Shourya/Sagarika Missile
Introduction
Shourya1 and Sagarika is a new common missile that
can be launched from multiple platforms viz. ground,
submarine and mobile launcher. Naval version is
called Sagarika while the land based version is called
Shourya. Indian doctrine of Minimum Credible Nuclear
Deterrence envisages "No First Use" (NFU) policy and
a triad of nuclear counterstrike capability. The land
based Agni-2 missile range is limited to about 3,300
Km, and the longer range Agni-3 will enter service
soon. The sea leg of the triad based on blue water
naval assets dispersed across the world's oceans is
most survivable thus a critical part of the triad. The
ability to reach all corners of a potential challenger
requires a range of 5,000 to 8,000 km. DRDO is
developing sub surface launched long range Agni-3SL
with heavy MIRV payload and ABM countermeasures.
Indian nuclear powered ATV due for sea trial in 2009
will reportedly carry 12 launch tubes2 of 2.4m diameter.
Launch tubes can be flexibly configured to either carry
a 2 meter diameter Agni-3SL or three wooden rounds3
of 0.74m diameter K15-Sagarika missile. Shourya and
Sagarika fills the short to medium range gap that is
below Agni-III’s minimum range. At operational level
these missiles provide for range of warheads
necessary for graduated nuclear escalation as
enunciated by Indian staff and military warfare
collages.
Shourya and it's relative size
This multifunction missile made in large quantities
would fulfill India's immediate requirements. The
missile optimally matches latest types of strategic
weapons tested at Pokhran-II in 1998. The missile will
most likely take over the strategic weapons role of
Prithvi and Agni-1 missiles, and make them
unambiguously dedicated for conventional roles thus
stabilizing nuclear deterrence. Shourya and its
counterpart Sagarika has been tested 6 times 5 till
date. The missile is expected to enter service in 2010.
Sagarika will be deployed on submarines and very
likely on ‘Sukanya’ class naval vessels too.
Wooden round. Dense smoke from launch gas
generator reduces Shourya’s launch signature [Photo
courtesy: DRDO via Shiv Aroor]
Description
Shourya is a compact, slender, two-stage, solid fuel
missile designed as a wooden round. The missile
development was initiated as project K15 and was first
flight tested6 on 27 October 2004 in the guise of solid
fueled Prithvi-III7. It is stored, deployed and launched
in a fiberglass composite canister, which is easy to
handle, mobile and can be flexibly deployed on
different types of surface and sub-surface platforms.
Shourya and Sagarika share a common design. The
missile is sealed and can be launched from a moving
submarine at 50 meter depth. The 6.2 tonne Shourya
is 10 meters long, and has two solid fuel stages of
0.74 meters diameter. The first stage booster is about
two meters long and the second about six meters long.
The missile supports a range of unitary warhead
configurations, weighing 180 to 1,000 kg. High missile
accuracy and ability to fly in a highly depressed
trajectory well within atmosphere indicates it is a
weapon of choice to interdict Command & Control
(C&C) and preemptive tactics.
The sixth test flight on November 12th, 2008 was a
depressed trajectory flight (at Mach 6 and 50km
altitude) with continuous rolling to dissipate heat over
a larger surface demonstrated mastery of difficult
aspects of rocketry involving sustained hypersonic
flight.
The wooden round design sealed in a fiber glass
canister with the aero fins folded inside in a clean &
controlled environment makes it maintenance free and
tamper proof. The missile is launched by a hot gas
generator developing 15-200 bar pressure using high
burn rate HTBP based composite propellant. The thick
dark gas cloud greatly reduces the thermal signature
of the missile.
