The introduction period is one of the most fun months at the WOT, where we meet new people that come here to learn and do fun activities. The first Intro activity was the Marble pump course. Here, kiddos learn how to use various pvc-forming skills to make a waterpump. It was once again remarkable to see how quickly a pile of pvc pipes turns into a big water fight, mostly with semi working water pumps. The kiddos were very excited about the technology and many WOT memories were made; And all this on the first activity.

This year’s soldering course had intro participants learning how to solder on prototyping boards by making a simple current limited LED circuit. The participants quickly took  the task upon them and quickly has a series of three LED’s glowing brightly (barring the LED’s lost through leaving out the resistors, may they Rest In Peace ☹).  With extra time left the participants were provided with a single pole double throw switch and instructed to design a circuit that would switch between the three LED’s and another one, also giving them some introductory knowledge to simple circuitry.

In preparation for the well drilling practical the next day, we were lectured by Menno about well drilling. During this lecture we were taught all kinds of drilling techniques while Menno talked about his own experiences. He showed us loads of demonstrations and actual drilling gear, which made the lecture very interesting to watch. Most importantly, the goal was set to drill at least 11 meters the next day, crushing the previous year's record of 9 meters.

Dragos: I was really excited to do the EMAS drilling as we had a lecture about it the day before. The actual drilling was way harder than I expected, especially on the hands, but it was fun to do. As tried to do a bit of everything, I can tell you that pumping was fun for the first five minutes, pulling the rope was not that hard if you had gloves on, otherwise you would get rope burn, and turning the drill was the most fun, but also the most exhausting part, in my opinion. All in all, I would do it again if the chance arises.

After a very successful GMA, where two old board members were freed from the WOT board, the remaining members gathered to play the greatest game ever played in the history of games: “WOT members, old and new, what do they know? Do they know things? Let’s find out!”

The game featured such categories as “Which myths have these two busty boys busted, and which myths busted these boys?” and “Get your gribby grabbers on those items and then tell us their diameters, lengths, or other measurements.”

After six nail biting rounds where WOT members showed off what they knew and learned many new things, everyone left a little wiser. And after only a little bit of cheating from the teams, Buurman and Buurman reigned supreme, winning the grand prize of six chocolate bars and wrapping up an eventful night.

The third Thursday of the introduction evenings brought a great opportunity for every broke student, both old and new: fix your bike for free! Participants quickly discovered what was really expected: to get their own hands dirty! Soon, bikes were flipped upside down, saddles removed, and wheels rolling around, where small groups teamed up to lend each other a helping hand. By the end of the night, a whole fleet of bikes, of both participants and WOTters, rolled out of the workshop in a better shape than when they had arrived that afternoon. We hope to have learned the participants an occasional practical skill along the way!

In the last week of the introduction period, we (the new WOTers) were instructed to make a shelf bracket out of steel. During this workshop course, we all had to pair up and were taught all kinds of techniques to process steel by older WOT members. These techniques included cutting & bending and most importantly: welding steel and using an angle grinder. At the end of the workshop course, everyone succeeded in making a shelf bracket. One too few to actually attach a bookshelf.

This is the last introduction activity and this evening was very similar to what we do on a normal Wednesday evening. We did not have that much turn up, but with the people that were at the WOT this evening we did a lot! We started fixing the Farmers’ pump, people practiced welding for an EMAS set that will be used for Wot Walks For Water and we continued building things for the hydroponics system. And in the end everyone helped clean the workshop and enjoyed the campfire afterwards. Now the new members are really ready for the WOT.

The Kick-In started with the introduction market: The place where new students get to meet the associations at the UT. One of these associations is, of course, the WOT; we too want to attract new members. Luckily, this year we got a very central spot on the market terrain. Quickly after setting up our stand, with our small portable windmill and the other demo setups (flamingo pump, mini Crete, and solar cooker), the first new students were attracted to our stand. This year, we saw faces of varying studies that were interested in the WOT, and by the end of the afternoon, we had a full mailing list of potential new members.

The MTAD lunch is the second opportunity for the WOT to attract new members. In the beginning new students were mainly enjoying lunch and did not come to the stand, but when their stomachs began to be filled, groups started forming at our stand. We gave the same explanations about what we do at the WOT, about our introduction activities (you can read a blog about that soon), and everything else they wanted to know about the interesting demo setups at our stand. It turned out that there were even more people interested during this lunch than during the intro market.

