Errata - that difficult subject

[E.D.Quibell]

I would advise not changing the "One Small Step" numbers. At least not without doing due diligence and research. If I recall they are aimed at realism. I think it is your build habits that need to change Ewan

But darn it Dan ... I'm an RPGer ... not a Rocket Scientist!

I want something reasonable, that works within the existing rules .... recalculating G outout due to loss of wiegh from fuel usage with minute durations and fuel tanks the size of super tankers just isn't that.

Best regards,

Ewan

 

[E.D.Quibell]

Don't change the One Small Step numbers just to improve performance.

I'd be happy with improved performance. It makes no odds if you reduce the fuel usage or increase the rocket performance it's pretty much the same in the end.

Overall, YES ... realistic reaction drives suck compared to magic Grav Drives.

PS. Real rocket scientists aim for 1.2 G (or higher) at liftoff and 4G max for people.

Thanks, at least 1.2 G gives me somthing to aim for! I might get all of 2 minuets performace!

Best regards,

Ewan

 

[E.D.Quibell]

The revised numbers are from an e-mail exchange between Charles Gannon and George W. Herbert in 1992, which George Herbert then posted to the TML. George was a real world rocket designer (as demonstrated in the "reviser's notes", which I've quoted below). I tracked him down in 2010 by finding his comments on some aerospace forums. Your mention though reminded me I was supposed to get back to him to see if he had more material, so I've just dropped an e-mail out.

Well thanks for letting me know. At least he's a real rocket scientist.

Perhaps some older COTI members might remember George W. Herbert from the TML? He apparently didn't stick around for TNE...

I have to say I don't remember, but then it was almost 20 years ago! You know I'd even forgotten that most people outside of academia didn't even have email back then, let alone dial up accounts from home, and they used to drop off the TML when they left University.

Best regards,

Ewan

 

[OjnoTheRed]

Ewan, one thought occurs to me: here's a link to specs for the Expendable Launch Vehicles - weights, fuel loads, dimensions. Assume a TL7 or TL8 and see how close you can get a design to these specs. I did something similar with the Holden SS Commodore here based on specs I found just using Google. I think this design came within the expected parameters for a six-cylinder large family car. Whichever rule set comes closest gives you an idea - I know that we're gamers rather than scientists but our beloved game of Traveller does reference the real world.

 

[atpollard]

Thanks, at least 1.2 G gives me somthing to aim for! I might get all of 2 minuets performace!

Another useful rule of thumb is 80-90% of the rocket will be fuel (Earth to LEO) with the other 10-20% being everything else.

Actually, look up fuel depots and a solar system delta-V chart and you will see that you can get pretty far with a reasonable gas tank, multiple short hops between gas stations and LOTS OF PATIENCE.

This should help get you started seeing the possibilities:

AffordableExplorationArchitecture2009

Another design option for orbit to orbit interplanetary travel is a constant low thrust rocket ... like 0.1G or 0.01G or 0.001G from Earth to Mars.
Ion engines get good fuel economy.

 

[Ishmael]

I feel that the listed volume for ship missiles is incorrect.
In both the original rules and the errata so far, the ".1" in the charts has been accepted to be ".1 cubic meters, or 100 liters", which I feel is too small.
".1 cubic meters" is slightly larger than an AIM-9 Sidewinder AAM, and slightly smaller than an AIM-7 Sparrow AAM.... 100 liters is roughly half the volume of a 55 gallon drum.

I propose that the unit of measure be changed to ".1 dtons" or 1.35 cubic meters, which is slightly smaller than a Tomahawk cruise missile. This seems more reasonable to me, given the ranges and warhead sizes that space missiles of the various tech levels ( from 7-15 ) are suppose to have.

This would also allow for better compatibility with Striker and FF&S1 design sequences for porting equipment designed in those rules more easily.

There should be no other changes concerning launcher volumes when designed by other sequences.

 

[aramis]

I'm not finding the AIM-9M thrust data in detail, however... the arming fail-safe on the warhead requires 20G's for 5s...

So we know it exceeds 100G/sec

We know it's peak performance is a 32G lateral turn; we can presume that is not initial launch, but we also know that this is not measured at terminal ...

