Small Unmanned Aircraft : Theory and Practice

637 Pages·2012·34.63 MB·English

by  Randal W. Beard

Table of Contents
Cover
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Title Page
Copyright
Dedication
List of Figures
List of Tables
Foreword
Series Preface
Preface
Acknowledgments
Part I: Introducing Fixed-Wing UAVs
Chapter 1: Preliminaries
1.1 Externally Sourced Components
1.2 Manufacturing Methods
1.3 Project DECODE
1.4 The Stages of Design
1.5 Summary
Chapter 2: Unmanned Air Vehicles
2.1 A Brief Taxonomy of UAVs
2.2 The Morphology of a UAV
2.3 Main Design Drivers
Part II: The Aircraft in More Detail
Chapter 3: Wings
3.1 Simple Wing Theory and Aerodynamic Shape
3.2 Spars
3.3 Covers
3.4 Ribs
3.5 Fuselage Attachments
3.6 Ailerons/Roll Control
3.7 Flaps
3.8 Wing Tips
3.9 Wing-housed Retractable Undercarriage
3.10 Integral Fuel Tanks
Chapter 4: Fuselages and Tails (Empennage)
4.1 Main Fuselage/Nacelle Structure
4.2 Wing Attachment
4.3 Engine and Motor Mountings
4.4 Avionics Trays
4.5 Payloads – Camera Mountings
4.6 Integral Fuel Tanks
4.7 Assembly Mechanisms and Access Hatches
4.8 Undercarriage Attachment
4.9 Tails (Empennage)
Chapter 5: Propulsion
5.1 Liquid-Fueled IC Engines
5.2 Rare-earth Brushless Electric Motors
5.3 Propellers
5.4 Engine/Motor Control
5.5 Fuel Systems
5.6 Batteries and Generators
Chapter 6: Airframe Avionics and Systems
6.1 Primary Control Transmitter and Receivers
6.2 Avionics Power Supplies
6.3 Servos
6.4 Wiring, Buses, and Boards
6.5 Autopilots
6.6 Payload Communications Systems
6.7 Ancillaries
6.8 Resilience and Redundancy
Chapter 7: Undercarriages
7.1 Wheels
7.2 Suspension
7.3 Steering
7.4 Retractable Systems
Part III: Designing UAVs
Chapter 8: The Process of Design
8.1 Goals and Constraints
8.2 Airworthiness
8.3 Likely Failure Modes
8.4 Systems Engineering
Chapter 9: Tool Selection
9.1 Geometry/CAD Codes
9.2 Concept Design
9.3 Operational Simulation and Mission Planning
9.4 Aerodynamic and Structural Analysis Codes
9.5 Design and Decision Viewing
9.6 Supporting Databases
Chapter 10: Concept Design: Initial Constraint Analysis
10.1 The Design Brief
10.2 Airframe Topology
10.3 Airframe and Powerplant Scaling via Constraint Analysis
10.4 A Parametric Constraint Analysis Report
10.5 The Combined Constraint Diagram and Its Place in the Design
Process
Chapter 11: Spreadsheet-Based Concept Design and Examples
11.1 Concept Design Algorithm
11.2 Range
11.3 Structural Loading Calculations
11.4 Weight and CoG Estimation
11.5 Longitudinal Stability
11.6 Powering and Propeller Sizing
11.7 Resulting Design: Decode-1
11.8 A Bigger Single Engine Design: Decode-2
11.9 A Twin Tractor Design: SPOTTER
Chapter 12: Preliminary Geometry Design
12.1 Preliminary Airframe Geometry and CAD
12.2 Designing Decode-1 with AirCONICS
Chapter 13: Preliminary Aerodynamic and Stability Analysis
13.1 Panel Method Solvers – XFoil and XFLR5
13.2 RANS Solvers – Fluent
13.3 Example Two-dimensional Airfoil Analysis
13.4 Example Three-dimensional Airfoil Analysis
13.5 3D Models of Simple Wings
13.6 Example Airframe Aerodynamics
Chapter 14: Preliminary Structural Analysis
14.1 Structural Modeling Using AirCONICS
14.2 Structural Analysis Using Simple Beam Theory
14.3 Finite Element Analysis (FEA)
14.4 Structural Dynamics and Aeroelasticity
14.5 Summary of Preliminary Structural Analysis
Chapter 15: Weight and Center of Gravity Control
15.1 Weight Control
15.2 Longitudinal Center of Gravity Control
Chapter 16: Experimental Testing and Validation
16.1 Wind Tunnels Tests
