Orbital Bombardment Systems

[MedwedianPresident]

Recently, I've been thinking about two concepts for Orbital Bombardment Systems (OBS). The first one is the generic OBS setup, with a sattelite armed with (usually SRB-powered and barely controllable) missiles that orbits Kerbin at an altitude of around 80 to 150 kilometers. The second one is a sattelite that orbits Kerbin at 70-73 km (barely above the edge of the atmosphere) and that releases hypersonic guided or unguided bombs which enter the atmosphere at a very shallow angle and glide towards their target while maintaining a very high speed (should be possible with FAR).

While at least the first concept has been implempted into the game in the form of OBS's that are purely cosmetical (e.g. you just fire a missile and it hits Kerbin at a random point), the 2 main requirements for good OBS concepts are as follows:

 

1. Targeting

Missiles or bombs should hit a predetermined target. The mod "Trajectories" makes it possible to predict aerodynamic descent pathes, but the difficult part is actually achieving a planned trajectory. There are two possibilities for hitting targets: if your missile has high delta-V, you can just fire directly at the target and hit it at horrendous speeds (but don't expect good accurancy, probably only good if the job needs to get done fast or if you are using a WMD), or, if your missiles have less delta-V and if you want more precision, deorbit the missile and then re-align it to enter the atmosphere safely after the engine burns out.

If you have hypersonic bombs, then you probably won't need propulsion at all but simply some aerodynamic surfaces (or none if you have FAR) and change the orientation to correct the trajectory. This concept will also require for the low orbiter to change inclinations constantly or only target equatorial targets.

 

2. Service and resupply of the sattelite

A standard OBS usually packs less than 10 missiles - if it is not a "one use" sattelite that is deorbited after running out of missiles, it somehow must be restocked with new missiles. It is of course easy to put those new missiles into space, but the hard part is actually putting them in place. Manipulator arms or other advanced mechanical applications may be needed for this.

 

 

Feel free to post your ideas concerning orbital bombardment systems or your builds here.

[Joco223]

You can watch a video a think Scott Manley did on it. He did create something similar to the second idea that you mentioned

[XB-70A]

About the "Service and resupply of the sattelite" question, I will go for a design like a barrel speedloader. Each projectiles will be connect to a common center which will be separated from the main plateforme after the last round is drop. A new complete barrel will be connected soon after. This would prevent the system to be operational for a while during the reload but would simplify the process, and as most (if not all) OBS are reserved to strategic situations with pre-defined targets this is not so much a problem.

[Talos]

Reminds me of the Soviet FOBS system, where the ICBM would go into LEO then deorbit when needed.

[razark]

6 hours ago, XB-70A said:

Each projectiles will be connect to a common center which will be separated from the main plateforme after the last round is drop.

Give that common center a deborbit and guidance system, and you've got one extra round, as well.

Although, I don't see the benefit to making a reloadable rather than a single-use system.  The OBS bus would be a rather small part of the total system.  Maybe you could build a reconnaissance system into the bus for additional usage while waiting for a strike mission, and post-strike analysis afterwards.

[MedwedianPresident]

19 minutes ago, razark said:

Give that common center a deborbit and guidance system, and you've got one extra round, as well.

Although, I don't see the benefit to making a reloadable rather than a single-use system.  The OBS bus would be a rather small part of the total system.  Maybe you could build a reconnaissance system into the bus for additional usage while waiting for a strike mission, and post-strike analysis afterwards.

So you mean a telescope attached to the sattelite that is used for targeting?

 

I think that for sattelites which have more than 8-10 missiles, reloading would be appropriate, while FOBS-style ICBM's that remain in orbit only for a few days will of course be single-use apparata.

[razark]

2 hours ago, MedwedianPresident said:

So you mean a telescope attached to the sattelite that is used for targeting?

Not necessarily for targeting.  More as a secondary capability to take pictures of anything that needs its picture taken.

 

Aside from equipment giving it a secondary mission, what is the bus going to contain that makes it that much easier to reload rather than replace it?