Due to the influx of new members of the WOT who studied TCS, this year the WOT had not one but two Kick-In Do-groups! One for ME and one for TCS!

The Kick-In for the WOT mechanical engineering do group was an absolutely amazing week, filled with campfires, parties, and most importantly, giving the new first years an amazing introduction to their new life at uni, and much more importantly, the WOT.

The week started out strong when a very enthusiastic (and only slightly hungover) pair of parents gave a speech about the WOT so good that it caused every first-year student in the room to put the WOT as their first choice. They ended up with 11 kiddos, soon adopting one more that night.

As the week went on, the 12 kiddos slowly started becoming more, as more first years learned about how amazing the WOT was. More started joining the do group, including one night where they started with 11 kiddos and ended the night with 18.

After 9 days straight of partying, jumping off bridges, getting sick, bakfietsen, storming the Bastille, and having fun, the week ended with the ultimate challenge: making the heroes breakfast on the last day of the Kick-In. 13 kiddos and Brodie set out to party all night and had the night of their lives, and after only one casualty, 12 kiddos made it back to enjoy sausages, eggs, and bread at the WOT to celebrate before promptly passing out from pure exhaustion.

The WOT Technical Computer Science Kick-In slightly differed from the ME one, but was just as great. We filled our week with campfires, board games, music, and parties.

On the first day, we made pancakes to convince people to join the WOT do group. But we found out people actually liked the WOT talk we gave so much that the pancakes were no longer needed to convince them. We talked to kiddos who wondered why we might build a windmill at 2 am, and kiddos who loved campfires. Our plan was to do as many of the activities this Kick-In could give us, so that our kiddos could find out what they were interested in, and we hoped they would also like the WOT. 

Eventually, we got 9 kiddos, one of whom was lost at first, but then was found a few days later. We started that day with pizzas, and when we had finished those, we showed the do-group around at the WOT terrain. We explained how easy it is to transport and build the Diever, and why the Kreta turned out not to be a great success, and what the PTB is used for. Our kiddos liked the WOT, and that is eventually where we spent most of our Kick-IN, with about half the do group becoming members during the week and starting some small projects in the workshop.

Overall, the Kick-In was a humongous success, which got many people excited to join the WOT. 

Last but not least, a few words about the faculty Kick-In. The first day of the faculty Kick-In, Deadalus kiddos swarmed the terrain to make their famous beerboards. Armed with pen and paper, they begin carefully sketching. To then, all at the same time, request a large amount of reciprocating sawing and hole drilling. This was no problem; the kiddos were delightful, and the BBQ that evening was delicious. The free beer also helped.

For the last two days of the faculty KickIn, the WOT once again had the pleasure of having Newton on our terrain. They came with heaps of pallets, bikes, and big blue water drums. The first day, they made their classic catapult, which once again proved to be harder than it looks. The WOT was treated to a great BBQ with plenty of beer as a reward for the volunteering. The second day, they brought back an old tradition: Raft building! With pallets, empty milk jugs, and two 200L water barrels per group, they embarked on their quest. It turned out to be quite the hassle to build a raft that has the buoyancy to hold up to people but is still stable so as not to fall over. It was an endearing sight to see! We hope to see the rafts return next year!

Can you hear that?? Far away… behind the horst… a dreadful but familiar sound can be heard faintly. It seems like Mariah Carey has defrosted once again, and All I Want for Christmas Is You echoes in the Kiwanda like it’s almost the 25th of December again. Saint nick might be long gone, but on the 10th of January the WOT is high on Christmas. Quite on time if I may say, my student house had its Christmas diner on the 25th of June last year. Which is literally the furthest date from Christmas.

Coincidentally, just a catapult shot away, Newton also had its Christmas dinner on the 10th. When I noticed this, I feared that some of WOT’s Mechanical engineers might be kidnapped and forced to go there instead. But luckily that was not case (with some exceptions). Even though I was sceptical about this date, our board assured us that the 10th was the right date because they ‘felt it’. Now, I have to admit (and I don’t do this often), were they right. We had a whopping 39(!!) WOTters show up for this fantastic candle lit dinner.