Figure 3: Shourya on Mobile launcher. [Photo: DRDO]
Once out of the launch tube the first stage booster
motor ignites taking the missile to 5Km altitude when
the main second stage motor takes over. The booster
debris reaches a maximum altitude of 6 km, well
below the horizon of radars beyond 330 km. The clean
and small diameter missile presents a tiny RCS (radar
cross-section). The second stage air fins provide
necessary in-flight trajectory control. The main motor
is typically expended at 33 km altitude well within the
atmosphere; however the air fins remain effective
beyond post boost phase. The air fins also allow the
missile to fly in a depressed trajectory as well as
cruise and glide in sustained hypersonic regime at 50
km altitude. The payload separation can be done
much later after exploiting aerodynamics for trajectory
modification during ascent or descent. The missile is
resistant to ABM defense8.
Figure 4: Inside view of the ATV missile launch tube
that hosts 3 Sagarika missile canisters. [Photo: DRDO]
Re-entry Vehicle
Shourya Re-entry Vehicle (RV) supports wide range of
weapons, with total payload mass ranging from 180 to
1,000 Kg. The missile range is a function of payload
mass (see graph in Figure 7 below).
The November 2008 test unveiled the new generation
RV that is designed and optimized for newer boosted
fission and thermonuclear weapon (including those
awaiting confirmatory test). The sharp nose high ‘eta’
(Ballistic coefficient 9 ) RV design employs 16 cm
diameter blunt nose and half angle of 12° that is
mounted on a payload adapter to interface with the
0.74m diameter mission control module atop the
upper stage. The high ‘eta’ RV in combination with
an all carbon composite body enables higher re-entry
speed even with a light weight payload10.
The all carbon composite re-entry heat shield with
multi-directional ablative carbon-carbon re-entry nose
tip make it very light and tough16. This very light RV
mass enables scalable payload and range tradeoff
especially for lightweight warhead.
Propulsion
The Shourya has two solid fueled stages of 0.74m
diameter. This diameter is compatible with a recently
tested Indian sub-surface launch system that has a
2.4 meter diameter launch tube17.
First Stage: The first stage solid fuel booster is
approximately 2 meter long and weighs about 1,300
kg including 1,000 Kg high density fuel. The booster
lifts the missile to an altitude of 5 km so that the
second stage can operate more efficiently at low
atmospheric pressure. It uses hot gas reaction control
for initial control of yaw, pitch and roll before the air
fins unfold and missile gains sufficient velocity for
aerodynamic control surfaces.
Figure 6: Second stage motor [Photo: DRDO]
Second Stage: This 6 meter long stage weighs
about 3.6 tonne and generates 16 tonne thrust. Casebonded
HTPB-based composite propellant with low
burn rate is ignited by a small pyrogen ignition motor.
The case is made of 250 grade maraging steel to
maximize fuel mass fraction that is critical for scalable
payload versus range flexibility. Its nozzle is made of
composite material with metallic backup and carbon
phenolic liners. The interstage coupling uses a softstage
separation mechanism and retro rockets for
reliable and safe stage separation.
Navigation & Accuracy
Shourya largely carries the proven avionics set of
Agni-III however for more extensive aerodynamic maneuvering, it is augmented by new sensors and
flight control system. Shourya will also benefit form
Indian Regional Navigation Satellite System (IRNSS)23
expected to be ready by 2012, to ensure guaranteed
national access to precision navigation. These
systems enable high accuracy required for precision
strike.
Range versus Payload
Missile range & payload mass are inversely related. It
is interesting to note that press reports Shourya’s
range for 1,000 kg and 500 kg payload. The former
corresponding to 1980 vintage 200Kt FBF warhead
and the latter corresponding to 150Kt FBF that is yet
to be field validated. The official reporting obfuscates
missile’s much higher range corresponding to field
tested 17Kt FBF warhead that is mainstay of Indian
deterrence.
Figure 7:
Figure 7: Range versus RV payloa
Conclusion
Shourya class of missile is truly a multi-services
missile that has desirable attributes of small size,
mobility, stealth, rich set of warhead options,
robustness and cost that could make it the most mass
produced Indian missile. It complements the long
range Agni class missiles to provide Indian military
commanders global range necessary to secure Indian
interests.
http://www.indiaresearch.org/Shourya_Missile.pdf
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