Will this toy engine work at full size? (yes)

But what was that giant duck doing there? The sponsor is Jane Street. Fine out more about their internship programme here: www.janestreet.com/internships/?utm_source=youtube…

There's a society somewhere in our galaxy where pop-pop boats are the most advanced form of propulsion

my childhood dreams after watching ponyo have been made real

My Father and I crafted and sold handmade pop pop boats on a website 20 yrs ago. The boats were called “featherlite steam boats” because they were press formed from aluminum sheets and we included certificates with serial numbers for each one. These were the only pop pop boats with small rudder on the rear. Fun times ! Although my Father has passed away some time ago I still have the press forms to create the boat hull and top and all parts to braze the engine parts.

An anecdote from the UK. In 1946, I had a tinplate boat about the size of a slipper. In the centre was a small container into which one poured about 20ml of methylated spirits. Around the rim of the container were two layers of smallbore pipe. The two pipetails were soldered either side of the rudder, one being 10mm above the other. One lit the meths ,waited for a few minutes for the water to heat and expand in the top pipe before watching the boat cross the pond in silence. I still have it in my nostalgia box.

Thought they really had built a life-size pop pop boat for Steve to ride but then I saw the rubber ducky for scale and realised they'd simply shrunk Steve down enough to fit in a toy boat...

There's two ways to make a human sized put-out boat. I feel like this one is the "one horse sized duck" strategy. But I think I'd like to see the "100 duck sizes horses" strategy too

Interesting, Steve… A point missed by yourself and the others is that a pulsating water engine (PWE) or 'pop pop', 'Tok Tok' etc., doesn't have to have the flat plate. Toy ones only had a flat diaphragm to make an engine noise.  A simple coil of tubing over the flame works better as the flash boiler, and was used in larger model boats like the beautiful, pressed aluminium 'Miss England' by Victory Industries, sold just after WW2, as well as in many kit and scratch built models.  The PWE engine works by rapidly boiling the water in the flash boiler, which turns to steam and forces the water in the tail pipes out quickly. As the steam hits the cold pipes, it condenses, while the exiting water providing the thrust carries on moving down the long tail pipes under its own inertia (some small toy 'pop pops' only had a single tail pipe). The moving slug of water's inertia then creates a vacuum after the pressure of the steam bubble disappears, which eventually pulls in water, increasing the cooling of the condensing steam and refilling the tube, and 'boiler' section, with liquid. The coil (or chamber/boiler) over the heat source gets rapidly boiled again to send another pulse of steam down the system as it overcomes the back pressure from the now condensed previous bubble of steam and the drawn in water, which is pushed out to provide thrust (but not a lot). A 'full size' PWE powered boat was actually built before WW2, though only a dinghy in size and very slow, it was virtually silent and used to stalk and net waterfowl on a calm pond. My late father had a huge collection of old steam powered toys, including a lot of PWEs. Most of the PWEs were small candle or spirit heated 'pop pops', but some commercially sold ones, usually methylated spirit fired, were as big as half a metre long or more.

I think drawing water in from a rear-facing opening slows things down a bit. I'd suggest having one pipe forward with a check valve that only allows water in and the other pipe backward with a check valve that only allows water out.

As an estonian, seeing such a big content creator visit the small country and seeing a physics youtuber go to ahhaa is really exciting :D

Now I know why USS Enterprise has it's shape 🙂 It'a an interstellar pop-pop boat!

I would love to see a pop pop boat with many many smaller engines. Like your eight cubes separately, the surface area would scale with the volume. But maybe the medium engine, so you wouldn’t need 1 million of the mini ones.

Had a bit of a fascination with these boats and this video was fun to watch with a great educational piece on how scaling up works, doesn't work. Brilliant work and great to see those guys where happy to have you come and test their boat.

Yeah, square-cube law really defines the size of some things when it comes to engineering. You can't scale things up too much, and also can't scale things down too much. Some engineering solutions just work best at certain scales. And also various material properties come into play.

I love the whole sequence in Ponyo when she enlarges the little pop pop boat and I’m so glad to know it would actually work for real!

The spring and weight model was such an elegant way to visualize a complex concept. Thank you for such wonderful videos.

It's cool that it works scaled up! At the sacrifice of 1:1 modeling after the source material, I bet this would get better performance in terms of speed if done in parallel with a specific size. If the reservoir size that provides the most propulsion that also has the least amount of weight / water can be worked out, I bet it might be able to go a lot faster. I'm no expert but a V8 pop-pop boat sounds pretty cool.

In chemical engineering, there are concepts to overcome the square-cube law. Instead of a scale-up of a reactor (bigger tank), you can do scale-out (more reactors). In extremis, this results in chip-size reactors with lots of surface area. To bring this into the context of the video, just use 10,000 of the minisized pop pop boats :)

a system of check valves to allow it to pull water from the front and expell out the back would probably be another improvement to the design.

This is a very interesting and fun experiment. In Japan, it is called a pom pom boat. It is fresh in my mind that it appeared in the anime "Ponyo". I thought it would not work with a scaled-up model, but was a bit surprised to find out that it could work with low efficiency. The biggest surprise, however, was their attempt at a full model. It's fantastic.👏👏👏