Grob G103 Twin Astir

The Grob G 103 is a two-seater glider Grob Aircraft AG Mindelheim im Allgäu, which is used mainly for training and also for aerobatic training ( in the ' Acro' version). The Twin Astir is a further development of the single-seater G 102 Gliding Index is 92

The glide ratio is 38, the maximum speed ( VNE ) is 250 km / h and the maneuvering speed at 170 km / h The Acro versions are fully aerobatic; they are permitted thus for load factors of 6 / - 4g, additional reinforcements of the hull are made. The standard versions are approved for aerobatics; the maximum load factors are at 4 / -2.65 g

  • 4.1 Twin III Acro
  • 4.2 Twin III 20 m
  • 4.3 Twin III SL


The following versions have been produced:

  • Twin Astir
  • Twin Astir Trainer
  • Twin II
  • Twin II Acro
  • Twin III
  • Twin III Acro
  • Twin III 20 m
  • Twin III SL

Twin Astir

The Twin Astir was developed as a two-seat counterpart to Astir and officially announced the end of 1975. The first flight of the prototype took place in December 1976 with some delay.

It has a retractable landing gear and ballast tanks for the cross-country flight. The Twin Astir Trainer has been derived as a separate series from the standard model and differs from the latter mainly by the absence of the ballast tanks and the suspension, not retractable landing gear. Both versions are approved for aerobatic maneuvers and could be converted to a fully aerobatic capable Acro version.

In 2003, investigations of the fuselage structure pointed out that " the collateral damage to the hull below limit loads may not be sufficient ." Then, the maximum speed was reduced in all variants and revoke permission for acrobatics flights at the Acro versions. But Aerobatics could still be carried out. A year later, the top speed was indeed raised again to 250 km / h, but the art flight ban remained.

Twin II

The Twin II is the successor of the Twin Astir dar. on ballast water has been omitted here; unsprung, not retractable main landing gear was placed behind the center of gravity and supplemented by a nose wheel.

Twin II Acro

The Twin II Acro is a variant of the Twin II, which was directed by additional reinforcements of the structure on the aerobatics. She was with the techniques suitable for aerobatic training doubles for a long time a tough competitor of the ASK 21 The Royal Air Force ordered 100 copies of the Twin II Acro and requires at least some of them still under the name Viking T Mk1 at the Volunteer Gliding Squadrons as a training aircraft, a.

In addition, tests performed after a longer operating time and assuming increased "Damage - tolerance " resulted in the need for a torsionssteiferen fuselage. Subsequent modifications (installation of reinforcements in the fuselage ) are required for the restoration of extinct after these tests Acro full approval.

Twin III

The Twin III is the development of the Twin II It has a modified wing in trapezoidal shape. The hull is largely identical. The Twin III was produced in a total of 13 copies and, in contrast to the Twin III Acros a carbon fiber hull (CFRP / carbon). The Twin III is limited aerobatic capability ( category U).

Twin III Acro

The version Twin III has a different airfoil than the Twin II with a significantly lower coefficient of lift in inverted flight. The Twin III Acro is approved for aerobatics, but not suitable because of the high minimum speed in inverted flight for aerobatic beginners training. Since 2004 need for the restoration of aerobatic certification of the Twin III Acro the same changes to the hull are performed as they are necessary in the Twin II Acro. The last -built copy of the Twin III has already received the steerable nose wheel version Twin III SL, so that the ground handling is much easier.

Twin III 20 m

The Twin III 20 m is the advanced version of Twin III. The glider is identical to the Twin III, it was only the span increased by fitting of winglets on the wingtips to 20 meters. Thus, the glide ratio improved from 38 to 41 The Twin III 20 m can also be converted to twin III by the winglets to be removed and in its place shorter wing ends are attached.


The evolved version of a self-launching two-seater called the Twin III SL was built with retractable engine from the Twin III. It is equipped with a fold- Rotax 505A with 43 ​​hp and a variable pitch propeller. In contrast to the non-motorized version of the Twin III the nose wheel is steerable running, what should facilitate taxiing on the ground.