What photon torpedoes SHOULD have been...

[Patrick Degan]

The target would have to have a better acceleration than 3000kps in one second to evade the torpedo or be an inordinate distance away to evade the strike.

3000 kilometers isn't that much in terms of distance in space. Your weapon would be a good close range weapon, but at a certain point, you'd be lucky to hit anything with it unless they were right next to you, cosmically speaking.

You could get around that problem by making the warhead the final stage of a multi-stage missile. That also gets around the problem of the exhaust and the recoil of the antimatter powered terminal stage. The kinetic kill vehicle isn't very large, so a missile carrying it wouldn't have to be huge.

The problem is the larger your missile the less of them you can carry. This idea also brings back the very problems which a 100kg trashcan-sized photonic rocket seeks to eliminate as well as lessening the munitions load. You may as well employ standard photorps if you're going this route.

[RedImperator]

3000 kilometers isn't that much in terms of distance in space. Your weapon would be a good close range weapon, but at a certain point, you'd be lucky to hit anything with it unless they were right next to you, cosmically speaking.

You could get around that problem by making the warhead the final stage of a multi-stage missile. That also gets around the problem of the exhaust and the recoil of the antimatter powered terminal stage. The kinetic kill vehicle isn't very large, so a missile carrying it wouldn't have to be huge.

The problem is the larger your missile the less of them you can carry. This idea also brings back the very problems which a 100kg trashcan-sized photonic rocket seeks to eliminate as well as lessening the munitions load. You may as well employ standard photorps if you're going this route.

I was addressing the range problem. If you're not concerned about that, then there's no need to make them multi stage. Otherwise, yes, you'll have to make a tradeoff somewhere, either by reducing your loadout or increasing the size of your ship.

However, I don't see what problems they bring back. You're still getting a higher yield from less antimatter. You still have a much smaller amount of antimatter you have to keep stable in each torpedo; the boost phase doesn't have to be antimatter powered. You could use a fusion engine, since it's clear the Federation has experience with them. Hell, you could fit one inside the present photon torpedo casing and use that as the boost phase.

[Patrick Degan]

The problem is the larger your missile the less of them you can carry. This idea also brings back the very problems which a 100kg trashcan-sized photonic rocket seeks to eliminate as well as lessening the munitions load. You may as well employ standard photorps if you're going this route.

I was addressing the range problem. If you're not concerned about that, then there's no need to make them multi stage. Otherwise, yes, you'll have to make a tradeoff somewhere, either by reducing your loadout or increasing the size of your ship.

All weapons systems involve a calculus of tradeoffs, naturally. While theoretically the range of a simple slug impelled to hypervelocity is infinite (until it hits something), a missile which can hit a target four seconds away, flight-time, still makes for a respectable weapon with a reasonable chance of scoring a hit at short to medium ranges (out to 12,000 km), particularly if you fire whole salvos.

However, I don't see what problems they bring back. You're still getting a higher yield from less antimatter. You still have a much smaller amount of antimatter you have to keep stable in each torpedo; the boost phase doesn't have to be antimatter powered. You could use a fusion engine, since it's clear the Federation has experience with them. Hell, you could fit one inside the present photon torpedo casing and use that as the boost phase.

The "increased yield" you're getting with this design, of course, is pure kinetic impact-force. And as for the boost phase, the ship's own torpedo launcher can already perform this function. A first-stage booster is redundant.

[RedImperator]

Kinetic energy from the ship's launcher can't account all the momentum we see in photon torpedoes, since they can change direction without losing losing velocity (though strangely, we never see them accelerate). Unless they're using some subspace do-funny to change direction while keeping the momentum imparted by the launcher, which is possible since I don't recall seeing anything on a photorp casing that's obviously a thruster.

[Patrick Degan]

Kinetic energy from the ship's launcher can't account all the momentum we see in photon torpedoes, since they can change direction without losing velocity (though strangely, we never see them accelerate). Unless they're using some subspace do-funny to change direction while keeping the momentum imparted by the launcher, which is possible since I don't recall seeing anything on a photorp casing that's obviously a thruster.

