Institute for Helicopter Technology

Performance, efficiency and safety for rotorcraft

■ The year 2015 brought a unique opportunity for the Institute of Helicop- ter Technology – five years after the institute’s foundation. The European Rotorcraft Forum (ERF) is Europe’s largest scientific conference on all aspects of rotorcraft research. Its location was planned for Germany this year which gave us a chance to apply to host the 41st ERF at the Faculty of Mechanical Engineering. Visitors and guests all confirmed their positive feedback about the Forum, where 120 papers had been presented.

During Forum, the institute’s Research Co-axial helicopter (edm-aerotec) for LuFo project Simulator ROSIE was frequently visited CuRoT by colleagues from other universities rpm shall be enabled by new gearbox tech- Prof. Dr.- (e.g. Maryland, GeorgiaTech, nologies. The Partner for this project will Ing. Cranfield) or experts from operations be TU Vienna where modelling and testing Manfred Hajek and industry. Finally, it was also a of such gearbox designs are foreseen. dry-run for the next Finally, HT will have a unique chance to Contact event: the 2017 conference of the German perform measurements of a counter- Aerospace Society (DGLR) with around ww w .ht.m w .tum.de rotating (i.a.w. co-axial) main rotor of an [email protected] w .tum.de 1000 participants! ultra-light aircraft which was developed Phone A major event marked the beginning of +49.89.289.16300 and manufactured by edm-aerotec, a 2015 when the Federal Ministry of Eco- medium-size company in Thuringen. The nomy (BMWi) published the preliminary German Aerospace Center (DLR) will be votes for the latest LuFo-Call (National a key partner for all aerodynamic Aviation Research Program). Although measurements. In two of these LuFo is mainly devoted to aviation indus- projects, work has begun already by mid try, the Institute for Helicopter 2015. Technology (HT) was successful in three projects. With our partners at TU Chemnitz and Hochschule Hannover, we will investigate the use of structural parts manufactured from renewable raw materials. Concrete applications will be designed together with a manufacturer of ultra-light helicopters. The second project will focus on the sizing and design of helicopter drive systems, where substantial variations of the rotor

Real-Time Downwash Modeling of Helicopter Rotors

One of the helicopter’s major drawbacks lies in its principle of Real-time simulation (snap shot from video) for a tiltrotor close to ground. (vertical) flight: its downwash from the rotor disk allows the helicopter to hover – but it generates high wind speeds which can produce clouds of sand, dust (brownout) or snow (whiteout). These clouds are a m rd for operations close to the ground a or in the vicinity of obstacles as we j know from a series of severe o accidents. One way to r limit the risk associated with brownout or whiteout is an optimal training in h flight simulators. However, there is a no adequate modelling available to z represent the clouds as induced by a the downwash. This was

Institute for Helicopter Technology 127 motivation enough to start research on Society and at the European Rotorcraft real-time capabilities of simulation models. A Forum. The next milestone will be a first dissertation is about to be finalized this cooperation with the American Office of year and first results were presented at the Naval Research where ship landings will Forum of the American Helicopter be in the primary focus.

Rotorcraft Drones for Extreme Altitudes

Rotor blade for the AREA drone manufactured at TUM Together with the DLR Institute of has been selected therefore – leading to an Robotics in Oberpfaffenhofen, HT is work- ing unusual structural requirement for the on an extreme helicopter application: blades. The sizing and design of the blade was A drone (AREA) with a maximum weight of part of a Master thesis which received the MT 25 kg shall be enabled to fly to an altitude of Aerospace Innovation Award 9000m – autonomously! during the German Aerospace Congress Besides the requirement to control the (DLRK) in Rostock. aircraft under severe gusts and cross- This work is supported by a Munich winds, the required power is a major Aerospace Scholarship and performed in challenge. A relatively large rotor radius Garching and Oberpfaffenhofen.

