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Old 02-18-2022, 11:59 PM   #1
DaltonS
 
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Default [Query] Turley Starport Size

I am planning to use GURPS Traveller: Starports to design the starport for the planet Turley in the Empty Quarter sector. Its port size on the Imperial Encyclopedia site is 6 (which makes sense for a class V port on a major trade route). Unfortunately that route is the Saeghvung-Turley-Exile Run which is a chain of Deep Space stations spanning the Lesser Rift. Each of these stations has an estimated "annual flow of 15,000 passengers and 300,000 dtons of cargo" typical of port size 5 (which would be Turley's natural port size if it wasn't on a trade route). Should I use the official port size or the calculated one?
Dalton “was T:ST used for the official port stats?” Spence
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Old 02-19-2022, 12:41 AM   #2
dcarson
 
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Default Re: [Query] Turley Starport Size

Size 6 with size 5 maintenance budget because someone was overoptimistic?
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Old 02-19-2022, 06:37 AM   #3
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Default Re: [Query] Turley Starport Size

The traffic tables in Far Trader (from which the ones in Starports are drawn) were deliberately grainy, to make it possible to calculate by hand and because the whole thing is really just an estimate with a substantial degree of fuzziness. Nevertheless, it's possible to look "under the hood" and see what went into the final numbers:

A traffic level of 300,000 dton/yr is actually closer to size 5.5; the minimum for size 5 is 100,000 dton/yr. If Turley receives 100,000 dton/yr in system traffic (i.e., with Turley as destination or origin) plus 300,000 dton/yr in transient traffic (i.e., just passing through along the route), the combined 400,000 dton/yr amounts to size 5.6. If Turley's size 5 is closer to the maximum (e.g., 800,000 dton/yr, size 5.9), or there are other routes that send transient traffic through it, the port could easily break into size 6 (> 1,000,000 dton/yr).
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Old 02-19-2022, 11:11 AM   #4
DaltonS
 
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Default Re: [Query] Turley Starport Size

Quote:
Average traffic for a port will be three times the minimum for that port size. For instance, the average port of size 5 will handle 15,000 passengers per year.
This would make the estimated DSS capacities exactly average for a port size 5. Thing is all of Turley's transient J-2 traffic has to filter through them. Turley would have in-system traffic which Deep Space Stations don't have but that would mainly be supplying fuel to the stations on either side in the Saeghvung-Turley-Exile Run through Jump Tankers. (I designed one that could provide one-third of a station's weekly needs but it would require 2 tons of fuel for the J-2 jumps there and back again for every 1.4 tons delivered.) Note that Turley has to supply three times the fuel supply needs of the transient traffic; once for itself and twice for the neighboring stations. It's very likely that tanker traffic would exceed transient traffic by a significant margin. (I haven't worked it out yet because frankly the numbers scare me. ;) )
Dalton “good thing Turley has plenty of water” Spence
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Old 02-20-2022, 11:47 PM   #5
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Default Re: [Query] Turley Starport Size

Okay. I bucked up my courage to consider the tanker issue. From my notes on Deep Space Station requirements:
Quote:
Based on early feasibility studies, the DSS Project estimated an annual flow of 15,000 passengers and 300,000 dtons of cargo through these artificial starports. Those figured implied 300 passengers and 6000 dtons of cargo per week, or approximately five trade vessels per day. Unlike planetary starports, which may have multiple highports and downports, a single deep space station must manage all passenger and freight transfers coming through their region of space. To prevent each station from being overwhelmed by the occasional heavy traffic volume, naval architects created the deep space station design under the assumption that they may occasionally have as much as double the expected passenger or freight flow.
Example: For ships traversing the Saeghvung-Turley-Exile Run the maximum jump distance is two parsecs. According to “Determine Tonnage of Starships Served” on T:ST page 64 the raw figures would imply 10,500 dtons of shipping per week, which doubled for safety gives us 21,000 dtons per week. This traffic would use 4,200 tons of hydrogen per week (or 600 dtons/day) for the outgoing jumps. (Note: The estimated annual flows imply these stations have a port size of 5.)

The 5,000 dton jump tanker I designed will deliver one-third of the weekly shipping traffic's fuel requirements. Therefore in addition to the 21,000 tons of shipping the station has to handle 15,000 dtons of tanker traffic per week. Since each tanker requires 3,400 tons of fuel per mission (the payload plus two jumps' worth) the electrolysis unit at the Turley downport would need to produce 6×3,400 = 20,400 tons of hydrogen per week for the neighboring stations plus 4,200 tons weekly to be delivered by 7 daily trips of an 800-ton Oiler (T:FT p. 137) to the highport for the through traffic. (Let's round this up to 150 tons/hour so the Oiler can make one extra trip per week. ;) ) This is all without accounting for the system traffic related to imports and exports.

FWIW my "tanker" carries any fuel it isn't currently using to Jump in its cargo bay using collapsible tanks. As a result when each ship has delivered its payload to the station and refilled its hard tank for the return trip it has enough cargo capacity to carry 1/3rd of the station's expected cargo traffic with 400 dtons left over. (How about that! ;) )
Dalton “how big would the electrolysis unit have to be?” Spence

Last edited by DaltonS; 02-21-2022 at 08:06 AM. Reason: Added FWIW.
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Old 02-22-2022, 07:22 AM   #6
DaltonS
 
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Default Re: [Query] Turley Starport Size

