It was the height of the Cold War, and the United States and Soviet Union were at each others’
throats. Their powerful nuclear arsenals kept the tension from turning into a hot war - if one fired
on the other, the response would likely wipe out all life on Earth. So the two geopolitical rivals
were left to fight proxy wars in other countries, as the United States fought to keep communism
from expanding and the Soviets tried to reduce American influence in the post-World War II era.
The most powerful currency in the Cold War era was
information on what the rival superpower was doing - but how to get it safely?
Espionage was common as both countries sent agents into enemy territory
to gather information on the military and weapons program of their rival.
The success of these missions depended on the ability of the spy to get access to sensitive
information, and spies faced constant danger. A captured spy faced lifelong imprisonment or
execution - unless they could be traded in a prisoner exchange between the bitter enemies.
There had to be a better way of getting information - and that
led to the rise of the reconnaissance aircraft.
The most important information the United States wanted to get from the Soviet Union
was updates on their nuclear missile program, and access was strictly limited.
So the best way to keep abreast of major developments was from the air.
Spying from planes had a long history, going back to the French using hot air
balloons to spy on their enemies at the end of the 18th century. As photography was developed,
agents could take photographs from balloons and later from early planes. But by the time of the
Cold War, anti-aircraft guns were common. Spy planes could be shot down, and the pilots would
either be killed or captured - as happened to Air Force pilot Francis Gary Powers in 1960.
That led to one of the tensest prisoner exchange negotiations in the Cold War. Powers eventually
returned home safely, but the United States knew they couldn’t afford more incidents like this.
One of the most powerful and successful corporations in
American history was about to enter the field,
and their newest spy plane would help the United States turn the tide of the Cold War.
The Lockheed Corporation was founded in 1926, and was one of the biggest names in Aerospace
production during the 20th century. While they nearly shut down during the Great Depression,
they were saved from economic ruin during World War II. Suddenly, there was a need for mass
airplane production again. Their Hudson bomber was invaluable in taking out German submarines,
and their P-38 Lightning fighter aircraft was commissioned exclusively by the US Air
Force during the war. After the war was won, they turned back to
civilian aircraft and launched the L-049 constellation for Trans-World Airlines,
which cut the time to fly from New York to London to only thirteen hours.
But it was their most secretive division that would be the most
significant as the Cold War heated up.
They were called Skunk Works, but they didn’t stink at their jobs. The Advanced Development
Programs division of Lockheed Corporation was where they developed their top-secret projects,
usually for military or government use, and the designers promoted to
the division were given a higher degree of freedom than your average Lockheed talent.
They had been developing military projects for decades, but now the United States had
a new mission for them. They needed a spy aircraft that would be able to move faster,
go higher, and evade the detection of Soviet anti-aircraft technology.
This was the genesis of the Lockheed SR-71 Blackbird.
It was the early 1960s when the SR-71 was put into production
as a joint program of the United States Air Force and NASA. The basis was the Lockheed A-12,
which had been approved in 1959, but the Cold War was advancing fast. The
main innovation of the A-12 was its smaller radar cross-section, which made it harder
for anti-aircraft radars to pinpoint it - essential for reconnaissance aircraft.
So how to reduce an aircraft’s radar cross-section? There are several key factors.
First, the size of the target. Smaller is better. Even more important is the material the target is
made of - metal is highly detectable to radar, while plastic and fiberglass are much harder
for even advanced radar technology to detect. Also important are the size of the target relative to
the wavelength of the radar, the incident angle, the reflected angle, and the polarization of the
transmission and radiation. The A-12 was one of the most radar resistant aircrafts of the time.
Its designer, however, believed he could do even better.
Clarence “Kelly” Johnson was one of the best designers American aerospace had ever seen,
and he was brought in to guide the development of the SR-71.
