Patent Publication Number: US-2011052400-A1

Title: Horizontal axis wind turbine (HAWT)

Description:
TECHNICAL FIELD 
     The invention generally pertains to the field of wind turbines and more particularly to a to horizontal axis wind turbine (HAWT). 
     BACKGROUND ART 
     A study of contemporary windmill blades indicates that the design of most blades is based on aircraft wings having a twist. The cross-sectional designs of the windmill blades closely resemble that of aircraft wings, with some blades simply reversed in one plane, thereby resulting in a greater camber on the lower surface of the airfoil profile rather than on the upper surface as with aircraft wings and propellers. Furthermore, windmill blades typically have a very high aspect ratio and taper to the tip, a combination that leads to significantly reduced wind capture. Typically, blade diameters of 15 to 20 feet (4.6 to 6.1 meters) are required to power an average home, thus making it difficult to install a windmill in residential areas, particularly due to strict city ordinances that limit the maximum wind turbine diameter within home installations. For example, in the UK the limit is one meter in diameter within urban areas of the country. 
     Another common denominator of contemporary blades is that they utilize Bernoulli&#39;s principle only. Consequently, with at least a century of development, the state of art has more or less reached a peak in efficiency, as measured by the power coefficient. An increase of only a minimal percentage of the existing efficiency is now considered significant. 
     A search of the prior art did not disclose any literature or patents that read directly on the claims of the instant invention however, the following U.S. patents are considered related: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 PATENT NO. 
                 INVENTOR 
                 ISSUED 
               
               
                   
                   
               
             
            
               
                   
                 6,116,856 
                 Karadgy et al 
                 12 Sep. 2000 
               
               
                   
                 6,068,446 
                 Tangler et al 
                 30 May 2000 
               
               
                   
                 5,562,420 
                 Tangler et al 
                 8 Oct. 1996 
               
               
                   
                 5,474,425 
                 Lawlor 
                 12 Dec. 1995 
               
               
                   
                 5,417,548 
                 Tangler et al 
                 23 May 1995 
               
               
                   
                 2,269,287 
                 Roberts 
                 6 Jan. 1942 
               
               
                   
                 2,101,535 
                 Engdahl 
                 7 Dec. 1937 
               
               
                   
                 1,995,193 
                 Stilphen 
                 19 Mar. 1935 
               
               
                   
                   
               
            
           
         
       
     
     U.S. Pat. No. 6,116,856 issued to Karadgy et al discloses a bi-directional, asymmetrical fan blade having a twist. The airfoil profiles of these blades are ‘S’ shaped and are typically utilized for low Reynolds number operation. 
     U.S. Pat. Nos. 6,068,446, 5,562,420 and 5,417,548 issued to Tangier et al address the roughness problem associated with wind blades. The solution to this problem is by the use of three current families of airfoil profiles, none of which resemble those of the instant application. 
     U.S. Pat. No. 5,474,425 issued to Lawlor discloses a wind turbine rotor blade having a horizontal axis that is self-regulating. The blade is designed by employing defined NREL inboard, midspan and outboard airfoil profiles. The profiles interpolate between the defined profiles and from the latter to the root and the tip of the blades. This patent addresses self-regulating, stall-regulated blades and leading edge soiling, and the blade utilizes different families of contemporary profiles. The patent does not address the blade&#39;s wind capture or low wind velocity operation. 
     U.S. Pat. No. 2,269,287 issued to Roberts discloses fan blade profiles having a sharp leading edge and a blunt trailing edge. The blunt trailing edge would create significant drag when rotating at high speeds. This blade&#39;s cross-sectional profiles are therefore unsuitable for use in current windmills and substantially differ from those of the instant invention, which utilizes a pointed leading and trailing edge and has several other critical differences. 
     U.S. Pat. No. 2,101,535 issued to Engdahl discloses a reversible fan propeller with an aircraft wing profile. The blades of the propeller alternate with one blade having a sharp trailing edge followed by a blade with a sharp leading edge. One end of each of these profiles is rounded. A rounded trailing edge on a high velocity blade will create substantial drag. These profiles, when compared to the profiles of the instant invention, including the planform, are significantly different. 
     U.S. Pat. No. 1,995,193 issued to Stilphen discloses a propeller type fan blade without a twist, which utilizes ‘S’ shaped profiles with a leading edge that is tipped downwards. This profile has considerably different aerodynamic characteristics than those disclosed in the instant application. Airfoils are extremely sensitive to any slight changes in profile, particularly as the profile rises up into higher Reynolds numbers, as required of windmill blades. Fans operate at very low Reynolds numbers. Upon inspection, comparisons of the ‘S’ shaped profiles differ from those disclosed in the instant invention. 
     Essentially, none of the above-cited patents taken either alone or in combination disclose the novelties of the instant invention in dealing with the problems discussed above. Additionally, none of the patents address the problem of wind capture by the blades or tip drag. 
     For background purposes and as indicative of the art to which the invention relates, reference may be made to the following remaining patents found in the search: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 PATENT NO. 
                 INVENTOR 
                 ISSUED 
               
