welcome to future path I'm a Mariko for
Astari the director of External Affairs
at the NASA Lewis Research Center in
this series we are exploring research
and technology programs that may affect
our lives this show deals with the
present and the future in a little while
we'll see how an advanced propeller
aircraft engine now under test may
replace conventional jet engines but
first let's take a look at the space
station here at Lois we have had an
ongoing program to design power systems
for future spacecraft before Lewis began
to work on a power system for the space
station however many years of research
went by throughout the 30-year history
of space exploration there has been an
evolution in our understanding and use
of space
we began with exploration pioneering
kind of missions we've demonstrated some
initial space operational capability
with the shuttle we now want to make
space a place where we live and work
permanently so space station we believe
is the next logical step in that
evolutionary process the next logical
step we have visited space for short
periods we now have the capability and
resources to make it a place to go to
stay permanently a place where we go to
work and to do useful tasks a space
station is a logical place in which to
do this
the main horizontal keel will have solar
powered electrical generating systems
and pressurize crew and laboratory
modules the space station is being
designed to serve a variety of users
many experimenters have been identified
these will be earth viewing space
viewing experiments many microgravity
experiments Space Station will be used
for assembly of large structures
servicing of satellites and other
payloads and as a transportation node in
the sense that payloads would be taken
off of the space shuttle and put on to
some other rocket to go into
interplanetary space or to high Earth
orbit space station will be a research
laboratory to conduct science and to
develop new technologies a permanent
Observatory enabling us to look down at
earth and up at the stars the station
will be a servicing manufacturing and
assembly plant as well as a storage
depot and a staging base there are many
other uses the bottom line is that space
station will be a multi-purpose facility
very much unlike the spacecraft that
nASA has designed in the past which were
designed for essentially one mission
space station will be very different it
will be multi-purpose and it will be
very long-lived compared with previous
spacecraft in the sense that space
station is designed for approximately a
30-year lifetime you contrast that with
single purpose satellites which might be
designed for a few years at most the
role of Lewis Research Center in the
space station program is to design the
electrical power generating conditioning
and storage systems power the use of
power for civilization is a measure of
its development if you chart the usage
of power on earth you find that the more
advanced societies use more and more
electric power the less advanced you are
the less you use in space we've been
absolutely primitive in the first 25
years of the space program scarcely
using more than 10 kilowatts put that in
perspective your house uses about 25
kilowatts so we're limited in what we
can do
and that means we can't really flex our
muscles in space we can't utilize it we
can't understand it well so we're power
poor and so we can't explore power is
vital the space station without power
the station could not work other space
missions use a small amount of power in
comparison to space stations needs
communication satellites use up to about
10 kilowatts of power previously the
largest user of power in near space was
Skylab it used about 15 kilowatts of
electricity space station may use more
than 20 times that or nearly 300
kilowatts to make that much electricity
space station will eventually rely on
hybrid or combination of both solar
cells and a solar dynamic system the
system to be used first is a solar cell
system solar cells in large panels or
solar arrays collect sunshine and
convert it directly into electricity the
hardware to be launched first by the
shuttle will be solar panels they've
been used to power spacecraft now
throughout the history of the space
program and we have great confidence
that they will work that we will be able
to manufacture test and verify their
performance to a very high level of
confidence early solar array panels are
about 7% efficient but now new improved
solar arrays run at about 10% efficiency
solar panels have a drawback to produce
about 300 kilowatts 30,000 square feet
of panels are needed that's a lot at
first to complete solar panels will be
orbited for Space Station each unit will
be about 110 feet long by 33 feet wide
another problem created by the large
size of the panel's
is atmospheric drag even though space
station will orbit at about 250 miles
there are enough atoms of air at that
altitude to impact on the panel's and
cause the station to slow down ever
so slightly so the station must be
periodically boosted back into its
original orbit NASA is designing a
system with a smaller area to reduce
atmospheric drag this system is the
solar dynamic system solar dynamic
system uses a concentrating mirror to
collect and focus the sun's energy into
a receiver that accepts that energy in
the form of heat that's very different
than solar cells which converts sunlight
directly into electricity solar dynamic
systems operate on heat use that heat to
heat a fluid that runs through a turbine
causing it to rotate the turbine of
course is attached to a generator which
actually converts the mechanical energy
of rotation into electrical energy and
that circulating fluid is then reused in
a closed system so solar dynamic systems
