First in a series celebrating Aviation Week’s 100th anniversary
Cloak and
Dagger
The development of stealth and counterstealth
Bill Sweetman Washington
S
CIA
tealth is not new. The modern era of stealth, which began in the mid-1970s
with Darpa’s Have Blue project, is half as old as radar itself, and precursor
projects date to the 1950s and earlier. That modern era saw stealth go from
a controversial, risky new technology to the center of a plan to rebuild U.S. combat
air forces with more than 2,000 new bombers, fighters and heavy attack aircraft by
the early 2000s. But today there are barely 200 operational manned stealth aircraft
in service and—even if all goes to plan—the fleet will not be majority-stealth until the
very late 2020s at best. The cost has been enormous, in money, the unprecedented
aging of the “legacy” force and in a loss of focus on conventional electronic warfare
(EW). In the meantime, counterstealth technologies have advanced, with major
investments underway in China and Russia.
Stealth Before Stealth
“The bomber will always get through,” British Prime Minister Stanley Baldwin warned
in 1932, but his dire prediction became outdated a few years later, as radar evolved from
a curiosity to the foundation of Britain’s air
defenses and a key to success in the Battle
of Britain. Radar was also critical to hunting
submarines. In June 1943, the German navy
launched a project named Schornfeinsteger
(“chimney sweep”), the first use of radar-absorbent material (RAM) to reduce a vehicle’s
detectability, treating 100-150 submarines.
The U.S. and U.K. both experimented with
RAM-treated aircraft in the 1950s. Under Project Rainbow in 1957, Lockheed modified a U-2
with devices to reduce its radar cross-section
(RCS), with little success; but the experience
led to a design for a stealthy flying-wing replacement, named Gusto. The CIA preferred
a high-speed design, but still pushed for RCS
Check 6 Bill Sweetman discusses the
development of stealth/counterstealth
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CROWN COPYRIGHT
Before radar, all aircraft were
stealthy if it was dark or they were
fying above the clouds. Radar was
invented independently in many
places, but Robert Watson-Watt
(1892-1973) was instrumental
in Britain’s development of radar
from a laboratory curiosity to an
integral part of an air defense
command-and-control system.
LOCKHEED MARTIN
reductions, and the Lockheed A-12 (photo,
left) flew in 1962 as the first aircraft with reduced-RCS shaping (canted vertical tails and
a chined body) and RAM built into the structure. In 1968 Teledyne Ryan flew the AQM-91
Compass ArrowUAV, designed to survive by
stealth alone.
Radar designers, however, stayed a step
ahead: Predicting radar scattering from a
complex shape, at diferent wavelengths and
aspect angles, was too complex to be done on
paper and testing and fixing the design with
models took too much time to be practical.
Lockheed Skunk Works founder
Clarence L. “Kelly” Johnson
(1910-90, on left, with chief test
pilot Tony LeVier) directed the frst
“radar camoufage” modifcations
to the U-2 and incorporated RAM
and RAS into the A-12 Blackbird,
but he was in fact highly skeptical of
the value of stealth alone when
not combined with speed and
altitude performance.
Pioneer Years
The modern stealth era started when increasing computing power, new sensors and
weapons came together with an urgent requirement that made a performance-compromised design acceptable. After radar-guided
surface-to-air missiles caused heavy losses in
Vietnam in 1972 and the Middle East in 1973,
Darpa called for a stealth demonstrator. Lockheed won the Have Blue contract in March
1976, using a computer program that could
LOCKHEED MARTIN
Johnson’s successor, Ben Rich
(1925-95), led the team that
won the Have Blue development
contract and made the F-117
into a workable airplane, with a
combination of borrowed systems
and completely innovative features. Rich said of the project’s
strict secrecy: “We’re like the
rabbi who hits a hole-in-one
on a Saturday.”