               
                   
                   
               
             
            
               
                   
                 6,800,956 
                 Bartlett 
                 5 Oct. 2004 
               
               
                   
                 6,752,595 
                 Murakami 
                 22 Jun. 2004 
               
               
                   
                 6,582,196 
                 Andersen et al 
                 24 Jun. 2003 
               
               
                   
                 6,302,652 
                 Roberts 
                 16 Oct. 2001 
               
               
                   
                 6,132,181 
                 McCabe 
                 17 Oct. 2000 
               
               
                   
                 5,161,953 
                 Burtis 
                 10 Nov. 1992 
               
               
                   
                 4,976,587 
                 Johnston et al 
                 11 Dec. 1990 
               
               
                   
                 4,969,800 
                 Parry et al 
                 13 Nov. 1990 
               
               
                   
                 4,698,011 
                 Lamalle et al 
                 6 Oct. 1987 
               
               
                   
                 4,408,958 
                 Schacle 
                 12 Oct. 1983 
               
               
                   
                   
               
            
           
         
       
     
     DISCLOSURE OF THE INVENTION 
     The data presented for the instant invention is empirically based. Formulas are derived and presented for prediction of data, thus providing the range of data presented herein. 
     The instant invention is comprised of a HAWT, which consists of at least two blades designed to operate against low to medium wind velocities ranging from 5 mph to 35 mph (2.2 m/s to 15.65 m/s) and with blade diameter of at least 3 feet (0.91 meters). 
     The blade diameter is related to the range of other parameters provided, thus giving a broad scope within the spirit of the instant invention. 
     The invention discloses a stall-regulated turbine that does not require costly pitching devices. The blade also features a design that provides improved wind capture and therefore can operate at low wind speeds with high performance. 
     As derived from the Power Table below, the power contained in the wind with respect to the circular surface area, taken from the center of the circular surface area as in the case of wind turbines, is not linear but proportional to the square of the radius that is due to a circle&#39;s geometry and the fact that power in this case is proportional to the area involved. For example, at 50% of the radius of the rotor, only 25% of the full power in the wind is available and 50% of the power is contained within the last 29.29% of the rotor diameter. This aspect of geometry is efficiently utilized in the instant invention to produce an improved turbine that has greater efficiency and is viable in low and high wind velocities. 
     The Power Table utilizes the following formula: 
       %  P= 100 r   x   2  or  r   x =√(%  P/ 100)
 
     where % P=the percentage of wind power at a given velocity incident upon a windmill rotor of radius r=1 (unity) and where r x  denotes a longitudinal location on the blade. 
     
