The ASW 20 is an FAI15 metre Classglider designed by Gerhard Waibel and built by Alexander Schleicher GmbH & Co. Its fuselage is nearly identical to that of the ASW 19, mated to newly designed flapped wings for the 15 metre Class. The prototype first flew in 1977. It proved to be a highly successful glider, winning several World Championships, and was still being flown at this level up to 1995. Developments along its production life included winglets, pneumatic turbulators, and wingtip extensions. It remained in production until 1990, when it was superseded by the ASW 27. 765 were built by Schleicher and a further 140 were made under license by Centrair in France.
The ASW 20 was successful in competition, winning numerous world and national championships. Dick Johnson reported that the ASW 20 was the first 15 m glider to demonstrate a measured L/D in excess of 40:1. Roy McMaster, Karl Striedieck and John Seymour won jointly, with others, the world triangle distance record of 1,435 km (892 mi) in 1994 in an ASW 20B. ASW 20s won second and third places in the 15 metre Class at the 1983 World Championships at Hobbs, New Mexico.
The ASW 20 is constructed from glass-reinforced plastic. It features trailing edge flaps which interconnect with the ailerons and allow the entire trailing edge to operate as a flap between -9 and +5 degrees. The flaps also act as ailerons, but deflect only half of the aileron amount. Schempp-Hirth type airbrakes are provided on the upper wing surface.
The B model (introduced in 1983) differs from the A and C model in that it uses a reinforced wing spar, which provides an increased water ballast capacity at the expense of the flexible wing. The B and C model include several enhancements over the original A model, including a lifting panel, hydraulic disc brake, and automatic elevator hookup. The B and C wings also incorporate a pneumatic turbulator system, which draws high pressure air from pitot inlets on the wing and injects it through approximately 860 pinholes into the boundary layer to control underwing airflow separation.
ASW 20s that include a L designation may be fitted with a 1.59 m wingtip extension. The F designation was assigned to A variants produced in France by Centrair. Centrair also produced an FL variant equivalent to the German ASW20L; most of these are only permitted to fly without the wingtip extensions due to a deficiency in the wing spar construction.
At least three different winglet designs have been produced for the ASW 20, including a NASA winglet fitted to the Centrair gliders (FP), a design by Peter Masak, and a second generation winglet designed by Prof. Mark D. Maughmer of Penn State University (USA).
Flight characteristicsedit
ASW 20 landing
The ASW-20 is known as a very pleasant handling glider in most respects. The wing structure composite layup was designed to twist slightly as the wings flexed upward, resulting in the ability to "store" some of the energy from atmospheric gusts, and then release that energy with a very slight forward thrust force as the wings flexed back downward to their normal position. This concept is known as the Katzmayr Effect, and somewhat mimics a bird's ability to use a flapping motion to propel itself forward in flight. This unique wing twisting movement gave the ASW-20 an ability to make very small but consistent performance gains (or reduced losses) in turbulent and gusty thermal conditions compared to other competition level sailplanes.
The landing flaps (55° in early models, 38° in later models), in conjunction with very effective airbrakes, allow the pilot to make exceptionally steep approaches at slow speeds, permitting very short landings when required. Second generation winglets further improved the handling and reduced drag at low to mid speeds. Thermal performance is comparable to gliders of more modern eras.[1] These characteristics have made the ASW-20 a much beloved and desirable aircraft, even after it was no longer competitive in racing. One very common modification was the insertion of an intermediate flap setting detent (between zero and +1 position) which mitigated or softened any "tip-stall" and associated risk of spinning while thermaling in tight, gusty thermals. The flexible wing of the A and C models is particularly favored for ridge running, where it absorbs some of the tremendous turbulence found at ridgetop.
Variantsedit
Centrair-built ASW 20 FP in 1980
ASW20
Prototype and initial production
ASW20L
the ASW20 with detachable outer wing extensions to 16.59 m (54.4 ft) span, to compete in the Open-class.
ASW20B
ASW20BL
the ASW20B with detachable outer wing extensions to 16.59 m (54.4 ft) span, to compete in the Open-class.
