From:      skunk-works-digest-owner@mail.orst.edu
To:        skunk-works-digest@mail.orst.edu
Subject:   Skunk Works Digest V5 #415
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Skunk Works Digest       Sunday, 10 September 1995     Volume 05 : Number 415

In this issue:

	Re: Tier II Plus

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From: Charles_E._Smith.wbst200@xerox.com
Date: Sat, 9 Sep 1995 07:33:00 PDT
Subject: Re: Tier II Plus

All vehicles moving through air produce some type of  turbulence. This turbulence 
causes emmisions in the 53GHz (ish) range. Compression and shock waves create
fairly large disturbances relative to the background emmisions caused by 
the normal convective turbulence in the atmosphere. 

About "Stealth".
There is no way to completely mask an aircraft from radar. What you try to do
with stealth is to reduce the intensity of the return. By doing so the aircraft
can travel closer to the antenna without being detected.   
Ground radar SOP until very recently was to set up a line of radar systems side by side
with overlapping fan-shaped sweeps. The idea behind stealth was to limit the 
detection range such that the A/C could sneak in between the areas between
the "fans".

With the proliferation of cheap, mobile radar systems, this is no longer feasible. 
Also, its just a heck of a lot cheaper and quicker to put the Weasels up and 
keep the radars shut down. The Weasel is so simple- its pure beauty. Turn your
radar on an it gets destroyed, leave it off and its just as useless!
(See Dessert Storm for details.)
The AF used to tell Congress the 117 was undetectable. Now they admit it has
the radar sig of a "small bird". The only problem with that- is that not too 
many small birds fly at M 0.6 @ 30K ft.
Stealth is kind of weird, really. I guess its the "winglets" of the 90`s. Remember
when the Pentagon decided bombers should go M2? There`s always a new fad.

From a design standpoint, there are some stealthy things that do work.
The twin tails on the A10 mask the IR sig from the classic rear-quad pursuit
of an IR-guided weapon.  
The V-tail on the 117 covers the exhausts from lookdown systems. (The TE jet
exhausts)

With the big push for steerable nozzles at present, the idea of IR supression has gone 
by the wayside for fighter/air sup. design  (so I`m told, I haven`t designed any
F`s lately!- or ever!!)  
In any event, it will be interesting to  see what comes along next.

Chuck Smith
"Aerospace Engineer to the Stars"

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End of Skunk Works Digest V5 #415
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