{{Short description|German two-seat glider}} <!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. --> {{Infobox aircraft | name= G103A Twin II | image= File:Grob 103 79N.jpg | caption= | type=Two-Seater Class sailplane | national_origin=Germany | manufacturer=Grob Aircraft | designer= | first_flight= | introduction= | retired= | status= | primary_user= | number_built=549 | developed_from= | variants= }}

The '''G103 Twin II''' (originally designated the '''G 118''') is a high-performance two-seat sailplane manufactured in Germany by Grob Aircraft. The aircraft is of T-tail configuration, and is fitted with upper-surface airbrakes and a non-retractable undercarriage. Of fiberglass construction, it is designed for training, high performance cross-country racing and simple aerobatic flying.

==Design and development== thumb|Grob G103 Twin II landing. Clear view of the new three-wheel undercarriage configuration.

The G103 Twin II (a.k.a. the Twin Astir II) is the successor of the original G103 Twin Astir with a nose wheel and a fixed six-inch main gear fitted behind the center of gravity - The main wheel is equipped with a hydraulic brake. Modified ailerons produce a substantially improved roll response compared to the previous model. Approach control is by top surface Schempp-Hirth type airbrakes. The G103A Twin II Acro variant features strengthened mainspar caps and steel control pushrods which permit greater aerobatic performance. The G103 also has a FAA approved modification kit for all-hand control for handicapped operation.

The Royal Air Force Air Cadets acquired 100 Twin II Acros (known in service as the '''Grob Viking''' T1) in 1984/85 to replace the aging Slingsby gliders of the RAF Volunteer Gliding Schools.<ref name="cadet direct">{{cite web |title=RAF Air Cadets – The History Behind the ATC |url=https://www.cadetdirect.com/blog/air-cadet-history-atc/ |website=Cadet Direct |access-date=2 December 2019 |date=13 August 2019}}</ref>

A total of 549 were produced before it was succeeded in production by the G103C Twin III in 1989.

==Operational history==

===Records=== On 28 September 1981 the Twin II took the world Out & Return record for two-seat sailplanes (1000.88&nbsp;km/ 621.92 miles).<ref>[http://records.fai.org/gliding/aircraft.asp?id=3191 History of Gliding World Records: List of records established by the 'Grob Twin Astir II' ] {{webarchive|url=https://web.archive.org/web/20071013163927/http://records.fai.org/gliding/aircraft.asp?id=3191 |date=2007-10-13 }}</ref> The aircraft (N424GL) was flown out of the Ridge Soaring Gliderport, Pennsylvania, USA, by pilot Thomas Knauff and crew, Rob Gannon.

On May 14, 1996 the Twin II G103A took the Pennsylvania State Open Multi place class; Distance around a Triangular Course/Speed over a Triangular Course of 100&nbsp;km; Pilot David F. Bradley, Sr. Passenger Jim Vincent. and the Pennsylvania Sports Class; Distance around a Triangular Course of 100&nbsp;km; Pilot David Bradley, Passenger Jim Vincent.<ref>[http://www.ssa.org/members/badgesandrecords/RecordTable.asp ssa.org] {{webarchive|url=https://web.archive.org/web/20110606065647/http://www.ssa.org/members/badgesandrecords/RecordTable.asp |date=2011-06-06 }}</ref>

===In-flight limitations=== In 2003 Service Bulletin 315-64/2 reduced the maximum admissible airspeeds and prohibited aerobatic flight. This was due to reports that the design of the fuselage may not have been sufficient to sustain limit loads during certain maneuvers and during flight at certain speeds. Grob completed further investigations into the effects of certain flight conditions on the fuselage structure and the development of corrective procedures. Further static strength tests were conducted to verify the safety margin of the fuselage. The results of these tests restored the original flight speed limitations and maneuver operations for the Twin II and allowed the Twin II Acro only basic aerobatic maneuvers (spins, lazy eights, chandelles, stall turns, steep turns, and positive loops). An approved modification, when incorporated, restores full acrobatic status to these sailplanes.<ref>[http://www.grob-aerospace.net/fileadmin/service_bulletins/g103/G103_315_66_1.pdf Service Bulletin 315-66/1]</ref>

==Operators==

;{{ARG}} *Argentinian Air Force<ref>[http://www.eam.iua.edu.ar/avi_astirtwin01.asp Escuela de Aviación Militar Equipment]</ref> ;{{AUS}} *Australian Air Force Cadets ;{{BEL}} *Belgian Air Component for Royal Belgian Air Cadets ;{{ITA}} *Italian Air Force Gliding Centre<ref name="G103 Twin Astir">{{cite web |title=G103 Twin Astir |url=http://www.aeronautica.difesa.it/mezzi/mlinea/Pagine/G-103TWINASTIR.aspx |publisher=Aeronautica Militare |access-date=29 May 2020}}</ref> ;{{UK}} *Royal Air Force<ref>[https://www.raf.mod.uk/aircraft/viking-t1/] www.raf.mod.uk Retrieved: 13 December 2009</ref> Royal Air Force Gliding and Soaring Association ;{{USA}} *Civil Air Patrol

==Specifications== [[File:Glider Launch.jpg|thumb|right|Viking T1 used by the British Air Cadet Organisation launching at 662 VGS, RM Condor]] thumb|right|Royal Air Force/Air Cadets Viking T1 {{Aircraft specs |prime units? = met |crew=Two |length m=8.18 |length ft=26 |length in=10 |span m=17.50 |span ft=57 |span in=5 |height m=1.55 |height ft=5 |height in=1 |wing area sqm=17.8 |wing area sqft=191 |wing loading kg/m2= 32.6 |wing loading lb/sqft= 6.68 |aspect ratio=<!-- sailplanes -->17.1 |empty weight kg=380 |empty weight lb=837 |gross weight kg=580 |gross weight lb=1,280 |max speed kmh=250 |max speed mph=160 |cruise speed kmh=85 |cruise speed mph=62 |g limits=+5.3/-2.65 at Va<!-- aerobatic --> |glide ratio=<!-- sailplanes -->ca. 36.5 |sink rate ms=0.64 |sink rate ftmin=<!-- sailplanes -->126 }}

==See also== {{aircontent <!-- include as many lines are appropriate. additional lines/entries with carriage return. --> |see also= * Grob G103 family * Grob G103 Twin Astir * Grob G103c Twin III |related=<!-- related developments --> |similar aircraft=<!-- similar or comparable aircraft --> |lists=<!-- related lists --> * List of gliders }}

== References == {{reflist}} * [https://web.archive.org/web/20070214012256/http://www.sailplanedirectory.com/PlaneDetails.cfm?planeID=368 sailplanedirectory.com] * [https://web.archive.org/web/20120415082648/http://www.soarminden.com/images/Grob103POH.pdf Grob G 103 Twin II POH]

==External links== {{commons category|Grob G 103 Twin II}} * [https://web.archive.org/web/20010331183137/http://www.ssa.org/Magazines/Johnson.asp Johnson R, A Flight Test Evaluation of the Grob G103 Twin II, Soaring, Feb 1983] * [http://www.grob-aircraft.com/ Homepage of Grob Aircraft AG] * [https://web.archive.org/web/20060820150514/http://www.adelaidesoaring.on.net/Aircraft/ASC%20-%20Grob%20G103%20guide%20A5%2005.pdf A PDF information guide based on the Flight Manual, from Adelaide Soaring Club]

{{Grob aircraft}}

Category:Grob aircraft Category:1980s German sailplanes Category:T-tail aircraft