tlfd29
Posts: 80
Joined: Sun Jul 31, 2005 3:41 am

Afterburner Stages

Fri Dec 08, 2006 12:27 pm

What does it mean when they say an aircraft has a six stage afterburner? What are the stages composed of? Are there engines with less or more stages?
 
boeingfixer
Posts: 573
Joined: Fri Jul 29, 2005 2:02 am

RE: Afterburner Stages

Fri Dec 08, 2006 3:48 pm

Stages are actually know as Zones. Zones are essentially separate fuel spay manifolds before the AB flame holder that allow more control over the AB power output. If less AB is required, only 1 zone could be used. As more AB power is required the additional zones will be activated by the FADEC or AB fuel control unit. Early AB's had only one stage or zone = on or off. There can be anywhere from 1 zone to 6+ zones depending on engine type.

Cheers,

John
Cheers, John YYC
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: Afterburner Stages

Fri Dec 08, 2006 11:40 pm

To my knowledge, stages or zones on the afterburner allow more lee-way in terms of afterburner-control.

In the old days, the afterburners were basically ON or OFF, and guzzled a thousand pounds of fuel every minute. Adding some ability to have more control of the afterburner, the J-79 was fitted with a modulated afterburner with five different settings. The highest setting had the most thrust and fuel burn. The J-75, at least some models, featured a Min-AB, in addition to a Max AB setting.

The J-58 used on the blackbird, has vernier control over the afterburner; able to regulate it just like one would regulate the engine RPM.
 
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Starlionblue
Posts: 17211
Joined: Fri Feb 27, 2004 9:54 pm

RE: Afterburner Stages

Sat Dec 09, 2006 2:33 am

Quoting Blackbird (Reply 2):

In the old days, the afterburners were basically ON or OFF, and guzzled a thousand pounds of fuel every minute.

Not to mention being like an elephant kicking you in the kidneys when it was punched on.

Apart from the modulation ability mentioned above, zoned afterburners have a gentler transition from no afterburner to full (and back) is gained. This is better for both the airframe and the pilot. Note that it doesn't take two minutes, but even a subsecond zone stagger will make the transition much smoother.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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