Blades for a wind generator made of PVC pipe. Calculation of wind generator blades

DIY PVC blades for wind turbine

PVC blades light, cheap, fast and easy to manufacture. How will you make them?

Wind energy, alternative energy, wind generator, DIY windmill, turbine

Choose the right size.

First you must decide for yourself what size blades you need. Then you can go to the store. It goes without saying that you should buy a piece of pipe the same length as the blades. The diameter of the pipe should be 5 times less than the length of the blade. For example, for 50 cm blades you need to buy a pipe with a diameter of 10 cm. You can make 4 blades from one piece of pipe.

So, you brought home a PVC pipe. In my example, for 50 cm blades, it looks like this.

Mark the PVC pipe.

The first step is to cut the pipe lengthwise into four equal sections. It is difficult to mark the cylindrical surface of a pipe without any tools. It is best to take a large piece of paper and wrap it tightly around the pipe. The edge of the sheet will help you draw a straight line on the pipe. The width of the sheet will be equal to the circumference. Then fold a piece of paper in half and mark half the circumference of the pipe. Finally, fold the sheet into four. Using this method, you can carefully draw straight lines along the entire length of the pipe. Now take a saw and cut the pipe into two halves.

(Alternative energy, wind generator, DIY PVC blades, PVC pipe blades, DIY blades, Wind energy, DIY windmill)

And now cut each half in half again:

Process four blanks.

Now, with each of the four blanks, we must do the following:

1) Make rectangular cuts about 5 cm long at the base of the future blades. Before cutting the workpieces, you need to drill holes in the corners so as not to violate the structural integrity of the material. The cuts should be made carefully, being careful not to touch the drilled holes with the saw.

2) Cut the workpieces diagonally from the end to the base.

All is ready.

Now everything is ready. We have four blades.

A wind generator made from a car generator can help in a situation where a private home does not have the ability to connect to a power line. Or it will serve as an auxiliary source of alternative energy. Such a device can be made with your own hands from scrap materials, using the best practices of folk craftsmen. Photos and videos will demonstrate the process of creating a homemade wind turbine.

Wind generator design

There is a huge variety of types of wind generators and drawings for their manufacture. But any design includes the following mandatory elements:

generator;
blades;
storage battery;
mast;
the electronic unit.

With some skills, you can make a wind generator with your own hands

In addition, it is necessary to think through the control and distribution system of electricity in advance and draw an installation diagram.

Wind wheel

The blades are perhaps the most important part of a wind generator. The operation of the remaining components of the device will depend on the design. They are made from different materials. Even from a plastic sewer pipe. Pipe blades are easy to manufacture, inexpensive and not susceptible to moisture. The procedure for manufacturing a wind wheel is as follows:

It is necessary to calculate the length of the blade. The diameter of the pipe should be equal to 1/5 of the total footage. For example, if the blade is one meter long, then a pipe with a diameter of 20 cm will do.
Using a jigsaw, cut the pipe lengthwise into 4 parts.
From one part we make a wing, which will serve as a template for cutting out subsequent blades.
We smooth out burrs on the edges with abrasive.
The blades are fixed to an aluminum disk with welded strips for fastening.
Next, the generator is screwed to this disk.

Blades for wind wheel

After assembly, the wind wheel needs balancing. It is mounted horizontally on a tripod. The operation is carried out in a room closed from the wind. If the balancing is carried out correctly, the wheel should not move. If the blades rotate on their own, then they need to be sharpened until the entire structure is balanced.

Only after successful completion of this procedure should you proceed to checking the accuracy of rotation of the blades; they should rotate in the same plane without distortion. Please allow 2mm error.

Generator assembly diagram

Mast

To make a mast, an old water pipe with a diameter of at least 15 cm and a length of about 7 m is suitable. If there are buildings within 30 m of the intended installation site, then the height of the structure is adjusted upward. For efficient operation of the wind turbine, the blade is raised above the obstacle by at least 1 m.

The base of the mast and the pegs for securing the guy wires are concreted. Clamps with bolts are welded to the stakes. For guy wires, galvanized 6 mm cable is used.

