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Old 02-21-2010, 03:56 PM   #1
Phil Masters
 
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Default Vehicles (3e) - Maglev Speeds?

I recently started a Transhuman Space campaign set on Mars, and the PCs, having just come down the elevator, were required to pick up a train on the equatorial railway to their next destination. At which point, my train-geek players raised somewhat quizzical eyebrows at the performance quoted for these trains in In the Well - all sub-200 mph, no more than on a par with the best TL8 wheeled trains and much less than the best performance of extant TL8 commercial maglev transport systems (working in much higher gravity, note). In other words, a bit underwhelming and not very skiffy.

I confess that I've not looked at the 3e Vehicles maglev vehicle construction/performance rules properly yet; can anyone say if this apparent feebleness is an artefact of the assumptions of that book, of the assumptions made about Mars in In the Well, or what?
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Old 02-21-2010, 05:54 PM   #2
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Default Re: Vehicles (3e) - Maglev Speeds?

As far as I can tell (and maybe it is there and I'm just missing it), none of the entries for maglev cars in In the Well include what their streamlining is. Doing a quick reverse-engineering using Vehicles indicates that the streamlining for the passenger car is about 8 -- between "very good" and "superior". To match the Shanghai maglev train I need total SI of around 37 (or 31 if the vehicle has a "responsive structure"). That's streamlining between "excellent" and "radical". The guidelines in Vehicles (p. 11) suggest that "slow but highly-streamlined craft" should have "very good" streamlining, but presumably that increases with TL...

Anyway, it definitely doesn't have to do with assumptions made about Mars (both Vehicles and ITW are clear that top speed depends on mass, not weight). But it might have to do with assumptions made by the writers of the book--without an explicit entry for streamlining, it's hard to tell.
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Old 02-22-2010, 01:30 AM   #3
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Default Re: Vehicles (3e) - Maglev Speeds?

Quote:
Originally Posted by jalapeno_dude View Post
As far as I can tell (and maybe it is there and I'm just missing it), none of the entries for maglev cars in In the Well include what their streamlining is. Doing a quick reverse-engineering using Vehicles indicates that the streamlining for the passenger car is about 8 -- between "very good" and "superior". To match the Shanghai maglev train I need total SI of around 37 (or 31 if the vehicle has a "responsive structure"). That's streamlining between "excellent" and "radical". The guidelines in Vehicles (p. 11) suggest that "slow but highly-streamlined craft" should have "very good" streamlining, but presumably that increases with TL...

Anyway, it definitely doesn't have to do with assumptions made about Mars (both Vehicles and ITW are clear that top speed depends on mass, not weight). But it might have to do with assumptions made by the writers of the book--without an explicit entry for streamlining, it's hard to tell.
_Vehicles_ p.166 says vehicles have the effect of radical streamlining in vacuum or trace atmosphere. Also, I think there was some reference to a JMF essay about Martian railroading, but that might be the other GURPS book about Mars.
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Old 02-22-2010, 02:41 AM   #4
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Default Re: Vehicles (3e) - Maglev Speeds?

Aside from game mechanics, it seems likely that that the Martian maglevs are just slow because they're cheaply built.
In the Well claims a construction cost of a minuscule million dollars a mile, and for that you're not going to get superbly engineered laser-straight trackwork drilling through mountains and bridging valleys. The Martian track is going to take advantage of the low grav to be as lightly built as possible and will loop around and over the terrain rather than indulge in expensive civil engineering works. It's a frontier railway, not a Shinkansen system.
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Old 02-22-2010, 02:48 AM   #5
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Default Re: Vehicles (3e) - Maglev Speeds?

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Originally Posted by dirtysnowball View Post
Aside from game mechanics, it seems likely that that the Martian maglevs are just slow because they're cheaply built.
You may well be right. At that point, though, it might have been smarter of the builders to ask if they really needed maglev technology. Might old-fashioned wheels have been cheaper to build and also to run (and also safer in a frontier, somewhat-geologically-unstable environment)? Or does cheap fusion power mean that you might as well make all your transport systems properly skiffy-kewl?
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Old 02-22-2010, 03:45 AM   #6
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Default Re: Vehicles (3e) - Maglev Speeds?

Why maglev? Umm...

Conventional wheel-on-rail systems may suffer from serious traction problems on Mars. Compared to Earth trains, the lower gravity means there's less weight to keep your train stuck to the track so it will derail more easily (requiring broader curves and lower speeds for safety) and can't apply as much power (or braking) before the wheels start to slip. Unconventional systems like rubber tyred wheels, linear motors or monorail arrangements that clamp the train to the track might help, but then you're losing the simplicity and efficiency of conventional rail.

Maglev, on the other hand, works better in Martian gravity. Holding the track magnetically it can take tighter turns faster and climb steeper inclines. Without moving parts or metal-on-metal friction it offers lower maintenance. With its monorail track carried up on pylons it won't be buried in the next sandstorm, and with the whole structure webbed with sensors the track will safely shut itself down if something gets damaged. The track could even be smart enough to actively move to compensate for unstable terrain.

And maglev is more excitingly skiffy.
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Old 02-22-2010, 02:38 AM   #7
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Default Re: Vehicles (3e) - Maglev Speeds?

Quote:
Originally Posted by jalapeno_dude View Post
As far as I can tell (and maybe it is there and I'm just missing it), none of the entries for maglev cars in In the Well include what their streamlining is. Doing a quick reverse-engineering using Vehicles indicates that the streamlining for the passenger car is about 8 -- between "very good" and "superior". To match the Shanghai maglev train I need total SI of around 37 (or 31 if the vehicle has a "responsive structure"). That's streamlining between "excellent" and "radical". The guidelines in Vehicles (p. 11) suggest that "slow but highly-streamlined craft" should have "very good" streamlining, but presumably that increases with TL...

Anyway, it definitely doesn't have to do with assumptions made about Mars (both Vehicles and ITW are clear that top speed depends on mass, not weight). But it might have to do with assumptions made by the writers of the book--without an explicit entry for streamlining, it's hard to tell.
A quick look at a picture suggests that the Shanghai trains have neat wedge-like noses, but I'd hesitate to call their streamlining "radical". And the Martian atmosphere is markedly thinner than Earth's, though far more than "trace".

I'm guessing that either the In the Well designs are rather under-powered, or the Vehicles system has a bit of a glitch here. Might be interesting to try and do the Shanghai system under Vehicles, then advance the TL a bit to see what happens to the numbers.
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