On 25 August 2026, CSIR-National Aerospace Laboratories (CSIR-NAL) unveiled three indigenous micro and small gas turbine engines at the SSB Auditorium, CSIR Headquarters, New Delhi: the NJ-05 rated at 5 kg thrust, the NJ-50 at 50 kg and the NJ-100 at 100 kg. They are intended for tactical unmanned aerial vehicles, drone interceptors and compact missile systems.
The chief guest was Air Marshal Tejinder Singh, Chief of Integrated Defence Staff to the Chairman, Chiefs of Staff Committee (CISC). Dr N. Kalaiselvi, Director General of CSIR and Secretary, DSIR, and Dr Abhay A. Pashilkar, Director of CSIR-NAL, also spoke; the technical presentation was made by the team led by Shri R. Prathapanayaka, covering advances in high-RPM turbomachinery and high-temperature combustion.
Why a 100-kilogram engine is a bigger deal than it sounds
Numbers this small invite the wrong reaction. A 100 kg thrust engine is roughly a thousandth of what powers a fighter aircraft. But the class matters for a specific reason: it is the propulsion class of everything that is currently changing about warfare.
A loitering munition, a jet-powered target drone, a drone interceptor and a compact cruise missile all need an engine that is small, light, cheap enough to be expendable, and capable of starting reliably after long storage. Piston engines and electric propulsion cannot deliver the speed; a full-size turbofan is absurdly oversized and expensive. The gap is filled by micro and small gas turbines — and India has largely been buying them, which places a foreign supplier inside the supply chain of a category of weapon that is consumed in quantity.
That is the strategic argument, and it is more precise than the usual self-reliance phrasing: the problem with importing an expendable weapon's engine is not cost but volume. You can stockpile a few imported engines for a prestige platform. You cannot fight a drone war on an import licence.
How a gas turbine works, in the form NDA questions ask
The physics is standard and worth having cleanly, because it is examinable independent of the news.
A gas turbine runs on the Brayton cycle, in four stages:
- Intake — air enters.
- Compression — a compressor raises the pressure, and with it the temperature.
- Combustion — fuel is burned at roughly constant pressure, sharply raising temperature.
- Expansion and exhaust — hot gas expands through a turbine, which drives the compressor; the remaining energy leaves as a high-velocity jet.
Thrust comes from Newton's third law: the engine accelerates a mass of air rearward, and the reaction pushes the aircraft forward. Thrust is the rate of change of momentum imparted to the flow — so an engine can produce thrust either by moving a lot of air slowly or a little air very fast.
That single sentence explains the turbojet versus turbofan distinction:
| Turbojet | Turbofan | |
|---|---|---|
| Airflow | All air passes through the core | A bypass stream goes around the core |
| Character | Little air, very fast | Much air, moderately fast |
| Best at | High speed, small frontal area | Fuel efficiency at subsonic speed |
| Typical use | Missiles, small jet UAVs | Airliners, most modern fighters |
Small expendable systems generally use turbojets, because simplicity, compactness and cost matter more than fuel economy over a short flight. The NJ designation of these engines is consistent with that family.
Why small is hard — the counterintuitive part. Scaling a gas turbine down does not make it easier. As the engine shrinks:
- Rotational speed must rise — small turbomachinery runs at extreme RPM, which is why the team's presentation highlighted high-RPM turbomachinery as an advance in its own right. Bearings, rotor dynamics and balancing all become harder.
- Clearances become proportionally larger. The gap between blade tip and casing cannot shrink indefinitely, so a small engine loses proportionally more air through leakage, hurting efficiency.
- Surface-area-to-volume ratio rises, so more heat is lost through the walls of the combustor, making stable high-temperature combustion harder to sustain — the second advance the team named.
Small gas turbines are, in short, not scaled-down big ones; they are a distinct engineering problem. This is exactly why so few countries make them well.