take sunlight convert it to heat that is
transformed into mechanical energy and
then finally into electrical energy that
sounds like a complex process but the
overall system efficiency there is
greater than it is for photovoltaic
devices besides having a smaller drag
area the solar dynamic system is more
than 15 percent efficient and NASA is
looking at other systems which are more
than 30 percent efficient they use
different engines to drive generators
but what do you do if there's no
sunlight communication satellites orbit
at an altitude of 22,000 miles these
satellites rely on solar cells and
storage batteries for power batteries
supply electricity to the craft when it
is in Earth's shadow at 22,000 miles
those satellites rarely pass into the
shadow of Earth in low-earth orbit space
station will be in the shadow of earth
for about half of each 90-minute orbit
the initial space station relying
exclusively on solar cells will require
much larger batteries than previously
used in space but as solar
amic power systems are added energy
storage will be a different matter
altogether
in the case of the solar dynamic system
that energy is stored in the form of
heat the leading contender for storing
that energy that heat energy now is some
type of salt a phase change material
that converts from a solid to a liquid
and by virtue of doing that is able to
store much greater amounts of energy
these salts or phase change materials
are not like common table salt the
special salts melt at a very high
temperature when space station passes
into the Earth's shadow sunlight will no
longer be focused on to the receiving
cavity of the solar mirror the salts
will slowly cool and change from a
liquid to a solid giving off large
amounts of heat to drive generators
space station power systems will make a
lot of electricity initially more than
75 kilowatts and more later how will all
this electricity be used probably the
users will be the largest consumers of
power there is a class of experiments
called materials processing that are
estimating their needs and the tens of
kilowatts by far in a way that will be
the single largest user of power
we also lump power into another category
called housekeeping by this we mean
electrical energy required to operate
the environmental control and life
support system for regenerating the air
and water on board the space station
housekeeping also includes lights
preparing food in the galley
entertainment devices and so forth
personal care devices that the
astronauts might use and communications
and computer systems all of that we lump
into housekeeping power and it will be
not as large a user of electrical energy
but it since we lump so much into that
single category it looks like a big
number the shuttle will first launch
space station elements
the mid-1990s shuttle will be used in
the assembly and check out of the
station a number of launches will be
needed and there will be various phases
of capability that the station will go
through it will be unmanned at first
then mant ended within a year and a half
beyond that the station is to be
permanently manned the ultimate benefit
of space station to mankind will be to
extend man's capability to explore the
solar system space station will provide
the necessary first step for future
manned missions in space a permanent
lunar base a manned mission to Mars a
manned survey of the asteroids space
station will enable the staging of
future unmanned missions to the planets
with the possibility of sample returns
but most importantly Space Station will
be the next logical step
now let's turn from the space station to
a story about how propellers may again
be back on passenger planes in the late
1950s jet aircraft entered into
commercial service and essentially
replaced the slower but more efficient
propeller driven aircraft then in the
late 1973 the oil embargo hit NASA was
mandated to explore all technologies
that could significantly reduce
commercial aircraft fuel consumption the
Lewis Research Center responded with the
advanced turboprop program what might
look like a step backwards is actually
two giant steps forward on the future
path of advanced aircraft engine
since 1941 the Lewis Research Center has
developed an international reputation
for its research on jet propulsion
systems however in 1977 the researchers
at Louis began to take a new look at the
propeller their challenge was to combine
the efficiency of the propeller with the
power of the turbine engine what has
evolved is ATP the advanced turboprop
project Keith severs manager of the NASA
advanced turboprop project office at the
Lewis Research Center back after World
War two jets for the thing the coming
thing her powers were very efficient in
those days but they couldn't go fast it
couldn't go to high altitudes and quite
frankly they were not jazzy like jet
engines and which gave way then to
turbofan engines and high bypass ratio
engines and when fuel was chief people
didn't worry much about it ten cents a
gallon as long as they get speed high
altitude capability which the air
transport system required propellers
just kind of withered on the vine for 20
or 30 years the Arab oil embargo of the
early 70s not only hit American
consumers at the corner gas station but
was also reflected at the airline ticket
counter due to the soaring price of jet
fuel in 1973 the price of a gallon of
jet fuel was 12 cents and represented
one-quarter of the direct operating cost
of the jet in 1981 the cost of jet fuel
was over a dollar eight cents a gallon
with the rising fuel prices a fuel
efficient propeller engine again became
the object of an aeronautical propulsion
research effort
the researchers objectives were to
develop a powerplant that would be fuel
