Why “Eta Prime”?

Sometimes we name our vehicles on a whim or just because it sounds cool. This time there’s a bit more to it than that. Eta Prime promises to be our best-ever speedbike, and indeed one of the fastest bikes in the world, so we chose its name carefully to acknowledge the origins of the design and speak to our motivations for doing this project.

One of several candidate visual designs for the external shell of Eta Prime.

One of several candidate visual designs for the external shell of Eta Prime.

We wanted to use “Eta” in the name for two reasons. First, it’s an acknowledgement of AeroVelo‘s achievements with the original Eta speedbike. They created an excellent foundation for this new vehicle, and every success we have with Eta Prime is theirs to share. Second, “Eta” – properly written as the Greek letter η – is the symbol for efficiency throughout the engineering world; that’s why AeroVelo chose the name to begin with. Achieving high speeds on limited power is all about efficiency.

In engineering and mathematics, quantities are often manipulated through many steps of calculation until they’ve been transformed into something else, but still related to the original. This change is denoted by the “prime” symbol, which looks like an apostrophe. In particular, a derivative of something (it’s slope function, in simple terms) is often indicated by a prime. For example, a function x would have a derivative x′ (read as x-prime). We’re bringing new ideas and perspectives to the Eta design, so we’re calling the result Eta Prime. It’ll have have many differences, but this new speedbike will still be a derivation of the original.

η  →  η′

Stay tuned for more updates as we re-design, build, and test this new vehicle!

Calvin Moes, HPVDT Captain

“New” Metalworking Lathe

Even the best designs are useless if you can’t build them, so we place a major focus on finding the right tools for every task we need to accomplish. Eta Prime involves a lot of custom rotating components. To make these components, we needed a lathe that could handle the size of our parts while maintaining a high level of accuracy. Thanks to our faculty advisor Prof. Nogami and the Department of Materials Science and Engineering, we now have what we need.

 

Despite it's worn appearance, this lathe functions very well.

Despite it’s worn appearance, this lathe functions very well.

Deep in the Engineering quadrant of U of T’s downtown campus, in a building few even know to exist, our “new” lathe waited to be found. Estimated to be at least 25 years old, this machine has been idle for much of that time – but no longer! Like many old-but-well-built tools, this lathe works great despite its worn appearance.

For those of you who don't do this sort of thing, a lathe functions by spinning the workpiece - typically a bar of metal - while the operator uses several adjustment knobs to slowly move a cutting tool against it.

For those of you who don’t do this sort of thing, a lathe functions by spinning the workpiece – typically a bar of metal – while the operator uses several adjustment knobs to slowly move a cutting tool against it. Here, you can seen chips of aluminum being cut off of a cylindrical bar by the tool on the left.

Over the next weeks and months, our Mechanical Systems Group will be producing a variety of bearing shells, spindles, and hub components for Eta Prime. Check back soon for more info!

Calvin Moes, Team Captain

Disc Wheel Construction

Momin, one of our first-year members, prepares the carbon fabric panels for the disc wheels.

Momin preparing the carbon fabric panels for the disc wheels.

Two of the most demanding structures on Eta Prime are the wheels. Beyond just holding the weight of the rider, the wheels have to withstand impact loading from bumps, pressure loads from the highly-inflated tires, braking and acceleration torques, and immense side loads from the occasional crosswind gust. Add to that list the requirements of a smooth aerodynamic surface and tight tolerances to fit alongside everything else in the vehicle, and you have a very challenging design problem.

Evan lays epoxied carbon fabric panels into the disc face mold.

To meet this challenge, we’re building an advanced composite disc wheel. The discs for the wheels are made with TeXtreme® spread tow fabric to achieve the best strength- and stiffness-to-weight, with local reinforcements of TeXtreme® fabric and unidirectional carbon fibre for improved stiffness and durability. These materials are molded together with a structural foam core to produce a stiff and light disc wheel. It’s a time-consuming process to prep the materials and mold, but this is what it takes to compete with the fastest teams in the world.

