Wacky Weird and Way-unconventional idea

Jets that defy normal classification

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Zippiot
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Wacky Weird and Way-unconventional idea

Post by Zippiot » Thu Sep 11, 2008 8:44 pm

First off a disclaimer: I dont know what I'm doing.
Background: I get 3-5 days in the shop a month now and want to get back into jets; got my AA in machining and Machinist practices and have access to a mini lathe, minimill, mig welder and some standard shop tools.
I'm an Aerospace Engr student, currently transferring schools to get a better education. Just swapped majors from Mechanical Engr so not too many principals are familiar to me.
What I want to accomplish: I once built a turbine, it was beyond amazing to me. Done a few ramjets they are fun, and one crappy pulsejet that doesnt work well. I want to re-invent the wheel, just for me!! No reason I dont/wouldn't build a standard jet, this is just to satisfy my curiosity. So I want to do something new and exciting, something weird just to stamp my name on it and say "im just as surprized you are it works..."
Idea#1

Incorporate a vane compressor into a small turbine to improve comrpession.

On the computer at work so a picture will have to wait until tonight, but for now:
A rotary vane compressor is a simple device to make pressurized air. My idea is for the Compressor from a cars turbocharger feeds into the rotary vane compressor, that feeds into the combustion chamber which pushes the turbine completing the process. The rotary vane comrpessor would have to be geared down and offset slightly, so here is where my idea gets laughed at.

I think you can have a ring and sun gear to downgear the RVC from the shaft, and since it is offset and spits air out the side...the combustion chamber would be off to the side of the RVC. I assume since the CC of a regular small turbine is a good portion of the jets girth that the CC for this jet would also have to be quite large. It would be fugly but it just might work.

So the front of the jet looks like a turbocharger, compressor spools air into a pipe like in a turbo as opposed to a standard Centri-flow jet where it enters an axial [kinda] flow and is shot straight back into the CC. Instead this pipe is bent into the vane compressor. The RVC will intake from the flat side but exhaust from the rounded side. The large CC will intake from the rounded side and shoot straight back out, towards the turbine which is designed like the intake.

So the air does some freaky twists and turns but the jet itself is reasonably cyllindrical in shape.


Gearing the RVC to the main shaft. The shaft will have a gear, sun gear on it if you will. The shaft of the RVC will be a hollow pipe with a ring gear (teeth on the inside of the ring). The large hollow pipe will have bearings at each side of its housing, which the main shaft will pass through. The main shaft has its own set of bearings attached to the compressor and turbine housings. So essentially there is an offset bearing that is wide enough for the main shaft to pass through uninterupted. So even though they are geared together and offset they dont wiggle in any way. This allows me to gear down the RVC because I dont think it should spin anywhere near as fast as the Turbine.

Lube is important!! For the RVC to have a long successful life it needs lube. I imagine it can self aspiriate by placing a tube where the compressor feeds into the RVC, the fast moving turbulent air should suck enough oil to keep the RCV sealed up tight!

I sureleft many thing out but work is buggin me so I'll post back later


[was not spell checked :) ]
*slightly edited in my spare time so it appears I speak english*
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Re: Wacky Weird and Way-unconventional idea

Post by Viv » Fri Sep 12, 2008 5:24 pm

Looks like you are thinking out side the box there a bit mate ;-) let me ask you a basic question first though, were is the horse power to turn that vane pump going to come from?

I love the fact you worked all the other stuff out first but some times you gotta start with the maths the same as the turbine guys do because it takes real shaft horse power to turn a compressor and move the amount of air per second needed for self sustaining engines let alone have some power left over to do some thing useful with.

The Kompressor on a AMG version of the Mercedes E65 takes over a 100 horsepower, how big a vane pump did you have in mind?

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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Fri Sep 12, 2008 7:57 pm

http://www.mech.uwa.edu.au/NWS/ae/java_ ... tvane.html

The more compression you demand of an RVC the more shaft power it takes, I feel a 2 blade "low compression" version would only require 5-15 of the shaft hp.

