Freefall Simulation Systems

There is three different basic systems of freefall simulation that are distinguished according to the routing of the airflow.:

• Closed vertical windtunnels recirculating the air in a ring-shaped air duct („Recirculator“).
• Open vertical windtunnels with an air suction from the outside at the lower end of the air duct and an air emission to the outside at the upper end of the air duct („Open-flow“).
• Outdoor facilities with an open flight area above net-protected fans. The open flight area is protected by safety cushions.

Recirculators have a ring-shaped air duct. After sucking the air above the flight chamber in, diffusors recirculate the air to the fans. Recirculators may be operated independent of wind and weather, particularly outside temperatures and have significantly lower noise levels than open-flows and outdoor facilities. Year-round operations, energy efficiency and low noise levels are clear advantages.

Due to the low noise levels, high quality recirculators may even be operated in the neighbourhood of residential areas. Compared to any other system, the turbulences in recirculators are hardly noticeable. Consequently, the facility is likewise suitable for the entertainment industry and professional skydivers. Freefall is simulated at realistic conditions. The first recirculator worldwide opened in 2005. To our knowledge, there are currently four recognized vertical windtunnel manufacturers for closed systems worldwide.

Bottrop, Germany

Eloy, Arizona, USA Open-flow systems have an open air duct on either side. Open-flow systems suck air from the outside, press the air through the flight chamber and emit the air at the upper end of the air duct into the open. Open-flow systems are weather dependant and noisy. Wind, rain, outside temperature, dust and dirt may disrupt the facilities operation. Year-round operations are limited to areas with low outside temperatures. Due to the relatively high noise level, building and other permits are often either limited to remote areas or subject to vast exemptions. Compared to recirculators, open-flow systems usually have lower construction costs. The first open-flow system opened 1998. To our knowledge there is one recognized manufacturer worldwide.

Rümlang, Switzerland Outdoor facilities are the low construction cost alternative. They are available as mobile and stationary systems. Outdoor facilities have no air duct in a traditional sense. The open air stream is generated by a net-protected fan, that blows the air into the open flight section. In case flyers drop out of the air stream they are protected by safety cushions. The risk of injury in outdoor facilities is significantly higher compared to indoor systems. There is hardly any sound insulation possible. Outdoor facilities provide for noise levels >120 db. Outdoor facilities are to a significant extent weather dependent and usually operated as seasonal business. Outdoor facilities have a significant energy consumption. None of the existing outdoor facilities has a suffienctly strong air stream for freefly training. Normally flying in outdoor facilities requires an extra-large suit and is limited to belly flying only. The air stream in outdoor facilities may provide for heavy turbulences. Turbulences make flying difficult and hinder professional training to a large extent. Outdoor facilities do not provide for a realistic freefall simulation. The first outdoor facility was developed in the sixties of the last century. As outdoor facilities are not technology driven, numerous manufacturers exist worldwide.