Proposed Tire Rim Engine

[larry cottrill]

Rossco, have a seat - I might convince you that you'll end up liking this.

Use a small used tire rim, like an old VW rim or old trailer rim. The cutting of the sheets (red on the drawing) to form the chamber and ducts is pretty fancy, but then you just lay them in and weld solid. Mount the spark plug on the valve hole of the rim, and mount the fuel pipe wherever and however seems best to you. Finally, add the little augmentor sheet between the exhaust and the intake entrance.

Why would you want to do this? Here's the beauty of it: It is easy to mess with the augmentor design. Though you weld it in, this can be a pair of pretty light welds that you could grind out with a Dremel tool to change it. Or, maybe it would work to put the augmentor sheet in with muffler repair cement or some such, so you could just break it out to move it between the exhaust and intake. At any rate, easy stuff compared to a lot that you've tried.

What do you think?

L Cottrill

[Viv]

You left out the important bit of mounting it back on the axle so it goes round and round:-)

Viv

[larry cottrill]

You left out the important bit of mounting it back on the axle so it goes round and round:-)

I thought the fuel supply might be a bit tricky ;-)

L Cottrill

[Viv]

[quote="Larry Cottrill"][quote="Viv"]You left out the important bit of mounting it back on the axle so it goes round and round:-)[/quote]
I thought the fuel supply might be a bit tricky ;-)

L Cottrill[/quote]

Just put the tank in the middle and the fuel will get pumped by centrafugel force:-)

May be tricky to turn off though:-)

viv

[pezman]

Ingenious!

I had a similar thought using bicycle wheels (under the assumption that you can get titanium wheels) but gave up when I decided that the assembly would probably fly apart if you spun it at speads that would allow the rim to approach ram-jet velocity -- speaking of which ...

How about a design that is symmetrical (e.g. two combustors or maybe three around the edge). That way it could be designed to spin. This might be an ideal way to build a home-made ram-pressor.

A twist on this might be to use the exhaust from one jet to power the ejector feed for the next jet. That might lower the rotation speed that is needed to get efficient operation since the intake speed would be the sum of the rotational speed plus any boost that the ejector gives to the incoming air.

[Bruno Ogorelec]

I have visions of a riverboat with the paddlewheel powered by a circular ramjet.

Gives new meaning to old lyrics:

Big wheel keep on turning
Proud Mary keep on burning
Rolling, rolling, rolling on a river...

[Rossco]

mmmmmm Larry, FRESH AIR!

I always have an instant issue with these cyclic designs of yours in regard to the ejector action. They all seem to work with the exhast gas, not the fresh induced flow! Here, i think that you will have TOTAL exhast re-entering the engine, with maybe 10% fresh mixed in with it.

With this design, other than being readily built around an easily balanced, and spinable mount, its advantages are somewhat limited!
Although, that said, show me an ejector that i could see working and i will get straight onto it for you! Parts and tools would be ready to go right now.

Ive decided to work on the ejector first, i need pressureized and moving FRESH air before designing the CC.
At this point, i have some very promising concepts. By way of a sneek peek, i will say that there is much more to it than "in-out" ejection. Enough volume at any sort of pressure capability is needed to continue with this project.

Rossco

[pezman]

Moving away from the ejector thing for a bit, a tire-rim might be a pretty good basis for building a more conventional rampressor.

* Creat angled vanes between the "front" and "back" of the rim. These vanes would match the interior profile of the rim and would evvectively segment the rim into several separate chambers (at this opint, the chambers are open facing outward from the rim)
* Cut away the "front" and "back" wall of the rim between the vanes. At this point, the rim would now be a multi-vaned fan
* Put a flame holder (w/ fuel feed, spark etc) in each chamber.
* Weld a plate along the perimeter of the tire

At this point, you would effectively have several ramjets, all pointed in the same direction, such that they would spin the tire like a turbine. The interior profile of the rim would provide the diffusor/nozzle shape (though maybe not ideal). The device would need to spin at a frightening speed (say, 15000 rpm) to approach the speed of sound at the perimeter. Not sure it's a great idea to spin a heat-stressed tire rim at almost 10x it's nominal service speed, but it sure would be fun if it worked.

[larry cottrill]

At this point, you would effectively have several ramjets, all pointed in the same direction, such that they would spin the tire like a turbine. The interior profile of the rim would provide the diffusor/nozzle shape (though maybe not ideal). The device would need to spin at a frightening speed (say, 15000 rpm) to approach the speed of sound at the perimeter. Not sure it's a great idea to spin a heat-stressed tire rim at almost 10x it's nominal service speed, but it sure would be fun if it worked.

What a great plan! I have thought of doing a similar gimmick with four, five, six, etc. pulsejets, which would be slower. Don't ask how I plan to get them all started ...

With yours, you might try to talk the boys down at the local Tires'R'Us to spin-balance it for you ;-)

L Cottrill

[larry cottrill]

I always have an instant issue with these cyclic designs of yours in regard to the ejector action. They all seem to work with the exhast gas, not the fresh induced flow! Here, i think that you will have TOTAL exhast re-entering the engine, with maybe 10% fresh mixed in with it.

Rossco -

Unless you have obtained some evidence for that on your own, I really don't think it's the problem you envision. If an ejector is working well, the mixing action is very thorough and supposedly all takes place in the stream on the way into the throat, not farther 'down the chute'. In other words, by the time you're in the throat of the thing, you're supposed to have about all the mixing you're going to get. This is one reason why the gap between the driving stream exit (exhaust exit, in our case) and the throat is so important - it controls the entrainment and accomplishes most of the mixing action. Of course, I have no idea how to go about proving that it really works that way.

Do you think you have found evidence that you don't get decent mixing until farther down the line? If that's the case, then yes, it would certainly complicate what we're trying to do with the ejector, and the scheme shown here would be pretty hopeless.

Some experimentation required ...

L Cottrill

[larry cottrill]

Perhaps the best thing would be to arrange a test something like this drawing. What would be needed is to build three small, practically identical flat-sided ramjets arranged as shown. The slider would be used to vary gap G, which would affect the air entrainment and output density and gas speed. Throat length L would be variable via the sliding fit, which I don't think would need to be very snug.

Engine A would be run on forced air. Laminarity (lack of adequate mixing of fresh air and exhaust) would be tested by alternately trying to run Engines B and C, aspirated by the ejector output alone. Start with length L set as short as possible - if the mixture seems to give preference to one engine or the other, L could be lengthened to see if the bias can be eliminated by increasing the mixing path length.

L Cottrill

[Harabec]

Ok now what if this is spinning? the centrifical force might pich your fuel lines closed and work outthe spark plug. If its spinnig it could fly off as a top and do some real nasty things to you or anybody. But heres an idea: dinces its an old tire rim why not streagthin it so it can take bening spun round and roud 100 times a second.