1is the kinematic viscosity of air (1:51 10 5) and c is the chord length of the airfoil (10.16 cm). Re= V 1c 1 (1) The free-stream velocity was found to be 22.8 m=sand the Reynolds number was 153,600. Next, using MATLAB (see appendix B for code), both the upper and lower pressure readings were non. Details: Dat file: Parser (n10-il) N-10 N-10 airfoil Max thickness 11.2% at 30% chord. Max camber 3.6% at 40% chord Source UIUC Airfoil Coordinates Database Source dat file The dat file is in Selig format. Microsoft Windows 10 (64-bit only), 8.1 (32-bit & 64-bit), or 7 SP1 (32-bit & 64-bit) 1 GHz or faster processor. RAM, 32-bit: 2 GB, 64-bit: 4 GB. Disk space: 4.0 GB. 1360 x 768 display resolution with True Color. How To Install Airfoil? Download Airfoil 5.7.0 from below. Download Crack and Install It. After installation Extract the files as.
Rogue Amoeba has released Airfoil 5.8.7, updating its Audio Capture Engine backend to version 11.0 and adding preliminary compatibility with macOS 10.15 Catalina. The Audio Capture Engine is now required to use Airfoil, and you’ll be prompted to install it if it isn’t installed already. The wireless audio broadcasting app also reorganizes the menus shown by both Airfoil and Airfoil Satellite for better clarity, removes the “old-style hijacker” option from Airfoil’s Hidden Preferences, and now requires a minimum of 10.12 Sierra. ($29 new with a 20% discount for TidBITS members, free update, 18.8 MB, release notes, macOS 10.12+)
Carving the Blades
The blades are perhaps the most important part of our wind turbine -they are the ‘engine’ that drives our generator. These wind turbineblades have a simple airfoil and when finished they’ll look (and work)a bit like airplane wings. This design is a simple one. It’s acompromise we made keeping the following things in mind: efficiency,strength, cost and availability of materials, and ease of construction.Before you start a few terms should be defined. The 'tip' ofthe blade is the end that's at the very outer diameter - farthest awayfrom the alternator. The ‘front’ of the blade is the surface that facestowards the wind, it’s flat and angled a bit. The ‘back’ of the bladeis facing away from the wind and it’s rounded in shape. The ‘Root’ isthe inside of the blade, closest to the hub and the alternator. The‘Leading Edge’ is the edge of the blade that gets there first (if itwere an airplane wing then the leading edge is the front of the wing).The ‘trailing edge’ is the edge is the edge of the blade that getsthere last (if it were an airplane wing it would be the back edge ofthe wing). The ‘Pitch’ of the blade is the angle between the surface ofthe front of the blade, and the plane of the blade’s rotation. Itchanges over the length of the blade. The Chord of the blade is thewidth (the distance between the leading edge and the trailing edge) andit gets less (the blade gets narrower) as the diameter gets larger. Thethickness of the blade is the thickness at the ‘fattest’ point in theairfoil.
The simplest material to build your blades from is commonpine, or fir 2 x 8 lumber. Typically a planed 2 x 8 is 7.5 inches wideand 1.5” thick, so the plan is based upon that. Pine and fir have goodstrength to weight characteristics. Very hard, or very soft woodsshould be avoided. The very best choice is probably clear (knot free)Sitka Spruce, but it’s expensive and hard to find. Most lumber yardshave perfectly acceptable material. Generally you should use conifersalthough the very lightest ones might be too weak. I would avoidRedwood. The wood should be dry and as knot free as possible. Oftentimes we build ours from laminated Red Western Cedar 2 x4’s, but thatadds an extra step and it’s not necessary - but it does make for astrong, lightweight blade. Whatever you find, you need 3 boards about7.5 inches wide, 1.5 inches thick and 60 inches (5 feet) long.
