The exhaust system of the F-117 is known as the platypus exhaust.  Instead
of being round like a regular jet engine, this exhaust is flat and wide.  It
is designed to mix cold air with the exhaust to quickly reduce the infra-red
(or heat) signature of the engines.  As you can guess the engines do not
have afterburners (or what the British call reheat.)

Also, the underside of the wing is longer than the topside at the exhaust so
that viewed from underneath, the heat emission is greatly reduced as cold
air has already been mixed in.  Viewed from the top, the heat signature is
much greater.  This type of design was called a sugar scoop when it was
tried on the Dragon Lady (U-2).

The F-117 Stealth Fighter designation is somewhat of a misnomer; the
aircraft is not a fighter at all but an attack aircraft.  Indeed it carries
no machine guns, cannon or missiles for air-to-air combat.  It only carries
two "smart bombs".  Its purpose is to go into a high-risk (heavily defended)
area and attack high-value targets.  It relies on its stealth technology for
self-defense.  It is not particularly fast as it doesn't even go supersonic.
It does have a long endurance however.

Final bits of trivia; it has two FLIRs, Forward Looking Infra Red, one of
them in front, and the other pointed down (more like a DLIR,) no radar, 4
computers (which is why it has those 4 probes up front,) and is so unstable
that it simply cannot be flown without the computers.

I would love the opportunity to visit the Castle Air Museum.  According to
the web page, they have quite a collection.  There are several aircraft
there I have not seen up close:  an Avro Vulcan, a B-45 Tornado and believe
it or not, a CF-100 Canuck.  This last one is a Canadian aircraft designed
and built in Canada in the 1950s, by Avro Canada in Toronto.  Its follow-on
is the fabled CF-105 Arrow, whose program was abruptly terminated.

There is of course, an SR-71 on static at Castle.

Thanks for the invite Bill; I hope to take you up on it.  Better bring
earplugs though, I tend to drone on and on about the various aircrafts in
these museum.

Denys
-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
Of William L. Brandt
Sent: Wednesday, July 27, 2005 12:57 AM
To: [log in to unmask]
Subject: [HP3000-L] OT: Fun space shuttle facts!

John asked:"Would any  aviation buffs care to speculate on what is so secret
about the aft view  of that aircraft?"

John just guessing (using the SWAG Methodology) but I wonder if the engine
exhausts have some heat deflecting technology (to evade missiles?)

BTW for years this squadron was based near Tonopah NV - unknown to much of
the world - and I heard of at least 1 story of an unsuspecting Cessna pilot
straying near their airspace and being "escorted" by a fighter to a base -

If Denys ever gets out this way I'll have to show him the collection at the
old Castle AFB - I haven't seen Wright-Patterson either...

Bill

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