the future
ever wonder what it's going to be like
20 30 or even 40 years from now
hello
and welcome to future path
i'm amariko forrestery director of
external affairs at the nasa lewis
research center in cleveland ohio
in the future we all know our clothes
will change our hairstyles will change
and even the music we listen to will
change
but how will the technology that's being
developed today affect our lifestyles in
the future
for a long time nasa's been concerned
with developing aircraft that will fly
further higher and faster but more
recently our concern has changed to
flying aircraft with greater fuel
efficiency and protecting our air
quality
nasa is developing a propulsion system
which involves both the jet engine and
advanced propellers it's called the
advanced turboprop system and shown here
the advanced turboprop project combines
the efficiency of the propeller
with the power of the turbine
this technology base provides for the
future development of the single
rotation and counter rotation turboprop
propulsion systems
the idea is to reduce fuel consumption
in both military and commercial aircraft
the initial concept for the advanced
turboprop system
first came about in the mid-1970s due to
the opec oil embargo and the sharp rise
in fuel prices
the fuel burned in a 727 or 737 jet
aircraft can be reduced by as much as 50
with a propeller driven aircraft
advanced turboprop propellers are very
different from traditional propeller
designs
they are very highly swept and very thin
there are eight to ten blades rather
than a three or four blades that we are
used to seeing
we therefore get more power in a smaller
diameter
it allows us to fly faster up to 600
miles per hour and at a much higher
altitude
around 35 000 feet
the noise levels of this new turboprop
are much less than the traditional
propeller or turboprop aircraft
there have been three series of flight
tests in the advanced turboprop project
won the nasa ge boeing flight tests of
the counter-rotating unducted fan on a
b-727 aircraft
two the nasa lockheed prop band tests of
a single rotation advanced turboprop on
a gulfstream two aircraft and three the
ge mcdonald douglas tests on an md-80
aircraft
these tests verified the readiness of
the advanced turboprop project for
commercial engine development
another way nasa is helping the aviation
industry to a more efficient future
another form of a propulsion system is
the diesel engine
when you think of diesel engines you
probably think of certain types of cars
or heavy trucks barreling down the
highway
but technology developed by nasa is
currently creating breakthroughs in
aircraft diesel engines
nasa is also designing remarkable
improvements for diesel engines and
trucks
enthusiasm for the development of diesel
engines is reaching pre-world war two
levels
that's when diesel engine technology was
very popular for its endurance and
altitude records set on long distance
flights
although the war halted further
development of aircraft diesel engines
work on the engines continued again well
after the war
the united states army is developing and
designing diesel engines for helicopters
various industries throughout the world
are planning to develop aircraft diesel
and diesel engines used in heavy-duty
trucks are being improved upon by the
department of energy diesel engines are
primarily used when high power is needed
and fuel consumption and durability are
of concern trucks stationary power
plants large ships even tug boats use
diesel engines
a man who sees a bright future in diesel
technology is mr william wintucky
mr wintucky who has done much research
on aviation diesel is involved with a
number of projects at nasa lewis
research center aimed at improving
diesel engines
joint research is underway involving
nasa and the department of energy to
make diesel engines more fuel efficient
technology to redirect fuel exhaust back
into the engine could result in reduced
fuel consumption of long-haul trucks by
up to 30 percent
mr wintucky explains the difference
between diesel engines and gasoline
engines a
diesel engine is basically the same as a
gasoline engine except for the
combustion process
the difference in the combustion process
is that
as
the fuel is compressed by the piston
the temperature is raised
to a point where ignition
is started by the heat of compression
from the piston
in
the
gasoline engine
the combustion is controlled by a spark
plug
and ignition
is controlled when you want it started
by an electrical
impulse which discharges through the
spark plug
in the case of the diesel engine
when the fuel is raised to its auto
ignition temperature
the fuel ignites throughout the
combustion chamber
at the same time and therefore
the pressure rises very rapidly just
like an explosion and as a matter of
fact is an explosion
and that's why sometimes
when you hear a diesel engine going down
the street and it sounds like it's
knocking you are actually hearing the
explosions of the combustion process
because of the
explosions or very rapid pressure rises
in the diesel combustion chamber the
walls of the chamber have to be thicker
and also the bearings have to be larger
overall the engine must be much stronger
to design for the explosions
why develop better diesel engines and
why create one for aircraft
diesel fuel which is oil can be produced
from a wide variety of sources such as
of all things sunflower oil or peanut
oil
also diesel fuel is safer
because it does not ignite on its own
absence of an electrical ignition system
eliminated radio interference another
safety factor for aircraft diesels
the desire to use the fuel-efficient
diesel engine in aircraft is not new
interest in aircraft diesel engines goes
back as almost as far as internal
combustion engine gasoline engines
dating back to 1911.
