Intro: TFcD Airborne Wind Turbine
This instructable is made for documenting an assignment made by students of the Technical University Delft for the course Technology for Concept Design. It will consist of steps for a quick prototype.
The technology we chose is an airborne wind turbine. Because of the short time in which the prototype was made it unfortunately has not become airborne but the basics are there.
It starts with creating a generator, we used an old pc case fan as this has all we need for a wind powered generator. We actually had to use several as a few where broken in the process of taking them apart. It took several old case fans before we got one that could be disassembled easily. They are all constructed somewhat differently and are not all suited to be converted into a small generator.
After the case fan was converted we had to create a simple construction to support the fan. This was made using materials u can easily find in your own home.
We used a separate fan to create the airflow to test how it would behave when it would be airborne (almost no wind outside on the day of testing). Also, the was idea to made it airborne was simply attaching helium balloons but this would not fit withing our (student) budget. The helium was more expensive then we had expected.
Step 1: Converting (destroying) a Case Fan
We have used four different case fans before we got one that could be converted.
We can explain what we did or just redirect you to the instructable we used for this part, we choose to do the latter one. Don't get fooled by the title, it will probably take you more then 10 minutes if it is your first time.
Step 2: Attach to Base
Now that we had a working generator we created an fast construction to attach the fan to a toilet roll tube. We attached a few parts of a skewer to the backside of the fan and push one through the tube, used a small knife to create two small holes so the skewer went through without crushing the tube. Then we used tape to connect the skewers. It is far from durable but for the simple prototype it was good enough.
Step 3: Tail
To create some balance, the fan is relatively heavy, and to make sure the construction will face the wind we added a long tail.
It was made out of thick paper, one horizontal part en two vertical parts to increase the stiffness. It is all glued together. The small part on the bottom of the horizontal tail part was made because we forgot to add a folding edge we could use to glue it to the tube. The total length is 25cm and was inserted 4 cm into the tube. The horizontal part was aligned with the skewers for (expected) stability and then glued to the inside of the tube.
Step 4: Testing
The entire construction was 78 grams, could be lifted by a few helium balloons. We attached a string on both ends of a skewer and found out that when attached to the front skewer the construction got tail heavy and rear skewer made it front heavy. We estimated where we would have to add a third skewer to make it balanced and we just missed it. Sill a bit front heavy but when we put it in the airflow the tail construction made it level out, also the fan was spinning so it was a win win.
We could not add the helium balloons to test it outside but and we would advise to create a construction to prevent the string from touching the blades but for us this was good enough for validating the prototype.