2006-12-31T03:35:00.000-08:00

X-Hawk Stabilizer Structural Design and Analysis

AFEKA PR ME DE JL TL1-4050 Motor vehicles. Aeronautics. Astronautics

הוגש ע"י

יעקב ליבשיץ ,עבודת גמר ב אפקה המכללה האקדמית להנדסה בת"א , הנדסת מכונות ומערכות

Submitted by

Jacob Livshits, Final Project -Mechanical and Systems Engineering AFEKA Tel-Aviv academic college of engineering

מנחה

ד"ר רפי יואלי.

Advisor

Dr. Rafi Yoeli, URBAN Aeronautics, www.urbanaero.com

תמצית
הפרוייקט הינו תכנון מפורט ומלא של מערכת המייצב של כלי תעופה אורבני. התכנון משתמש בחומרים מרוכבים, ומבוסס על דרישות חוזק ומשקל קשיחות ביותר.

Abstract

The X-Hawk is a VTOL (Vertical Take-Off and Landing) rotor based aircraft invented
by Dr. Rafi Yoeli, from URBAN. The project scope is the design and analysis of the
stabilizer assembly. The stabilizer is required for the following:
• Generates additional lift force under cruising flight conditions.
• Stabilizes the pitch of the airplane.
• Provides attachment of control surfaces.
The project of the X-Hawk Stabilizer Analysis and Design is focused on two primary
tasks: the detailed design and the weight optimization of the stabilizer structure, and the
schematic design of manufacturing tooling and processes required to produce the stabilizer
assembly. The stabilizer external envelope was given along with the loads applies on
the structure, while the project was to design and choose the structural elements, their
locations and quantity. The design included construction optimization, including weight,
stress, and stiffness restrictions and requirements, selection of materials and material
technology that meets the design and minimum cost requirements, selection and design
of the manufacturing tooling considering the net trim manufacturing approach. This
approach is based on the idea that the complete, ready for installation part/assembly is
produced on a single tool without any need for trimming. With this method, the highest
level of repeatability is achieved together with high accuracy and high effective properties
of the manufactured product, primarily due to lesser amount of assembly effort. The parts
produced by this method usually have better fatigue performance due to lesser fastening
required.
The design utilizes the most advances materials in the aerospace industry - composites.
The materials and their manufacturing process are presented in detail for better
understanding of the choice of the materials, as well as the complexity of the design and
manufacturing process.
The Project workflow consisted of the following steps:

1. Research and presentation of the general types of solutions available in today’s practice
for creation of structurally sound wing designs, according to technical references
[REF11], [REF12], [REF 3] and [REF 2].
2. Breakdown of the possible solutions to structural components, including Spars,
Ribs, etc..
3. Weight analysis of each structural component according to the stabilizer dimensions.
4. Evaluation of possible solutions presented in the first stage, according to the weight
estimate.
5. Manual calculation of the reactions and buckling of extremely simplified beam and
plate models.
6. Presentation of several solutions incorporating existing design elements which fits
the weight criteria.
7. Selection the configuration of structural elements, and construction of a CADmodel.
8. Analysis of the model using FE software for various loading conditions and requirements.
9. Optimization of the FE model, for compliance with both weight and strength requirements.
10. Design of the tooling for manufacturing the stabilizer assembly.