There are a variety of tools you could use. A draw knife isalmost a must have. Chisels, hammers, sand paper, planes and other woodworking/carving tools are handy. Some of the work at the beginning ofthe project involves removing large pieces of the board and a band sawis very useful - but not necessary. A hand held power planer is nicebut hand planes work almost as well and they’re much quieter and morepeaceful to work with. This whole project can be done fairly easilywith hand tools only.
The instructions will describe how to carve a single blade.You need to make three of them. We suggest you make all three at onetime rather than making one at a time. There are several operationsinvolved, it’s better to do one operation to each blade and work themall along together, they’ll come out more alike that way. If youperform an operation on one blade… do it to the other two before youmove along to the next step.
Find a some lumber!
(For all the CAD images on this page right click on them, andselect 'veiw image' to see the full sized drawing)
Start with three 2 x 8 boards, 7.5 inches wide, 1.5 inchesthick and 60 inches (5 feet) long. Hopefully its free (or mostly freeof knots). Try to pick lumber with nice straight grain, the morevertical the better.
Cut out the shape of the blades
Pictured above is the shape of the blades. You can see how theblade is tapered. At the tip (radius = 60 inches) its 3 inches wide. Atthe half way point (Radius = 30 inches) it’s 6 inches wide. Draw a linebetween those two points and extend it to where it meets the edge ofthe board (this will be somewhere around radius 14 inches but it canvary depending on the width of your lumber) . You can either make atemplate and trace it onto all three blades, or just lay it out on oneblade and cut out the profile, then trace it to the other three. Cutout the blades with a band saw, circular saw or whatever you happen tohave available.
Pictured above is detail of the root of the blade. Thisdrawing will help you with the layout. You need a 120 deg angle at theroot so all three blades fit together tightly. Lay this out on allthree blades and cut them out.
Taper the thickness of the blade
As the blade gets narrower towards the tip it also getsthinner. The picture above shows how to taper the thickness of theboard. The top of the image is the front of the blade and you don’ttaper that part. All the material is removed from the bottom of theblade. The edge view is looking at the board from the leading edge, the’end’ view shows the cross section of the blade (white) and the scrap(darkened) at the tip, R= 30 inches and R= 12 inches. It’s better to betoo thick than too thin at this point - be sure not to get things toothin or the blade will be weakened. The dimensions we give forthickness in the drawing are the absolute minimum.
Getting the board thickness right with a band saw
A band saw is probably the best tool for cutting the boardthickness. Give yourself room for slop - don’t crowd the line. Whencutting this with a band saw its possible the board will not beperfectly square with the table and it’s easy to get differentthickness on one side than the other so give yourself room! The bandsaw is useful for removing most of the scrap. After that it’s best tofinish the job with a hand plane or a power planer.
Calipers work well for making sure you’ve got the thicknessright throughout the length and width of the blade. If you don’t have aband saw the whole job can be done with a plane or planer (or even adraw knife) - it just takes longer and makes more mess. When finishedthe back of the blade should be smooth, and square with the sides.
Carve the pitch on the front of the blade
Airfoil 5 8 7 X 100
At the tip of the blade the pitch is about 3 deg. At thecenter (R=30 inches) it’s about 6 deg. Near the root, where we stopcarving it’s as steep as our board will allow. The drawings do notdiscuss the angle of pitch,. Instead they show the amount of wood thatmust be removed from the blade along the trailing edge. The image mightseem a bit confusing. In the image (center, end view) you‘re looking atthe leading edge of the blade, and the darkened area is the materialthat must be removed from the trailing edge. Turn your unfinished bladearound so you’re looking at the trailing edge, and measure down fromthe front of blade and make marks at R=12 inches, R=30 inches and atthe tip(R=60 inches). At R=12 inches you’ll be removing all but 1/8inch of the wood from the board. (in other words the pitch will be sosteep here that it occupies almost the full board thickness, you leave1/8” only for a bit of strength). At R=30” you need to measure downfrom the top of the board 5/8 inch. At the tip measure down 5/32” andmake your mark there. Then connect the dots and you’ll have a linealong the trailing edge of the blade to carve down to. To carve thepitch of the blade you’ll be carving between two lines. One is the oneyou just drew along the trailing edge, the other is the leading edge ofthe blade (the corner between the front of the blade and the leadingedge). Do not disturb that corner of the board, but use it as a line.The ‘edge view’ images in the picture show this fairly well.