And we know from video that it has at least 7 seconds tracking... It's safe to assume a median thrust of 30G and 15s thrust. That is roughly 450 G/sec... just shy of 1G/turn in CT.

Note also: the Mk 36 Rocket Motor is a 40kg solid rocket in an 85kg missile...

And it's about 85 KG, that AIM9-M at 287cm long, 13cm diameter, 64cm wingspan. 38L of missile, not counting a L of wing; cassette-box of roughly 50cm square and 3m for 0.75 cu meters of missile.

And that missile can utterly destroy an unarmored target (by a variety of means, not the least of which is causing the high subsonic or faster airframe to be ripped apart by airflow induced forces, and also by causing an engine rotor blade liberation). What people seldom realize is that an AIM9L can down an aircraft before the warhead even arms; An F15 fired an AIM9L at a target past his wingman; it impacted his wingman's tail, and ripped the tail fin off before attaining full speed; the damaged aircraft's engine also was disabled by the impact, but it was able to return to base, barely. (The MiG fled once it realized it was 1. in Alaskan Airspace, and 2. facing live missile fire, not just lock-tone....)

I've heard that the AIM9L has 32G for a full 20 second life. That's with about 40% mass in fuel... (and over 1 G-Turn of accel).

Larger missiles are not higher performance there; they are higher ratios of fuel to warhead... But the AIM9L hit warped the airframe of the F15 on a glancing impact... So a missile already 2.5x larger, and having roughly the same warhead, yeah, I buy it... because the warhead and guidance is now about 20% of the missile, or less.

But just what, given, say 1200G/sec, is the optimum thrust for distance? As slow as lets you hit the target. At 12G, that's 100 sec, and 1200km. The canon CT missile was 9000 G/Sec at 6G. It really is implied it's a kinetic, as it's vector difference adds to it's damage.

 

[DonM]

I feel that the listed volume for ship missiles is incorrect.
In both the original rules and the errata so far, the ".1" in the charts has been accepted to be ".1 cubic meters, or 100 liters", which I feel is too small.
".1 cubic meters" is slightly larger than an AIM-9 Sidewinder AAM, and slightly smaller than an AIM-7 Sparrow AAM.... 100 liters is roughly half the volume of a 55 gallon drum.

I propose that the unit of measure be changed to ".1 dtons" or 1.35 cubic meters, which is slightly smaller than a Tomahawk cruise missile. This seems more reasonable to me, given the ranges and warhead sizes that space missiles of the various tech levels ( from 7-15 ) are suppose to have.

This would also allow for better compatibility with Striker and FF&S1 design sequences for porting equipment designed in those rules more easily.

There should be no other changes concerning launcher volumes when designed by other sequences.

Can you give a specific page/paragraph/table you would like changed?

 

[Swiftbrook]

I feel that the listed volume for ship missiles is incorrect.
In both the original rules and the errata so far, the ".1" in the charts has been accepted to be ".1 cubic meters, or 100 liters", which I feel is too small.
".1 cubic meters" is slightly larger than an AIM-9 Sidewinder AAM, and slightly smaller than an AIM-7 Sparrow AAM.... 100 liters is roughly half the volume of a 55 gallon drum.

I propose that the unit of measure be changed to ".1 dtons" or 1.35 cubic meters, which is slightly smaller than a Tomahawk cruise missile. This seems more reasonable to me, given the ranges and warhead sizes that space missiles of the various tech levels ( from 7-15 ) are suppose to have.

This would also allow for better compatibility with Striker and FF&S1 design sequences for porting equipment designed in those rules more easily.

There should be no other changes concerning launcher volumes when designed by other sequences.

The ".1 cubic meters" in the chart is consistent for the MT rules. If you look further down on page 74 of the RM (1st printing), you see the line "A 100-ton bay used as an ammunition magazine can hold up to 13500 missiles." That 100-tons x 13.5 Kl / .1 per missile = 13,500 missiles. Also, modifying this rule changes the stats on every MT starship design that uses missiles, many of which are excellent DGP designs.

