In addition to its use as a civilian multi-purpose helicopter, the model is still used today mainly by government users such as the police, military, civil defence, disaster relief and air rescue services. In the Bo 105, the newly developed jointless rotor head was introduced and, for the first time in civil helicopter construction, a twin-engine drive with two shaft turbines was used.

Ludwig Bölkow and Emil Weiland started with helicopter development in Bölkow Entwicklungen KG, which was founded in 1955. As aircraft construction in Germany was initially banned by the Allies after the Second World War, Bölkow had to make up for a large development gap and faced strong competition. It was necessary to find a gap in the market in which Bölkow could hold its own against the established helicopter models. What did not yet exist was a light helicopter that was safe (due to twin engines and generally redundant design of all important systems as well as a high tail rotor), yet easy to maintain, easy to fly, suitable for rescue missions and inexpensive to maintain. 60% of the capital required for development came from loans from the German government and was to be repaid if the helicopter was commercially successful. Bölkow worked with risk sharing in the development community with the suppliers. For example, the transmission specialist ZF Friedrichshafen developed the shaft transmission and provided it free of charge for the prototypes. Other suppliers did the same with their systems.

The Bo 105 was the first helicopter in the world to have a main rotor with a rigid rotor head without flapping and swivel joints as a composite construction, consisting of a solid rotor head made of a titanium alloy with internal elastomer elements for shock absorption and tapered roller blade angle bearings for smooth rotation of the rotor blades according to the position of the swashplate.

In the EC 135, this has been further developed into the bearingless rotor head that has prevailed in most models.

The cyclical inclination of the rotor plane is achieved by the setting angle of the tiltably mounted rotor blades, which bend more in the direction of flapping as the setting angle increases. This was made possible by using glass fibre reinforced plastic (GRP) for the rotor blades – the result, the Bölkow rotor, was a light but very stable rotor with good aerodynamic properties. The Bo 105 is considered to be the first helicopter type which was able to fly a loop. It is particularly well controllable, which is why it was selected as a military helicopter (especially for anti-tank operations) in Germany and Sweden.

The prototype of the Bo 105 made its first 18-minute maiden flight with the new rotor on 16 February 1967 with chief test pilot Wilfried von Engelhardt. Although experiments were initially carried out with German-made turbines (two MAN shaft turbines with 375 shaft horsepower each), the series production was based on Rolls-Royce/Allison 250-C18 shaft turbines developed by the Detroit Diesel Allison Division (DDA) of the General Motors Corporation; the main rotor gearbox, intermediate bevel gear and tail rotor gearbox, designated ZF-FS 72A, were supplied by ZF Friedrichshafen AG.

Even before the start of series production, Bölkow merged in 1969 to form the Messerschmitt-Bölkow-Blohm (MBB) group. The Bo 105 was continuously improved in many development steps. MBB merged in 1982 to form MBB-ERNO, which became part of DASA in 1989, whose helicopter division was absorbed into the Eurocopter Group in 1992 (since 2013 Airbus Helicopters). In 1994, the Bo 105 CBS-5, a further modernised version was launched on the market. In addition to the 25.4 cm (10 inch) longer cabin and the two additional small side windows already familiar from the “S” variant, the CBS-5 models feature a further efficiency-enhanced main rotor from the German Army’s Combat Enhancement Programme and a modified ZF-FS 72E main rotor gearbox.

The MBB Bo 105 served in many technical aspects as the starting point for the development of a new helicopter, which was initially designated the Bo 108. However, even before its completion, MBB and Aérospatiale merged to form Eurocopter, now the world’s largest helicopter manufacturer, which presented the successor model as the EC 135.

With the Bo 105, the German air rescue network was established from the 1970s onwards. Compared to other helicopters of that time, the Bo 105 offered a rather spacious cabin in which medical equipment and a patient could be transported lying down. A disadvantage is that the space conditions do not allow the patient’s legs to be accessed during the flight. The new CBS-5 model came just in time for ADAC-Luftrettung, the Federal Ministry of the Interior (BMI)/Federal Border Guard and the German Air Rescue Service (DRF), which provide the majority of helicopters and pilots for air rescue in Germany, to provide relief and make room for new medical equipment in the somewhat longer cabin.

