Propeller driven bicycle


This is a neat bike.

MIT student Damon Vander Lind wheels his human-powered, propeller-driven 300-rpm tricycle out for a test drive.

Mounting generator on bike

plate, covered measurement is 1 & 11/32”. That's between the two top mounting bolts.

Okay, here’s what the output of the pedal system looks like.

I think it will be easy to make a direct drive system. I suppose making a plate with holes matching the pedal system (right), then having the motor mounted on standoffs that are mounted on the same plate.

Add some sort of coupler to connect the two shafts. I guess I’ll see if a coupler is available for the two shaft sizes. If not, I suppose I’ll have to make one. I don’t have a lathe but may buy one if I need to make this sort of thing often.

I wonder if it’s easier to add an A-axis to my mill? Any comments on that?

motor plate

Here’s what the generator looks like. As you can see it has a face plate that has three mounting holes.

It also has a sprocket which I will remove. I guess I need to measure that shaft.

I need to get or make some standoffs to connect this motor to the mounting plate.

Are they available or do people make those? I suppose some 1/4″ threaded rod would do. Hmm, that sounds like a great inexpensive way to mount it. I’ll give that a whirl unless somebody gives me a better idea.

generator face plate

So the mounting plate will have 6 holes. Three for the pedal output, three for the generator. The generator will be mounted on a standoff and a direct drive coupler added. There will of course be a hole in the plate in the middle for the drive shaft.

I was able to cut the part out on my CNC mill. I used the Phlatboyz plugin to generate the g-code.

The outer holes match the generator perfectly. I will send this over to Sanjay and see if it fits his bicycle thingy.

Interestingly, the first time I generated the g-code, the straight lines at the perimeter of the piece came out as curves. I right clicked each line and expanded or exploded (can’t remember).


After generating the g-code again it seemed to behave. I find that with the phlatboyz plugin you can’t have any components, grouping and such.

I find it really important to verify the g-code before bothering to load it on my mill.

NCPlot has proven to be very nice for this. It shows the tool path in great detail and you can pan and rotate around. You can even “play” the file and see the tool path motion at whatever speed you choose.

Human Power vs. Hamster Power

I’ve been working on a human power for kinetic art so a post on hamster power in the Ottawa Robotics online community drew my attention.

According to the post, a hamster can produce .15 Watts peaking at .45. That’s more than I expected. Humans are around 75 Watts so that means it would take 500 hamsters to match a human at that rate. Hey wait… if a hamster is 3-5 ounces (I googled it), then it’s the expected wattage. (At 4 ounces they are a quarter pound so a 120lb human should be equivalent to 480 hamsters).

I have had the occasional thought about trying to get Squirrels to run on hamster wheels. It’s not much power but at least the energy source is your garbage which is waste anyway (okay, they may be eating your neighbors’ garbage too. And I once saw a Squirrel eating a nut from a tree). They use some of the calories from your garbage to spread the rest of your garbage around your yard.

Perhaps they could be coaxed into using some of the left-over calories from your garbage to run a wheel. 🙂