Bolkow Bo 105 – The Teutonic Twister

Bo 105 of the Red Bull fleet seen at Pardubice, Czech Republic in 2019.

A Pioneer of Pedigree 

By the late 1960s, the helicopter had proven itself as a credible technology worthy of developing. The Korean War of the early 1950s and the Vietnam War that was raging at the time had proven beyond a doubt the helicopter’s value to military operations. In the same period of time, the civil sector was also warming up to the benefits of rotary flight.

The Bolkow Bo 105, which flew for the first time in 1967, was a major revolution in helicopter development that has had far reaching influence on helicopter design through the years. It is fitting that such a revolutionary machine should come from the company founded by the decorated and visionary Ludwig Bolkow.

Ludwig Bolkow (1912-2003) was born into aviation. His father was a forman in the Fokker aircraft company. Ludwig himself began his career in aviation working for the Heinkel aircraft company before studying aero-engineering in Berlin. Upon his graduation in 1939, he was hired by Messerschmitt and was heavily involved in development of the Bf-109 fighter and the Me-262 jet fighter.

Spanish police and army Bo 105s preserved at Madrid-Cuatro Vientos, Spain in 2018.

He created his own company in 1948 and built it into one of the largest and most respected aviation companies in post WWII Germany. He is celebrated not only as a key architect in the reconstruction of the German aircraft industry, but also as a father figure to today’s Airbus Group; Bolkow’s company was one of the cornerstones that the Airbus Group was built upon.

Bolkow was not only visionary from an aviation point of view; he was a proponent of alternative fuels and spent much of his later life researching hydrogen and solar based energy sources. Additionally, he was also revolutionary as an employer through active mentoring of his employees, company pension schemes and flexible working hours. All of those things were quite radical ideas at the time he offered them to his workers.

Bo 105 of the German army at Ostrava, Czech Republic in 2015.

Advancing the Blade 

MBB, the company created by a merger of Bolkow with Messerschmitt in 1968 and a further merger with the aircraft division of Blohm + Voss in 1969, is credited with creating the Bo 105. However, the aircraft’s design was cemented and the first flight taken prior to the merger. The Bo 105 was concieved and born in the Bolkow stables.

The Bo 105 was the world’s first light helicopter to be powered by two turbine engines. This not only gave the aircraft impressive power and performance for the class, but also increased reliability and safety.

More significantly, through the Bo 105, Bolkow introduced the rigid rotor system to the aviation world. The rigid, or hingeless, rotor system was designed around a solid titanium main rotor head that was connected to rotor blades made of composite materials that were lighter, stronger and more flexible than metal ones of the day. The rigid rotor design did away with the hinges that connected the rotor blades to the rotor head in traditional fully articulated rotor systems and used the increased flexibility of the composite rotor blades to do the job the hinges normally would do.

Savings in weight, materials and maintenance were all benefits of the rigid rotor system. The greatest benefit of the new rotor system, however, was in giving the helicopter an unprecedented level of agility and maneuverability. It was through the higher flexibility and torsional strength of the composite rotors that the Bo 105 was given it’s legendary acrobatic abilities. The Bo 105 became famous for loops, rolls and other aerobatics that previously had not been in the abilities of helicopters.

As the Bo 105 was a fully new design, great care was taken in developing it. The fuselage, main rotor and twin engine arrangement were all tested separately before being brought together.

The first prototype, designed to test the fuselage, was fitted with American engines and a main rotor of a Westland Wasp helicopter from Great Britain. Meanwhile, the rigid rotor system was first tested on a French built Sud Aviation Alouette II.

A total of six prototype aircraft were built and the Bo 105 was put into production in 1970.

German army Bo 105 seen at Ostrava in 2014.

Building a Legend 

The Bo 105 saw three decades of production before the last one was built in 2001. Nearly 1500 of the type were built on assembly lines in Canada, Germany, Indonesia, the Philippines and Spain.

The Bo 105 was originally intended primarily for the civil sector. However, through it’s agility and high rate of climb, it did attract the attention of military buyers soon after it debuted. Covering a range of 25 different variants, the Bo 105 has found much popularity with civilian and military users alike in it’s life.

Perhaps the most recognisable role for the Bo 105 to the casual observer is that of air ambulance, a vocation it excelled at for many years worldwide until was succeded by newer designs.

