🚀 go-pugleaf

In <1jk3beINN6c4@mirror.digex.com> prb@access.digex.com (Pat) writes:

>	my problem with the shuttle is that they used Military safety amrgins.
>	Now when one flys a 747, one does not usually put the vehicle
>	past 1.25 G.  The vehicle is rated for 4 Gs.  The failure limit
>	is around 6 Gs.   99% of the time you will be below 1.25 Gs.
>	an emergency manuever may require you to pull 4 Gs,  everytthing
>	is sized for this.  if something unusual occurs you can exceed
>	the limit.  Hence 747's have ridden out hurricanes and supersonic
>	dives.  

>	Now an F-15  is rated for 9 Gs.  THe pilots will routinely
>	pull 9 Gs.  but at 10 Gs, structural damage is assumed
>	and the vehicle is overhauled.  Now F-15 pilots will
>	pull these high G forces in Training,  in operations,
>	in Combat and in emergencies.

I have to question this.  I don't have figures handy for the F-15
airframe, but a historical note may give a slightly clearer picture on
"Military safety margins" (if my memory isn't flawed).  The rated
plus-g for the F-4 was something like 5 g.  Pilots in Southeast Asia
almost routinely did 8-g manuevers when avoiding flak, etc., because
going outside the envelope was better than being shot down.  I don't
know of any aircraft that went down from structural failure, and I
would expect that if that had happened it would have been widely
publicized in the anti-war press of the day.

I would suspect that you would have more serious problems than
g-induced structural damage if you did 10-g manuevers in an F-15,
since you have almost assuredly exceeded the g-tolerance of the
wetware.  In point of fact, there have (apparently) been instances of
near-instantaneous GLoC which resulted in loss of aircraft in F-16s
doing 9-g pull-ups.  Structural damage from g loading ceased to be
much of a problem if the aircraft impacts dirt.  I also assume we're
not talking about jolt, but about sustained manuever, since I think
planes coming off a cat take higher jolt than 10 g.

-- 
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
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Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me.