Grob G 109B Vigilant T1 – Technical Information
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.
Operational history (Vigilant T1)
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.Grob G 109B
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. 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.
Grob G 109B Vigilant T1 of the RAF
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 908kg 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.
Crew: Two (student and instructor)
Length: 8.10 m (26.57 ft)
Wingspan: 17.4 m (57.09 ft)
Height: 1.7m (5.58 ft)
Wing area: 19.0 m² (204.5 ft²)
Empty weight: 620 kg (1,364 lb)
Loaded weight: 850 kg (1,874 lb)
Max takeoff weight: 908 kg (2,001 lb)
Powerplant: 1× Grob 2500E1 4-cylinder air-cooled piston engine, 71 kW (95 hp)
Never exceed speed: up to 850 kg: 130 knots (below 6,500 ft), 122 knots (above 6,500 ft). (851 to 908 kg: 121 knots)
Service ceiling: FL80 (2,438 m)
Wing loading: 47.8 kg/m² (9.79 lb/ft²)
Source Document – Wikipedia