Reivindicaciones
CLAIMS I/We claim: 1. A wind turbine system, comprising: a wind turbine blade having a radially inner region and a radially outer region, wherein: the inner region includes a hub attachment element, an internal load- bearing truss structure extending longitudinally outwardly from the hub attachment element, and an external skin carried by the internal truss structure; and the outer region is positioned longitudinally outwardly from the internal truss structure, is attached to the internal truss structure, and has an internal load-bearing structure that does not include a load- bearing truss structure, the outer region further including a blade tip. 2. The system of claim 1 wherein the wind turbine blade has an overall length, and wherein the internal truss structure extends from the hub attachment element to a point approximately two-thirds of the overall length from the hub attachment element. 3. The system of claim 1 wherein the outer region includes a longitudinally extending spar, multiple ribs spaced along the spar, and a portion of the external skin is carried by the spar and the ribs. 4. The system of claim 1 wherein the truss structure of the inner region includes a plurality of longitudinally extending spars, multiple ribs spaced along the spars, and generally straight, slender truss members connected between the spars. 5. The system of claim 1 wherein the outer region has a monocoque structure. 6. The system of claim 1 wherein the outer region has a semi-monocoque structure. 7. The system of claim 1 wherein the truss structure of the inner region includes a first number of longitudinally extending spars, and wherein the outer region includes a second number of longitudinally extending spars, the second number being less than the first number. 8. The system of claim 1 wherein the truss structure of the inner region includes only three longitudinally extending spars, and wherein the outer region includes two longitudinally extending spars. 9. The system of claim 1 wherein the truss structure of the inner region includes a first longitudinally extending spar, and wherein the outer region includes a second longitudinally extending spar, and where the first and second spars extend along a generally smooth, continuous longitudinal axis. 10. The system of claim 1 wherein the inner region includes a first segment and a second segment positioned radially outwardly from the first segment, the first segment having a first spar segment, the second segment having a second spar segment joined to the first spar segment and positioned radially outwardly from the first spar segment. 11. A method for manufacturing a wind turbine blade, comprising: forming a radially inner region of a wind turbine blade to have a load-bearing truss structure; applying a skin to the truss structure; forming a radially outer region of the wind turbine blade to have a non-truss structure; and connecting the inner region of the wind turbine blade and the outer region of the wind turbine blade to each other. 12. The method of claim 11 wherein forming the radially outer region of the wind turbine blade includes forming the radially outer region of the wind turbine blade to have a monocoque structure. 13. The method of claim 11 wherein forming the radially outer region of the wind turbine blade includes forming the radially outer region of the wind turbine blade to have a semi-monocoque structure. 14. The method of claim 11 wherein forming the radially inner region of the wind turbine blade includes forming a first radially inner segment and a second radially inner segment, and wherein the method further comprises: connecting the first radially inner segment to the second radially inner segment at an installation site; connecting the radially outer region to the second radially inner segment at the installation site to form a radially extending wind turbine blade, with the second radially inner segment positioned between the first radially inner segment and the radially outward region; and mounting the wind turbine blade to a wind turbine hub at the installation site. 15. A method for operating a wind turbine, comprising: rotating a wind turbine shaft carrying multiple wind turbine blades; transmitting loads from an individual wind turbine blade to the shaft via a radially inner region of the blade and a radially outer region of the blade, the radially inner region including an internal load-bearing truss structure and an external skin carried by the internal truss structure, the radially outer region including a load-bearing skin position around a non-truss structure; and subjecting the individual wind turbine blade to cyclically varying gravitational loads by rotating the shaft about a generally horizontal axis. 16. The method of claim 15 wherein transmitting loads includes transmitting loads from the outer region of the blade to the shaft via the inner region of the blade. 17. The method of claim 15 wherein transmitting loads includes transmitting loads from the outer region of the blade across a spar joint to the inner region of the blade, and then to the shaft. 18. A wind turbine system, comprising: a wind turbine blade having a leading edge and a trailing edge, the wind turbine blade including a truss structure with: a longitudinally extending first spar positioned toward the leading edge; a longitudinally extending second spar positioned toward the leading edge and spaced apart from the first spar; a single, longitudinally extending third spar positioned toward the trailing edge; a plurality of spaced-apart ribs, with individual ribs connected to each of the first, second and third spars; a plurality of truss members connected among the first, second and third spars; and an external skin attached to and carried by the spars, the ribs, or both the spars and the ribs. 19. The system of claim 18 wherein the wind turbine blade includes an inner region having a generally circular hub attachment element, and an outer region positioned longitudinally outwardly from the inner region. 20. The system of claim 18 wherein the first, second and third spars are the only longitudinally extending spars of the wind turbine blade at a given longitudinal location along the truss structure. 21. The system of claim 18 wherein the wind turbine blade has an overall longitudinal length, and wherein the first, second and third spars are the only longitudinally extending spars of the wind turbine blade over a majority of the longitudinal length of the blade. 