Grob G103a Twin II

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The G103a Twin II (originally designated the G 118) is a high performance two-seater sailplane made by Grob Aerospace. The aircraft is of T-tail configuration, and is fitted with a non retractable undercarriage and upper surface airbrakes. Of glass fibre construction, it is designed for training, high performance, and simple aerobatic flying.

The G-103 Twin II (a.k.a the Twin Astir II) is the successor of the original G 103 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 Schemmpp-Hirth type airbrakes. The Acro variant of the Twin II (G103a) features strengthened mainspar caps and steel control pushrods which permit greater aerobatic performance. The Royal Air Force acquired 100 Acros (known as the Viking T1) for its Air Cadet training program. The G103 also has a FAA approved modification kit for all-hand control for handicapped operation.

A total of 549 were produced, including 100 Viking TX.1s for the UK Armed Forces before it was succeeded in production by the 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 km/ 621.92 miles). [ [http://records.fai.org/gliding/aircraft.asp?id=3191 History of Gliding World Records: List of records established by the 'Grob Twin Astir II' ] ] 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 100KM; Pilot David Bradley, Passenger Jim Vincent. and the Pennsylvania Sports Class; Distance around a Triangular Course of 100km; Pilot David Bradley, Passenger Jim Vincent. [ [http://www.ssa.org/members/badgesandrecords/RecordTable.asp ssa.org] ]

In-Flight Limitations

In 2003 Service Bulletin 315-64/2 reduced the maximum admissible airspeeds and prohibited acrobatic 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. [ [http://www.grob-aerospace.net/fileadmin/service_bulletins/g103/G103_315_66_1.pdf Service Bulletin 315-66/1] ]

pecifications

aerospecs
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crew=Two
capacity=
length m=8.18
length ft=26
length in=10
span m=17.50
span ft=57
span in=5
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width m=
width ft=
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height m=1.55
height ft=5
height in=1
wing area sqm=17.8
wing area sqft=191
swept area sqm=
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rot area sqm=
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volume m3=
volume ft3=
aspect ratio= 17.1
empty weight kg=395
empty weight lb=869
gross weight kg=580
gross weight lb=1,280
lift kg=
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max speed kmh=250
max speed mph=160
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glide ratio= ca. 36.5
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sink rate ms= ca. 0.64
sink rate ftmin= 126

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References

* [http://www.sailplanedirectory.com/PlaneDetails.cfm?planeID=368 sailplanedirectory.com]

External links

* [http://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-aerospace.net/index.php?id=399 Service Bulletins on the Grob website]
* [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]