Notable inaccuracies include the perfect reliability of equipment (equipment generally only fails with excessive force) and the lack of life-support consumables. Kerbals can survive indefinitely in space either in a capsule or a space suit.[25] This simplifies orbital rendezvous by making it practical to wait multiple orbits until a desirable alignment is reached. Also, Kerbals have extremely capable EVA suits with 600 m/s of Δv. This is 24 times the capability of NASA's manned maneuvering unit, sufficient to reach orbit from (or even land on, return to orbit from, and rendezvous with a spacecraft orbiting around) small moons,[30] and allows EVA transfer between markedly different orbits.
The celestial bodies in the Kerbal solar system are about 1/10 the radius of their real-universe equivalents yet have comparable surface gravity,[6] implying that they have unrealistically high densities. This change to scale makes many tasks considerably easier. For example, a surface to low-Kerbin-orbit launch requires a delta-v of about 4.5 km/s, compared to 9.5 km/s for a low-Earth-orbit launch. In particular, because of the game also having unrealistically efficient and flexible (in terms of speed and altitude) turbojet engines, this means it is much easier to make a single-stage-to-orbit vehicle using jet engines to accelerate a vehicle to orbital speed on only a small fraction of its mass in jet fuel, then give a tiny boost with rockets to reach orbit, whereas in real life, a highly efficient but powerful and lightweight scramjet would be necessary to do the same with several times the amount of fuel.
The game's aerodynamic model applies drag force to parts based on a "drag coefficient" multiplied by the part's mass (remaining mass for fuel tanks) multiplied by the air density at that altitude multiplied by the speed of the part multiplied by a constant. This results in conventionally aerodynamic designs being unaerodynamic, and most designs having unrealistic levels of drag (often by orders of magnitude for large needle-like rockets). This also means that nose cones actually add drag to a vessel. The relatively minor drag on the nose cone is added to the drag of the other parts. This drag also reduces the effects of steep reentry trajectories and high-speed flight by applying drag forces evenly distributed between the mass of the vessel (except for nose cones, which may go flying off of the front of the vessel, and parachutes, which may pull the back of it off). Lift is calculated in a similar manner and so some planes can have unrealistically far forward wings and not become aerodynamically unstable. Also, non-wing parts do not generate lift, meaning, for example, that re-entering space capsules are neutrally stable in all directions and free to rotate, whereas in reality, they are intended to point heat-shield-down. No re-entry shock heating has been implemented yet;[26] although an effect exists to show the flames generated by re-entry, it currently is harmless to the spacecraft itself. Also the re-entry effects like heating up and the decrease of velocity stops on parts that are separated from the main space vehicle during re-entry. This could be for example the service module.