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The Fleet Ship designs, strategies, and tactics.

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Old May 15th, 2021, 11:54 AM
Werner Werner is offline
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Default What are the top speeds of Standard Traveller Starships?

The procedure is this, the jump fuel tanks get fed into the power plant, the standard design has 4 weeks of operation with power plant fuel alone, the assumption is half the total operating time is used for acceleration, the other half for deceleration so the midpoint velocity is the top speed. Now just to be clear, the operating time of the ship is as time progressed on the ship, so as the ship approaches the speed of light, that time slows down relative to the rest of the Universe. I Think with ships capable of 4-g or better, relativistic velocities are hit upon by ships with jump-2 drives or better. This assumes the maneuver drive is reaction less and can produce its maximum rate of acceleration for the run time of the ship. I've calculated the top speed of the Scout/Courier to be 48% of the speed of light. Which of these ships has the fastest midpoint velocity if used in this way?
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Old May 15th, 2021, 12:43 PM
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I'm not clear of the ask here.

Are you how fast a ship can go if they use their Jump fuel to power the M-Drive? And using that number to come up with "total weeks of acceleration" divided by 2 for accel/decel, how fast would they be at peak? And you do or do not what to consider relativistic effects?

Perhaps if you showed your math for you Scout ship it would be clearer.
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Old May 15th, 2021, 01:17 PM
Werner Werner is offline
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Quote:
Originally Posted by whartung View Post
I'm not clear of the ask here.

Are you how fast a ship can go if they use their Jump fuel to power the M-Drive? And using that number to come up with "total weeks of acceleration" divided by 2 for accel/decel, how fast would they be at peak? And you do or do not what to consider relativistic effects?

Perhaps if you showed your math for you Scout ship it would be clearer.
The Scout/Courier has 20 tons of hydrogen in its jump fuel tank, its fusion power plant also runs on hydrogen and it retains 4 tons of hydrogen for its power plant so it can run for four weeks. Now 20 tons divided by 4 tons is 5 so the jump fuel is 5 times the amount of fuel for the power plant so it can run for 4 weeks. So we'll call 4 weeks a month, that means if the jump fuel is shunted to the power plant instead of the jump drive that ship can run for 6 months, 5 months on the jump fuel and 1 month on the power plant fuel for a total of 6 months of operation, that is 6 times 4 weeks or 24 weeks to be precise. The Scout ship can accelerate with its maneuver drive at 2g which we'll call 20 meters per second squared, so for ever second of operation the Scout/Courier can increase its velocity by 20 meters per second so if you do the calculation and divide the velocity after 3 months of continuous 2g acceleration by 300,000 kilometers per second, the maximum velocity comes to 48% of the speed of light and change. If you go past 72% of the speed of light, you have to start making relativistic calculations instead of adding 20 meters per second every second. There is a Starship travel times calculator: https://orionsarm.com/fm_store/RTTCalc.htm
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Old May 15th, 2021, 01:20 PM
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You may also want to specify a rule set.

For example if I use the CT 81 rules there is the secret jump 6 2000t ship in TTA with enough fuel for 22 weeks at 6g.

If you are going with 'standard' designs then it would have to be the ship with the largest fuel capacity - the 800t merc cruiser perhaps?
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Old May 15th, 2021, 01:51 PM
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Maximum speed = 84 hours acceleration at maximum Gee for any normal use.
1G = 10 m/s2 x 84 hours x 3600 seconds/hr = 3,024,000 m/s = 3024 km/s


Explanation: 84 hours is 3.5 days or 1/2 of a 7 day trip. Any longer trip would have been better accomplished via a 7 day jump, so this is your velocity at the turn around point just before you begin deceleration on a 7 day trip.
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Old May 15th, 2021, 03:03 PM
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With standard ship calculations, wouldn't you have to balance acceleration against how much fuel you can carry? That is, it might be better to have a lower, steady, acceleration for much longer than a high acceleration and just carry more fuel. You'd also have to consider if the ship has a way of collecting fuel as it goes.
On that, I don't recall seeing anything in the rules per se on collection of fuel as you travel but there is the Annic Nova with solar panels and those and batteries are in the rules, so it might be possible to build a ship with a near infinite amount of fuel available to it...
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Old May 15th, 2021, 03:11 PM
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Quote:
Originally Posted by atpollard View Post
Maximum speed = 84 hours acceleration at maximum Gee for any normal use.
1G = 10 m/s2 x 84 hours x 3600 seconds/hr = 3,024,000 m/s = 3024 km/s