Since the Bo 105 no longer meets the new performance requirements of the EU JAR-OPS 3 directive, it was no longer permitted to be used for commercial operations from 2010 onwards; this included air rescue. It was completely replaced by quieter helicopters over the next few years. The major operators of the German air rescue network had completed the flooding by the end of 2009. By the end of 2008, the Federal Ministry of the Interior (BMI) had already decommissioned and partially sold all Bo 105s; the DRF Air Rescue had completed the phasing out by the end of 2009. The Bo 105s of ADAC-Luftrettung had already been replaced at the end of 2007. The EC 135 as well as the MBB/Kawasaki BK 117 were mainly used for the succession.

Due to its good controllability and the characteristics of the jointless rotor head, the Bo 105 CB received the certification for aerobatics in 2005. This makes the Bo 105 the only helicopter with such a certification to date. Two aircraft in Europe and two in the USA are operated by Flying Bulls for this purpose.

The Bo 105 M was developed from the civil Bo 105CB, but the transmission was increased in power and the tail rotor was replaced by a more powerful one. The Bo 105-M replaced the Alouette II as a liaison and observation helicopter (VBH) for the Army Air Corps. When the Bo 105-M was taken out of service, a shortfall in VBH’s requirements arose, so selected PAHs were retrofitted, their weapon systems removed and a rear seat was refitted. In a second step, Eurocopter and the Army Air Force will convert them to the new type P1M, so that after the withdrawal of the 40 remaining Bo 105 M in 2004, 100 Bo 105 P1M will remain in use as VBH according to current plans. The airframes of the Bo 105 P1A and 1A1 had a lower flight hour load, so that it was decided to carry out this cost-effective disarmament.

The liaison and observation helicopter was used by the German Army until the reunification of Germany by the Staff Squadrons of the Army Air Command, the Army Air Corps of the Divisions, the Army Aviation School and an Army Aviation Regiment. After the reunification of Germany, the VBHs were redistributed due to the restructuring of the Bundeswehr. The user associations are the medium transport helicopter regiments, the Army Air Corps Reconnaissance Squadron 400 and the Army Air Force School, where they serve as training and instruction helicopters for prospective pilots. The aircraft bore the tactical numbers 80+01 to 81+00

BO 105 (carpenter BO)

Karl “Charly” Zimmermann (* April 4, 1939 in Mannheim) is a German officer and helicopter pilot, most recently in the rank of Captain in the German Army’s Army Air Corps. He became internationally known as an outstanding helicopter aerobatic pilot, winning many international competitions with “his” Bo 105.

“Charly” Zimmermann shaped his flying career in the German Army, where he started at the age of 22 in April 1961. In the sixties and seventies he flew various types of helicopter, on which he completed many thousands of flying hours. However, he achieved worldwide fame on only one model: “his” BO 105, which he flew at many international air shows and competitions and at demonstration events in front of a professional audience willing to buy, mostly representatives of foreign armies. Several advertising and promotional films of the BO 105 were shot with him as pilot.

“Charly” Zimmermann is known to a broad public from many public air shows and appearances in television shows

Captain Zimmermann, together with Captain Wolfgang Kollmann, developed and perfected a multitude of aerobatic manoeuvres on the BO 105, especially the loop and the roll. Hereby “Charly” won a number of international aerobatic competitions in the seventies and eighties, such as

1977 winner of the “Silver Sword” at the “International Air Tattoo” in Greenham/Common/England as the best non-UK participant.
1978 World Champion Freestyle Flying and winner of the “Rosemary Rose Memorial Trophy” at the 3rd World Helicopter Championships in Vitebsk (USSR).
1981 World Champion and winner of the “Rosemary Rose Memorial Trophy” at the 4th World Helicopter Championships in Piotrków Trybunalski (Poland).
1983 “Silver Sword” and “Sir Douglas Bader Trophy” for the best flight demonstration during the “International Air Tattoo” in Greenham/Common/England.
1985 “Silver Sword” for the best flying display during the “International Air Tattoo” in Fairford/England.
1986 Vice World Champion in freestyle flying at the 5th Helicopter World Championships in Castle Ashby Gardens in Northampton/Great Britain behind Hermann Fuchs.

