Jump to: navigation, search

Interested People

  • James
  • Ray
  • Rick Lellinger (DGPS system)
  • Mark (peripherally involved with laser perimeter system)
  • you, once you add your name, please


The Mothership is a control station, icon and and transportation device. Here's a mockup from the Proposal.

Current designs

Current designs(as under construction at the boxshop now!)

Iso.gif Top.gif Drivetrain-diagram.gif

To do

Dammit! just noticed on 10/2011 that none of this is checked off, we'll never be done in time!!! Actually, stay tuned for amphibious adventures of the Mothership!


  • most of structure is cut, ready to weld
  • wheel bearing mounting plates
  • mounts for shafts, pedals, brakes
  • mounting method for crossmember
  • mounting method for front axle that allows caster angle adjustment
  • seats- will be determined once we get pedals and wheels on
  • steering- linkage not designed yet- depends on seat setup whether we can use steering wheel or handlebars
  • antenna mast or superstructure
  • boxes for geek stuff


  • cut special ring gears
  • cranks, bottom bracket, pedals
    • How to attach bottom bracket? Maybe cut bottom bracket pieces off scrap frames?
    • Cranks need to have removable ring gears so we can attach our custom ones
  • freewheels and adaptors
    • 2 final drive freewheels: found wide range (14t-34t)freewheels at box dog bikes for $20 ea.
      • Needs special derailler- maybe make our own setup for final drive?
      • If we could find something like this cheap, would be awesome to use it for all 6 freewheels
    • 4 pedalar freewheels: Specd for 13t-27t; not much room to make the range any smaller
    • adaptors- wheel support requires us to have 3/4" shaft, so might as well go with 3/4" all around
  • bearings- ray will go to Bearing Engineering and probably get what we need there
  • other gears- might cut along with ring gears
    • rear drive- 2 53t ring gears
    • rear pedaler transfer chains- 2 pairs of same sized gears
    • attachment method to shaft?
  • idler wheel thingeys- 4 of them
  • chain- lots! is stuff available on rolls as strong and will it work with derailleurs?
  • brakes
    • motorcycle calipers- would be good to find bike with dual front brake system at bikeyard or fremont cycle savage
    • rotors- would be good to use aluminum for weight- will it gum up brake pads and not work?
    • rotor to shaft mounting method
  • derailers, cable, shifters


  • an iconic art-car shell
  • vehicle lighting
  • 6 70 lb orbs
  • 6 sets of 20 lb batteries (the second set of batteries)
  • laptop computer and other computer parts
  • DGPS beacon
  • (maybe) generator to charge batteries and/or drive the Mothership
  • (maybe) many flags and ribbon to mark off our performance space
  • Laser perimeter scanner


Laser Beam Perimeter

Marc Hertlein is getting a 20mw green laser, spinning mirror, and plexiglass cylinder. We'll mount it on top of a 15-20' pole. There's still issues about how we'll do the pole, maybe aluminum or fiberglass with wire stays.

Here's a web link to a site that calculates laser parameters and hazards:
5mW is the threshold (for green) from 3a to 3b lasers, but even with 20mW the light beam can be quite safe, because of the divergence, distance and spinning mirrors involved.

what follows is older stuff

Laser Perimeter Ideas: On drawing a perimeter of 100’ radius using lasers mounted on a tall mast (for nighttime shows)...

A laser on its own only makes one single bright point. In order to draw a line with it (a circular line for our perimeter), you need to somehow spread that point out. We need to cover about 628 linear feet of perimeter, and when you spread the laser out it gets dimmer. So we could use one very bright laser, or we could use a number of lower-power lasers. 5mW green lasers are fairly easy to buy for a reasonable price (~$50 each) and are fairly safe around peoples’ eyes, so that’s probably the upper bound for power we’d want to use. As just a guess, we’ll probably need 6-8 lasers to get enough brightness; each could scan out 40-60 degree section of the circle.