Granted; though this discussion is regarding what photorps could be in a more logical conception as opposed to how they're actually depicted in the episodes. In other words, an idea far more grounded upon basic principles.

[Gil Hamilton]

And since we mostly see photorps being applied as mainly short-range weapons... what's your point, exactly? You're also forgetting it's other tactical application as an orbital bombardment weapon.

Isn't the point of this to build a practical space weapon out of StarTrek technology? If it is to be practical for space warfare, it has to be dangerous and accurate at further than a few thousand kilometers.

Further, if you are making it an orbital bombardment weapon, you definitely have to make it dangerous and accurate at further than a few thousand klicks. Besides, you can't airburst a city with a kinetic kill weapon.

Oh, on that I agree. It's how I'd design the photorp system on my starship in either application. The difference is one of material efficiency: 400-600 micrograms of antimatter to propel a 100kg slug to 3000kps which packs a 107kt punch on impact with a solid target or a forcefield v. 1g of antimatter for a 30kt warhead in addition to the fuel requirement for a larger torpedo which takes up more storage space aboard the ship.

But if you make your 100kg trashcan out of the containment equipment for that 1g of antimatter, it's better yet, plus it allows for the opportunity for a proximity explosion or a "explosion at x distance from target" setting. Still get the kinetic kill aspect of that if it his shields, but it's backed by a nuclear sized explosion.

[RedImperator]

Kinetic energy from the ship's launcher can't account all the momentum we see in photon torpedoes, since they can change direction without losing velocity (though strangely, we never see them accelerate). Unless they're using some subspace do-funny to change direction while keeping the momentum imparted by the launcher, which is possible since I don't recall seeing anything on a photorp casing that's obviously a thruster.

Granted; though this discussion is regarding what photorps could be in a more logical conception as opposed to how they're actually depicted in the episodes. In other words, an idea far more grounded upon basic principles.

The one thing you are definitely losing in this design is the ability to maneuver in flight. It would probably be worthwhile, if you want to keep it simple, to abandon the current launcher design and replace it with something more flexible; multiple tubes at different angles, perhaps, or a turreted design, so that you don't have to turn the entire ship to aim. Or you could design the rocket nozzle to vector the thrust as needed. This would have the added advantage of allowing the engine to fire almost as soon as it left the tube, if it had to (you've just been jumped by decloaking Birds of Prey at ridiculously close range, for example), without blasting yourself with high energy gamma rays.

[Winston Blake]

if you could fuse one gram of matter and one gram of antimatter under conditions of 100% efficiency, you'd ideally get an energy yield equivalent to a 43 KT atomic bomb.

A 100kg object impacting a solid target (or presumably a deflector shield) at 3000 km/sec would produce a force equivalent to a 107kt nuclear blast, which is about equivalent to the W-76 warhead carried by a Trident II SLBM.

[snip]

A fuel load of 400-600 micrograms of M/AM would be sufficient for this type of torpedo, constituting a far more logical usage for antimatter than in a warhead.

Does anyone else see a problem here? To get 107kt of energy out, you'd need to put 5g worth of energy in (100% efficiency), rather than micrograms. How did you work out that 600 µg would be enough to accelerate it to 3000 kps?

[Patrick Degan]

And since we mostly see photorps being applied as mainly short-range weapons... what's your point, exactly? You're also forgetting it's other tactical application as an orbital bombardment weapon.

Isn't the point of this to build a practical space weapon out of StarTrek technology? If it is to be practical for space warfare, it has to be dangerous and accurate at further than a few thousand kilometers.

Except phasers are the long range weapon; those will reach a target far faster than any missile could. Remember that photorps were the secondary weapon for a starship.

