Sir ,
I want to ask a doubt after hesitating s lot because may be it could be answered 100th on this thread but still,
Ballistic missiles can reach upto mark 24 (like agni). So how this thing is so different if it is not cruise missile and why there is so much shout about it because there are several quasi ballistic missiles too. Is it just about the fact that it is a ballistic missile that can reach hypersonic speeds and maneuver a bit in end game like a quasi ballistic missile.
Apologies if you have answered this question already.
Thank you
To answer your question from a technical standpoint, the main difference between ballistic and cruise missiles, is that ballistic missiles exit and re-enter the atmosphere, at least the lower 70% of it, thus gaining a LOT of speed in intra-atmospheric stage & then reaching mach 24 or such absurd speeds in terminal velocity phase under gravity.
Remember, for ballistic missiles to go terminal velocity, its trajectory, not range that matters, since in ALL ballistic motion, velocity *MUST* equal 0 at apogee, before the object moves to its terminal trajectory.
In this phase,what you basically have, is an ultra-high speed bullet, which you can steer to a degree with glide properties. You could even strap on a small engine to it to give it more controllable thrust or thrust nozzles and fancy stuff, but basically you are operating on glide properties, with the governing speed coming from terminal velocity of simple projectile motion physics.
Now in cruise missiles, its basically a rocket going sideways through the atmosphere, where its gaining ALL of its speed via continuous thrust output of its rocket motor ( a ballistic missile warhead gets no more thrust output after apogee, then its just gravity that takes over). This is basically your loony tunes cartoon rocket car, that can do crazy things in terms of speed and manueverability as long as the crazy engine is on and has fuel.
Now, since cruise missiles are not trans-atmospheric, they offer certain discrete advantage : low detectability ( basically no detectability across the horizon and you need to keep raising the horizon to see it coming, meaning keep flying further and further up with a missile detection system, instead of having a radar on ground detecting trans-atmospheric entry from 5000kms away) being one.
Another one is, ability to do sophisticated terminal phase manuevers, because it still has thrust output into its terminal phase, meaning controlling thrust output velocity yeilds sophisticated evasion and re-targetting patterns.
The main trade-off is range, because a cruise missile travelling from point A to point B is travelling 100% of its trajectory through the dense lower atmospheric air, thus creating a huge amount of drag. As opposed to a ballistic missile, that does trans-atmospheric trajectory, it means it spends only a tiny % of its trajectory through thick lower atmosphere, thus expericing significantly less drag over time.
Now you can hybridize either model to a degree, but overall, the governing physics remains the same basically due to the whole 'where is the projectile getting most of its kinetic energy/momentum from in its terminal phase' angle.