In civilian circles, it also has found much use in police work, film and television as well as corporate transport to name a few.

In military use, the type has been employed successfully in both inland and off-shore applications that have included training, anti-tank work, infantry support, maritime reconnaissance and border patrol.

The biggest user of the Bo 105 was the German army, who retired the type in 2016. At the height of the Cold War, the former West Germany used a variant of the aircraft called the PAH-1 as an anti-tank platform. The machine’s speed and agility, particularly below treetop level, in addition to it’s small size made the Bo 105 well suited to that role.

The Eurocopter EC-135 is one of the Bo 105’s direct descendants. This one was seen at Ostrava in 2013.

Progeny of a Pioneer 

As one would expect of a successful design, the Bo 105 was developed and became the parent of a family of light utility helicopters that inherited the rigid rotor system and admirable handling qualities of their progenitor.

However, due to a number of mergers and rebrandings in the European aerospace industry over the years it is not always easy to identify by name which helicopters have the Bo 105 in their ancestry.

MBB existed as an independent company until it was purchased in 1989 by another Germany company, DASA. By 2000, after several name changes and reorganisations, DASA was merged with Aérospatiale-Matra of France and CASA of Spain to create EADS, European Aeronautics Defense and Space. EADS eventually restructured as the Eurocopter Group and became Airbus Helicopters in 2014.

While the Airbus Group currently claims the legacy of the Bo 105 and descendant designs, the family ties can be sorted with a bit of work. Here’s a general overview of the Bo 105’s progeny:

MBB/Kawasaki BK 117 / EurocopterEC 145 / UH-72 Lakota / Airbus H 145

The first major development of the Bo 105 was the BK 117, a joint project between MBB and Kawasaki of Japan. The two companies had been working independently on light utility helicopter designs before making a deal to create a single design together.

MBB took responsibility for the rotor, tail, flight controls and hydraulics while Kawasaki tended to the landing gear, fuselage and transmission among other things. The Prototype first flew in 1979 and production began in 1982. BK 117 production ceased in 2004.

During the time the BK 117 was in production, the European share of the project came under the jurisdiction of Eurocopter in 1992. This change did not affect partnership with Kawasaki. In 1999, after a number of  of upgrades to the BK 117 were made, the Eurocopter EC 145 was introduced. The EC 145 was the basis of the UH-72 Lakota, the winner of the US Army’s light utility helicopter contract in 2006 to replace outdated Bell UH-1 and OH-58 helicopters. Another military variant was known as the EC 645.

After rebranding as Airbus Helicopters in 2014, the EC 145  and  EC 645 were redesignated as the H 145 and H 145M respectively.

MBB Bo 108 / Eurocopter EC 135 / Airbus H 135 

EC 135s in ambulance configuration seen at Ostrava in 2013

MBB started working on a refined version of the Bo 105 called the Bo 108 during the 1970s, much of that work focussed on streamlining at aircraft’s fuselage and improving controls. Development of the Bo 108 was a protracted matter that saw Aérospatiale of France becoming involved. The first of two prototype Bo 108 aircraft flew for the first time in 1988.

Initially the Bo 108 was only intended as a technology demonstrator, but developments of the aircraft through the 1990s were encouraging enough that production certification was pursued. By that point, Eurocopter had been formed and the Bo 108 was redesignated as the EC 135. A military version was developed and designated the EC 635.

In 2014 Airbus renamed the EC 135 and EC 635 the H 135 and H 135M respectively.

This TV camera equiped Bo 105 was seen at Zeltweg, Austria in 2013.

The Bo 105 Today and Learning More 

The Bo 105 is far from retired and remains a very active flyer. As of 2014, approximately 700 of the type were known to still be flying in both military and civil forms.

With technical support networks for it still firmly in place and a demand for it’s qualities still present, the Bo 105 isn’t likely to be leaving the skies any time soon and your chances of seeing one are good depending on your location.

The following links will provide you with a good deal more information on the Bo 105, it’s history, development and those behind it’s success:

This link will take you to the page of Red Bull’s Bo 105 and its pilots:
Link at The Flying Bulls

This article on Airbus Helicopters’ website will show you where the Bo 105 fits in their history:
Link at Airbus

This article gives a good description of the difference between rigid and fully articulated rotor systems:
Article at Flight Mechanic

This Article from the Ludwig Bolkow Systemtechnik website will tell you more about Ludwig Bolkow.