       
         
           
               
               
               
             
               
                   
               
               
                 r x  (local radius) 
                 at % of radius (r) 
                 % P (power in wind) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 0.01r 
                  1% 
                 0.01% 
               
               
                 0.10r 
                 10% 
                 1.00% 
               
               
                 0.15r 
                 15% 
                 2.25% 
               
               
                 0.20r 
                 20% 
                 4.00% 
               
               
                 0.30r 
                 30% 
                 9.00% 
               
               
                 0.35r 
                 35% 
                 12.25% 
               
               
                 0.50r 
                 50% 
                 25.00% 
               
               
                 0.7071r 
                 70.71%   
                 50.00% 
               
               
                 1.00r 
                 100%  
                 100.00% 
               
               
                   
               
            
           
         
       
     
     75% of the wind&#39;s power is contained within the second half of the blade, from the center of rotation (50% down from the tip of the blade), and 84% of power in the section 60% from the tip of the blade. State of the art blades generally taper in the last 30% of the blade to the tip, which results in a low wind capture rate, as just over 50% of the wind&#39;s power is in that region. Additionally, the torque-creating moment increases outward from the center of rotation. Power is the product of torque and blade velocity, which comprise the factors that are taken into account in the three-dimensional designing of the instant invention. 
     The primary object of the invention is to provide a HAWT having increased wind capture and efficiency. By utilizing the Power Table and other factors, a blade geometry is created with an efficient planform and blade angles designed for low to medium wind speed operation, thus resulting in a reduced blade diameter compared to contemporary blades, for the same power output. The instant invention also has broader efficiency ranges over a larger range of wind speeds compared to contemporary blades, together with a lower rpm. Such improvements provide for additional windmills in a wind farm, thus increasing the wind farm&#39;s total output leading to a higher NPV (Net Present Value). Alternatively, using the same blade diameter as those of existing blades in a wind farm would also increase the NPV of the site. The advantage of a broader efficiency band is greater annual energy production. Low rpm compared to that of contemporary windmills considerably reduces the stress forces involved. Reduced blade diameter with greater energy output also facilitates the installation of windmills on homes to provide the full power required by an average urban home. 
     A further object of the invention is to provide a blade with increased efficiency in very low to medium wind velocities, which range from 5 mph to 35 mph (2.2 m/s to 15.65 m/s). 
     Another object of the invention is to minimize the airfoil&#39;s sensitivity to roughness, which is due to particulate matter, insects and the like. Roughness mainly affects the leading edge of a blade. 
     Yet another object of the invention is to provide a wide wind-velocity range, self-regulating blade that can be used with, but does not require the use of pitching devices. 
     The blade of the instant invention takes into account all critical factors, such as the radius to wind power relationship, the decreasing relative wind angles from the base of the blade to the tip and the changing Reynolds numbers between the base and the tip of the blade. 
     The crucial design parameters of the instant invention, which make it more efficient at low to medium wind speeds, are four fold:
         1. the precise design and proportions of the blade planform,   2. the precise designs of the airfoil profiles to provide superior lift to drag ratios,   3. the exact chord angles and their range and   4. the relationship of the blade&#39;s c/R ratio in the outboard section to the chord angles and the twist angles for peak performance, as given in the Parameter Relationships Graph.       

     As it will be apparent to those skilled in the art and in particular aerodynamicists, any alteration to the airfoil profile, blade planform or other aspect of a rotating blade will alter the blade&#39;s aerodynamic characteristics and can significantly affect the blade&#39;s performance. Thus the instant invention gives exact designs and parametric ranges for optimal performance. 
     All ranges provided herein take into account several factors, such as the chosen operational wind velocity range for the turbine, weight and type of fabrication material used, length of blades, type of electric generator used and its torque, blade rpm and energy requirements of the end user. These and other factors make it necessary to develop a wide enough range of design parameter options to allow for the necessary adjustments while keeping within the spirit of the instant invention and at the same time maintaining the integrity of the improvements of the instant invention. 
     DEFINITIONS AND PARAMETERS 
     Chord locations are given as a percentage of the ratios of the location of the chord from the center of rotation to the full size of the blade from the center of rotation to the tip or the blade radius, R. Chord size is the ratio of the chord length c, to R, as c/R. 
     Chord thickness is the ratio of the maximum thickness  t max of the profile, which is the perpendicular distance between the upper and lower profile surfaces where they are parallel and c, as t max /C.
 
