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Separating Booster Stages Gracefully I have seen this technique used in various craft designs, but I thought I would make an explicit post on separating booster stages, especially using FAR, with parts that tend to touch your spacecraft or each other during rotation away from the spacecraft while separating, due to aerodynamic effects. For booster stages, you generally don't need sepatrons to get your boosters away from the craft. In fact, in some designs they simply do not work the way you would expect due to aero drag overcoming their power, or due to parts clipping into each other and "sticking" to each other while rotating away from your main vessel (I tested this with full size Flea SRBs as separators and even they didn't work in FAR. the stickiness was too great). Take a tip from the Russians: mount your first stage boosters with a slight angle inwards: use the decoupler itself to rotate a few degrees inwards.. doing it with the tank alone will not work. When the boosters fall away, they will rotate around their center of mass, which is way down near the bottom of your boosters when the fuel tanks are empty. If you rotate them inwards a few degrees, a normal decoupler will provide enough force to rotate them away, and their rotation will never get near your spacecraft. You will lose a small amount of delta V, but in your first stage boosters, this likely doesn't amount to too much. For stages that are separated high up in the atmosphere, this isn't as much of a concern, and sepatrons will work just as you expect, but you can use this technique there as well to avoid the additional part count. This technique used in stock KSP will also help avoid your boosters impacting each other on the way down, if you would like to use a recovery mod to save cash. Basic Example of inwards rotation The example is not elegant, but it shows the principle. :-) This design is very simple, and is spec'd to cheaply take a full orange tank into orbit at 80km with 500+ m/s to spare (using FAR). It succeeds in stock KSP without the fairings with 1000 m/s to spare. This was intended at a Munar or Minmus orbital refueler. It has loads of RCS as well. To use it as a Munar/Minmus refueler in FAR, you can add a few solids to increase the delta V left after orbital insertion. Mainsails and Poodles for the entire thing. The shown craft game has FAR, StockBugFix and Procedural Fairings installed so that you can fire your rockets while they are protected by a boat-tail. If you don't have those mods installed, don't use fairings like this.. they will not work! The engines will not activate. POST NOTE: Yes, I do know there are other ways of achieving this (with different nose cones, etc) but this is one technique that I haven't seen getting much attention, and it has saved me a lot of hassle in early games! Also, in FAR, your boosters, if ejected in a low enough atmosphere with enough speed, will have a good chance of self destructing regardless of how you tweak it. To avoid that, you have to use more advanced nose cones, add back in sepatrons to keep the stage upright after separation, and use any other technique you can to keep them upright until they slow down enough not to get destroyed by aero forces. But they will still not touch your main spacecraft.