Preparation for the diner began two days beforehand with taking inventory, choosing recipes and of course the groceries. Then Friday morning the cooking began. I wasn’t there myself, but I can say with certainty that they cooked.
The appetizers (made possible by Norah and Erik) were savoury cupcakes with cheese, sun-dried-tomato and olive. Now whenever I hear ‘savoury’ and then something that’s not supposed to be savoury, like cupcakes, red flags go off in my head. I can confidently say that since I had these cupcakes those red flags have burned away. These cupcakes were a true delight, and I have plans to make them myself.

From here my light dimmed a bit, I may have had one to many glasses, or rather, bottles of wine. What I do remember very sharply are the next few dishes, and how great it all tased. The carrot-tomato soup, the Hachee with potatoes and red beet, and of course the apple crumble cake. Sometimes when I eat too much, I wonder whether all the food would be worth the extra weight. This is not one of those times. Hats off to Norah, Erik and Robin! The dishes they prepared were expertly made. Also, by pure coincidence, this was also the third homemade apple crumble cake I had in two weeks. Ranking these three is difficult since I made the other two myself, so I will have to call it a three-way pie.

Oh and we can’t forget the candles! As per WOT tradition, the candle holders are beuned just before the diner. Now all candle holders are special in their own way, but some were more special than others. Out of all of the candle holders, there are a lot of contenders for the nr 1 spot. But my personal favourite would have to be Nathan’s. Not because it was an original design, or because it had functionality, no in truth it’s a candle holder only it’s mother could love. That made burning the candle holder (which was just a block of wood with a hole in it), so much fun and memorable. Nathans attempts to save its pathetic creation just added fuel to the fire. And that’s why its nr 1… also because I forgot all the others.

All in all, it was a great Christmas diner. There was a lot of great food, deep conversations, flaming candle holders, and, of course, gezelligheid. Christmas is about sharing Joy with others. Whether you believe Joy goes through the stomach, or Joy is laughing with (or at) other people, or if you are an addict and think Joy is alcohol, there certainly was a lot of Joy. Here’s to next Christmas diner! As my great friend, and WOTter abroad Santiago would say, Happy Christmas, Happy New Year and Happy birthday!

Today we have learned a lot about the history of the Diever. But before we can dive into the story behind our most famous (but not most notorious) windmill we will cover an introduction about windmills in general.

In the lecture the rotor power coefficient (Cp) was touched upon and why some blade and rotor designs are more or less suitable for their designated purpose. Electricity generating windmills require less start-up torque to function and benefit from higher rotational speeds. This is why you see windmills with less blades that can utilise higher wind speeds. On the other hand water pumping windmills (WPW’s) require a much higher starting torque to lift the water column. Hence they employ more blades and a slower rotational speed, as you can see in the figure below.

Next we look into the shape of the blades. The most optimal blade shape is difficult to manufacture, so for budget friendly approaches, one is often limited to more simplistic designs. Such as the sails of the Crete or steel sheets based blades.

The goal of such water pumping windmill is to convert kinetic energy of the wind into gravitational energy by pumping a column of water up. This is possible by transmitting the rotational motion of the rotor to a vertical pumping motion. There are three main ways of transmission:

The most simple method involves a crankshaft. The crankshaft is connected to a wheel and the pumping rod as can be seen in the image below. A second method is using a four bar linkage. This method is most famously employed in pump-jacks, but is also very suitable for windmill transmittions. Finally, there is the pitman-arm transmittion. While this is a efficient aproach, the gears require lubrication and make the manufacturing and maintanance labor intensive.

Another important aspect of a windmill is the security. This is a mechanism that causes the windmill to turn out of the wind when it is storming and can also be subdivided into three main methods:

The first two methods use a helper vane that creates torque, such that the head of the windmill wants to turn. This is counteracted by the main vane that has more surface and thus keeps the head pointed towards the wind in normal conditions. One method is to add a spring to the main vane such that in stormy wheather it is pushed to the side and thus rotates the head out of the wind, this is used in the Oasis. Another method is to add a slanted mane vane/tail, such that pushing the tail to the side also requires it to be pushed upwards. With this design gravity replaces the role of the spring, this is used in the Kijito.

