Running dark
Running dark means cutting power and stowing the radiators so a ship is harder to spot, and the price is waste heat that has nowhere to go.
22 numbers, 7 with an outside source
- A0 numbers at grade A
- B2 numbers at grade B
- C3 numbers at grade C
- D2 numbers at grade D
- E15 numbers at grade E
Functionality
2 topics
Thermal signature
- There is no hiding in space, because a crewed hull always glows against the cold.
- The harder your drive burns, the further off pirates spot you, so big fast ships get jumped more.
- A richer fuel grade burns brighter too, because its faster exhaust carries more power at the same thrust.
Silent running
- On any transit day you can stow the radiators and run dark, which drops you off pirate sensors.
- Silent running cuts the day's odds of a contact to 35% of normal.
- The catch is heat. Every system aboard draws power, and all of that power ends up as heat inside the hull.
- With every system running, most hulls fill up in about a day, and past that the heat starts to cook the ship.
- The engineer sheds systems while you run dark, so the heat builds slower and you stay dark longer.
- STANDING ORDERS > RUNNING DARK sets how many, and quotes what a dark day without each one costs.
- The air plant is never shed.
- One day of normal cruise vents it all, unless the radiators are shot away.
Values
22 numbers: 2 B, 3 C, 2 D, 15 E
Each value is read from the game code. Sort by any column heading, or filter by grade or by a word.
| Quantity | Value | Grade | Source | Why this value |
|---|---|---|---|---|
| Thermal signature of a light, medium and heavy craft with the drive off | LIGHT CRAFT 8, MEDIUM CRAFT 12, HEAVY CRAFT 18 signature points | EAuthored | Atomic Rockets, spacewardetect, What If I Run Silent And Cold? | The mirror gives detection range from surface area and temperature, but no point scale, so the game chose three steps by size class. |
| Signature added for each m/s^2 of fitted acceleration | 1 points per m/s^2 | EAuthored | Atomic Rockets, spacewardetect, Surely Sheer Distance Will Hide Engine Burns | The mirror says a burning drive is far brighter than a habitat but gives no scale, so the game chose how much each unit of acceleration adds. |
| Share of the baseline a dark hull keeps | 0.35 share | EAuthored | Atomic Rockets, spacewardetect, What If I Run Silent And Cold? | No source gives a dark share. The game chose it so a dark crewed hull stays visible, as the mirror says a 285 K habitat does, but harder to find. The sources are silent on this figure. |
| Signature below which a hull adds no contact chance | 20 signature points | EAuthored | No source recorded | No source gives a point where a ship starts to draw contact. The game chose it so small quiet hulls add no chance. |
| Contact chance added for each signature point above that | 0.5 points of chance | EAuthored | No source recorded | The mirror gives detection range, not a contact chance per signature point, so the game chose this exchange rate for play. The sources are silent on this figure. |
| Share of the day's contact chance left while dark | 0.35 share | EAuthored | Atomic Rockets, spacewardetect, There Ain't No Stealth In Space | The mirror says no real stealth exists and gives no odds for a dark ship, so the game chose how far going dark cuts the day's contact chance. The sources are silent on this figure. |
| Air plant draw for each person aboard (never shed) | 2,000 W | DAnalogy | Atomic Rockets, realdesigns3, HOPE (BNTR) crew vehicle, power budget | The mirror lists life support at about 30 kWe for a crew of six, which is about 5 kW a person. The game splits that among three loads by choice. |
| Recycling draw for each person aboard | 1,000 W | CDerived | Atomic Rockets, lifesupport, Water (TransHab water management subsystem) | The mirror lists the TransHab water recovery unit at 6,090.7 W for a crew of six, which is 6,090.7 / 6 = 1,015 W a person. |
| Crew services draw for each person aboard | 2,000 W | DAnalogy | Atomic Rockets, realdesigns3, HOPE (BNTR) crew vehicle, power budget | The mirror lists life support at about 30 kWe for a crew of six, which is about 5 kW a person. The game splits that among three loads by choice. |
| Machine shop draw for each rating point | 2,000 W | EAuthored | No source recorded | The mirror gives no power for a ship's machine shop, so the game chose a few kilowatts for the lathes and welders at each rating point. The sources are silent on this figure. |
| Reefer draw for each tonne of cold cargo | 200 W | CDerived | Reefer container power draw, actual power consumption of reefer containers | A container handbook gives about 4 kW for a 20 ft reefer and about 7 kW for a 40 ft reefer. A freight forwarder lists payloads of 27.4 t and 27.7 t. That gives 146 W per tonne and 253 W per tonne. The game's 200 W per tonne lies between the two. |
| Reactor plant's conversion: heat on the loop is each watt drawn divided by this | 0.25 share | BSecondary | Atomic Rockets, power, Space Nuclear Power Program (Prometheus and SAFE-400 figures) | The mirror lists the SAFE-400 heat-pipe reactor at 400 kWt for 100 kWe, which is 25 percent, and Prometheus at 1 MWt for 200 kWe, which is 20 percent. |
| Loads the engineer sheds by default while dark (from the top of the voyage bill) | 3 loads | EAuthored | No source recorded | The game chose how many loads the engineer sheds first while dark, so a default dark day costs comfort and repair before it costs cargo. |
| Fatigue each hand gains a dark day without crew services | 3 fatigue | EAuthored | No source recorded | No source gives a fatigue figure. The game chose it to equal the daily strain of general quarters. |
