Autopilot and HUD questions

[Ijon Tichy]

There I am, practising and starting to feel right at home in the Earth-Moon system. Most gripping game since Elite A few questions still nag me:

Whenever I make an orbital course correction, I use the autopilot to align me with the cardinal directions. During the burn I keep the autopilot engaged, figuring this will improve precision. But is the actually correct procedure? Or should I disengage the autopilot before applying thrust?

Concerning the HUD: in both surface and orbit mode, the velocity vector marker is the circled plus symbol for your positive direction and the plus symbol for the negative direction. In docking mode, the symbols are interchanged. Is there a deeper reason for this or is it just an inconsistency in the user interface?

Thanks for listening!

 

[Rathelm]

A pure prograde burn depends on what MFD you're using. I personally like TransX and most of the time I don't want to do a pure prograde burn. I'm sure NASA sets it up so all they do is prograde since it's more fuel efficient.

I believe that the reason the docking symbol uses the "cross in the ball" for slowing down is because it is more important for docking. As other tutorials have mentioned you want to get as close as possible to the station and then slow you're relative velocity to zero then actually make your burn toward the object. It's not the most fuel efficient, but until someone comes out with a more complicated and accurate docking MFD it will have to do.

 

[Hielor]

Whenever I make an orbital course correction, I use the autopilot to align me with the cardinal directions. During the burn I keep the autopilot engaged, figuring this will improve precision. But is the actually correct procedure? Or should I disengage the autopilot before applying thrust?

Yes, this is the correct procedure. The autopilot will keep you pointed along the cardinal direction during the burn. This is particularly important for normal/antinormal burns, since the "target" will be moving.

A pure prograde burn depends on what MFD you're using. I personally like TransX and most of the time I don't want to do a pure prograde burn. I'm sure NASA sets it up so all they do is prograde since it's more fuel efficient.

Prograde is always the same direction. And it's actually more efficient to combine burns than it is to burn just prograde, if the burn times coincide.

 

[Ijon Tichy]

Yes, this is the correct procedure. The autopilot will keep you pointed along the cardinal direction during the burn. This is particularly important for normal/antinormal burns, since the "target" will be moving.

Thanks for confirming that.

 

[Rathelm]

Prograde is always the same direction. And it's actually more efficient to combine burns than it is to burn just prograde, if the burn times coincide.

Yes, but wouldn't you ideally want to burn just in the direction you're traveling as opposed to having to put in a course correction during the burn? I mean I understand small course corrections are necessary, but wouldn't you want to put yourself in an orbit that just allows a pure prograde burn to get to your destination?

 

[Tommy]

The "plus sign in a ball" velocity marker is a positive velocity value. When Docking, it shows the direction for positive relative velocity which is away from the target (so the RVel gets higher in a "positive" direction. Approaching the target is a "negative" RVel since the distance is being reduced. Hope that helps explain it a bit - it's not intuitive.