Table of Content

Contents
List of Figures 4
List of Tables 7
1 Abstract 8
2 General Description and Requirements 10
2.1 Overview of the Stabilizer andX-Hawk . . . . . . . . . . . . . . . . . . . 10
2.2 ProjectGoals andRequirements . . . . . . . . . . . . . . . . . . . . . . . 15
2.3 Geometrical Properties of Stabilizer Assembly and Elements . . . . . . . 15
3 Design Loads and General requirements 21
3.1 Aerodynamic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1.1 Airfoil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2 Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2.1 Stabilizer Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2.2 Nacelle Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3 Loads Calculation Procedure andMethodology. . . . . . . . . . . . . . . 24
3.3.1 Hand Calculation of the Stabilizer Reactions and Buckling . . . . 25
Calculation of the reaction and deflection of the Stabilizer . . . . 25
Buckling of a Skin-only Configuration . . . . . . . . . . . . . . . . 27
4 Introduction to Composite Materials and Manufacturing 29
4.1 Overview ofMaterials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 Overview ofManufacturing Process . . . . . . . . . . . . . . . . . . . . . 31
4.2.1 Wet/Hand Lay-up . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2.2 PREPREG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2.3 VacuumBagging . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5 Design Alternatives 37
5.1 PossibleDesignAlternatives . . . . . . . . . . . . . . . . . . . . . . . . . 38
6 Material and Design Elements Definitions 43
6.1 Structural Design Elements . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2 Material Properties for the PreliminaryDesign Phase . . . . . . . . . . . 46
6.2.1 Carbon/Epoxy PREPREG. . . . . . . . . . . . . . . . . . . . . . 46
6.2.2 Honeycomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.2.3 ROHACELL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7 Analysis of Selected Alternatives 49
7.1 Alternative StabilizerDesigns . . . . . . . . . . . . . . . . . . . . . . . . 49
7.1.1 Alternative 1. Spars, Stiffeners, andRibs . . . . . . . . . . . . . . 49
7.1.2 Alternative 2. Spars, Ribs, Trailing and Leading Edges . . . . . . 51
7.2 Alternative NacelleDesigns . . . . . . . . . . . . . . . . . . . . . . . . . 52
8 Theoretical Background and Finite Element Model Presentation 54
8.1 Finite Element Model Description . . . . . . . . . . . . . . . . . . . . . . 54
8.1.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.1.2 Loads Applied to the Finite ElementModel . . . . . . . . . . . . 57
Loads on the Stabilizer . . . . . . . . . . . . . . . . . . . . . . . . 57
LoadsGenerated by the Forward ThrustUnit (FTU) . . . . . . . 58
General Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.1.3 Material Properties in the Finite ElementModel . . . . . . . . . . 59
8.2 Analysis Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
8.3 Element Properties Configurations and Weight Characteristics . . . . . . 60
8.4 Buckling analysis of panels in compression field . . . . . . . . . . . . . . 61
8.4.1 General comments . . . . . . . . . . . . . . . . . . . . . . . . . . 61
8.4.2 Typical analytical procedure in buckling analysis withMSC/NASTRAN 63
8.4.3 Method to analyze the lower surface of the stabilizer for buckling. 64
8.4.4 Finite element analysis example of buckling of a simple plate. . . 65
9 Finite Element Analysis of Stabilizer Assembly 68
9.1 Analysis of the Starting-point Configuration . . . . . . . . . . . . . . . . 68
9.1.1 Model Description . . . . . . . . . . . . . . . . . . . . . . . . . . 69
9.1.2 Analysis Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
9.1.3 Weight Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
9.1.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
9.2 Analysis of HighlyHoneycomb Reinforced Stabilizer. . . . . . . . . . . . 74
9.2.1 Model Description . . . . . . . . . . . . . . . . . . . . . . . . . . 74
9.2.2 Analysis results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
9.2.3 Weight Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
9.2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
9.3 Control Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
9.4 Analysis Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
10 Production Process and costs 82
10.1 StabilizerManufacturingModel Description . . . . . . . . . . . . . . . . 84
10.2 Manufacturing Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . 87
10.3 Manufacturing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Summary 91
A Aerodynamic Analysis 92
A.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
A.2 Simple Analysis of the NACA0012Airfoil . . . . . . . . . . . . . . . . . . 93
B Material Properties 95
B.1 Carbon Epoxy Cloth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
B.2 Carbon Epoxy Prepreg . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
B.3 ROHACELL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
B.4 Honeycomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
B.5 Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Bibliography 103

מילות מפתח

חומרים מרוכבים, אנליזת חוזק, קריסה, כלי תעופה

Keywords

X-Hawk, Analysis, Finite Elements, Aeronautics

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X-Hawk Project