Military experts wanted him to design a plane that could double as a bomber,
but it was ultimately decided that the SR-71 would solely be a reconnaissance aircraft
to best focus on its strengths. The main structure of the A-12 was kept, but with
one major change - it would be painted with “iron ball paint”, which contained tiny metallic
balls. This not only didn’t make the aircraft easily detectable like standard metal would,
it absorbed the radar energy that hit the plane and converted it to heat instead of reflecting it.
The SR-71 was designed to be one of the fastest aircrafts ever produced by the United States,
flying at Mach 3 with dual cockpits. This allowed the plane to carry both a skilled
pilot, and a reconnaissance expert who would operate the spy technology in the aircraft.
Most previous reconnaissance planes only contained a single pilot to minimize weight,
but this required the pilot to pull double duty - not an easy task when flying at top speed through
hostile air. Able to fly higher and faster than any other reconnaissance plane of the era,
its low radar cross-section gave the enemy very little time to fire a surface-to-air missile.
By the time the radar was able to lock on, the plane would be long gone.
The next critical question - How to manufacture the SR-71?
Titanium was the preferred choice of metal for aircraft construction because of its lightweight
nature and incredible strength, but its use was normally limited due to a combination of its cost
and the challenge of acquiring it, but the US military knew they couldn’t cut any corners on
a game-changing aircraft. The final design for the SR-71 Blackbird was composed of 85%
titanium with the rest being highly resistant polymer composites. They were able to design a
titanium alloy that combined the metal with chemical elements, creating a lower melting
point. It was an extended game of trial and error to find the right combination - at
one point they discovered they needed to use distilled water rather than tap water
in the processing because the small amount of chlorine in tap threw the entire process off.
There was only one problem - the best source of Titanium in the world was the Soviet Union.
The Skunk Works team was forced to conduct an elaborate operation to find the needed rutile
ore that was essential for the production of titanium. They couldn’t buy it directly because
trade between the United States and Soviet Union was virtually nonexistent, so they worked through
third-world countries and proxies that would purchase the ore and ship it back to the United
States covertly. Eventually they collected the ore they needed, and production could begin in full.
The final design by “Kelly” Johnson incorporated all the strengths of its predecessors,
but the SR-71 Blackbird had unique properties that took it to the top of the aerial reconnaissance
game. It had Cesium-based fuel additives that made the exhaust plumes slightly harder to see,
and sharp edges along the side called chines that reduced radar reflection and created
extra lift and aerodynamic performance. Air inlets reduced wind resistance,
allowing the aircraft to hit an unprecedented Mach 3.2, with the design working to turn the
air subsonic when it entered the engine to prevent interference.
The real core to the SR-71’s success, though, was in its powerhouse engines.
Powered by two Pratt & Whitney J58 axial-flow turbojet engines, this plane had the most
powerful flight engines available. It reached peak efficiency at a cruising speed of Mach 3.2,
and the afterburner provided over a quarter of the thrust for maximum
efficiency at take-off. Able to regulate its temperature effectively without losing power,
the plane was less likely to experience malfunctions in mid-air. Its pneumatic
start system was quieter than most start carts and was installed at major operating bases.
The next question - What was the most effective fuel for the SR-71 to use?
The Skunk Works team tested several unconventional fuels including coal slurry
and liquid hydrogen formulas, but they ultimately settled on JP-7 turbine fuel,
which was popular at the time due to its low volatility and versatility for powerful aircrafts.
It was challenging to light, requiring an injection of air-flammable triethylborane,
and the plane would take off with a partially-full tank to ensure it could
still fly if one of the engines failed. This was a good way to keep the plane light - but it also
meant the flights had to refuel in-flight by connecting with a tanker aircraft.
The SR-71 was a well-oiled machine, but that wasn’t the only key to its success.
It was one of the first planes of the computer age - with the technology to match.
