Template:Rocket engines/doc

Scope
This template is used exclusively for flown rocket engines used on orbital launch vehicles. The decision is on the intent of the vehicle, a suborbital mission of an orbital launch vehicle sill counts. Sub-orbital launch vehicles per se are excluded, anything atmospheric in not part of this. Pure orbital spacecraft, i.e. the payload of a launch vehicle, does not count.

Acceptable
 * Orbital launch vehicle main propulsion that was also used for suborbital vehicles. Example: Algol.
 * Orbital launch vehicle upper stages even if they are pure space vehicles but are never launched as payloads. Example: AVUM's RD-843.
 * Rockets engine of orbital upper stages, even if they are also used on spacecraft. Example: S5.92, used on Fregat, but also on Phobos 1 and Phobos 2 Mars spacecraft.
 * Main propulsion of stages that were also used as spacecraft: Example: Agena's XLR81.
 * Military engines when used for non-military or non weaponized applications. Example: SR-118 used on both Minuteman III ICBM and the Minotaur IV launch vehicle or the RD-869 used on the upper stage of Dnepr and the R-36 MUTTH MIRV.

NOT acceptable:
 * Spacecraft propulsion engines and motors. Example: R-4D.
 * Thrusters if they are used as the main propulsion of the spacecraft. Example: Dragon's Draco.
 * Military payloads like MARV, MIRV and other warheads breaking engines never used on non weaponized versions. Example: most ICBM.
 * Thrusters when used exclusively for station keeping, attitude control, reaction control system and/or as ullage motor.

Acceptability
This template is for rocket engines that have flown or are expected to fly in the near term. Engines not yet flown should be in Italics. The criteria for acceptability of unflown rocket engines are:

Option A Examples: SCE-200 or Raptor (rocket engine) as of 2016.
 * The engine has an article of at least Start class.
 * The engine has been test fired, at least at the flight component or sub-scale level.
 * The intent is for the rocket to be used in an orbital launch vehicle in the next five years.

Option B Example: RD-270 as of 2016, but NOT the IPD which lacked a thrust chamber and was not intended to fly.
 * The engine has an article of at least Start class.
 * The engine has been test fired at the flight model level (i.e. as intended to fly).
 * The engine was intended for use in an orbital launch vehicle but it was never actually used.

Categorization
Some guidance for placing rocket engines on the template:
 * Country: the country that counts is the designer's country. So, for example, the RD-120 was designed in Russia by NPO Energomash, and built in Ukraine by Yuzhmash, but counts as Russian. For countries that have disappeared, we display their main successor state, e.g. Russia for the Soviet Union.
 * Propellant: Care should be used not to increase too much the number of propellants. Exotic propellants like the RD-119 or the Nth variation of Hydrazine should all be clumped together.
 * Rocket families: Only different number variations should be included, and should be grouped by comma separation or, in more than two sequential numbers, through the use of the to word. For example the RD-0210 is presented as RD-0202 to RD-0206, RD-0208 to 0213, but the whole Merlin 1 family goes in one entry, not A, B, C, D, D Vacuum distinction.
 * Ordering: within each propellant and country the engines order should be strictly alphabetical.