Glow engine

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minh-thanh

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kadora !
Try four stroke glow plug : I will try it .

ixb1 !
Ordinary glow engine if it stops when battery is disconnected, it is caused by too rich fuel mix or low compression ratio...But in this method of carburation i dont know.
Small two stroke also needs plenty of oil for cooling and lubrication. Literarly say oil must spray from exhaust.

I will check it again.

Keith whiddett
it needs a propeller for cooling and much lighter will run faster. Propeller size 9 x 6 or 9x4 : I will try it

Thanks ixb1 for the plan .
Thanks for all suggestions .
I will check and redo....I hope it will be better .
 

Mechanicboy

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There is evaporated fuel into the carburetor instead atomized fuel mix into the carburetor, but it ran! :eek:

Use ordinary carburetor with spray bar due the engine need oil from fuel to keep compression better + 4 stroke glow plug ("F" stamped on glow plug to example). Compression ratio must be 8:1 -9:1 to keep engine running without battery attached to glow plug and the glow plug is glowing by catalytic reaction from methanol too.

http://adriansmodelaeroengines.com/catalog/main.php?cat_id=153
 

Johno1958

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Very nice runner Minh Thanh congratulations :).
John
 

minh-thanh

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Hi all !
Updated and finished :
Now it runs without battery connection. It did not work well because I unfix too much, some parts were not good, but it was a learning experience for me, I learned a lot of things when doing it


Thank you very much ! Thank you all !
 

lohring

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Two strokes are a great introduction to engine building. They are very simple and work even if not perfectly designed or built. I learned most of what I know about manufacturing by building a model racing engine in high school. It was also the start of my fascination with two stroke design.

In small engines, friction is by far the most important factor because the power producing displacement decreases much more quickly with size than the surface area of parts like the cylinder. Ball crankshaft bearings have become standard. Some engines have also used needle connecting rod big end bearings.

Sealing also becomes more critical since clearances also don't decrease as quickly as displacement. Before careful machining was standard, ringed aluminum pistons were used in steel (sometimes hardened or chromed) cylinders. The final solution in small engines has been lapped fits between the cylinder and piston using materials with similar rates of expansion. In order of increased performance and difficulty these materials are cast iron on steel, high silicon aluminum on chromed brass, and high silicon aluminum on chromed high silicon aluminum.

After these considerations, the cylinder head volume is important. It sets the ignition timing for glow engines and needs to be matched with the plug heat range and fuel. Racing engine tuners use head shims and machine lots of head buttons. After all this comes the port shape and timing. Cross flow and reverse flow engines are the easiest to build, but loop flow engines are more powerful with carefully aimed ports and a tuned pipe. All designs can work well with open exhaust. See the pictures below. Tuned pipes have more than doubled the output of today's race engines over the simple engine I built long ago.

Keep on refining your engine. It will teach you a lot.

Lohring Miller

Miller High School Engine.jpg
cyl_flows.jpg
 

minh-thanh

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Hi all !
I want to learn more about it and after changing the structure, but keep true - approximate - technical requirements: cylinder diameter, stroke ....
20180911_230632.jpg
20180911_194736.jpg
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20180911_230726.jpg
 

minh-thanh

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It's running slow because I'm adjust it slow :D , If I adjust it too fast it will turn the needle - because the needle is not tightened
 

lohring

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If you are interested, I've written a series of articles on two stroke engines. The first series is in 4 parts on High Power Two Stroke Design:

http://namba.com/content/library/propwash/2012/November/#/14/
http://namba.com/content/library/propwash/2013/March/#/3/
http://namba.com/content/library/propwash/2013/October/#/8/
http://namba.com/content/library/propwash/2014/October/#/7/

The second series is just starting on the history, design , and building of model racing two strokes. The first article is at http://namba.com/content/library/propwash/2018/october/14/ and it discusses the history of the nitro engine. The following articles will go into the details of building high power model glow engines.

Lohring Miller
 
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