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Maximum Vacuum Speed

E

equilibrium

SOC-7
Hi there,

I'm prepping for a game of MT soon and while trying to sell the thing to a friend of mine he made a comment regarding the maximum vacuum speed of starships. He noticed that the max vac speed of an A-Class merchant is something like 1200km/h. Being somewhat of a space-nerd he quickly realised just how "slow" this was. He quoted some figures for the current shuttle saying it reaches something like 25000km/h when in orbit.

My question is, just what exactly does the max vacuum speed denote? I understand that the Maneuvre drive is measure in G's of accelleration but why have a maximum speed in a vacuum? I'm not as into that level of propulsion nerdity to care that much and "explained" that its probably to do with the space combat system and relative to other ships etc etc etc blah blah blah ;)

any explanations would be greatly appreciated


cheers

Jason K.
 
Off the top of my head I think its just used as a baseline for calculating atmospheric performance, which would be considerably less than the shuttle's orbital speed (which I think is closer to 18,000km/h to nit-pick ;) but what's a couple thousand kph between friends :D )
 
well the book and the ship constructor says maximum vaccuum speed... i'm willing to discount it for now but here's the example for a free trader i constructed with a 1G maneuvre drive...as for the 300,000kps thing.. where is that defined? I always thought the speed of light was about a thousand times faster than that..

Speeds:
ATMOSPHERE MAX CRUISE
Vacc: 1,200kph/750mph 900kph/563mph
Standard: 1,000kph/625mph 750kph/469mph
Thin: 1,500kph/938mph 1,125kph/703mph
Dense: 750kph/469mph 563kph/352mph
Very dense 250kph/156mph 188kph/117mph
 
Maximum vacuum speed in space might be some sort of "safe" maximum speed. After a certain point, the effects of hitting some sort of random, small debris in space is probably going to be near catastrophic. I've never seen that speed defined though, and at some point, you'll also start seeing relativistic effects.

The maximum atmospheric cruise speeds don't seem to make much sense for ships since ships appear to move faster in thin atmospheres than they do in vacuums. The atmospheric cruise speeds may take into account (in a hand wavy sort of way) the effects of being in a gravity well since not all of the available thrust can be devoted to moving the ship forward (some must be devoted to keeping the ship from falling).

That might explain why the speed is higher in a thin atmosphere: in a thin atmosphere, the ship gets some benefit from lift effects and can devote more thrust to moving forward while in a vacuum, more has to be devoted to lift. In a standard atmosphere, even less has to be devoted to lift, but the atmosphere is thicker and harder to get through.

Ron
 
I did some calculations on the maximum "safe" speed for CT starships, using STRIKER data for explosives and such. It's on the board here somewhere.

What I got was that an unarmored CT/HG/MT ship could reach about 200 kilometers per second (about 0.167% of lightspeed) before impacts with space dust would be dangerous. That works out to 720,000 kilometers per hour. Armored ships can do considerably better than that.
 
Atmospheric speeds are more limited by control than drag. I think the T20 values are too low, for the most part. 1G propels a low-sectional-density human body to 100mph (160kph), 120mph (192kph) in "clean" configuration (which is still rather dirty).

T20 non-streamlined ships are 75kph NoE, 200 Cruise, 300 Maximum even for 2G or 3G drive ships. That might make some sense if they relied on aerodynamics for flight controls, but they would not. Partial streamlining is about double, and streamlined about four times as fast.

Perhaps what MT means by "Vacc" is near-vacuum, what other versions call very thin. The speed is lowered because of lack of aerodynamic control. But again I think that is lame because grav control would eliminate most stability problems.
 
I never understood just why MT had a maximum speed for ships in a vacuum. I always just ignored it.
 
Equilibrium asked:
"...as for the 300,000kps thing.. where is that defined? I always thought the speed of light was about a thousand times faster than that....."

The speed of light is 3(point something, 08, I think) x10 to the power 8 metres per second, i.e. 300 000 000 (three hundred million) m/s.

300 000 km/s = 300 000 x 1000 m/s = 300 000 000m/s, so 300,000kps = speed of light (roughly).
 
Seems to me that is slightly slower than that. Also if you reach 97% (from recollection) light begins bending etc... Possibly the vessel becomes unstable...depending on how you interpet relativity.

If accuracy is part of the idea, perhaps 291000000
would be a max safe acceleration.

Just a thought.
Savage
 
my bad on the question of c ... i misread mps for kps ...

FTR google calculator defines C as

the speed of light = 299 792 458 m / s
 
Originally posted by equilibrium:
my bad on the question of c ... i misread mps for kps ...

FTR google calculator defines C as

the speed of light = 299 792 458 m / s
Click to expand...
F&S (1 or 2) redefines C and G for traveller purposes to be nice round numbes: 300,000kps C and 10mps^2 for G. Close enough for gaming pursoses... and it makes the math FAR easier!
 
Originally posted by Savage:
Seems to me that is slightly slower than that. Also if you reach 97% (from recollection) light begins bending etc... Possibly the vessel becomes unstable...depending on how you interpet relativity.

If accuracy is part of the idea, perhaps 291000000
would be a max safe acceleration.

Just a thought.
Savage
Click to expand...
Umm..yeah, but as you accelerate, your weight increases...at low fractions of C, this is immaterial at low fractions of C, but very significant as you get closer...you'll never actually reach C as your acceleration will slow down as you weight increases.

More likely is you'll run out of fuel long before you get close...especially if you want to save enough to slow down again


Being destroyed as you hit space 'dust' at massive speeds would also be a problem.
 
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