Link to original video: https://youtu.be/e3eX4FKQHLM

Saw them on Ewe Toob and had to build one. Just a quickie job and putting around in the kitchen sink. I can see the great grandsons and I building bigger, more detailed versions.

Don't bother turning the sound up, just SWMBO and BiL chatting in the background. You can see the top of the "boiler" oilcanning as the steam bubbles drive the water out the tubes.

I dont get what is making it run. This, is a advanced technology isn't it Paul ? Something a mad scientist up in Maine would discover. This changes everything.

quote:

Originally posted by David Lee:
I dont get what is making it run. This, is a advanced technology isn't it Paul ? Something a mad scientist up in Maine would discover. This changes everything.

I don't fully understand it myself. The boiler is made from the domed bottom of a soda can, covered with a piece of the aluminum epoxied over the top to form a seal.

Two tubes are run from the bottom of the boiler and out the back of the boat.

You prime the jet tubes and the boiler with water (totaling a couple of teaspoonsful) and light a candle under it. After a minute or so, a steam bubble forms and pushes water out the tubes making for a jet-drive type propulsion.

Where I get confused is that somewhere in the cycle, fresh water is drawn into the boiler and the thing will run as long as the candle (or other heat source) lasts.

You can see the pulse effect at the rear of the "boat" as well as the top of the boiler oilcanning up and down.

The one part I do sort of get is that the water exiting the tube is forced into a straight jet by the tube, while the water being drawn in comes in from all directions 360° around the mouth of the tube so the inflow doesn't cancel the reaction force of the outflow. Beyond that, I'm clueless.

If someone understands and cares to explain the physics of it, I'd love to hear about it.

Damn!...now I want some kipper snacks

It works quite well. I dont grasp how but it looks like it is going back and forth between drawing in and outputting water. Someone on this Forum can explain what its doing. Pretty cool Paul.

quote:

Originally posted by Bisleyblackhawk:
Damn!...now I want some kipper snacks

My wife hates when I eat those things. Must love me tho, bought another 3 tins of them when we went shopping today...

How cool! I'd never heard of these. Wikipedia gives a pretty good explanation of the science...

Basically it's a pulse jet engine. The candle heats the water in the boiler to steam, which forces the columns of water in the exhaust tubes backward, and the boat forward. The boiler is now dry and cannot produce any more steam. Internal pressure drops, pulling water back into the tubes. You would expect the boat to then move backward to conserve momentum, but in fact the forward-moving columns of water quickly hit the wall of the boiler, retransferring all of their momentum back to the boat and cancelling out nearly all backward motion.



(The assymetry of the intake/exhaust helps to some degree, but is not the primary propulsion driver.)

This message has been edited. Last edited by: kkina,

I imagine fitting a small remote controlled rudder on a larger version of PHPaul's boat and wondering how long you could putt around on a pond or other small still body of water with it.

quote:

Originally posted by kkina:
How cool! I'd never heard of these. Wikipedia gives a pretty good explanation of the science...

Basically it's a pulse jet engine. The candle heats the water in the boiler to steam, which forces the columns of water in the exhaust tubes backward, and the boat forward. The boiler is now dry and cannot produce any more steam. Internal pressure drops, pulling water back into the tubes. You would expect the boat to then move backward to conserve momentum, but in fact the forward-moving columns of water quickly hit the wall of the boiler, retransferring all of their momentum back to the boat and cancelling out nearly all backward motion.



(The assymetry of the intake/exhaust helps to some degree, but is not the primary propulsion driver.)

Interesting! Thanks for the description.

quote:

Originally posted by Black Pepper:
I imagine fitting a small remote controlled rudder on a larger version of PHPaul's boat and wondering how long you could putt around on a pond or other small still body of water with it.

That's been done, I may have to look into an inexpensive single channel RC rig. Always been fascinated by RC, but too spendy for me.

That’s really neat!

quote:

Originally posted by PHPaul:

quote:

Originally posted by Black Pepper:
I imagine fitting a small remote controlled rudder on a larger version of PHPaul's boat and wondering how long you could putt around on a pond or other small still body of water with it.

That's been done, I may have to look into an inexpensive single channel RC rig. Always been fascinated by RC, but too spendy for me.

Curiosity got the best of me, so I built a bigger one with room for an inexpensive RC rig. Waiting on calm weather to try it out.

This is going to be interesting to see. Next comes a 5 footer with dual Bernzomatics installed for a heat sorce..

quote:

Originally posted by David Lee:
This is going to be interesting to see. Next comes a 5 footer with dual Bernzomatics installed for a heat sorce..

I like the way you think! I might go with butane micro-torches as an intermediate step tho...

So THIS is what you Northern boys do when the snow drifts lock you in?

quote:

Originally posted by slabsides45:
So THIS is what you Northern boys do when the snow drifts lock you in?

Well, my banjo is in the shop...

Needs to add a lil gun turrett with a barrel and a cork on a rubber band... . The pressure builds, the pressure builds, the pressure builds and, Pop. Or maybe a tin of Jiffy Pop so you and the little ones can have a snack when the ship comes in.