16.2 Airframe Load Tests
16.3 Avionics Testing
Chapter 17: Detail Design: Constructing Explicit Design Geometry
17.1 The Generation of Geometry
17.2 Fuselage
17.3 An Example UAV Assembly
17.4 3D Printed Parts
17.5 Wings
Part IV: Manufacture and Flight
Chapter 18: Manufacture
18.1 Externally Sourced Components
18.2 Three-Dimensional Printing
18.3 Hot-wire Foam Cutting
18.4 Laser Cutting
18.5 Wiring Looms
18.6 Assembly Mechanisms
18.7 Storage and Transport Cases
Chapter 19: Regulatory Approval and Documentation
19.1 Aviation Authority Requirements
19.2 System Description
19.3 Operations Manual
19.4 Safety Case
19.5 Flight Planning Manual
Chapter 20: Test Flights and Maintenance
20.1 Test Flight Planning
20.2 Test Flight Examples
20.3 Maintenance
Chapter 21: Lessons Learned
21.1 Things that Have Gone Wrong and Why
Part V: Appendices, Bibliography, and Index
Appendix A: Generic Aircraft Design Flowchart
Appendix B: Example AirCONICS Code for Decode-1
Appendix C: Worked (Manned Aircraft) Detail Design Example
C.1 Stage 1: Concept Sketches
C.2 Stage 2: Part Definition
C.3 Stage 3: “Flying Surfaces”
C.4 Stage 4: Other Items
C.5 Stage 5: Detail Definition
Bibliography
Index
End User License Agreement
List of Illustrations
Chapter 1: Preliminaries
Figure 1.1 The University of Southampton UAV team with eight of our
aircraft, March 2015.
Figure 1.2 The design spiral.
Chapter 2: Unmanned Air Vehicles
Figure 2.1 The Southampton University SPOTTER aircraft at the 2016
Farnborough International Airshow.
Figure 2.2 University of Southampton SPOTTER UAV with under-slung
payload pod.
Figure 2.3 Integral fuel tank with trailing edge flap and main spars.
Figure 2.4 A typical carbon spar and foam wing with SLS nylon ribs at
key locations (note the separate aileron and flap with associated servo
linkages).
Figure 2.5 A typical SLS structural component.
Figure 2.6 A typical integral fuel tank.
Figure 2.7 Typical telemetry data recorded by an autopilot.
Figure 2.8 Flight tracks of the SPOTTER aircraft while carrying out
automated takeoff and landing tests. A total of 23 fully automated flights
totaling 55 km of flying is shown.
Figure 2.9 A typical UAV wiring diagram.
Figure 2.10 The SkyCircuits SC2 autopilot (removed from its case).
Figure 2.11 University of Southampton SPOTTER UAV with under-
slung maritime flight releasable AUV.
Chapter 3: Wings
Figure 3.1 Variation of airfoil section drag at zero lift with section
Reynolds number and thickness-to-chord ratio.
Figure 3.2 A UAV with significant FDM ABS winglets (this aircraft also
has Custer ducted fans).
Figure 3.3 Wing foam core prior to covering or rib insertion – note
strengthened section in way of main wing spar.
Figure 3.4 Covered wing with spar and rib – in this case, the rib just acts
to transfer the wing twisting moment while the spar is bonded directly to
the foam without additional strengthening.
Figure 3.5 A SPOTTER UAV wing spar under static sandbag test.
Figure 3.6 SLS nylon wing rib with spar hole – note the extended load
transfer elements that are bonded to the main foam parts of the wing and
also flap hinge point.
Figure 3.7 Two wing foam cores with end rib and spar inserted – note in
this case the rib does not extend to the rear of the section, as a separate
wing morphing mechanism will be fitted to the rear of the wing.
Figure 3.8 SPOTTER UAV wing under construction showing the two-
part aileron plus flap, all hinged off a common rear wing spar – note also
the nylon torque peg on the rib nearest the camera.
