An introduction to turbo shaft engine and helicopter aerodynamics using Eurocopter EC155-B as an example.

1. Turboshaft Engine
By: Ali Jraisheh
Department of Mechanical Engineering.
Indian Institute of Technology, Guwahati.
Eurocopter EC155-B

2. Road Map
General Information About EC155
Turboshaft Engine (Turbomeca Arriel 2C1)
Specifications of the Engine
Specifications of the Helicopter
Aerodynamics & Performance of the
Helicopter

3. Medium Multi-mission Helicopter
Comfortable and Fast
Passenger Transport
VIP, Corporates, Police, Public Service
Emergency medical service.

4. Spacious Cabin
1-2 Pilots
5-12 Passengers
State of art glass cockpit.
Standard 4-axis autopilot &
Ergonomically placed flight.

7. Specifications of the
Engine:
Length: 112 cm
Diameter: 60 cm
Dry weight: 111 Kg
Compressor: Single-stage axial
plus single-stage centrifugal.
Combustor: Annular combustion
chamber.
Turbines: Single-stage power
turbine, Single-stage gas
generator turbine.
Maximum power output: 681
shp (508 KW).
Turbine inlet temperature: 840
C.
Power-to-weight ratio:
5KW/Kg.

8. Single-stage
Axial
Compressor
Single-stage
Centrifugal
Compressor

9. High Pressure, Gas
Generating, Single-
stage Turbine
Low Pressure, Power
Generating Single-
stage Turbine

10. Annular
Combustio
n
Chamber

11. Specifications of the
Helicopter:
Capacity: 2,301 Kg payload
Length: 14.3 m
Height: 4.35 m
Empty weight: 2,618 Kg
Gross weight: 4,950 Kg
Max takeoff weight: 4,920 Kg
Powerplant: 2 × Turbomeca Arriel 2C2
turboshaft engines.
Main rotor diameter: 12.6 m
Main rotor area: 124.7 sq m
Never exceed speed: 324 Km/hr
Range: 857 Km
Ferry range: 985 Km
Service ceiling: 4,572 m
Rate of climb: 8.9 m/s

12. EC155-B Helicopter has
a maximum speed of
324 Km/hr, and can fly at
a fast cruise speed of
278 Km/hr at an altitude
of 6000 ft.
Efficient lift and the high
top speed are attributed
to its high efficiency
profile.

13. • Five-bladed Spheriflex main rotor with an extremely low vibration
level.
• The EC155B is also said (by its makers) to be the only helicopter
in its class to offer an optional de-icing system.
• The shrouded Fenestron tail rotor has ten blades asymmetrically
spaced around the hub.

14. 1-
Torque:

15. Anti-Torque
System

16. 2- Lift:
Lift is produced due to the airflow from the upper
surface of main rotor to the bottom surface, or simply,
Downwash.
Video

17. Asymmetry of Lift
The advancing blades
travel faster than the
retreating blades, so, they
generate more lift.
And that’s why the
helicopters tend to veer up
to one side.

18. Retreating blades stall
In order to compensate the
lift reduction in the
retreating area, the angle of
attack of the retreating
blade must be increased.
Increasing the angle of
attack too much results in a
stall.
The blade stalls and then
unstalls as it moves
through this region.

19. 3- Three Axes of
Flight:
Vertical Axis (Yawing)
Controlled by the tail rotor

20. Logitudinal Axis (Rolling)
Controlled by the cyclic:
A stick in the cockpit, changes
the pitching angle of the main
rotor.

21. Lateral Axis (Pitching)
Also controlled by the cyclic

22. 4- Forward & Backward
Flight:
Controlled by pitching
angle.
In forward flight, the rotor
disc is tilted downwards.
In backward flight, the
rotor disc is tilted
upwards.
Hence, the total lift will
has two components.

23. 5- Hover:
IGE: In Ground
Effect
OGE: Out of Ground
Effect