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

A simplified model for evaluating eVTOL conceptual designs and with example results for three types of eVTOL aircraft configurations
Yip, S.L.K.; Hoong, A.K.J.; Wang, J.
eVTOL Performance Analysis Tool, known as ePERF is a MATLAB-based analysis developed at NTU specifically for evaluating the performance of different types of eVTOL aircraft and is ideal for eVTOL aircraft conceptual and preliminary design phases. The framework is built to have a modular nature allowing for rapid trade studies of different sizing parameters, and it provides a representative performance evaluation of the eVTOL in all phases of flight. ePERF consists of three main modules: a rotary wing module, a drag estimation module for forward flight and an energy module for range calculation. Momentum theory is used for hover calculations. A component level drag build-up method is used for cruise calculations. The energy model considers the input battery parameters and results from the other two modules to compute the energy requirements of the eVTOL based on a given mission profile. The outputs of ePERF include the power and energy requirements for each flight phase, an estimated attainable range, as well as the velocity for best range. In this paper, the ePERF is explained and then it is used to estimate the performance for three different example eVTOL aircraft: (A) a Lift + Cruise type like Beta Technologies - Alia, (B) a tiltrotor type like Joby Aviation - S4, and (C) a fixed Lift + Tiltrotor type like Vertical Aerospace - VX4. The results show that reducing the structural weight of the eVTOL aircraft is one of the key factors in achieving best performance.
Manufacturing of a variable chord extension concept for helicopter rotor blades with a flexible EPDM skin
Kalow, S.; Riemenschneider, J.; Balzarek, C.; Mendrock, T.
In the SABRE project a new morphing concept, the so-called linear variable chord extension, has been devel-oped. Here, the blade chord length in the root area is changed with the help of an elastic skin to adapt it to the respective flight condition. This paper focuses on the manufacturing process of the technology demonstrator and give a detailed overview about the advantages and disadvantages of handling with EPDM material. This also addresses the challenge of reinforcing the EPDM with CFRP fibers.
Generic eVTOL aircraft preliminary sizing method for AAM/UAM missions
Kahn, Y.M.; Balli, M.E.; Trainelli, L.
Advanced Air Mobility (AAM) or Urban Air Mobility (UAM) presents many challenges to the aircraft design. The concept not only requires operations over urban airspace but also without the use of traditional airports with long runways. Additionally, the new aircraft designs must do so on electric power as much as possible with low chemical and noise emissions. Hence the term electric vertical takeoff and landing or eVTOL is popularized. This paper presents a novel method for preliminary sizing of eVTOL aircraft of arbitrary architecture. The methodology allows the conceptual analysis and initial trade-off studies independent of the aircraft configuration. Aircraft is considered as the sum of building blocks like rotors, propellers, wings, and several other subsystems contributing to mass, energy, power and drag estimates. Results from this study permit a quick evaluation of configurations and missions with an inevitable degree of approximation. Finally, the main features of the method are discussed in the paper with a relevant validation exercise for various eVTOL aircraft considering mass and other performance metrics.
Comparison of optimization based inverse simulation methods for helicopter maneuvers
Tosun, F.; Kalkan, U.
In a helicopter certification process, aviation safety agencies want to be sure that the helicopter can safely fly all maneuvers defined in its usage spectrum. Therefore, loads engineers carry out all these maneuvers for each appropriate combination of weight and center of gravity. Moreover, this maneuvering and load analysis process should be performed in the most efficient way. For this reason, this article works on two different algorithms, the gradient-based Symmetric Rank-One (SR1) and commercial optimization tool Siemens HEEDS, to perform desired helicopter maneuvers. In this study, helicopter pushover maneuver is carried out and the results for each algorithm are compared as an example. However, different maneuver results are also added to show applicability of the solution algorithms. Furthermore, rotorcraft simulation and modelling software FLIGHTLAB is used to simulate the maneuver. Rotorcraft is modeled as rigid and uniform inflow is used for the calculation of rotor aerodynamic loads.
Are eVTOL aircraft inherently more susceptible to the vortex ring state than conventional helicopters?
Brown, R.E.
There is currently extensive interest worldwide in developing small, lightweight, electrically powered, multi-rotor vertical takeoff and landing aircraft. The aim is to use these new vehicles to carry a small number of passengers on short-range intra-urban missions, for instance as part of a passenger ferry service between an airport and a downtown commuter hub. The concern is that these aircraft might have certain characteristic design features that, in combination with the environmental conditions that they will experience, will render them particularly susceptible to a potentially hazardous operating regime, known as the Vortex Ring State, especially during their descent and landing. This paper extends our classical understanding of the basic physics that underpins the Vortex Ring State in order to assess the likely impact of this phenomenon on the safety and operational characteristics of this new class of vehicle.