22. The system of claim 18 wherein the wind turbine blade has an overall longitudinal length, and wherein the first, second and third spars are the only longitudinally extending spars of the wind turbine blade over approximately two thirds of the longitudinal length of the blade. 23. The system of claim 18 wherein the first, second and third spars are the only longitudinally extending spars of the truss structure. 24. The system of claim 18 wherein an individual rib includes a first cut-out positioned to receive the first spar and a second cut-out positioned to receive the second spar. 25. The system of claim 18 wherein an individual rib has first web portion connected to the third spar and positioned forward of the third spar in a chordwise direction, and wherein the individual rib has a second web portion positioned aft of the third spar in the chordwise direction, the first and second web portions being discontinuous. 26. The system of claim 18 wherein the first spar has a rectangular cross- sectional shape with a chordwise dimension that is greater than its thickness dimension, and wherein the third spar has a rectangular cross-sectional shape with a chordwise dimension that is less than its thickness dimension. 27. The system of claim 18 wherein the first, second and third spars are each formed from a laminate of composite materials. 28. The system of claim 18 wherein a cross-section of the wind turbine blade has a chordwise dimension and a thickness dimension, and wherein the single third spar extends over a majority of the thickness dimension. 29. The system of claim 18 wherein the wind turbine blade is a first wind turbine blade, and wherein the system further comprises: a hub carrying the first wind turbine blade; a second wind turbine blade carried by the hub; and a third wind turbine blade carried by the hub, wherein each of the first, second and third wind turbine blades has only three longitudinally extending, load bearing spars at all portions of the blade having a truss structure. 30. A method for operating a wind turbine, comprising: rotating a wind turbine shaft carrying multiple wind turbine blades; and transmitting loads from an individual wind turbine blade to the shaft via an internal truss structure of the individual wind turbine blade that includes two longitudinally extending, load bearing spars toward a leading edge of the blade and a single longitudinally extending load bearing spar toward a trailing edge of the blade. 31. The method of claim 30 wherein rotating the shaft includes rotating the shaft about a generally horizontal axis, and wherein the method further comprises subjecting the individual wind turbine blade to cyclically varying gravitational loads as the shaft rotates. 32. The method of claim 30 wherein rotating the shaft includes rotating the shaft about a generally horizontal axis, and wherein the method further comprises subjecting the individual wind turbine blade to cyclically varying gravitational loads in a chordwise direction as the shaft rotates. 33. A method for manufacturing a wind turbine blade, comprising: forming a truss structure having only three longitudinally extending spars including a first spar toward a leading edge of the wind turbine blade, a second spar toward the leading edge of the wind turbine blade and a third spar positioned toward a trailing edge of the wind turbine blade; connecting truss members between the longitudinally extending spars; connecting ribs to the longitudinally extending spars; and connecting an external skin to the ribs, at least one of the spars, or both the ribs and at least one of the spars. 34. The method of claim 33 wherein connecting ribs to the longitudinally extending spars includes receiving the first spar in a first cutout of at least one of the ribs, and receiving the second spar in a second cutout of the at least one rib. 35. The method of claim 33 wherein connecting ribs to the longitudinally extending spars includes connecting a first portion of at least one rib to the third spar so as to extend in a forward chordwise direction, and positioning a second portion of the at least one rib aft of the third spar, the first and second portions being discontinuous from each other. 36. The method of claim 33 wherein forming the truss structure includes forming the truss structure with a single third spar that extends in a thickness direction over a majority of the thickness of the wind turbine blade. 37. A wind turbine system, comprising: a wind turbine blade including: a plurality of longitudinally extending spars; a plurality of longitudinally spaced-apart ribs, with individual ribs attached to the longitudinally extending spars; a plurality of truss attachment members, with individual truss attachment members connected to a spar, a rib, or both a spar and rib without the use of a hole in the respective spar, the rib or both the spar and the rib; and a plurality of truss members, with individual truss members connected between corresponding pairs of truss attachment members. 38. The system of claim 37 wherein: the spars are formed from a composite material, and wherein the truss attachment members include a spar attachment portion and a truss attachment portion, the spar attachment portion extending circumferentially around a spar and clamped to the spar, the truss attachment portion including a flange extending away from the spar and having a first attachment hole; and at least one of the truss members includes a second attachment hole; and wherein the system further comprises: a fastener extending through the first and second attachment holes but not into the spar. 39. The system of claim 38 wherein the truss member has a slot in which the flange of the truss attachment member is received. 40. The system of claim 37 wherein an individual truss attachment member is attached to a spar, and wherein the truss attachment member is formed from a metal and the spar is formed from a composite material. 41. The system of claim 37 wherein an individual truss attachment member is attached to a spar, and wherein both the truss attachment member and the spar are formed from a composite material. 42. The system of claim 41 wherein the spar and the truss attachment member are adhesively bonded. 43. The system of claim 41 wherein the spar and the truss attachment member are co-cured. 44. The system of claim 37 wherein the truss attachment member includes a first component extending circumferentially around a first portion of the spar, a second component extending circumferentially around a second portion of the spar, and at least one fastener connecting the first and second components and clamping the spar between the first and second components. 