Guus Flogel demonstrates one of his wooden shoe pop-pop boats.
How to make a pop-pop boat
Simple toy submarine. Attach motor and battery holder to bit of styrofoam using rubber bands; break off bits of styrofoam to neutralise buoyancy. Small and cheap enough to introduce to a public swimming pool clandestinely.
Propellor quite easy to make using small bits of plastic packaging glued to a plastic bush. Shape and dimensions surprisingly un-critical. Make it about 15mm diameter. If done in a school play 'sub hunt': line everyone up along the edge of the pool, throw submarines into pool with motors running, shout "go", when anyone catches one they bring it to you whereupon you throw it into an empty area of the pool.
If two batteries are used, the sub goes much faster but stability becomes a problem. This design is stable even though it only has one propellor.
This is a toy airboat, it uses the submarine ideas.
This is another radio controlled version, the fan can be rotated through 360 degrees, this makes it very manouverable, also nothing essential goes below the water line, so it doesn't get caught on weeds.
Link to movie of airboat
This is a version of the toy submarine that automatically avoids obstacles.
This is a very simple radio controlled boat, it uses the radio from a single channel car; it has the disadvantage that you have to reverse in order to steer.
how to make a putt-putt boat; difficult but very highly recommended
Here we see a potentially dangerous impasse between a duck & a putt-putt boat
This one has two engines side-by-side, boat just made from bit of styrofoam; foil insulation on top of boiler. Each engine has 2 straws, one half the length of the other.
simplified pop-pop design
This is slater harrison's design, simplified to use less glue & dexterity.
Cut ends off coke can, fold round ruler
trim off excess
bead of araldite
sellotape while glue sets
araldite in end
crimp with pliers or vice
fold over & crimp again
straws in other end
link to instructions for simpler pop-pop engine
pop-pop engine pumping water
some very elaborate examples
movie of orca immitating outboard motor sound
how a pop-pop engine works
by jeff bindon
A PopPop engine is a water pulse jet. To
function there must be air and water inside. It starts
to gently pulse because as water nears the
boiling point, a bubble of steam forms explosively
and nudges the water in the tubes into motion. But
the steam immediately condenses and the water
flows back again. The water columns in the tubes
act like "pistons" and their momentum causes the
pressure to fluctuate above and below the
atmosphere and the membrane to flex in and out.
As the pressure drops inside the engine, the
water finds itself above the boiling point and
steam forms rapidly ('flashing') and this drives
the water "pistons" outwards and the explosive
formation of steam is swamped. Steam condenses
on the cold wet surfaces exposed by the retreating
water "pistons" and the pressure falls. Soon it is
below the atmosphere which then drives the
"water pistons" inwards to compress the steam
and air inside. The air acts as a spring to bounce
the water "pistons" outwards again.. Warm water
is expelled from the engine and cold water is
taken in. When it eventually reaches the boiler, its
dissolved air is released.
Gradually air builds up
and will be pushed further and further down the
tubes until small bubbles are expelled. To satisfy
the Second Law of Thermodynamics, heat is
expelled from the engine via the ejected pulses.
boat I made up from one of jeff's kits
detail of boiler & burner
James Rumsey's steamboat with beamless Newcomen engine
Early development of steamboat
more ambitious pop-pop engine
please email me any comments, my address is
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bishop wilkins on the advantages of submarines (1648)
1. ‘Tis private ; a man may thus go to any coast of the world invisibly, without being discovered or prevented in his journey.
2. ‘Tis safe; from the uncertainty of Tides, and the violence of Tempests . . . from Pirates and Robbers .. . from ice
and great frosts which doe so much endanger the passage towards the Poles.
3. It may be of very great advantage against a Navy of enemies, who by this means may be undermined in the water and blown up.
4. It may be of a special use for the relief of any place that is besieged by water, to convey unto them invisible supplies....
5. It may be of unspeakable benefit for submarine experiments and discoveries: as,
The deep caverns and subterraneous passages where the seawater in the course of its circulation doth vent itself
into other places and the like. The nature and kinds of fishes, the severall arts of catching them, by alluring them
with lights, by placing nets around the sides of this Vessell, shooting the greater sort of them with guns. ... These fish
may serve not only for food, but for fewell likewise, in respect of that oyl which may be extracted from them.
The many fresh springs that may probably be met with in the bottom of the sea will serve for the supply of drink
But above all, the discovery of submarine treasures is more especially considerable, not only in regard of what
hath been drowned by wrecks, but the several precious things that grow there, as Pearl, Coral Mines, with
innumerable other things of great value.
All kinds of arts and manufactures may be exercised in this Vessell. The observations made by it, may be both
written and (if need were) printed here likewise. Severall Colonies may thus inhabit, having their children born and
bred up without the knowledge of land, who could not chuse but be amazed ... upon the discovery of this upper
Mathematical Magick, Vol. II