A medley of missiles

[Captain Jonah]

So if safe add the astro effect, if inside 100D ...

As I understand the rules, it is not possible to leave jump space inside
100D, because the ship would be thrown out of jump space at the 100D
line ? :?

Leave jump space no, you come out at the 100D limit. Unless you are miss jumping and then anything goes. Entering jump space however is another case, you can jump inside 100D, you can if suicidal jump inside 10D but that is an auto missjump.

 

[rust]

Ah, I see, I did misread your previous post.

 

[rinku]

Where we disagree is that armour is needed to survive solar flare type events since just about every civilian ship above the "adventure ships" (scout, Free Trader, Far Trader) has no armour and would be toast if it jumped into a rad storm unless they are all basicly immune to non weapon rads.

Well, standard rules gives them 500 points just for having a hull, which suffices for most routine flares. It's the really big events that are going to be a problem, and they're a lot rarer. As far as why commercial ships don't all have the rad shielding described in High Guard... simple economics if only rare and big storms that are the problem (which I believe to be the intent). Rad shielding costs MCr0.25 per ton of hull... that's basically the cost of another ship. If you even lost one ship per hundred jumps due to radiation hazards, you'd think twice about adding it to all ships (the ship's crew may not agree). I suggest the loss figure would more likely be in the 1 per thousands or 1 per 10,000's, however.

One other thought I had, though... how wide are these events? Ships trying to avoid them have free choice of direction and can accelerate, unlike a planet. If we give a 1G ship an hour to evade to safe space, it can travel 64,000 km (doesn't need to turn around and decellerate, you see). Over a 2 hour timeframe this becomes 2.59 million km - maybe not enough time to totally avoid rads, but probably enough to keep the rads to treatable levels.

A further thought, but not one brought up in Traveller before that I'm aware of, is some kind of magnetic field. The hard radiation wavefront can't much be avoided, but will also peak and pass rapidly. It's the slower moving proton storm that is the problem... but that comprises of charged particles, so it should be possible to deflect it in this manner. That is, after all, largely how Earth survives them.

Edit: It further occurs to me that the critical manuever is to get the ship from where it emerges from jumpspace into the lee of the planet, even if it's still somewhat distant from the planet when it gets there. d=vt+(1/2at^2), after all, though for most purposes in this discussion we can ignore starting velocity as it should be matched with the target planet.

 

[Captain Jonah]

A further thought, but not one brought up in Traveller before that I'm aware of, is some kind of magnetic field. The hard radiation wavefront can't much be avoided, but will also peak and pass rapidly. It's the slower moving proton storm that is the problem... but that comprises of charged particles, so it should be possible to deflect it in this manner. That is, after all, largely how Earth survives them.

I touched on this a few pages ago, the theory came about in the 50s/60s or so but was never really researched then. Now it is actively being looked into on both sides of the pond.

This is a random sample from 1991 http://www.islandone.org/Settlements/MagShield.html

Here in the UK the Rutherford-Appleton Laboratory are doing some of the work, in the US its one of the Nasa offshoots i think. Again we are dealing with Traveller being a 21st century version of a game with a 1970s image of 1950s tech development tree. No insult to the origional version but the 1970s was a looooong time ago in terms of science

 

[Jame Rowe]

Inaccurate Jumps just dump the ship somewhere in the inner system, requiring a long space flight.

I bet you this is why there are so many UFO sightings - they don't mean to come here; they just don't know what the hell they're doing. :roll:

(But this is a good rule for Traveller too.)

 

[Captain Jonah]

Inaccurate Jumps just dump the ship somewhere in the inner system, requiring a long space flight.

I bet you this is why there are so many UFO sightings - they don't mean to come here; they just don't know what the hell they're doing. :roll:

(But this is a good rule for Traveller too.)

Pilot, Hey you frak head we just jumped out in front of the planet again.

Engineer, never mind, the locals are so stupid they never know whats happening out here. Just fly to the base and I'll fake the jump log. No one will never know

 

[locarno24]

Why do you equate the variable arrival time with jump inaccuracy? I can't see anything in the rules, or from the description of how jump travel works to support that. If you make your jump roll, you arrive where you plotted to.

Because if you don't arrive where you intended to when you intended to, the planet won't be there yet.

 

[rinku]

Why do you equate the variable arrival time with jump inaccuracy? I can't see anything in the rules, or from the description of how jump travel works to support that. If you make your jump roll, you arrive where you plotted to.

Because if you don't arrive where you intended to when you intended to, the planet won't be there yet.

Well that's basically my point. You exit normal timespace at one point and a variable time later unrelated to the jump distance you enter normal timespace again. It doesn't really matter if your inaccuracy is temporal or spacial for a normal inaccurate jump (misjumps are another matter. A Referee is in their rights to send them into the far future or even past if they want to).

The thing is, a badly failed jump that dumps you on the other side of the system uses exactly the same time formula as the most pristinely accurate one.

 

[DFW]

Because if you don't arrive where you intended to when you intended to, the planet won't be there yet.

Correct. The 6D6 hours time variable means that you can almost never exit exactly where you want to relative to a moving body in the destination system. Thus, jumping directly into the planetary "shadow" is close to impossible.

