A Wind Turbine Recipe Book (Jan 2009 English Units edition)

This is the latest edition of my 'axial flux windmill plans' as used in the courses I teach worldwide. The Recipe Book replaces my older plans 'How to Build a Wind Turbine' (2005).

The Recipe Book is a much better structured document than the older 2005 plans. Rather than evolving 'organically' it is carefully planned to include six different sizes of turbines. Each section offers general advice combined with specific dimensions and diagrams for each of these six sizes and a range of operating voltages.

During 2008 the Recipe book was only available in metric units, but in 2009 a new 'English Units' edition is also available (written specifically for North American readers who prefer to use Inches and AWG sizes for wire. It is based on the use of neodymium magnets sized 2" x 1" x 1/2" as available widely in North America.) Make sure you get the book that suits you best.


CONTENTS

1. Choosing what to do 4
A. Be safe! 4
B. How big? 4
C. Diagram of a small wind system 4
D. What can the wind turbine do? 4
a. Load controllers 5
b. Choosing battery voltage 5
c. Battery types 6
E. Why some popular ideas are not good ideas 6
a. Car alternators 6
b. Steel cores in the stator coils 7
c. Multiple rotors and stators 7
d. Vertical axis wind turbines (VAWTs) 7
e. Multi blade rotors 8
f. Rooftop mounting 8
g. Saving money off the electricity bill 8
h. Mounting a wind turbine on a car to charge the battery 8
i. Using a centrifugal clutch or brake to limit speed 9
j. Building a duct 9
F. What goes wrong with homebuilt wind turbines? 9
G. Useful web pages for more information: 9
2. Tools 10
A. Safety etc 10
B. All-purpose tools 10
C. For marking and measuring 10
D. Electrical 10
E. Resin preparation 10
F. Steelwork 10
G. Woodworking tools 10
3. Using the tools 11
A. Cordless drill 11
B. Screwdriver bits 11
C. Measurements 11
D. Vernier calipers 11
E. Levels 11
F. Compasses 11
G. Multimeters 12
H. Soldering technique 12
I. Electric Arc welding 12
J. Cutting steel 13
K. Drilling 13
L. Tapping a thread 13
M. Wood saws 13
N. Other wood cutting tools 14
O. Sandpaper 14
P. Power tools 14
4. Blades 15
A. Parts of the blade 15
B. Selecting the wood 15
C. The blank shapes 16
D. The trailing edge line 17
a. Mark out the shape of the blade at each of six stations along its length . 17
b. Carve away wood above the trailing edge line to create a new face 18
E. Blade thickness 18
F. Airfoil shape 19
G. Hub assembly 20
a. Cutting the 120 degree angles at the roots 20
b. The plywood pieces that sandwich the blades. 20
c. Marking out the holes in the plywood 20
H. Assembling the blades 21
I. Balancing 22
a. Balancing in situ 22
b. Fine balancing 22
c. Alternative ways to balance the blades 22
d. Balancing on a spike 23
e. Dynamic balance 23
J. Painting and finishing 23
5. Mechanics 24
A. The yaw bearing 24
B. The alternator 24
a. Choosing a hub 24
b. The magnet rotor disks 25
c. Alternator frame 26
d. Mounting the alternator to the yaw bearing 27
e. 3600 and 4200 turbines 29
C. The tail 30
a. The inclined hinge 30
b. Tail boom 31
c. Tail stops 32
Electrics 34
Energy conversion 34
Choosing wire size and number of turns per coil 34
Stator wiring connections 35
Three-phase stators 35
Battery charging with DC 36
The coils 36
12-volt stators marked * 36
Making the coil winder 37
Winding the coils 38
Connecting the coils 38
12-volt stators 39
The moulds 39
The stator mould 39
The 1200 stator mould 41
The magnet rotor mould 41
The magnet positioning jig 42
Resin casting 43
Casting the stator 43
Casting the magnet rotor(s) 45
Alternator assembly and testing 46
Rotor mounting options 46
Rotor mounting studs 47
Assembly 47
12-volt turbine rectifiers 48
Testing the alternator 48
Installation 49
Wiring the batteries 49
The rectifier and brake 49
Meters 50
Controller 50
Inverter 50
Commissioning the turbine 50
Guyed towers 51
Wiring the tower 51
Guyed tower pipe sizes 51
Guy anchors 52
Lifting the tower 53
Taller towers 53
Adjusting the guys 53
Alternator design 54
Matching the blades 54
Tip speed ratio (lambda l) 54
Calculating the blade rotor rpm 54
Blade power 54
Calculating the output voltage vs. speed 54
Wire sizes and power losses 55
Size of wire to use 55
Coil resistance 56
Stator resistance 56
Current and power loss 57
Rectifier loss 57
Efficiency 57
Windspeed 57
Stator cooling 57
Estimating the rpm 57
Blade speed at full power 58
Exploring some design factors 59
Magnet spacing 59
The effects of speed 59
The effects of system voltage on efficiency 59
Varying the voltage with the speed 59
High voltage transmission 59 Glossary 60
LIST OF USEFUL SUPPLIERS 62
MATERIALS REQUIRED FOR BUILDING THE WIND TURBINES 63