The Icing Wind Tunnel (IWT) is a climatic facility with a very long test section (100m) for non-icing rotorcraft climatic tests. In 2013 RTA completed and commissioned an icing spray bar system and calibration equipment for use in the largeCWT. Since 2020 the icing facility can also be operated in the smallCWT. The facility can be used to test full-scale tail rotors installed on a helicopter and components on a rotorcraft fuselage in icing conditions, as well as rotorcraft full-scale and scaled components.

Test Setup 1:  cross section 16.1m²

Icing section width / height     3.5m / 4.6m 

Icing cross section              16.1 m²

LWC temperature range      -2°C to -30°C

LWC droplet size range       15 µm to 40 µm

Air and water pressure       0 to 10 bar

Water flow                           0 to 4 l/min

Wind speed (SWT)             10 m/s to 20m/s

Wind speed (LWT)             10 m/s to 20m/s


Test Setup 2:  cross section 8.75m²

Icing section width / height     3.5 m / 2.5 m

Icing cross section              8.75 m² (with additional contraction nozzle)

LWC temperature range     -2°C to -30°C

LWC droplet size range      15 µm to 40 µm

Air and water pressure      0 to 10 bar

Water flow                          0 to 4 l/min

Wind speed (SWT)            20 m/s to 40m/s

Wind speed (LWT)            20 m/s to 80m/s


Globally Unique Test Facility

Given the size and high cooling capacity of the Vienna Climatic Wind Tunnel, the icing rig provides the only opportunity in the world to test engines of up to 1800 HP at full throttle.

This is particularly significant because the formation of ice has a substantial influence on the performance of the engine and therefore realistic conclusions can only be drawn when the engine is in operation. Without the contraction nozzle, the icing cross-section can even be extended to 16 m² at reduced ‘flight’ speeds.

This enables icing tests to be carried out on whole helicopters, making the Vienna Icing Wind Tunnel the biggest of its kind in the world.


Certification for Aviation

Safety is naturally a top priority in the aviation industry. When an aircraft flies through the upper cloud layers, super-cooled water droplets suddenly freeze and in just a few minutes form a centimetre thick layer of ice on critical components such as the engines, rotors, wings and sensors. In order to obtain certification for these components and the aircraft as a whole, manufacturers must demonstrate that sufficient protective measures have been implemented against icing and that the formation of ice will not endanger flight safety in any way.

In order to develop, test and certify its products, the aviation industry therefore urgently requires high-performance facilities where suitable icing tests can be carried out. Rail Tec Arsenal has taken on this challenge and invested around € 1.15 million in its new icing facility. Thanks to this mobile icing rig, the longest climatic wind tunnel in the world can now be converted into the world’s largest icing wind tunnel for aircraft.


Cloud Simulation at Ground Level

Certification tests involve a simulation of different cloud types with water droplets of 15 µm to 40 µm and temperatures between -2°C and -30°C. One of the greatest challenges is to ensure that the water droplets remain liquid at subzero temperatures, as they do in layers of high cloud. This ‘cloud formation at ground level’ is achieved using elaborate water treatment and complex air pressure and system control.

The mobile icing rig consists of 11 bars and a total of 264 nozzles as well as a contraction nozzle which is introduced into the large or small climatic wind tunnel for the icing tests. This arrangement enables icing tests to be carried out at speeds of around 300 km/h in a cross-section of 8.75 m². This allows critical ice accumulations on the engines, rotors and wings of helicopters or small aircraft to be investigated under real flight conditions.