If you read the specs (http://www.astronautix.com/m/mr-103.html http://www.astronautix.com/m/mr-103.html) of the thrusters in question, you can see that they do

If you read the specs (http://www.astronautix.com/m/mr-103.html http://www.astronautix.com/m/mr-103.html) of the thrusters in question, you can see that they do "spew flames" and there is a combustion chamber: > Combustion Chamber Pressure: 4.35-23.9 atm. Combustion Chamber Temperature: 800 Celsius. Combustion Chamber Cooling Method: radiative. Duty Cycle: 0.008 sec minimum to unlimited maximum burn. 750,000 pulses.