the main reason
that
diesel engines were considered for
aircraft use very early on
was at that time
all of the gasoline engines were
carbureted
and one of the main problems that
aircraft had
was
icing
and
with diesel fuel since the fuel was
injected directly into the cylinder
there was no problem with carburetor
icing or ice forming in the carburetor
stopping the fuel flow and of course
stopping the engine
a second and almost important reason was
the fact that diesel fuel does not auto
ignite
which was a problem in the early days
of aircraft
auto ignition
is the process where the fuel ignites
spontaneously or without any external
source
in the case of gasoline gasoline
vaporizes very easily
and
the vapors are very combustible
with diesel fuel diesel fuel does not
vaporize very easily and stays as a
liquid so therefore it is a much safer
fuel to use
the diesel or compression ignition
engine was first designed by dr rudolph
diesel of germany
by 1897 the first commercially practical
diesel was put into use in the form of
an industrial engine
about 1910 the heavy slow speed diesel
engines were replaced with higher speed
lightweight engines which provided a
major step toward aviation diesel use
in nineteen thirty one the nine cylinder
packard diesel built in the u.s set and
still holds the world diesel flight
endurance record of 84 hours and 35
minutes without refueling
credit for originating the diesel
aircraft engine is given to germany's dr
hugo junkers
dr junkers was interested in development
of
a diesel engine
to power
commercial
aircraft
at the time
there were no transatlantic flights
because
gasoline-powered aircraft could not
carry enough fuel to cross the atlantic
and still have enough
room left for payload and the diesel
engine
was the only engine at that time known
to have the fuel efficiency that would
allow
transatlantic flight and still have room
to carry either mail or payload
so in conjunction with lufthansa
the junkers joomla
engine was developed
and installed on
a number of flying votes which lufthansa
entered into transatlantic service from
the azores to south america in 1936.
the jumo continued operating until the
outbreak of world war ii when production
turned to the more easily designed and
constructed gasoline engines from
military aircraft
the british developed the last major
aircraft diesel engine which used a
turbine to give it more power
mr wintucky gives us some insight into
the most fuel-efficient engine ever
flown british napier nomad engine was
very unique
it was really a
very high performance turbocharger
in that
the exhaust gases from the engine
the diesel portion
were ducted into
a fan-like turbine
which then drove the compressor
which
compressed air
and put it into the inlet of the diesel
engine
this raised the
overall pressure in the engine and
allowed it to produce more power for
the given size of engine that it was
and in many cases
engines will produce two three and even
four times as much power when
turbocharged versus when they just have
a carburetor on them as would be in your
normal automobile engine
turbocharged diesel engines for aircraft
are making a comeback
nasa research has inspired the us army
to develop the technology to use diesel
engines in helicopters
early in the 1980s the army did a number
of studies
in looking at
engines for light helicopter use
and they found
that
through the use of a very highly
turbocharged diesel engine they could
get an increase of up to 50 percent in
range or a payload that a helicopter
could carry
and since
for the army
fuel represents up to 70 percent
of the amount of supplies that has to be
transported to the battlefield
a 50
savings in fuel or a 50
increase in payload
represents a tremendous savings to the
army and a reduction in a logistics
problem so the army was very much
interested in
the use of the diesel engine to
lower
part of its fuel requirements
the army really took the expertise that
nasa had developed
during the time
that it was looking at the aircraft
diesel engine
and is now using this expertise in its
own program the engine being developed
by the army for helicopters is expected
to be operating by the mid 1990s
and work is being done to develop
materials and lubricants able to
withstand the high temperatures high
speed and high pressure of an aircraft
diesel engine
the
oil that you use in your car
runs
at the most
about 350 degrees fahrenheit
whereas