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Rohacell® core panels for the disc wheels are shaped on our in-house CNC router to ensure the discs are as flat as possible.

Disc wheel components ready for assembly.

Disc wheel components ready for assembly.

The rims have just arrived from Velocity USA, and our Mechanical Design Group has nearly finished constructing the hubs. Check back soon to see the next steps of our wheel construction process!

Calvin Moes, Team http://sildenafilpharma.com/ Captain

Aerodynamic Fairing Molds

Speedbikes go fast for a variety of reasons, but the most important aspect of a speedbike’s performance is aerodynamic drag. That’s why the fairing is so critical; the air must flow smoothly around the bike to minimize drag. It’s a delicate balance between a variety of competing factors, but – thanks to our partner team AeroVelo – we’ve got the best design there is.

One half of the fairing mold set.

One half of the buying cialis without a prescription Eta fairing mold set.

Todd Reichert and Trefor Evans spent much of 2014 trying to create the best possible aerodynamic shape. They found an optimal balance of vehicle geometry and rider ergonomics that allowed an awesome fairing to exist around the vehicle while still allowing the rider to be comfortable and efficient. Their design is quite literally a work of art. We’re using the same fairing shape for two reasons. First, we don’t have the time and personnel this summer to re-optimize the fairing for a slight improvement. Second, there’s not much to be gained for a team that operates like HPVDT; the fairing fits (or can be readily made to fit) a variety of our riders, and most of what could be improved would detract from this. It’s important to us that everyone on the team eventually has the opportunity to ride the vehicles we produce.

Another advantage of keeping the same shape is that the mold set (also called tooling within the composites industry) for the fairing has already been made. This saves us a huge amount of time, effort, and materials. We’ve just brought in the molds from AeroVelo’s storage facility. Check back soon to see how we’re preparing materials to build the fairing!

Calvin Moes, HPVDT Captain

First Steps on Two New Projects

As the team wraps up construction and testing of our ASME HPVC entry for this year, I’ve been planning out HPVDT’s next projects. We had a General Meeting yesterday to get things going, and now it’s official: our next projects are a new speedbike and – for the first time ever – a human-powered submarine!

Our new speedbike will be similar to AeroVelo’s Eta, which many members of HPVDT helped to build over the summer of 2014. However, not all of its systems and components will be the same. Some of the design changes being made are a more accessible fairing construction, improvements to the frame geometry and stiffness, and (as part of an ongoing partnership with AeroVelo) new wheels. We’re also investigating some entirely new systems, such as landing gear, real-time measurement of tire temperatures to provide warning prior to failure, and a means of cancelling-out the motion of the rider’s legs during high-speed sprints. The plan is to have the new bike constructed by August to allow for testing and troubleshooting before the World Human-Powered Speed Challenge in September.

The Eta speedbike, designed and built by HPVDT's partner team AeroVelo, will serve as a baseline for our new bicycle.

The Eta speedbike, designed and built by HPVDT’s partner team AeroVelo, will serve as a baseline for our new bicycle.

We’ve built bicycles, tricycles, an ornithopter and a helicopter. Once again it’s time for something new: a human-powered submarine. We’re still working out the details, but the goal is to build something that’s agile, fun, safe, and fast – hopefully fast enough to break the current speed record of 7.282 knots. It’s an exciting time, since none of us have ever designed anything like this. We’ll be looking at new aspects of performance and efficiency, as well as a whole bunch of new safety concerns. I am confident that we’ll succeed; every student on HPVDT is smart, motivated, and above all competent in engineering design.

 

The current world record of 7.282 knots (3.75 m/s) is held by Omer 8, a submarine designed, built, and operated by students from  École de technologie supérieure (ETS) in Motreal, Quebec.

The current world record of 7.282 knots (3.75 m/s) is held by Omer 8, a submarine designed, built, and operated by students from École de technologie supérieure (ETS) in Motreal, Quebec.

Check back regularly for more updates on our progress for both of these projects!

Calvin Moes, HPVDT website Captain