Further, if you are making it an orbital bombardment weapon, you definitely have to make it dangerous and accurate at further than a few thousand klicks. Besides, you can't airburst a city with a kinetic kill weapon.

You're forgetting about bow-shock effects

if you make your 100kg trashcan out of the containment equipment for that 1g of antimatter, it's better yet, plus it allows for the opportunity for a proximity explosion or a "explosion at x distance from target" setting. Still get the kinetic kill aspect of that if it his shields, but it's backed by a nuclear sized explosion.

The idea is that the torpedo's fuel is expended in acceleration, and an additional nuclear explosion atop the impact force is redundant.

Does anyone else see a problem here? To get 107kt of energy out, you'd need to put 5g worth of energy in (100% efficiency), rather than micrograms. How did you work out that 600 µg would be enough to accelerate it to 3000 kps?

An admittedly very crude calculation on my part. If a more accurate figure can be presented, however, I am perfectly willing to concede the point.

[Darth Wong]

The problem with kinetic-kill weapons in atmosphere is that you waste a lot of your energy just trying to burn through the atmosphere. If the projectile is not massive enough, it won't even make it to the surface at all.

[Patrick Degan]

The problem with kinetic-kill weapons in atmosphere is that you waste a lot of your energy just trying to burn through the atmosphere. If the projectile is not massive enough, it won't even make it to the surface at all.

Not even at the velocities discussed? I'll admit that if so, then the idea is unworkable.

[Kuroneko]

Does anyone else see a problem here? To get 107kt of energy out, you'd need to put 5g worth of energy in (100% efficiency), rather than micrograms. How did you work out that 600 µg would be enough to accelerate it to 3000 kps?

Mr. Degan is not quite correct. Two grams are indeed 43KT equivalent under perfect efficiency, but a 100kg object at 3000km/s has a kinetic energy of 4.5e14J, or in terms of mass (100kg)(γ-1) = 5.0g, exactly as you've predicted. One can't suddenly get more energy than the work done on the projectile.

Not even at the velocities discussed? I'll admit that if so, then the idea is unworkable.

Especially at such velocities. At 3000km/s, there is no material strong enough to withstand the frictional forces involved. The projectile will fragment, which will only make it even easier for the atmosphere to absorb its kinetic energy. Of course, the timeframe of all of this is small enough to make it look like an instantaneous explosion. Think about it--at this velocity, the projectile would attempt to displace about 300-350kg of atmosphere, assuming Earth-like atmosphere near sea level, per each cm² of cross-section. At an altitude of ~50km, it's 1/1000th of that value, but it's still far from feasible.

[Patrick Degan]

Hmm... In light of the above mentioned objections, it appears my idea is indeed unworkable.

[Howedar]

Just to do a little piling on, you can't really equate the mass-equivilance of the antimatter with the kinetic energy of the missile. Rocket engines in general suffer from poor efficiency, basically because you need to go A/M->momentum->missile KE. Effectively turning your seemingly boundless energy/power into correspondingly large amounts of momentum is the bugaboo of rocket design.

[Patrick Degan]

The idea fails.

[Howedar]

Not necessarily - a KE kill vehicle is fundamentally reasonable. It's just not so much a slam dunk as you thought.

[Sikon]

While the opening post example is no longer being proposed anyway, it is interesting to observe how Star Trek technology being capable of its acceleration levels depends very much upon mass lightening.

For example, sublight performance of Federation ships includes being able to accelerate quickly and easily to 25% of lightspeed, even while not consuming much fuel. Yet, if not for mass-lightening, the ship going 0.25c would have kinetic energy equivalent to 690 million megatons for each million metric tons of mass. In the same proportion, the ship would also otherwise have (1 / X) * 2900 trillion gigawatts of engine power performance, where X is the limited number of seconds of acceleration it takes to reach 0.25c. In ST vs. SW discussions, Star Trek firepower and technological capabilities have been determined to be many orders of magnitude less than the preceding. Apparently their mass lightening avoids almost all of the kinetic energy ordinarily involved. [1]