Advice. The assembled mast has considerable weight; if installed manually, you will need a counterweight made of a pipe with a load.

Generator conversion

To make a windmill generator, a generator from any car is suitable. Their designs are similar to each other, and the modification boils down to rewinding the stator wire and making a rotor with neodymium magnets. Holes are drilled in the rotor poles to fix the magnets. Install them alternating poles. The rotor is wrapped in paper, and the voids between the magnets are filled with epoxy resin.

Car generator

In the same way, you can remake the engine from an old washing machine. Only the magnets in this case are glued at an angle to avoid sticking.

The new winding is rewound along the reel onto the stator tooth. You can make a random winding, depending on who you are comfortable with. The greater the number of turns, the more efficient the generator will be. The coils are wound in one direction according to a three-phase circuit.

The finished generator is worth testing and measuring data. If at 300 rpm the generator produces about 30 volts, this is a good result.

Generator for a windmill from a car generator

Final assembly

The generator frame is welded from a profile pipe. The tail is made of galvanized sheet. The rotary axis is a tube with two bearings. The generator is attached to the mast in such a way that the distance from the blade to the mast is at least 25 cm. For safety reasons, it is worth choosing a calm day for the final assembly and installation of the mast. When exposed to strong winds, the blades can bend and break against the mast.

To use batteries to power equipment that operates on a 220 V network, you will need to install a voltage conversion inverter. The battery capacity is selected individually for the wind generator. This indicator depends on the wind speed in the area, the power of the connected equipment and the frequency of its use.

Wind generator device

To prevent the battery from being damaged by overcharging, you will need a voltage controller. You can make it yourself if you have sufficient knowledge in electronics, or buy a ready-made one. There are many controllers available for sale for alternative energy production mechanisms.

Advice. To prevent the blade from breaking in strong winds, install a simple device - a protective weather vane.

Wind generator maintenance

A wind generator, like any other device, requires technical monitoring and maintenance. To ensure uninterrupted operation of the windmill, the following work is periodically carried out.

Wind generator operation diagram

The current collector requires the most attention. Generator brushes need to be cleaned, lubricated and preventatively adjusted every two months.
At the first sign of a malfunction of the blade (shaking and imbalance of the wheel), the wind generator is lowered to the ground and repaired.
Every three years, metal parts are coated with anti-corrosion paint.
Regularly check the fastenings and tension of the cables.

Now that the installation is complete, you can connect devices and use electricity. At least while it's windy.

Do-it-yourself generator for a windmill: video

Wind generator for a private home: photo

The use of alternative energy sources is one of the main trends of our time. Clean and affordable wind energy can be converted into electricity even in your home by building a wind turbine and connecting it to a generator.

You can build blades for a wind generator with your own hands from ordinary materials, without using special equipment. We will tell you which blade shape is more efficient and help you choose the appropriate drawing for a wind power plant.

A wind generator is a device that allows you to convert wind energy into electricity.

The principle of its operation is that the wind rotates the blades, sets in motion the shaft, through which the rotation is supplied to the generator through a gearbox, which increases the speed.

The operation of a wind power plant is assessed by KIEV - wind energy utilization factor. When a wind wheel rotates quickly, it interacts with more wind, which means it takes more energy from it.

There are two main types of wind generators:

horizontal.

Vertically oriented models are built so that the propeller axis is perpendicular to the ground. Thus, any movement of air masses, regardless of direction, sets the structure in motion.

This versatility is an advantage of this type of wind turbine, but they are inferior to horizontal models in terms of productivity and operating efficiency.

A horizontal wind generator resembles a weather vane. In order for the blades to rotate, the structure must be turned in the desired direction, depending on the direction of air movement.

To monitor and capture changes in wind direction, special devices are installed. The efficiency with this screw arrangement is significantly higher than with a vertical orientation. For domestic use, it is more rational to use wind generators of this type.

What blade shape is optimal?

One of the main elements of a wind generator is a set of blades.

There are a number of factors associated with these parts that affect the efficiency of the windmill:

size;
form;
material;
quantity.

