SB.com ENT photon torpedo thread

[Jedi Master Spock]

I felt a need to respond to this, but not enough of one to actually register and post at SB.com, so pass this on if you like. Not to say the thread was off-base - I like it - but as I read it, I couldn't help but fill in a few holes for my own sake in order to make use of the episode in question myself.

I don't know how much it helps, but when the shuttle was first nearing the Klingon ship (before it had descended a lot further into the atmosphere), the pressure was 15,000 GSC. I assume that means 15,000 grams per square centimeter. That would work out to 213.29 pounds per square inch, for whatever that's worth.

That would be 14 bar, which we would expect at a reasonable depth in a Jovian atmosphere. This is actually very useful information, as it allows us to factor in drag fairly accurately.

More critical than the 500 meter photon torpedo, however, is the earlier, less effective torpedo, for which we have better numbers:

What was that?
Weapons fire.
Where?
Bearing 297 mark, 261,
down about two kilometers.
REED:
Did it work?
We've moved up,
but only 200 meters.

More precise figures:
Raptor: 145m length (EAS), 115m wingspan. 6413 sq m area from beneath (GIMP). I would put mass at 100,000-200,000 metric tons myself, giving a gravitational potential increase of 6 +/-2 x 10^11 joules (x 20 m/s/s, x 200 m) and an initial velocity of 89 m/s. Assuming that the Raptor absorbed 100% of the blast energy passing through, and noting
this is 1/7838th the area of a 2 km radius blast, we get total blast energy of 4.7 +/- 2.4 x 10^15 joules. Blast energy is usually around half the total yield.

This is neglecting air resistance. Doing a quick numeric integration with a spreadsheet, using 14 bars of atmospheric pressure and noting that the Raptor is nearly completely unaerodynamic in that position, I get an actual initial velocity of around 94 m/s (with a flight-to-peak time of around 6 seconds), meaning 12% more energy.

A reasonable off-the-cuff estimate would then be 2.5 +/- 0.8 megatons for the yield. This is still significantly low, however, unless previously unmentioned technobabble allow the Raptor to fly with 100% of the blast energy impacting it. I'll go into details on exactly how much we can expect to be transmitted another day, however, since I've spent long enough already writing this.

As a quick consistency check, the Raptor should absorb 16x as much energy and therefore fly 4x the initial speed, which is in the right neighborhood for a 22 second flight from the closer photon torpedo.

[Mike DiCenso]

That actually helps us get good potential figures for the later Earth Starfleet photonic torpedoes, as well as get a decent handle on shield ratings for this era.

For that I would look to the season 2 finale "The Expanse", where we learn that a 22nd century BoP chasing the NX-01 could withstand several photonic torpedo hits by transfering nearly all the aft shielding power to reinforce the existing foward shields.

This would imply at least several megatons shield rating for a modest sized
warship of that era, assuming that at least 4 2.5 MT torpedoes were fired, and up to half the explosive energies were released into the target vessel's shields.
-Mike

[l33telboi]

I felt a need to respond to this, but not enough of one to actually register and post at SB.com, so pass this on if you like. Not to say the thread was off-base - I like it

Of course you did. Who can resist loving my threads?

In any case, i watched the episode the following day and noticed that the 500 thingy mentioned 6 warheads, not just the one. So even that highly simplistic figure was way off.

[Mike DiCenso]

If you're uncertain about what happened in an episode's dialog, but cannot watch it for whatever reason, there are good online resources, such Chakoteya.net, which has transcripts of the final as-aired dialog, rather than suspect scripts. Apparently Chakoteya will be starting on transcribing ST:TNG soon.
-Mike

[Mike DiCenso]

Here's some relevant dialog:

[Klingon Bridge]

(a photon torpedo has been fired down into the lower atmosphere)
HOSHI: One thousand metres. Two thousand. Three thousand. (detonation, the ship shakes) No effect! We're still sinking.
T'POL: The shock wave dissipated before it reached us.
REED: We'll need to detonate one closer next time. (the hull groans)
T'POL: The ship's hull is under enough pressure already. If you detonate a torpedo too close.
REED: And if I don't? We need to generate a large enough shock wave to push us into a higher orbit. To do that, the blast has to be big and it has to be close. (T'Pol nods) You heard the Sub-Commander. Load two this time.


The first torpedo is fired and dedonated at 3,000 meters distance, though the ship shakes noticably, it does not make it climb far enough upward.


[Shuttlepod]

ARCHER: (doing the flying) Sensor resolution's dropping off.
BU'KAH: This was your plan? To grope in the darkness and hope to stumble across my ship?
ARCHER: That's how we found it the first time.
BU'KAH: (shuttlepod jolts) What was that?
ARCHER: Weapons fire.
BU'KAH: Where?
ARCHER: Bearing two nine seven mark two six one, down about two kilometres.

[Klingon Bridge]

REED: Did it work?
HOSHI: We've moved up, but only two hundred metres.
REED: That's all?
HOSHI: (a big bang inside the ship) A compartment just collapsed. Deck three, green sector.
REED: This whole damn ship's coming apart. How many torpedoes do we have left?
HOSHI: Six.
REED: Load two more.
HOSHI: It won't be enough.
REED: Load the weapons.
HOSHI: We already tried. It didn't work.
REED: Ensign.
T'POL: She's right. We'll never reach a safe altitude climbing a few hundred metres at a time.
REED: The longer we stand around arguing the more ground we lose.
HOSHI: Fire them all. What if we detonated all the torpedoes at once?
T'POL: We may gain enough altitude, but I doubt we'd make it in one piece.
HOSHI: I don't know about you but I'm willing to take the chance.
REED: We'll detonate at eight hundred metres.
HOSHI: I was thinking more like five hundred. Look, I didn't come all this way to get crushed in the atmosphere of some anonymous gas giant. Loading ports one through six.
REED: Brace yourselves.
HOSHI: Torpedoes armed. (as she presses the launch button, circuits explode on the bridge)

Here we get see the shuttlepod gets jolted, and the second torpedo raises the Raptor up only 200 meters. They then try a final time using all the remaining torpedoes at 500 meters. The exact result of this multi-torpedo firing is not made known, but it is enough to raise the altitude enough to leave the Raptor reasonablely safe.