Looking into it another way, if you make the missiles bigger, do you want to increase their 'bang' as well?

If I were to include this, I would have it as an optional rule.

As a side note, IMTU 100-ton missile bays don't fire 100 missiles per round. They fire something like 10 ICBM's per round. A 50-ton bay fires 5 ICBM's per round. The bay's are big, for big weapons, not just a lot of little weapons. No, this isn't in the rules, it's just my thoughts.

Don, any ETA on the next version of the MT Errata? Thanks for all your effort!

-Swiftbrook

 

[far-trader]

The ".1 cubic meters" in the chart is consistent for the MT rules.

Consistency (in this case within one set of rules and contradictory to all? the others) does not equal correct.

Also, modifying this rule changes the stats on every MT starship design that uses missiles...

By reducing the missiles carried by 90% which is (or should be) pretty much moot.

...many of which (ships) are excellent DGP designs.

...many of which should not be overly impacted by the change of the number of missiles carried, I would think.

Looking into it another way, if you make the missiles bigger, do you want to increase their 'bang' as well?

Or, looking at it another way, did DGP decrease the 'bang' when they made them smaller? No, I don't think they did. Not significantly so iirc.

 

[Swiftbrook]

By reducing the missiles carried by 90% which is (or should be) pretty much moot.

I strongly disagree with you here. Reducing the missiles carried by 90% would drastically change the design and the game! From 100 missiles to 7 is a HUGE change.

At first, I just assume it was a typo and that you meant a 10% reduction or "reducing to 90% the missiles carried". Then I read the post again and Ishmael is suggesting reducing the missile capacity by 93%. As written, 1 dton holds 135 missiles. As proposed, 1 dton holds 10 missiles. A 92.6% decrease in capacity. A ship that currently has 14 battery-rounds of ammunition would be reduced to one round of combat! Two if you include the missile in the turret/bay. That's unacceptable.

-Swiftbrook

 

[E.D.Quibell]

You would also need to increase the cost of the missile to match the drop in number.

As stated in the rules to fill a 100 ton bay (a working shooting one) it costs:

MCr 2 Standard HE
MCr 15 Nuclear
MCr 20 Antimatter

makeing sure the price of the missiles matched the current price of reloads would make the costs:

Standard HE Cr 270,000
Nuclear MCr 2.025
Antimatter MCr 2.7

_each missile_

meaning the cost of a single Standard HE missile would be the same as an air-raft. Effectivly putting it out of reach of the average party of PCs, and making it far more cost effective to buy Beam Lasers.

I'd argue against the change.

Best regards,

Ewan

 

[E.D.Quibell]

In fact changing the size of the missiles just doesn't work on so meany levels.

You either decrease the effectivnes of missiles in general as a weapon, but reducing the number of battry rounds due to magazine volumes increaseing 13.5 times for the same combat effectivness.

Or you increase the cost of the missile and fire less of them, but then that means you couldn't have missile turrets because 1 new missile would be as combat effective as 13.5 old ones, and the PCs wouldn't be able to afford them anyway.

By changing the size of missiles you are fundermentally shifting the peramiters of the combat system away from them by making them less effective, and significanly increasing the combat efectivness of everything else.

Presumably you would also increase the size of sand canisters to match the size of the new missiles as well? meaning a significant drop in effectivness in defence.

Best regards,

Ewan

 

[McPerth]

I know some cascade skills are different for some races, mostly if they are skills used exclusively by that race (infighting or delclaw included in Mixted Combat, Scrounging include in Economics, etc); but in both, V&V and S&A, Tactics skill is included in Inborn, while nor in the PM nor (AFAIK) in the errata is it included. Is that intentional or should be fixed in errata?

 

[Ishmael]

In fact changing the size of the missiles just doesn't work on so meany levels.