Let's use the original kinetic torpedo example for an illustration of the potential value of mass-lightening reducing required kinetic energy. That kinetic torpedo was to have no mass-lightening apparently, as that is how it would have 107 kilotons of energy. Without mass-lightening, to accelerate to 3000 km/s in one second, the torpedo must have an engine with 300,000 g's of thrust. A lower limit on its required power with 100-kg mass is 450,000 gigawatts, and that is a lower limit not considering inefficiencies. As far as I know, there is not reason to think even Star Trek technology allows engine performance remotely close to 4.5+ million gigawatts per ton. [2]

High-energy fuel does not automatically solve the problem at all.

An analogy: In the real-world, a nuclear bomb massing under a ton can release millions of gigajoules of energy, equivalent to millions of gigawatts if averaged over a second for comparison rather than the actual sub-microsecond detonation time period. Yet real-world proposals for future nuclear rocket engines have been limited to performance of a few gigawatts or less per ton because of limits on what an engine can be designed to handle. Even the Orion nuke-pulse proposal was limited in the rate of increase of the vessel's kinetic energy after inefficiencies (with the limits of Orion corresponding to what Howedar implied several posts ago).

Considering Star Trek ship capabilities for high sublight speeds, mass-lightening does seem to help a lot.

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Torpedoes with relatively small, efficient nuclear warheads might be possible since Star Trek technology should allow extreme implosion better than the relatively bulky chemical explosives of today that are limited to a few thousand joules per gram. Theoretical nuclear yield relative to volume is up to hundreds of megatons per cubic meter, like up to hundreds of kilotons per liter, although that is before inefficiencies and other factors that could substantially reduce the total warhead yield to size ratio. (A liter is used as a convenient measure of volume even though no liquid is involved here). To illustrate how storage space wouldn't be much of an issue, the Galaxy class starship is 6.5 million cubic meters volume, although a new design would be best. [3]

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[1] Ship KE at 0.25c without mass-lightening: Energy = 0.5 * M * V^2 = 0.5 * (1E6 metric tons) * (0.25c)^2 = 0.5 * (1E9 kg) * (7.5E7 m/s)^2 = 2.8E24 J ... except that was without considering relativity, which has some effect even at just 0.25c, and actually KE is instead 2.9E24 J. That is 2900 trillion gigajoules. That is 690 million megatons. This is for each million metric tons of ship mass. Power required is (1/X) * 2900 trillion gigawatts, where X is the limited number of seconds of acceleration to reach 25% lightspeed. So Star Trek ships going at high sublight speeds must actually prevent very close to 100% of the preceding extreme energy requirements by having many orders of magnitude of mass-lightening.

[2] Torpedo engine power: Lower-limit neglecting all inefficiencies: Kinetic energy = 0.5 * (100 kg) * (3E3 km/s)^2 = 0.5 * (100 kg) * (3E6 m/s)^2 = 4.5E14 J. That energy is 107 kilotons since a kiloton is 4.2E12 J. Power = Energy / Time = (4.5E14 J) / (1 sec) = 450,000 gigawatts. Assuming the 100-kg mass of the torpedo on impact is its engine mass after expending propellant, the power-to-mass ratio is at least 4.5 million GW per metric ton.

[3] Though fusion or a combination would be an alternative for nukes, here is a sample illustration for plutonium fission, with some data from the excellent Nuclear Weapons FAQ website: Ordinary plutonium density is 19.8 g/cm^3. Ideal energy content is 17.3 kilotons/kg. Energy content of a 1 liter volume of plutonium = (1 liter) * (19.8 g/cm^3) * (1000 cm^3/liter) * (17.3 kilotons/kg) / (1000 g/kg) = 340 kilotons, before inefficiencies.

[Beowulf]

Not to mention, you're accelerating the missile at 300,000Gs, which is probably enough to make everything inside the missile flow like water around your engine.

