We Made an OCTOPUS Wind Turbine!

We build inventions designed by kids & 11-year-old Summer challenged us to build her idea for an octopus-shaped wind turbine. Here's how we brought her idea to life!

Our turbine was assembled from steel, plywood, resin, copper, neodymium magnets and a range of electronic components. The basic design of our wind turbine was inspired by the brilliant Wind Turbine Recipe Book written by Hugh Piggott:

https://scoraigwind.co.uk/a-wind-turbine-recipe-book/

In it are plans for 6 different sizes of wind turbine. Including; how to carve wooden blades, weld the wind turbine frame and wind the copper coils for 12, 24 and 48-volt battery systems. Hugh's turbine design furls itself automatically to protect against high windspeeds.

An Octopus naturally has more tentacles than a typical wind turbine has blades, however an 8-bladed wind turbine should start spinning at lower wind speeds than a traditional 3-bladed design - although won't be able to spin as fast.

We created the blades for our Octopus turbine from 6 inch (150mm) PVC soil pipe, as it allowed us to easily create a curved tentacle shape that was readily shaped to catch the wind. In our case it was a trade-off between blade aerodynamics and octopus aesthetics!

Many people have created wind turbine bladed from PVC pipe, however an important consideration when building a wind turbine for prolonged use, is that PVC pipe does degrade over time when exposed to UV light. In our case our blades were very much a prototype, so we were less concerned about longevity over months and years of operation.

The basic blade making process we followed was as follows:

• Mark up PVC pipe based on chosen blade shape (use a template or design a custom blade shape)
• Cut PVC pipes into blade shapes (we found a skinny disc on a angle grinder worked well
• Sand the edges and surfaces of the blades to make them smooth, paying particular attention to the leading edge (the blade edge that spins into the wind first).
• Reinforce blades along their length using steel of aluminium strapping.
• Attach blades to a plywood rotor assembly with appropriate mounting holes for the chosen generator design.
• Balance the blades so they spinning evenly (procedure outlined in the book).

The basic steel structure of our octopus turbine followed The Wind Turbine Recipe book's 1800mm diameter turbine plans. It uses commonly available standard steel sizes.

We used scaffold poles for the main mounting pole for our turbine, along with a temporary steel base support. If we were to install the turbine permanently we would create a concrete foundation.

We attached a lever or "gin pole" to the wind turbine, so that we could easily lift it up and down.

We were kindly donated our generator from the University of Exeter, but the Wind Turbine Recipe book explains how to build one from scratch using enamelled copper wire and neodymium magnets set in resin. Or alternatively Hugh Piggott has a simpler design using cheaper, hardier ferrite magnets that do not corrode as readily as rare earth magnets. You can find our more about this book here: https://scoraigwind.co.uk/2014/06/ebook-plans-for-2f-turbine-now-finally-published/

We haven't included all the steps here that are required to build your own wind turbine, as the Wind Turbine Recipe Book is by far the best resource for all the detailed information you need, and the finer details of the basic turbine design we utilised are all available in there. However if you want to find out more about how we added our own octopus upgrades to Hugh's design than make sure you watch the video above!

We used our turbine to charge a 24V lead acid battery bank, via a rectifier; to convert the turbine's AC output to a DC supply to our batteries. We then converted our stored battery energy to 240V AC via an inverter, to power a 3D printer and a 240V crepe maker - to make some octopus-shaped pancakes!