with a cruising speed of mach 3.2 and an
estimated top speed of mach 3.5 the
sr-71 blackbird holds seven aircraft
records including the fastest
air-breathing manned aircraft officially
measured at 2190 3.2 miles per hour
though its top speed is still classified
in a climb the aircraft has been known
to reach an altitude of 95,000 feet
twice as high as the highest altitude
permitted for a commercial passenger jet
the mikoyan-gurevich mig-21 and aircraft
in the world it's made to go mach 2.8
but that uses so much fuel that it can
only go that fast for a few minutes in
extreme circumstances the plane has been
pushed to mach 3.2 but at a cost of
major damage to the plane's engines on
the other hand at mach 3.2 the sr-71
blackbird is just getting warmed up so
how did Lockheed skunkworks get a plane
that weighs up to 78 tons to fly around
the world non-stop at three times the
speed of sound 16 miles out considering
it was designed in 1962 in a time before
computer-aided design the answer is very
carefully the Blackbird program
originally called oxcart pioneered many
of the technologies found only in the
most advanced military aircraft today
including an all titanium airframe a
mostly titanium skin the use of
lightweight composite materials for the
rest of the skin and some key components
chines that run down the length of the
aircraft should reduce drag and increase
lift a stealthy design that minimizes
its radar cross-section and in a time
before GPS the ability to circumnavigate
the globe with pinpoint accuracy but the
real key to the Blackbird success came
down to two things an extremely
aerodynamic design and a very unique
engine
when you look at the Blackbird you can
see the sleekness in its aerodynamic
design looking at its vertical
cross-section you can see how balanced
it is above and below a central
horizontal plane its delta wing is
relatively thin minimizing its
disturbance through the air when you
look at it from above you can see how
its whole body fits within a single
elongated triangle running from the
front pitot tube to the wingtips this
makes sure that the front shock wave
created by the nose at supersonic speeds
doesn't intersect with the rest of the
aircraft reducing overall drag its main
body is straight and long like an arrow
with a small amount of taper as it
reaches the back to gracefully shed the
air flowing above and below the aircraft
but all of the aerodynamics in the world
won't push a plane up to Mach 3 for that
you need the Blackbirds very unique
engine the pratt & whitney j58 turbo
ramjet at slow speeds the j58 works just
like other jet engines with an
afterburner air flows into the front of
the engine through a bladed compressor
fan which squishes the air and pushes it
into tubes called burners here fuel is
added and burned the hot exhaust flows
out of the burners through the rear
turbine making it spin which drives the
compressor to keep the cycle going the
force of the exhaust leaving the engine
pushes the airplane forward
but jet engines are limited in the
amount of force that can generate
through exhaust alone the fuel supply
has to be limited in the burner to
reduce the heat of the exhaust so that
the turbine doesn't melt this means that
the exhaust still contains a lot of
oxygen so in order not to waste it
additional fuel is added into the stream
of exhaust and burnt after it passes the
turbine but before it exits the aircraft
or additional thrust this is what we
call the afterburner
up until mach 2.2 this is the same cycle
that the Blackbird uses for thrust
however above Mach 2.2 the j58 pulls out
a big trick six large tubes open that
direct 20% of the dense air from the
compressor around the burner and turbine
moving it directly into the afterburner
this helps get around the biggest
problem with all afterburners they are
incredibly inefficient
they can provide a lot of force but at a
huge fuel cost on the other hand the
cool dense slow-moving air coming
directly from the compressor extracts
more power out of the fuel added in the
afterburner when these bypass tubes open
the standard turbojet is converted into
what's called a turbo ramjet a ramjet
uses the forward motion of the aircraft
to compress the air before combustion
and the fuel is burnt directly before
exiting the engine kind of like a rocket
but Ram Jets can't be started on the
ground the plane has to be moving before
the ramjet can start working so for
takeoff and landing the turbojet part of
the j58 does all of the work while at
the cruising speed of mach 3.2 it only
provides about 20 percent of the plane's
forward thrust with the ramjet
afterburner providing the rest ah
synergy the interesting thing is that
above Mach 2 Ram Jets are more
fuel-efficient than turbo jets which
means that the Blackbird gets better gas
mileage at Mach 3 point 2 then it does
traveling at slower speeds wha these
unique design elements are what allowed
the plane to cruise higher and faster
than any other manned aircraft its
convertible engines give it the best of
both worlds a turbojet to take off land
refuel and bring it up to speed and a
ramjet to give it the power to fly 3200
nautical miles at three times the speed
of sound on one tank of gas and
considering that all that was designed
with just a pencil paper and a slide
rule it makes the Blackbird even that
much more of a technological achievement
unfortunately the Blackbird will never
fly again
although it outran every one of the
4,000 missiles fired at it during its
missions the cost to fly and maintain
the aircraft was so great that in 1990
with the increased availability of
surveillance and strike drones the US
Congress ordered the birds retirement
three planes were reactivated in 1993
due to increased tensions in North Korea
and the Middle East but these planes
were again retired in 1998
NASA continued to operate to sr-71s as
scientific test platforms until they to
retired the plane in 1999 you may have
heard at the end of 2013
Lockheed Martin proposed a successor to
the sr-71 called the SR 72 even if it is
ever produced it will still never break
the sr-71 s records though it's designed
to fly at speeds from zero to Mach 6
like many other recent advances in
aviation the SR 72 is a drone it's
turbojet engine for takeoff and landing
is housed separately then it's
supersonic scramjet leaving the J 58 and
the Blackbird family to be forever
unique a fantastic and surreal memory in
the history of aviation the plane that
dreams are made of for tech laboratories
I'm tech Adams saying keep thinking and
thanks for watching
the well known sr-71 is actually the
fourth airplane in the Blackbird family
the original plane designed by Lockheed
skunk works was the a12 spikeless it's
not our average museum it's not just to
stop on your way by as you're passing
through this is a destination