Agni I

Section: Ballistic Missiles; Updated on: October 12, 2009;  

The Agni-I (Fire) is a 15-metre tall, 12-ton, single-stage, solid-fuelled, medium range ballistic missile. The missile is smaller than its big brother - the Agni-II IRBM - in dimensions and range, but can still carry a one ton nuclear payload to most targets in Pakistan without having to be deployed at the borders. The core and triggers can be swiftly assembled by BARC (Bhaba Atomic Research Centre) and DRDO (Defense Research & Development Organisation) - within India’s avowed no-first-use paradigm. Agni-I is also designed to be launched from a rail-based mobile launcher; one that can move on a standard broad-gauge rail system and also from a road-mobile launcher system. DRDO’s Ahmednagar-based VRDE (Vehicle Research & Development Establishment) and the Pune-based R&DE (Research & Development Engineers) played important roles in validating the tractor-cum-transporter-cum-launcher. A mobile missile system reduces vulnerability and allows for greater operational flexibility, while critics feel that the cost of these mobile systems could be higher and that they greatly increase the time for moving from one place to another.

DRDO’s Chief Controller of R&D (Missiles), Dr. A.S. Pillai, stated that Agni-I incorporates new guidance & control systems and there was also significant improvements in its re-entry technology and manoeuvrability. With only one stage, the weight is less but the thrust is the same, giving the missile more acceleration. As to it’s name of Agni-I, Dr. Pillai said it was christened so because it had a shorter range. When DRDO started the Agni project, it was part of the Integrated Guided Missile Development Program (IGMDP) and the first flight was intended as a technology demonstrator. After its successful completion, the Agni-II program was taken up. Since the range of the new missile lay between that of Prithvi-II and Agni-II, it was called Agni-I. The series is now called Agni, Agni-II and Agni-I, according to Dr. Pillai.

The requirements for the shorter range were met with some modifications to the Agni-II and instead of developing a new missile from scratch, DRDO decided to scale down the Agni-II, which has two solid stages. It used only the first stage and thus range has been reduced. Test and evaluation assumed more importance in the design of the missile, in concept validation and in terms of proving the systems for production of the missile. The first test, from a road-mobile launcher, was conducted on 25 January 2002 to a range of 700 km and was termed an accurate and successful flight which met its mission objectives. Additional tests may not be required, as the re-entry vehicle has been rigorously tested in its previous flights over all dynamic parameters, and the system may already be cleared for operational use. This strategic missile will join the Army and reportedly a Agni missile regiment is being raised for the purpose.

The Agni-I (photos left and right) mounted on a road-based mobile tractor-cum-transporter-cum-launcher. The diagram (above) shows the range of the Agni-I against Pakistan, at ranges of 700 km, 860 km and 1200 km. Being road and/or rail mobile, the missile won’t be prone to pre-emptive strikes and solid fuel ensures a quick and safe launch. All these combine to ensure a sound second strike capability.

During the test, the Agni-I missile was launched at a sub-optimal trajectory to reach an altitude of 300 km on a range of 700 km, corresponding to launch angle of 67º. The missile re-entered the atmosphere and splashed down in the Bay of Bengal. For the optimal 45º launch angle, the maximum altitude would be ~185 km and travel a range of 860 km in about seven minutes. With a special weapons load, Agni-I can reach 1200 km. The Agni-I MRBM missile has following operational superiority as compared to the Agni-II IRBM:

1. Lower cost: of unit procurement, ancillary support (trucks & storage building), maintenance and deployment (upgrading bridge, rail-stock).
2. Simplicity of single stage rocket: higher mission reliability improved safety, handling, operation, training & up-time (% time ready to be used).
3. More mobile: Easier & flexible deployment options.
4. More accurate (as compared to two-stage missile, i.e. Agni-II): higher effectiveness.
5. Stealth features: Smaller less conspicuous main and support vehicles, and a stealthy re-entry vehicle (RV) - which is very difficult to detect and defeat by a first generation ABM system - makes it an effective second strike weapon.

New Data Points & Technical Aspects:

1. Unlike the Agni-II, the RV of Agni-I does not have fins, indicating use of a new method for RV manoeuvring.
2. The re-entry velocity is significantly lesser than the Agni-II and thus there is more room for terminal manoeuvrability, or conversely for original degree of manoeuvrability albeit with a heavier payload.
3. The shorter-range missile does not require additional velocity from RV-thrusters, saving fuel space & weight for additional electronic gear, decoy or bigger payload.
4. The single-stage Agni-I with 12 ton GLOW (Gross Launch Overall Weight), is estimated to have combined RV & Payload weight of 2T, which appears heavier than the Agni-II. This may be useful for additional avionics, decoys or a heavier conventional payload.

