Docking questions (no mods)

[GungaDin]

I'm working through career mode with no cheats or mods and I have a few docking questions:

(I've gotten ok with rendezvous and can get 2 spacecraft within a few meters at low speed.)

1 - The 'docking speed' display on the navball shows relative speed between the 2 ships but is there any way to distinguish between closing speed vs departing speed? Why doesn't the display go negative?

2 - I'm assuming that all docking ports are bisexual?

3 - What is a safe 'collision' speed?

4 - So far my spacecraft only have a single rear thruster - so for instance to slow down a bit I have to swing around 180 and hit the gas. Is it better or necessary to have smaller sub-thrusters mounted in order to line up 2 docking ports?

Thanks.

[Dave Kerbin]

1 - The 'docking speed' display on the navball shows relative speed between the 2 ships but is there any way to distinguish between closing speed vs departing speed? Why doesn't the display go negative?

If you look at the targeted object itself you'll see the distance overlaid on it. If the number is getting smaller you are closing, if it is getting bigger you are departing. Without mods there isn't much else to go on.

2 - I'm assuming that all docking ports are bisexual?

Yes, though they only work with ports of the same size. The regular sized docking port can dock with the shielded and the enclosed radial port since they are physically the same size, but the Jr. sized port can only dock with another Jr. and the same for the Sr.

3 - What is a safe 'collision' speed?

The heavier the spacecraft the slower you need to go in order for the kinetic energy to be overcome by the docking port magnets. Little capsules can come in at 5 m/s if you are experienced, while big loads should be less then 1 m/s. The velocity vector also counts - moving straight in you can go faster then if you are coming in from the side. With very light ships you can practically 'strafe' across the docking port from the side and the magnets will be able to hold you long enough for the docking clamps to engage. With heavier ships you need to get rid of as much side to side velocity a possible. Again it's all about the kinetic energy of the ship vs. the fixed magnetic force in the docking port trying to cancel it out.

4 - So far my spacecraft only have a single rear thruster - so for instance to slow down a bit I have to swing around 180 and hit the gas. Is it better or necessary to have smaller sub-thrusters mounted in order to line up 2 docking ports?

It is entirely possible to dock with only a single thruster, but it is considered an advanced technique (refered to as 'rcs-less docking'). The normal way to dock until you get really good at it is to use RCS thrusters - at least 4 - so that you can thrust forwards, backwards and in all directions laterally without changing orientation. Usually they are placed with respect to the ships center of mass, so that you can fire them to translate (move side to side) without also inducing rotation.

[blizzy78]

1 - The 'docking speed' display on the navball shows relative speed between the 2 ships but is there any way to distinguish between closing speed vs departing speed? Why doesn't the display go negative?

Never.

2 - I'm assuming that all docking ports are bisexual?

Uhh. Yes they are.

3 - What is a safe 'collision' speed?

0.2 m/s.

4 - So far my spacecraft only have a single rear thruster - so for instance to slow down a bit I have to swing around 180 and hit the gas. Is it better or necessary to have smaller sub-thrusters mounted in order to line up 2 docking ports?

It doesn't actually matter, because if you balance it out, the thrust vector should always go right through the center of mass.