MBB Bo 105

Summary

Category	Helicopter
Origin country	🇩🇪 Germany
First flight	16 February 1967
Year of introduction	1970
Number produced	1500 units
Average unit price	$0.6 million

Description

In 1964, Bölkow initiated development work on the helicopter that would become the Bo 105, although work on its hingeless rotor had begun earlier. On 16 February 1967, the second Bo 105A prototype made its maiden flight in Ottobrunn, Germany, followed by the first public demonstration in May 1967. The test program was divided into stages due to the entirely new airframe, rotor system, and engine; early flights used a Westland Scout rotor and Allison Model 250 turboshafts as substitutes. Sud Aviation collaborated with Bölkow, modifying an Alouette II to test the Bo 105's rotor. The third prototype featured the initial production standard MAN Turbo 6022 turboshaft engines, and six pre-production Bo 105s were built for testing.

On 13 October 1970, the German Civil Aviation Authority certified the Bo 105, leading to initial deliveries to ADAC Air Rescue and the Bavarian State Police. In 1972, certifications from the FAA and CAA enabled exports to the United States and Britain. An improved version with more powerful engines, the Bo 105C, was developed in 1972, quickly replacing the Bo 105A. The prototype Bo 106, which shared many similarities to the Bo 105 but with a widened cabin area, performed its first flight on 25 September 1973, but the project was discontinued. In 1976, the Bo 105CB, equipped with more powerful Allison 250-C20B engines, was introduced. It was further developed into the Bo 105CBS, featuring a 10-inch fuselage stretch to meet American demand for EMS operations. Boeing-Vertol partnered in production and development and marketed the type in the US.

License manufacturing agreements led to production of the Bo 105 CB and CBS variants in the Philippines, Indonesia, and Spain, in addition to the main production line in Germany. In 1984, the Bo 105LS was developed, combining the fuselage of the CBS with uprated Allison 250-C28C engines to increase the maximum take-off weight and enhance hot-and-high flight performance; the Bo 105 LS was manufactured under a cooperative arrangement with Eurocopter Canada. Eurocopter formally ended Bo 105 production in 2001, superseded by the Eurocopter EC135. By the end of production, 1,406 rotorcraft had been manufactured in Germany, and including license production in Canada, Indonesia, the Philippines, and Spain, the total reached about 1640.

The Bo 105 exhibits high maneuverability; certain variants were designed with aerobatic capability. The aircraft featured a substantial useful load capacity and a cruise speed competitive for its era. The controls are steady and responsive. Most models can perform steep dives, rolls, loops, and turnovers. The rotor system is hingeless, with a solid titanium rotor head to which the four blades are bolted. The flexibility of the rotor blades absorbs movements, eliminating the need for hinges. The blades are composed of reinforced-plastic glass-fiber composite material, simplifying maintenance and extending blade lifespan. As of 1991, the hingeless rotor system had recorded zero failures in over six million operating hours across the fleet. The rigid rotor design contributes to the type's agility and responsiveness. Military operators commonly operate the type at very low altitude, with the helicopter's flight qualities well matched to such operations.

When outfitted with optional auxiliary fuel tanks, a basic model Bo 105 had a flight endurance of roughly five hours under load. In the event of a single engine failure, the Bo 105 could typically continue its flight, albeit with a reduction in cruise speed and range. The cabin can be configured to accommodate up to three passengers on a single rear bench, which can be removed to make room for cargo or a stretcher. Cargo and stretchers can be loaded and unloaded via the large clamshell doors located at the rear of the fuselage. In a maritime context, the BO 105 can be equipped with auxiliary fuel tanks, emergency flotation equipment, an inflatable life raft, folding rotor blades, and high skid landing gear.

Military variants of the Bo 105 could be equipped with various armament configurations. The Bo 105P/PAH-1 variant was specifically designed as an anti-tank helicopter, armed with up to six Euromissile HOT Anti-Tank Guided Missiles (ATGMs). The Bo 105 could be equipped with rockets, such as 2 x 12 SNEB or 2 x 28 SNIA. The platform could also carry 8 x BGM-71 TOW missiles or 4 x Air-to-Air Stinger missiles.

In 1975, the German Army decided to acquire a specialized anti-tank version, designated as the Bo 105 PAH-1, armed with up to six Euromissile HOT missiles. Between 1979 and 1984, a total of 212 Bo 105 PAH-1s were delivered. Operational limitations, including capabilities in nighttime combat and self-protection, led to the subsequent development of the Eurocopter Tiger. In 1977, the German Ministry of Defence selected the Bo 105C for its light observation helicopter (VBH) program, resulting in the procurement of an additional 100 rotorcraft. MBB licensed the production of the Bo 105 to Indonesian Aerospace (IPTN) in the 1970s. The Bo 105 has been utilized by various branches of the Indonesian National Armed Forces, being deployed during operations in East Timor and Papua.

Similarly, the Mexican Navy operated armed Bo 105s for maritime reconnaissance, equipping Uribe-class patrol vessels with the capability to handle the helicopter for off-shore operations. In South Korea, the Republic of Korea Army aviation procured Bo 105s in the late 1990s to enhance reconnaissance and surveillance. These were co-produced with Korea Aerospace Industries (KAI) and designated as the Korean Light Helicopter (KLH).

Main Variants:

Bo 105A: The first production model, intended primarily for civil use and equipped with two Allison 250-C18 turbine engines.
Bo 105C: An early improved version developed in 1972, it was equipped with two Allison 250-C20 turbine engines.
Bo 105CB: The main production version from 1975, it was powered by two 313 kW (420 shp) Allison 250-C20B engines.
Bo 105CBS: A utility transport version featuring a fuselage stretched by 25 cm (9.8 in) and an extra window.
Bo 105P/PAH-1: An anti-tank helicopter armed with wire-guided HOT ATGMs for the West German Army, designated "PAH-1".

Technical specifications

Version: Bo105P/PAH-1
Height	3.0 m (9.9 ft)
Length	11.9 m (38.9 ft)
Service ceiling	5182 m (17001 ft)
Empty weight	1675 kg (3693 lbs)
Max. takeoff weight	2700 kg (5952 lbs)
Powerplant	2 × turbines Allison 250-C20R3 delivering 332 kW