Difference between revisions of "Electric charge"

Revision as of 18:04, 31 July 2013

Electric charge, also called electricity or energy, is a resource that is needed to operate various parts in the game. It is critical for unmanned spacecraft, which are generally uncontrollable without any electric charge.

Consumption and requisition

Unmanned satellite cores constantly use 1.7 or 3.0 units of Electric Charge per minute. Therefore they require a source of energy for missions longer than a few minutes, e.g. short engine burns at regular intervals can be used to keep a probe alive. Lights and instrumentation use small quantities of electricity as well, but only when switched on. Ion engines, reaction wheels and rover wheels require particularly large amounts of electricity to operate.

Sources

Engines

Many rocket and jet engines can produce electricity. The exact output varies based on throttle level, and engines not running will not produce any electricity. The adjacent table shows which engine produces how much energy at full throttle. Engines not listed do not produce electrical energy. As jet engines only run in a oxygen atmosphere, they only generate electricity in Kerbin's or Laythe's atmosphere.

Solar panels

A solar-powered satellite

Solar panels are a lightweight source of electrical energy. However, they need direct sunlight to work, so they won't produce electricity on the night side of a planet, in the shadow of a spacecraft or during eclipses of the sun, although the craft is illuminated while in an eclipse. Due to this unreliability, it is recommended to have some energy storage as a buffer when supplying a craft solely with solar panels.

All panels except for the OX-STAT Photovoltaic Panels need to be extended using the right-click menu or action groups. on them before they will generate energy. Unpacked solar panels are very fragile and will disintegrate when experiencing atmospheric drag, so keep them retracted during liftoff, aerobraking maneuvers or atmospheric re-entry.

Their energy output depends on their distance and orientation to the sun. Except for the OX-STAT Photovoltaic Panels, all solar panels will orient themselves automatically to a certain degree.

They generate more electricity the closer to the Sun they are located. However, they do not currently use the inverse-square law. Rather, they follow a spline curve of 3 piecewise cubics defined from 4 points:

Radioisotope thermoelectric generator

The PB-NUK Radioisotope Thermoelectric Generator is a constant and reliable source of energy which doesn't require any sunlight and is much more resistant to atmospheric drag than solar arrays. Unfortunately it has a very unpractical shape and is significantly heavier than solar panels with a comparable output of electricity.

Launch Clamps

TT18-A Launch Stability Enhancers provide attached craft with 1.0 charge units per second per clamp and thus prevent running out of energy on the launch pad.

Storage

Storing electric charge helps a craft survive longer without energy supply, deal with peak loads (such as the use of ion engines) or bridge time gaps when solar panels aren't usable. The following parts store energy:

• Unmanned command modules offer very low capacities and constantly consume energy.
• Manned command modules offer significant storage capacities and do not consume energy but are relatively large and heavy.
• Batteries are small and offer high storage capacities at the same time.
• The Probodobodyne RoveMate functions like a large low-capacity battery.

All energy storage available to a craft is fully loaded at launch.

Batteries

The available batteries have all the same capacity/mass ratio of 50 g/E or 20 E/kg.