U.S. AIR FORCE
40 AVIATION WEEK & SPACE TECHNOLOGY/SEPTEMBER 14-27, 2015
AviationWeek.com/awst
LOCKHEED MARTIN
Alan Brown was part of the
“Brain Drain” of British engineers
who moved to the U.S. in the
1960s as the U.K. slashed
defense R&D. His contributions
to Have Blue and F-117 included
work on the fat-panel shape’s
aerodynamics and the “titanium
tennis racket” screens over the
infrared sensors.
the tightest security. Their very existence
was secret—although Aviation Week & Space
Technology reported on some aspects—and
they were tested at the Air Force’s secure
base at Groom Lake, Nevada, aka Area 51.
predict the RCS of a shape made up of flat
facets and covered with sheets of RAM.
The airplane (see photo, page 40, bottom)
flew in December 1977, and in 1978 the U.S. Air
Force ordered an operational development, a
subsonic bomber that could hit pre-surveyed
fixed targets in clear weather with a laserguided penetrator bomb; it was intended to
destroy Soviet air-defense command bunkers.
The F-117A flew in June 1981 and was declared
operational, with many limitations, in October
1983. Eventually, 59 were built and the jet was
used with great success in the 1991 Gulf war.
Northrop was chosen in 1976 to build an
experimental reconnaissance airplane, codenamed Tacit Blue, using curved profiles and
in 1978 competed with Lockheed for a stealthy
strategic bomber. Lockheed also experimented
with a stealth cruise missile, Senior Prom.
All these programs were conducted under
High Hopes
Less than five years after Have Blue’s first
flight, stealth was considered key to leveling
the airpower balance with the Soviet Union.
Northrop, with a reputation built on lightweight fighters, was the surprise winner to
build the Advanced Technology Bomber (later
named B-2) in October 1981 (see photo, page
43, top). In May 1983, the Air Force revised
its requirements for the Advanced Tactical
Fighter (ATF) project—which led to the Lockheed Martin F-22—to emphasize stealth, and
tightened them again in 1985 before awarding competitive development contracts, in
Shaping–canted sides
and aligned edges
Propulsion and weapon integration
LOCKHEED MARTIN
Denys Overholser was recovering
from a skiing accident when
Ben Rich asked him to look at the
RCS problem. He led the development of a computer program that
would accurately model the radar
return from a full-size aircraft. Diffculty: There could not be a single
curve in the shape. “They decided
that I wasn’t the village idiot so
I became a genius instead,” said
Overholser later.
In Your Own Words
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U.S. AIR FORCE
USAF/ AIRMAN 1ST CLASS CARLIN LESLIE
Other stealth projects included Quartz, a
large UAV designed to loiter for 24 hr. over the
Soviet Union; the General Dynamics AGM-129
Advanced Cruise Missile; and the Army’s LHX
scout helicopter, later the RAH-66 Comanche.
Stealth work was global. MBB in Germany
wind-tunnel tested a supersonic fighter design, Lampyridae, in 1985; when the U.S. discovered it in 1987, the Air Force was shocked
by its resemblance to the F-117 and dispatched
experts to examine the Germans’ claim that
it was coincidental. (It was.) France regarded
reduced RCS as essential to the Rafale project and built the vast Solange indoor range at
Bruz in Brittany to aid development.
October 1986, to teams led by Lockheed and
Northrop.
The U.S. Navy, not to be outdone, started
development of a heavy, long-range carrierbased stealth bomber, the Advanced Tactical Aircraft, in 1984: A General Dynamics/
McDonnell Douglas team was tapped to build
the A-12 in 1988 after Northrop and Grumman’s team refused to ofer a fixed-price bid.
By that time, the Navy and Air Force had
agreed that a version of ATF would replace
the Grumman F-14 and that the A-12 would
succeed the F-111, so that well over 1,000 of
both types would be needed.
