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Thread: How to enable/disable engines???

  1. #1
    Rocketry Enthusiast
    Join Date
    May 2013
    Shanghai, China

    How to enable/disable engines???

    Hi there,

    after launching this little spaceplane into suborbit (carried by a large aircraft at launch, much like SpaceShipTwo), and safely returning Raysel Kerman to Kerbin, I would like to further explore the field of spaceplanes and SSTO's (picture of my spaceplane after landing):

    I already have a design in mind, but I have a question regarding controlling the plane: Can you manually enable/disable engines during flight, and if so, how do I do that? I'm asking because I will use turbojet engines as main propulsion until the atmosphere gets unsuitable. Then, I would like to switch to rocket engines (one of the 215 kN ones, plus two LV-N's) for orbit insertion and manoeuvring.

    The craft's ultimate goal will be to dock with a space station in Kerbin Orbit, or a large interplanetary ship for Laythe, etc... missions. The SSTO will be transporting and returning Kerbonauts.

    Any help is highly appreciated!


  2. #2
    Yes, either right click them in flight or assign the enable/disable/toggle actions to the action groups of your choice in the editor.

  3. #3
    Action groups are definitely the way to go for something like this, where you'll have multiple engines to turn on/off very quickly. They allow you to do it with a single keystroke.

    In case you're not familiar with them, in the VAB or SPH, there are two bright blue buttons in the top center of the screen. One allows you to adjust the parts in the vessel (and is active by default) and the other allows you to set up action groups. Click the action group button, choose the action group you want to modify (group 1, for instance) and then click on the part you'd like to add to the action group. It will give you a list of options, and here you would probably want to choose Toggle Engine. Generally speaking, toggle is a better option than Activate or Shut Down because it gives you more options, and if you accidentally fat finger the key too early, for instance, you won't have to fool around with manually resetting everything or wind up having to scrub the flight.

    There are some quirks with symmetry. If you've got two symmetrically placed engines, putting one of them in an action group will automatically include its twin. However, if you then remove the engine from the vessel and put it back on (like if you adjust the position of the wing that it is placed on), that will break the symmetry and only one of the two engines will be part of the action group. Unfortunately the interface doesn't show that this has happened, so you actually have to remove the engine from the action group and then put it back into the action group to get it working right. To make life more fun, occasionally the game will keep the symmetry and not remove the twin from the action group. In any case, it's easy enough to get around this, just set up your action groups as the last thing you do before leaving the SPH/VAB.

    For space planes I like to have an action group to toggle my jets, an action group to toggle my rockets, and a third to toggle my air intakes. Other people prefer a single action group that will simultaneously shut down jets and close intakes and activate rockets. The former allows more freedom - you can have rockets going at the same time you have jets going, for instance, in order to get the last bit of thrust from your jets, or you can shut your intakes but leave your jets active to drain excess liquid fuel and lighten the load on the rocket a bit. The latter is more convenient, especially if you're still shaky on piloting skills.

    ETA: I forgot to mention that if you do set up action group 1, you use it by pressing the 1 key on the keyboard by default. Action group 2 = 2, etc.
    Last edited by Jason Patterson; 18th May 2013 at 19:34. Reason: grammar are my friend

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