Either way, we need a way of spreading out the beam. There’s three proposed ways of doing this:


1. Scanning, using a set of spinning mirrors

This is the way grocery-store barcode scanners spread their beam. Basically you’ve got a polygon (hexagon or octagon usually), where the mirrors are on the sides of the polygon. In most cases the polygon mirror is a single piece of glass with polished facets that’s been metalized to make the reflective surfaces of the mirrors. The polygon is mounted on a bearing so it can spin, and a motor is connected to that. When the polygon mirror is spinning, if you point a laser at the side of it the mirror aims the beam at a range of angles, spreading that point out into a line in a series of scans.


  • You get a very clean, well-controlled line output, and one spinning prism could be used to scan all 6-8 lasers (basically put lasers around the prism, each one hitting a facet of the mirror at any given time).
  • A very slow scan can make a bright slow-moving point on the ground. Scanning it fast or spreading it optically might make the laser dimmer.


  • Moving parts are always iffy on the playa (dust getting in the bearings, motor).
  • Since the mirrors are first-surface, they are delicate and not REALLY easy to clean. It might be good to build a transparent housing around the whole thing to keep dust out... which could be a bit of a pain.


2. Spin the lasers

Instead of keeping the lasers stationary and reflecting the beams off a set of moving mirrors, mount the lasers on a spinning wheel. This would just require building a mount for the multiple lasers that included a bearing and interface to a motor.


  • Should be very simple to build


  • Getting power to the lasers gets a little trickier when they’re spinning.


3. Optical spreading, using cylindrical optics

The idea here is to use a lens that only expands the beam in one dimension. The type of lens that will do this is cylindrical.


  • No moving parts


  • It’s probably difficult to find a cylindrical lens that spreads the beam to an angle of 60 degrees (which is probably what’s required). If a single lens can’t do this, we’d need some kind of multiple lens and/or mirror assembly, which gets complicated

Mothership Design

Some suggestions from a Burning Bikes Tribe discussion

you should build atop a quadracycle, rather than having to tow it. Were you in Illumination Village last year? I used this one to haul the entire grid for the village. 4 50amp works boxes, ~1000 feet of coiled 6/3 cables with twist lock plugs. The entire load must've weighed over 500 pounds. The Quad was geared low enough to make it easy, and with better load balancing, it'd keep the load stable.

Here's a link to a gallery of images for reference:

The key to building one? Rhoades, the original manufacturer, fabricates and sells adapters that will allow you to mount a standard BMX freewheel or old school threaded 6-7 speed freewheel to a keyed shaft in either 5/8 or 3/4 diameter. This allows you to use standard bicycle chain and gears to build your drive train, and it uses a clever trick to create independant drive wheels.

Another suggestion

The Rhoades cars are a great start - but if you can't get that I can also provide an already built sociable tandem (like what you sketched) for you to use as a tow vehicle 'template' to build your own sociable tandem. I live in Lower Haight and there is one in my garage ready to roll, pics in my profile and BRC rickshaws tribe.

I am also going to be doing a 'build your own sociable tandem' demo at the upcoming Maker's Faire (with help from friends - interested?)....

Good luck - this art project is gorgeous!

Another idea... Here is the design patent, for all you devious reverse engineers-

A helpful contact. This is a message to Lee on Tribe

just thought I'd drop you my number and a link to some fun stuff we've built that pedals. I'm in Humboldt County, but have friends in Oakland who have a good understanding of things that pedal if you need more local help. They also have a 6000 square foot warehouse filled with welders and other tools.

I am also a Kinetic racer, like Elliot, so I can give you some EASY ways to modify bike parts to make them do what you want. Go-cart and motorcycle parts are also great! I was on a machine that was pedaled by 6 people and weighed in at 2000 lbs. We had low enough gears to climb a sand dune, sometimes pedaling with our hands to keep from flipping over backwards.

Anyway... here's a link to our crew:

And my numbers: Home: 707-826-0117 cell: 707-845-4294 feel free to call with any questions, if I don't have an answer I'm sure i can get one!

Scotty C.