The Kerbal X is a stock ship available to all players. It is a reliable, all-around ship capable of reaching orbit fairly easily and thus, is a good way for new players which have issues building their own ships to make orbit.It's total mass is 131.62t and have 74 parts. One should be aware that the stock version have no SAS or ASAS on board and it is highly recommended to add one.It also has no RCS Fuel Tank nor RCS Port.
The first stage is comprised of three Rockomax X-200-32 fuel tank and a 'Mainsail'.Also, six liquid fuel booster are staged in a Asparagus design. It as aerodynamical surfaces and a strong structure. The first stage is easily capable of launching the second stage into a parabolic trajectory, with good horizontal speed at around 90km, thus making it easy for the second stage to make orbit.The full stage with all of his boosters has 2700kN of thrust, for a Thrust to weight ratio (TWR) of 20.51. The sole 'Mainsail and relative fuel tank has a TWR of 21.36 (the total mass of the Kerbal X at that time is 70.02u.
The second stage is a Mk3 capsule mounted of a parachute, and has half of a 3m tank plus a 'Poodle' Engine. As it also has landing legs and a ladder, and hinted by the menu screen were a similar ship is seen, one can deduce that the Kerbal X was intended to land on the Mün, but it is not possible using conventionnal and autonomous means as the Kerbal X doesn't have enough to come back to the mun, has it do have slightly enough fuel for landing.
The first stage's central engine and relative fuel tank has 3177m/s of Delta/v, not mentionning the radial ring of boosters which has approximatively 1003m/s.This sums up to about 4180m/s, just about enough to make orbit (4500), making the Kerbal X a suitable option for orbiting small payloads.These payloads, for a propre orbitation, with autonomous propulsion to achieve orbit (320m/s).Such payloads should be less than 16.7 to keep the standard configuration of the rocket.Still, if one would will be willing to use the Kerbal X first stage as a launcher, the max weight of this assembly would be 68.1u of mass, as this is the minimal weight for a 2.2 TWR, which is seen as the acceptable ratio of a rocket.Note that this in this situation, the first stage derived from the Kerbal X wouldn't have 4180m/s as the mass to carry is significantly bigger and as such wouldn't prove as efficient.
The second stage has 2494m/s Delta/v, and the total Delta/v is 6674.
The ability of the Kerbal X to reach orbit with a relatively small rocket (for a medium payload (16.7u)), is significant in his reliability as bigger rockets tends to be more prone to exploding randomly or being unsuited for space travel.The two-stage to orbit leaves no debris and would be economically healthly in an event of a in-game budget.
Interesting use of the Kerbal X, with added RCS and a docking port (+SAS), is a space station docker, allowing crew transfers or module delivery and docking as the ship has a good marge of additionnal weight it can carries.If placed properly, the RCS thrusters assures an easy docking and the low chance of failure justifies the uses of the Kerbal X as a crew transfer ship has the chance of seeing the crew being killed near zero.
Another uses of the Kerbal X would be to land on the moon, with added basic functionnalities such as RCS, SAS and docking port, it would be fairly easy to refuel the ship in Kerbin orbit, possibly with another Kerbal X, and fly it to the Mun, land and eventually come back, or at least, go back to Munar orbit.
If one would be willing to be upgrade the Kerbal X, adding a small intermediate stage that can almost finish orbit would be a big increase in performance as 12% of the fuel is used to finish orbit in optimal situation (accounting you used exactly 4500m/s to make orbit).Of course, one willing to use often the Kerbal X must absolutely add both RCS and SAS.
-Orbit(4500m/s) = true -Munar-Injection(910m/s) = true -Mun Landing(1000m/s) = true -Mun surface orbit(700m/s) = false -Mun orbit return = false -Minmus-Injection(1010m/s) = true -Minmus Landing(?m/s) = ? -Solar orbit injection(1400m/s) = true (Interplanetary travel = false)