Rockets of Today

LVM 3 — formerly GSLV MARK III — India, 2014

The rocket that’s now called LVM 3 was originally called Geosynchronous Satellite Launch Vehicle, Mark III. That name implied that it was just a minor update of the GSLV Mark II or Mark I, which had only slight differences between them, and were themselves just a spinoff of India’s venerable PSLV. But the GSLV III is entirely different from the GSLV I and II, with almost no common ground other than the name. Because of the name, the LVM 3 was originally written up as part of the PSLV article, though it was an awkward fit there.

So what’s the new name in full? “Launch Vehicle Mark 3”. And there is no Launch Vehicle Mark 2. The only name more generic is Astra’s Rocket 3.3 or 4.0.

In 2023 they launched their Chandrayaan-3 lunar lander on a rocket that they designated as “LVM3-M4”. Is this sort of a stealth Mark IV? No idea.

What is this all-new rocket like? It’s quite a bit bigger than the old ones — India’s largest and most ambitious rocket, which the engineers openly refer to as “the Fat Boy”. Its core stage burns hypergolic fuel in a pair of independently gimballed Vikas-2 engines, and it has two big fat solid boosters on the sides, giving it a silhouette similar to an Ariane 5. These boosters (which are each substantially bigger than the core stage of a PSLV) have steerable nozzle extensions. Unusually, the core stage does not ignite at liftoff, but near the time of booster separation. This lets its engines use larger bells, improving efficiency. The upper stage burns hydrogen, so once again we have a mix-and-match assortment of fuels, though this time it adds up to a much more conventional overall picture than we saw in the earlier rockets, which had some odd and unusual design choices in them. As hydrogen burning upper stages go, this is a powerful one, and no further stage is needed. It may sound less advanced than the Mark II upper stage, which had a staged-combustion cycle, while the new one is a gas generator... but that’s because the Mark II engine is a copy of a little Russian motor which they imported and used in the Mark I, while the Mark III engine is all-Indian, and much more powerful.

RLV / Pushpak

The LVM-3 is their path toward a much more ambitious space program than they previously had.  The rocket’s maiden suborbital test flight was used to test a heat shield for a future “Gaganyaan” crew capsule. They’re experimenting with a reusable rocket with the interim name of RLV, and also with a scramjet. The RLV would not only have a vertically-landing first stage, but a spaceplane second stage, and they have been doing drop tests to work on the automated landing. They recently showed off the plane and announced that RLV would have a new name: Pushpak (पुष्पक), after a mythical flying palace. They’re also opening new space agency facilities. India is taking spaceflight very seriously. They want to show in time that they can match anything offered by China. They hope to send a crew of three “gagannauts” into orbit in 2024. And there’s talk of a bigger reusable rocket tentatively named Soorya, which would obsolete the LVM-3 and maybe even be capable of sending gagannauts to the moon. But that won’t be ready until the 2030s.

But the LVM-3 has been moving slowly, with less than one launch per year. And unfortunately the last few years have been tough. A failed lunar mission that had them postponing all other work, followed by a major hit from the covid pandemic, have put the space agency ISRO far behind where it hoped to be. For a while they were almost completely shut down. But they are now making a comeback. As part of that, the LVM-3 has now started doing commercial launches, putting up a batch of OneWeb sats which were originally supposed to ride a Soyuz. I would not bet against ISRO long term... but I also won’t put much stock in their planned dates, any more than I do for private startup companies.

Such misgivings are unimportant. The big picture is that this “fat boy” has legitimately elevated India to the status of the newest major power in space, comparable to Japan or the EU. Before long they may be in a position where you could argue that the Russians are falling behind them! We’ll see.

LVM-3: mass 640 t, diam 4.0 m (width ~10.5), thrust 10300 kN?, imp 2.9 km/s, gas generator (UDMH blend) and solid fuel, payload 10 t (1.6%), cost $6M/t, record 6/1/0 through 2023.
Stage name S200 L110 C25
Role (pos) count booster (S/1) ×2 core (2) * upper (3)
Diameter (m)   3.20   4.00   4.00
Liftoff mass (t) 237    125    33  
Empty mass (t) 31.2  8.9  5.1
Fuel mass (t) ~62    ~43    ~4.6
Oxidizer mass (t) ~144     ~73    ~23.3 
Fuel type HTPB UDMH+HH * hydrogen
Engine S200 Vikas-2 ×2 C25
Power cycle solid gas gen gas gen
Chamber pres. (bar) 57   59   60  
Ox./fuel ratio   2.3?   1.71   5.05
Thrust, vac max (kN) 5150     1678     200   
Thrust, SL initial (kN) 4330?    1513    
Spec. imp, vac (km/s)   2.60   2.90   4.40
Total imp, vac (t·km/s) 555    345    121