The magnitude or scalar absolute value of velocity is referred to as speed. So six 200 I sp engines still yields only 200 I sp.Velocity refers to a physical vector quantity which is described by both magnitude and direction.

When I sp is the same for all engines in a stage, then the I sp is equal to a single engine.

Xenon (max full/empty mass ratio = 4.167) Monopropellant (max full/empty mass ratio = 8.5) (These calculations use a full/empty fuel-tank mass ratio of 9 for all engines except those noted.) ISP(Vac) (s) No matter how much fuel you add you will never reach these ΔV without staging to shed mass or using the slingshot maneuver. Maximum Δv chart This chart is a quick guide to what engine to use for a single stage interplanetary ship. Use the atmospheric and vacuum thrust values for atmospheric and vacuum Δv, respectively. Fortunately for Jebediah, our dear Kerbals only have one brand of fuel to worry about.ĭelta-v (Δv) Basic calculation → See also: Tutorial:Advanced Rocket Designīasic calculation of a rocket's Δv. In real life, specific impulse is governed by things like combustion chamber pressure and propellant energy (hyrdogen/oxygen is more efficient than kerosene/oxgyen). The higher the specific impulse, the more efficient an engine is!

Specific impulse is used in important equations like THE ROCKET EQUATION (see next section) to determine how much oomph (or 'delta-vee') you can get out of a given amount of propellant. Most engines are designed for optimal performance either at Sea Level (the big ones that drive your first stage and boosters, which have lots of thrust!) or Vacuum (where they won't burn as much propellant, but can be VERY efficient).

Because this depends on the pressure of a rocket's surroundings, this can change between Sea Level and Vacuum (in space). Specific impulse measures the efficiency of a particular engine. Specific Impulse (I sp) → See also: Specific impulse Most rockets, straight off the launch pad, will utilize a TWR between 1.5 and 2.0. If TWR is significantly above, say, 2.0, your rocket will ZOOM! But it might ZOOM too hard for your poor Kerbalnauts.

You will need more engines, or perhaps MOAR BOOSTERZ! If TWR is less than one, then your rocket will not be going into space.

X plane 11 cheat sheet