If you decide to design blades for a homemade windmill, you must take all these parameters into account. Some believe that the more wings on a generator propeller, the more wind energy can be produced. In other words, the more the merrier.

However, this is not the case. Each individual part moves against air resistance. Thus, a large number of blades on a propeller requires more wind force to complete one revolution.

In addition, too many wide wings can cause the formation of a so-called “air cap” in front of the propeller, when the air flow does not pass through the windmill, but goes around it.

Form matters a lot. The speed of the propeller depends on it. Poor flow causes the formation of vortices that slow down the wind wheel

The most efficient is a single-blade wind generator. But building and balancing it with your own hands is very difficult. The design turns out to be unreliable, although with a high efficiency. According to the experience of many users and manufacturers of wind turbines, the most optimal model is a three-bladed one.

The weight of the blade depends on its size and the material from which it will be made. The size must be selected carefully, guided by calculation formulas. It is better to process the edges so that there is a rounding on one side and a sharp edge on the opposite side.

The correctly selected blade shape for a wind generator is the foundation for its good operation.

The following options are suitable for home production:

sailing type;
wing type.

The sail type blades are simple wide stripes, like those on a windmill. This model is the most obvious and easiest to make. However, its efficiency is so low that this form is practically not used in modern wind generators. The efficiency in this case is about 10-12%.

A much more effective form is the blades of the winged profile. It involves the principles of aerodynamics that lift huge aircraft into the air. A screw of this shape is easier to set in motion and rotates faster. The flow of air significantly reduces the resistance that the windmill encounters along its path.

The correct profile should resemble an airplane wing. On one side the blade has a thickening, and on the other there is a gentle slope. Air masses flow around a part of this shape very smoothly

The efficiency of this model reaches 30-35%. The good news is that you can build a winged blade yourself using a minimum of tools. All basic calculations and drawings can be easily adapted to your windmill and use free and clean wind energy without restrictions.

What are blades made from at home?

Materials that are suitable for the construction of a wind generator are, first of all, plastic, light metals, wood and a modern solution - fiberglass. The main question is how much labor and time you are willing to spend on making a windmill.

PVC sewer pipes

The most popular and widespread material for making plastic blades for wind generators is an ordinary PVC sewer pipe. For most home generators with a screw diameter of up to 2 m, a 160 mm pipe is sufficient.

The advantages of this method include:

low price;
availability in any region;
ease of operation;
a large number of diagrams and drawings on the Internet, extensive experience in use.

Pipes are different. This is known not only to those who make homemade wind power plants, but to everyone who has encountered the installation of sewerage or water supply. They differ in thickness, composition, and manufacturer. The pipe is inexpensive, so there is no need to try to reduce the cost of your windmill even more by saving on PVC pipes.

Poor-quality material of plastic pipes can lead to the fact that the blades will crack during the first test and all the work will be done in vain

First you need to decide on the pattern. There are many options, each form has its own disadvantages and advantages. It might be worth experimenting first before cutting out the final version.

Since the price of pipes is low, and you can find them in any hardware store, this material is perfect for the first steps in modeling blades. If something goes wrong, you can always buy another pipe and try again; your wallet won’t suffer much from such experiments.

Experienced wind energy users have noticed that it is better to use orange rather than gray pipes to make wind turbine blades. They hold their shape better, do not bend after the wing is formed and last longer

Amateur designers prefer PVC, since during testing a broken blade can be replaced with a new one, made in 15 minutes right on the spot if a suitable pattern is available. Simple and fast, and most importantly – affordable.

Aluminum – thin, light and expensive

Aluminum is a lightweight and durable metal. It is traditionally used to make blades for wind turbines. Due to its low weight, if you give the plate the desired shape, the aerodynamic properties of the propeller will be excellent.

The main loads that a windmill experiences during rotation are aimed at bending and breaking the blade. If the plastic quickly cracks and fails during such work, you can count on an aluminum screw for much longer.

However, if you compare aluminum and PVC pipes, metal plates will still be heavier. At high rotation speeds, there is a high risk of damaging not the blade itself, but the screw at the attachment point

Another disadvantage of aluminum parts is the complexity of manufacturing. If the PVC pipe has a bend that will be used to impart aerodynamic properties to the blade, then aluminum, as a rule, is taken in the form of a sheet.