in the engine
for
the helicopter we're talking about
running as high as 800 degrees
fahrenheit
there is no
oil now
commercially available that will
withstand these temperatures
there are lubricants
that can operate at these temperatures
but they cost thousands of dollars and
the goal of our program
is to
develop new lubricants that will be
economically feasible
and
operate within the temperature
limitations that are required to produce
the power for this engine
it is hoped the united states army's
efforts with diesel technology will
result in a safer more fuel efficient
and economical helicopter fleet
the diesel engine's low fuel consumption
feature is valuable to countries such as
italy and japan where fuel is very
costly and also to the ussr where
long-range flights abound
decades ago scientists were able to see
the promise of diesel engines in
aircraft
the previous work is the firm foundation
on which today's research can stand
research that nasa and people such as mr
wintucky believe is important and could
result in 21st century aircraft diesel
engines
now let's talk about another engine
you've probably never even heard of the
sterling engine
as part of the work being done in
today's dynamic aerospace industry nasa
lewis research center is further
developing a rather remarkable engine
which was invented surprisingly way back
in 1816
named after robert sterling its inventor
the sterling engine very well could be
the most exciting and efficient new type
of energy conversion device in space
within the foreseeable future already
the engine has been developed and tested
successfully as an automotive engine
using less fuel than the car engines we
use now
and the sterling engine can use a
variety of fuels gasoline diesel fuel
alcohol kerosene and others
during this report though we will
explore this fascinating engine in its
possible uses in space
logically we begin by asking how does
the sterling engine work
simply put the engine works because of a
difference in temperature
one end is kept hot while the other is
cold
within the engine a displacer piston
moves gas from the hot end to the cold
end and back again
as that gas moves its pressure changes
when the pressure is high the gas pushes
against a power piston causing an output
of energy
since the heat input is supplied
externally anything that will burn or
make heat such as solar or nuclear power
fossil or gaseous fuels or even garbage
will make the sterling engine run
nasa is working to develop materials
that can withstand extremely high
temperatures to be used in the
construction of the sterling engine
there are two kinds of sterling engines
the kinematic and the free piston
the free piston shows the most promise
as a source of electric power in space
this concept is relatively new
approximately 25 years old
in their basic form both types have a
piston and a displacer
in the kinematic engine the piston and
displacer are connected to other parts
of the engine
but in the free piston the piston and
displacer are not physically connected
to anything and move solely by forces
and pressures within the engine
at nasa's sterling engine project office
jim dudenhofer special project manager
had this to say about the sterling
suitability for use in space
so we have gas bearings
to eliminate friction and wear
we have a totally hermetically sealed
unit which helps us with gas leakage and
permeation in the long term bear in mind
we're talking about an engine when we
talk about space that must live out
there without a mechanic for anywhere
from seven to twenty years
and so long life and and good
maintainability
uh are essential for a space power
engine
nasa lewis research center continues its
work with the sterling engine as part of
a project called the civil space
technology initiative
the purpose is to develop various
technologies for future use in space
until about 1985 there were free piston
sterling machines that could generate
only a maximum of three kilowatts of
electricity
nasa in trying to increase power output
developed with mechanical technology
incorporated a 25 kilowatt electric
machine
now nasa is trying to find out how much
larger sterling engines can be made
initial studies indicate power levels as
high as 500 kilowatts per machine and
possibly even higher
and finally why develop the sterling
engine now when already power has been
generated in space in other ways for
years