Would it make up the difference is the math I need to work out...
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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Fri Sep 12, 2008 8:00 pm

Problem found!!
The backflow of high pressure...
The 2 blade would backflow less often but more violently, a 6 blade would backflow more often but less violently.

It may not be an issue, as the vanes would seal the pressure from escaping through the turbocharger's compressor. But the pressure changes might mess with combustion, anyone know of a way to help regulate the pressure? Maybe an expansion chamber beore the CC would help.


No internet at home so all the nice pics I drew cant be posted yet.
Last edited by Zippiot on Fri Sep 12, 2008 8:19 pm, edited 1 time in total.
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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Fri Sep 12, 2008 8:12 pm

Here is a very good explaination and multimedia about how they work.
http://www.pneumofore.com/img/operation.swf
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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Sat Sep 13, 2008 4:45 am

OMG
Its the age old argument between auto experts!!!

Turbocharger vs supercharger...

Using exhaust to add compression (twin or multispool turbine) or using shaft power (the couldn't possibly work idea I posted)


imo: dragsters use superchargers and they are the fastest piston vehicles.
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Re: Wacky Weird and Way-unconventional idea

Post by Viv » Sat Sep 13, 2008 1:32 pm

Zippiot wrote:OMG
Its the age old argument between auto experts!!!

Turbocharger vs supercharger...

Using exhaust to add compression (twin or multispool turbine) or using shaft power (the couldn't possibly work idea I posted)


imo: dragsters use superchargers and they are the fastest piston vehicles.
:) yes that and more, but both take "work" to operate! one is from a free turbine driven from the exhaust gas waste energy and the other is driven directly by the crankshaft (shaft horse power :D )

I think the real problem is friction as the vane type will have a higher friction than a normal centrifugal compressor, by this I mean plain old mechanical friction, its those losses plus your sun and planet reducer losses that will be the problem.

As a note dragsters use both supercharging and turbo charging, traditionally superchargers have always been considered faster to responde but lower down the rev range power, turbos are slower to responde (turbo lag) and work better at higher rev ranges, so both are complementary.

If you want to see turbo charging to extreme then search tractor pulling and what they do to raise a 175 horsepower tractor to 1500 horsepower, it involves three stages (or 4) turbo charging with water spray inter cooling but not a lot else.

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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Sat Sep 13, 2008 3:27 pm

Also the 1/4 mile melts the tractor drag racing motors so they can only do 1/8 mile :P
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Re: Wacky Weird and Way-unconventional idea

Post by Viv » Sat Sep 13, 2008 3:35 pm

Zippiot wrote:Also the 1/4 mile melts the tractor drag racing motors so they can only do 1/8 mile :P
Dragging that big sled may have some thing to do with that :D

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Re: Wacky Weird and Way-unconventional idea

Post by Zippiot » Sat Sep 13, 2008 5:32 pm

I remember reading that a freepower turbine has the most "power" at stall, I think Jon wrote it somewhere...
Could we make this into the turbocharger style, where the RVC is powered by the freepower turbine.
I recall in a turbine the compressor uses upwards of 60% of the available shaft power and that 40% remaining wouldnt likely be enough to drive the RVC
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Re: Wacky Weird and Way-unconventional idea

Post by LeighS » Wed May 13, 2009 3:42 pm

Hi all! I'm a newbie so go easy on me... ;) It seems to me that this is simply a two stage compression system but using two different types of compressor. Why not simply use two turbos? Is it just for the novelty? If so then go for it! If you're simply looking for extra compression, then two turbos is much easier and works extremely well. I've built a turbo jet with two compression stages. The only issue is the absolutely phenomenal heat generated in the compression. I had to incorporate some serious intercooling to overcome this and get some real efficiency out of it. And to avoid destroying the second stage compressor!

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