| G 109 / Vigilant T1 | |
|---|---|
| A British-registered G109B. | |
| Role | Motor glider |
| Manufacturer | Grob Aircraft |
| Designer | Burkhart Grob |
| First flight | 14 March 1980 |
| Primary user | Royal Air Force |
| Number built | 476 |
The Grob G 109 is a light aircraft developed by Grob Aircraft AG of Mindelheim Mattsies in Germany. It first flew in 1980. It is a two-seat self-launching motor glider in which the pilot and passenger or student sit side by side, with good visibility provided by large windows. As well as normal civilian use this aircraft is now used in Volunteer Gliding Squadrons by the Royal Air Force to train Air Cadets through the Gliding Induction and Gliding Scholarship courses. The Grob 109B is known in RAF service as the Vigilant T1. [1]
The G 109 was the first motor glider built using composite construction to be granted Federal Aviation Administration approval.[2]
Contents |
The aircraft is a low-wing cantilever motor glider, with a T-tail, folding (and detachable) wings, and side-by-side seating with dual controls. It is mainly constructed from glass-reinforced plastic and has a taildragger undercarriage arrangement. Entry and exit from the cockpit is via two perspex doors which open upwards individually – a modification from the original one-piece G 109 canopy. The cockpit can be heated, providing that the engine is running, and the seat backs can be adjusted and cushions of differing thickness inserted to accommodate a range of body sizes.
Total weight is around 1,870 pounds (850 kg) with a load of 506 pounds (230 kg). Cruising speed is in the region of 60–100 knots (110–190 km/h) on the 95 horsepower (71 kW) engine which can give the aircraft a top speed of 130 knots (240 km/h). The engine (based on a Volkswagen car unit) can be shut down in flight with its propeller blades feathered. The aircraft then becomes a pure glider, with a best glide ratio of around 1:28.
Under the current CAA LASORS document, the G 109 can be classed as either a touring motor glider (TMG), or a self-launching motor glider (SLMG).
The G 109B is powered by a Grob 2500 E1 horizontally opposed, four-cylinder, air-cooled petrol engine that develops approximately 95 bhp (71 kW) at 2,950 rpm. The propellor is a two-bladed, manually operated variable-pitch type driven directly from the engine. Three pitch settings can be used: Fine for take-off and general flying, Coarse for cruising, and Feathered for gliding with the engine off.
Hot air can be supplied to the twin carburettors when there is a risk of icing. An electric fuel pump is used.
The G 109 uses conventional controls, duplicated for both seats, including the throttle (not available on the left in standard production G 109s). The rudder pedals, which also operate the wheel brakes, are adjustable forward and backward to suit individuals of differing leg length and airbrakes are used to increase the rate of descent during the landing approach as well as limiting airspeed to Vne (Velocity never exceed), if required.
The Vigilant T1 variant was introduced into service in 1991, replacing the Slingsby Venture, and is used by Volunteer Gliding Squadrons (VGS) around the UK to train Air Training Corps and Combined Cadet Force cadets in basic flying with the aim of bringing them to a standard where they are able to fly solo. The Vigilant is also used by the Royal Air Force Central Gliding School, at RAF Syerston in Nottinghamshire, which trains VGS instructors as well as providing standards checking, syllabus development and engineering support.
The first two prototype aircraft (constructor's serial numbers 6001 and 6010) were designated G 109. They differed from later production aircraft by having a shorter wing span of 15 metres (49 ft). The first prototype, (registered D-KBGF), flew for the first time on 14 March 1980.[3]
The G 109A was fitted with a 2,000 cc 80 horsepower (60 kW) Limbach-Flugmotoren flat four engine (maximum power delivered at 3,400 rpm), and the wing span was increased to 16.6 metres (54 ft).
The spare engine power available was marginal in hot atmospheric conditions or when flying through rain, so around 30 G 109A airframes were fitted with a 2,400 cc 90 horsepower (67 kW) Limbach engine and an electrically controlled variable-pitch propeller. At least two aircraft have been approved to use the Rotax 912 engine. See G 109Ar.
A total of 151 G 109A motor gliders were produced.
The G 109Ar was a modification by the Aero Club Valkenburg of two aircraft with a Rotax[4] boxer-type engine for increased performance during touring and reliability. The nose of the plane is longer than that of the regular G 109A, and the engine covers are shaped differently to house the engine and its air inlets and improve airflow across the larger radiator.
Developed out of the Grob G 109A; the wingspan was further increased to 17.4 metres (57 ft), the one-piece canopy of the earlier versions was replaced with opening doors, and the main landing gear was moved rearwards to ease weight on the tail wheel.[5] The engine was replaced with a Grob-built 2,500 cc unit of 95 horsepower (71 kW).
Some aircraft in Germany have been fitted with a turbocharged engine, and with structural strengthening of the fuselage have been adapted to aero-tow gliders.
The Vigilant T1 is the designation of the adapted Grob 109B used by the Royal Air Force (RAF) for use on Volunteer Gliding Squadrons. Modifications to the Vigilant T1 include a landing light, a higher maximum all up mass (AUM) of 908 kg and a throttle for use in the left hand seat. The initial order for 53 has been topped up by aircraft bought in the private market.
General characteristics
Performance
|
|||||
|
||||||||||||||