## Let's make valveless turbine bicycles!

Moderator: Mike Everman

hagent
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### water and PJ

Hey Eric,

I think you just created a great industrial humidifier! Should be good for a large building.

On second thought maybe we could use it as a snow machine? Seriously if you use liquid water at 0 deg C or just above it should get thrown out and turn in to snow in the cold evening air! Plus you would be in the mountians. Hey you live in the mountains! you could try it for us

Cheers,
Hagen Tannberg

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### Valveless Bicycle

I had a hunch when I first saw this but it wasn't until today that I finally asked my Dynamics professor to confirm it--by mounting the pulse-jet like this on the wheel, the bike will accelerate no more than 1/2 as fast as the same motor mounted conventionally (on the frame pointing back).

*edit* I'm not trying to put the idea down, I think you made a really incredible pulse-jet, certainly something I haven't seen before, but I did think you'd want to know this

Mike Everman
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### bike turbine

Sorry, but no. Must be a breakdown in communication somewhere. The bike tire is merely an idler. The drive wheel connected to this jet's axle is only 2" in diameter, driving the outside of the tire, so schematically can be considered driving the ground with a wheel that is of 1" radius.

If my motor puts out 4 lb at a radius of 8", I will be seeing 32 lb of force at the road. The design speed is 25mph, so I'm getting 32 in-lb of torque at 4,200 rpm.

I'll likely start with a wheel of 4" so the rpm's are down at a more sane level, and determine if it is anemic or fun. Either way will be fun.

I'll have to get a Brain doll to put on the handlebars. ;-)

Here's the current state of the assembly... one shows the equivalent mass in thick washers for rough balance set on top.
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pgup
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### Hero's turdine

What ever happened to the Hero's turbine of this thread?

Was it ever tested?

Did it ever work?

Mike Everman
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I just put some fuel through it as shown (not spinning!). That's not the intended intake, but the beginnings of a plenum around the 1" intake I haven't made yet. I just wanted to push some fuel. Combustion happened way down the tailpipe, but I made some noise with it.
I'm re-doing the hub. It's wimpy as it is.
Got to spin this one up soon, even though I've re-designed it infinite times.
Mike
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Mark 42
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I think attaching a one pound propane cylinder in the middle
and letting it take of across the desert like a big pinwheel
would be an absolute gas!

Or turn it horizontal, put some blades around the outside
that are like a fan (sort of, actually more like a turbine
engine's bypass section)... and make a big, dangerous,
self powered, super hot, heavy, hazardous frisbee!

I like the innovative concept. I don't think it'll ever get
45 MPG, but it will be a riot to see it work.

I wonder if it'd make a good power source for a pump.
Maybe a strange compressor for a new type of turbine.

pgup
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### Hero's turbine

Mike Everman wrote:I just put some fuel through it as shown (not spinning!). ...
I'm re-doing the hub. It's wimpy as it is.
Got to spin this one up soon, even though I've re-designed it infinite times.
I think at one time you said you were going to put a torque wrench on it...Even if you never actually spin it up (or rotate it at all), it would shed some interesting light on the issue of assymetric thrust production with high-speed inlet flow, which is something I think you've said or implied you're counting on for this engine to work well (since normal thrust production is usu. a 40/60 split, inlet to outlet)?

With a well-damped torque wrench setup, plus a gas-powered leaf blower (which is throttle-able), and a simple u-tube manometer to measure leaf blower velocity you could generate some very interesting and useful data, before going to the effort to supply fuel to a rotating engine, or solving additional structural problems.

It would be interesting to see a graph of output torque versus inlet forced-air velocity, for a series of constant fuel flows.

pgup

Mike Everman
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Hi PGUP,
I just posted the air velocity curve for my leaf blower in the tools forum saturday, so yes, this is what I will be doing.
For this first simple proof of concept motor, I'll just be tuning the intake for best running 20-25mph at the bike. As you say, the first step is reliable intake ram air, and torque feedback at a minimum. Kind of difficult to adjust intake length while spinning!

Ideally, there will be no thrust split when it is run in this mode. The intake thrust will be beat back and hot gas will not escape. I am scavenging some of the drag that would otherwise be purely parasitic.

How ram air affects the intake is the interesting part. It will be a shorter intake, as it will have cool air in it more of the time, so the average acoustic temp and therefore thermo-acoustic length will be longer than an otherwise static motor.
Fun stuff.

I keep wanting to throw it out and start over, because I've designed far better configurations before and since this build, but alas, if the end of the story is "but it works", then how ugly it is becomes somewhat moot!
Mike
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pgup
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How true!

It's what you can learn from it that counts...you can build the "pretty one" later.

You said your gage topped out at 130 MPH (~=191 FPS). I have found the following formula reasonably accurate for first approximation purposes, for measuring ambient temp airflows up to about 250 MPH:

Where velocity is in FPS and Head is in inches W.C.

SO, you could build yourself a simple u-tube manometer to make these measurements yourself and cover the range from 130 MPH to 215 MPH.

For instance, 215 MPH = ~ 315 FPS. Using the above formula (solving for head), the pressure differential is about 22 inches water column. Not a very big manometer...

Mike Everman
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I like it! Thanks.
Mike
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Eric
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I think you should make something penny farthing sized, maybe a 50 pound U shaped engine, combustion chamber towards the middle, maybe a ramjet on the other side to provide ballance / additional thrust for when the wheel inevitably gets up to 300 mph :D

Eric

Talking like a pirate does not qualify as experience, this should be common sense, as pirates have little real life experience in anything other than smelling bad, and contracting venereal diseases

Mike Everman
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Either way, It's a way to get around Burning Man. ;-)
Mike
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### whirly progress

I installed the adjustable intake I posted in the tools section. Sealing is with ceramic rope. Itchy stuff.
Torque wrench is mounted.
I need some additional securing of the static part of my adjustable intake. Slips.
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ceramic rope wrap.jpg (73.69 KiB) Viewed 7914 times
heres where it needs to be.jpg (74.77 KiB) Viewed 7913 times
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pezman
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### Ceramic rope wrap (and other assorted tongue twisters)

Where did you get the ceramic rope?

I have toyed with the idea of using high-temp adhesive and this sort of rope to fabricate a pj by using adhesive soaked ceramic rope wraped around an armature of some kind.

I forget why this went untried. It was either extreme laziness or it turned out to be a pricey technique, given that it was unproven -- probably a combination. I imagine that the idea of ending up with a hardened ball of yarn and goo that couldn't even be burned for disposal purposes was strangely unappealing.

There were a number of unknowns. For example, you might need some kind of clever weave for longitudinal strength.

And, as always, the flagon with the dragon has the potion with the poison, but the chalice with the palace has the brew that is true.

Which suggests the insanely obvious idea that ceramic rope wrap flame proof dragon flagons with which to brew true brew for palace chalices would wax wonderously worthwhile. But I digress (solely for the sake of twisting tongues).

Mike Everman
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LOL.
McMaster has the rope. The stuff I used is wound up 3 .25" unidirectional ropes, with a strengthening thread down each. It's not strong stuff, more like cotton. I ended up stuffing each coil down the gap with a dental tool.
Seal is good so far.
Mike
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