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A magnificent work of Swedish engineering – a pulse jet powered sledge on a frozen lake

This is c. 7 years old, but it is quite marvellous and a tribute to the great tradition of engineering in Sweden. A video done by a Swedish chap who built himself a pulse-jet powered sledge or ‘ice boat’ to run around on frozen lakes. It is basically a V1 doodlebug-type engine on a frame, with some seats and steering. What strikes me is the need for some form of suspension.

I have set the video where it has its first ‘ice road test’.

19 comments to A magnificent work of Swedish engineering – a pulse jet powered sledge on a frozen lake

  • Kirk

    Honestly had no idea that Sweden had rednecks…

  • Awesome! Also some epic comments:

    Wife said I can’t have toys with moving parts… these guys have put me back in the game!

    The lack of consideration for safety is refreshing.

    Impressive that they packed so many ways to die into one hobby!

    impractical, dangerous, fuel inefficient, loud, i’ll take 20

  • XC

    I would add that this is practically a middle finger homage to WWII Germany, which always makes me glad.


  • Runcie Balspune

    We have our own mad inventors, thanks


    If you think that’s nuts, check out other inventions.

  • Paul Marks


  • JDN

    Here’s a guy on a dry lake instead of a frozen lake:

  • Stonyground

    One of the guys who worked on developing the pulse jet engines was Walter Kaaden. After the war he went to work at the MZ motorcycle factory and started applying some of the principles of pulse jet technology to two stroke motorcycle exhaust systems. Once his ideas were applied to racing motorcycles more widely, two strokes became completely dominant and two strokes and four strokes haven’t competed on a level playing field since. I heartily recommend the book Stealing Speed by Matt Oxley, if you can find a copy. It tells a fascinating story about how the technology was originally stolen by Suzuki during the cold War.

  • It may be my speakers, but I have heard much smaller pulsejets make much louder noises. But this wasn’t the classical valved pulsejet, it was a resonant one. That might explain the difference.

  • llamas

    @ Stonyground – I knew Mat Oxley quite well in the late 1970s, when he was a clubman racer. Then, as now, he spells it with one ‘t’.



  • Paul Marks

    Kirk – Sweden also has bikers.

    The outside world sees one aspect of Sweden (one sort of Swedish person) – but there are very different aspects (very different Swedish people – people who still have the spirit of the Vikings).

    For example, Sweden did not have a lockdown.

  • llamas

    Sweden and Norway are also the historic home of a whole technology area of 2-cycle and 4-cycle diesel, semi-diesel, hot-bulb and glowplug oil engines, the archetypes being Bolinder et al. In the late C19 and early C20, Scandinavia was at the forefront of development of this family of engines, many of which rely on quite-complicated and -directed gas flows and contraflows, and there’s still any-number of them puttering away over there, many in fishing vessels and sawmills. So they know something about gas flow.



  • george m weinberg

    I don’t understand how this could work Doesn’t a pulse jet need to already be moving to provide thrust? I thought the V1s were launched with “ski jumps” before the actual pulse jet kicked in. How do these thing get started?

  • Mr Ed


    Just where the video starts you seen a flame flare out from the initial ignition, and then at 3:15 it seems to kick in with a burst out the pipe after the ignition flare fades. I think that it works as this hot, expanding mix rushes out the rear from the combustion chamber leading to a partial vacuum behind it (or a relative pressure drop) which leads to air coming in through the inlet which is mixed with what I assume is propane, and it becomes self-sustaining. Unlike the Doodlebug V-1 it does not need to have airborne launch velocity from the get-go, that’s presumably this year’s project.

  • Philip Scott Thomas


    Colin Furze, the insane and insanely entertaining engineer whom Runcie Balspune linked to above explains how to get a pulse jet running here.

  • Mr Ed

    Thank you PST, it looks like our Swedish friends have a more straightforward starter system. And all this reminded me of the absolute zenith of British can-do, don’t care attitude, which is this clip of some chaps test-running what is said to be a Rolls-Royce Viper jet engine by the simple expedient of tethering it to a wooden pallet on a fork-lift truck and seeing just how vigorous it can get. And do not say that they take no precautions, there is a fire extinguisher at hand at 0:56.

  • bobby b

    ” . . . and seeing just how vigorous it can get.”

    Reminded me of our first-time install of nitrous on a car engine many decades ago. Oops. Runaway.

  • llamas

    The V1 engine did not need launch velocity to start or run the pulse-jet engine, the engine was started with the missile stationary, using a blast of compressed air and a spark plug, and run up to full power over a period of 10-15 seconds before the steam-powered catapult was tripped and the missile launched. The catapult was necessary because the engine, while it had enough power to sustain cruising flight, was not powerful enough for the missile to take off. Some experimental mobile versions of the V1 used jettisoned rocket boosters to achieve the same result.

    The Argus engine of the V1 was a little different than those we see in these and similar videos – it had a relatively-short combustion chamber and the pulse action of the engine was controlled by mechanical intake shutters, whereas the engines we see here create the pulse action by means of longer combustion chambers which set up a resonant flow of gas, resulting in the pulse reaction at the exhaust. The Argus engine ran (relatively) slowly, with a pulse rate of only about 40 Hz, while these engines have a higher pulse rate. Neither engine type relies on ram-air velocity to start or run, although increased ram air velocity increases the power output of both types, as tending to increase the compression of the charge before ignition.



  • llamas

    This link takes you to a video of an original Argus V1 engine starting and running, showing that it does not require airflow through the engine to start and, once it is running and the pulse sequence is established, both the compressed air used for starting and the spark plug used to ignite the first charges can be removed and the engine will stay running.

    A smarter reader than I points out that it would likely be impossible to start a valve-regulated pulse-jet engine like the Argus with any significant airflow going through it. As the shutters at the front of the combustion chamber tend to be forced open by the airflow, there is no mechanism by which they can be closed to contain a fuel-air charge which could then be ignited. Any attempt to inject fuel into an existing airflow would simply be blown out of the tailpipe before it could be ignited. In fact, the engine can only be started when it is stationary, as that’s the only condition in which an air-fuel charge can be established in the combustion chamber long enough to be ignited, forcing the intake shutters closed and establishing the sequence of high and low pressure pulses which cause the engine to run. He adds that the Argus engine required to be ‘choked’ to start reliably, by partly-blocking the tailpipe when first firing the engine, to ensure full combustion and allow the engine temperature to rise high enough to ignite subsequent charges.




  • Stonyground

    Oops my bad, I just checked the book and you are right. He is an excellent writer and, though I knew the basic story of Degner’s defection, the book fills in a mass of details about the aftermath of WWII, the Cold War and motorcycle racing technology.

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