There's more to Putt-Putt than the obstacles

[old man emu]

Red posted this over on the Funnies section: 

 

Here's an old idea worth investigating. Why not use the principle of the putt-putt boat engine to power a people-carrying boat? The putt-putt engine has none of what we consider moving parts. It only requires a heat source to boil a relatively small amount of water, so the cost of generating heat might be a whole lot less than the cost associated with either an internal or external combustion engine they we are familiar with.

 

It's very hard to explain this idea in writing, so here's a video in which the operation of a putt-putt engine is described. 

 

 

[facthunter]

I don't know how well it would work scaled up. Nev

[pmccarthy]

My dad had them as bathtub toys  in the 1930s.

[octave]

Built one when of these with my son when he was  younger. From memory we bought a kit from a company that sold science kits. I seem to remember it was a lot of fun although a little temperamental to get started.

[Bruce Tuncks]

Good question Nev, the answer may well be that it works so poorly its not worth building one...

I once built one, and it used a 3mm copper tube, so it was really small.

 

 

[old man emu]

2 hours ago, facthunter said:

I don't know how well it would work scaled up. Nev

I suppose there must be some ratio between the volume of the boiler and the volume of the tubes.

 

In the video, the presenter said that the forward motion was the result of unbalanced Momentum. Probably technically incorrect as I would invoke Newton's Third Law (equal and opposite forces), but that's a moot point at this stage.

 

It's pretty obvious that this propulsion system is akin to a jet system, so to use this system to propel a small boat, like a tinny, you would have to know the value of the friction between the tinny's hull and the water to  get an idea of the minimum Thrust needed just to get the tinny moving.  The Coefficient of Friction is going to vary with hull design and, I think, the speed of the boat. But those are things to consider for a wider application of the method. First step is to see if a putt-putt engine could do it.

 

Here's a research paper on the subject. https://www.researchgate.net/publication/318000523_Factors_Influencing_Performance_of_a_Model_Steam_Engine_Putt-Putt_Boat

[Yenn]

One of those crackpot ideas was actually used. The torroidal tit engine.

The theory was that the cylinder of an engine had acircular depression in the top and in the depression there was a sharp spike pointing up to the cylinder head and it was well faired into the cylinder. The engine ran on soap bubbles with a goldfish in the carburettor. Air was sucked in and the goldfish blew a bubble which went into the descending dylinder, then the piston came up compressing the bubble. At TDC the torroidal tit burst the bubble forcing the cylinder down.

The design was modified slightly and became the AEC diesel engine which was used in London buses.

That was the story I was told when I was an apprentice working on AEC engines.

[octave]

 

Edited September 3, 2022 by octave
incorrect information

[onetrack]

I'm afraid the first video just left me confused - perhaps it's because the bloke isn't really good at explaining it all.

 

To acquire forward momentum, you must need to have an energy source, and expend energy to acquire that forward momentum.

 

The energy is coming from burning the oil in the candle - so why not simply burn the oil in a little combustion engine?

 

I guess the candle advantage is there's no moving parts, and no frictional losses, so the energy transfer level is improved over an IC engine.

[willedoo]

On 03/09/2022 at 2:18 PM, facthunter said:

I don't know how well it would work scaled up. Nev

one problem would be finding a big enough spoon.

[facthunter]

Scale up a bumblebee and it won't fly.. Nev

[old man emu]

Ha! Ha! I bought two tins of sardines this week. Call me Admiral!

[willedoo]

It reminds me a bit of how a pulse jet works.

[Jerry_Atrick]

8 hours ago, old man emu said:

Ha! Ha! I bought two tins of sardines this week. Call me Admiral!

Weren't they the ones John rejected?

[old man emu]

10 hours ago, willedoo said:

It reminds me a bit of how a pulse jet works.

Some mornings I'm just happy I have a pulse.

[nomadpete]

On 10/09/2022 at 7:10 AM, old man emu said:

Some mornings I'm just happy I have a pulse.

Every morning I'm happy to have a pulse.

 

(And yes, I do check)

[spacesailor]

Every time , I,m asked " good morning " , I now answer, " every mornings good, with my New hip  " . LoL

spacesailor

[old man emu]

Casey is an old man who wants to be a teen
He goes to all the dances, and they call him cha-cha King
He cha-chas when the band is playin' rock 'n' roll
He tries to keep in time, but the beat leaves him cold

Because he's too pooped to pop, is too old-school
Hips gettin' weaker when he tries to do this stroll