Helicopter Downwash Rig


To simulate a realistic plume from a helicopter exhaust, it is sometimes necessary to provide a downwash from the rotor blades. S & C have developed a series of 168 Coanda ringjet ejectors which are fed from the Gnome turboshaft 1 compressor flow. These ejectors allow jets of compressor flow to entrain large quantities of ambient air and turn through 90 degrees, resulting in a large downwash footprint. The rig can to flight stream rig allows a simulation of propulsion systems under dynamic testing. The system uses the compressed air flow from the Gnome turboshaft rigs, which is fed through a twin ejector system to entrain large amounts of ambient air. This is settled in a large plenum chamber before it exits via a large nozzle which comprises the working section.


  • Average downwash velocity 12.52m/s
  • Max temperature 14.3ºC above ambient (1m below nozzle exit)
  • Turbulence levels approx 20%
  • Working area 2.4 x 1.35m
  • Adjustable height above test article


  • Rotor blade flow
  • Tailwind or side wind

Traverse rig >

© S & C Thermofluids Ltd 2024

S & C Thermofluids Ltd

The Old Tannery, Kelston, Bath, BA1 9AN
Tel: 0117 932 7378 Fax: 0117 932 9652
Email: tony.smith@thermofluids.co.uk