The Lockheed SR-71 is a long-range, Mach 3+ strategic reconnaissance aircraft that was
operated by the United States Air Force.
It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the
1960s by Lockheed and its Skunk Worksdivision.
The SR-71 served with the U.S. Air Force from 1964 to 1998.
A total of 32 aircraft were built, 12 were lost in accidents but none of these was lost
to enemy action.
It has been given several nicknames, including "Blackbird" and "Habu".
Since 1976, it has held the world record for the fastest air-breathing manned aircraft,
Interestingly in 2013, Lockheed executive Robert Weiss generated lot of excitement when
he seemingly indicated to Aviation Week that defense manufacturer was developing a hypersonic
aircraft—and invoked the legendary SR-71 Blackbird spy plane by dubbing it the SR-72.
Since then lot of isolated new reports point to the fact Lockheed Martin might be up to
something.
In this video Defense Updates analyses the possible secret development of SR-72, the
successor of SR-71’Blackbird' Let's get into the details.
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The SR-71 was designed for flight at over Mach 3 and gather intelligence.
It had a flight crew of two in tandem cockpits The pilot was seated in the forward cockpit
and the reconnaissance systems officer in the rear cockpit.
The reconnaissance officer was responsible for operating the surveillance systems and
devices.
The SR-71 had 3 unique features that made it almost invulnerable:
1.
The SR-71 was designed to minimize its radar cross-section.
The design was an early attempt at achieving a ‘stealth' profile.
It was in painted dark blue, almost black, to increase the emission of internal heat
and to act as camouflage against the night sky.
The dark color led to the aircraft being nicknamed "Blackbird”.
In most situation, the radar stations were too late to detect it.
2.
The capability to fly at a sustained speed of Mach 3.2.
This enabled it to outrun SAM (Surface to Air) missile of that era.
The speed is also faster than the Soviet Union's fastest interceptor the Mikoyan-Gurevich MiG-25.
3.
SR-71 had the ability to reach extremely high altitude.
It had a Service Ceiling 85,000 ft (26,000 m).
Because of this service ceiling, SAMs were not able to follow it as they will be out
of thrust.MiG-25 was also not able to reach this kind of altitude.
The combination of these 3 factors made sure that no SR-71was ever shot down by an enemy
though it had flown inside the enemy territories repeatedly and penetrated deep inside.
The Blackbird was retired as spy satellites and stealthy long-endurance drones like the
RQ-170 came to the fore.
Spy satellites & long-endurance drones were more suited for discretely monitoring the
area of interest.
An object is said to be hypersonic once they exceed speeds of Mach 5 that is 5 times the
speed of sound.
This is about 1,715 meters per second or 3,836 mph or 6,174 km/h.
The SR-71 was powered by two Pratt & Whitney J58 axial-flow turbojet engines.
It was capable of producing a static thrust of 32,500 lbf (145 kN).
The innovative part was that at lower speeds, the turbojet provided most of the power while
at higher speeds, the engine largely ceased to provide thrust and the afterburner did
the work.
As per some reports coming out recently, Lockheed and the firm Aerojet Rocketdyne made a breakthrough
by developing a Combined Cycle engine.
The engine includes a turbine for speeds below Mach 3 and a scramjet for hypersonic cruising.
The scramjet is an innovation on the Ramjet.
Ramjet engine can power flight to supersonic speeds but scramjet can enable the craft to
reach hypersonic speeds.
These engines have no moving parts, like the compressors and turbines used in the turbofan
engines found on conventional jet planes.
They rely on the huge pressures created by fast airflow into the engine to ignite the
fuel and generate thrust.
Countries like Russia, China have been developing sophisticated layered air defense.
These systems are difficult for traditional aircraft & missiles to penetrate.
This is where hypersonic weapons come in.
Their extreme speed and ability to fly in unpredictable path give them a high probability
of penetrating the air defenses.
They will be very hard to track, let alone intercept.
It is to be noted that traditional ballistic missiles also reach hypersonic speed when
then descend down on the target but they follow a predictable predefined parabolic path which
could lead to possible interception by anti-ballistic missile defense systems.
Hypersonic weapons will be suitable for neutralizing well defended strategic military assets.
Russia has claimed that it has already fielded a Scramjet engine based hypersonic missile
named Kinzhal.
China is thought to be pursuing hypersonic weapons as well.
On June 12, 2019, India claimed to have test-fired a hypersonic weapon.
The U.S is taking steps to field its own air-launched hypersonic weapon.
Each of these are missiles and not aircraft.
A manned or unmanned aircraft capable fo hypersonic flight will be a ground breaking leap in military
technology.
It will open a new possibilities in aerial combat.
The hypersonic missiles which are under development cannot return to base and load up for further
sorties, there are basically for one time use.
But this is not the case for a hypersonic aircraft and it could be used as a bomber.
A single bomber could strike multiple target and then come to refill it weapons & fuel
for further missions.
Hypersonic missiles have not been mastered yet and there is still some time when they
will become mainstream.
Hypersonic concept bomber like SR-72 will be much harder to design.
Even if designed, there are other factors.
These will be very costly to operate and they may even have suspect stealth characteristics.
Stealth profile is achieved by 2 ways :
1.
Specially contoured external structure is designed.
Stealth aircraft like B2 is constructed so that there is no sharp edges or protruding
elements and has smooth curvature, the weapons are also carried internally.
This kind of design deflects the radar signals away from the emitting radar and it doesn’t
receive back the signals.
This way the radars are basically blinded.
2.
Even with the stealth profile, some radar signal can’t be diverted away from the source.
This is where Radar Absorbing Material (RAM) comes into play.
RAM covers the external parts of the aircraft so that radar signal is absorbed and don’t
reflect.
B 2 Spirit, F 22 Raptor & F 35 Lightning II all use RAM.
While the first aspect could be employed by SR-72 , use of the RAM may not be possible.
The heat generated by hypersonic travel will most likely burn away radar-absorbent materials
and expose the aircraft to radar.
Also, it is to be note that a hypersonic aircraft like SR-72 will require an entirely new crop
of weapons that can be at launch at such high speeds.
Lockheed officials have time and again teased military analysts and generally public with
statements that seem to imply that they are working on the successor of SR-71 and some
work is already done.
In 2018 at a science convention, Lockheed vice president Jack O’Banion stated “Without
the digital transformation [of three-dimension design technology], the aircraft you see there
could not have been made.
In fact, five years ago, it could not have been made.”
This seem to indicated that they have already developed something.
Later Executive Vice President Orlando Carvalho clarified and said to Flight Global “I can
tell you unequivocally that it [the SR-72] has not been built”, claiming O’Banions
quotes had been taken “out of context.”
It is unclear what to make out of these statements but deep down we all know that most impressive
military tech are the best kept secret and these tech don’t come in news.