Having mentioned the Jump Tanker/Freighter I designed above I thought it only fair that I shared the specs with you. Here they are, lovingly translated to BBCode from the HTML output produced by the ancient (2000) GURPS Traveller Ships program by Thomas Bont. (I've looked hard for something more recent to design GURPS Traveller ships by the old rules but couldn't find anything. ;) )
Quote:
5,000-ton Batillus-class Large Jump Tanker/Freighter, Bellamya (TL10)
This Jump Tanker is designed to replenish the fuel tanks of a Deep Space Station on the Saeghvung-Turley-Exile Run in the Empty Quarter Sector. In addition to the 1,000 ton hard fuel tank, the 20 collapsible tank modules can store 2,400 tons of fuel in the cargo holds. (Note: With its cargo capacity this design is a pretty good straight-up freighter outside the Saexile Run.) The 2 fuel processors can refine this in 150 hours (6.25 days) during the jump. After refilling the hard tank for the return trip 1,400 tons will be left to deliver to the station (which according to my calculations is exactly one-third of the projected weekly fuel consumption by station traffic). These projections assumed double the nominal traffic so three shipments a week should be more than enough to keep the station's tanks topped up.

This ship is highly automated (as evidenced by the software list) and while it may not be strictly necessary the flight crews of the auxiliary vessels will "stand watch" on the bridge during off-shifts. Each of the engineering crew does 8 hours (and 45 seconds) of maintenance duty per day. The duty cycle of each ship is four weeks with two of them spent in transit, 3.5 days at the station and 10.5 days at the base system getting refueled. With three ships visiting per week each station must have a fleet of a dozen ships to provide the fuel it needs.

Crew: 30 Total. 5 Bridge Crew (Captain, 1st Officer/Pilot, 2nd Officer/Navigator, Sensor/Comm Operator, Chief Engineer), 16 Engineering (6 Jump Drive, 8 Maneuver Drive, 2 Drive Hands), Medic, Turret Gunner, 7 Flight Crew.

Hull: 5,000-ton VGSL, Medium Frame, Standard Materials, Durasteel (Standard) Armored Hull (DR 100), Heavy Compartmentalization.

Control Areas: Basic Bridge(Complexity 7), Basic Security.
Code:
Communicator Range (mi)         Radio           Maser           Laser           Meson
Basic Bridge    50,000,000      0               100,000,000     0

Sensors Range/Rating (mi)       PESA            AESA            Radscanner
Basic Bridge                    20,000/37       100,000/41      2,000/31
Engineering: Engineering(52.6 dtons[2,192.89 MW], 40 Total Life Support), 150 Jump Drive, 161 Maneuver Drive(1.00 / 2.15 Gs, 6,440 stons thrust), 20 Cryonic Collapsible Tank(Fire 13), 1002 Cryonic Internal Tank(Fire 13, Loaded with 1,000 stons, 2 Scoops), 2 Fuel Processor(62.5 hours to refine Cryonic Internal Tank), 3 Utility(Doesn't cover fuel tank, cargo holds or vehicle bays.), 128.1 Man-Hours/day Maintenance.

Accommodations: 2 Luxury Stateroom, 10 Stateroom, Bunk Room, Sickbay(2 Patients), 7 Low Berth(28 Cryoberths), Complete Workshop(3 Users), Sm Entry Module(4 Users).

Misc: 32 Power Slice Adjustment (For efficency, remove power slices for the lesser of jump or manuver drives.), 2 Service Crew.

Armaments: 1 Pop Turret Battery of 1 (DR100).

Stores: 2400 Hold, 10 Vehicle Bay(10-ton Launch), 200 Spacedock(100-ton Oiler).

Statistics: EMass 2,680.11 stons, LMass 6,432.11 stons, Cost MCr712.46, HP 165,000, Size Mod 11, HT 12, CP 819.

Performance: Jump-2 (2), Acc L/E 1.00 / 2.40 Gs, Airspeed 2,096 mph, Skimming Airspeed 5,927 mph, Aerostatic Lift 6,440 stons.

Sample Times (Earth Std, Full Load): Orbit 00:00:14, Escape Velocity 00:00:19, 100D 00:06:23, Earth-Mars 04:13:34.

Code:
Software Package               Qty       % Utilization   Description
Anti-Hijack                     1        5.0000          C6, Criminology 15
Astrogation (Normal Space)      1        5.0000          C6, Normal Space Astrogation 16
Astrogation Jump 2              1        5.0000          C6, Astrogration (Jump) 15
Autonomous Operations           1       50.0000          C7, Starship Ops 14
Auto-Pilot (Jumpspace)          1        5.0000          C6, Jumpspace Pilot 16
Auto-Pilot (Normal Space)       1        5.0000          C6, Normal Space Pilot 16
Damage Control                  1        5.0000          C6,  Damage Control +6
Datalink                        9        0.0004          C1
Internal Security               1        5.0000          C6,  Electronic Ops (Sec Sys) +5
Library Data                    1        0.0001          C1
Personality Simulation (Full)   1        0.5000          C5
Totals                                  85.5005
Code:
System Name                     Crew            % Crew
Basic Bridge                    5 (5)           16.7
Jump Drive                      6 (6)           20
Maneuver Drive                  8.07 (8)        26.9
Pop Turret                      1 (1)           3.3
Service Crew                    2 (2)           6.7
Sickbay                         1 (1)           3.3
Vehicle Bay                     3 (3)           10
Spacedock                       4 (4)           13.3
Recommended Maintenance         0.0             N/A
Options
Crew arranged into 3 shifts
All times in DD:HH:MM format

Printed 2/22/2022 2:05:03 AM
Copyright © 2000 by Dalton S.Spence
BTW the names came from a supertanker class and specific ship from the 1970s. (What can I say, I'm an old fashioned guy. ;)
Dalton “still looking for more data on Turley Spence

Last edited by DaltonS; 02-25-2022 at 11:23 AM.
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