Performance Aspects:

a) Given the strategic role of Agni-I, lack of fins on the RV and from item 2 above, the missile RV-body has greater terminal flight control envelop for better overall accuracy, not to mention additional improvement due to better navigational accuracy at shorter ranges.
b) From items 1 & 4 above, the Agni-I likely has a RV thruster for re-entry control and terminal steering, enabling a wider flight control envelope for better accuracy.
c) From item 1 above, the Agni-I is expected to have a smaller RCS signature, which makes detection by radar even more difficult.

Strategic Aspects of Agni-I Evolution:

On political aspects, the decision to develop Agni-I was the result of a discussion on the need to have a intermediary range missile between the short range Prithvi-II (250 km) and the longer range Agni-II (2500 km). The discussion was initiated in June 1999 at the height of the Kargil imbroglio. The concern was that advanced deployment of the Prithvi could be misinterpreted as lowering the nuclear threshold. Yet press reports after the crisis was resolved, indicated that four Prithvis and one Agni were activated. Obviously the misinterpretation would not have happened if sufficient Agni missiles were around for the task or these were tasked for other targets. Also there is the question of minimum range for the Agni which precluded more of them being tasked as a result of the Kargil crisis. Hence the need for the intermediary missile.

Soon after in late June 1999, Prime Minister Nawaz Sharif went to Washington D.C. and agreed to withdraw Pakistani troops from the heights of Kargil. The decision was taken in October 1999, which is a full three months after the discussion was initiated. This period must have been spent in trade studies to determine the feasibility of designing such an intermediary missile. K. Santhanam in an interview to ‘Times of India’ stated that it took 15 months to develop the missile and its road-mobile launcher. This indicates Agni-I development was over by December 2000. News reports indicate that the missile was ready for testing in December 2001 but was postponed twice to ease tensions. Either this was a development flight to qualify the missile or was done to proof the batch by confirmatory testing. It could be the latter as a statement by DRDO after this test, suggested speedy deployment in the armed forces.

On technical aspects, Agni-I design is said to have used existing sub-assemblies of the Agni-II vehicle with modifications. In addition the closed loop guidance scheme for the missile trajectory was worked out. Some of the airframe and sub-assemblies were reworked due to the higher boost phase accelerations for this intermediary missile compared to the Agni-II. This is true for the RV on Agni-I, since it will see much higher accelerations due to the reduced overall mass of the vehicle. We can infer that the RV has been qualified now for higher accelerations than on the Agni-II and this has implications for the planned longer-range missiles (Agni-III). It has been stated that Agni-III is in development and is rail-mobile as opposed to road-mobile and has a range of 3500 - 4000 km and its first test may occur in late 2003. Experts have commented on the reactive nature of the Indian system in developing this missile. However the IGMP was successful due to its close interaction with the armed forces and the fact that the low range of the Prithvi could be viewed as de-stabilizing is an indication of the cursory nature of strategic assessment by various interests - DRDO and the armed forces.

Since arms control issues were involved it would be interesting to find out the involvement of the MEA experts in this matter. Another issue to pick a bone with is the reason for the Prithivi program. From “Wings of Fire” (by Dr. APJ Abdul Kalam) it is clear that the project was implemented as a morale booster for disheartened scientists in DRDL who had worked on a previous program named Devil. And after the first flights it developed its own constituency. It is a sorry state of affairs when a weapons system implemented as a morale booster, ended up creating heartburn about lowering the nuclear threshold. Someone higher up should have stepped in long ago and come up with a less destabilizing system. It only goes to show that special weapons are complex systems and have deeper ramifications that have to be understood before proceeding.


1. India has an intermediary range missile which can be deployed far away from pre-emptive strike zones and could be activated without lowering the nuclear threshold. It is based on a solid fuel vehicle, which reduces the time factor for assured retaliation. Thus it enhances the credibility of the deterrent.
2. India has an RV and sub-assemblies that have been qualified for higher accelerations than the Agni-II vehicle. This implies these can be used on longer range vehicles as needed.
3. Agni-I is very accurate as it uses the Agni-II guidance sub-systems over shorter range, and better RV configuration for extended flight control envelope.
4. The Indian system can and does react in a quick manner to immediate threats. It has to strengthen its review process and ensure participation of all stakeholders.

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