Boll Aero 18

[lensman57]

what fires the engine if there is no glow plug?
great little engine like to know how it works .
thankyou.

Hi,

As explained by the other gentleman, the ignition is achieved by compression, once a gas is compressed the temp goes up untill it reahces a critical point where combustion takes place, but this is not all, for this class of compression engines the fuel required has to have an accelerator ( oxygenator) added to it to aid the ignition. In the old times that accelerator was either Ether or some other derivative of it such Amyl ether, these days because of security reasons such fuels are difficult to mix at home and have to be bought over the counter.
For your information there is another type of compression ignition engine called Glow Plug, these have a special plug or more accurately, a heater element that aids the start up using a current from a small battery and once the engine starts the current is disconnected, the fuel for this type of engine is generally called Glow plug fuel and is more easily available.

Regards,

A.G

 

[zimma]

For your information there is another type of compression ignition engine called Glow Plug, these have a special plug or more accurately, a heater element that aids the start up using a current from a small battery and once the engine starts the current is disconnected, the fuel for this type of engine is generally called Glow plug fuel and is more easily available.

Ahhh, that explains a few things for me too I had incorrectly assumed that a glow plug engine was just a spark engine, but using a different type of plug. I should really know these things, as my current engine build is a glow..... That's another fundamental build mistake avoided

 

[lensman57]

Hi Zimma,

Just to add to my previuos post, the glow plug does not cease functioning after the ignition starts, depending on the design, the miniature filament would still assist ignition , hence glow plug. This is apparently mostly achieved by a ctalytic process between the plug and the fuel and heat.
I have also been told that a glow plug engine is slightly more forgiving in manufacturing tolerances than a full compression ignition engine. Getting a Boll Aero to start is a difficult task itself, getting it to run is on another level, therfore congratulations to gentleman with the build log.

Regards,

A.G

 

[samuel10]

Hi is it hard to modify this engine to take a glow plug if so what would be the changes.
I am looking at machining. a simple engine i have built a small steam/air engine that worked great just looking to take this hobby further. any similar simple glow drawing would be great.

 

[samuel10]

On th fuel side of things how do you cut the.40mm which is .016 thou slot .
and has anyone gogt a better drawing of the fuel system .