[MedwedianPresident]

I am currently having problems with building an appropriate rocket for this project (everything I tried so far either did not have enough delta-v or had a very weak second stage or just wobbled around like a wet noodle and underwent disintegration upon commencing the gravity turn), but I will of course not forget about the structure of the sattelite itself.

I think that the missiles (which will be basically 1.25m SRB's) should be placed into a special casing made out of structural panels that has a protective lid which is either openable in the fashion of a space telescope or is jettisoned upon reaching the target orbit. The sattelite will also have a weak orbital engine and approximately 1.500 m/s of spare dV for inclination changes and other necessary maneuvers.

I think that it would be a good idea to put the whole sattelite (probe core, LF and RCS tanks, engine, missiles, targeting equipment) into an inline casing made out of 1x1 panels that resembles a 12-sided prism (using 6-fold symmetry). This would ensure stability and prevent wobbling and disintegration; maybe, the lid should have a heat shield on top of it to allow safe recovery of the sattelite.

Hm...I am actually wondering whether the sattelite should be resupplied in orbit or should regularly be deorbited to land at the launch site and be restocked before launch like a space shuttle.

The next problem to work on will be the structure of the missiles and guidance systems (I won't use MechJeb because it ruins the fun but maybe kOS?). kOS would be especially useful if you want to ignite the missiles not upon decoupling but when they have reached a safe distance from the sattelite (I will write a program that is automatically activated upon decoupling and that ignites the missile, say, after 10 seconds).

I think that the optimal launch profile will be a compromise between a classical retro-burn (too slow) and shooting directly at the target (requires insane thrust and dV). The missile will point neither retrograde nor directly at the target but in a vector in between these two, e.g. directly downwards if the target is at the horizon upon launch. This way, the missile will still speed up while changing its trajectory.

 

I'm on my iPad right now and it is past 3 AM. Will post pictures and graphics tomorrow; probably in a post at Fan Works or Mission Reports.

BTW, I'm using FAR; I hope that a very thin and long projectile will have a high terminal speed. When BD will be fixed for the current KSP version (Am I correct that it's currently broken?) I will stick explosive warheads onto the missiles.

[MedwedianPresident]

I'm also thinking of a name... maybe "Zeus" because that particular Greek god could fling lightning strikes?

[razark]

15 minutes ago, MedwedianPresident said:

I'm also thinking of a name... maybe "Zeus" because that particular Greek god could fling lightning strikes?

Zeus?  No.  If you're thinking about deity names, go with tradition:

https://en.wikipedia.org/wiki/Project_Thor

[MedwedianPresident]

Hm...yes, Thor or another Norse god sounds better.

Also, THOR and LOKI make better acronyms than ZEUS.

 

Tactical Hypersonic Orbital Retaliation system? Low Orbit Kinetic Impactor? What ideas do YOU have?

[MedwedianPresident]

Actually, THOR or THORP will be the name of the sattelite (maybe Tactical Heavy Orbital Restockable platform omething like that) while the (kinetic) missiles will be called LOKI (Low Orbit Kinetic Impactor).

 

Good idea?

[XB-70A]

5 hours ago, razark said:

Although, I don't see the benefit to making a reloadable rather than a single-use system.  The OBS bus would be a rather small part of the total system.  Maybe you could build a reconnaissance system into the bus for additional usage while waiting for a strike mission, and post-strike analysis afterwards.

My idea will be to load kinetic or conventional projectiles but, well, the sole concept of OBS (and their path which could be routed) is for more than forty years now out of date on the strategic plan, without counting the extremely limited possibility of daily targets which could be hit without changing the orbit.

And an OBS dedicated to tactical situations doesn't have any sens for the same reasons of limited shooting windows plus an infernal cost per rounds.

 

28 minutes ago, MedwedianPresident said:

another Norse god sounds better.

 

For a much more older war-divinity you could go for Týr/Ziu, less famous but also less deeply disfigured than Thor and Odin by a certain comic.

No. 6 of the 60 cm Karl-Gerät heavy self-propelled mortar got that name : 

The old-German name of Odin, Wotan, got a certain charm also.