# The great conversion of MegaTraveller starships back to High Guard

No, it's supposed to be a power to weight ratio, like all other actual physical systems. MT Agility is a power to weight ratio. HG doesn't "use" weight, but if you amazingly use the D-ton mass assumption I used you miraculous get the MT formula from the HG formula. Clearly a freak accident. /end sarcasm.

More seriously, Striker uses a power to weight ratio (which MT also uses), to determine the velocity of vehicles. Higher power to weight = more velocity, NOT just power. Also, I never mentioned the M-drive. Both HG and MT use excess power not powering something else to determine Agility.
No, it's not just a power-to-weight issue. In HG it's a power to the M-drive issue.

Power means nothing without the "drive" to turn it into thrust. How quick is a dragster with bicycle wheels?

The problem, as simply as I can put it, is: 1 HG power plant unit = 1 MT power plant unit (EPs only) + "free" power for all the drives once the PP is "large enough".
No, there is no free power to the drives in HG.

When you use the jump drive it consumes a lot of power that is not available to any other system:
Jumping: A ship which breaks off by jumping must have a destination and enough fuel to get there. It must expend energy points equal to two turns output from a power plant whose number is equal to the jump being attempted (EP required =0.01MJn). If it can do this in two turns, it jumps at the end of two turns. If it can do this in one turn or less, it jumps at the end of one turn (in the pursuit step). A ship which cannot summon the required energy in two turns may not jump at all. For instance, if a ship with power plant 8 attempts jump 5, it takes two turns; if it attempts jump 4 (or less), it takes only one turn. Energy used to power the jump may not be used for other purposes.

The M-drive consumes power:
Energy points are used for four purposes: powering weapons, shields, for maneuver drives (for agility), and for computers.

Agility: Energy points remaining after weapons, screens, and computers have been installed may be applied toward the ship's agility rating. Divide the remaining energy points by 0.01M; the result is the number of agility points the ship has. Drop all fractional points. Agility is the ability of a ship to make violent maneuvers and take evasive action while engaging hostile targets. A ship's agility rating may never exceed its maneuver drive rating.
Agility is acceleration and can never be higher than max drive acceleration, no matter how much power we waste.

Example: The humble Scout is 100 Dt with a PP-2 (2 EP), MD-2, and JD-2.
While jumping the entire PP is devoted to feeding the JD for two turns, and nothing else can be powered, so no acceleration and no weapons fired.
If we mount a laser (1 EP), it has 1 EP left for the MD, so Agility-1 = 1 G acceleration, just as if it had a PP-1 (1 EP) and no laser.

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MT Agility is a power to weight ratio.
Yes, it is, without any drive to turn the power into thrust. And that is the ridiculous thing...

Why would we ever use an MD larger than 1, if we can accelerate at 6 G (Agility-6) just by wasting power?

Yes, it is, without any drive to turn the power into thrust. And that is the ridiculous thing...

Why would we ever use an MD larger than 1, if we can accelerate at 6 G (Agility-6) just by wasting power?
Because you can't do that. Agility is limited to the MD number. So Agility is indeed a function of MD, but only in the amount of excess power you can deliver. Once that is chosen, it's power to weight.

Except it isn't.
1000kg of liquid hydrogen fuel occupies 14 cubic metres.

So for deck plans 1.08 x jump fuel "displacement tonnage"

We could say that the liquid hydrogen is more of a [slush] than actual liquid liquid.
I think it's a reasonable enough compromise.

I mean, strictly speaking it contradicts the "liquid" bit, but it allows us to preserve the institutionalised 13.5 m³ (with some spare volume for tankage, even!) and is close enough that I think no one would really mind.

In my opinion, Not a lot of point arguing about whether two old versions of Traveller did it 'right' - but there is a point here (sort of): Marc might say he is bound by canon, but it would be more correct to say 'guided by canon', you can't be bound by contradictory rules. And that's what this conversation seems to have become.

(Me, I just want to be un-bound by the Virus* and Empress Wave† - but the best way non-contradictory to do that is to set a campaign in the era prior to Strephon's assassination, an event that didn't bind Loren Wiseman at all...)

