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Anyone use a Zeiss Jena 2.5cc diesel?

Old 05-20-2011, 08:25 AM
  #26  
earlwb
 
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

The new head looks pretty good, i don't see any problems with it from the picture.

One normally just measures the bore and stroke of the engine, then uses the measurements to calculate the volume of a cylinder, that yields the engine displacement then.

Measure the height (h) of the cylinder. Height is sometimes referred to as the length



Measure the radius (r) of the cylinder. Radius is the distance from the outer edge to the center of the circle.  I simply measure the bore and then divide by half to get the radius.



Multiply the height by Pi. Square the radius. (Multiply the radius by itself) . 



Multiply the product from Step 3 by the product of Step 4. 



Write you answer in the proper cubic unit of measurement.


Old 05-20-2011, 08:32 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

The early model diesel engines used a simple formula of 33% ether, 33% kerosene or naphtha and 33% oil. The 1% could be amyl nitrite or something like that at the time.

Half way down here in this page they go into a good discussion of the different model diesel engine formulas that people use.
http://www.colinusher.info/Model%20Aircraft/fuel.html

Nowadays we can't get ether easily anymore, and the extra additives are hard to get too. So one can look and see if any of the brands of engine starter fluid has ether in it or not. some brands have more ether in them that others do. Then one can use some Cetane Booster fluid as a substitute for the additives we used to get. But then with you being in Croatia, you might have access to ether where we don't here.

Castor oil can be the medicinal castor oil they sell at the phamacy, but you need to get the castor oil without sugar or any flavor additives added to it. Here many of us use the Klotz Benol brand as it has a additive in it to allow it to mix better in the fuel. Our other brands are usually SIG Castor oil, etc. In the past they used heavy weight automobile oil such as 50 to 70 weight oil. The 50 weight aircooled motorcyle engine oil works well too. Oils at the time had very low sulpur content or zinc additives, so you could look for oils like that too.

With the old bushing engines with lapped pistons you want to have 25% oil in the fuel or more even depending on the engine type.
Old 05-21-2011, 08:42 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Hi Zvonko - If your Zeiss Jena has 2.5cc displcement, cylinder bore will be about 15.49mm. If 2.0cc, 14.01mm. Just unscrew the aluminum head muff and measure inside diameter of top of cylinder.

Your home-made aluminum cylinder muff should work just fine as long as it screws onto the cylinder nicely and the compression screw thread is reasonably good and the screw is long enough.... It is not a critical part with regard to fit.

The old standard diesel fuel recipe is 1/3 kerosene, 1/3 ethyl ether, and 1/3 oil. Most diesel enthusiastis regard castor oil as best. Component proportions are not critical. Most present-day modelers would cut the oil to about 20 percent and add the difference to the kerosene. Tiny, tiny engines generally require more ether to get them started. But if the ether is fresh, 20 percent ether is enough for engines such as yours. AND you can use an ignition improver, such as amyl nitrate. There are several chemicals that can be used. Easiest and safest is to buy an ignition improver meant for diesel engines such as in trucks. Label will tell the percentage of the actual ignition improver (at least in the USA). Do the math so you get about 1 1/2 final percent in your model engine fuel. And add the rest of the content of the can of ignition improver to your kerosene in calculating final percentages. Most of what is in the ignition improver can is low molecular weight hydrocarbons. Ignition improver allows ignition at slightly lower compression among other benefits.

You are fortunate to be able to buy your fuel components, including ether. In the USA we cannot buy ethyl ether because it is used by people who make illegal drugs!

Regards. -Gary
Old 05-21-2011, 11:01 AM
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gmedson
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Hi Zvonko - I posted this information earlier today but it does not appear even though I am listed as the most recent contributor to the thead. Arrgh! Here's another try...

If your Zeiss Jena is 2.5cc, cylinder bore should be about 15.49mm. If 2.0cc, 14.01mm. Just unscrew aluminum cylinder muff and measure inside dimension across top of cylinder.

Speaking about the muff, your home-made one should work fine. This is not a critical part.