The SR-71 was one of the first aerial reconnaissance planes outfitted with
an astro-inertial guidance system, which used celestial tracking and observations to correct
errors in the navigation system. The quartz window on the plane was designed to provide optimal
visuals, and this allowed the guidance system to be among the most accurate in the world. The
reconnaissance section of the plane was the most advanced for its time, containing state-of-the-art
tracking and infrared cameras and defensive systems for alerting the pilots of incoming
missiles and fighters. Its camera systems were located in the chines of the fuselage or nose, and
it was capable of delivering on-ground visuals far more accurately than any other plane to that date.
But even the most advanced plane isn’t immune
to mishaps - and the makers of the SR-71 were prepared.
The SR-71 Blackbird flew so high and so fast that standard flight suits didn’t provide enough
oxygen. The team designed special pressurized suits with the help of the David Clark Company
that looked much like space suits, and the plane was outfitted with pressure control and
a heavy-duty cooling system to keep the pilots safe at cruising altitudes. As the planes were
designed for long-distance reconnaissance flights, they were equipped with specially
designed water bottles and food supply that would keep any leakage or stray crumbs from interfering
with the machine - very similar to how astronauts ate and drank on space flights in zero gravity.
It was 1964. The design was complete. It was time for the SR-71 Blackbird to take flight.
The first test flight took place on December 22nd, 1964, with Bob Gilliland at the helm.
The flight hit a top speed of Mach 3.4, which was topped by Major Brian Shul in a mission
over Libya where he successfully evaded a missile. As 1966 rolled around, the SR-71
was ready to enter service. The Vietnam War was ramping up and US involvement was escalating,
so having eyes in the air was invaluable. The aircrafts were stationed in Okinawa’s Air Force
base, established after World War Two, and flew missions over North Vietnam and Laos,
averaging one flight a week their first two years. Turnaround required a lot of
maintenance due to the complex planes’ design, but experience and production of more planes cut
that down. By 1970 they were flying two flights a week, and by 1972 flights were almost daily.
The flight record of the SR-71 exceeded the Air Force’s hopes. They flew over 3,500
missions. Only two flights were ever lost due to mechanical failures, and only one crew member
was ever lost - navigation systems specialist Jim Swayer was killed in a flight accident. However,
out of over 800 surface-air missiles fired at the SR-71 from North Vietnam,
not a single one ever hit its target and no SR-71 was ever shot down by the enemy.
But the SR-71 was about to go up against an even deadlier enemy - politics.
The program was a massive success and the SR-71 proved itself,
but it was expensive. As the Vietnam War ended and appetite for military spending decreased,
it became harder to get money allocated by Congress. Upgrades to the Lockheed U-2 added
a data connection, which the SR-71 lacked, and many in Congress wanted to focus on strategic
bombers rather than reconnaissance aircraft. By 1989, the money had run out, and the SR-71’s
primary military operations were brought to a close, although a few missions were run into
1990 with the planes still functioning. And the US’ Cold War secret weapon went into storage.
But that wasn’t the end of the story for one of the best spy planes ever designed.
It was the 1990s and the Cold War was over, but multiple little hot wars were creeping up
all over the world. North Korea was ramping up its weapons production,
several conflicts were escalating in the Middle East, and the United States would soon wind up
enmeshed in an international intervention in the former Yugoslavia. They needed spy planes again,
and they had no time to design a new plane with the capabilities of the SR-71.
Congress ultimately approved 72.5 million dollars to restore the SR-71s to service
in 1994, and the Skunk Works team at the now-renamed Lockheed Martin went to work.
They were equipped with a data link, and ran until 1998, when the SR-71 was formally retired.
The planes were handed off to NASA, where they were used for civilian aerospace work
for another year. The SR-71 Blackbird no longer flies, having been replaced by successors and
unmanned drones that do most of the heavy lifting in spywork for the military today.
But they can be seen on display in museums and at flight research centers,
where they remain the foundation for the next generation in high-speed manned
aircraft - the Lockheed Martin SR-72, also known as the Son of Blackbird. It’s still
in development - but watch the skies. A test vehicle could take flight by 2023.
Now for more on the airplanes of war,
go watch “Why is the F-35 so expensive?” or check out this video instead.