*On a personal note, as much as I found the Virus annoying, and unnecessary for the eventual start of a new age of decaying splinter states, the thing about TNE that annoyed me the most was the 70ish year timeframe between the start of the Virus and the rise of the Space Vikings. Way too short. Most of the system names changed, lots of knowledge was forgotten, but that's less of a time than from today back to World War II, when my still living parents were alive (and have vague memories of the occupation - they were born a month before the Nazis invaded Norway) and my grandfathers' families fought in the resistance - I grew up with a bunch of those stories, some even verifiably true.

†And Empress Wave, I still think the 1 parsec per year thing was just an editing oversight, but the wave rolls on so it hits when it hits. At least to will be gone faster that way. Now there is an event where 70ish years could result in enough brain scramble and widespread damage where memories of the 'Before Times' where garbled.
Funny thing about Marc and canon is that T5 changes canon, as does MGT. As I see it they are a bit "flexible" in this area.

The collapse period is an interesting point. We know advanced societies can collapse faster due to technology being so interlocked in order to do something. In the future there probably aren't lots of books or hardcopy data since it's far too easy and convenient to put it on electronics. I think a bigger question would be related to how fast the tech chain would collapse, rendering all that knowledge lost on a device or storage device.

Never really paid much attention to Empress Wave. Psionics and teleportation in a game that is at least somewhat science based is already a stretch of the definition (but it's a game, and the Force was popular back then). Making a distortion field emanting from the core seems to layer more unnecessary gobbledygook on top of a concept really not necessary for the game. And none of the information really makes sense. A the rate it's travelling (1 parsec/year approximately) it would take about 8,000 years to travel from the core to the Sol system. The overall timelines don't seem to match the game universe timelines.

The power-to-mass ratio's for the higher TL armor seems to raise more questions than answers to me. Super-dense armor would have to be plated on something to strong enough to enable construction and support it's mass and structure. And that alone is incredibly dense and massive - far more than Lhyd.

Maybe a physics math gearhead can calculate the thickness of bonded superdense armor and just how thick it could be to be theoretically used as hull armor?

The power-to-mass ratio's for the higher TL armor seems to raise more questions than answers to me. Super-dense armor would have to be plated on something to strong enough to enable construction and support it's mass and structure. And that alone is incredibly dense and massive - far more than Lhyd.

Maybe a physics math gearhead can calculate the thickness of bonded superdense armor and just how thick it could be to be theoretically used as hull armor?
This has already been done in Striker and MT. I mean, it's fiction, but values have been set. BSD armor is very dense (32 g/ml per my variant) but therefore allows a much thinner shell (x0.14 to mass per MT).

Maybe a physics math gearhead can calculate the thickness of bonded superdense armor and just how thick it could be to be theoretically used as hull armor?
It's trivial using the same formulae Striker:
HG armour 10 is MT armour 40 + 3 × 10 = 70.
Armour 70 is armour rating 453 (=453 cm of hard steel).
Bonded superdense is 14 times as tough as hard steel so 453/14 = 32.4 cm superdense armour.

Agility is limited to the MD number.
Is it? Can you provide a quote for that as I can't find any such limitation in MT?

Is it? Can you provide a quote for that as I can't find any such limitation in MT?
Not in MT (just max 6) but yes in HG (min of MD or PP number), and the point of this exercise was to try to adjust MT to be closer to HG. If we are going to bring MT closer to HG, we also need to accept the limitations allow with the perceived advantages of HG.

Can I just say I like the back and forth of this thread and it is always fun to discuss this stuff.

Another Dilbert has just made me accept that the 13.5 cubic metre displacement ton and the 14 cubic metre displacement ton are the same.

The difference is in the definition.

In most Traveller iterations a displacement ton is the volume of 1000kg of liquid hydrogen, 14

While in MT and T5 it is the displacement of 929kg of hydrogen.

Can I just say I like the back and forth of this thread and it is always fun to discuss this stuff.

Another Dilbert has just made me accept that the 13.5 cubic metre displacement ton and the 14 cubic metre displacement ton are the same.

The difference is in the definition.