After some research, I've found that MWM wrote a booklet that describes missiles almost exactly as Sidewinders right down to the 10Kg warhead. His nukes were obviously made in the mold of the W-54 nuclear trigger which was used in an atomic AAM version of the Hawk, as well as being the warhead on the Davy Crockett recoiless rifle...its yield ranged from .01Kton to .6Kton

The thing is, in non-High-Guard inspired rules, the penetration of the 10Kg HEAP warhead ranges from ~30, to ~45 which is no penetration of else a low pen result against a simple unarmored AV=40 ship. This doesn't jive well with the space combat damage tables ( imho) and explaining the difference by calling it a kinetic kill missile won't work after figuring missile performance using the info for appropriate thrusters. ( at 100 liters in vol., there aren't many choices that can even be used in the MT ruleset. ). 7 G-turns is about it ( from my few attempts ). and that's not nearly enough to get out to 'far' range where missiles get a +1dm. Which is odd given that such a range is 21 '25,000km' squares, which give a -21 dm to sensor tasks to locate and to get a lock-on (unless that's been changed and I didn't notice).

The nuke at least has a pen of around 97 at tech 15, based on demolition tables and 100 tonnes of explosives.
The difference in damage caused between the high-guard -type rules and the striker-based rules is a serious breach of rules' internal consistency imo.

You either decrease the effectivnes of missiles in general as a weapon, but reducing the number of battry rounds due to magazine volumes increaseing 13.5 times for the same combat effectivness.

Or you increase the cost of the missile and fire less of them, but then that means you couldn't have missile turrets because 1 new missile would be as combat effective as 13.5 old ones, and the PCs wouldn't be able to afford them anyway.

By changing the size of missiles you are fundermentally shifting the peramiters of the combat system away from them by making them less effective, and significanly increasing the combat efectivness of everything else.

Not less effective a weapon, so much as limiting the number of times it can be fired. I had thought that missiles should be a serious stand-off weapon, and not just something that is thrown at a target primarily to force it to allocate its own weapons to point defense, thus preventing them from firing at you. There is no way anyone can convince me that a glorified Sidewinder can be a ship killer.

Frankly, I feel that the parameters of the combat system in question are already seriously borked by the very nature of the method for determining the number of hardpoints, the effectiveness and role of sandcasters, and the high-guard carryover of computer dm's, which were an abstraction of the effectiveness of a ship's electronics and sensors; that dm should be a confrontation task between sensor and ECM ( with sandcasters being chaff/flares which become a defensive dm against a sensor lock attempt. But these things are well beyond the scope of errata, so I'll not expand upon those here.

Presumably you would also increase the size of sand canisters to match the size of the new missiles as well? meaning a significant drop in effectivness in defence.

keep them the same size if you like.
I feel that sandcasters as defensive 'shields' of a sort against incoming fire is simply wrong.
Once a 100 liter cannister disperses out when launched, it couldn't possible have any more effect on missiles/lasers/energy weapons than smoke. I'd use it like smoke dispensers on AFV's or smoke screens for Jutland in Spaaaace to disrupt weapons locks as a -1dm per battery_round fired.
But that's just me.

after a good deal of consideration, I've decided that the high-guard combat grafted into MT is not worth fixing and a new system based on a combination of mayday and MT's vehicle system with attention paid to ECM and EW is more attractive.

I withdraw my suggestion.


btw.... 1 G, or 10m/sec^2 for 20 minutes ( 1200 sec ) gives an addition to velocity of 12KM/sec. Drifting at this velocity for 20 minutes ( 1200 seconds ) will cause a change of position by 14,400 km, not 25,000 km. Perhaps MT's 'squares' in the space combat section should be changed to 15,000, or .05 light/seconds, from the present 25,000 km. just a thought

 

[McPerth]

After some research, I've found that MWM wrote a booklet that describes missiles almost exactly as Sidewinders right down to the 10Kg warhead. His nukes were obviously made in the mold of the W-54 nuclear trigger which was used in an atomic AAM version of the Hawk, as well as being the warhead on the Davy Crockett recoiless rifle...its yield ranged from .01Kton to .6Kton

In the Black Globe section of combat rules, it’s specified that nuclear missiles inflict 25000 Mw per factor. That means a TL 7-12 single missile inflicts 25000 Mw, and one TL 13-20 inflicts 50000 Mw.(*)

That puts the TL 7-12 missiles into the 20+ kton range, and those of TL 13-20 in the 40+ kton range. That’s quite a lot more than your Davy Crockett warheads (0.1-0.6 kton)

(*) As we're talking about energy and not power when talking about energy sinks in a BG or energy inflicted to them by weapons, I always assume they are Mw h (energy units) instead of Mw (power units). If that's not true, then all my calculations are void.