Curfing the blade with a saw and knocking out chunks with achisel
Things get a little different as you approach the root. Ifyou look at the image the carving stops near the root of the blade, youneed to draw a line here as shown in the image past which you’ll not becarving anymore. The exact shape and location of this is not critical,but it’s nice to make all three blades the same. Best is to make atemplate for this and trace it onto all three blades. As the carvedsurface approaches this line (near the root) it will taper up to fullboard thickness. Things 3 11 20.
roughing out the front of the blade with a drawknife
Once you get started it should all seem fairly easy. A drawknife is a great tool for removing lots of wood fast. A hand plane, ora power planer also make pretty quick work of things. Near the root,where the carving is deep and it tapers out into the thickness of theboard it’s sometimes best to cut lots of slots between the lines with ahand saw (one every inch or so) and then remove the wood between theslots with a chisel and mallet. One you‘ve carved down right to theline, smooth and flatten the surface with a plane and/or sand paper.Use a straight edge between the leading and trailing edges - the bladeshould be flat.
Carving the back of the blades
All that’s left to finish the job is to carve the airfoilprofile on the back side of the blades. As a rule the thickest part ofthe airfoil is always 1/3 of the way back from the leading edge. (inother words, the blade is 3 inches wide at the tip, so the fattest partof the airfoil will be one inch back from the leading edge, at R=30inches the blade is 6 inches wide so the fattest part of the airfoilwill be 2 inches back from the leading edge). Another general rule isthat the airfoil is about 1/8 as thick as it is wide. This ratiochanges gradually as you approach the root so that at near the rootit’s about 1/6 as thick as it is wide. This is not terribly critical solong as you’re close, but you never want to be less than 1/8 as thickas you are wide. At the tip the blade is 3 inches wide, so the thickestpart of the airfoil should be about 3/8 inch thick. Anything betweenabout 3/8 inch and 1/2 inch will be OK at the tip, it should not bemore or less than that though.
working the back of the blade with a drawknife
A drawknife is a good tool for roughing out the back side ofthe blade. It also moves along very quickly with a hand plane or apower planer.
carving the airfoil with a power planer
Airfoil 5 8 7 X 108
So turn the blade over so you’re looking at the back. At R=12inches measure back 1/3 of the way from the leading edge to thetrailing edge (the blade is 7.5 inches wide at this point so measureback 2.5 inches from the leading edge) and mark it. Do the same thingat the tip (it’s 3 inches wide so measure back 1 inch). Draw a straightline between the marks. This line marks the thickest part of theairfoil and it should never be disturbed, it’s the one place on theback of the blade where you’ll do no carving.Between this line and the leading edge you need to carve a nice roundedsurface as shown in the ‘end views’ in the image. Between the line andthe trailing edge it could be slightly rounded but almost a flatsurface. As with all other steps, it’s best to do one operation to eachblade so they come out the same. I find that even a change in mood canaffect your final work, so it’s good work along all three blades at thesame time. Once you have this roughed out then finish it with sandpaper. The leading edge of the blade should be rounded . There shouldbe no sharp surface between the front of the blade and the back of theairfoil. As the airfoil approaches the root of the blade (around R=12inches) is should just taper out to the original profile of the board.This area involves some concave surfaces which are impossible to dowith a plane. Best is to use a draw knife or a spoke shave. Thetrailing edge should be brought down fairly thin (about 1/16 inch) andfairly sharp. Ideally it should be very sharp, but you don’t want tomake it so thin that it’s very fragile.Now all you have left is to assemble the blades. We’ll discuss that inthe next section.