In most Traveller iterations a displacement ton is the volume of 1000kg of liquid hydrogen, 14

While in MT and T5 it is the displacement of 929kg of hydrogen.
Yes! Particularly when the stakes are low, like in a fictional game, the discussion can be free wheeling.

I know I've brought it up before but have you taken a look at the ship design system in GT ISW?

It basically builds HG using FF&S simplified.

I know I've brought it up before but have you taken a look at the ship design system in GT ISW?

It basically builds HG using FF&S simplified.
I hadn't, but I just did. It's not compelling enough versus the MT exercise I've just conducted, which I think solves the same problems. It's a perfectly good system to use, but I'm trying to perfect MT.

To perfect MT you need surface area, configuration, and armour thickness to derive armour factor...

To perfect MT you need surface area, configuration, and armour thickness to derive armour factor...
Because I like you, I did some math (OK, I like math). For a first pass, I assumed a spherical hull which does not address your surface area point. But continuing, I first looked at my Type A models. I converted armor volume to thickness, backed out the TL 14 multiple, and came up with a hard steel thickness of 23.2, or Armor 36, versus the correct value of 40. I then looked at my SDB, and came up with a hard steel thickness of 283.5, or Armor 64, versus the correct value of 67. So...pretty close already! It looks like some small multiple to my volume calculation would get us close to the right value. These results suggest that multiple is somewhere around 1.35 to my hard steel thickness. I'd need more time to figure out why that difference exists.

ETA: Oh cool! I just noticed that the actual weight multiplier for a spherical hull is 0.8x. As both my examples have 1.0x config multipliers, we should adjust thickness by (1/0.8)^(1/3) = 1.08. So now Type A thickness is 25.0 or Armor 37, and SDB thickness is 306.2 or Armor 65. So now we are only off by about 20-30%. Not a bad approximation!

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This has already been done in Striker and MT. I mean, it's fiction, but values have been set. BSD armor is very dense (32 g/ml per my variant) but therefore allows a much thinner shell (x0.14 to mass per MT).
I think Traveller got the idea of superdense from Pipers Space Vikings. There it was called collapsium, and an inch thick piece of regular steel was coated with a single layer of neutrons. Not sure it was ever specified more that. In the books a sheet of 1 inch collapsium steel has the same effective armor value/capabilities as 16 inch steel plate. However we know superdense matter such as neutronium has an insanely large mass.

I suppose without stating the collapsed matter's nuclear state, it's all hand wavium.

Not in MT (just max 6) but yes in HG (min of MD or PP number), and the point of this exercise was to try to adjust MT to be closer to HG. If we are going to bring MT closer to HG, we also need to accept the limitations allow with the perceived advantages of HG.
Quite, so Agility has nothing to do with the M-drive in MT, and that's ridiculous...

If you want you a system closer to HG, how about handling power like in HG: Make powering the M-drive optional, and acceleration (Agility) the proportion of M-drive power provided, so if you have 50% power for the M-drive, you get an Agility that is 50% of the M-drive potential?

Example: A Scout requires 350 MW for the M-drive for 2 G. If you provide it 0 MW you get 0 G. If you provide it 175 MW, you get 1 G. If you provide it 350 MW, you get 2 G. Just like HG. Simple enough?

That way you can always retrofit a laser to a spacecraft, and if you don't have enough power for both the M-drive and the laser, the acceleration suffers a bit while you fire the laser. Just like in HG.

To put it in another way, make spacecraft more like grav vehicles, where acceleration is actual thrust / mass, in both CT and MT. That is presumably the intended reality behind all the simplifications.

To perfect MT you need surface area, configuration, and armour thickness to derive armour factor...

Hull weight mod is proportional to hull volume or hull surface area, depending on size. For small ships Weight = ³/₁₀×Hull + 10. For ships larger than 10 000 Dt the weight tapers off, more like proportional to surface area.

The armour mod (~armour thickness) is 5 × 2^((AV-18)/8) [for AV≥14], rounded to three significant numbers.
I.e. armour thickness is proportional to 2^AV, or AV ~ thickness.

Armour (=Hull) weight and price are modified separately by configuration and streamlining:

Hull mass is WeightMod(~Hull) × ArmourMod(~AV) × ConfigMod, so proportional to all the things you listed...

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