Politechnika Warszawska PW-5

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PW-5 Smyk
A PW-5 at Covilhã, Portugal.
Type designation PW-5
Competition class World Class
Number built ca. 200
Crew 1
Length 6.22 m (20.4 ft)
Height 1.86 m (6.1 ft)
Cockpit width 0.63 m (2.1 ft)
Cockpit height 0.91 m (3 ft)
Wingspan 13.44 m (44.1 ft)
Wing area 10.16 m² (109.4 sq ft)
Aspect ratio 17.8
Wing profile NN 18-17
Empty mass 190 kg (419 lb)
Maximum mass 300 kg (661 lb)
Wing loading 33 kg/m² (5.6 lb/sq ft)
Maximum speed 220 km/h (119 knots)
Speed in rough air 147 km/h (79 knots)
Stall speed 60 km/h (32 knots)
Minimum sink rate 0.65 m/s at 74 km/h
(130 ft/min at 40 knots)
Best glide ratio 32 at 80 km/h (44 knots)
Roll rate 5 s at 85 km/h (46 knots)
-45° to +45° bank
A PW-5 crosses the finish line at the 2001 World Air Games in Lillo, Spain.
A PW-5 crosses the finish line at the 2001 World Air Games in Lillo, Spain.

The Politechniki Warszawskiej (pl. Warsaw University of Technology) PW-5 "Smyk" ("little rascal") is a single seater sailplane of Polish manufacture. It is the monotype World Class glider.

Contents

[edit] History

The PW-5 was designed for, and won a competition held by the International Gliding Commission for a simple, low cost sailplane that would form the basis for a new competition class, the "World Class". Unlike other soaring competition classes, the World Class designation would guarantee that all pilots participated on an equal footing, and that pilots could not gain advantage by spending large amounts of money. PW-5 was unanimously chosen from 42 design proposals in IGC international World Class design competition. In November 1989, the IGC issued a worldwide call for proposals. By February 1990, it had received 84 requests for design specifications from 25 countries. By August 1990, the IGC had received 42 design proposals from 20 countries. In September 1990, after reviewing the proposals, many of which came with models, the IGC recommended that 11 designs from 9 countries proceed to the prototype competition. In October 1992, the IGC inspected and tested 6 prototypes from 5 countries at Oerlinghausen Germany. After further review and collecting manufacturing data, in spring 1993 the IGC declared the PW-5, designed by a faculty/student team at Warsaw University of Technology, the first World Class glider.

The glider was designed at the Faculty of Power and Aeronautical Engineering of Warsaw University of Technology under supervision of Ph.D. Roman Świtkiewicz. It was originally built by PZL at its factory in Swidnik and first flew in 1993. The original members of the design team also set up a new factory at Bielsko.

It did not sell as well as expected. In total fewer than 200 PW-5's have been built, though over 70 have been exported to the United States, where there is a keen following.

[edit] General characteristics

[edit] Design and construction

  • The wingspan is 13.4 metres.
  • The structure is all glass-epoxy composite.
  • The wings are of trapeze contour with bow-shaped ends, shoulder-set on the fuselage, having a monospar structure with sandwich shells.
  • Schempp-Hirth-type air brakes extend on the upper wing surface only.
  • Fuselage shell of glass-epoxy composite monocoque structure, stiffened with frames.
  • Fabric covered rudder.
  • Fixed undercarriage consisting of main wheel behind the pilot, with shock absorber and drum brake, a smaller front wheel and a tail skid with a diminutive wheel to prevent scraping on the ground if overrotation takes place.
  • Two tow releases, for aerotowing and winch-launching respectively.

[edit] Flying, safety and operational qualities

  • Most people agree the PW-5 is very easy and fun to fly.
  • Low speed handling is nice but not fool-proof. Spin entry may not be immediately obvious to low time pilots in high stress situations.
  • While the glider can climb well in thermals, its sink-rate at inter-thermal cruising speeds is poor compared to Standard Class gliders.
  • The ailerons have a lively feeling but the roll rate is only average to fair. The rudder is relatively stiff. The control surfaces are not mass balanced and may give disagreeable positive feedback in gusts.
  • Crashworthy cockpit provides good protection.
  • Good cockpit ergonomics, except the poor visibility to the rear.
  • Undercarriage arrangement, fuselage shape, high-set wings and cruciform tail reduce the risk of damage in outlandings.
  • Very easy ground handling, assembly and disassembly.

[edit] Versions

There are only two versions of the PW-5. The Bielsko version, identified as B1 PW-5, has a few safety and performance related improvements:

  • Automatic hook-up of all controls upon assembly
  • Tow release for winch launching moved forward; this follows a winching accident in New Zealand
  • Ballast holder in the tail to allow centre of gravity corrections
  • Total Energy probe on the vertical empennage

There is a project in progress for building a motoglider designated PW-5M based on the PW-5.

The PW-5 has a two-seater derivative, the PW-6.

[edit] Designation sequence

PW-ULS - PW-2 Gapa - PW-3 Bakcyl - PW-4 Pelikan - PW-5 Smyk - PW-5M - PW-6

[edit] Sources