45. The system of claim 44 wherein the fastener is positioned to both clamp the spar between the first and second components and attach one of the truss members to the truss attachment member. 46. The system of claim 37 wherein: the spars are formed from a composite material, and wherein the truss attachment members include a first component extending circumferentially around a first portion of the spar and a second component extending circumferentially around a second, complementary portion of the spar, the first component having two first flanges, one extending outwardly from the spar in first direction, and the other extending outwardly from the spar in a second direction different than the first direction, the second component having two second flanges, one extending outwardly from the spar in the first direction and positioned surface-to-surface against one of the first flanges of the first component, and the other of the second flanges extending outwardly in the second direction and positioned surface-to-surface against the other first flange of the first component, each of the first flanges having a first fastener opening, each of the second flanges having a second fastener opening aligned with a corresponding one of the first fastener openings; a first truss member having a slot in which the first flanges are received; a second truss member having a slot in which the second flanges are received; a first fastener passing through the first truss member, one of the first fastener openings, and the corresponding aligned second fastener opening to secure the first truss member to the truss attachment member and clamp the first and second components around the spar; and a second fastener passing through the second truss member, the other of the first fastener openings, and the corresponding aligned second fastener opening to secure the second truss member to the truss attachment member and clamp the first and second components around the spar; wherein neither the first nor the second fasteners pass into the spar. 47. The system of claim 37 wherein at least one of the truss members is attached to one of the individual ribs and to one of the truss attachment members to provide an attachment between one of the spars and the individual rib. 48. The system of claim 47 wherein the rib has a web and a flange, and the truss attachment member is attached to the web of the rib. 49. The system of claim 37 wherein the truss attachment member is attached to one of the individual spars, and extends around only a portion of the spar. 50. The system of claim 37 wherein the truss attachment member is adhesively attached to one of the individual spars. 51. A method for making a wind turbine blade, comprising: positioning a plurality of ribs to be longitudinally spaced-apart from each other, the ribs including a first rib and a second rib; positioning first and second longitudinally extending spars proximate to the ribs; connecting a first truss attachment member to the first spar, the first rib, or both the first spar and the first rib without the use of a hole in the respective first spar, the first rib or both the first spar and the first rib; connecting a second truss attachment member to the second spar, the second rib, or both the second spar and the second rib without the use of a hole in the respective second spar, the second rib or both the second spar and the second rib; and connecting a truss member between the first and second truss attachment members. 52. The method of claim 51 wherein the first truss attachment member includes a first component and a second component and wherein connecting the first truss attachment member includes clamping the first and second components around the first spar. 53. The method of claim 51 wherein the truss member is a first truss member and wherein the first truss attachment member includes a first component and a second component, the first component having two first flanges, one extending outwardly from the spar in first direction, and the other extending outwardly from the spar in a second direction different than the first direction, the second component having a two second flanges, one extending outwardly from the spar in the first direction and the other of the second flanges extending outwardly from the spar in the second direction, and wherein connecting the first truss attachment member includes: positioning the first component to extend around a first circumferential portion of the first spar; positioning the second component to extend around a second circumferential portion of the first spar; placing one of the first flanges to face toward one of the second flanges to form a first flange pair; placing the other of the first flanges to face toward the other of the second flanges to form a second flange pair; receiving the first flange pair in a slot of the first truss member; receiving the second flange pair in a slot of a second truss member; both clamping the first and second components around the spar and attaching the first truss member to the first truss attachment member by passing a first fastener through the first truss member and the first flange pair; and both clamping the first and second components around the spar and attaching the second truss member to the first truss attachment member by passing a second fastener through the second truss member and the second flange pair. 54. The method of claim 51 wherein connecting the first truss attachment member includes connecting the first truss attachment member to the first spar, and wherein connecting the second truss attachment member includes connecting the second truss attachment member to the second spar, and wherein the method further comprises connecting the first rib to the truss member. 55. The method of claim 54 wherein connecting the first rib to the truss member includes connecting the first rib to the truss member with an adhesive. 56. The method of claim 54 wherein the first rib includes a web and a flange, and wherein connecting the first rib to the truss member includes connecting the web of the first rib to the truss member. 57. The method of claim 51 wherein connecting the first truss attachment member includes adhesively bonding the first truss attachment member to the first spar. 58. The method of claim 51 wherein the first truss attachment member and the first spar are formed from composite materials, and wherein connecting the first truss attachment member includes co-curing the first truss attachment member and the first spar. 59. A wind turbine system, comprising: a wind turbine blade including: a generally arcuate hub attachment element; an external aerodynamic surface having a longitudinal axis, a chordwise axis transverse to the longitudinal axis, and a thickness axis transverse to both the chordwise and longitudinal axes; and a spar extending along the longitudinal axis, the spar including a plurality of layers stacked relative to each other at a location spaced apart from the hub attachment element, wherein the plurality of layers transition from a rectangular cross-sectional shape to an arcuate cross-sectional shape at the hub attachment element. 