Chord angles are relative to the plane of rotation of the blade.
 
Twist angle is the difference between the highest and the lowest chord angles of the blade.
 
The root of the blade is the section extending 25% from the center of rotation (0.25R).
 
The inboard section follows the root section and is the next 37.5% of the blade (0.375R).
 
The outboard section follows the inboard section of the instant invention and is the final 37.5% of the blade and includes the tip. In this section the c/R≦0.33. The value of c is averaged in this section and where all chord lengths may be equal. In the preferred embodiment c/R=0.314. θ=the angle between the lower side of a profile anywhere along the blade, for example as shown in  FIG. 3  toward the leading edge and the direction of the relative wind.
 
TSR=tip speed ratio which is the tip speed divided by the wind speed.
 
     The Parameter Chart below lists The Parameter Chart parametric relationships, proportionalities and ranges and gives values for the preferred embodiment. The chart also serves as an example since a range of variations through inter-parameter relationships are implied, as governed by the Parameter Relationships Graph, also given below. 
     
       
         
           
               
             
               
                   
               
               
                 Parameter CHART 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                   
                 Chord Locations on FIG. 1 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                   
               
               
                 FIGURES 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                 Chord Location 
                 6.25 
                 12.5 
                 18.75 
                 25 
                 31.25 
                 37.5 
                 43.75 
                 50 
                 56.25 
                 62.5 
               
               
                 % of R 
               
               
                 Chord Size(c/R) 
                 13.30 
                 13.50 
                 14.40 
                 16.24 
                 18.58 
                 21.40 
                 24.50 
                 27.39 
                 29.48 
                 30.67 
               
               
                 as a % 
               
               
                 Chord Thickness 
                 29 
                 26.30 
                 22.20 
                 17.7 
                 13.64 
                 11.31 
                 9.79 
                 8.67 
                 7.69 
                 6.88 
               
               
                 (t max /c) as a % 
               
               
                 Chord Angle 
                 22.80 to 23 
                 27.59 to 28 
                 31 
                 32 to 32.35 
                 31 to 31.26 
                 28.47 to 29 
                 25 
                 21.86 to 22 
                 19 to 19.20 
                 17 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Chord Locations on FIG. 1 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
                   
               
               
                   
                 FIGURES 
               
               
                   
                 Chord Location 
                 68.75 
                 75 
                 81.25 
                 87.5 
                 93.75 
                 98.75 
               
               
                   
                 % of R 
               
               
                   
                 Chord Size(c/R) 
                 31 to 31.18 
                 31 to 31.30 
                 31 to 31.20 
                 30.85 to 31 
                 29.51 to 31 
                 30.21 to 31 
               
               
                   
                 as a % 
               
               
                   
                 Chord Thickness 
                 6.30 
                 5.74 
                  5.17 
                 4.73 
                 4.45 
                  4.30 
               
               
                   
                 (t max /c) as a % 
               
               
                   
                 Chord Angle 
                 15 to 15.20 
                 13.70 to 14 
                 12.50 to 13 
                 11.60 to 12 
                 10.80 to 11 
                 10 to 10.30 
               
               
                   
                   
               
               
                   
                 Note: 
               
               
                   
                 This chart is given only to serve as an illustration. Other variations of these parameters are implied to accommodate smaller chord sizes using the Parameter Relationships Graph. The values and their interrelationships in this chart apply to the preferred embodiment. 
               