[Bookkeeper-At-Arms]

Okay here's a nifty bit of retcon and technobabble I thought of to explain how they get decent efficiency out of the M/AM warhead. I intend to use the explanation in future fanfics, as well.

Photon Torpedo Mk. ! -- TOS era. This is actually an outgrowth of transporter technology. An antimatter containment vessel (ACV) has it's own transporter-effect module which, when triggered by a power surge from the launcher, begins a form of 'stationary transport', in effect making the ACV act like a giant photon (hence the term "photon torpedo"). Thus, the torpedo zips forward as lightspeed without need for a propulsion unit. When it hits something (like an enemy), the transporter effect collapses and the ACV rematerializes. However, the transport effect has no control mechanism or annular confinement beam or pattern buffer, so the ACV emerges as a homogonized lump of materials with the atoms of antimatter evenly distributed throughout the mass.[i] This provides at least 50% efficiency in the blast. Problems - zero maneuverability, limited range before the unstable transport effect makes it dissipate harmlessly.

Photon Torpedo Mk. II -- Now the ACV has a single-use warp engine attached. The launch activates the torpedo's warp drive, and it navigates itself to the target. Then the transport effect kicks in for a brief instant, homogonizing the matter and antimatter material and detonating. More efficient transport homogonizing allows smaller particles to interact in the blast, increasing the efficiency. Now it can have sensors and guidance systems installed.

Quantum Torpedo -- Exactly like Photon Mk. II, except the transport effect now homogonizes material down to the level of quarks. And the torpedo can be programmed for the desired level of efficency. Maximum efficiency is now probably around 90%.

Not a final answer, but it sounds good. Which is all we need from technobabble.[/i]

[Batman]

Okay here's a nifty bit of retcon and technobabble I thought of to explain how they get decent efficiency out of the M/AM warhead. I intend to use the explanation in future fanfics, as well.
Photon Torpedo Mk. ! -- TOS era. This is actually an outgrowth of transporter technology. An antimatter containment vessel (ACV) has it's own transporter-effect module which, when triggered by a power surge from the launcher, begins a form of 'stationary transport', in effect making the ACV act like a giant photon (hence the term "photon torpedo").

Despite the fact that transporters were never explained that way.

Thus, the torpedo zips forward as lightspeed without need for a propulsion unit.

Why? How do you make the torpedo go the direction you want it to?

When it hits something (like an enemy), the transporter effect collapses

Again, why? Transporters beam through matter practically every time we see them used. Why should this transporter effect of yours collapse on the first contact with anything when the Real Deal doesn't?

and the ACV rematerializes. However, the transport effect has no control mechanism or annular confinement beam or pattern buffer, so the ACV emerges as a homogonized lump of materials with the atoms of antimatter evenly distributed throughout the mass. This provides at least 50% efficiency in the blast.

No it doesn't. Not only would the be no 50% efficiency even if it did, there's no reason to assume an even distribution of the antimatter as, by your own words, the transport effect has no control mechanism. IF there WAS an even distribution of antimatter before transport the whole thing would have gone kablooey before transport ever happened. If there wasn't, guess what-there isn't going to be AFTER.

Photon Torpedo Mk. II -- Now the ACV has a single-use warp engine attached. The launch activates the torpedo's warp drive, and it navigates itself to the target.

So I take it it's no longer turned into photons, then?

More efficient transport homogonizing allows smaller particles to interact in the blast, increasing the efficiency.

The term NO comes to mind. Where M/AM anihilation is concerned it doesn't get smaller than protons/electron/neutrons which, guess what, are at the heart of M/AM interactions.

Now it can have sensors and guidance systems installed.

Which aren't going to achieve dick if it's still photonic.

Quantum Torpedo -- Exactly like Photon Mk. II, except the transport effect now homogonizes material down to the level of quarks. And the torpedo can be programmed for the desired level of efficency. Maximum efficiency is now probably around 90%.

Because you say so.