60. The system of claim 59 wherein the layers include a first number of layers having generally unidirectional fibers aligned with the longitudinal axis at a first location positioned a first distance from the hub attachment element, and second number of layers having unidirectional fibers aligned with the longitudinal axis at a second location positioned a second distance from the hub attachment portion, the second distance being less than the first distance, the second number being less than the first number. 61. The system of claim 60, further comprising a third number of layers oriented at a non-zero, positive value relative to the longitudinal axis at the second location, and a fourth number of layers oriented at a non-zero negative value relative to the spanwise axis at the second location. 62. The system of claim 61 wherein the third number is different than the second number. 63. The system of claim 59 wherein the spar is one of three spars, each having stacked layers that transition from a rectangular cross-sectional shape to an arcuate cross-sectional shape at the hub attachment element. 64. The system of claim 59 wherein the hub attachment element includes a ring. 65. The system of claim 64 wherein the ring includes a bolt holes positioned to attach the wind turbine blade to a hub. 66. The system of claim 59 wherein the spar is a first spar and forms a portion of a truss structure, the truss structure further including a second spar, a third spar, a plurality of ribs positioned transverse to the spars, and a plurality of truss members connected between the spars and the ribs. 67. A wind turbine system, comprising: a wind turbine blade including: an external aerodynamic surface having a longitudinal axis, a chordwise axis transverse to the longitudinal axis, and a thickness axis transverse to both the chordwise and longitudinal axes; a spar extending along the longitudinal axis, the spar including a plurality of layers stacked relative to each other; a generally arcuate hub attachment element; and a transition element attached to the hub attachment element and to the layers of the spar, the transition element having recesses in which the layers are received, at least part of the transition element having an arcuate cross-sectional shape. 68. The system of claim 67 wherein the hub attachment element includes a generally circular ring, and wherein the transition element is attached to the generally circular ring. 69. The system of claim 68 wherein the transition element includes a transition plate having a generally rectilinear cross-sectional shape at an interface with the layer, and a generally arcuate shape at an interface with the generally circular ring. 70. The system of claim 67 wherein the transition element is one of two transition plates, each having recesses in which layers of the spar are received, with a first one of the transition plates receiving first layers and a second one of the transition plates receiving second layers different than the first, the first transition plate being positioned radially inwardly from the second transition plate. 71. The system of claim 67 wherein the spar is one of multiple spars extending along the longitudinal axis, with each spar including a plurality of layers stacked relative to each other, and wherein the transition element is one of a plurality of transition plates, each having recesses in which the layers of a corresponding one of the spars are received. 72. The system of claim 67 wherein the layers are composite layers. 73. The system of claim 67 wherein the spar is a first spar and forms a portion of a truss structure, the truss structure further including a second spar, a third spar, a plurality of ribs positioned transverse to the spars, and a plurality of truss members connected between the spars and the ribs. 74. A method for manufacturing a wind turbine blade, comprising: positioning a spar to extend in a longitudinal direction, the spar including a plurality of stacked layers and having a generally rectangular cross- sectional shape; positioning an arcuate hub attachment element proximate to the spar; mechanically attaching the spar to the hub attachment element via a transition portion that transitions between the generally rectangular cross-sectional shape at the spar and an arcuate shape at the hub attachment element. 75. The method of claim 74 wherein mechanically attaching includes shaping individual layers of the spar to have an increased circumferential extent and an increasingly arcuate shape as the individual layers extend toward the hub attachment element. 76. The method of claim 75 further comprising selecting first individual layers of the spar to have an increased circumferential extent and an increasingly arcuate shape as the first individual layers extend toward the hub attachment element, and selecting second individual layers to terminate at a location spaced apart from the hub attachment element. 77. The method of claim 75 further comprising: selecting first individual layers of the spar to have an increased circumferential extent and an increasingly arcuate shape as the first individual layers extend toward the hub attachment element; selecting second individual layers to terminate at a location spaced apart from the hub attachment element; and adding third layers in place of at least some of the second layers, wherein the first layers have fibers with a first directional orientation, the second layers have fibers with a second directional orientation, and the third layers have fibers with a third directional orientation different than the second directional orientation. 78. The method of claim 77, further comprising orienting fibers of the second layers to be generally parallel to the longitudinal direction, and orienting fibers of the third layers non-parallel to the longitudinal direction. 79. The method of claim 74 wherein mechanically attaching the spar to the hub attachment element includes: positioning a transition element between the spar and the hub attachment element; receiving layers of the spar in corresponding recesses of the transition element; attaching the received layers to the transition element; and attaching an arcuate portion of the transition element to the hub attachment element. 