Kraken Drive

A Kraken Drive, also called a K-Drive, is any assembly that lets the player control a vehicle's position using any of the Deep Space Kraken bugs. Kraken drives can be assembled with stock parts, and are of interest due to their ability to propel or halt ships effectively forever, at no cost.

Background

Before Krakensbane was introduced in v0.17, the Deep Space Kraken generated phantom forces that would act on vessels moving at very high velocity. Noticeably, when moving at extremely high velocity ex. on an orbit taking the player's ship close to the Sun, the player's orbit would visibly change due to intense Kraken-induced acceleration.

Krakensbane significantly reduced phantom forces but did not remove them entirely. Physics errors can still be magnified, and even controlled, by building certain assemblies. This is the basis of the Kraken Drive.

Use and "operating modes"

Since Kraken drives are usually built using some assemblage of landing legs or other moving part (ex. aircraft gears) tilted so as to clip back into the vessel when extended, they can usually be toggled on and off.

Kraken Drives seem to have two modes of operation: Low-, and high-velocity, with the presence of atmosphere as a possible third variable. At low velocities, below ~800 m/s in the vicinity of Kerbin, many K-Drives will accelerate their vessel to a constant velocity that tends to be in the range of 0–5 m/s. Above 800 m/s over Kerbin, many K-drives will begin to exert constant acceleration on a ship.

This discrepancy between operating velocities can be dangerous to vessels attempting to slow down using a K-Drive. If the vessel falls below the cutoff velocity, but is moving much faster than "low velocity", activating the K-Drive can make the drive try to slow itself to low velocity, instantly.

Alternatively, some K-Drives seem to serve as anchors, holding the vessel fixed to a position relative to the parent body.

Certain K-Drives seem to function differently in atmosphere as well as, or rather than, switching modes based on velocity.

There is a theory that the ARM Advanced Grabbing Unit could be used to create a Kraken Drive, but no successful craft has been made.

Construction

There is as yet no sure method for building a Kraken Drive. Performance can vary depending on the precise placement of parts, and may depend on hardware specifications, although this is by no means certain.

What is known is that K-Drives are usually constructed out of some moving parts ex. legs or wheels, and some structural parts, as well as reaction wheels. Legs and wheels are usually arranged in such a way that they will clip into other parts of the spaceship when extended. This can be seen in many K-Drive threads.

The base concept of the Kraken Drive is that part A pushes against part B with force and instead of tearing the ship apart or doing nothing (as would be realistic) it actually applies an intravehicular force with no equal and opposite force, thus producing measurable, and in some cases extreme, acceleration.

Landing legs work because landing leg feet will collide with parts of your craft when deployed and because the suspension animation is spring loaded and applies force when compressed to return to an uncompressed state. The greater the distance of compression (and the more legs compressed), the greater the force applied.

History

At some point between December 2012 and January 2013, KSP Forum user A Fat Pokémon created a vessel in v0.18 called the "FTL Egg" which was an assemblage of struts, structural pieces, and ladders which, when boarded by a Kerbal, took advantage of phantom forces generated when Kerbals climb ladders to generate linear acceleration capable of propelling the Egg and its rider at high velocity across the solar system. Despite garnering the attention of several tens of thousands of viewers at the time, the Egg did not immediately lead to further developments in harnessing physics glitches for spacecraft propulsion.

On February 3, 2014, Comrade Jenkins created a thread in the General Discussion section of the KSP forums entitled "Harnessing the Kraken: Eeloo in 11 Hours!" asking players to post about their encounters with physics glitches and what caused them, in hopes of compiling enough data to create a useful "drive" taking advantage of errors to propel a spacecraft to interplanetary velocities. Over the next 16 days, the thread garnered 204 replies and received numerous submissions of candidate "Kraken Drives" varying in reliability and function. The thread in turn spawned several spinoff threads, including a Spacecraft Exchange submission by user Rune featuring a working K-Drive mounted on a crewed vehicle, and another thread by Comrade Jenkins asking players to submit data on the Hell Kraken for use assembling a drive capable of quickly flinging the player's ship across the solar system at extreme velocity.