INVISIBLE BOMBER - SECRETS OF THE PLANE THAT RADAR CAN'T SEE

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP92T00277R000500040024-2
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 6
• Document Creation Date: December 27, 2016
• Document Release Date: March 13, 2012
• Sequence Number: 24
• Content Type: OPEN SOURCE

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Invisible
bomber
-secrets of the plane
that radar can t see
Airmen call ?hem "stealth"
planes. To enemy radar, they
can look like hummingbirds
By JIM SCHEFTER
ILLUSTRATION RY DEAN ELLIS
Shaped like a broad, flat wing with only a smoothly blend-
ed windscreen revealing its cockpit, the bomber skimmed
across barren polar terrain at nearly 600 mph. Barely 400
feet below, ice floes vibrated to the roar of its concealed jet
engines. The early-warning radar fence lay behind. its
operators unaware that the first line of defense had al-
ready been penetrated.
More radar waited ahead. [lugging the terrain to take
full advantage of hills and valleys, the flying wing crossed
Continued
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Ample window area on all side:> of house is one advantage of
HGE houses. This is southwest corner of the Heyd house.
reached 87 degrees F and the solarium rose to equal that,
the living areas of the house ranged from 71 to 74, without
auxiliary cooling. Certainly the outer shell, which shades
the living area from the sun, contributed to this. But the
cooling tubes, a standard feature of double-shell houses in
some climates, didn't seem to help much. In cooling mode,
hot air is supposed to rise from the solarium and exit
through attic vents, pulling fresh air that has been cooled
and dehumidified by earth contact into the envelope
through the cooling tubes. During part of the Mastin tests,
air flow was in the wrong direction: It flowed from the
house, through the cooling tubes, and out what was sup-
posed to be the inlet.
(Actually, the Mastin house doesn't present much of a
cooling challenge. It's about a mile from the Atlantic, and
prevailing southwest winds bathe it in cool ocean air on
most summer afternoons.)
After analyzing all the data collected, the Brookhaven
team reached this conclusion: "The low energy needs of the
Mastin house are attributable mainly to the excellent in-
sulative value of its double shell." If cost were a simple
overriding consideration, the report continues, "it would
be difficult to rationalize the double envelope's use over
the super-insulated house."
Super-insulated houses IPS, May '811 are exactly what
the name implies. They are constructed to include an enor-
mous amount of insulation. They conserve heat so well
that internal heat gain -from people and appliancesis
nearly enough to carry the house, even in a severely cold
climate. They rely on solar heat very little, and hence have
small windows, even on the south, since windows can be a
large source of heat loss.
Hybridization
But, Mastin decided, why not have the best of both
worlds'? His current designs blend many aspects of a super-
insulated house with some vestiges of the double-shell de-
sign. He calls the result a Hybrid Geotempered Envelope
~HGEI.
On a lovely wooded lot south of Boston, builder Robert
Green is just completing an HGE house for Robert and
Nina Heyd (see photo). Gary and Kathy Brennan and their
five children have just moved into another near Little
Compton, R.I. Both have solariums, but there's no air ple-
num forming a loop around these houses. Instead, a ther-
mostaticallycontrolled fan takes hot air from the top of the
solarium and delivers it through ducts to the basement.
The attic, foundation, and the north, east, and west
walls of these houses are super-insulated (see diagram).
The north, east, and west windows, however, look much
like the north windows in Mastin's own house: two sets of
double-glazed units. There is an air plenum at each win-
dow,but it's only as wide as the window and ends at the top
(which tends to comfort fire inspectors). It does, however,
run all the way down to the basement. "The true effective-
ness of the double-shell design is in reducing heat. loss
through glass," Martin says. "When the air between the
windows is colder than the air in the basement, it's going
to drop and displace the warmer air there, which will rise.
"The plenum also reduces infiltration," he points out..
"Yet when you need ventilation, you can open an interior
window and get it, without a blast of cold air." This miti-
gates the need for an air-to-air heat exchanger IPS, Jan.l>
which super-insulated houses often require. And since the
windows aren't horrible heat losers, HGE houses can have
a good many, even on the north side.
Mastin is not alone in modifying the double-shell con-
cept. In fact, a Pennsylvania designer, Christopher Shipp
(R.D. 1, Box 331D, West Grove, Pa. 19390), has come up
with an almost identical design, including both super-in-
sulated walls and double windows with air plenums con-
nected to the crawl space or basement. Shipp is also doing
variations of the double-shell house that are closer to the
original concept, but using fans to force the air flow (see
diagram). At least, he intends that these houses use fans.