ASW20C
ASW20CL
the ASW20C with detachable outer wing extensions to 16.59 m (54.4 ft) span, to compete in the Open-class.
^. www.sailplanedirectory.com. Archived from the original on 27 July 2013. Retrieved 12 January 2022.
^John W.R. Taylor, ed. (1988). Jane's All the World's Aircraft 1988-89. London: Jane's Information Group. p. 632. ISBN0-7106-0867-5.
Further readingedit
Milgram, Fred Thomas; Judah; translator; contributor (1999). Fundamentals of sailplane design (3rd ed.). College Park, Maryland: College Park Press. ISBN978-0966955309. {{cite book}}: |last2= has generic name (help)CS1 maint: multiple names: authors list (link)
Simons, Martin (2005). Sailplanes 1965-2000 (2nd revised ed.). Königswinter: EQIP Werbung und Verlag G.m.b.H. ISBN978-3-9808838-1-8.
External linksedit
Wikimedia Commons has media related to Schleicher ASW 20.
Alexander Schleicher GmbH & Co
Johnson R, A Flight Test Evaluation of the ASW 20, Soaring, May 1978
ASW 20 B Flight Manual
History and developmen of the ASW20, Dan Rihn, 9/4/2010
May 02, 2024
schleicher, metre, class, glider, designed, gerhard, waibel, built, alexander, schleicher, gmbh, fuselage, nearly, identical, that, mated, newly, designed, flapped, wings, metre, class, prototype, first, flew, 1977, proved, highly, successful, glider, winning,. The ASW 20 is an FAI 15 metre Class glider designed by Gerhard Waibel and built by Alexander Schleicher GmbH amp Co Its fuselage is nearly identical to that of the ASW 19 mated to newly designed flapped wings for the 15 metre Class The prototype first flew in 1977 It proved to be a highly successful glider winning several World Championships and was still being flown at this level up to 1995 Developments along its production life included winglets pneumatic turbulators and wingtip extensions It remained in production until 1990 when it was superseded by the ASW 27 765 were built by Schleicher and a further 140 were made under license by Centrair in France ASW 20 Role 15 metre or Sports Class sailplane National origin Germany Manufacturer SchleicherCentrair under licence Designer Gerhard Waibel First flight 1977 Introduction 1977 Number built 905 The ASW 20 was successful in competition winning numerous world and national championships Dick Johnson reported that the ASW 20 was the first 15 m glider to demonstrate a measured L D in excess of 40 1 Roy McMaster Karl Striedieck and John Seymour won jointly with others the world triangle distance record of 1 435 km 892 mi in 1994 in an ASW 20B ASW 20s won second and third places in the 15 metre Class at the 1983 World Championships at Hobbs New Mexico Contents 1 Construction 2 Flight characteristics 3 Variants 4 Specifications ASW 20B 5 See also 6 References 7 Further reading 8 External linksConstruction editThe ASW 20 is constructed from glass reinforced plastic It features trailing edge flaps which interconnect with the ailerons and allow the entire trailing edge to operate as a flap between 9 and 5 degrees The flaps also act as ailerons but deflect only half of the aileron amount Schempp Hirth type airbrakes are provided on the upper wing surface The B model introduced in 1983 differs from the A and C model in that it uses a reinforced wing spar which provides an increased water ballast capacity at the expense of the flexible wing The B and C model include several enhancements over the original A model including a lifting panel hydraulic disc brake and automatic elevator hookup The B and C wings also incorporate a pneumatic turbulator system which draws high pressure air from pitot inlets on the wing and injects it through approximately 860 pinholes into the boundary layer to control underwing airflow separation ASW 20s that include a L designation may be fitted with a 1 59 m wingtip extension The F designation was assigned to A variants produced in France by Centrair Centrair also produced an FL variant equivalent to the German ASW20L most of these are only permitted to fly without the wingtip extensions due to a deficiency in the wing spar construction At least three different winglet designs have been produced for the ASW 20 including a NASA winglet fitted to the Centrair gliders FP a design by Peter Masak and a second generation winglet designed by