            
           
         
       
     
     The Parameter Relationships Graph, as shown in  FIG. 16  illustrates a chord angle graph z with its +5° to −10° range illustrated by the other two graphs on either side of it. The c/R ratios given apply only to the outboard section of the blade, where in this section c/R≦0.33 (c is averaged for the section) and where all chords may have the same length. (See parameter chart above). The graph illustrates only relationships of specific chord angles to blade radius proportionalities and c/R ratios through blade tip termination points. 
     Using the Parameter Relationships Graph for the outboard section, the formula for parametric prediction or extrapolation is c/R=0.22/x, where x is the quantity along the x-axis and extends beyond 1.0. The x-axis represents the blade radius relationship to its chord angles and blade tip termination points and not the size of the blade. For instance, when using this formula for outboard average chord size of 7% of blade radius, the x-axis of the graph would extend to 3.14 to give the rest of the chord angles and the blade&#39;s peculiar twist angle. 
     For instance, the graph shows the termination point for the blade at its tip giving the full range of the chord angles, according to any chosen or determined c/R averaged ratio of the outboard section, where c/R≦0.33. The termination point  1 , for example, is for the averaged c/R=0.314 for the preferred embodiment. This results in a specific angle range across the length of the blade and its peculiar twist angle. When the averaged c/R ratio for the outboard section is chosen to be less, such as 0.275 or 0.232, then the termination points are at 2 and 3 respectively on the graph, thereby giving the blade additional lower angles and increasing the twist angles accordingly. This is also demonstrated in  FIG. 15  where parametric relationships and not size are illustrated, wherein the parametric relationships change as the c/R is changed within ranges given in the instant invention. Note that outboard chord ratios are used for convenience of application and that all other chord lengths and parameters are derived according to the Parameter Chart above in conjunction with the ranges given in the Parameter Relationship Graph, resulting in blade design variations in keeping with the spirit of the instant invention, including variations in the planform of the blade, such as those shown in  FIG. 15 . The letters X, Y and Z in  FIG. 15  indicate examples of the three planform variations of the blade  12 , with each having different c/R ratios. From the top down, for each graph on the Parameter Relationships Graph, the c/R ratios are diminishing, additional lower angles are added to the blade and the twist angles are increasing. 
     For larger blades, load and stress issues can be calculated and applied to data pertaining to the instant invention, in order to arrive at the optimum chord lengths and still maintain the spirit of the instant invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a planform view of the horizontal axis wind turbine (HAWT) showing examples of sixteen chord locations of airfoil profiles, which are equally spaced longitudinally across the three sections of the blade. 
         FIG. 2  shows a perspective view of the HAWT as shown in  FIG. 1 . 
         FIGS. 3 to 12  give examples of ten equally spaced profiles at the first ten chord locations as shown in  FIG. 1 , from the centerline.  FIG. 12  is representative of the remaining six profiles in the locations as shown in  FIG. 1 , where the chord angles and blade thicknesses continue to reduce. These profiles essentially consist of two basic profile families, as depicted in these figures. The root family of profiles is referred to as family A profiles and the rest as family B profiles, both for Reynolds numbers of at least 1,000,000. 
         FIG. 13  illustrates an example of an alternate family C profiles, as used in the second embodiment and  FIG. 14  is an example of another alternate family D profiles, as used in the third embodiment. 
         FIG. 15  X, Y and Z are planform views of the HAWT showing how a change in chord size affects the shape of the blade, without affecting the blade&#39;s sectional proportionalities. 
         FIG. 16  is a graph illustrating the parameter relationships of the HAWT. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The best mode for carrying out the invention is presented in terms that describe a preferred embodiment of a horizontal axis wind turbine  10  (HAWT  10 ). 