Three of Northrop’s original
stealth team—known as the
“Whalers” because the V-tailed,
bulbous-nosed Tacit Blue prototype
was nicknamed “Shamu”—visit
the U.S. Air Force’s B-2 squadron
in 2009. Stealth specialist John
Cashen is on the left, next to
Irv Waaland, chief engineer on
Tacit Blue and B-2. (“You know
just enough to be dangerous,”
was Cashen’s summary of Waaland’s
knowledge of electromagnetics.)
B-2 program manager Jim Kinnu
is third from the right. Also in the
photo: to the right of Waaland are
Air Combat Command chief scientist
Janet Fender and Brig. Gen. Garrett
Harencak, 509th Bomb Wing commander (now a two-star in charge
of USAF nuclear weapon programs).
Second from right is government
B-2 engineer John Griffn, next to
Northrop Grumman’s Dave Mazur.
Boom and Bust
The end of the Cold War coincided with
recognition that the difculty of developing,
building and operating highly stealthy com-
Visual and infrared signatures
Gallery Take a look at the group
of aligned disciplines that are brought
together to produce stealthy vehicles:
AviationWeek.com/StealthTech
Flir Measurement
1963 contrail-suppression tests
Radar-absorbent
structures
and materials
IOWA STATE UNIVERSITY
Typical radar-absorbent edge structure
Top Coat
Tape
Adhesive
Promoter
Primer
Structure
Stealth pioneers tend to keep a
low profle, but none has done
better than Alan Wiechman, who
was instrumental in stealth programs at McDonnell Douglas and
then Boeing for almost 30 years,
but scores exactly two mentions
on the latter’s website. Hired from
the Lockheed Skunk Works after
McDonnell Douglas’s defeat
in the ATF contest, Wiechman
was a
founder of
St. Louis’s
Phantom
Works and
directed
stealth
work in two
directions:
reducing
the RCS of conventional aircraft,
and extreme-low-observable,
tailless shapes. Wiechman retired
in 2014 and formed a consulting
company, Eagle Aerie, together
with the founder of the
Air Force’s Rapid Capabilities
Offce.
Structure
Caulk
Fairing
Gap Treatment
AviationWeek.com/awst
AVIATION WEEK & SPACE TECHNOLOGY/SEPTEMBER 14-27, 2015 43
U.S. DefenSe Department
Bird of Prey demonstrators in 1996, won
a Darpa contract in 1999 to fy the frst
UCAV demonstrator, the X-45.
Stealth Goes Global
Lockheed Martin won the bid to
develop the F-35 JSF in October 2001,
but in barely two years, runaway weight
gain forced a major redesign. The delays were underestimated and costs
ballooned. In April 2002, meanwhile,
Sukhoi was selected to lead development of the PAK-FA stealth fighter;
work on China’s Chengdu J-20 started
around the same time.
Although stealth and aerodynamic
advances were promising remarkable
results in both efficiency and signatures, it proved hard to defne a UCAV
program that could consistently draw
funding away from manned airplane
programs. The Joint Unmanned Combat Air Systems program was launched
at Darpa in 2004 with the goal of getting
an operational system in 2010, but was
canceled two years later, leaving the
Navy to carry on with the Northrop
Bill Sweetman/aw&St
Grumman X-47B carrier-landing project. The X-47B (see photo, above) accomplished carrier takeofs and landings in 2013, but a running dispute over
requirements has stalled development
of an operational Navy UCAV.
Air Force funding went into the defnition of a stealthy Next-Generation
Bomber (NGB) and—most likely—into
a high-altitude, long-endurance, very
stealthy UAV, the Northrop Grumman
RQ-180. But in 2009 the NGB was canceled as too expensive and risky. In Europe, BAE Systems and a Dassault-led
multinational team each had started
development of UCAV demonstrators—
Taranis and Neuron—in 2006. Japan’s
Mitsubishi soon began RCS tests of its
ATD-X stealth fghter prototype.
Meanwhile, in February 2004, the
U.S. Army cited the dubious value of
a radar-stealthy armed helicopter and
scrapped the RAH-66 Comanche program—although some of its technology may have made its way into the
secret H-60 Black Hawk variant that
was used to raid Osama bin Laden’s
compound in Pakistan in May 2011.
