Ronin of the Spirit

Because reality is beautiful.

Pulse jets

So I’ve designed most of my jet. It has no moving parts and it is supercharged by the exhaust of the adjacent jet (Its going to be made in pairs.) I’ve run into a problem with the intake valve.
The intake valve has to be something called a pneumatic diode. For those of you who don’t speak techno-bable, that means it has to let air flow one way, but not the other.

The intake valve I planned on using was something called a valvular conduit. Like a good many interesting ideas it was invented by a crazy man named Nikola Tesla. Theres a couple problems though:

(1.) Tesla said in the patent that it provided 200 times more resistance in one direction that the other. But none of his notes or assistants ever actually saw him run tests on it.

(2.) The main body of the prototype jet is 2″ in diameter. A valvular conduit of 5.5 stages (What Tesla used in his patent diagram.) scales to about 70″ long for my jet. Thats pretty crazy.

(3.) Tesla was famous for stating the theoretical efficiency as the real world efficiency. He invented a really neat gas turbine that worked by the gas slowly sliding of plates in a very tight radial spiral rather than slamming into blades in a very low helix coaxial spiral. They’re very neat, but they get about half the efficiency he said they would. What if the VC is the same way?

(4.) The VC isn’t especially easy to make. Particularly in the back yard. And there is no math to back up its construction. The only way to make one is to scale the patent drawing. With no math, its pretty hard to analyze one.

(5.) The properties of air in a set of small tubes is really, really odd. The smaller the tube gets the more air acts like water. (Huh, you say?) When air and water are the same pressure, temperature, and velocity, then air will exert 1/14 the force as water if the tube/s they are flowing through is the same size. This gets really strange when dealing with small shapes.
If you want to model the flight of a fruit fly for instance and you want to make the wings about 8″ long, you have to fly it in mineral oil to get the same (scaled) forces on the wing.
When object gets small enough, the fluid you are trying to move thru it (or around it) gets like jello. I’m having a hard time running the numbers.

(6.) And exhaust is 4 times thicker than inlet air. So it has to be sized that way.

(7.) And the combustion chamber has to be small. If its not, the pressure can’t build up fast enough and it farts instead of thrusts.

I’ll keep working on it.


April 22, 2007 - Posted by | Uncategorized


  1. Well, you have one thing right…we don’t speak techno-babble. However, having discussed this with you at length, all I have to say, and this is more for anyone else reading, you have a phenomenal idea and you will get it working. It may take redesigning Tesla’s valvular conduit but you will get it running.

    I am very excited. I can’t wait for you to rattle our windows and scare the neighbors when you fire it up.

    Comment by Becky | April 22, 2007 | Reply

  2. Oh, you and your pulse jets. Next you’ll be making some silly little hover craft that a single man can stand on and fly around on… what they already did make that. Mainly I have come here to remind you of that little helicopter design with dual main rotors, placed on an angle, you said would cause too much stress. Yet, they have newly designed a helicopter that indeed places two main rotors on a 15 degree pitch from each other, intercrossing as they spin creating a more stable lift. Now of course, my design had the blades at a 40 degree pitch but whats a few measily degrees when it comes to engineering design. Anyway, according to my watch, we should have been on the moon by now and we still boil water for power so unless your “Pulse jets” can get me to the moon and back, I’ll stick with fuel sucking turbo diesel engines thank you. Save the whales….for dinner.

    Comment by Christopher H | April 25, 2007 | Reply

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