What are the Differences between a Ballistic Missile and a Cruise Missile?

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Both classes were first used by Nazi Germany in WW2: the V1 was a cruise missile, while the V2 was a ballistic missile. The operation modes of both missiles are radically different, but modern missiles, if well used, can be highly effective, no matter if it’s a cruise or ballistic missile.

A ballistic missile is closer to the rockets used to launch satellites – in fact, some rockets were former missiles,and some missiles were initially projected (covertly or not) to be rockets. Ballistic missiles climb very high, exiting the atmosphere.

It’ s relatively easy to detect a ballistic missile after launch, but intercepting them is very challenging due to their sheer speed (as an example, the Russian RS-28 Sarmat ICBM can reach almost 25,000 km/h, or well over 15,000 mph).

To further complicate matters, most ICBMs carry not a unitary large warhead, but several smaller and fully independent nuclear missiles called MIRVs (Multiple independently targetable reentry vehicle). The Sarmat can carry up to 24 MIRVs. Each MIRV carries nuclear warheads with yields ranging anywhere from hundreds of kilotons to a few megatons.

MIRV launch sequence: 1. The missile launches out of its silo by firing its first-stage boost motor (A). 2. About 60 seconds after launch, the 1st stage drops off and the second-stage motor (B) ignites. The missile shroud (E) is ejected. 3. About 120 seconds after launch, the third-stage motor (C) ignites and separates from the 2nd stage. 4. About 180 seconds after launch, third-stage thrust terminates and the post-boost vehicle (D) separates from the rocket. 5. The post-boost vehicle maneuvers itself and prepares for reentry vehicle (RV) deployment. 6. While the post-boost vehicle backs away, the RVs, decoys, and chaff are deployed (this may occur during ascent). 7. The RVs and chaff reenter the atmosphere at high speeds and are armed in flight. 8. The nuclear warheads detonate, either as air bursts or ground bursts.

Real image of MIRVs in end stage during a test. Each MIRV lets a trail of fire behind it, as the temperatures resulting from the friction with the atmosphere are enormous.

Each MIRV can hit a target hundreds of kilometers away from each other, and some MIRVs will carry decoys and countermeasures, putting additional stress on defensive systems. SRBMs usually carry conventional payloads, but chemical weapons are theoretically possible.

Ballistic missiles and MIRVs can’t maneuver very well, they are basically straight line fliers. But their sheer velocities make it very difficult to defend against them.

10 MIRVs of a Peacekeeper ICBM

Cruise missiles, on the other hand, are essentially “kamikaze drones”. Most cruise missiles are subsonic, with a few supersonic cruise missiles around. The most complex cruise missiles are arguably those of the Tomahawk class, and some of similar characteristics.

Such missiles usually fly at extremely low altitudes, and many of them can follow through way points. The low altitudes they usually employ significantly reduce radar detection range (due to the Earth’s curvature), and the way points make it very hard to define its exact rout and targeting area.

Cruise missiles can also carry nuclear payloads (usually unitary payloads) of simmilar yield of MIRVs. To date, and thank God, only conventional warheads have been used in cruise missiles.

BrahMos is a supersonic cruise missile. It can’t fly as low or maneuver as hard as subsonic missiles, but its speed (more than Mach 2.5) makes it extremely difficult to defend against.

Most cruise missiles have a range of less than 300 km, with the longer ranged ones barely reaching 1600 km.

This article is written by Renato Henrique Marçal de Oliveira on Quora.