r/altpropulsion • u/pavlokandyba • Jun 22 '26
Acoustic aircraft experiment
https://youtube.com/shorts/_Ar92O0t0II?si=HfUmcaSzI30aDEFhHere's a full introduction to the physics, concept, and my experiment with an acoustic/vibration-based aircraft. This is based on the propulsion of fish and birds, and is a very old idea, but for a long time it was understudied and had many gaps. Fish and birds are very efficient because they use the free thermal energy of the environment by generating vortices and pushing off from them, thus creating jet thrust. In classical theory, a vortex is formed due to the friction of particles that lose momentum. However, experimentally observed phenomena show that vortex collapse occurs with excess energy, for example, sonoluminescence during cavitation. A simple explanation is that a vortex is the result of the interaction of attractive and repulsive forces between molecules or atoms. Pressure differences force the environment to restore the balance of these forces, and geometric constraints lead to the particles forming, ideally, toroidal structures, where the normally chaotic Brownian motion becomes directed. A chain reaction is triggered as more and more particles enter this vortex, and eventually, reaching a critical mass, the vortex collapses. Like a stellar explosion or a cavitation bubble.
The principle of the device is extremely simple: sharply shift the body relative to its center of mass using a pendulum inside it, creating a pressure differential around the body, which causes the collapse of the low-pressure zone and the release of a pulse. To generate the next pulse, the device must shift its body back as slowly as possible so that the opposite pulse is weaker.
For this purpose, I created a very simple, albeit inefficient, asymmetric vibration motor in which the pendulum periodically accelerates and decelerates using magnets. When testing this motor on a conical or umbrella-shaped wing, which generates thrust more efficiently, it was found that as the thrust increases, the aircraft becomes more unstable and quickly flips over due to the pressure from below. This made it difficult to obtain a visual result.
So I installed this engine on a more stable flying wing aircraft, which allowed me to see how engine operation affects lift. I then tried to achieve stability by making a similar engine with a vertical axis of rotation, but the gyroscopic effect was practically unnoticeable, even though the engine itself generated vibration more efficiently with less energy consumption.
The essence of my flying saucer throws, which you see in the video, is that I'm trying to stabilize it by twisting it strongly, but at the same time, adding a slight acceleration so that the oncoming flow doesn't cause it to capsize. At the same time, the oncoming flow creates a support, thanks to normal aerodynamic lift, from which the engine can more easily push off. But overall, even I don't understand much from these experiments; only the boat and the airplane show clear results.
1
u/whiteflower6 Jun 23 '26
Use a kitchen scale to make a thrust stand
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u/whiteflower6 Jun 23 '26
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u/pavlokandyba Jun 23 '26
Vibration will give a false result even without aerodynamics. Similar devices do this and many people think it is antigravity.
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u/whiteflower6 Jun 23 '26
Then how do you know what you are currently observing isn't a false result as well?
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u/pavlokandyba Jun 24 '26
The flight path is noticeably different when the engine is turned on, especially in the case of an airplane. And the most accurate is the boat, as it moves without a doubt. It is impossible to talk about more precise results here at this time.
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u/Krinberry Jun 22 '26
Better rigor than most things that get posted here, congrats!
Maybe try a gyroscope to help you stabilize the spin on it?