The last method is the tilting side-vane, which is used in both the Virya and the Diever on the WOT terrain. In this case the rotor is shifted sligthly off-axis (replacing the role of the helper vane). The main vane is also put off-axis to counteract the torque that is created by the rotor such that the head is turned into the wind direction. Is stormy weather the tail can tilt up, in this case the rotor wins the torque balance and turns the head out of the wind.

With this introduction in our heads we got into the developments that lead up to the newest version of the Diever in 2018. The story starts with another windmill that is designed at the WOT. The 12PU500 (a.k.a. Ghazipur) windmill was designed by Niek v.d. Ven and Willem Nijhof in 1979, when our association was in its first years. In this time period the Dutch goverment was willing to give subsidies in order to create water pumping windmills into an export product. With these subsidies and the TOOL foundation the 12PU500 windmill design got exported to multiple developing countries, there was even a factoy set up in Ghazipur, India. Eventually 3000 or more of these windmills were produced, but the project was seen as a total flop. Because a report came out stating that this windmill was too expensive and unreliable.

With this feedback Frans Brughuis drew up the first design of the 18PU450 (a.k.a. Diever) in 1987 at the WOT. These designs were published in 1990 and spread to developing countries, but we did not always hear back. With the information we did get back we figured that there are a couple dozens of Diever’s out there, mainly in Bolivia where a small setup was created that produced them.

But the development of the Diever did not end with this design. The first design had a slanted tail and a PVC pump. Later in 1993 the design was updated with a tilting side-vane and a brass pump. This design had an official opening with the former Dutch minister for Foreign Trade and Development Aid. In 2004 a new design was created with the four bar linkage transmission instead of the crankshaft in previous designs. In 2016 the head of the Diever on our terrain was replaced with the 2004 transmission and in 2018 the drawings of the new design were published. You can read more about the Diever and the reports on our website.

The technical report in 2018 included 3 versions:

• DA – a complete galvanisable version, without welds.
• DB – with the 2016 improvements, as built on the WOT terrain.
• DD – improved rotor and counterweight, this version was built in South Africa.

In 2018, the same year that the newest version was published, a South African farmer, Bennie, contacted us that he wanted to built a Diever windmill. So we sent him the drawings of the improved version (DD) and he got to work. When this version was built, some WOTters travelled to South Africa to watch it in its full glory. In the image below you can see the South African windmill with its four bar linkage pumping transmission.

There is another South African farmer that the WOT has cantact with and some WOTters have visited, namely Burgert Terblanche. He is called a water pump fanatic and has done several inventions. One of which is the HDPE pump, which can be more read about in this blogpost. The terrain of Burgert is full of small and large innovations on water pumps and windmills, such as a pumping rod with wood instead of a breakpin and the use of springs to dampen pumping strokes. He also thought of the “Forskop” that allows windmills to pump water up higher than their output. We also have some floating ball valves from him that we are testing on our terrain.

Hand drilling a well by hand is affordable, quick, and uses local resources. But in many areas, it’s not possible due to low water yield. A new method developed by Wolfgang Buchner addresses this issue, allowing hand-drilled wells to be installed in more locations.
Hand-drilled wells are usually small in diameter, which creates problems in soils that don’t allow water to flow easily, like clay or mica-rich soils. The small diameter limits the surface area through which water can enter, and the well’s filter screen often clogs with fine particles, leading to slow refilling; the well is pumped dry quickly.

In these soils, hand-dug wells have traditionally been used, as their larger diameter provides better flow. However, digging is a lot slower and dangerous work. Buchner’s method solves these issues and makes manual drilling feasible, even in challenging soils.
Here’s how it works: After drilling, a temporary casing—a pipe with large side slots and an open bottom—is installed. Water is pumped out, flushing fine particles that would otherwise clog the filter. Once the water runs clear, a permanent, slightly smaller casing with a filter is installed inside the temporary one. The temporary casing is then removed for reuse.

This approach cleans the surrounding soil of small particles and effectively increases the well’s diameter, combining the benefits of a small-diameter well with the water yield of a larger one. Best of both worlds!
To learn more about the method, have a look at the video:

We all know WOTters are the sportiest people in the world, but sometimes they need some extra exercise. This was achieved by fitting an old motor from a kid’s toy on an old rowing machine out of gym, connect to some batteries and we have renewable energy!