Another note, the 15,000 GSC statement is made well before the first shuttlepod carrying Reed, Hoshi, and T'Pol docks with the Raptor. The ship was stated to be safe for an hour's time before it sank too deep in the gas giant's atmosphere and be crushed. So that is actually a lower limit to the air resistance numbers.
-Mike

[Cpl Kendall]

That actually helps us get good potential figures for the later Earth Starfleet photonic torpedoes, as well as get a decent handle on shield ratings for this era.

For that I would look to the season 2 finale "The Expanse", where we learn that a 22nd century BoP chasing the NX-01 could withstand several photonic torpedo hits by transfering nearly all the aft shielding power to reinforce the existing foward shields.

This would imply at least several megatons shield rating for a modest sized
warship of that era, assuming that at least 4 2.5 MT torpedoes were fired, and up to half the explosive energies were released into the target vessel's shields.
-Mike

So if I understand all this correctly the maximum yield of the NX-01's photonic torpedo is 2.5 MT?

[Mike DiCenso]

Um, no. If it were. it would only be a conservative calc, since we are comparing the much smaller Raptor's torpedo yeilds to the larger NX-01. The NX-01's photonic torpedoes being able to manage a maximum yeild high enough to put a 3 km wide crater in an asteroid, which in turn would likely require tens of megatons.
-Mike

[Cpl Kendall]

I was going to say that 2.5 MT is pretty shitty for any starfaring civilisation. Hell we managed a 60MT blast in the 60's with a nuclear device. And that was because the device was dialed down, the designed yield was 100MT. The 22nd century SF should be able to match or exceed that or why even bother using antimatter?

[Mike DiCenso]

Presumeably, even if the yeild was around 2-3 MT, one could assume that the warhead used is much lighter, and more compact than any nuclear weapon currently available for comparable sized, or larger yeild. The Tsar Bomba, which you refered to, was a model for a 100 MT device, most sources seem to generally agree the yeild was 50 MT:

http://en.wikipedia.org/wiki/Tsar_Bomba


A 50 MT yeild from a 27 metric ton device. By comparison, a photonic torpedo, is vastly smaller.
-Mike

[Jedi Master Spock]

So if I understand all this correctly the maximum yield of the NX-01's photonic torpedo is 2.5 MT?

Not quite. The actual (effective) yield of a Klingon photon torpedo is greater than 2.5 MT (see the last section) although that's a good place to start.

How much greater depends on the shockwave speed and whether it was reflected or absorbed by the ship's shields/SIF/hull.

[Mr. Oragahn]

Presumeably, even if the yeild was around 2-3 MT, one could assume that the warhead used is much lighter, and more compact than any nuclear weapon currently available for comparable sized, or larger yeild. The Tsar Bomba, which you refered to, was a model for a 100 MT device, most sources seem to generally agree the yeild was 50 MT:

http://en.wikipedia.org/wiki/Tsar_Bomba


A 50 MT yeild from a 27 metric ton device. By comparison, a photonic torpedo, is vastly smaller.
-Mike

I concur, the sheer size of the pair of warheads mounted inside torpedoes is extremely small.
The other advantage, as I agreed in a late debate, is that they can be charged to any yield, as far as a warhead accepts antimatter. It makes it a formidable tactical lightweight weapon of extremely variable yields.
Besides, it comes with plenty of stuff inside, notably its own shield generator and very good control systems.

What it lacks in sheer wank punch, it gains in precision and adaptation (is that a word?), which is just as godd, if not much better in terms of military strategy.

But, well, anyway, unless we're talking about fast particle beams, powerful lasers, or railguns/coilguns (or other forms of advanced slugthrowers), advanced missiles in SF is always a big yes to me.

Well, as far as more or less conceivable weapons are concerned. Of course if we start to deal with much more exotic weapons, which end being as good if not better...

[l33telboi]

The problem with comparisons like the Tsar Bomba vs. a Photon Torpedo is that the two things aren't similar, they aren't meant to do the same thing.

The Tsar Bomba for instance is the largest nuke ever created by mankind, it was so large in fact that people decided that its effectiveness would've been greatly reduced in a war, maybe even completely ineffective. Heck, they had to remove 50% of the fissionable material inside the bomb and outfit it with heavy-duty parachutes just so that the guy flying the plane would be able to get away in time.

The Photon Torpedo on the other hand is nothing but a standard ship-to-ship weapon.

So if you want to make a comparison, you should make it between the correct things. An Enterprise era torpedo is for example analogous to (oddly enough) a modern era torpedo. A modern torpedo has a warhead weight of almost 300kg (if I’ve understood things correctly, I’ve never been much of a military fanboy), which would mean an explosive energy of almost 0.4 tons of TNT (or 0.0004 kilotons if you understand that better) compared to the single digit megaton figure a ENT era torpedo would have.

On the other hand, if you want to compare something to the Tsar Bomba, it would have to be the single biggest boom the factions in Enterprise have been able to create. Sadly, for the humans, I don’t think we’ve never seen such a weapon.