Now why does nitro engine stay running? Presuming your carburetor is tuned correctly. This is where science comes into play. There is heat generated in the combustion cycle. This heat is called "the catalytic reaction".

A catalytic reaction occurs causing platinum to glow in the presence of "methyl-alcohol," or "methanol". This catalytic reaction will occur on it's own without any outside power source. All of this only comes onto play during low rpm and when there is not enough heat being generated to burn all the fuel vapor. The catalytic reaction changes as rpms and temperature rise. This has just been a very basic explanation of how a glow plug works at low rpm or idle.