So far the owners of the house in our photo haven't in-
stalled the fans. "They only spent $60 on electricity to heat
the house last winter, so spending $200 on fans e~eems
needless," Shipp reports.
How do these hybrid designs compare in cost, perfor-
mance, and livability with super-insulated houses`?
"The best-performing houses anywhere are the super-
insulated houses," Mastin admits. "They are also the most
cost-effective to build. But their obvious shortcoming is
lack of light, views, and natural ventilation."
If you count the solarium as an extra expense (about the
same per square foot as the rest of the house), Martin's
HGE-type houses cost a good bit more to build than super-
insulated houses. "But if you compare the cost with that of
a super-insulated house with a sunspace," Martin says,
"the only cost increase is for the double windows and their
plenums- about $200 per window. And you don't have the
cost or nuisance of window insulation."
The auxiliary heat requirements for super-insulated
houses generally come out to be even less than what the
Brookhaven tests showed Martin's house to need. Prelim-
inary monitoring of one of Martin's HGE houses, in South-
ington, Conn., suggests that its heat needs are in the same
ballpark, though somewhat more than the most efficient
super-insulated houses. More such data will be forthcom-
ing. Martin spent the past summer modifying his own
house to make it more like the hybrid design (see opening
page). Now Brookhaven has brought back the instruments
and will remonitor the house this winter.
Just what type of house is the most livable is a highly
personal matter. "I didn't want a strictly solar house be-
cause Ididn't want to cut down all my trees," says Robert
Heyd, gesturing toward a stand of stately oaks to the south
of his house. "And I didn't want asuper-insulated ]zouse
without much window space."
The Brennans are delighted with the choice they made.
"I checked out everything," says Kathy. "I visited some
passive-solar houses with whole south-facing glass walls.
They turned into an oven during the day, then cooled off
just as fast at night. I checked out others that had a base-
ment full of rocks, and some with water drums in the liv-
ing room-that really turned me off. With all the other
designs I read about, it seemed we had to give up some-
thing. This was the only one that had everything." m
FEBRUARY 19133 I 59
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SR-71 Blackbird spy plane (left) is one of the e+~rliest
designs with anti-radar stealth concepts. Ablue-black
coating is thought to have radar-absorbing properties.
The engines blend smoothly with the wings, and
slanted tail fins minimize radar reflections. British Vul-
can bomber (above;) also has stealth features: Engines
are concealed within its triangular wing, unlike engine:;
on B-52s, which capture and reflect radar signals.
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Lear Fan 2100 prototype, made largely with graphite composites, is a commercial aircraft design that's almost invisible to radar.
out of the tundr, . llespite its size and speed, it created just
a flicker on glowing scopes. It was no more than a hum-
mingbird darting south.
But this bird, still a paper airplane that won't fly before
1987, will be no harmless little avian. The popular word
used to describe it masks the most secret U.S. technology
program in four decades:
Stealth.
This multi-billion-dollar development, already under
wuy in a classified and guarded Northrup Corp, facility
midway between two major Lo~> Angeles freeways, is
aimed at producing a new bomber that is virtually unde-
tectable by radar. A secondary effort to produce a modified
B-1 bomber with a low radar profile is under way at a
Rockwell International plant in nearby Palmdale.
And a third project, by the Lockheed Corp., already has
produced at least three prototype stealth fighters. Flying
from a secret field near Groom Lake, Nev., and from Eiel-
son AFB, Alaska, since 19i'9, two of these triangular-
shape craft have crashed, but. for reasons not connected to
their strange design. The third reportedly continues to fly
test missions in both extreme heat and cold.
Taken together, the Pentagon expects these f~utw?istic
aircraft to alter the balance of military power into the next
century.
How will abomber-size aircraft deceive radar that is
itself state of the art.'? What new technology is on the draw-
ing board to create a machine that will penetrate enemy
airspace with impunity?
Some answers are emerging from this highly classified
program. Others undoubtedly will remain among the na-
tion's most tightly kept secrets. Briefings on stealth tech-
nology, when authorized by the Air Force, are sketchy.
Even individuals allowed to talk insist that their names be
concealed.
Even so, it was possible to put together a filtered look at
how the best aeronautical engineers in the world are de-
signing stealth-type aircraft. Some of the picture, neces-
sarily, is informed speculation by experts. But much al-
ready is known.
