Kinetic and Thermobaric Munitions

[GnyHwy]

An even crazier idea.  Check out Project Thor.  Launching tungsten telephone poles from space.  The incoming mass and velocity would likely be similar to a nuke while penetrating 100s of meters into the ground.

Crazy effective idea, but not very practical.  I wouldn't even begin to guess how much a tungsten telephone pole would cost, let alone the cost to get it into orbit.  Suddenly makes the guidance package seem cheap.

http://en.wikipedia.org/wiki/Kinetic_bombardment#Project_Thor 

 

[cupper]

Looking at thermobaric, is there a system available that would produce an effective result that would be feasible for use by troops on the ground? I know that there are man portable thermobaric weapons out there, but are there arty rounds or tank rounds on the market as well? Or is there a problem with the delivery system that precludes development of a thermobaric round? And failing all of the above, are we left with only thermobaric aerial bombs (guided or dumb) to achieve the best result?

 

[vonGarvin]

This is the 9K57 "Uragan" MLRS.  It's a Russian system.  It's very effective, but there is the whole "collateral damage" it can also cause.

Here's a promo video of it.

 

[vonGarvin]

And don't forget the 9K58 "Smerch":


Video

 

[cupper]

Cool. I didn't think about the rocket option for arty.

Any thoughts on development of a shell that can deliver a thermobaric payload?

 

[McG]

Looking at thermobaric, is there a system available that would produce an effective result that would be feasible for use by troops on the ground? I know that there are man portable thermobaric weapons out there, but are there arty rounds or tank rounds on the market as well? Or is there a problem with the delivery system that precludes development of a thermobaric round? And failing all of the above, are we left with only thermobaric aerial bombs (guided or dumb) to achieve the best result?

Back in the Cold War days, the west worked on munitions that killed through frag while the Soviets worked on munitions that killed through blast.
If you look at modern Russian munitions, they have many ways of putting thermobarics on a target.  And, the west is getting into it these days too.

 

[GnyHwy]

The main thing with thermobaric or fuel bomb is the volatility of the projectile itself.  It must be soft launched i.e. man portable rocket launcher or rocket artillery. 

It could not withstand the pressures of the inside of a gun (tank or arty barrel).

 

[McG]

I don't know about fuel-air bombs.  However, thermobaric should be fine for a gun launch- it is HE doped with an incendiary.

 

[AmmoTech90]

I don't know about fuel-air bombs.  However, thermobaric should be fine for a gun launch- it is HE doped with an incendiary.

Errr. Not quite.  It is an explosive that has a composition (normally more fuel, as in the fuel part of fuel/oxidizer mix) so that it produces a longer and usually higher pressure impulse.  Generally a larger fireball is the result, but this is incidental to the thermobaric effect.  It is not an incendiary as its purpose isn't to set things on fire.
Thermobaric weapons are more effective in some cases than straight HE, but it is just another tool in the box.  In some cases a thermobaric weapon would produce less damage than an fragmenting HE round.  Pressure drops off a hell of a lot faster than fragmentation so in an open field it would be less effective.

 

[cupper]

(Just as an aside, the jet of a HEAT round is moving at @ Mach 25, which is similar to the speed of a deorbiting projectile proposed in the THOR project. When you consider the damage a few ounces of metal moving at that speed can do, then scale it up to dozens or hundreds of kilograms [tactical THOR penetrators are supposed to be small, the size of broom handles, while the strategic ones that can penetrate missile silos and deep bunkers are indeed the size of telephone poles] the effects will be dramatic, to say the least).

I would dare say that the energy release upon impact would rival a small low yield nuke.

A show I watched recently about the Tunguska event in the early 1900's discussed several theories, one of which was a small asteroid perhaps several dozen meters in diameter which air burst with an equivalent energy release of 10 to 15 Megatons.

 

[BadEnoughDudeRescueRonny]

I would dare say that the energy release upon impact would rival a small low yield nuke.

A show I watched recently about the Tunguska event in the early 1900's discussed several theories, one of which was a small asteroid perhaps several dozen meters in diameter which air burst with an equivalent energy release of 10 to 15 Megatons.