With regard to fuel mix, the old classic recipe is 1/3 oil, 1/3 kerosene, and 1/3 ethyl ether. That will work ok for you, but most of today's enthusiasts reduce oil to about 20 percent. Castor oil is generally considered the best to use. Also, 20 percent ether is usually enough. If you reduce the ether and/or oil, increase kerosene to make up the difference. Modern model diesel fuels also contain an ignition improver, such as amyl nitrate. Reduces compression necessary for ignition, among other benefits. Saftest and best way to add ignition improver is to get a can of the stuff from your local struck stop or auto parts store. Is used in full-size diesel engines, such as trucks. Note the amount of the improver actually in the can and do the math so you end up with about 1 1/2 percent in your finished fuel. Balance of fluid in ignition improver can is just filler, a mixture of low-molecular weight hydrocarbons. Portion this to the kerosene fraction in your fuel when calculating how much of the different stuff to mix up.

Hope this helps. Hope this gets posted...

Regards. -Gary
Old 05-21-2011, 11:04 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Hmmm. Now they're BOTH there! Oh, well.. .
Old 05-21-2011, 08:56 PM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

I seem to remember an attempt to create a competition
capable 2.5 free flight engine with a rear rotaty induction
by Carl Zeis in the late fifties.If that is so it sure would be
a nice addition to one's collection.
Ralph
Old 05-24-2011, 01:35 AM
  #32  
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

I have managed to finaly make mesurements. 15,5 diamater that makes it a 2,5cc.
The message showed up in the threed 2 times.
Old 05-24-2011, 02:36 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Thanks for your info....Greet stuff.
I have managed to make a pin! the engine now is in OK condition and should be good for starting.
Now just to concertrate on the fuel formula....ether is the main problem now!.
I did find a can of Motor Start helper for diesel and other engines. But no cemical content on the label!!!
It does have that strange smell and it did expand the rubber parts of the fuel tank that I used for Glowplug engine. and the silicon tube went soft also, so I think that there is some ether in the can, also evaporising quickly.... Then I think I need some improver also cause when I tried to start the thing with no valve PIN it sometimes just made ONE ignition turn and then nothing.... resulting in flooded engine...Before I try to make a new formular I think I better try to get original ether , and try with no amyl nitrate....I recone it should start...
Thanks Guys Earl , Gmadeson, etc.
Old 05-30-2011, 03:47 AM
  #34  
Kiwi2
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Now that I have the engine in one peice, can I use Petrolej (used for heating and lights) I think its Kero, but called differently, ore can I use Zippo lighter fluid???, Soon I will get the Ether from a guy.... so I have some caster oil left from last atempts to mix a formular....OK then hope to hear from you soon.. thanks again to all...

Zvonko
Old 05-30-2011, 04:23 AM
  #35  
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Naphtha once was in competition with kerosene as one of the three main ingredients for model engine diesel fuel. Way back in 1947 and so on there was a lot of debates over which was best for the model diesel fuel.
Naphtha is used as lighter fluid here in the USA too.
http://en.wikipedia.org/wiki/Naphtha

I saw references to Petrolej being lamp oil, so it ought to work. You want the unscented version with no aromatic additives.

Old 08-16-2011, 12:25 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

hi, I was on hollidays, any way I got my Jena going but by the time I found my phone and started to take a small video, the fuel ran out....
Thanks ounce again to all of you. Now all I need to do is to change the posiotion of the pin in the rotary valve to make it spin the proper way.

And wait for my friend to get some more Ether, because the small amount that he manage to get me evapurated.....


Old 08-16-2011, 12:30 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Jena 2,5 diesel form zgudelj on youtube.......

I don't know how to put it on the forum, only photos aloud....

Old 08-16-2011, 01:50 AM
  #38  
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?


ORIGINAL: Kiwi2

I don't know how to put it on the forum, only photos aloud....
Just click on the "YouTube" button and insert the link.
Old 02-29-2012, 06:58 AM
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Default RE: Anyone use a Zeiss Jena 2.5cc diesel?

Dan and all..
I am having zero success finding a Zeiss Jena 1.0.. Anybody have one for sale? I want it for our Bugaboo to make it authentic.. The CS Mills does ok but it was flown with a Jena..
Any help out there?
Thank you
Al, Katie and Christopher
"Diesel Nutz"
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