After cutting out the part according to the pattern, which in itself is much more difficult than working with plastic, the resulting workpiece will still need to be rolled and given the correct bend. It will not be so easy to do this at home and without tools.

Fiberglass or fiberglass - for professionals

If you decide to approach the issue of creating a blade consciously and are willing to spend a lot of effort and nerves on it, fiberglass will do. If you have not previously dealt with wind generators, starting your acquaintance with modeling a windmill made of fiberglass is not the best idea. Still, this process requires experience and practical skills.

A blade made of several layers of fiberglass bonded with epoxy glue will be strong, light and reliable. With a large surface area, the part turns out to be hollow and practically weightless

For manufacturing, fiberglass is used - a thin and durable material that is produced in rolls. In addition to fiberglass, epoxy glue is useful for securing the layers.

Work begins by creating a matrix. This is a blank that represents a mold for a future part.

The matrix can be made of wood: timber, boards or logs. The volumetric silhouette of half the blade is cut out directly from the massif. Another option is a plastic mold.

It is very difficult to make a blank yourself; you need to have in front of your eyes a ready-made model of a blade made of wood or other material, and only then a matrix for the part is cut out from this model. You need at least 2 such matrices. But, having made a successful shape once, it can be used many times and this way you can build more than one windmill.

The bottom of the mold is thoroughly lubricated with wax. This is done so that the finished blade can be easily removed later. Lay a layer of fiberglass and coat it with epoxy glue. The process is repeated several times until the workpiece reaches the desired thickness.

When the epoxy glue has dried, half of the part is carefully removed from the matrix. They do the same with the second half. The parts are glued together to form a hollow three-dimensional part. Lightweight, durable, and aerodynamically shaped, the fiberglass blade is the pinnacle of excellence for the home wind farm hobbyist.

Its main disadvantage is the difficulty of implementing the idea and a large number of defects at first, until the ideal matrix is obtained and the creation algorithm is perfected.

Cheap and cheerful: wooden part for a wind wheel

A wooden blade is an old-fashioned method that is easy to implement, but ineffective at today's level of electricity consumption. The part can be made from a solid board of light wood, such as pine. It is important to choose a well-dried piece of wood.

You need to choose a suitable shape, but take into account the fact that the wooden blade will not be a thin plate, like aluminum or plastic, but a three-dimensional structure. Therefore, it is not enough to give the workpiece a shape; you need to understand the principles of aerodynamics and imagine the outline of the blade in all three dimensions.

You will have to use a plane to give the final look to the wood, preferably an electric one. For durability, the wood is treated with an antiseptic protective varnish or paint

The main disadvantage of this design is the large weight of the screw. To move this colossus, the wind must be strong enough, which is difficult to achieve in principle. However, wood is an affordable material. The boards suitable for creating a wind turbine propeller can be found right in your yard without spending a penny. And this is the main advantage of wood in this case.

The efficiency of a wooden blade tends to zero. As a rule, the time and effort that goes into creating such a windmill is not worth the result obtained, expressed in watts. However, as a training model or test piece, the wooden part has its place. And a weather vane with wooden blades looks impressive on the site.

Drawings and examples of blades

It is very difficult to make the correct calculation of a wind generator propeller without knowing the basic parameters that are displayed in the formula, as well as having no idea how these parameters affect the operation of the windmill.

It’s better not to waste your time if you don’t want to delve into the basics of aerodynamics. Ready-made drawings and diagrams with specified indicators will help you choose a suitable blade for a wind power plant.

Drawing of a blade for a two-blade propeller. Made from 110 diameter sewer pipe. The diameter of the windmill propeller in these calculations is 1 m

Such a small wind generator will not be able to provide you with high power. Most likely, you are unlikely to be able to squeeze more than 50 W out of this design. However, a two-blade propeller made of a light and thin PVC pipe will give a high rotation speed and ensure the operation of the windmill even in light winds.