Figure 3.9 UAV that uses wing warping for roll control.
Figure 3.10 UAV that uses tiperons for roll control.
Figure 3.11 Fowler flap – note the complex mechanism required to
deploy the flap.
Figure 3.12 Simple FDM-printed wing tip incorporated into the
outermost wing rib.
Figure 3.13 UAV with pneumatically retractable undercarriage – the main
wheels retract into the wings while the nose wheel tucks up under the
fuselage (wing cut-out shown prior to undercarriage installation).
Figure 3.14 Integral fuel tank in central wing section for SPOTTER UAV.
Chapter 4: Fuselages and Tails (Empennage)
Figure 4.1 SPOTTER SLS nylon engine nacelle/fuselage and interior
structure.
Figure 4.2 Bayonet system for access to internal avionics (a) and
fuselage-mounted switch and voltage indicators (b).
Figure 4.3 Load spreader plate on Mylar-clad foam core aileron.
Figure 4.4 Commercially produced model aircraft with foam fuselage
(and wings).
Figure 4.5 Space frame structure made of CFRP tubes with SLS nylon
joints and foam cladding.
Figure 4.6 DECODE aircraft with modular fuselage elements.
Figure 4.7 Wing attachment on SPOTTER fuselage. Note the recess for
square torque peg with locking pin between main and rear spar holes.
Figure 4.8 Typical engine and motor mounts for SLS nylon fuselages and
nacelles. Note the steel engine bearer in first view, engine hours meter in
second image, and vibration isolation in third setup.
Figure 4.9 Frustratingly small fuselage access hatch.
Figure 4.10 Typical plywood avionics boards with equipment mounted.
Note dual layer system with antivibration mounts in last image.
Figure 4.11 SULSA forward-looking video camera.
Figure 4.12 SPOTTER payload pods with fixed aperture for video
camera (a) and downward and sideways cameras (b and c).
Figure 4.13 Simple two axis gimbal system and Hero2 video camera
mounted in front of nose wheel.
Figure 4.14 Three-axis gimbal system and Sony video camera mounted
in front of the nose wheel. Note the video receiver system on the bench
that links to the camera via a dedicated radio channel.
Figure 4.15 SPOTTER integral fuel tank. Note internal baffle and very
small breather port (top left) in the close-up view of the filler neck.
Figure 4.16 Aircraft with SLS nylon fuselage formed in three parts: front
camera section attached by bayonet to rear two sections joined by tension
rods. Note the steel tension rod inside the hull just behind bayonet in the
right-hand image.
Figure 4.17 Example hatches in SLS nylon fuselages. Note the locking
pins and location tabs on the right-hand hatch.
Figure 4.18 Metal-reinforced nose wheel attachment with steering and
retract hinge in aluminum frame attached to SLS nylon fuselage. Note
the nose wheel leg sized to protect the antenna.
Figure 4.19 Nylon nose wheel attachment. Note the significant
reinforcement around the lower and upper strut bearings.
Figure 4.20 Tails attached directly to the fuselage. The right-hand aircraft
is a heavily modified commercial kit used for piggy-back launches of
gliders.
Figure 4.21 Tails attached using CFRP booms, both circular and square
in cross-section.
Figure 4.22 All-moving horizontal stabilizer with port/starboard split to
augment roll control and provide redundancy.
Figure 4.23 SLS nylon part to attach tail surfaces to a CFRP tail boom.
Chapter 5: Propulsion
Figure 5.1 UAV engine/electric motor/propeller test cell. Note the starter
generator on the engine behind the four-bladed propeller.
Figure 5.2 UAV engine dynamometer.
Figure 5.3 Typical maximum powers, weights, and estimated peak static
thrusts of engines for UAVs in the 2–150 kg MTOW range.
Figure 5.4 OS Gemini FT-160 glow-plug engine in pusher configuration.
Note the permanent wiring for glow-plugs.
Figure 5.5 OS 30 cc GF30 four-stroke engine installed in a hybrid
powered UAV. Note the significant size of the exhaust system.
Figure 5.6 Saito 57 cc twin four-stroke engine in pusher configuration.
Note the pancake starter generator fitted to this engine.
Figure 5.7 Twin 3W-28i CS single-cylinder two-stroke engines fitted to