Because the motor from the kid’s toy is a three phase permanent magnet motor, it generates a 3 phase Alternating Current (AC) when rotated. This is very useful for high power motors such as in trains or big milling equipment, but not so much for small scale off-gird power. This is why the generator is connected to a ‘full bridge rectifier’, this takes the three phase AC input and converts it to Direct Current (DC). Cheers for AC/DC! The output DC of the rectifier is then connected to a lead-acid battery (also DC) and voilla; we can put muscle power into a battery!

Small off-grid systems often save solar energy in a battery and later convert that to 230 V AC. This can be done here too! So during the day one could use a solar panel and at night human power.

In the pictures above, the generator can be seen on the left. It is connected with gears and chain from a bike. This increases the rotational speed of the generator. Because the generated voltage is proportional to rotational speed, we can now generator higher voltages. On the right picture you can see two batteries in series (24 V). With higher voltages we can handle more power. With this setup, you could easily start a full sized diesel lorry (50 ton) if you row for a while!

Of course not everyone has an off-grid setup or a lorry with empty batteries. The energy in the battery can also be injected into the grid. Below is a picture of the generated power on the screen (every peak is someone pulling on the rower). To the left is a small solar converter that can inject DC into the national grid. This way we are powering an infinitesimal bit of the world!

This November we had our 4^th workingweekend of the year. And although it was cold and wintery outside ❄❄❄we were still kept warm by the all the work we put in projects. We prepaired the terrain for winter, fixed the PTB and the Diever and gave the Oasis a touch up.

Because of the upcoming winter the terrain needed to be prepaired. This meant that all the pipes needed to be cleared of water such that they do not break. WARNING PHYSICS SECTION: The reason this needed to be done is because of the very unique property of water that it expands if it freezes, you will not see this in almost all of the other substances. But why does water does this? When water (H2O) freezes it forms a hexagonal latice because of its distinct shape. This hexagonal latice takes up a lot of space, even more than the same amount of individual H2O molecules would. Conclusion: We need to close all the outside taps on the terrain every winter.

 
The Pump Testing Bench (a.k.a. PTB) has not been testing pumps for almost a year. Which of course is not what it is meant to do. Last summer the new tubes where ordered, but because of a mixup they did not have the right coating that would protect them against rust. So after a few weeks and multilple layers of paint they were finally ready to be put back in the PTB tower last weekend. They were also threaded and cut such that they have enough ground clearance such that a pump can be put under them.  Besides this, the motor that powers the PTB was stuk because of rust, but with a plumber’s wrench and a handy placement of a welding glove it was made unstuck again. In order to keep the PTB from being stuck we need to run the motor a few minutes every so often and we also started to design a cover that would protect it from rain.

At the start of the working weekend we noticed that the Diever was turning rather fast. Apparently the breaking pin broke, which (as its name says) is its purpose. But why do we inculde something a part with the purpose to break? You might ask. This is because we do not want the whole windmill to break itself in, for example; a storm. The breaking pin is meant to break the first in the system and is made to be easily replaced. This is why this job was easily done during the working weekend.

Our work on the Oasis began on Sunday with a relatively straightforward initial goal: to install a new pump. The first challenge was removing the T-shaped pipe connected to the windmill—a task we ultimately succeeded in with the help of a flamethrower. Once that was done, we moved on to installing the pump. This required fabricating a pipe to position the pump at the correct height within the water. However, we ran into a problem: we didn’t have the right thread maker available. As a result, the installation had to be postponed until some next Wednesday. In the meantime, we shifted focus to cleaning the windmill’s well in preparation for winter and to prevent the new pump from getting clogged. During the cleaning process, we discovered a family of frogs 🐸 living there. They were safely escorted to a new habitat.

As part of the cleaning effort, we decided to remove overgrown grass that was spilling into the well. While doing so, we uncovered gravel and brick edging around the Oasis base that had been hidden under a thick layer of grass. This led to a new goal: restoring the base of the windmill to its former glory. We carefully removed the gravel and bricks, cleaned them, and repositioned them. To enhance the restoration, we added bricks to the far side where they were missing and topped the base with fresh gravel. You can see the before and after in the images below.