     The HAWT  10 , as shown in  FIGS. 1-16 , is comprised of at least two identical blades  12 , as shown in  FIGS. 1 and 2 . The blades are comprised of an aggregate airfoil profile, as shown by example in  FIGS. 3-14 . The blades  12  further comprised of a tip  14 , a leading edge  16 , a trailing edge  18  that is spaced from the leading edge  16 , a blade center line  20 , an upper surface  22  that extends from the leading edge  16  to the trailing edge  18  and across the tip  14  to the blade center line  20 , and a lower surface  24  that also extends from the leading edge  16  to the trailing edge  18  and across the tip  14  to the blade center line  20 . The HAWT  10  blade diameter is at least 3 feet (0.91 meters). 
     Each of the blades  12  is divided sequentially and longitudinally into a root section  28 , an inboard section  30  and an outboard section  32 . To complete the structure of the HAWT  10 , a hub  46  connects at least two blades. The hub  46  has means for being attached to a rotating shaft, such as located on an electric motor or a gearing system. The attachment means is well known in the prior art and therefore is not disclosed herein. 
     The parameters that define an airfoil profile  26  of the instant invention, are shown in  FIG. 3  and include: a pointed leading edge  16 , a pointed trailing edge  18 , an upper surface  22 , a lower surface  24 , and a chord line  52 .  FIG. 3  also shows the wind direction  50 , the relative wind direction  51 , the blade direction  58 , and the plane of rotation  60  as a reference point for profile orientation. 
     The root section  28  is comprised of family A profiles, as exemplified in  FIGS. 3-6 , at selected chord locations. The inboard section  30  and outboard section  32  are comprised of family B profiles, as exemplified in  FIGS. 7-12 , at selected chord locations.  FIG. 12  also exemplifies a profile used for the entirety of the outboard section  32 , whereupon the chord size, the chord thickness and chord angles change, as shown in the parameter chart infra. The blade tip  14  is curved to the radius in the platform to reduce tip turbulence. Such a curve reduces high and low pressure points at the tip  14 , which helps reduce tip drag and noise. 
     As also shown in  FIG. 1 , the root section  28  comprises 25% of the blade&#39;s length and the inboard and the outboard sections  30  and  32  each comprise 37.5% of the blade&#39;s length. The lower surface  24  of each family of profiles is greater than the upper surface  22 , thereby creating a lift based on pressure differential according to Bernoulli&#39;s principle. Additionally, where family B profiles are used, the concave upper surface increases the pressure differential The pointed leading edge  16 , as shown in  FIG. 3 , creates a localized vortex  54  under the blade&#39;s leading edge  16 . This low pressure further improves the blade&#39;s lift to drag ratios, thus providing a broader power coefficient curve over a larger band of wind velocities then contemporary blades. This results in greater annual energy production as computed using the Weibull or Rayleigh distribution for a wind farm. The combination of a cambered lower surface  24  and the vortex  54  produces optimum performance in the wind velocity range of 5 mph (2.2 m/s) to 35 mph (15.65 m/s). The blades  12  can be fabricated of solid material for smaller blade diameters of up to 7.5 feet (2-3 meters). Hollow blades are fabricated for larger blade diameters. 
     The novel airfoil profiles of the instant invention gradually change longitudinally, in shape, size and in angle relative to the plane of rotation, thus giving varying aerodynamic characteristics along the blade for optimum performance. 
     A gradual augmentation of the pressure differential between the upper and lower surfaces of the airfoil profiles is accomplished by utilizing an increasing concave depth of the upper surface of the family B profiles, in the inboard and outboard sections of the blade, which combine with exponentially decreasing blade chord angles and a high twist. The combination causes the blade to operate at higher efficiencies, with a broader power coefficient against wind velocity compared to contemporary blades. The blade twist as shown in the Parameter Relationships Graph, is a combination of chord angles that exponentially increase in the root section and then exponentially decrease in the inboard and outboard sections, toward the blade tip. However, exponentially decreasing chord angles may be used throughout the blade. 
