Dual-mode exit area scheduling?

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Discussion Overview

The discussion revolves around the concept of dual-mode exit area scheduling in aircraft nozzles, particularly in relation to military jets like the F-22 and F-16. Participants explore the mechanisms of exit area scheduling as an automatic control system that adjusts based on flight conditions and demands.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • Some participants describe dual-mode exit area scheduling as an automatic control system that varies the engine's exit area based on flight regime and thrust demands.
  • One participant mentions that the exit area opens to allow supersonic flow, increasing exhaust velocity and thrust during takeoff.
  • There is speculation that the dual mode aspect may involve two redundant computer controls managing the scheduling.
  • Another participant inquires about supersonic dash capability and the specific controls (A8 and A9) of the F-16's nozzle, noting that A8 refers to the throat area and A9 to the exit area.
  • One participant expresses uncertainty about the workings of the A8 and A9 controls and suggests that another participant, Andre, may have more information.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints regarding the specifics of dual-mode exit area scheduling and the controls of the F-16 nozzle. There is no consensus on the details of the A8 and A9 controls or the implications of supersonic dash capability.

Contextual Notes

Participants reference specific technical aspects of aircraft design and control systems, but there are unresolved questions about the operation of the A8 and A9 controls and the full implications of dual-mode scheduling.

Who May Find This Useful

Individuals interested in aerospace engineering, military aviation technology, and control systems in aircraft may find this discussion relevant.

perfectz
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dual-mode exit area scheduling?

what is dual-mode exit area scheduling?
 
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You leave through the door or the window?
 
mgb_phys said:
You leave through the door or the window?

Dude I am talking about nozzles of F-22, F-16 ...
Detailed explanation please...
 
I'll have to look at the "dual mode" part (sounds like a controls systems detail) but the exit area scheduling is an automatic control system that varies the exit area of the engine dependent on the flight regime and demands. You'll notice in videos of an aircraft ramping up to take off an aircraft carrier, as the thrust demand is increased, the exit area of the exhaust is opened to allow supersonic flow and increase the exhaust velocity and thus, more thrust. The scheduling is a "calibration" of sorts to provide the best possible engine operation at a given demand.

I would venture a guess that the dual mode aspect is that there are two computer controls that redundantly control the scheduling.

There is an interesting section on the thrust vectoring control nozzle system on a NASA re outfitted F-15 here:
http://www.nasa.gov/centers/dryden/history/pastprojects/Active/pub_online/setp_d6.html

Look under the Nozzle Actuation and Nozzle Control Computer and Control Algorithm sections.
 
Last edited:
What is supersonic dash capability, and you know something about independent A8 and A9 controls of nozzle in F-16?
 
Supersonic dash is the ability to go to a supersonic speed that is outside or at the edge of the aircraft's normal operating envelope. Most attack have a dash to target so as to get the aircraft in and out very quickly. The actual range and speed of the dash is a part of the overall design and requirements.

As far as the F-16 A8 and A9 controls, a little search shows that the A8 area is the throat area and the A9 area is the exit area of the nozzle. How those controls work I have no idea. Andre should chime in here. He would be able to answer that.
 
andre where are you?
 
You could try PM'ing him.
 

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