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ICTUS: A light, reliable and smart instrumented cradle designed for flight

12 November 2020

The Tech TP engine cradle has been designed, manufactured and qualified by VibraTec. The project, started in 2018, has been efficiently implemented in 30 months with four major objectives:

  • To design for flight and manufacture of the cradle supporting the engine and the nacelle; 
  • To provide a dedicated instrumentation of the cradle to manage loads, temperature and vibration;
  • To address the engine air flow environment; 
  • To measure operational static and dynamic engine load.

In a preliminary step, VibraTec performed a market survey to analyse the state-of-the-art of the turboprop architectures. Safety requirements and mechanical main failures have been translated in terms of mechanical loads leading to the definition of a flight envelope specification. Finally, the Tech-TP test bed environment, located in the SAFRAN Helicopter Engines facility at Tarnos, has been inspected and qualified.

Simulation of cradle deformation/displacement
Simulation of cradle deformation/displacement

Starting from these specifications, the second phase of the programme has been focused on the design of the cradle. A detailed dynamic model has been developed to predict the static and the dynamic response of the system. The analysis has covered a wide number of configuration including ultimate loads. The critical design review process was achieved at the end of 2018, opening the manufacturing process.

The cradle was manufactured with the support of the SACI Industries. Instrumented by VibraTec with strain gauges, the cradle was qualified in the VibraTec laboratory and then submitted to representative radial and axial loads. The equipment was delivered in May 2019 allowing the first TechTP run to take place in June 2019.

Cradle

The last step of the programme has been dedicated to the exploitation of the static engine test. A thermal analysis has been performed using Computational Fluid Dynamics to adjust the calibration process of the sensors, a minimal requirement to accurately monitor the TechTP demonstrator. In parallel, an inverse method has been set up to measure the operational loads of the TechTP engine. Such indirect measurements allow the characterisation of the static and dynamic forces transmitted by the engine at its mounting points. While direct methods only give access to the resulting forces, the proposed indirect method fully characterises the mechanical impact of the engine on the aircraft, a smart way to specify the engine interface without the cost of flight test. A test campaign has been conducted to deploy the methods. The full operational load characterisation of the TechTP has been extracted, analysed and delivered.

Cradle

The ICTUS programme has strongly contributed to the delivery of the first key demonstrator in Clean Sky 2 with the manufacturing of the cradle. The proposed instrumentation combined with the development of the advanced test methods offers a major breakthrough which will improve the exploitation of static engine test bed. It opens new ways to predict the engine interface within its aircraft environment for both engine and aircraft manufacturers.

The project coordinator was Vibratec and the EU contribution amounted to €272 409.38.