The Flanger

  The Flanger in action at Corvallis Open Streets in August 2017

The Flanger in action at Corvallis Open Streets in August 2017

I was originally asked to make the Flanger by the organizers of an event called Corvallis Open Streets, where a mile long section of city street was turned into a human-power festival. It is not something I would have come up with myself; the organizers of the event had seen and heard of the San Francisco-based human-powered carnival, “Cyclecide”, which has a lot of similar carnival rides. Unfortunately, Cyclecide is not well documented on the internet that I have found, but they periodically do a traveling show, so keep an ear out; they’re really cool. They have various carousels and rotary swing rides, but I think the coolest ride they have is a three-person human-powered ferris wheel that goes scary fast. If it gets going fast enough, the lightest rider’s seat will flip over and inscribe small circles in the larger ferris wheel. When I met them, the people of Cyclecide were preparing for a three-week journey down the Willamette on an armada of barges, one of which had the ferris wheel on it. Another of their barges served as the living space, and also had an upper deck which could be used as a performance stage at various towns they stopped at along the way.

  Cyclecide’s ferris wheel barge, docked in Salem

Cyclecide’s ferris wheel barge, docked in Salem

When the organizers of Open Streets approached me with the idea, I was a little skeptical, as my passion tends to lie with things that have some practical component as well as cool factor. My first calling, for instance, is building bike trailers and other wheeled conveyances that allow things to be done that would otherwise be unfeasible. I started building bike trailers for the Corvallis bike polo club about eight years ago, because we had all these 12’ boards that we needed to haul to the court every week. We had limited access to vehicles that would work for the job, and also we had a pretty disdainful attitude toward the idea of using cars to support our bike polo habit, so we built a lot of trailers for hauling the lumber, our lights, sound system, balls, goals, mallets and extra bikes. One guy in particular (who is now my roommate, coincidentally), Carl Gurney, made a few trailers out of old bike frames, brazing them together into a really frickin genius bike trailer (the trailer’s wheels bolt into the dropouts of the bikes that it’s made from). Also, our leader at the time, Eilif Knutson had a three-wheeled contraption he had built in high school called “The Mantis” that would haul all the boards on lumber racks beneath the seat. It was very mind-blowing to me, as it was sort of my introduction to the larger cycling community.

  Fun times with bike trailers, Eilif Knutson hauling pallets to set up a quarter-pipe in the heyday of fixed-gear freestyle. The trailer is made from old bike frames cut and brazed together by Carl Gurney.

Fun times with bike trailers, Eilif Knutson hauling pallets to set up a quarter-pipe in the heyday of fixed-gear freestyle. The trailer is made from old bike frames cut and brazed together by Carl Gurney.

I have lost a lot of confidence lately in what I believe in and have trouble figuring out how to make a positive difference in the world. The way I’ve come to view the Flanger is as a gift to the community in the hope that other people can have their minds blown how mine has been blown by people doing cool things with human power. I want lots of cool people to join the bike/human power community, so I hope seeing a cool and unusual human-powered carnival ride like the Flanger makes people want to get involved and contribute their own cool stuff.

The Flanger began as a set of rough sketches in my notebook, followed a few dozen insomnia-fueled “working drawings” made over the next few months. I had been given the general instructions of, “Make one like Cyclecide’s got” from my customers and after dreaming and scheming for a while, came up with the idea of having a two person swing ride, where the riders hang from a boom that swings around and their pedaling provides the propulsion to make it swing.

Flanger Schematics.JPG

I bought material and started by building the base/tower section ,which is just a sturdy, stable pintle that the upper boom rotates on. Originally, I used a 3” round tube as the center frame member, and got well into the project before realizing that it wasn’t going to be strong enough. The center tube supports any imbalance in weight between the two riders as a bending load and horrible images of what would happen if it were to crumple kept running through my head. After moaning a bit about having to backtrack, I went back to the drawing board and redesigned the frame and the upper hub to work with a 5” diameter tube. The frame is comprised of nine straight pieces that bolt together into a space frame.

  Testing the structural integrity of the Flanger’s frame before deciding that I needed to redesign it with a larger center tube.

Testing the structural integrity of the Flanger’s frame before deciding that I needed to redesign it with a larger center tube.

The upper, rotating assembly rides on the center tube using a large tapered roller bearing at the top and plastic bushing blocks lower down. The booms bolt onto the hub and are supported with tension cables. One improvement I want to make is to replace the cables with tubular members.

  The upper tapered roller bearing, which supports the static thrust load of the weight of the riders and boom.

The upper tapered roller bearing, which supports the static thrust load of the weight of the riders and boom.

The propulsion system stumped me for a while as I barked up the tree of mechanical torque transmission from the bicycles to center hub. The difficulty I was having was figuring out how to arrange my imagined shafts and chains to account for the fact that bikes swing out on their hangers as the boom begins to speed up. Hydraulic drive is something that has intrigued me for a while as a possible way to run a front wheel drive on a bicycle, so I decided to power the Flanger through hydraulic transmission in order to learn how to work with hydraulic systems. People have pointed out that hydraulic transmission is too lossy for human power, but since the Flanger operates at relatively low RPM but requires a huge amount of driving torque, the fluid-friction loss is actually not very bad.

  The hydrualic pump, driven off the rear wheel of one of the bikes   

The hydrualic pump, driven off the rear wheel of one of the bikes
 

The Flanger remains a work in progress. In addition to making it more fun for a greater variety of people, there are several improvements I would like to make to remedy possible weak points in the design. A week before the debut of the Flanger, a carnival ride broke at the Ohio State Fair, killing a young man and injuring a number of others. People kept asking me in the week leading up to Open Streets, “Didja hear about that carnival ride collapse in Ohio?” Ultimately, I think I have a healthy fear of a catastrophic failure with the Flanger. I have asked the people I trust the most with engineering intelligence for their approval, and invite anyone who sees a potential failure point to please tell me.

To this point, the Flanger is my magnum opus (thank you Charlotte Spider), my defining creation. I feel drawn on though, by bigger, and as yet unimagined creations to inspire people and hopefully expanding people’s idea of ways that human power can be used.

Some of my next projects are:

  • A fleet of bike-pulled sleeper trailers for people who need mobile shelter.

  • A bike trailer for the county health department to haul water and medical supplies into the woods.

  • An eccentric-wheeled “bouncer” scooter for my friend Laura who is a bigtime kinetic sculpture racer. She’s got a couple of these bouncers already, but they’re falling apart so I’m trying to design a more durable one.

  • Restoring an old kinetic sculpture called “The Counterfeit Cadillac” that looks exactly like a 1963 cadillac, but is actually a four person human powered vehicle. It’s also amphibious

Counterfeit Cadillac.jpg