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Concept of a variable chord-extension

Balzarek, Christoph and Riemenschneider, Johannes and Majeti, Rohin Kumar (2020) Concept of a variable chord-extension. In: 46th European Rotorcraft Forum, ERF 2020, 1 (1), pp. 113-122. Curran Associates, Inc. ( Mar 2021 ). ERF 2020, 08.-11.Sep-2020, Moskau. ISBN 978-171382358-2.

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Abstract

Among all kinds of aircraft, helicopters are standing out due to their capability for both forward flight and hovering. Thisrange of flight conditions requires a special blade design, resulting in a rotor blade geometry, which represents acompromise between the different flight conditions. Morphing rotor blades could address this issue, by changing the rotorblade shape according to the demands of the current flight state. From rotor dynamic calculations it is known, that longerchord length at the blade root and increased pre-twist would increase the performance in hover [1,3], whereas shorter chordand less twist are beneficial for fast forward flight.Based on this assumption, a structural concept has been worked out for a blade design with a variable chord length in therotor root region. The model, which belongs to that concept forms the basis of a performance calculation.The structural concept consists of a pivot point at around 60% R and the chord extension is linearly increasing all theway to the blade root at 22% R. In this region an auxiliary spar is dividing the blade into a conventional rigid front part and amorphing rear part, whose structural design is the main focus of this paper. It consists of two components: a flexible skinmade of rubber-like EPDM material, which is reinforced in the spanwise direction by fibers, as well as an inner supportstructure.The design drivers for the skin thickness are shape accuracy on one end and actuator force to extend the mechanism andstretch the skin on the other end. The underlying support structure consists of vertical GFRP extending in span wisedirection. Design parameters for those webs are the distance between webs, which relates to the skin design, as well as thethickness of the members, which influences the overall stiffness of the design. The publication will present a workflow, inwhich the rotor is being structurally designed coming all the way from a generic CAD model, considering cg location as wellas elastic deformation of the elastic skin and calculating

Item URL in elib:https://elib.dlr.de/143836/
Document Type:Conference or Workshop Item (Speech)
Title:Concept of a variable chord-extension
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Balzarek, Christophchristoph.balzarek (at) dlr.dehttps://orcid.org/0000-0003-4889-0340
Riemenschneider, JohannesJohannes.Riemenschneider (at) dlr.dehttps://orcid.org/0000-0001-5485-8326
Majeti, Rohin KumarRohin.Majeti (at) dlr.dehttps://orcid.org/0000-0003-0634-8051
Date:August 2020
Journal or Publication Title:46th European Rotorcraft Forum, ERF 2020
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Volume:1
Page Range:pp. 113-122
Editors:
EditorsEmailEditor's ORCID iD
Russian Helicopters, .info@rus-helicopters.comUNSPECIFIED
Publisher:Curran Associates, Inc. ( Mar 2021 )
Series Name:46th European Rotorcraft Forum (ERF 2020)
ISBN:978-171382358-2
Status:Published
Keywords:SABRE, morphing, rotor, helicopter, trailing edge, chord extension
Event Title:ERF 2020
Event Location:Moskau
Event Type:international Conference
Event Dates:08.-11.Sep-2020
Organizer:Russian Helicopters
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:rotorcraft
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - The Innovative Rotorcraft (old)
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Adaptronics
Deposited By: Balzarek, Christoph Gerhard
Deposited On:13 Sep 2021 07:33
Last Modified:17 Sep 2021 11:21

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