The Future Starts Here
2010 may have been a watershed year
in stealth technology. Russia’s Sukhoi
T-50 had its frst fight in January; BAE
Systems’ Taranis was unveiled in July;
and China’s Chengdu J-20 made its surprise debut on the Internet in December.
In February, then-U.S. Defense Secretary Bob Gates fred the JSF program
manager and launched a major revision
of the program. This closely followed the
controversial decision to cap production
44 AviAtion Week & SpAce technology/September 14-27, 2015
Gallery See some of the stealth
technology stories broken by
Aviation Week AviationWeek.com/AWStealth
of the F-22 —which had entered service
in 2006 but had proved expensive to operate and upgrade—at 187 aircraft.
During 2010, too, the Air Force developed a revised plan for a Long-Range
Strike Family of Systems, including
a less ambitious Long-Range Strike
Bomber (LRSB) program with an initial operational capability date in 2025.
This won Gates’s approval in early 2011.
However, alternative approaches
and counterstealth technologies also
emerged. At the Farnborough Airshow
in July, Boeing unveiled a study for an
Advanced Super Hornet with stealth
enhancements and a centerline weapon
pod. Selex-ES began claiming more
openly that its IR search-and-track systems could detect stealth aircraft well
beyond visual range. In 2011, Russia’s
Nizhny-Novgorod Research Institute of
Radio Engineering (NNIIRT) started
production of the 55Zh6M mobile air
defense radar complex, centered on
a massive VHF active, electronically
scanned array (AESA) radar designed
to detect stealth targets (see photo, below). Now, in late 2015, China and Russia
are persisting with the J-20 and T-50;
Britain and France are jointly defning
Bill Sweetman/aw&St
bat aircraft had been grossly underestimated. Overweight and far behind
schedule, the Navy’s A-12 was canceled
outright in January 1991, followed in
December 1992 by the overambitious
Quartz. Technical difficulties, delays
and overruns conspired with geopolitical change to cut B-2 production to 21
aircraft from 133. The Navy ATF was
never funded. Lockheed was selected
to build the F-22 in 1991, but production was cut to 442 aircraft from 648
two years later and the program slowed
down; it entered service after 2000.
The Clinton administration, taking
ofce in January 1993, scrapped emerging plans to develop an Air Force/Navy
substitute for the A-12, variously called
A-X and A/F-X, and an Air Force F-16
replacement. Instead, the Pentagon developed a plan for a smaller, multirole
aircraft that would replace F-16s, F-18s
and F-15s for both the U.S. and its allies,
and that would be built in conventional,
carrier-based and short-takeof, verticallanding versions. The goal was an aircraft that would be stealthy but cost little
more than an F-16 to buy or operate—the
emphasis was not on a stealthier aircraft
than an F-22, but on one that would cost
less to buy and maintain. In November
1996, Lockheed Martin and Boeing won
competing development contracts for
the Joint Strike Fighter (JSF) project,
fying their X-35 and X-32 demonstrators
(see photo, below) in 2000.
A new class of stealth aircraft
emerged in 1996, with the frst discussions of unmanned combat air vehicles.
Boeing’s Phantom Works, which had
fown the unmanned X-36 and manned
an operational follow-on to Taranis and
Neuron; South Korea and Turkey are
seeking international partners to help
develop stealthy fghters. Tupolev received a Russian defense ministry contract to develop the PAK-DA stealth
bomber in 2014, but upgrading the supersonic Tu-160 may take precedence.
And the development of counterstealth sensors continues. China has unveiled its equivalent of NNIIRT’s VHF
AESA radars, the JH-27A Skywatch-V,
as well as the Chengdu Divine Eagle—
a UAV designed as the platform for a
large-aperture sensor. Saab claims its
JAS 39E Gripen, with IRST and an allnew EW suite, will be as survivable as
an F-35 even against high-end threats. c
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