260" SRM - as an ICBM

[Christopher Wang]

Would the 156-inch and 260-inch ICBMs have used a cold launch system?

 

[publiusr]

I can't imagine what it'd take to thump those things upwards.

They would have more general overall utility to humanity than SLBMs that can only kill.

 

[Byeman]

I can't imagine what it'd take to thump those things upwards.

They would have more general overall utility to humanity than SLBMs that can only kill.

not true.
a. older SLBM's are used as sounding rockets and target launchers.
b. 260" has no utility

 

[Dilandu]

In pure theory, if you could combine a bunch of 260-inch boosters with another as central/upper stage, it could be a delivery vechicle for Teller's gigaton-scale "skyburner" superbombs...

 

[Scott Kenny]

I can't imagine what it'd take to thump those things upwards.

A gas generator that makes roughly the total stack weight in thrust for a fraction of a second, if I understand the basics correctly.

Which sounds terrifying but isn't that bad since you use a superexpansion rocket nozzle to get the temps and pressures down.

 

[Yellow Palace]

A gas generator that makes roughly the total stack weight in thrust for a fraction of a second, if I understand the basics correctly.

You presumably need to exceed the stack weight, that being how physics works, and provide enough energy to lob the thing out of the silo to whatever height you've deemed safe for main stage ignition. It's presumably similar to an interior ballistics calculation.

 

[Scott Kenny]

You presumably need to exceed the stack weight, that being how physics works, and provide enough energy to lob the thing out of the silo to whatever height you've deemed safe for main stage ignition. It's presumably similar to an interior ballistics calculation.

That "enough energy to lob the thing clear" part usually comes from further expanding gasses continuing to push.

I'd also assume that it's basically an interior ballistics calculation.

The gas generators for a Trident are about the size of a water heater. So yes, whatever you'd need for a 260" monster rocket would be a lot bigger than that, but mostly in terms of diameter not length. So, more like a hot tub full of solid rocket fuel instead of a water heater.