Path: utzoo!attcan!uunet!mitel!sce!cognos!geovision!alastair
From: alastair@geovision.uucp (Alastair Mayer)
Newsgroups: sci.space.shuttle
Subject: Re: shuttle landing sites
Message-ID: <434@geovision.UUCP>
Date: 4 Nov 88 16:54:20 GMT
References: <2137@aplcomm.jhuapl.edu> <5590@ecsvax.uncecs.edu> <794@hadron.UUCP> <5157@polyslo.CalPoly.EDU> <2349@ssc-vax.UUCP> <1144@orion.cf.uci.edu>
Reply-To: alastair@geovision.UUCP (Alastair Mayer)
Organization: GeoVision Corp, Ottawa, Canada
Lines: 46

In article <1144@orion.cf.uci.edu> dkrause@orion.cf.uci.edu (Doug Krause) writes:
>In article <2349@ssc-vax.UUCP> adolph@ssc-vax.UUCP (Mark C. Adolph) writes:
>>In article <5157@polyslo.CalPoly.EDU>, steve@polyslo.CalPoly.EDU (Steve DeJarnett) writes:
>>> As
>>> I recall (this is a LONG time back, so I could be wrong), the runway at
>>> KSC is reenforced a LOT to support the shuttle weight.  Although I would 
>>> guess that the shuttle landing empty would be light enough for most 
>>> commercial airport runways, I'm not sure what the weight of a fully laden
>>> shuttle would be, and whether these runways could support the load.  
>>
>>Does a fully laden shuttle really weigh more than a 747-400 loaded with
>>~550 passengers and their vacation souvenirs?
>
>I can't quote weights of either craft, but I know that if a 747 going
>out of LAX has to abort the flight, it has to dump most of it's fuel
>into the Pacific before returning to land.  Now I don't know if the
>weak part is the landing gear or the runway, but a loaded 747 is ob-
>viously VERY heavy.

Don't forget, the KSC shuttle landing strip not only has to support
the landing weight of the orbiter, but that of a fully-loaded 747 -
specifically, the NASA 747 ferry aircraft with the shuttle orbiter
strapped to it's back.  I guarantee you that is considerably heavier
than a "fully laden shuttle" (think of it in terms of the orbiter
carrying the equivalent weight of a 747!!)

As for dumping fuel for emergency landings, the problem can hardly
be the weight on gear or runway -- after all, the thing has already
been taxiing around with a full load before it took off!   No, the
fuel dumping is done for a couple of reasons - to reduce the mass
that the aircraft brakes will have to slow down (sure, they *can*
handle a fully loaded 747 at takeoff speed in case of aborted takeoff,
but it doesn't do the brakes any good), and also to reduce the
amount of fuel that could be involved in any post-crash fire, if
the emergency landing ain't too smooth. The former reason is probably
the stronger reason, reduce the mass to reduce the braking effort
needed (which in turn reduces the chance of further damage from locked
brakes, blown tires, etc).

The 747+orbiter combo has landed at quite a few airports other than
KSC and Edwards -- indeed I don't think it can make the ferry trip
without refueling a couple of times along the way (the 747 can't take
on full fuel, and has a *lot* of extra drag from the orbiter).   I imagine
most airports handling heavy jets could handle shuttle landings --
given the precise navigation systems required for the one shot at
landing.