Space Forum / Shuttle / May 2006

largely because of the terrible weather at the russian site. little
time at outdoor pad. any problems just bring it back on the rails and
repair/

probably a better system than the us with shuttles sitting outdoors for
much of their life waiting to launch.

this has caused corrosion that likely wouldnt of occured with the
vehicle in a clean room.

much nicer for workers no mosquitoes:)_

plus is a launch pad accident takes out the pad theres less to lose
since a lot more equiptement is back at the VAB equivalent.

<snip>

I don't claim to be an expert on this stuff ... but I can offer a few
suggestions ...

First, the current setup for assembly of the STS is left over from the
assembly of the Saturn V. That involved the assembly of a 363-foot high
monster. Also, they decided to not build a gantry for the vehicles at pads
39A and 39B, but to carry the gantry along with the Saturn V on the mobile
launch platform out to the pad. I don't think they pursued a "horizontal
transport/elevate to vertical at the pad" option for very long, if at all.

Also, the road from the VAB to the pad is not "hardened," in the paved
sense. The load of the Saturn V, along with the gantry and the mobile launch
platform, was too much for a paved road to handle. The only option that they
could come up with was crushed rock (I'm not sure how thick, but I'd say a
couple of meters or so, at least). So I'm guessing that the most stable
option to traverse that would be a tracked vehicle.

I daresay that others with more knowledge than I about this will correct me
if I'm wrong, but I think this is where the rationale came from. When STS
came along, it was cheaper to modify the existing infrastructure than to
build an all new setup (or at least that was how it was sold).

See if you can track down a copy of the Murray and Cox book
(http://www.apollostory.com/) if you'd like some background into where the
idea for the VAB/transport system originated.

Hope this helps.

James

Early U.S. missiles like Redstone, Atlas, Thor, and Jupiter were, just
like the USSR's R-7, designed to be transported and stored horizontally

and erected to vertical shortly before launch.  When upper stages were
first added to the U.S. missiles, most systems were designed for
vertical erection of the upper stage on top of the already-erected
missile-based lower stage or stages (the first Thor-Agenas being one
exception).  It could be that such an approach allowed the missile
portion of the launch vehicle to be erected and checked out, more or
less unchanged from before as if it were still a missile, independently

of the upper stage.  It might be that the U.S. had so many available
launch pads at Canaveral and Vandenberg while the Soviets had
fewer, larger, more-costly pads that had to be used more efficiently.
It could be that the Soviets initially began performing space launches
from an active ICBM launch pad, which drove them to use the more
mobile, rapid response systems already in place, while the U.S.
only performed space launches from modified missile *test* pads
that had never been designed to handle the deployed missile erection
systems.  The Russian wedding of its rail-system to missile transport,
compared to the U.S. use of trailered road-based transport systems,
may have had an effect.  Launch site weather may have played a role.

Another possibility is that while the U.S. got many of the V-2
structures, propulsion, and guidance experts out of Germany at the
end of World War 2, Russia got most of the people who were best
at field deployment systems, etc.  V-2 missiles were exceptionally
mobile for their time.

Once the U.S. started adding solid rocket motors to the launch
vehicles,
the vertical integration method became the preferred approach because
of vehicle mass.  Russian rockets are transported and erected unfueled.

U.S. solid rocket motors are, in effect, fully fueled and weigh more.
An erector capable of handling a space shuttle stack, for example,
would have to be as massive as the structural framing of a skyscraper.

- Ed Kyle

The "Moonport" history provides some details of the horizontal
versus vertical decision for Saturn.

Studies showed that for low launch rates, the existing fixed pad
integration methods offered the lowest cost solution.  For higher
launch rates, horizontal integration and transport provided the
lowest cost.

"http://www.hq.nasa.gov/office/pao/History/SP-4204/ch4-5.html"

So, of course, NASA went with vertical integration and transport!

"http://www.hq.nasa.gov/office/pao/History/SP-4204/ch4-9.html"

The primary reasoning against horizontal integration seemed to
be that it made it more likely that workers could damage the
launch vehicle (recent shuttle orbiter processing accidents
seems an example of what the they were thinking).  The real
reason might have been simply that NASA (especially MSFC)
knew, from experience, that vertical processing worked.

- Ed Kyle