VRS (Helicopter Vortex Ring State Experimental Research)

The research objectives and expected outcome

The Certification Specifications today in force for helicopter certification do not require the applicant to determine those conditions in order to achieve type certification of the product neither to include relevant information in the Rotorcraft Flight Manual. In addition, although the VRS is nowadays included in the training regulation (AMC2 to Part-FCL.210 ), as one element of the syllabus for the private pilot licence for helicopters (PPL-H), the recovery manoeuvre being taught to student pilots is mostly limited to the traditional ones. 

The outcome of the research will therefore be twofold. On the one hand, it will provide a better understanding of the VRS phenomenon on different kinds of helicopters, the analytical and simulation prediction methods, and flight test methods for its determination. On the other hand, it will provide an indication of the effectiveness of other recovery manoeuvres such as the one proposed by Capt. Vuichard.

The above-described outcome will be a key element for the Agency in the assessment of the need for possible changes to the certification specifications, pilot training regulations and associated guidance material. 

The requested output

The following outcome will be required with this experimental research:

  1. To experimentally determine the flight conditions at which the VRS starts to develop for at least two different types of helicopters to support and evaluate the correctness of theoretical methods for prediction of the vortex ring boundaries.
  2. To experimentally evaluate the effectiveness of the Vuichard recovery technique for at least two different types of helicopters.

The experimental research programme shall include an experimental flight test activity on at least two different helicopter types having different kinds of main rotor systems. The test aircraft shall be instrumented with sensors capable of measuring real-time flight and system parameters appropriate for the scope and objectives of the flight test programme. Real-time monitoring of the parameters shall be provided either on board or, preferably, transmitted to a ground control station. Parameters shall be also recorded for post-flight data analysis.