Hydrofoil Project | EJNProjects

Human Powered Hydrofoil Project

ACADEMIC PROJECT - UNIVERSITY LEVEL (BEng Hons Mechanical Engineering) (COMPLETE)

This was done as an academic project for a design module, as part of studying a BEng degree in Mechanical Engineering at Plymouth University. The aim was to design a hydrofoil which was destined to be used in a 10km long race, competing alongside other watercraft of the same type. We were given a set of rules and regulations and were required to assemble a specification for our vehicle which would take these into account.

As this was a group project we allocated ourselves with different roles, my particular role in the project was design and development and I was responsible for developing the hydrofoil prototype that would end up being the final iteration that we would present at the conclusion of the project. SolidWorks computer aided design software was used extensively for creating and rendering the hydrofoil prototypes.

Individual Design Iteration 1

The project started with each team member putting some design ideas together and presenting them to our module leaders for review and feedback. My design idea was based on a twin hull design held together with a tubular aluminium space frame and utilized a stepless bicycle CVT transmission, this had a wide range of selectable gears and had a 380% range to have low speed and high torque for takeoff and high speed low torque for cruising speed. My design also made use of a belt and pulley drive system instead of a chain to eliminate the risk of corrosion damage.

Combined Design Iteration 1

As a group we decided to take the best features from all of our ideas and combine them into one design which we would develop and bring forward. This design made use of my stepless transmission and belt drive system and instead of having a propeller, it used a water jet for propulsion, I designed this to the specification of one of the other group members, as it was his idea. The design also had a single hull and stabilizer configuration which was taken from another group members previous individual design idea. With all of the groups feedback I set about designing hydrofoil 1.0.

Design Iteration 2

After some consultation as a group and finer calculations made using a performance prediction spreadsheet, design iteration 1 was refined and developed further, the changes included replacement of the water jet unit with a Kort nozzle, as it was a very complex component and required a greater RPM than the maximum value that was deliverable via pedal power and refinement of the hydrofoil hull and stabiliser units. One notable modification was made as a result of miscalculation, the power train system was designed to deliver a maximum RPM of 150 to the propeller when the actual desired RPM was 850. This problem sparked the idea of the Coaxial Intermediate Transmission System, or CITS, which was a RPM multiplier positioned between the output of the CVT transmission and propeller input shaft. The RPM was stepped up in two stages, using pulleys designed with a specific diameter and linked with rubber drive belts, this system was chosen to avoid meshing of metal gears in a potentially salty and sandy enviroment.

With the introduction of the CITS and boost in RPM, a decrease in torque was produced, this allowed for a redesign of the final drive system, enabling for lighter components to be used due to being exposed to 82% less torque in the low range of the CVT gearbox. Further modifications to this hydrofoil included a steering system enlisting rose joints and carbon fibre steering rods for precision handling and a lighter weight design and an automatic stability system that used an accelerator repurposed from a smartphone in order to control the pitch and roll of the hydrofoil.

Renders of hydrofoil design iteration 2