] When the P.7 entered service, it was comparable to contemporary designs, but due to rapid progress, it was obsolete by 1939. From 1935, thePZL P.11 replaced the P.7 in most combat units, but was only a slight improvement, while the P.7as were relegated to air schools.
At the outbreak ofWorld War II on 1 September 1939, the Polish Air Force still had 30 PZL P.7a fighters in combat units. A further 40 were with flying schools, and 35 were in reserve or undergoing repairs for a total of 106 aircraft. The P.7as were used by three squadrons, each equipped with 10 aircraft. ThePursuit Brigade's123rd Squadron was deployed nearWarsaw, while the151st and the162nd Squadrons were attached to Army units. Despite being obsolete, they engaged the German attackers during theinvasion of Poland. In addition to combat units, at least 18 P.7a fighters were used by improvised units from air bases inDęblin and Ułęż.
Although the P.7 was more manoeuvrable than their opponents and could operate from short or rough fields, almost all the German aircraft were faster, and worse, the Polish aircraft and their engines were worn out from intensive service use. Their two machine guns was also inadequate and jammed frequently while only some replaced the vintage Vickers with the betterPWU FK wz.33 [pl].[1] Pilots flying the P.7a claimed to have shot down seven German aircraft (twoHeinkel He 111s, twoDornier Do 17s, oneHenschel Hs 126 and twoMesserschmitt Bf 110s), against 22 losses.
Most were destroyed in 1939, in combat or on the ground, but around a dozen were withdrawn toRomania, but were not used in combat there. Some captured P.7s were used by the Germans for training. Several aircraft were captured by the Soviets and were also assigned to training units.
Data from Polish Aircraft 1893–1939[3]
General characteristics
Performance
Armament
Related development
Aircraft of comparable role, configuration, and era