Drawing of a blade for a three-bladed wind generator propeller made from a 160 mm diameter pipe. The estimated speed in this option is 5 with a wind of 5 m/s

A three-blade propeller of this shape can be used for more powerful units, approximately 150 W at 12 V. The diameter of the entire propeller in this model reaches 1.5 m. The wind wheel will rotate quickly and be easily started. The three-wing windmill is most often found in home power plants.

Drawing of a homemade blade for a 5-blade wind generator propeller. Made from PVC pipe with a diameter of 160 mm. Estimated speed – 4

Such a five-blade propeller will be able to produce up to 225 revolutions per minute with an estimated wind speed of 5 m/s. To build a blade according to the proposed drawings, you need to transfer the coordinates of each point from the “Front/rear pattern coordinates” columns to the surface of the plastic sewer pipe.

The table shows that the more wings a wind generator has, the shorter their length must be to produce a current of the same power

As practice shows, it is quite difficult to maintain a wind generator larger than 2 meters in diameter. If you need a larger windmill according to the table, consider increasing the number of blades.

You will become familiar with the rules and principles in this article, which outlines the process of performing calculations step by step.

Balancing a wind turbine

Balancing the blades of a wind generator will help make it work as efficiently as possible. To carry out balancing, you need to find a room where there is no wind or draft. Of course, for a wind wheel larger than 2 m in diameter it will be difficult to find such a room.

The blades are assembled into a finished structure and installed in the working position. The axis must be positioned strictly horizontally, level. The plane in which the propeller will rotate must be set strictly vertically, perpendicular to the axis and ground level.

A propeller that is not moving must be rotated 360/x degrees, where x = number of blades. Ideally, a balanced windmill will not deviate by 1 degree, but will remain motionless. If the blade has turned under its own weight, it needs to be adjusted a little, the weight reduced on one side, and the deviation from the axis eliminated.

The process is repeated until the screw is absolutely motionless in any position. It is important that there is no wind during balancing. This may skew test results.

It is also important to check that all parts rotate strictly in the same plane. To check, control plates are installed at a distance of 2 mm on both sides of one of the blades. During movement, no part of the screw should touch the plate.

To operate a wind generator with manufactured blades, you will need to assemble a system that accumulates the received energy, stores it and transmits it to the consumer. One of the system components is the controller. You will learn how to do this by reading our recommended article.

If you want to use clean and safe wind energy for your household needs and do not plan to spend a lot of money on buying expensive equipment, homemade blades from ordinary materials will be a suitable idea. Don't be afraid to experiment, and you will be able to further improve existing models of windmill propellers.

Wind generators, including homemade ones, are increasingly used as an alternative source of energy. A mast, turbine, weather vane and wind wheel are all that is needed to make a windmill. From this set you will only have to purchase an electric generator to convert wind energy into electrical energy. All other components can be made independently from scrap materials. The assembly of a wind wheel and the manufacture of wind generator blades will be discussed in this article.

Before assembling a wind generator yourself, you should decide on the power that needs to be obtained from the windmill. This power directly depends on the wind strength in the region, the diameter of the wind wheel and the number of blades. And if a person cannot influence the strength of the wind in any way, then the required parameters of the blades will have to be determined in advance. The table below shows the parameters of the wind wheel (wheel diameter for a certain number of blades) and the power generated by the wind generator at a wind speed of 4 m/s.

The table shows that a wind generator with a power of 50...100 kV can be made from scrap materials.

After determining the required number and dimensions of wind generator blades, you can proceed to their manufacture. To do this, you need to choose the type of blades: sail-type blades (like windmills) or wing-profile blades. Sail-type blades have a simple design, but they are capable of converting only 10-12% of the energy of the wind flow, since they do not use the aerodynamic capabilities of wind flows. The inner and outer sides of the wing profile blades have different areas, which creates a difference in air pressure on opposite sides of the wing. The resulting aerodynamic force makes the use of wind flow much more efficient, and the wind energy efficiency can reach 0.4 (40% of wind energy is converted into useful work).

PVC pipes, aluminum or fiberglass can be used as materials or blanks for the manufacture of wind generator blades.