| Hull integrity lost each day past capacity | 12 integrity | EAuthored | No source recorded | The game chose a small daily hull loss for a hull that cooks, so the cost is real but never kills on its own. |
| Heat ceiling while dark, as a multiple of capacity | 2 times capacity | EAuthored | No source recorded | The game chose how far stored heat can climb past capacity, so a hull that stays dark too long still has a limit. |
| Heat the loop holds before the hull cooks (getheatcapacity returns this for every hull) | 32 heat units | EAuthored | Atomic Rockets, spacewardetect, Section 3: Stealth Problems Overview | Authored from the sandbox jacket size and kept equal for every hull. The mirror gives only that an ice heat sink absorbs 1 kW at 1 kg of ice per 7.8 minutes. |
| Enemy accuracy penalty against a dark ship in a fight | 30 accuracy points | EAuthored | No source recorded | The mirror gives no aim penalty against a dark ship, so the game chose how much a hostile loses its firing solution. The sources are silent on this figure. |
| Heat a fight adds while dark | 10 heat units | EAuthored | Atomic Rockets, heatrad, Radiator vulnerability | The game chose a heat cost for going dark mid-fight, because stowed radiators shed nothing. |
| Base daily contact chance in travel | 10 percent | EAuthored | No source recorded | The game chose a base daily contact chance for travel. No source gives a rate for meeting another ship on a lane. |
| Carbon dioxide a person adds to the air, per day, as a volume | 0.504 m^3 per person per day | CDerived | Atomic Rockets, lifesupport, Carbon dioxide levels (0.998 kilograms a day) | NASA says each astronaut exhales 0.998 kilograms of carbon dioxide a day (the page); the game divides by 1.98 kilograms per cubic meter, a handbook density for the gas at 0 C that was not reopened here (UNVERIFIED). |
| Share of the cabin air in carbon dioxide at which the crew turns drowsy | 0.01 share of air | BSecondary | Atomic Rockets, lifesupport, Carbon dioxide levels (0.04, 1, 3, 5 percent) | The page lists drowsiness at 1 percent carbon dioxide, and the game uses it as stated. |
Real-world basis
7 points
- A warm object shows against the 3 K background of space, so a crewed ship glows.
- A crew needs a room near 285 K, so even a ship with its drive off glows in infrared.
- A sensor sees a ship farther as its surface gets hotter and larger: range grows with the square of temperature.
- A drive burn is far brighter than a habitat, and it also reveals the ship's mass and velocity.
- Refrigerating the ship does not help, because a heat pump needs power and makes more waste heat.
- A ship can hold heat in a sink for a short time, so going dark always has a time limit.
- So hiding is only partial: a dark ship is harder to find without a wide sensor net, but it is never invisible.
Game and reality differences
6 points
- The game lets a dark ship cut the day's contact odds. The mirror says no real stealth exists. The code comment says a dark hull is cold enough to slip past hostiles without a real surveillance net.
- A dark hull never reaches zero signature, because the crew still breathes. This matches the mirror's point about a 285 K habitat.
- The signature is a size baseline plus the fitted acceleration, scaled by the square root of the fuel grade's exhaust speed. A real burn's heat follows thrust power, and the scale is authored.
- Stored heat is an abstract loop with a fixed capacity, authored and equal for every hull. A real heat sink lasts minutes, but the game allows a dark day or more.
- Venting heat on a normal cruise day is a game rule. The pages read give no vent rate for a ship that deploys its radiators again.
- Going dark mid-fight is a separate rule from the transit order, with an enemy accuracy penalty and extra heat.
Source absences
4 points
- Atomic Rockets does not provide values for the following:
- Contact chance for a dark ship.
- Odds that a given hunter finds a dark ship.
- Days a hull can stay dark. A real ship has no abstract heat capacity.
- Sensor net or area search rule. The contact roll stands in for one.
Influences
1 work
- Elite Dangerous (game): silent running mode: cut power and run dark to avoid detection
Sources
5 documents
- Atomic Rockets, spacewardetect, What If I Run Silent And Cold?: Detection range for a silent ship is 13.4 times the square root of its projected area times its temperature squared, in km. A 285 K habitat stands out against 3 K. A 1,510 m^2 hull at 273 K could be seen from about 38.8 million km. "will stand out like a search-light" (all uses)
- Atomic Rockets, spacewardetect, Surely Sheer Distance Will Hide Engine Burns: A burning drive is seen far away. The example gives 1.2 billion km for a chemical drive and 25 billion km for an ion drive. (all uses)
- Atomic Rockets, spacewardetect, Section 3: Stealth Problems Overview: A ship that hides while coasting becomes visible as soon as it burns, and the burn reveals its mass and velocity. Heat sinks are impractical over long periods: each kW of heat needs 1 kg of ice every 7.8 minutes. (all uses)
- Atomic Rockets, spacewardetect, There Ain't No Stealth In Space: The page states that space stealth is nearly impossible, except for limited cases such as hiding behind a planet. (all uses)
- Atomic Rockets, heatrad, Radiator vulnerability (text beginning 'Solutions for reducing the vulnerability of radiators'): If all radiators are retracted the ship must use heat sinks. That works only for very short periods. (The page's own boil-off time is wrong by about six times, so it is not used: see the heat note.) (all uses)