80. The method of claim 79 wherein the transition element is a first transition element, and wherein receiving layers includes receiving first layers, and wherein the method further comprises: positioning a second transition element between the spar and the hub attachment element; receiving second layers of the spar in corresponding recesses of the second transition element; attaching the received layers to the second transition element; and attaching an arcuate portion of the second transition element to the hub attachment element, with the second transition element being positioned radially outwardly from the first transition element. 81. The method of claim 79 wherein the transition element is a first transition element, and the spar is a first spar, and wherein the method further comprises: positioning a second spar to extend generally in the longitudinal direction, the second spar including a plurality of stacked layers and having a generally rectangular cross-sectional shape; positioning a second transition element between the second spar and the hub attachment element; receiving layers of the second spar in corresponding recesses of the second transition element; attaching the received layers to the second transition element; and attaching an arcuate portion of the second transition element to the hub attachment element at a different circumferential location than where the first transition element is attached to the hub attachment element. 82. The method of claim 74 wherein the transition element includes a plate that tapers from an arcuate cross-sectional shape at the hub attachment element to a generally rectilinear cross-sectional shape at an interface with the spar. 83. The method of claim 74 wherein the spar is a first spar, and wherein the method further comprises: positioning a second spar to be spaced apart from the first spar; positioning a third spar to be spaced apart from the first and second spars positioning a plurality of ribs transverse to the spars; and connecting a plurality of truss members between the spars and the ribs. 84. A wind turbine blade, comprising: an external aerodynamic surface having a longitudinally-extending spanwise axis, a chordwise axis extending transverse to the spanwise axis, and a thickness axis extending transverse to both the chordwise and spanwise axes; and a plurality of longitudinally-extending spars providing internal support for the aerodynamic surface, wherein at least one of the spars includes a laminate of precured composite material, the laminate of precured composite material including: a plurality of precured composite layers; and a plurality of adhesive layers interposed between adjacent precured composite layers. 85. The wind turbine blade of claim 84 wherein each of the precured composite layers includes a precured fiber-reinforced resin product. 86. The wind turbine blade of claim 84 wherein each of the precured composite layers includes a precured composite pultrusion. 87. The wind turbine blade of claim 84 wherein the aerodynamic surface defines an airfoil cross-section, wherein the plurality of longitudinally-extending spars include a pressure spar and a suction spar spaced apart from each other along the thickness axis, and an aft spar spaced apart from both the pressure and suction spars along the chordwise axis, and wherein each of the pressure, suction and aft spars are comprised of a laminate of precured composite pultrusions. 88. The wind turbine blade of claim 84, further comprising a plurality of longitudinally spaced-apart ribs, and wherein the at least one spar is attached to the ribs. 89. The wind turbine blade of claim 84, further comprising a strap clamped circumferentially around the plurality of precured composite layers. 90. The wind turbine blade of claim 84, further comprising: a plurality of longitudinally spaced-apart ribs; and a plurality of truss attachment members, wherein each of the truss attachment members includes a first piece and a corresponding second piece, wherein each of the first pieces is attached to the corresponding second piece to clamp a portion of the precured composite layers together therebetween, and wherein at least one of the first piece and the second piece of each truss attachment member is attached to one of the longitudinally spaced apart ribs. 91. A wind turbine blade comprising: an external aerodynamic surface having a longitudinally-extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes; and a plurality of longitudinally-extending spars, wherein at least one of the spars includes: a longitudinally extending first spar portion having a plurality of laminated first layers, wherein individual first layers terminate at different longitudinal locations to form a first end portion having a plurality of first projections and first recesses, with individual first projections alternating with individual first recesses along the thickness axis; a longitudinally extending second spar portion having a plurality of laminated second layers, wherein individual second layers terminate at different longitudinal locations to form a plurality of second projections and second recesses, with individual second projections alternating with individual second recesses along the thickness axis; and wherein individual second projections are received in corresponding first recesses, and individual first projections are received in corresponding second recesses, to join the first spar portion to the second spar portion. 92. The wind turbine blade of claim 91 wherein the individual second projections are bonded to the corresponding first recesses, and the individual first projections are bonded to the corresponding second recesses, to join the first spar portion to the second spar portion along a bondline having a location that varies in a non-monotonic manner. 93. The wind turbine blade of claim 91 wherein the individual second projections are bonded to the corresponding first recesses, and the individual first projections are bonded to the corresponding second recesses, to join the first spar portion to the second spar portion along a bondline having a zig-zag shape. 