 

[Captain Jonah]

Consider the average time of a jump is 148 + 6D or 169 hours.

Orbital speed of earth is 107, 826 Km per hour. If the average jump time gets you there spot on then fine. However each hour over or under leaves you either ahead or trailing.

Arrive 10 hours early and you are 1,078,260 Km in front of the earth and need to head towards it then match velocity with it when you get to it as you are going the wrong way.

Arrive 10 hours late and you are not only more than a million Km behind it but it is racing away from you as well. For a M1 ship thats upwards of 4 hours if you are in front and 10 odd hours if you are behind. This is from an accurate jump where the time is variable.

Now you can match vector and velocity with the target world as part of the jump astrogation but you are still ending up many hours away. A maximum time late jump can take you a day to catch up with the world and land.

Trying to land inside the earths magnetosphere requires you to be within half an hour of spot on, an our out either way is outside the safe area.

A jump that isn't accurate can leave you days away from the world.

Personaly I think an accurate jump should get you there when and where you want otherwise its not much point calling it an accurate jump.

 

[DFW]

Orbital speed of earth is 107, 826 Km per hour.

What is the speed of the shadow 100 diams BEYOND the Earth? MUCH faster than what the Earth is actually travelling...

Using Kepler's Second Law (A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.) it could be figured out.

 

[locarno24]

Probably not that much faster.

Using the (very simplified) model of a circular orbit (I know it's not but it'll do when working out orders of magnitude); the angular velocity of the magnetopause shadow won't be different from the planet itself (as the shadow will remain centred along the line mentioned, straight out from the Sun through the Earth).

Applying the same angular to an increased radius represents an increased velocity - but not massively increased as it's going to be the same proportional increase as 1 AU: 1 AU + 100 Earth Diameters


149,597,871 Km: (149,597,871 + 12,756 x 100) Km

149,597,871 Km: 150,873,491 Km

which is a bit less than a 1% increase. Obviously it will be slightly more than this at the 'corners' of an eliptical orbit, but the length of the shadow just isn't really that much in comparison to the earth/sun distance.

 

[DFW]

That's correct. An additional ~1% distance to missing the target.

 

[Captain Jonah]

That's correct. An additional ~1% distance to missing the target.

1% either way is nothing much when you have a variable of 3 to 18 hours either way and need to be 35 mins from exact to land in the shadow.

Unless an accurate jump is spot on 169 hours you are going to be hundreds or millions of km off when you arrive.

 

[DFW]

Unless an accurate jump is spot on 169 hours you are going to be hundreds or millions of km off when you arrive.

Yep. But, as someone eluded to earlier, if we lost one out of every 1000 commercial airline flights, there would be no move to modify the airplanes...
:shock:

 

[rust]

Yep. But, as someone eluded to earlier, if we lost one out of every 1000 commercial airline flights, there would be no move to modify the airplanes... :shock:

It would depend a lot on who was on that lost aircraft ...

 

[DFW]

It would depend a lot on who was on that lost aircraft ...

Really? Assume average passengers like todays airline traffic.

 

[rust]

Really? Assume average passengers like todays airline traffic.

Add a VIP or a celebrity or two, or have an entire sports team or a whole
class of school kids on board (as we had it during the Überlingen crash),
and suddenly things begin to move and officials hurry to check and im-
prove the regulations.

 

[DFW]

Add a VIP or a celebrity or two, or have an entire sports team or a whole class of school kids on board (as we had it during the Überlingen crash), and suddenly things begin to move and officials hurry to check and improve the regulations.

I'm thinking of our regs. One or two crashes due to preventable situation and the whole thing gets turned upside down. No celebs needed. But, each country is different in how strict or lax safety regs are in this area.

 

[Captain Jonah]

Jumping in outside of the spot on point is more annoying than dangerous unless you are dealing with flares or pirates or comerce raiders or come in damaged or.........

Coming in 15-18 hours early or late puts you a long way from all those military ships standing guard and rescue ships at the orbital bases.

With only 2 hours of air in the rescue bubbles even if you pack extra air stores into each one the air is going to get a bit thin

The fact that jumps are so messy even when done properly is likely a matter of some annoyance for those important passengers but the fact that they would happen so often will be making the system defence commanders have kittens.

If there is any possibility of hostile action in system, pirates etc, then they have to secure an area up to 18 hours either side of the planets position in its orbit. With earth thats getting on for 2,000,000 km each side. Two hours plus with a M6 ship that is ready to go. Plenty of time for a quick smash and fade from a lurking corsair and at that range unless you have a network of sensors proceding and trailing anything happening will be far outside planet based sensor range.

If even a properly worked out jump dumps you that far away the lurking pirate thing becomes doable. With scores or hundreds of ships visiting a busy world you will have half a dozen at least a day at the far ends of the jump in range. The richest worlds or those with strong naval presences will be ok but smaller or poorer worlds without vast fleets will not have the ships to cover everywhere at once.

To me a properly worked jump calculated by a decently skilled astrogator that is accurate should drop you in 169 hours at the 100D limit.

Something that drops you a day or more in travel time away while not a missjump hardly deserves the name accurate