Wind turbine blades made of PVC pipes

PVC pipes already have all the necessary characteristics for the manufacture of blades: they are light, strong enough, and have a curved shape. When using PVC pipes to make blades, it is worth remembering that plastic still does not have good characteristics in withstanding tensile loads. Therefore, due to the high rotation speed of the wind generator blades (the speed of movement of the final part of the blade of a two-bladed wind generator wheel is hundreds of meters per second), it is necessary to reduce the length of the blade and, thereby, increase the number of blades (in accordance with the table). In addition, the wall thickness of the PVC pipe must be at least 4mm.

As a template for the blades, you can use the drawing below, print it out, attach it to the wall of the pipe, circle it with a marker and cut the blade out of the pipe. The cut areas and the edges of the blades must be sanded and rounded.

To connect the blades, it is necessary to prepare a metal base on which all the wind generator blades will be attached. The dimensions of the disk must be selected individually, taking into account the parameters of the electric generator (output shaft diameter) that will be used for the windmill.

Aluminum wind turbine blades

Aluminum blades, compared to plastic ones, have better strength characteristics, both tensile and bending. However, a larger mass of blades will require additional reinforcements in the design of the wheel and mast of the wind generator. One of the possible options for manufacturing aluminum blades is shown below.

A significant disadvantage of aluminum blades is the difficulty in manufacturing, because... in any case, this will require aluminum blanks and special tools for metal processing and welding.

Fiberglass wind turbine blades

Fiberglass can be called an ideal material for the manufacture of wind generator blades due to its excellent strength, aerodynamic properties and weight. However, making fiberglass blades is a rather labor-intensive process that requires special skills and experience working with wood and fiberglass.

Templates of a wind wheel blade matrix with a diameter of 2 meters are given below.

To make blades from a wind generator, it is necessary to prepare a wooden matrix, which is machined from a wooden beam according to a template. After this, the mold is waxed and a layer of epoxy resin is applied, on which a sheet of fiberglass is laid. Then another layer of epoxy resin is applied on top of the fiberglass and another layer of fiberglass. One blade consists of 3-5 layers of fiberglass. After drying, we get half a wind generator blade. The resulting halves of the blades are glued together with epoxy resin, and a wooden plug is glued into the inner end, which will serve as the basis for attaching the blade to the wheel hub.

Balancing wind turbine blades

Once the wind generator blades are manufactured and the wheel is assembled, it is necessary to balance it.

When balancing, the wheel must rotate freely on the test bench, while the plane of the wheel connecting unit is strictly parallel to the vertical suspension. The balancing check is as follows: the wheel stops and is released. Then we turn the wheel manually at an angle equal to 360/number of blades, stop it again and release it. If a wheel that is stopped and released begins to rotate, it means that the part of the wheel that tends downwards is heavier. Having determined a heavier blade, it is necessary to grind off one of its edges in order to reduce its weight.

After equalizing the masses of all wind generator blades, you can perform one more test: install bars on both sides at a distance of 2 mm from the blades, and then make sure that the blades do not touch the bars when rotating.

After this, you can begin the final assembly and connection of the wind generator.

If you search and look on the Internet, many people make blades for their homemade wind generators from plastic pipes. Well, this is understandable, since sewer pipes are well suited for these purposes, accessible and cheap. But of course not everyone, they don’t particularly like the gray pipe, since it quickly deforms and is very weak. Red-colored pipes are most suitable; they hold their shape and have good strength. The best pipes are made of pure PVC, but now more and more of them are made from something unknown, including polypropylene and other materials, which are also not suitable for wind generator blades.

Well, that’s okay, the main mistake people make is making blades without any calculations and fitting them to the generator, but the blades are the part of the wind generator that converts wind energy, and how well they do this depends on the overall KIEV of the wind generator (wind energy utilization coefficient).

To calculate blades from PVC pipes, a simple but effective program was created in Excel format. In this program it is easy to calculate the screw for a specific generator. By entering the coordinates of the future blade, you can see how all the necessary parameters of the propeller change, these are revolutions at different wind speeds, KIEV, torque, starting and other parameters.