Low-flying attack
'['he bomber, for instance, is being designed to Hy inter-
continental distances at low altitudes at about Mach 0.85.
"High-altitude attack is not a wise idea because it, gives
the enemy a longer time to look at you on the way in," one
observer said.
The Air Force itself discourages the word ?stealth." It
prefers the term "low observable" and calls Northrop's
project the ATB, or advanced-technology bomber.
"When you talk about stealth," a high-ranking Air
Force officer told me, "you're talking about the ability to
offset the enemy threat to your penetration."
To do that takes an aircraft with a unique shape, built
with materials and coatings that both absorb and deflect
radar signals. It takes innovative designs to conceal jet
engines within the aircraft body. And it takes a host of
new electronics gear aboard the craft to isolate and confuse
enemy radar.
But. the first step is designing the aircraft itself. Air
Force and industry officials stress that. reducing radar
cross section-the reflecting surface actually seen by ra-
dar-is the major factor in playing aerial hide-and-seek.
Cross section is measured in square meters, as seen head-
on by defense radars.
For instance, the ancient B-52 that remains our primary
intercontinental bomber has a massive radar cross section
of about 100 square meters. Its tall, vertical stabilizer and
heavy body make it an ideal radar target. Even worse, its
large wing-slung engine pods concentrate radar signals
and echo them back with brilliant clarity.
A shrinking target
Rockwell's original B-1, which Jimmy Carter refused tc
build, produced a radar image of just 10 square meters.
And the B-1B, now being reworked in a stealth version
that will fty in 1985, echoes a cross section of just a single
square meter.
That's a flashing alarm compared with the stealthy
bomber on Northrop's drawing boards. It reportedly will
have a radar cross section ofone-millionth of a square me-
ter. Ahummingbird is bigger.
Designers will achieve this strikingly small radar cross
section with a number of design innovations. For example,
sharp edges and abrupt angles, often seen on aircraft
wings and control surfaces, produce strong radar echoes.
So there will be none on the new planes. Northrop's bomb-
er will be glow-profile flying wing. (Significantly, Nor-
thrup also built the original B-49 Flying Wing, which first
flew in 1947.) Tomorrow's stealth bomber will take the
concept even further, expanding on the so-called blended-
body concept provided by Rockwell's B-1 ~ PS, May '77 ~. Its
wing-body leading edge will be smoothly rounded, and its
delta shape will integrate fuselage, cockpit, and wing into
a single flowing wedge. Engines will be buried inside the
body, not hung out as tempting radar targets.
Northrup engineers also are wrestling with designs for
the vertical stabilizer. Their first choice is to eliminate it
completely. If computer analyses point up handling prob-
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l~~~in stabibzer~. ~I'hev could b,~ c;mlcd inward to deflect
radar rather than echo it.
No information is available about overall size of this fly-
ing wing. But it is certain to be low-slung and squat, al-
most like a Frisbee or boomerang in proportions. All that
ccill mike radio' sighting more difficult. Yet nun?e is
needed.
l)nc~ solutum is to elin~in;iie nu~inl wberevcr possible.
l~;arty versions of radar-absorbing nntterials, prinuu?ily
carbon-and-fiberglass composites, were developed by
Rockwall for the llound Ihig missile. '['hat technology is
being adapted for the stealth bomber.
Kecent adc:uues by a number of laboratories, including
the Air 1~'urce Materials Laboratory at Wright Patterson
AI~ B, Ohio, have led to composite materials that are stron-
ger and lighter than steel ur titanirnn vet. do not reflect
radar waves. A black fiber-reinforced graphite skin is
reported to be the leading contender for Northrop's
bomber.
With current technology, materials that absorb soma.
electromagnetic radiation are bonded to stronger titani-
um. But Lockheed's super-secret stealth tighter is believed
to be made largely of N'ibuloy, a composite developed by
Ilmc ('hemir.~l ('o. I~~ibaloy includes glass fibers embedded
in plastic and is said to be strong enough without metal
backing to fin?m bath the fighter's skin and its main struc-
tural nu~mhcrs.
'I'hc result is a 2(1,1100-pound fighter not only stealthy,
but small ;uul light enough to be carried inside a C-5A
h?a nsport .
:end the Air l~'orce is heavily committed to developing
even better carbon composites. 'That leaves the stealth-
`With front-facing air intakes,
that metal echoes radar like a
beacon. But the new bomber will
have concealed intakes, mounted
flush beneath the flying wing ~~
bomber designers to consider their]et engines, which can't
eliminate nu~tal.
