Archive for December, 2013

BK117

Monday, December 23rd, 2013

The BK117 is a twin-engine, medium size helicopter developed jointly by Messerschmitt Bolkow Blohm (MBB) of Germany and Kawasaki of Japan. In early 1977 the two companies signed an agreement to share costs and produce two prototypes each. Although development took longer than originally planned, Japanese and German authorities certified the helicopter in late 1982 followed by the United States in early 1983.

The BK117 is a compact design with a total length of 43 feet and a main rotor diameter of 36 feet. MBB used a hinge-less rotor system with four main rotor blades attached to a titanium hub. A high tail rotor and rear clamshell doors made the BK117 very popular in the EMS industry.

The first version was the BK117 A-1 powered by two Lycoming gas turbine engines. Two major problems with the A1 were the low gross weight (6280 lbs) and a lack of tail rotor thrust and stability. In 1985 MBB introduced the A3, with a larger tail rotor, an optional yaw stabilization augmentation system (YSAS) and a gross weight increase to 7,055 pounds. A year later came the A-4, with increased take-off limits and an improved tail rotor hub. All A-series BK117s use the 650 shp Lycoming LTS-101- 650B1 turbine engine de-rated to 550 shp.

In 1987 MBB introduced the B1, which used the more powerful 750 shp LTS-101- 750B1 engine (still de-rated to 550 shp) and the YSAS became standard equipment. Next was the B2, with a beefier landing gear, shorter pitch change horns to improve main rotor response time and a gross weight increase to 7,385 pounds. Also available at the same time was a C1 model with Turbomeca Arriel 1E engines rated at 708 shp for better hot and high performance.

BK117

BK117

 

 

 

 

 

 

 

 

 

In 1992, MBB and the helicopter division of Aerospatiale merged to form Eurocopter. Under the newly formed company, the BK117 underwent several upgrades including a new forward cockpit design with modern avionics. It carries the FAA designation BK117 C2, but is marketed as the EC145. Powered by a pair of Turbomeca Arriel 1E2 engines rated at 738 shp each, the gross weight jumped to 7903 lbs. In 2006, the US Army signed a contract for 345 EC145 aircraft for use as a light utility helicopter. Known as the UH 72A (Lakota), the program has been a major success for the US Army.

UH 72A Lakota

UH 72A Lakota

EC145

EC145

 

Scheduled for certification in 2014 is the EC145 T2 featuring new FADEC equipped Arriel 2E engines delivering 1039 shp each. Additional improvements include a Fenestron tail rotor, a 4-axis autopilot and a gross weight increase to 8047 lbs.

EC145 T2

EC145 T2

Volocopter

Saturday, December 7th, 2013

Over the years there have been many different inventors and engineers who have attempted to built vertical lift aircraft. The single main rotor with a smaller anti-torque rotor emerged as the most popular. With recent advances in technology, innovative engineers have been attempting to build a practical electric-powered helicopter. As it turns out, the single main rotor design is not the most efficient – efficiency is necessary for an electric-powered helicopter to be capable of lifting a reasonable payload. As such, engineers are designing very different vertical lift vehicles. One of these is the 2-person Volocopter and its first successful flight was November 17, 2013.

Designed and built in Germany, the Volocopter has an especially unique design. It uses 18 rotors, each powered by its own electric motor. They are mounted on a light weight carbon fiber ring above the cabin. Several on-board computers monitor and control the speed of each rotor system to achieve directional control – eliminating the need for any type of mechanical linkage. The system is designed so that if one of the motors fails (actually, several can fail at the same time) the aircraft can still safely land. Additionally, there is a ballistic parachute system for added safety.

Currently, the biggest limitation is battery life. The battery allows a flight time of 20 minutes, however, the company believes that advances in battery technology will extend the flight time in the near future. As an interim solution, the Volocopter will be built as a hybrid which will allow several hours of flight time. This is achieved by using a combustion engine to power a generator that supplies the batteries and motors with electricity.

The manufacturer, E-volo, claims the production aircraft will be extremely cost effective to operate, very quiet and easy to fly. More information can be found on their website: www.e-volo.com.

vc200_first-flight_13

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