Startup of a Steam Pulse Jet Driven Model Boat - VIDEO

[WebPilot]

PS click here for movie of a cold boiler start up

[evildrome]

Forrest,

Thats very cool! I fancy building one myself. A couple of questions if I may:

1) I take it the coiled pipe is copper? What bore?

2) The burner is just a meths burner?

3) The pipes exiting the boat exit below the water line? Level with it?

Thanks,

Wilson Logan.

[Mark]

http://www.nmia.com/~vrbass/pop-pop/
http://users.bigpond.net.au/mechtoys/putt.html
http://www.pratherproducts.com/internet ... /putt.html
http://www.hilgartdata.com/grahamco/cruisers.htm
Mark

[WebPilot]

Forrest,

Thats very cool! I fancy building one myself. A couple of questions if I may:

1) I take it the coiled pipe is copper? What bore?

2) The burner is just a meths burner?

3) The pipes exiting the boat exit below the water line? Level with it?

Hello again, Wilson!

Long time, no hear - I would never have guessed it was you behind that "pseudonym".

Thanks.

1. Yes, it is Cu of 1/8" ID but I do not think that it is critical. What is critical is not to "kink" it when bending it.

2. I am unsure of the term "meths", but I used isopropyl alcohol. I ran this boat with a candle and also olive oil - but I found them very messy to use.

3. The pipes do exit below the water line. Level? Well I put mine level with the bilge. When it gets underway, the bow does rise a little, so they are not really level anymore.


Later (and happy building),

-fde

[WebPilot]

~~~~~~~~~~~~~~~~~ repairing broken link



Here is a picture of my 1st engine I created for the boat. It is much more difficult to build, but it would really honk!

I had problems with steam leaks where the pipes joined the chamber, so I went to the coiled Cu arrangement.

To me, it resembles the Star Trek Enterprise and I don't have the heart to throw it away. Someday, I shall solve the joint problem, but I have other projects underway that are more pressing.

Later,

-fde

[Mark]

You can also use a single piece of copper tubing with one end pinched closed. This might be thought of as a "half" of a typical putt putt engine. A fellow I conversed with was using such an apparatus to propel his canoe along a river. Not really the most efficient way to use heat but it worked. In a vague way, my piglet snorkeler is "half" of a typical valveless pulsejet.
Mark

[evildrome]

>Hello again, Wilson!

Hi Forrest,

>Long time, no hear -

I have been very busy... I'm now a Daddy!

http://www.pgoffline.com/images/Rachel_0502.JPG

http://www.pgoffline.com/images/Rachel_0552.jpg

> I would never have guessed it was you behind that "pseudonym".

Indeed! It is I!


>2. I am unsure of the term "meths",

Methylated spirits... Ethanol denatured by the addition of Methanol.

Cheers,

Wilson.

[WebPilot]

Dear Wilson,

Congratulations! - she's precious. Great photos! The first picture is simply striking. Are you a professional photog?

>>2. I am unsure of the term "meths",

>Methylated spirits... Ethanol denatured by the addition of Methanol.

Hmmm, I get it - denatured alcohol. It's a little "pricey" here in the States, which is why I went to isopropyl.

If you have any problems with Rachel's boat, email me.

Best wishes to you, the misses, and Rachel,

-fde

[Nick]

very nice work, i've always wondered if there is an upper limit to how big thses can be made?.
There is actually a website devoted to these little beasts they are called "pop-pop" boats as they used to be made with a thin brass sheet "engine" which would flex during running making a popping noise, check this out!.

http://www.nmia.com/~vrbass/pop-pop/buildpop.htm

or

http://www.pop-popboats.com/

Great fun!

Nick

[yipster]

biggest poppop boat i heard about was a small single seater boat going footstep speed.
have some smal and bigger putput tubing here i played with.
i really wonder what say "Steam Pulse Jet Driven" can evolve into.
keep me posted!

[evildrome]

Hi Forrest,


> The first picture is simply striking. Are you a professional photog?

Ah, its the wifes work. The shoulder is mine :)

Here's one I took:

http://www.pgoffline.com/images/Rachel_0276.JPG


>>2. I am unsure of the term "meths",

>Methylated spirits... Ethanol denatured by the addition of Methanol.

>>Hmmm, I get it - denatured alcohol. It's a little "pricey" here in the States, which is why I went to isopropyl.

Other way round here, Meths is cheap, Isopropyl is very expensive. I was lucky enough to live in Germany for a few years & when I returned I brought back 24 one litre bottles of Ethanol. Cost me about $2 a litre ($1/pint). You can't get it here. Or you can but the price is silly.


>>If you have any problems with Rachel's boat, email me.
>>Best wishes to you, the misses, and Rachel,

Thanks,

Wilson.

[WebPilot]

Wilson,

Figures, that there would be a world disparity in the price of alcohols.

The photo you took is nice, too. The clothing looks handmade?

--------

Nick,

>very nice work, i've always wondered if there is an upper limit to how big these can be made?.

Thanks, the boat did look nicer before I had to unsolder the original "engine" and replace it. It also has some rust on it now, that it didn't have a year ago. I need to paint her!

From my reading, they don't scale up.

Payne scrapped the idea, patented and developed a single tube design. I have a photograph of one of his designs in a rowboat, but heaven knows where it is now.

yipster, I wish you had pictures!

Later,

-fde

[larry cottrill]

From my reading, they don't scale up.

Payne scrapped the idea, patented and developed a single tube design. I have a photograph of one of his designs in a rowboat, but heaven knows where it is now.

Forrest -

Is there any chance that larger ones don't work just because it's impossible to keep a liquid lock against the vapor, i.e. something like failure of capillary action? If that's the case, you could try large, very flat rectangular or oval ducts of sufficient area. Or, batteries of parallel tubes banded together [yeah, I know, that would cut into the inherent simplicity of the design pretty badly].

L Cottrill

[WebPilot]

Larry,

Is there any chance that larger ones don't work just because it's impossible to keep a liquid lock against the vapor, ...

Yes, the interface breaks down in large scale designs from what I've read. It results minimally in little thrust; maximally, in no oscillation.

If that's the case, you could try large, very flat rectangular or oval ducts of sufficient area. Or, batteries of parallel tubes banded together.

I think thrust would suffer, you would wind up with a heavy engine, you would have the added problem of tube clogging due to debris pickup, heat transfer problems, ad infinitum.

However, I have no dynamic model, so I am not 100% sure.

Later,

-fde

[Nick]

"From my reading, they don't scale up"

i have had a bit of a think about this, these things are actually not steam engines or pulsejets they are Hot Air engines and they will scale up but you have to put a couple of non return valves in.

the design im thinking of is a proven design, Robert Sier wrote a book which includes this design.

the basic principle is that the "working fluid" is the air, its heated- it expands, its cooled- it contracts when the ends of the tubes leading to this chamber are filled with water you get that pumping action. the use of non return valves means water is drawn in on the contaction via one leg of the engine but can only get out of the other leg when expanding, there is a cross over tube to connect the two.

I will do a sketch when i can find the book!

Nick