 

[Ishmael]

not my Davy Crockett warheads...MWM's.
a warhead in the kiloton range you're mentioning would not fit into a 100 liter missile and masses much more than 50 kg. ( based on Striker nuclear weapon sizes/masses... the weapons/warhead tables in MT are a direct copy from Striker, so Striker nukes should apply ).

In fact, that's one of the reasons I made the suggestion; its a glaring rules inconsistency.

 

[McPerth]

not my Davy Crockett warheads...MWM's.
a warhead in the kiloton range you're mentioning would not fit into a 100 liter missile and masses much more than 50 kg. ( based on Striker nuclear weapon sizes/masses... the weapons/warhead tables in MT are a direct copy from Striker, so Striker nukes should apply ).

In fact, that's one of the reasons I made the suggestion; its a glaring rules inconsistency.

You're probably right, I don't know enough about nukes to have a definite oppinion.

IIRC, in Ship's Operator Manual talks about the most modern nukes being laser tiggered fusion warheads. May be those devices could fit into those missiles...

But that arises another problem...

Those missiles, having no radioactive fision reaction to stop, should be immune to nuclear dampers, so nuclear missiles should have two cathergories, those tiggered by a fision device and those tiggered by laser devices, the first being affected by ND, while the seccond class probably requiring higher TL. I'm not sure wich class would be cheaper...

 

[McPerth]

I've recently found some old notes from when I refereed MT about more things that can be useful for errata:

- In most mustering out tables (both money and benefits, from PM, Solomani and Vargr CharGen) it should be specified that modifiers are not cumulative (unless they are, but I don't believe so). Aslan benefits table modifiers are cumulative, as they reach to 8.

- In Vargr, Solomani and Aslan mustering out benefits tables, jack-O-T give a +1 modifier, while in PM (imperial characters) doesn't. Is that intentional or an errata? If intentional, Solomani characters that use imperial tables (profesions whose tables are not changed, e.g. flyer) should apply it (as they apply it to their own tables)?

- Prospecting skill is impossible to obtain unless you choose belter profesion. IMO it should be included in Exploratory cascade skill.

 

[McPerth]

From CONSOLIDATED MEGATRAVELLER ERRATA, v2.19 (09/15/10), page 67

Page 64, Step 4, Hours in Jump Space (clarification and addition): The formula given for normal jumpspace
exit is: 124 hrs + (2D×6 hrs), yielding a result of from 136 - 196 hours (5.7 to 8.2 days). However, this does not account
for military operations when vessels know they have to arrive in unison. Such vessels spend significantly longer at the
start computing and sharing jump vector computations. This leads to a much more accurate jump exit at the other end,
with the error dropping significantly

If double the jump preparation time is spent with all the affected ships in computer link via communication lines,
use the following formula instead: 167 hrs + (2D×0.1 hr), yielding a result of from 167.2 - 168.2 hours. Most ships will
arrive within minutes of each other, with the worst spread being up to an hour apart. Constant communication during
the jump vector generate is essential for this to work, and double the normal jump vector generation time must be
observed. But when getting there "on a dime" timewise is essential, then this technique is the key. Most civilian vessels
don't bother.

IMO, this gives to coordinated jump a predictability of time in jump not coherent with most traveller literature.

MY proposal (for seccond paragraph) would be:

If double the jump preparation time is spent with all the affected ships in computer link via communication lines, roll usual time (124 + (2d x 6) hours) for the 'main fleet time' in jump. To know the exact arrival of each ship, modify this 'main fleet time' by (2d - 7) x 0.1 hours, yelding a variation of 30 min over or under calculated time. Most ships will arrive within minutes of each other, with the worst spread being up to an hour apart. Constant communication during the jump vector generate is essential for this to work, and double the normal jump vector generation time must be observed. But when getting there "on a dime" timewise is essential, then this technique is the key. Most civilian vessels don't bother.