efficient dew point eight mach cruise at
35,000 feet operate at a reduced noise
level well these propellers look a lot
different there are very highly swept
they're very thin compared to old
propellers
and the thing that hits you first is
their eight to ten blades on these would
rather than three or four is that you've
been accustomed to in the past and what
the sweep doesn't in the propeller and a
fitness is is to reduce the drag losses
at the higher tip speeds and higher Mach
numbers also helps to reduce the source
noise of the propellers the higher
blade count and we've loaded these
blades up much higher than old fellers
so we get a lot more power at a lot
smaller diameter and this saves weight
on the propeller and I say it's weight
on the engine and it also packages
better on the aircraft earlier two turbo
props were limited both in horsepower
and in flight speed mainly because of
the compressibility effects that occur
at the propeller tips with the recent
advances in computer design technology
we are now able to optimize the blade
shape to minimize the compressibility
effects occurring at the blade tips
allowing the planes to fly faster up to
six hundred miles an hour and at higher
altitudes up to thirty five thousand
feet as you approach the speed of sound
you run into a problem where the
apparent pressure that you're trying to
push through suddenly takes a quantum
leap and because the blades are very
large in diameter to thirteen feet in
diameter the tip speed is upwards of 800
feet per second which is just under Mach
1 or the speed of sound as you try to
push through that Mach 1 range you run
into this compressibility factor it's
almost like running into a brick wall
with the blade blade construction is now
a composite type arrangement where you
have a metallic leading edge such as
aluminum and a graphite epoxy resign'd
internal construction that allows the
blades to be very lightweight and
because they're lighter weight minimizes
the centrifugal stresses that occur when
the propeller system is
dated at 12,000 rpm ultimate goal is to
save fuel commercial aircraft and also
military aircraft were it can be applied
and this fuel saving is very dramatic
compared to the fuel burn that aircraft
have today such as a 727 737 that type
of air cream aircraft a prop van driven
airplane can do the same mission that
like forty to fifty percent of the fuel
that they use today if you look at just
the u.s. fleet existing today for medium
to short range aircraft I'm talking 727
737s dc9 md-80s those aircraft in a
typical year burn about five billion
gallons of fuel if these aircraft were
equipped with pop fans they could do the
same mission they're dirty today and
save two to two and a half billion
gallons of fuel per year
propeller-driven airplanes have
traditionally been noisy advanced
turboprop researchers are tackling the
problem of trying to build a turboprop
to rival the relative quiet and
smoothness of the jet well we've had to
look at the entire aircraft as a system
we didn't look just at sticking a new
widget call of profiting on them better
look at what to do to do to the rest of
the aircraft and particularly we're
concern about passenger comfort it
doesn't matter how much fuel was saved
if the people don't like it or they're
uncomfortable sound vibration so part of
our project goal is to to make sure that
people have the same comfort that
they're used to on today's wide-body
aircraft in addition we're concerned
about community noise these things are
allowed and we have to provide the
technology so we think it will
listing for 37 states we regulate
by around airports and communities
most of the time we really don't even
know what's running inside the cockpit
it's that quiet and we're only what 15
feet away from after several years of
wind tunnel and static engine testing a
full flight test of the advanced
propeller system was held on May 19 1987
at Lockheed Georgia company in Marietta
Georgia so far operation has been very
good everything is about as predicted
that the engineers had predicted
from their initial assessment of the
program we haven't really had any big
surprises I should say when you pull the
prop fan in and add power to it the
pilot really knows it but there again
this airplane wasn't really designed to
fly with an engine out on a on the left
wing
but again what our engineers predicted
is pretty much what's happening with the
airplane so I'd have to say so far it
looks good so far it looks very good if
all goes to plan prop fans will probably
be fitted on short to medium range
aircraft we hope to have as a part of
the project goal to have the technology
in hand by the end of 1980s so that
industry the engine people the aircraft
people can make marketing decisions
because it's a involves a lot of private
capital that's a make sure breaks
they're companies so the way things are
proceeding right now it looks like
Boeing and McDonnell Douglas are aiming
for new aircraft injuries or with the
prop fans and say the 1991 92 93
timeframe
the advanced turboprop program that you
just saw will help maintain the US
aircraft industry in a dominant world
leadership position well we've nearly
come to the end of our show but before
we go let's watch this NASA Lewis
Research Center overview this segment
will show you some of the high-tech
facilities and people who make it
possible for Louis to accomplish its
mission to develop advanced technology
for high priority national needs
thank you for spending some time with us
please stop by and see the many displays
and programs at the Visitor Center here
at Lois we are located near Hopkins
International Airport in Cleveland Ohio
admission is free and we are open every
day until next time then this is a
Mariko forest area saying goodbye