94. The wind turbine blade of claim 91 wherein the plurality of laminated first layers includes a plurality of first precured composite layers, and wherein the plurality of laminated second layers includes a plurality of second precured composite layers 95. The wind turbine blade of claim 91 , further comprising a plurality of longitudinally spaced-apart ribs, and wherein the at least one spar is attached to the ribs. 96. The wind turbine blade of claim 91 , further comprising a web, and wherein the at least one spar is attached to the web. 97. The wind turbine blade of claim 91 , further comprising: a first strap clamped circumferentially around the first layers; and a second strap clamped circumferentially around the second layers. 98. The wind turbine blade of claim 91 , further comprising: a plurality of longitudinally spaced-apart ribs; and a first truss attachment member, wherein the first truss attachment member includes a first piece and a corresponding second piece, wherein the first piece is attached to the second piece to clamp the individual first layers of the first spar portion therebetween, and wherein at least one of the first piece and the second piece of the first truss attachment member is attached to a first one of the longitudinally spaced apart ribs; and a second truss attachment member, wherein the second truss attachment member includes a third piece and a corresponding fourth piece, wherein the third piece is attached to the fourth piece to clamp the individual second layers of the second spar portion therebetween, and wherein at least one of the third piece and the fourth piece of the second truss attachment member is attached to a second one of the longitudinally spaced apart ribs. 99. A wind turbine blade comprising: an external aerodynamic surface having a longitudinally-extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes; and a longitudinally extending first spar portion having a plurality of laminated first layers that form a first spar end portion with a plurality of first projections and first recesses along the chordwise axis; a longitudinally extending second spar portion having a plurality of second laminated layers that form a second spar end portion having plurality of second projections and second recesses along the chordwise axis; and wherein individual second projections are received in corresponding first recesses, and individual first projections are received in corresponding second recesses, to join the first spar end portion to the second spar end portion. 100. The wind turbine blade of claim 99 wherein all the first layers terminate in first end portions and all the second layers terminate in second end portions, and wherein all the first end portions have a first shape and all the second end portions have a second shape. 101. The wind turbine blade of claim 99 wherein all the first layers terminate in first end portions and all the second layers terminate in second end portions, wherein individual first end portions have corresponding individual first shapes that define the corresponding first projections and the first recesses along the chordwise axis, and wherein individual second end portions have individual second shapes that define the corresponding second projections and the second recesses along the chordwise axis. 102. The wind turbine blade of claim 99 wherein all of the first layers terminate in first end portions having a first zig-zag shape along the chordwise axis, and wherein all of the second layers terminate in second end portions having a second zig-zag shape along the chordwise axis that compliments the first zig-zag shape. 103. An apparatus for compressing a plurality of precured composite material layers together for lamination, the apparatus comprising a first tool portion including: a first support base; a first expandable member carried by the first support base; and a first fitting in fluid communication with the first expandable member; and a second tool portion including: a second support base; a second expandable member carried by the second support base; and a second fitting in fluid communication with the second expandable member, wherein the second support base is configured to be operably coupled to the first support base with the plurality of composite material layers positioned between the first and second expandable members, and wherein the first and second fittings are configured to transfer fluid into the first and second expandable members to expand the expandable members and compress the composite material layers therebetween. 104. The apparatus of claim 103 wherein the first and second tool portions are configured to be fit together in a clamshell arrangement around the composite material layers. 105. The apparatus of claim 103 wherein the first tool portion includes first and second side flanges extending outwardly from opposite sides of the first support base, wherein the second tool portion includes third and forth side flanges extending outwardly from opposite sides of the second support base, and wherein the first side flange is configured to overlap the third side flange, and the second side flange is configured to overlap the fourth side flange, when the first tool portion is operably coupled to the second tool portion with the plurality of composite material layers positioned therebetween. 106. The apparatus of claim 103: wherein the first tool portion further comprises: at least a third expandable member positioned adjacent to the first expandable member; and a first manifold extending from the fitting to the first and third expandable members; and wherein the second tool portion further comprises: at least a fourth expandable member positioned adjacent to the second expandable member; and a second manifold extending from the fitting to the second and fourth expandable members, wherein the first fitting is configured to transfer fluid into the first and third expandable members via the first manifold to expand the first and third expandable members against one side of the composite material layers, and wherein the second fitting is configured to transfer fluid into the second and fourth expandable members via the second manifold to expand the second and fourth expandable members against the opposite side of the composite material layers to compress the composite material layers therebetween. 107. A method of manufacturing a wind turbine blade, the method comprising: moving fibers through a resin bath to wet the fibers with resin; moving the wet fibers through a heated die to cure the resin and shape the resin and fibers into an elongate composite pultrusion; cutting the elongate composite pultrusion into individual pieces to form a plurality of pultruded composite pieces; laminating the plurality of pultruded composite pieces together to form a first wind turbine blade structure; and attaching the first wind turbine blade structure to a second wind turbine blade structure to form a portion of a wind turbine blade truss structure. 