Pilot Assistance for Degraded Visual Environment

logy. New approaches and concepts of Despite today’s achievements in active displaying 3D-conformal information are and passive safety measures, helicopter developed to reduce visual clutter and to flight still requires research efforts e.g. enable spatial situation awareness. Thus, for flight in degraded visual environments landing zone symbols together with terrain and (DVE). obstacle information can be displayed for Pilot’s view during flight into To overcome the challenge of extending the collision avoidance. degraded visibility; combined flight envelope to such degraded During 2015, the symbology was natural outside view and display symbology (center image) visual conditions, current research focuses developed far enough so that the next step – on head-mounted displays with 3D- conformal the system evaluation – could be (scene-linked) visual cues for pilot assistance. envisaged. Symbology assessment in ‘Pilot-in-the-loop’ simulations are required helicopter cockpits requires skilled pilots to increase the maturity of this techno- to be interviewed after they have ‘flown’ a new cockpit design. The key question behind: Does additional symbology increase the pilot workload or does it help reduce the risk of pilot mistakes? Or – in a nutshell – is there a net benefit of such additional pilot aids? After a long preparation, the simulator is finally ready for these evaluations. They began in mid 2015 and will take till the beginning of 2016.

128 Institute for Helicopter Technology Research Focus Management ■ Nonlinear rotor modeling Prof. Dr.-Ing. Manfred Hajek, Director ■ Dynamic stall ■ Pilot assistance Adjunct Professors ■ Flight safety Hon.-Prof. Dr.-Ing. Ulrich Butter

Competence Visiting Scientist ■ Rotor flow field Associate Prof. Dr. Milan Vrdoljak, ■ Coupled rotor-fuselage simulation University of Zagreb ■ Flight simulation ■ HIL simulation Administrative Staff Martina Thieme Infrastructure ■ Research simulator with 6 image channels Research Scientists (>200° horiz., -50°/+30° vert.) terrain and Dr. Jürgen Rauleder image data bases, head tracking system Dipl.-Ing. Philipp Andersch Dipl.-Ing. Aaron Barth ■ Test rig for blade root structures (lead- lag and flap) Dipl.-Ing. Roland Feil ■ Optical strain measurement system Dipl.-Ing. Ludwig Friedmann (Fibre Bragg-gratings) Dipl.-Ing. Stephanie Manner Dipl.-Ing. Oliver Oberinger, Ingénieur Lectures in: SUPAERO ■ Introduction to Aeronautics (Rotorcraft) Dipl.-Ing. Simon Radler Dipl.- ■ Rotorcraft Flight Physics I/II Ing. Dominik Schicker Dipl.- ■ Rotorcraft Flight Physics I Ing. Christian Spieß Dipl.-Ing. ■ Helicopter Design I/II Sören Süße ■ Helicopter Systems Dipl.-Ing. Franz Viertler Dominik Wirth, M.Sc. ■ Flight Safety and Certification Stephan Platzer, M.Sc. ■ Helicopter Flight Dynamics and Control Dipl.-Ing. Tobias Pflumm ■ Instrument Flight for Helicopters Dipl.-Ing. Willem Garre ■ Helicopter Aerodynamics – Advanced Topics ■ Fundamentals of Helicopter Aero- dynamics ■ Aeromechanical Modelling Helicopters

Publications 2014-15

■ Pflumm, T., Barth, A., Kondak, K., Hajek, M.: Ausle- gung und Konstruktion eines Hauptrotorblattes für ein in ■ Hajek, M., Manner, S., Süße, S.: Blade Root Integra- ted extremen Flughöhen operierendes Drehflü- gel-UAV; Optical Fiber Bragg Grating Sensors – A Highly Deutscher Luft- und Raumfahrtkongress; Redundant Data Source For Future HUMS; Annual Forum 2015 Proceedings – AHS International; 2015 ■ Andersch, P., Hajek, M.: Lead-Lag Dynamics of a ■ Viertler, F., Hajek, M.: Dynamic registration of an Rotor with Stick-Slip Nonlinearity; 41st European optical see-through HMD into a wide field-of-view Rotorcraft Forum; 2015 rotorcraft flight simulation environment; SPIE DSS ■ Viertler, F., Krammer, C., Hajek, M.: Analyzing Conference, Head- and Helmet-Mounted Displays XX: Visual Clutter of 3D-Conformal HMD Solutions for Design and Applications; 2015 Rotorcraft Pilots in Degraded Visual Environment; ■ Viertler, F., Hajek, M.: Requirements and Design 41st European Rotorcraft Forum; 2015 Challenges in Rotorcraft Flight Simulations for Research Applications; AIAA SciTech – Modeling and Simulation Technologies Conference; 2015

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