An article in ‘DIE WELT’ on June 5, 1985 documents the extraordinary aerobatic skills of “Charly” Zimmermann: NATO Supreme Commander General Bernard Rogers was guest of honour at a reception for more than 1300 officers and civilians, which the German officer corps at the allied supreme command Shape in Belgium now gave on the occasion of the German constitution day on May 23, 1985. …. Before the evening reception, helicopter aerobatic world champion Captain Charly Zimmermann of the Heeresfliegerregiment 16 (Celle) demonstrated his BO105 in breathtaking nosedives, rolls and loops in front of thousands of spectators. American helicopter pilots among the spectators then remarked: “That must have been a hallucination, no one can fly a helicopter like that”.

From 1980, “Charly” Zimmermann worked as a flight safety officer with the Heeresfliegerregiment 16 in Celle. In 1993 Zimmermann was the first German to be awarded the FAI Gold Rotorcraft Medal by the FAI. Charly” Zimmermann was also awarded the Bundeswehr Cross of Honour in Gold and the Bundesverdienstkreuz am Bande for his services to the German aviation industry.

In 1992, Captain Zimmermann successfully passed the civil aerobatics examination with the Bo 105 at the ILA 92 in Hanover in front of Dr. Vietz from the Lower Saxony Ministry of Economics and Transport, with an entry in the supplement “E” to PPL No. 2847-NIOL.

After the terrible air show accident involving aircraft of an Italian aerobatic squadron in Ramstein in August 1988, the then Minister of Defence, Rupert Scholz, decided to no longer allow the German Armed Forces to participate in air shows, which inevitably meant that the aerobatic activities of “Charly” Zimmermann had to come to an end.

“Charly” now lives with his family (as of October 2018) in retirement in the Celle area.

Bo 105 P

Anti-tank helicopter Bo 105 PAH 1

The Anti-Tank Helicopter 1 (PAH 1) has a reinforced airframe, but its avionics and dynamic system are similar to those of the Bo 105-M. A Singer-AN/ASN-129 Doppler radar was added. Its main armament consists of the Franco-German HOT wire-guided anti-tank guided missile (LFK), three of which can be carried on each side in horizontally arranged launch tubes. All the electronic equipment for missile control and detection is mounted on an equipment rack in the rear main cabin area. The gyro-stabilised APX M397 from SFIM is used as the sighting device, which is mounted directly on the cabin roof above the helicopter commander. The commander looks through a relay lens system via several diversions through this optic (3.2x and 10.8x magnification) and aims with the reticle at the object to be fought. As the optics are coupled with an infrared locator, the steering system can evaluate and continuously correct the actual deviations of the LFK HOT from the target sighting line after take-off.

As early as 1982, the plans for a combat upgrade of PAH 1 also began, for which the contract was finally awarded in 1986. AN/APR-39 radar warning systems were installed in 1983. The type designated as PAH 1A1 was converted into a troop in 1991. Externally, the PAH 1A1 can be recognised by its stepped HOT launch pads. KWS was responsible for the digitalisation of the steering computer, the control unit and the actuators for the launch ramps. This increased the ease of operation for the commander and facilitated error analysis for the maintenance personnel. A modified inlet guard (MELS) was installed in front of the air intake, the front engine cowlings were modified, the oil cooling system of the engines was revised and rotor blades with about 10 % more power were installed. These can be recognised by the rounded blade tips. Due to the widened blades, the vibration dampers at the blade root also had to be enlarged to 65 mm.

The PAH 1A1 was replaced by the Eurocopter Tiger support helicopter, formerly known as PAH 2, by 2013. During the Griffin Strike exercise at the end of August 2013 at the Artillery School in Idar-Oberstein, Bo 105s of the German Army fired a sharp shot with the HOT guided missile for the last time before the type was finally withdrawn from service.