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From: pur-ee!luj@gus16.ecn.purdue.edu (Jun Lu)
Newsgroups: sci.military
Subject: Re: F-117A performance?
Message-ID: <1991Feb13.223541.8373@cbnews.att.com>
Date: 13 Feb 91 22:35:41 GMT
References: <1991Feb5.043703.6484@cbnews.att.com> <1991Feb6.033318.22925@cbnews.att.com> <1991Feb7.021146.4777@cbnews.att.com>
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From: pur-ee!luj@gus16.ecn.purdue.edu (Jun Lu)
>
>The F-18 is also designed with an inherent pitch instability.  This allows
>  it to pitch up rather quickly, while the computer gives the plane the 
>  illusion of great stability.  F-18 drivers often comment on how they love

Computer deos not give the illusion. Neither can it provide stability
mystically.  It is the on board _control system_ that does job -- it
generates the control signal using feedback principal, and acutators receving
the signals produce control forces to affect the control surfaces(aileron,
rudder, ...)of the airplane. This effectively modifies the closed-loop 
system's dynamics, making it a stable system. 

For F-18, it uses a digital controller, implemented by a digital computer. 
which just runs the control algorithms and generates the control signal ...
Actuators do the physical job ...
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