Prof Mark D Maughmer of Penn State University USA Flight characteristics edit nbsp ASW 20 landing The ASW 20 is known as a very pleasant handling glider in most respects The wing structure composite layup was designed to twist slightly as the wings flexed upward resulting in the ability to store some of the energy from atmospheric gusts and then release that energy with a very slight forward thrust force as the wings flexed back downward to their normal position This concept is known as the Katzmayr Effect and somewhat mimics a bird s ability to use a flapping motion to propel itself forward in flight This unique wing twisting movement gave the ASW 20 an ability to make very small but consistent performance gains or reduced losses in turbulent and gusty thermal conditions compared to other competition level sailplanes The landing flaps 55 in early models 38 in later models in conjunction with very effective airbrakes allow the pilot to make exceptionally steep approaches at slow speeds permitting very short landings when required Second generation winglets further improved the handling and reduced drag at low to mid speeds Thermal performance is comparable to gliders of more modern eras 1 These characteristics have made the ASW 20 a much beloved and desirable aircraft even after it was no longer competitive in racing One very common modification was the insertion of an intermediate flap setting detent between zero and 1 position which mitigated or softened any tip stall and associated risk of spinning while thermaling in tight gusty thermals The flexible wing of the A and C models is particularly favored for ridge running where it absorbs some of the tremendous turbulence found at ridgetop Variants edit nbsp Centrair built ASW 20 FP in 1980 ASW20 Prototype and initial production ASW20L the ASW20 with detachable outer wing extensions to 16 59 m 54 4 ft span to compete in the Open class ASW20B ASW20BL the ASW20B with detachable outer wing extensions to 16 59 m 54 4 ft span to compete in the Open class ASW20C ASW20CL the ASW20C with detachable outer wing extensions to 16 59 m 54 4 ft span to compete in the Open class ASW20CLT Open class glider with PSR T01 turbojet sustainer ASW20F ASW20A produced in France by Centrair ASW20FP The ASW20F with NASA winglets designed to improve performance in weak conditions 2 Specifications ASW 20B editData from Jane s All the World s Aircraft 1988 89 3 General characteristicsCrew 1 Length 6 82 m 22 ft 5 in Wingspan 15 m 49 ft 3 in Height 1 45 m 4 ft 9 in Wing area 10 5 m2 113 sq ft Aspect ratio 21 4 Airfoil root Wortmann FX 63 131 K tip Wortmann FX 60 126 Empty weight 260 kg 573 lb Max takeoff weight 525 kg 1 157 lb Water ballast 150 L 40 US gal 33 imp gal Performance Stall speed 65 km h 40 mph 35 kn without ballast Never exceed speed 280 km h 170 mph 150 kn in smooth air g limits 5 3 2 65 Maximum glide ratio 42 5 at 100 km h 54 kn 62 mph without ballast 43 at 120 km h 65 kn 75 mph with ballast Rate of sink 0 59 m s 116 ft min at 84 km h 45 kn 52 mph without ballast Wing loading 50 kg m2 10 lb sq ft See also editRelated lists List of glidersReferences edit 1 ASW20 flying notes Alexander Schleicher www sailplanedirectory com Archived from the original on 27 July 2013 Retrieved 12 January 2022 John W R Taylor ed 1988 Jane s All the World s Aircraft 1988 89 London Jane s Information Group p 632 ISBN 0 7106 0867 5 Further reading editMilgram Fred Thomas Judah translator contributor 1999 Fundamentals of sailplane design 3rd ed College Park Maryland College Park Press ISBN 978 0966955309 a href Template Cite book html title Template Cite book cite book a last2 has generic name help CS1 maint multiple names authors list link Simons Martin 2005 Sailplanes 1965 2000 2nd revised ed Konigswinter EQIP Werbung und Verlag G m b H ISBN 978 3 9808838 1 8 External links edit nbsp Wikimedia Commons has media related to Schleicher ASW 20 Alexander Schleicher GmbH amp Co Johnson R A Flight Test Evaluation of the ASW 20 Soaring May 1978 Sailplane Directory ASW20 ASW 20 B Flight Manual History and developmen of the ASW20 Dan Rihn 9 4 2010 Retrieved from https en wikipedia org w index php title Schleicher ASW 20 amp oldid 1143578762, wikipedia, wiki, book, books, library,