108. The method of claim 107 wherein laminating the plurality of pultruded composite pieces together to form a first wind turbine blade structure includes forming an elongate spar. 109. The method of claim 107 wherein the wind turbine blade includes an external aerodynamic surface having a longitudinally-extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes, wherein laminating the plurality of pultruded composite pieces together to form a first wind turbine blade structure includes forming a spar portion, and wherein attaching the first wind turbine blade structure to a second wind turbine blade structure includes orienting the spar portion along the spanwise axis and fixedly attaching the spar portion to a plurality of ribs extending along the chordwise axis. 110. The method of claim 107: wherein the wind turbine blade includes an external aerodynamic surface having a longitudinally-extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes; wherein laminating the plurality of pultruded composite pieces together to form a first wind turbine blade structure includes laminating a first plurality of pultruded composite layers together to form a first spar portion having a first spar end portion with a plurality of first projections and first recesses along the chordwise axis, and laminating a second plurality of pultruded composite layers together to form a second spar portion having a second spar end portion with a plurality of second projections and second recesses along the chordwise axis; and wherein attaching the first wind turbine blade structure to a second wind turbine blade structure includes inserting individual first projections into corresponding second recesses, and inserting individual second projections into corresponding first recesses, to join the first spar end portion to the second spar end portion. 111. A method of manufacturing a wind turbine blade having an external aerodynamic surface with a longitudinally-extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes, the method comprising: positioning a plurality of turbine blade ribs in a manufacturing assembly, wherein individual ribs are aligned with the chordwise axis and are spaced apart from each other along the spanwise axis; positioning a first elongate layer of composite material across the plurality of ribs along the spanwise axis; applying a layer of adhesive to the first layer of composite material; positioning a second elongate layer of composite material on the layer of adhesive; compressing the first and second elongate layers of composite material together; and curing the adhesive to laminate the second layer of composite material to the first layer of composite material and form a spar portion extending along the spanwise axis between the plurality of ribs. 112. The method of claim 111 wherein positioning a first elongate layer of composite material across the plurality of ribs includes positioning a first layer of precured composite material across the ribs, and wherein positioning a second elongate layer of composite material on the layer of adhesive includes positioning a second layer of precured composite material on the layer of adhesive. 113. The method of claim 111 wherein positioning a first elongate layer of composite material across the plurality of ribs includes positioning a first pultruded layer across the ribs, and wherein positioning a second elongate layer of composite material on the layer of adhesive includes positioning a second pultruded layer on the layer of adhesive. 114. The method of claim 111 wherein each of the individual ribs includes a cutout, and wherein positioning a first elongate layer of composite material across the plurality of ribs includes positioning portions of the first elongate layer of composite material into each of the cutouts. 115. The method of claim 111 wherein each of the individual ribs includes a cutout, and wherein the method further comprises: positioning individual fittings in each of the individual cutouts; attaching the individual fittings to the corresponding ribs; and attaching a corresponding portion of the spar portion to each of the individual fittings. 116. The method of claim 111 , further comprising: positioning a plurality of additional elongate layers of composite material on the first and second elongate layers; and terminating the individual layers of composite material at different longitudinal locations to form a spar end portion having a plurality of projections and recesses, with individual projections alternating with individual recesses along the thickness axis. 117. The method of claim 111 wherein curing the adhesive to laminate the second layer of composite material to the first layer of composite material and form a spar portion includes forming a spar end portion having a plurality of projections and recesses, with individual projections alternating with individual recesses along the chordwise axis. 118. The method of claim 111 wherein the plurality of turbine blade ribs is a plurality of first turbine blade ribs, wherein curing the adhesive to laminate the second layer of composite material to the first layer of composite material and form a spar portion includes forming a first spar portion having a first spar end portion with a plurality of first projections and first recesses, and wherein the method further comprises: positioning a plurality of second turbine blade ribs in a second manufacturing assembly, wherein individual second ribs are aligned with the chordwise axis and are spaced apart from each other along the spanwise axis; positioning a third elongate layer of composite material across the plurality of second ribs along the spanwise axis; applying a second layer of adhesive to the third layer of composite material; positioning a fourth elongate layer of composite material on the second layer of adhesive; compressing the third and fourth elongate layers of composite material together; curing the second layer of adhesive to laminate the third layer of composite material to the fourth layer of composite material and form a second spar portion extending along the spanwise axis between the plurality of second ribs, the second spar portion including a second spar end having a plurality of second projections and second recesses; applying adhesive to the first spar end portion and the second spar end portion; inserting individual first projections into corresponding individual second recesses, and inserting individual second projections into corresponding first recesses, to join the first spar portion to the second spar portion. 