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Stone, Paul (ed.) / Wisconsin engineer
Volume 90, No. 4 (April 1986)

Szymanski, John
Transatmospheric vehicles: alternative to the space shuttle?,   p. 6

Page 6

Transatmospheric Vehicles
Alternative to the space shuttle?
by John Szymanski
In wake of the space shuttle disaster,
the vulnerability of the program has been
exposed. Investigating the crash, redesign-
ing the solid rocket boosters, and restruc-
turing some of the management in Nation-
al Aeronautics and Space Administration
(NASA) is going to set the program back a
year to a year and a half. But there is an
alternative to the shuttle which has yet to
be developed: the transatmospheric vehi-
cle (TAV).
The TAV is a spaceplane capable of
taking off from an ordinary runway, boost-
ing itself out of the atmosphere into a low
space orbit without jettisoning away any of
its parts, then landing back on an ordinary
runway. Flying speeds of various TAVs
will range from Mach 5 to Mach 25 (Mach
N being N times the speed of sound).
Initially the military will be using the craft
for sending payloads into orbit, but further
development will render it useful to air
travelers. The estimated flying time be-
tween London and Sydney, Australia
traveling at Mach 25 would be 67 minutes,
but more realistic craft speeds are pegged
between Mach 5 and Mach 10. These
speeds would yield a flight time from L.A.
to Tokyo of around two hours. However,
the TAV will not be ready for commercial
use until the military is able to procure a
satisfactory working prototype, which is
expected around the year 2000.
In March of 1985, President Reagan
signed an order mandating the develop-
ment of the TAV. Currently the program is
in Phase II, which is the testing of compo-
nents of the craft. Phase II should be
completed by 1988. If Phase II is a
success, Phase Ill, consisting of the build-
ing and testing of a test plane, will be
initiated  and  should  last through
(continued on 13)
Ultrafiltration of Milk
Progress in Wisconsin's cheese industry
by David Chew
Everyone in Wisconsin is familiar with
the  license  plate logo  that reads,
"America's   Dairyland."  Wisconsin
produces 30 percent of the nation's
cheese; it's a very big business here.
Chemical   engineering  professor
Charles Hill has worked on research in the
dairy industry since 1967, and is now a
member of the Cheese Research Institute.
Currently, he is working on an ultrafiltra-
tion process which could revolutionize the
cheese industry, both on the farm and in
the factory.
For every pound of cheese made, nine
pounds of whey are produced. Whey is
waste water which contains solids, mainly
in the form of lactose and protein. Because
of its high biological oxygen demand,
whey is difficult and expensive to dispose
of; this represents a major cost to cheese
manufacturers. Professor Hill, along with
Clyde Amundson and former graduate
student Anne Slack (both of the UW
Department  of  Food   Science)  has
proposed a method of ultrafiltering milk
on the farm before it is transported to the
cheese manufacturer. This method would
eliminate much of the unwanted whey
that is produced.
Ultrafiltration is a separation process
utilizing a semi-permeable membrane
which allows low molecular weight
materials to pass through while larger
molecules are trapped behind. In the
ultrafiltration process, pressurized milk is
forced over a polymer membrane laid out
in various configurations such as a flat
plate, a 1-inch diameter open tube, many
small diameter (100 microns) tubes, or
even a spiral-wound membrane which is
rolled much like a jelly roll.
Unlike reverse osmosis, in which only
water permeates the membrane, ultrafiltra-
tion also allows the low molecular weight
solutes such as lactose and mineral nutri-
ents to pass through, leaving behind a
highly concentrated, protein-enriched liq-
uid (24% solids, 9.8% protein, and 11.5%
fat). The permeate is a clear liquid con-
taining no fat and a negligible amount of
Anne Slack actually used two different
membranes in her graduate work. One
had a molecular weight cutoff of 8000 -
10,000 grams per mole, and the other had
a cutoff of 3000 - 5000.
Ultrafiltration of the whole milk on the
farm as the cows are being milked has
been proposed. There are many advan-
tages to this method for both the farmer
and the manufacturer.
(continued on 17)
Graduate student Anne Slack checks the filtering
Wisconsin Engineer, April 1986
The TAV could travel from
L.A. to Tokyo in about two

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