Explanation: 84 hours is 3.5 days or 1/2 of a 7 day trip. Any longer trip would have been better accomplished via a 7 day jump, so this is your velocity at the turn around point just before you begin deceleration on a 7 day trip.
What if your jump drive is broke and there is no place nearbymwhere you can fix it? Let's say for instance you had an encounter with pirates and they destroyed your jump drive, the nearest starport is one parsec away, you still have all your jump fuel and your maneuver drive works fine. This is an unpopulated system, so there is no one to receive your distress call, and you just destroyed those pirate ships, so there is no help from those either!
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Old May 15th, 2021, 03:57 PM
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I have a different maximum velocity limit.


It's predicated on how fast the ship can be going and then maneuver out of the way of a rock or meteor swarm or ship debris.



So 3 factors-

  • Size of rocks/swarm/debris- figure a 1 km radius for ship size or less normal detection. Secondary would be avoiding ship size for larger ships.
  • Acceleration the ship is capable of to avoid threat.
  • Detection range vs. seconds available due to vee, and crew/computer reaction time to avoid.

A 1G ship will need a minimum of 100s or less accel vector to a side to create 1km of distance. Using CT civ detection of 150000 km, the question is how fast can your vee be before you can't make that clearance.



Put another way, you start getting into collision danger zones at vee higher then 150000 km every 100 seconds in this case. Multiply that by 10 to make a regular CT maneuver turn, 1.5 million km, or in 'G' terms that would be 150G- or 150V to make the distinction between current velocity and acceleration.


To go to the maximum via CT, 400000km detection and 6G, that's 4 million km and 16s reaction burn, so 2400V.


Higher velocities then is normal in an average game, but considerably less then C-fraction vee.


Outside of inner planet space the chances of running into such debris gets lower, but Aramis has covered the not-so-empty interstellar space and the impacts of even molecular gas at those speeds. Our game doesn't postulate shielding or materials up to that challenge unless you count the ablative nature of asteroid ships, so likely an upper speed limit there too.



Yes I am aware the reaction burn times/distances are 'fuzzy math', I'm just using the game's inherent maneuver mechanic to illustrate the dimensions of the problem set. Adjust as your gearhead heart sees fit.
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Old May 15th, 2021, 04:28 PM
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Quote:
Originally Posted by Enoki View Post
With standard ship calculations, wouldn't you have to balance acceleration against how much fuel you can carry? That is, it might be better to have a lower, steady, acceleration for much longer than a high acceleration and just carry more fuel. You'd also have to consider if the ship has a way of collecting fuel as it goes.
On that, I don't recall seeing anything in the rules per se on collection of fuel as you travel but there is the Annic Nova with solar panels and those and batteries are in the rules, so it might be possible to build a ship with a near infinite amount of fuel available to it...
If you're going that way, use a Bussard Ramjet. Collectors not only can't handle acceleration, but also would be shredded by hypervelocity impact with interstellar particles (let alone sizeable debris).

I recall something along the lines of .1c from one week at 1G (if you accelerate harder or for longer, you'll hit significantly diminished returns for the energy investment at higher fractions of c). Realistically, you'll probably want to avoid going much faster than .2c without SERIOUS armor or handwavium deflector shields. At those speeds there won't be a useful degree of time dilation.

Also, later versions of Traveller limit maneuver drive effectiveness past 100D (1000D at higher TL, if memory serves) of a world or star, precisely for the out-of-universe reason that it limits using starships as a relativistic kinetic weapons.
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