The honest context: India's aero-engine gap
A complete answer should place this achievement accurately rather than overstate it.
India's difficulty with large aero-engines is long-standing and unresolved. The Kaveri engine, developed by DRDO's Gas Turbine Research Establishment (GTRE) in Bengaluru from the 1980s, was intended to power the Tejas Light Combat Aircraft but did not meet the required thrust and weight targets; Tejas flies on an imported engine, and the search for a partner to co-develop a high-thrust engine for future fighters continues. Note the organisational distinction, which is a likely question: GTRE is DRDO; CSIR-NAL is CSIR. Both work on propulsion, and they are not the same body.
So the correct framing of the 25 August announcement is: India has demonstrated indigenous capability at the small end of the thrust spectrum, which is genuinely valuable and directly relevant to drone warfare — while the large-engine gap remains open. Both halves of that sentence are true, and a candidate who states both is being accurate rather than pessimistic.
CSIR-NAL itself is worth knowing: based at Bengaluru, it is the CSIR laboratory for aerospace, and its programmes include the SARAS light transport aircraft and the HANSA trainer. Director Dr Pashilkar described the lab's evolving role as a multi-stage integrator for India's drone ecosystem, and pointed to the aerospace start-up sector as the likely route to manufacturing these engines at scale — the same public-lab-to-private-manufacture pathway that appears across defence and technology current affairs, and whose underlying physics belongs with the study of work, energy and power.
🔑 Revision block
The event. 25 August 2026 — CSIR-NAL unveiled three indigenous micro and small gas turbine engines at CSIR Headquarters, New Delhi.
The engines. NJ-05 — 5 kg thrust · NJ-50 — 50 kg · NJ-100 — 100 kg. For tactical UAVs, drone interceptors and compact missile systems.
Who was there. Chief guest Air Marshal Tejinder Singh, Chief of Integrated Defence Staff to the Chairman, Chiefs of Staff Committee (CISC). Dr N. Kalaiselvi, DG CSIR and Secretary, DSIR. Dr Abhay A. Pashilkar, Director, CSIR-NAL. Technical team led by Shri R. Prathapanayaka.
The two technical advances named. High-RPM turbomachinery and high-temperature combustion.
The Brayton cycle. Intake → compression → combustion at roughly constant pressure → expansion through the turbine and exhaust. The turbine drives the compressor; the rest of the energy leaves as a high-velocity jet.
Thrust. By Newton's third law — the engine accelerates air rearward. Thrust can come from a lot of air slowly or a little air very fast.
Turbojet versus turbofan. Turbojet — all air through the core, little air very fast, good at high speed, used in missiles and small jet UAVs. Turbofan — a bypass stream around the core, much air moderately fast, fuel-efficient at subsonic speed, used in airliners and most fighters.
Why small is hard. RPM must rise as size falls (bearings, rotor dynamics, balancing) · tip clearances become proportionally larger, so leakage losses grow · surface-area-to-volume ratio rises, so heat loss makes stable combustion harder. Small gas turbines are not scaled-down large ones.
The strategic point. Expendable weapons are consumed in volume — an imported engine is tolerable for a prestige platform, impossible for a drone war.
The honest gap. The Kaveri engine, by DRDO's GTRE (Bengaluru), was intended for Tejas but missed thrust and weight targets; Tejas flies on an imported engine. GTRE is DRDO; CSIR-NAL is CSIR — different organisations. India now has small-engine capability; the large-engine gap remains open.
CSIR-NAL. Based at Bengaluru; programmes include SARAS (light transport) and HANSA (trainer). Positioning itself as a multi-stage integrator for the drone ecosystem, with aerospace start-ups as the manufacturing route.
🎯 Practice MCQs
Q1. The engines unveiled by CSIR-NAL are rated at: (a) 5 kg, 50 kg and 100 kg thrust (b) 5, 50 and 100 kN (c) 500 and 1,000 kg (d) 5 and 10 tonnes → (a) — NJ-05, NJ-50 and NJ-100.