jim dudenha for answers space technology
is growing by leaps and bounds and
instead of needing hundreds of watts
in space we are now are going to be
we're on the threshold of needing
millions of watts
if we're going to colonize mars if we're
going to colonize the moon if we're
going to manufacture in space
we need tremendous amounts of electrical
power
photovoltaics simply become too large
the great big solar panels that we're
all accustomed to seeing simply become
too large they're too difficult to move
they have some limitations in polar
orbits because of the the problems
encountered with the van allen radiation
belts
solar dynamic machines of which sterling
is one
can operate any place that there is a
source of heat be it the the sun
be it nuclear
a sterling engine wants its supplied
heat can function
and it can produce large amounts of of
electrical power output in a relatively
small and lightweight package
and that's our purpose for being
involved in this type of technology
development work the amazing sterling
engine one of the most efficient heat
engines made and just one of the many
technologies being developed today at
nasa lewis research center
now that we have a background on
understanding how the sterling engine
works
let's view a short animated piece on the
development of the sterling engine for
its use in space
the free piston sterling engine effort
is directed at high efficiency
long life and a high specific power
to meet nasa's needs for future space
missions
the successful tests of the 25 kilowatt
space power demonstrator engine at 650
degrees k in 1985
completed phase one
phase two of the three-phase sterling
program is now underway
leading to the design fabrication and
testing of a 1050 degree kelvin super
alloy sterling engine
this is one of several conceptual
designs
the successful development of the 1050k
experimental sterling engine provides a
low cost basis for the low risk future
development of the phase three
refractory alloy 1300k engine
it will also provide a variable
alternative power conversion system for
an early flight demonstration of the s p
100 nuclear space power reactor
the performance objectives of a typical
single cylinder design are
alternator output 25 kilowatts of
electricity
engine efficiency
30 percent
inlet temperature
1050 degrees kelvin
outlet temperature
525 degrees kelvin
working fluid
helium
engine alternator frequency
90 hertz
specific mass
6.4 kilograms per kilowatt of
electricity
operational life
over seven years
with lessons learned in the 650 phase 1
engine program the super alloy phase 2
engine is being confidently designed for
high performance and long life with
current nickel base super alloys
the free piston sterling engine achieves
its high performance in part due to its
simplicity of design and operation
its major features are
the heat exchanger assembly which will
have only 40 heater cooler modules to
significantly reduce the number of
welded tube joints
the displacer one of three moving parts
is a five kilogram piston floating on a
film of helium
and shuttles the working fluid from the
hot expansion space to the coal
compression space and vice versa
the reciprocating action of the 12
kilogram power piston caused by the
working fluid produces electrical power
in the linear alternator
the 12 kilogram balance piston
oscillates to fully counteract the
combined vibrations of the displacer and
power pistons
alternate engine designs employ opposed
sets of pistons synchronized to
eliminate the need for a balanced piston
magnets in the power piston oscillate
through the stator laminations to
produce alternating current
the pressure volume diagram shows the
cyclic variation of pressure and volume
in the working space between the power
and displacer pistons
the area enclosed by this diagram is
indicative of the engine's thermodynamic
power
the following computer-generated
animation shows relative motions of the
three pistons
for clarity their speeds have been
greatly reduced from the normal 90
cycles per second operating frequency
we hope you've enjoyed our program i'm
america forester hoping you'll walk with
me again along the future path at the
nasa lewis research center in cleveland
ohio
so
oh
so
too
sink rate is now uh 70 feet per second
here are down
one mile from the runway
uh 86 feet
gear down and locked and we have
touchdown at mission elapsed time seven
days
one hour
38 minutes
and 50 seconds
you