I just read up on the Tunguska event on Wikipedia and some estimates go even as far as 30 megatons.



Also, I used an online kinetic energy calculator to estimate the kinetic energy of a 600 kg THOR rod traveling at 10,000 m/s (THOR researchers state that the projectiles would be traveling at a rate of at least 9000 m/s).
Here was the result (in joules):

30 000 000 000 joules (or 30 gigajoules) of energy  (by comparison a 120 mm APFSDS-T exerts about 13 000 000 j.)

I did another conversion and this was equivalent to far less than a kiloton in explosive yield! I was puzzled about this at first and then I realized that none of these conversions take into consideration the sheer damage and shock waves exerted by something with that much potential kinetic energy hitting the ground or a target since energy is dissipated upon impact. However, about 4 gigajoules has the same explosive energy as a ton of TNT. So a 600 kg THOR rod would have the explosive power of 4.5 tons of TNT PLUS an insane amount of kinetic energy.


But then I thought some more, the 30 gigajoules of energy is only about 2300 times more powerful than a 120 mm sabot projectile, which doesn't make sense considering the higher mass and velocity of the THOR projectile, not to mention the thermal energy generated by its re-entry into the atmosphere. My only guess is that increases in kinetic energy are exponential and not linear and that the thermal energy of re-entry are the factors that would contribute to THOR's conceptual destructive capabilities.

EDIT: I did some more research and found out that increases in kinetic energy are quadratic (x^2), not exponential and certainly not linear as I had originally guessed. This means that a 600 kg THOR rod would be 5 290 000 times more powerful than a 120 mm sabot round

Just my guess .

 

[lethalLemon]

All of this math and talk of projectiles and explosives and tanks is making me giddy like a school girl at a Backstreet Boys Justin Bieber concert.

EDIT to add:

EDIT: I did some more research and found out that increases in kinetic energy are quadratic (x^2), not exponential and certainly not linear as I had originally guessed. This means that a 600 kg THOR rod would be 5 290 000 times more powerful than a 120 mm sabot round

Why, why must you do this to me? Physics alone gets me all worked up, then you toss in explosions and military use... I'd kiss ya, if that was my kind of thing :rofl:

Anyway, the only problem with orbital kinetic weaponry is atmospheric reentry. Like Space Shuttles and those lander/return pods from rockets, the weapon and its targeting system will be subject to Planar/Debye (Plasma) Sheath. This presents a huge problem if they want to guide the weapon/munition even after it's been launched (like radio/video guided missiles and bombs), they targeting system will go blind. You have ions slamming against it at such insane velocities, electrons being reflected - trying to transfer from plasma state to solid state, it creates and an electrostatic field A.K.A. electrostatic shielding (basically acts as a localized EMP). So from Satellite to atmosphere, you know what your target is, where it is, and you are confident that the munition will strike. From atmosphere to target, you can hope that you hit your target. This would be especially frustrating for firing at moving targets - it moves, the munition will just kill a whole lot of evil rock/sand/water. There's also the risk that the munition will melt before it even reaches the target - so unless you build each sabot out of the materials that shuttles/satellites/pods are made out of (or something less expensive but will do the job, because you don't want to bankrupt the nation after one use), then your attempts are futile.

 

[AmmoTech90]

I did another conversion and this was equivalent to far less than a kiloton in explosive yield! I was puzzled about this at first and then I realized that none of these conversions take into consideration the sheer damage and shock waves exerted by something with that much potential kinetic energy hitting the ground or a target since energy is dissipated upon impact. However, about 4 gigajoules has the same explosive energy as a ton of TNT. So a 600 kg THOR rod would have the explosive power of 4.5 tons of TNT PLUS an insane amount of kinetic energy.

Unless an item has an energetic filling the only energy you have to worry about is kinetic.  I think you should re-exmine your math.  The factor that increases exponentially is the velocity.

 

[a_majoor]

The formula is KE=1/2MV^2

Specific calculations about THOR depend on other factors like the angle of approach and if the penetrator is stabilized at some arbitrary velocity before impact, but in general the entire effect of THOR is the energy of impact, there is no warhead or explosive payload.

