Model Turbine for N Gauge Loco

[medusa]

Jeff wanted to see the flames. Well, let me tell you the whole story.

It all started when I lay down with a really bad influenza two years ago... hardly could do anything else than stay in bed and surf the web with a small tablet computer. Rambling around I found photos and info on the Union Pacific turbine locos.
Well, long years ago I was in aerospace research for some years... colleagues of me worked on turboengine CFD calculations, was quite fascinating stuff. So, a train powered by a turbine was a big thought. Moreover when my head was still fuzzy from fever. Somehow I decided to kitbash a GTEL 8500 and bought a cheap 2nd hand ConCor Alco PB-1 dummy model from Ebay. A spontaneous base for the B unit.
 

That's how it started. After I was well again, I scratched my head about (myself). Of course, with my aerospace past a hollow model without a turbine inside was a bit boring idea. So I searched for a while for really small cooling fans which might be used as a turbine wheel in the model. There are chip coolers available, 15x15mm wide brushless which indeed fit inside a N gauge car shell. The wheel has only 12mm diameter, and they're not really cheap. One of these became the base for the model of the prototype GE-5 modified powerhouse turbine inside the GTEL 8500 B-unit.

 

Modelling stated with the Concor shell. I drilled an angled 10mm hole in one end for the exhaust funnel. Drilled and filed the prominent doors in the sides of the car. And, of course, sanded off the PB-1 cooling grills in the upper part. The bulls eye windows were closed by drops of epoxy.
 

The turbine case model itself was made of cardboard parts. I glued first the turbine case to the small fan and adapted the inner structure of the car bottom to fit both in. The inner side of the turbine case was painted black.

 

After a pause of a year, next was the compressor stage of the turbine. Here is no real wheel inside, it's just a tube. Centered inside a toothpick serves as main shaft of the turbine. A small black disk blocks light from the diffusor end shining through the entire model (would look really silly "hey, I'm hollow"). However, air still can pass through it.
Between the compressor and the turbine case the prototype GE-5 turbine has a ring of 10 combustion chambers. Turned out I had only place left for 8... made the chambers also from tiny cardboard tubes. Inner spacing 3mm to leave space for 3mm LEDs.
 

Since hydrocarbons burn with blue flame in an excess of air/oxygen, I bought blue LEDs for some fire effect inside. Again a year passed until I fit them in these days. The soldering of the wires was some challenge since it is all to easy to kill diodes with a too hot soldering iron. Electrical feed is by two copper rings, one of them hidden as structural stringer on the compressor case, the other one the "fuel line" of the combustion chambers. Test after soldering showed all LEDs survived. Phew.

 

Because the turbine model now was complete (despite of exhaust and suction ports, gearbox, generators,...) I painted it. Made it machine grey with a brass fuel line. The wires for electrical feed of LEDs and fan were secured by small blobs of epoxy.
Then the firing tests started. :)
Later I will drive the model with 3.3V from a small regulator PCB. Needed to estimate the current limiter resistor for the LEDs so they give nice blue "flames" when the fan spins at full speed. For this I set up a temporary wiring with a pot and a Li battery. This way I could turn up the fire easily. ;)
Doing so showed up some holes left in the paint. Looked like microscopic leaky seals with hot burning gas hissing out... will have to fix that later.


That's the current state. BTW, all these years I thought about a good story how this beast made it into a Japanese scenery... :D
 

[cteno4]

Medusa,

 

You are mad, utterly mad, and I love it! Great project and great story! Kudos!

 

Next will be a real gas turbine engine to clear snow from your tracks!

 

Jeff

[medusa]

I had a feeling that I'm in the right place here in the forum. :D

 

A still more otaku idea is to take a (real) turbine for a model helicopter. There are turboshaft engines about the size of a soup can available for the guys who are really serious about modelling helis (and have the necessary bucks). The engines run on propane but some even take real kerosene.

Those turbines have roughly around 10kW torque power output on the shaft and could drive the generator of a small motorbike. All this should fit into a gauge 1 car. Soon you will find youself fiddeling with 12V motors in the bogies...

 

See for example the JetCat: http://jetcat.de/images/spm5.jpg

Website: http://jetcat.de/jetcatturbinen/marine--turbine.htm

 

Ok that's enough OT for today. I'll stay with my N scale turbine model and work today on the inlet duct.

Edited January 14, 2017 by medusa

[kvp]

You mean like this one?

[medusa]

YES!!!!    (Isn't the sound great?)

 

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My today's modelling is less spectacular - just the inlet duct. The new parts are clearly visible since they're not yet painted.

A vertical port is in the car, coming from the roof duct. Of course I had to drill and file another opening for it, and some of the PB-1 roof detail had to go as well...

 

The most fiddeling was required when it came to the cable feedtroughs. This inlet port/duct has really to feed air into the turbine model so the little fan can blow it out the back. Cables were in the way everywhere. I found a solution which unfortunalely isn't visible here.