DSpace Repository

The ERF

The European Rotorcraft Forum is one of the premier events in the rotorcraft community’s calendar bringing together manufacturers, research establishments, academia, operators and regulatory agencies to discuss advances in research, development, design, manufacturing, testing and operation of rotorcraft.

The ERF International Committee is providing free access to the available papers presented at the past ERF conferences. Two years after each ERF, the conference papers are uploaded to the repository.

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ERF
European Rotorcraft Forum

Recent Submissions

Fundamental Understanding Of Helicopter Rotor Hub Vibration Reduction Using Non-Structural Lumped Masses
(2024) Majeti, R.K.; Turumella, A.Y.
Significant potential exists for reducing the vibratory hub loads generated by the rotor through optimal blade design process. An optimization study was carried out to reduce the vibratory rotor hub loads using non-structural lumped masses and twist. The lumped masses had both spanwise and chordwise location variability. Prior to the optimization, a sensitivity analysis was carried out to understand the effect of the individual parameters on the vibration index. A significant observation from the study was that a lumped mass which was placed near the tip region and aft of the elastic axis reduces the vibration index the most. Optimally locating three lumped masses along with optimal twist led to a reduction of vibration index by 65% from the baseline case. Such a significant reduction was achieved without resorting to radical design or geometries and without expensive techniques.
Fuselage Vibration Reduction Of Lift-Offset Coaxial Rotor Vehicles With Auxiliary Propulsion Via Individual Blade Pitch Control (Ibc)
(2024) Mawry, I.; Smith, E.; Schmitz, S.; Zhang, J.; Park, J.S.
The present study investigates the fuselage vibration reduction potential for a lift-offset coaxial rotor vehicle with auxiliary propulsion using open-loop individual blade pitch control (IBC) applied to the main rotor. The comprehensive aeroelastic software, Rotorcraft Comprehensive Analysis System (RCAS), was utilized to implement the XH-59A elastic-line fuselage model and create a comprehensive coupled rotor-fuselage model for analysis. An open-loop IBC phase sweep was applied to the main rotor at 200 knots and reduced the 3/rev and 6/rev hub loads and cockpit vibrations. For a 3/rev, 1° IBC amplitude at 270° phase, the reductions in the 3/rev hub loads for this input were 89% in ??!, 48% in ??", and 79% in ??#. Additionally, the cockpit vibrations decreased by 81% in the longitudinal direction and 76% in the vertical direction for the 3P/1°/270° IBC input. The 6/rev hub loads and cockpit vibrations were also reduced with various open-loop IBC inputs.
Alternative Propulsion System For Helicopter And Co2 Emissions
(2024) Beddok, S.; Jarin, J.B.
The aviation sector is now facing one of its biggest challenges as it aims to reduce its carbon emissions close to zero and decarbonization of air mobility requires to lower the carbon intensity of its energy. Several technologies are potential candidates both at aircraft level, including configurations and at propulsion system level, including architectures and energy sources. Biofuels will, of course, play an important role, but other low carbon energy carriers based on electricity will be also considered. This study focuses on small helicopter aircraft and on propulsion system by looking at the six main propulsion systems known as conventional turboshaft engine with either standard jet fuel, sustainable aviation fuel or electro fuel issued from hydrogen or direct hydrogen combustion, full electric supplied by batteries and full electric supplied by fuel cell and hydrogen. Each energy has its own conversion steps and losses and its own integration effects. Hence, the aircraft will be sized for a given mission, depending on the propulsion system weight and efficiency and each solution will be compared with respects to energy consumption. Then the different energy will expressed in CO2 emissions using the Well To Wake methodology that will lead to significant differences in greenhouse gas emissions and electricity needs. We will focused how the electricity carbon intensity will affects the CO2 emissions of an air mobility mission.
High-Fidelity Cfd Maneuver Simulation Using Blade Dynamics, Flight Mechanics And A Pilot Model
(2024) Keßler, M.
High-fidelity CFD simulations for stationary flight have become state of the art for many years now, including fluidstructure coupling to blade dynamics and flight mechanics to reach a trimmed state. Unsteady maneuver simulations utilizing CFD are much more scarce, mainly due to the huge computational effort required to run for serveral tens or hundreds of revolutions, and thus more often rely on mid-fidelity aerodynamics. Continuous advances in High Performance Computing now allow the application of CFD to relevant macroscopic maneuvers, allowing an investigation of scenarios for example like vortex ring state, which are highly affected by interactional dynamics, and where midfidelity tools are less robust and reliable. The paper describes the challenges and possible solutions when progressing a well-established high-fidelity CFD framework from stationary flight to unsteady maneuvers, analyzing the physical causes of problems encountered, and further objectives to be addressed. Examples given for a Robinson R44 helicopter model include a slalom flight, a quickstop maneuver, and vortex ring state, including several evasive methods.
Evaluation Of The Representativeness Of Flight Mechanics Models During Vortex-Ring-State Entries And Recovery Manoeuvres
(2024) Binet, L.; Cornefert, T.
Vortex-Ring-State (VRS) remains a dangerous regime leading to several accidents every year. Many studies have been conducted on the phenomenon, but the representativeness of flight mechanics models for prediction of the vortex ring boundaries, and their capability to reproduce the helicopter behaviour during VRS and recovery manoeuvres is still questionable. Therefore, developing fast numerical models able to reproduce this specific aerodynamic rotor regime and validating their representativeness compared to flight tests is an important task to train pilots to VRS in real-time simulator. The 'VRS-Helicopter Vortex Ring State Experimental Research', led by EASA and bounded by a contract signed between the EASA and ONERA/DGA-EV, aims to enhance understanding of VRS across two helicopters types, exploring analytical, simulation, and flight test methods. Additionally, it assesses the different recovery manoeuvres. As part of the objectives of this project, the main subject of the paper is to evaluate the correctness of flight mechanics code, VRS models and the reproducibility of recovery techniques. Off-line simulations are compared against flight test data, gathered from the eight flights performed during this project. Additionally, simulator trials were realized in the ONERA research simulator in order to evaluate the representativeness of two different VRS models through piloted simulations. The objective is to highlight the potential shortcomings of the VRS models and thus the reservations to be taken into account when the vortex phenomenon and associated recovery techniques are evaluated through simulations.