Deceleration Engines?

[stephensmat]

I'm currently putting together my first 'Large Interplanetary Craft'.

I'm sending up boosters, planning to dock them in a row. My question is this: When you transit to another planet, you have to slow down to enter orbit.

If I attach smaller engines to the 'front' end of the booster/Fuel Tank, can I then decelerate without having to 'flip' the entire spacecraft? Are there different controls I need to use?

[Streetwind]

Yes, you can do that, if you don't mind the extra mass. Your controls should not change as long as your control point (cockpit/probe core) does not change.

I recommend mapping your various engines to action groups so you can easily toggle them on and off as needed.

[king of nowhere]

9 hours ago, stephensmat said:

I'm currently putting together my first 'Large Interplanetary Craft'.

I'm sending up boosters, planning to dock them in a row. My question is this: When you transit to another planet, you have to slow down to enter orbit.

If I attach smaller engines to the 'front' end of the booster/Fuel Tank, can I then decelerate without having to 'flip' the entire spacecraft?

yes, you can - but why would you want to do it?

Rotating the spacecraft with reaction wheels costs you absolutely nothing. Putting more engines in the front increases the mass of the ship. By a lot! Engines are heavy. Putting unnecessary engines like that is gonna deeply hurt your deltaV budget. And it would bring no gain.

To add insult to injury, having those engines in "front" would not remove the need to rotate the spacecraft, because the direction that your spacecraft will be facing when you eject from kerbin is not the direction you'll need to make the capture burn. You make the kerbin ejection burn, then you time warp to the target planet, and then you won't be aligned with whatever other planet you went to. You still have to rotate the spacecraft.

Finally, don't think you can get away with "smaller engines". Depending on your target planet and trajectory, you may well find that the capture burn is more expensive than the ejection burn. And having weak engines to do it will result in loss of efficiency.

[stephensmat]

9 hours ago, king of nowhere said:

yes, you can - but why would you want to do it?

Well, I'm new at this. All my landings have been single craft, jettisoning rockets and tanks as we go. I'm still learning the rules of space-only motherships. Some of my 'modules' have a real 'flex' problem when I boost them up into orbits. A huge ship I don't have to flip around feels more stable.  I can fly up landing struts, and I've successfully attached a few parts in EVA, but I'm still learning.

[DeadJohn]

3 hours ago, stephensmat said:

Some of my 'modules' have a real 'flex' problem

Read about "autostrut".

Autostruts strengthen ships without the clutter of manually placed struts. Go into game settings, turn on "advanced tweakables", then most of your parts will have an "autostrut" added to their right-click part windows.

[king of nowhere]

9 hours ago, DeadJohn said:

Read about "autostrut".

Autostruts strengthen ships without the clutter of manually placed struts. Go into game settings, turn on "advanced tweakables", then most of your parts will have an "autostrut" added to their right-click part windows.

actually, as of the latest version, autostrut seem to be malfunctioning. they are not helping with my own docking ports problems. they are not even placed across docking ports, ever. I discuss the autostrutting problems in detail in my nanocristalline diamond challenge report, parts 11 to 14. but long story short, ever since i switched to version 1.12 autostruts have never worked for improving stability of docked modules..

 

but to get back to the OP's problem, as I said, you still have to rotate the ship. for you see, perhaps you think of your trajectory as linear and so you think you'll have to revert direction, but actually you are orbiting a planet, that's orbiting a sun, and you burn your rockets at some point to leave the planet on a conical trajectory encountering another planet at another point, orbiting the sun in a different way.... good luck keeping track of directions.

but there is a small trick to still manage turning around with minimal wobbling: a quick time warp. when you time warp, rotational movement is stopped, and that includes most wobbling.

using larger docking ports also helps, though of course they are heavier. reverting to a previous version helps too, i am strongly considering it

 

anyway, you still have to turn the ship around the first time to make the ejection burn. if the ship can tolerate that without a RUD, then it can turn around and do the capture brake too

Edited April 28, 2022 by king of nowhere

[Lt_Duckweed]

On 4/28/2022 at 7:18 AM, king of nowhere said:

actually, as of the latest version, autostrut seem to be malfunctioning. they are not helping with my own docking ports problems. they are not even placed across docking ports, ever. I discuss the autostrutting problems in detail in my nanocristalline diamond challenge report, parts 11 to 14. but long story short, ever since i switched to version 1.12 autostruts have never worked for improving stability of docked modules..

Sounds like you are on 1.12.1 or 1.12.2

In those versions autostruts could not span across docking ports, thanks to unlocked rotatable ports technically being robotic parts.

In 1.12.3 docking ports are locked by default, and autostruts work as per normal.