From: chadwemy@wpi.WPI.EDU (Chad Barret Wemyss)
Newsgroups: sci.aeronautics
Subject: Re: V/STOL fighters
Date: 21 Jan 1993 16:32:21 GMT
Organization: Worcester Polytechnic Institute
Distribution: world
NNTP-Posting-Host: wpi.wpi.edu

In article <alien.02mo@acheron.amigans.gen.nz> alien@acheron.amigans.gen.nz (Ross Smith) writes:
>
>The two Yakovlev V/STOL fighters, the Yak-38 and Yak-141, both hover on
>three engines, and are fitted with an automatic ejection system (Eskem)
>which basically chucks the pilot overboard if anything goes wrong.  The
>designers' attitude seems to be that if you lose an engine while hovering,
>you're going to crash and there's no point in trying to avoid it.  If
>they're right, would it be better to build single-engine fighters (sort of
>a scaled-up Harrier)?  A single-engine fighter might be safer in the hover,
>but less safe in combat; a twin would at least have a chance of making a
>conventional landing after a Sidewinder up a tailpipe.  In any case, would
>a single-engine fighter the size of an F-15/F-22/MiG-31/Su-27 be practical
>at all?
>
The biggest combat problem of a VTOL aircraft is that of heat-seeking missiles.
In any aircraft where the engine thrust is used to lift the plane, the exhaust 
nozzles must be arranged around the CG (Center of Gravity).  Since the engines
are the major heat source in an aircraft that is flying at sub-sonic speeds, 
this is where the missiles will most likely hit.  With the engines amidships 
(around the CG), even a relatively small blast, such as that of a shoulder-
launched SAM, will cause catastrophic engine, control and structural damage.  
A larger missile like the Sidewinder will cut the plane in half.  (All right, 
maybe an exaggeration, but it will more than likely rupture fuel and hydraulic 
lines, cut power systems and flight control systems, and turn the engine into 
a large number of high-speed fragments, which will then cut the aircraft in 
half from the inside.)  

I do agree that near-front airfields are increasingly vulnerable to attack, and
that the smartest way to go is VTOL aircraft.  However, there is only a slim 
chance that any air force will be willing to put up the money required to make 
a large VTOL fighter or strike aircraft.  While the Harrier is a good plane, it
is limited in range for the interdiction/strike mission, and in both payload 
and staying time for the Close Air Support (CAS) mission.  The major advantage 
of a VTOL aircraft in CAS is the ability to base them much closer to the front 
lines than conventional FW aircraft.  This allows a much faster response time, 
and a greater dispersal of the aircraft to prevent counter-attack.  

Scaling up the Harrier to make it more useful in either mission would require a
large expenditure in a world of shrinking defense budgets.  While I'm sure that
the Marines would like a larger, faster, longer-ranged replacement for the 
Harrier, and even the Air Force might want something like that (in spite of the
Air Force prejudice against anything with an A- designator), I don't think that
it will happen in the near future.  


Chad Wemyss
Worcester Polytechnic Institute
Xref: sparky sci.aeronautics:2826 sci.research.careers:1801 sci.space:19836 soc.college.grad:2373