Monster Putt Putt Boat DIY – Ver 2 – Build, Test, Analysis


This is a pop pop boat motor number 2
The super giant boat motor Just a piece of copper tube
and on this end I have split it with a hacksaw and the plan is to put some silicone in here
then to put a couple screws into those “ears” It’s hard to see. That will hold it in place
and the silicone will act as a sealant.
Then we snap the top back on and go from there. This is the inside. The silicone has not quite set yet And the outside When the silicone is dry I will snap the lid
on. Then I need to figure out a boat for it.
And this is with the lid on it. And for a size comparison She’s trying to go. We took an old paint thinner can
Cut it in half and folded the edges so it would not be sharp
It’s really trying to go. Pretty impressive
She likes to take a break every now and again. It’s sucking air too.
We need to weight the back end down so that it does not suck in air.
It really uses up fuel, it requires a lot of heat We took the weight out of the back so the nozzle is right at water level and it seems
to work a lot better. I think 1 of the problems is the boiler is
too big and the pipe is too big and it sucks too much water into the boiler and it takes
too much time to “re-cook” it. By getting the tube above water level, it’s
not sucking in so much water and it’s not cooling down the boiler.
It really spits. That’s the sound you want.


2 Responses

  1. tsbrownie

    June 2, 2014 8:26 am

    There's a lot of debate on how these work.  I'm going to put in my 2 cents worth here (Full disclosure: I'm not a rocket scientist).  I think it moves forward because the water coming in is moving much more slowly than the sudden steam powered pulse coming out: the difference between the 2 is the push forward.  Force = mass x acceleration.  The mass of water in is the same as the mass out, it's the acceleration that's different.  The acceleration in (I'm guessing) is significantly less than the acceleration out.  Plug in some made up numbers: Mass in = 1, mass out = 1.  Acceleration in =1, acceleration out = 2 so Fin = 1×1 = 1 and Fout = 1×2 = 2.  So the net force would be 1 in the forward direction.  Result: It moves.

  2. tsbrownie

    June 2, 2014 8:49 am

    I need to build another one with a large, *thin* boiler.  Thinking about using 2 pieces of sheet metal held together (pop rivets, screws???)  The hard part is fastening the tube to it securely and not having it penetrate the boiler much.


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