What components are missing in a non-afterburning engine that an afterburning engine does, so that it can't use afterburning?

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    $\begingroup$ An afterburner :D $\endgroup$
    – ymb1
    Oct 4 '16 at 15:21
  • $\begingroup$ good one, I mean what components. $\endgroup$
    – anonymous
    Oct 4 '16 at 15:22
  • 4
    $\begingroup$ You might get a better response by asking the opposite. i.e. What components are required. $\endgroup$ Oct 4 '16 at 16:35
  • $\begingroup$ @anonymous What components? The afterburner. Seriously, you're asking a tautology. $\endgroup$ Oct 5 '16 at 7:39
  • $\begingroup$ @Notts90 The required component would be an afterburner. A better question would be "how do afterburners work?" but that's already answered on Wikipedia. $\endgroup$ Oct 5 '16 at 7:39

The afterburner, of course.

In simplest sense, the afterburner is just an extension attached to the engine where the fuel is dumped into the exhaust, resulting in an inefficient but huge increase in thrust.


Turbojet with and without afterburner; image from aerospaceweb.org

In the above image, you can see the basic schematic of the afterburner- it basically consists of a long tube placed in between the turbine and the nozzle in which additional fuel is added and burned. The (afterburner) tube is quite simple, consisting of mechanisms to spray fuel into the exhaust and ignite it.

This image shows an actual afterburner, from the F/A -18 (F404 engine). As you can see, its quite simple.


... sailor Ryan Draper ... inspects an F/A-18 afterburner in the jet shop aboard the Nimitz-class aircraft carrier USS George Washington (CVN 73). Image from gizmodo.com

  • 2
    $\begingroup$ About your point on efficiency: as I learned doing the equations in college, the thermal efficiency (a ratio) increases when in afterburner, but so does the fuel consumption (significantly) which reduces the "MPG" for the aircraft. $\endgroup$ Oct 4 '16 at 16:02
  • $\begingroup$ In simplest terms, an afterburner is just an inefficient bolt-on rocket engine. $\endgroup$
    – J...
    Oct 4 '16 at 17:06
  • $\begingroup$ How is the afterburner duct designed and why is the tube so long? Is its role and design trivial or is it very different from a non-afterburner nozzle? $\endgroup$
    – Cody P
    Oct 4 '16 at 17:14
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    $\begingroup$ @CodyP The duct essentially acts as a rocket engine combustion chamber. A jet can't burn all the oxygen it ingests without overheating so the leftovers get burned downstream to "reheat" the exhaust gas and increase its exit velocity. The length is required to allow sufficient combustion of the injected fuel and the design, as with most things in aerospace, is really not trivial (at least in real implementations). The nozzle has to be sized (and able to expand in afterburning mode) to prevent backpressure that can cause a compressor stall in the turbine. $\endgroup$
    – J...
    Oct 4 '16 at 17:28
  • 2
    $\begingroup$ @CodyP: The length of the afterburner is basically an open ended oven. If the tube is short all you'll be doing is dumping unburnt kerosene out the tail end of the engine. $\endgroup$
    – slebetman
    Oct 5 '16 at 3:48

A jet engine afterburner is an extended exhaust section containing extra fuel injectors. Since the jet engine upstream (i.e., before the turbine) will use little of the oxygen it ingests, additional fuel can be burned after the gas flow has left the turbines.—Wikipedia

Also additional igniters.


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