     In order to protect the surfaces of the blade as well as minimize the surface coefficient of friction, erosion and corrosion and reduce sensitivity to roughness, at least the leading edge is coated with protective material. The protective material includes gloss paint, resin-based material, fluoropolymers, thermoplastic resin or Teflon™, to provide effective erosion control for the leading edge of the wind turbine, with several other approaches and products also available. For instance, anti-erosion strips bonded to the leading edge may be used. Examples of anti-erosion strips are a polymeric tape or a polymeric coating onto a metal leading edge strip. Examples of metals of the strip are nickel and titanium (1 mm thick). Nickel-steel erosion strips can also be used. There are scratch resistant paints as well as 3M™ Wind Tape 8608, 8609 and Blade Tape 8671 (polyurethane protective tapes), specially designed for this purpose. There is also PropGuard™, which is an FAA approved anti-abrasion product, AeroKret™ coating for general protection of blades and CeRam-Kote™ family of high performance industrial coating products. Most of these products are designed to protect high-performance helicopter blade leading edges, which is far more demanding than protecting windmill blades. The degree of robustness of the erosion and corrosion control depends on the environment the turbine is used in. For instance, where much rain is expected, a stronger protective material would be used to protect the blades, particularly the leading edge. 
     Each profile has sharp leading and trailing edges. A sharp leading edge helps in deflecting particulate matter, insects and airborne contaminates due to the airflow and the vortex produced, thus reducing roughness. This feature, together with the airfoil profiles of the instant invention which are largely insensitive to roughness, along with the application of the protective coatings which have low surface coefficient of friction, minimize overall blade sensitivity to roughness. 
     The blade tip is curved to the radius of its rotation in the planform, which reduces drag and noise at the tip. The drag is typically caused by turbulence that is generated due to points of high and low pressure on the tip of a rotating blade when the tip is not curved to its radius of rotation. 
     The HAWT&#39;s coning angle ranges from 0° to 5°. 
     The operation of the instant invention is based on two means for achieving lift: the use of Bernoulli&#39;s principle and the use of a vortex. Contemporary blade utilizes a single means, which is Bernoulli&#39;s principle, to create lift. In the instant invention, Bernoulli&#39;s principle is utilized at the rear of the airfoil&#39;s lower surface  24 , as shown in  FIG. 3 . The arrow indicates the blade direction  58  and  60  represents the plane of the blade&#39;s rotation. The chord line  52  shows the blade angle relative to the plane of rotation  60 . A low-pressure zone is created at the lower surface  24  of the airfoil profile, toward the trailing edge  18  in the vicinity of a camber  56 , which provides one of the two lift vectors for the blade. The second lift vector is provided at the front of the lower surface  24  of the profile  26  due to the blade&#39;s sharp leading edge, which provides a low-pressure zone in the form of a vortex  54 . This combination of two forms of creating lift is more effective than just the use of Bernoulli&#39;s principle. A further lift improvement is achieved through the increase in the pressure differential between the upper surface  22  and the lower surface  24  of the inboard and outboard sections of the blade by the use of an increasing concave curvature  44  of the upper surface  22 , in the family B profiles, as shown in the example of  FIG. 12 . 
     The family A and B profiles of the preferred embodiment are designed for Reynolds numbers of at least 1,000,000. 
     The Parameter Relationships Graph shown supra illustrates a chord angle graph z of the preferred embodiment, relative to a blade radius, with a range as given in the Parameter Chart given supra. The c/R ratios given apply only to the outboard section of the blade where c is averaged for this section and c/R=0.314 for the preferred embodiment. All chords may have the same length in this section. The graph illustrates only parametric relationships and proportionalities to specific chord angles. In the preferred embodiment, the blade radius termination at the tip is at 10° for outboard section&#39;s value of c/R at 0.314, as illustrated by graph z. Furthermore, the Parameter Chart gives relative values and ranges applicable to the preferred embodiment. The chord lengths and other parameters for the rest of the blade sections are derived from the parameter relationships in the Parameter Chart. 
     In a second embodiment, family C profiles, an example of which is shown in  FIG. 13 , is used to replace profiles, at least in one section of the blade. 
     In a third embodiment, family D profiles, an example of which is shown in  FIG. 14 , is used to replace profiles, at least in one section of the blade. 
     While the invention has been described in detail and pictorially shown in the accompany drawings it is not to be limited to such details, since many changes and modifications may be made to the invention without departing from the spirit and the scope thereof. Hence, it is described to cover any and all modifications and forms, which may come within the language and scope of the claims.