I recall the tactical THOR was supposed to have a nose cap of the same protective material used on the Space Shuttle, which would eject and expose the sensor after re-entry. Small pop out tabs at the rear would guide the penetrator to the target. For the most part, THOR was designed to be targetted at either fixed targets (a shower of small ones over an airfield or harbour, big ones at bunkers and missile silos) or slow moving ones like ships at sea. If the technology had been developed in the 1980's as planned, it may have been refined to the point a troop on the ground could attack a hard point by calling down a THOR today, but given the cost and factors like how big the constellation in orbit was (which defines how many THORs are in orbit and how long it takes for a satellite to come overhead), THOR would be a strategic/operational weapon rather than a tactical one.

For anyone who can work the math backwards, Jerry Pournelle once wrote that a single THOR projectile (broom handle sized) would hit with the energy of 250 kg of TNT, which should define the size and velocity...

 

[lethalLemon]

The formula is KE=1/2MV^2

Specific calculations about THOR depend on other factors like the angle of approach and if the penetrator is stabilized at some arbitrary velocity before impact, but in general the entire effect of THOR is the energy of impact, there is no warhead or explosive payload.

I recall the tactical THOR was supposed to have a nose cap of the same protective material used on the Space Shuttle, which would eject and expose the sensor after re-entry. Small pop out tabs at the rear would guide the penetrator to the target. For the most part, THOR was designed to be targetted at either fixed targets (a shower of small ones over an airfield or harbour, big ones at bunkers and missile silos) or slow moving ones like ships at sea. If the technology had been developed in the 1980's as planned, it may have been refined to the point a troop on the ground could attack a hard point by calling down a THOR today, but given the cost and factors like how big the constellation in orbit was (which defines how many THORs are in orbit and how long it takes for a satellite to come overhead), THOR would be a strategic/operational weapon rather than a tactical one.

For anyone who can work the math backwards, Jerry Pournelle once wrote that a single THOR projectile (broom handle sized) would hit with the energy of 250 kg of TNT, which should define the size and velocity...

Such amazing stuff, I love it.

 

[Retired AF Guy]

Just something I put together. The source material is from 1982, so some of it may out of date. Enjoy. Any typos or formating mistakes are mine.

 

[McG]

The direct comparison of kinetic energy, chemical energy and nuclear energy is misleading.  These do not have the same terminal effects (heck, even within each energy category, engineers can design different terminal effects) and the energies are dissipated into the target & surrounding area differently.

Even assuming all KE was dumped into the target (no element of the penetrator remained having passed though to bury deeper in the ground or ocean), the direct comparison of energy does not work.  While I have no doubt the THOR concept could sink a warship, destroy an in-ground missile silo, or obliterate a skyscraper - there is no direct mathematical comparison to a nuclear weapon or mass of HE. 

 

[AmmoTech90]

The direct comparison of kinetic energy, chemical energy and nuclear energy is misleading.  These do not have the same terminal effects (heck, even within each energy category, engineers can design different terminal effects) and the energies are dissipated into the target & surrounding area differently.

Even assuming all KE was dumped into the target (no element of the penetrator remained having passed though to bury deeper in the ground or ocean), the direct comparison of energy does not work.  While I have no doubt the THOR concept could sink a warship, destroy an in-ground missile silo, or obliterate a skyscraper - there is no direct mathematical comparison to a nuclear weapon or mass of HE.

Agreed, quoting things like joules in no way gives an accurate picture of the terminal effects.  The terminal effects are going to be very different if the munition hits a peat bog, sand dune, or skyscraper.

And just because a factor in an equation is squared does not mean it is a quadratic equation.

 

[GnyHwy]

THOR would be a strategic/operational weapon rather than a tactical one.

I have no doubt about this.  We would need to come up with a new classification of target.  SDHVT (super-duper high value target).

 

[cupper]

And just because a factor in an equation is squared does not mean it is a quadratic equation.

Actually it does. Just that the coefficients of the X1 term = 0, and the constant = 0.