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"Dawn" Xenon Engine — variable thrust now in SE!

"Dawn" Xenon Engine: a variable-thrust, variable-specific impulse thruster with custom fuel and custom mechanics.

This engine is intended to fill the gap between infinite "ion" thrusters and close-to-useless hydrogen thrusters, especially on small ships.

First, the most interesting feature is variability. This engine has three different modes, which allow to increase fuel input to achieve higher thrust levels. Modes can simply be switched from terminal, from hotbar or by Programmable Block: for example, for a small ship thruster with a base thrust of 64 kN you can raise the consumption by 3x or 9x to achieve 128 kN or even whopping 196 kN, however the latter is kind of 'war emergency power' mode and most likely be used in combat or other critical situations.

Second, the used fuel type is Xenon. It can be acquired from cometary and asteroid ice using Electromagnetic Isotope Separators, but this won't be your primary method of fuel generation: electromagnetic separation is quite slow, power-hungry and not very efficient. The best method of gathering fuel are the Xenon Ramscoops: using gravity generator components, they can create a 'net' and catch xenon atoms from interplanetary gas. Their efficiency is depending on several factors, but the main ones are your speed (zero speed = no yield, so get moving!), ramscoop's facing relative to ship's flight direction (placing a ramscoop backwards will not do anything good, until you are flying backwards), and presence of atmosphere: xenon is too rare to be collected efficiently near planetary ground, but it is present in considerable amounts throughout the space. However, the really abundant source of xenon gas is the upper atmosphere: at about 1/4 the pressure of Earth sea level, the collection rate is more than 4 times than in space!

Third, they are different in costs: while they require a substantial amount of Iron, Silicon and Gold, they do not use rare Platinum, which makes them easier to assemble, and an ideal method of early-to-middle game propulsion.

Warning: the mod is work-in-progress and most balance values are likely to change. I would like to hear your opinion on balance tweaking, of course!

Related Links:
— Known Bugs
— F.A.Q.: read it before asking in comments, comments asking questions which are already in FAQ will be removed
— Bug Reports
— Use Xenon Fuel Data script if you want to have a real-time readout on your current Xenon amounts, burn time and remaining Delta-V.


Credits:
— Initial idea, preliminary balancing and Variable Thruster script are made by Cheetah (yes that's me! :P)
— Xenon Engine and Xenon Tank models are lovely handcrafted from ground zero by Vicizlat
— Ramscoop Models and the original Hydrogen Ramscoops code are (c) to Phoenix, used and enhanced with his permission
— Shoutout to Cython for his help to figure out the ModAPI oddities
— And a shoutout to whoever made the KSP's Near Future Propulsion mod for the inspiration!