How do I prevent a long and thin missile that enters the atmosphere of Kerbin at 4500 m/s from exploding?

[MedwedianPresident]

I have succesfully constructed an Orbital Bombardment System sattelite that sends medium-sized missiles (that consist of an 0.625m SRB, a probe core and a nosecone) towards Kerbin's surface. Everything worked well during the launch and the deployment. However, the missiles explode immediately due to overheating upon entering Kerbin's atmosphere.

 

Is there any workaround for this that does NOT involve cheating by decreasing reentry heat? What can I change in the construction of the missiles? Are there any mods which offer 0.625m heatshields or protected ablator nosecones? I have FAR installed so I want to keep the cross-section of the missile as small as possible to allow for higher impact speeds.

 

Here, the sattelite and the missiles are shown. The whole construction would usually have a protective casing that is not shown here for visibility purposes.

 

[fourfa]

Try the magic antenna trick.  Take the Communotron 16, place it dead center of the nose cone pointing out (probably need to use the rotate/offset gizmo), and extend it.  It creates a detached shock zone that keeps heat away from the nose cone itself, but somehow doesn't blow itself up.

[MedwedianPresident]

Will try this. I hope that it works with FAR.

[James Kerman]

You could also try reversing a heat shield (remove the ablator as you don't need it) and place it under the nosecone.

[Snark]

You could use ModuleManager to mod the nosecones so that they have some ablator.

[The_Rocketeer]

Why are they entering the atmosphere so fast? All u really need to do is aim retrograde and burn enough solid fuel to kill your orbital velocity so your missiles fall straight towards whatever's on the surface below them - from LKO (less than 100km) they'd probably survive that.

Think of it like your first sub-orbital hop in career - the danger to the ship at this stage is usually going too fast for the chutes to deploy, not burning up from re-entry heating.

Edited August 9, 2016 by The_Rocketeer

[bewing]

If you put blunt noses on the rockets rather than pointy ones, that will always help things survive reentry, because of the detached shockwave effect.

Also, you want the noses to be reasonably massive -- not light. A massive object can conduct and absorb heat, in a way that an insubstantial part cannot. So a simple 1.25m heatshield with some amount of ablator might be a good idea. You'd need to experiment with the ablator to find out how much you need. The nice thing about that is that the heatshields have low drag, so your impactors won't slow much.

So my basic advice is to ditch the nosecones, because they are actually counterproductive.

 

 

Edited August 9, 2016 by bewing

[MedwedianPresident]

2 hours ago, bewing said:

If you put blunt noses on the rockets rather than pointy ones, that will always help things survive reentry, because of the detached shockwave effect.

Also, you want the noses to be reasonably massive -- not light. A massive object can conduct and absorb heat, in a way that an insubstantial part cannot. So a simple 1.25m heatshield with some amount of ablator might be a good idea. You'd need to experiment with the ablator to find out how much you need. The nice thing about that is that the heatshields have low drag, so your impactors won't slow much.

So my basic advice is to ditch the nosecones, because they are actually counterproductive.

 

 

The sattelite would have to be completely redesigned to accommodate 1.25 m missiles. Is there any mod lying around which offers 0.625 m heatshields? If yes, it would be great. If I will have to use 1.25ers though and my missiles will still be 0.625 SRB's, I will have to ditch the heatshield when the heating would stop being dangerous so that no velocity is wasted. After all, the missiles are supposed to be high-speed kinetic impactors and not burned-out SRB's that slowly tumble towards the surface!

However, I agree that the missiles should certainly be nose-heavy.

 

3 hours ago, The_Rocketeer said:

Why are they entering the atmosphere so fast? All u really need to do is aim retrograde and burn enough solid fuel to kill your orbital velocity so your missiles fall straight towards whatever's on the surface below them - from LKO (less than 100km) they'd probably survive that.

Think of it like your first sub-orbital hop in career - the danger to the ship at this stage is usually going too fast for the chutes to deploy, not burning up from re-entry heating.

If I'll burn retrograde and let them fall vertically I'll loose to much time and speed. I want them to enter the atmosphere at 4.500 m/s a.) because they are supposed to reach their target in the shortest possible time to prevent the deployment of countermeasures, b.) it is harder to shoot down a missile coming in at 4.500 m/s than one  that is coming in at 900 m/s. and c.) because they are kinetic impactors and ideally should impact the ground at the highest possible velocity. In the very ideal case, they would soar through the stratosphere in seconds, not having time to brake, and impact the surface at at least 1.000 m/s.

 

7 hours ago, fourfa said:

Try the magic antenna trick.  Take the Communotron 16, place it dead center of the nose cone pointing out (probably need to use the rotate/offset gizmo), and extend it.  It creates a detached shock zone that keeps heat away from the nose cone itself, but somehow doesn't blow itself up.

I will try this. I think that it is even used IRL and I hope that it will work with FAR.

[fourfa]

3 minutes ago, MedwedianPresident said:

 

Tweakscale is pretty simple, and lets you downscale 1.25m heat shields to .625

[bewing]

Also, there is a mod that has "procedural heatshields" -- called Procedural Parts. Procedural heatshields are also sizeable.

[The_Rocketeer]

6 hours ago, MedwedianPresident said:

...impact the surface at at least 1.000 m/s.

It's been my experience that practically anything travelling faster than about 1600m/s at or below 16000m is doomed to spontaneous and complete obliteration - including heat shields, IIRC.

I will be fascinated to see how you did it if u can pull this off, but I also have to say I don't think it can be done.