119. The method of claim 111 wherein compressing the first and second elongate layers of composite material together includes: removably coupling a plurality of compressing apparatuses to the first and second layers of composite material between individual turbine blade ribs; and operating the compressing apparatuses to compress the first and second layers of composite material together. 120. The method of claim 111 wherein compressing the first and second elongate layers of composite material together includes: positioning a first tool portion on one side of the first and second layers of composite material, the first tool portion having an expandable member; positioning a second tool portion on the opposite side of the first and second layers of composite material; coupling the first tool portion to the second tool portion; and expanding the expandable member to compress the first and second layers of composite material together. 121. The method of claim 111 wherein compressing the first and second elongate layers of composite material together includes: positioning a first tool portion on one side of the first and second layers of composite material, the first tool portion having an expandable member; positioning a second tool portion on the opposite side of the first and second layers of composite material; coupling the first tool portion to the second tool portion; and inflating the expandable member to compress the first and second layers of composite material together. 122. The method of claim 111 wherein compressing the first and second elongate layers of composite material together includes: positioning a first tool portion on one side of the first and second layers of composite material, the first tool portion having a first expandable member; positioning a second tool portion on the opposite side of the first and second layers of composite material, the second tool portion having a second expandable member; coupling the first tool portion to the second tool portion; and expanding the first and second expandable members to compress the first and second layers of composite material together. 123. A method for making a wind turbine blade having a longitudinally extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes, the method comprising: laminating a plurality of first material layers together to form a longitudinally- extending first spar portion, wherein individual first material layers terminate at different longitudinal locations to form a plurality of first projections and first recesses, with individual first projections interleaved with individual first recesses along the thickness axis; laminating a plurality of second material layers together to form a longitudinally- extending second spar portion, wherein individual second material layers terminate at different longitudinal locations to form a plurality of second projections and second recesses, with individual second projections interleaved with individual second recesses along the thickness axis; engaging the first projections of the first spar portion with corresponding second recesses of the second spar portion and engaging the second projections of the second spar portion with corresponding first recesses of the first spar portion; and fixing the first projections in the second recesses and fixing the second projections in the first recesses. 124. The method of claim 123 wherein laminating a plurality of first material layers together includes laminating a plurality of first composite material layers together, and wherein laminating a plurality of second material layers together includes laminating a plurality of second composite materials together. 125. The method of claim 123 wherein laminating a plurality of first material layers together includes laminating a plurality of first precured composite material layers together, and wherein laminating a plurality of second material layers together includes laminating a plurality of second precured composite materials together. 126. The method of claim 123 wherein laminating a plurality of first material layers together includes laminating a plurality of first pultruded composite layers together, and wherein laminating a plurality of second material layers together includes laminating a plurality of second pultruded composite materials together. 127. A method for making a wind turbine blade having a longitudinally extending spanwise axis, a chordwise axis transverse to the spanwise axis, and a thickness axis transverse to both the chordwise and spanwise axes, the method comprising: laminating a plurality of first composite material layers together to form a longitudinally-extending first spar portion, wherein the first spar portion includes a first spar end portion having a plurality of first projections and first recesses; laminating a plurality of second composite material layers together to form a longitudinally-extending second spar portion, wherein the second spar portion includes a second spar end portion having a plurality of second projections and second recesses; engaging the first projections of the first spar portion with corresponding second recesses of the second spar portion and engaging the second projections of the second spar portion with corresponding first recesses of the first spar portion; and bonding the first projections in the second recesses and bonding the second projections in the first recesses. 128. The method of claim 127, wherein laminating a plurality of first composite material layers together includes laminating a plurality of first precured composite material layers together, and wherein laminating a plurality of second composite material layers together includes laminating a plurality of second precured composite material layers together. 129. The method of claim 127, wherein laminating a plurality of first composite material layers together includes laminating a plurality of first pultruded layers together, and wherein laminating a plurality of second composite material layers together includes laminating a plurality of second pultruded layers together. 130. The method of claim 127 wherein laminating a plurality of first composite material layers together includes forming a first spar end portion having individual first projections interleaved with individual first recesses along the chordwise axis, and wherein laminating a plurality of second composite material layers together includes forming a second spar end portion having individual second projections interleaved with individual second recesses along the chordwise axis.