"J el-engine intakes .u?e high-visibility items for radar,,,
one aeronautical expert told nu', "'To get enough air into an
engine, you need big compressor sections up fi?ont. They're
very balanced, built to close tolerances, and made of heavy
nu~lal.,.
With tYont-facing air intakes, that metal echoes radar
like a beacon. But the new bomber will have concealed
intakes, nunmtcd Hush beneath the flying wing. It also
may employ ,i version of a new intake-tunnel configura-
tion being developed fin? Rockwell's B-1 B.
('allcd the zigzag tunnel, this innovation eliminates the
straight-line air How that also Icts radar Hash directly into
the engine compressor. 'The new tunnel has twin channels
ccith a series of carefully designed curves that minimizes
radar reflections.
The expandable throat needed to reduce incoming air
speed and prevent a compressor stall in a high-dying su-
pertonic aircraft is gone. The result. is a radar footer, Sig-
n,ds entering the zigzag tunnel reflect back and forth at
the curves, instead of echoing a bright. reflection to a
radarscope.
'~We can do it because the B-l B is now a subsonic, low-
altitude penetrator," an Air Force officer said. ?There's no
problem with stalls.'.
I'he nc~i flying ~ti~uir; ~~~ill add another innovation. !t~
jet-engine exhaust will be cooled and masked, exit ing from
smoothly faired thrust. vents at the trailing edge. That
won't affect radar but will help protect the stealth Numb-
er from heat.-seeking missiles or detection by infrared
Sensor's.
Northrop's stealth aircraft also will benefit from radar-
ahsorhing coatings first developed for I,ockheed~~ legend-
ary SK-~ 1 Blackbird. 'that pl;i;.m got its name from the
ink}~-black coating that roduce~ its radar rignature and
camouflages it against thc~ dark sky.
Details on newer coatings are highly classified. But Nor-
thrup is said to he including that technology in its flying
wing.
B-1 B accessories
Avionics will make up the rest of the fighter's approach
to radar invisibility. While declining to discuss the elec-
tronics that will go into the flying wing, the Air Force pro-
vided some details on equipment for the low-observable
B-1 B.
First, the dish-type radar antenna in the nose of the
craft. is gone, replaced by a phased-array antenna that re-
sembles aflat, oval plate. "The dish became a radar target
itself in some: instances," an Air Force official said.
'The phased-array antenna never moves. It is angled
generally firrward, but its radiation is aimed electronical-
ly, and it doesn't reflect enemy signals. The system was
adapted off the. shelf from a radar employed in the F-]6
fighter.
The Air Force and Rockwell also eliminated an antenna
that ran down the B-I's back like a visible spine. That
spine provided angles just made to echo radar. 'The anten-
na, part of a programmable defensive-avionics system,
will he built directly into the aircraft.
'The. system is computer controlled and on-board pro-
grammable to seek and identify enemy radar or missiles.
'?Phese avionics are the current state of the art," the officer
said. `"They've been tested against surrogate Soviet sys-
tems and will defeat anything currently in their radar-
antenna inventory and any upcoming threats," he confi-
dently asserted.
'The system being developed Ior Northrop's stealth plane
is presumably even better.
"Kadar cross section is only one aspect that's going to
make asuper-penetrator," the officer said. "The other half
is the avionics. When you get the radar visibility down
very small, you can start manipulating the radar signals
so tho enemy doesn't see you."
'That means stealth-type aircraft will carry new elec-
tronic-countermeasure gear to identify ti radar station,
then transmit just the right signal to erase even the hum-
mingbird speck from its scope. The kind of countermea-
sure equipment now in use must be powerful enough to
obliterate the large radar signatures current aircraft
produce. Still, radar operators frequently know something
is happening, though maybe not what, when their scopes
are jammed.
"lf you can use just enough energy t.o foil each radar set,
they won't even know you're there," the officer ex-
plainod. .
If current funding levels continue, the B-1B will be op-
erational in 1986, with 100 of them flying by 19823. 'To pro-
tect against it, the Russians will have to spend five times
as much on defenses as the aircraft cost the U.S., according
to an Air Force source. And that's just the start. 'The Nor-
thrup stealth plane now is scheduled to be in the military
inventory by 1992. "That will take another five-fold ex-
penditure if they want to even think about stopping it,?
the officer said. m
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