Grob G 109

Grob G 109
Grob G 109B
Type:	Touring motor sailer
Design country:	Germany
Manufacturer:	Gross Aircraft
First flight:	March 14, 1980
Number of pieces:	476

Touring motor glider Grob G109A with the more powerful 2400 cm³ engine

The Grob G 109 is a two-seater touring motor glider with controllable pitch propeller made by Grob Aircraft AG from Mindelheim in Swabia .

The aircraft, which is no longer in production, consists of modern composite materials (GRP), which ensure a high surface quality. Development began in 1979 and first resulted in the type certification of the Grob G109A in 1981. The prototype manager is LTB Korff, based at Mainbullau airfield .

Coarse G 109A

In the absence of inexpensive and powerful engines, a 2000 cm³ Limbach aircraft engine was installed in this model , which developed an output of 80 HP at a speed of 3400 rpm. Due to the variable pitch propeller used , the maximum speed was limited to 3200 rpm, which also cost performance. Like its successor, the Grob G 109B, the G 109A was equipped with a 160 cm Hoffmann controllable pitch propeller as standard, which has three positions: start, travel and sail.

The wingspan is 16.6 m. The maximum permissible speed (V _NE ) is 240 km / h, the cruising speed is 170 km / h, about 15 liters of super are consumed per hour. The tank holds 80 liters.

Due to the low engine power in relation to the weight, the climbing performance was moderate, especially in rain and high temperatures. Therefore the successor model G 109B was equipped with an engine developed by Grob with an output of 87 hp.

Nevertheless, the G 109A was popular with its pilots because, as the most modern aircraft in its class at the time, it combined high travel comfort with relatively good gliding characteristics and good maneuverability.

About 30 G 109A were later equipped with the 87 hp 2400 cm³ Limbach aircraft engine and a modern, electrically controlled constant-speed variable pitch propeller MTV-1-A / L from Mühlbauer. The combination of a new motor and propeller gave the sample the blue environmental angel for particularly low noise emissions, which fell from 65.9 dB (A) to 61.3 dB (A). This version was developed in cooperation between the Luftsportclub Babenhausen and the aeronautical engineering company Korff / Dietzenbach (now Mainbullau ) and brought to the Federal Aviation Office for type approval . At least two conversions to Rotax 912 and at least one conversion to a Sauer ST 2500 H1S aircraft engine with 68 kW (92 PS) are also documented.

The first two machines of the Grob G 109 (serial numbers 6001 and 6010) were delivered with a span of only 15 m. The first (prototype serial number 6001) is now flying in Bicester / England as G-CHTW. The second (6010) is registered with the registration D-KAMB in Germany and is currently based at Kamp-Lintfort Airfield (EDLC). A total of 151 G 109A were manufactured.

Grob G 109B

The aircraft, which appeared in 1983 and is no longer manufactured, was equipped with the 'Grob 2500 E1' engine, specially developed by Grob for this model, with an output of 87 hp at a speed of 3000 rpm. The span is 17.4 m. The maximum permissible speed (V _NE ) is 240 km / h, the cruising speed is 170 km / h, about 15 liters of super are consumed per hour. The minimum consumption with the standard coarse engine is 12 l / h, the tank volume is 100 l (72 kg).

Compared to the predecessor model G 109A, the B-Version differs visually mainly through the upward-swinging wing doors, the small side windows in the footwell in front of the wings and their slightly increased wing span . Further features are the toe brakes on the rudder pedals, which can be used to brake each wheel of the main landing gear regardless of the position of the rudder . This has significantly improved floor handling. The climbing performance could also be improved by the more powerful engine, which in the A version with the 2000 cm³ Limbach engine left a lot to be desired, especially in the rain.

Like the A version, the G 109B was equipped with a 160 cm Hoffmann controllable pitch propeller as standard, which has three positions: start, travel and sail.

Grob equipped the G 109B with a standard folding mechanism for the wings, so that they could be folded onto the fuselage before being placed in the hangar in order to always save limited space in the hangar . This construction also received automatic aileron connections , so that setting up and dismantling can be carried out quickly and safely.

Overall, the B version can be seen as a successful further development, even if it does not have the original maneuverability of the A version.

Starting in 2001, the type supervisor equipped around 30 G 109Bs with a 130 HP turbo engine from Limbach and an electrically driven controllable pitch propeller, which significantly improved flight performance in powered flight. With a reinforced fuselage, this version is used for inexpensive towing of gliders . The consumption is then around 25 l / h, which is about half of what conventional tow planes with Lycoming or Continental engines consume. A total of 325 G 109B were produced.

Technical specifications

Parameter	G 109A	G 109B
crew	1	1
Passengers	1	1
length	7.88 m	8.10 m
Wingspan	16.60 m	17.40 m
Wing area	20.4 m²	19.0 m²
Elongation	13.5	15.9
Surface profile	E 572	E 580
Glide ratio	30 at 115 km / h	28 at 115 km / h
Slightest sinking	1.16 m / s at 95 km / h	1.10 m / s at 108 km / h
Max. Takeoff mass	825 kg	850 kg
Wing loading	40.4 kg / m²	44.7 kg / m²
Minimum speed	76 km / h	70 km / h
Top speed	240 km / h	240 km / h

See also

• List of aircraft types

Web links

Commons : Grob G 109  - Collection of images, videos and audio files

• Homepage of Grob Aircraft AG
• Device data sheet for Grob G 109 (source LBA)
• Device data sheet for Grob G 109 B (source LBA)
• Technical data of G109A with different engines
• Experience report with G 109B turbo as a tow plane