But many people cut out blades by eye, and I used a program to analyze a KIEV like the one in the screenshot below the blade; very often you see blades made from pipes of exactly this shape.

Such blades are often made, this is the simplest thing, just draw two lines on the pipe and cut it out, process the edges and you’re done. But the KIEV of such blades is all 0.2 in the three-blade version on small pipe diameters. The performance is better if you increase the number of blades to 6, 8, but the speed decreases, and as we know, we need the maximum power of the blades at the highest possible speed from each wind speed.

Below are screenshots of such a blade.

There is a three-blade propeller made from a 110-mm pipe with a diameter of 1.2 m, and maximum power at a speed of 3.8.

And this is already 6 blades, the result is a little bit better.

Also, a screw from a 160-mm pipe cut according to this principle also has a low KIEV and speed.

If there are 6 blades, then it is better.

You can also increase the diameter, for example, to 1.7 m and see.

The performance is better for larger screws cut from pipes of larger diameter, for example from a 320mm pipe.

And here is an Excel file with the last pipe 320mm in diameter - rasshet3D2.5Z5.5T3200mm.xls

Universal blade.

Especially for those who want to cut blades with a relatively high KIEV, I used a program to create a certain universal blade. It is cut a little more difficult, but has a higher KIEV and speed. On pipe diameters 110-160, such a blade has a KIEV of 0.27-0.33 with a speed of Z3.5-5.5, but on large propellers the KIEV exceeds 0.4 and the speed increases.

here is a screenshot for the 110th pipe and the 160th. If you lengthen the blade, then KIEV falls just a little bit.

Here is an Excel file with this blade - rasshet3D1500.xls

How to cut such a blade without a program.

Such a blade can be calculated very easily using a calculator. All calculations are based on the diameter of the pipe. First you need to divide the diameter of the pipe by 5, for example for the 110th pipe 110:5=22mm, and for the 160th pipe 160:5=32mm.

22*2=44 mm, distance from the root of the blade 0%,

Second 22*488mm, distance 15%,

Third 22*2.5=55mm, distance 50%,

The fourth is 22*2=44mm, the distance is 100% tip.

All these points need to be connected and this will be the front of the blade. To attach the blade, you need to draw another line on which holes for attaching the blade are drilled, the line is drawn 22 mm away from the first line.

After cutting, the edges of the blade must be processed in this way, since the calculation takes into account the processing of the edges in such a way that all angles along the length of the blade coincide with the calculated ones.

In the picture below I tried to show how this should be done. As I already wrote above, the diameter is taken as a basis and divided by 5, the resulting figure can be conventionally designated as X. Then there are numbers from this letter in the figure, this is the percentage by which X needs to be multiplied.

Then the following coordinates are obtained.

The first line is zero, this is the rear of the future blade.

And then the first point from the root 0%, can be designated as follows, point A-X-1-0%, where A is the point, X is the figure obtained by dividing the diameter by 5, 1 is the multiplier, 0 is the distance from the root blades - radius along the length of the blade.

Line for attaching the blade.

А-Х-1-0% = 22mm, blade radius 0mm

B-X-4-15% = 88mm, blade radius 112.5mm

B-X-2.5-50% = 55mm, blade radius 375mm

Г-Х-1-100% = 22mm, blade radius 750mm

Blade attachment line.

D-X-0.5 = 11mm

E-X-0.5 = 11mm

11 millimeters from the very first line - rear, towards the front, this line is for attaching the blade.

Here I hope everything is clear. This universal blade fits well with different pipe diameters, and the length of the blade can be lengthened or shortened. From a 110mm pipe you can make a propeller with a diameter of up to 1.5m, after that the blades will simply be very weak. From 160 to 1.8 m, etc. Moreover, the larger the pipe diameter and screw size, the better the KIEV.

But it’s better, of course, to calculate individually for the generator and the required wind speed. And if this is not possible, then you can use this universal blade and just remember how to cut. I have already tried a propeller with a diameter of 1.3 m from a 110 pipe, four blades, it works well, it is resourceful.