Q2. CSIR-NAL is headquartered at: (a) Bengaluru (b) Hyderabad (c) New Delhi (d) Pune → (a).
Q3. A gas turbine engine operates on which thermodynamic cycle? (a) Brayton (b) Carnot (c) Rankine (d) Otto → (a) — Rankine is the steam cycle, Otto the petrol engine cycle.
Q4. In a turbofan, the air that bypasses the core: (a) provides much of the thrust at high efficiency (b) cools the cabin (c) is used for combustion (d) is discarded → (a).
Q5. Jet thrust is explained by: (a) Newton's third law (b) Bernoulli's theorem alone (c) Archimedes' principle (d) Boyle's law → (a).
Q6. The Kaveri engine was developed by: (a) DRDO's Gas Turbine Research Establishment (b) CSIR-NAL (c) HAL alone (d) ISRO → (a) — intended for the Tejas LCA.
Q7. Which of the following makes miniaturising a gas turbine difficult? (a) Tip clearances become proportionally larger (b) Air becomes denser (c) Fuel burns slower (d) Thrust rises automatically → (a) — along with higher RPM and greater heat loss.
Q8. Small expendable systems typically use turbojets rather than turbofans because: (a) simplicity and compactness matter more than fuel economy (b) turbofans cannot exceed subsonic speed (c) turbojets are quieter (d) turbofans need no compressor → (a).
Q9. CISC, whose head was chief guest, stands for: (a) Chief of Integrated Defence Staff to the Chairman, Chiefs of Staff Committee (b) Central Indian Security Command (c) Chief Inspector of Services and Commands (d) Combined Intelligence Support Cell → (a).
Q10. The Director General of CSIR is concurrently the Secretary of: (a) DSIR (b) DRDO (c) DAE (d) DST → (a) — the Department of Scientific and Industrial Research.
Q11. Aircraft programmes associated with CSIR-NAL include: (a) SARAS and HANSA (b) Tejas and Rudra (c) Dhruv and Prachand (d) Netra and Rustom → (a).
Q12. In the Brayton cycle, combustion occurs at approximately constant: (a) pressure (b) volume (c) temperature (d) entropy → (a) — constant-volume combustion characterises the Otto cycle.
📋 How this gets asked (PYQ pattern)
Aerospace-technology items reach the NDA paper through four doors, and this announcement touches all of them. The cycle item — matching Brayton, Otto, Diesel, Rankine and Carnot to their machines, which is a physics question asked in a defence costume and one of the most reliably repeated in the science section. The organisation item — DRDO, CSIR, ISRO and HAL and their laboratories, where GTRE under DRDO versus NAL under CSIR is exactly the confusion an examiner exploits. The programme item — Kaveri, Tejas, SARAS and HANSA matched to their developing agency. The propulsion item — turbojet against turbofan against turboprop, distinguished by bypass and by use case.
The fresh 2026 hook is the NJ-05/NJ-50/NJ-100 trio and their thrust ratings, likely asked as a straightforward recall item, with the developing organisation as the second half of a statement pair. As always, we describe the recurring pattern, not any exact past question.
Preparing for the NDA? Technology news is most useful when it anchors a physics concept you are already learning — an engine announcement is a free revision of the Brayton cycle. Reinforce the mechanics with our notes on work, energy and power and the NDA general knowledge hub, follow the daily NDA current affairs, and train with our ex-officer faculty in the upcoming Cavalier courses in Delhi.
✍️ Written by Col D.N. Sharma — Defence studies & technology faculty at The Cavalier. Reviewed by the Cavalier Faculty Desk. The Cavalier, founded by ex-Army officers, has trained NDA/CDS/SSB aspirants since 2001 (Facebook · YouTube).
Source: PIB / Ministry of Science & Technology, 25 August 2026. Engine and programme details cross-verified with independent sources.