Using the navball with a landed target

[OHara]

There is an old bug, beautifully described on the tracker, about how the rotation of the planet is sometimes wrongly left out of the velocity of a landed target, for purposes of the nav-ball indicators when in 'target' mode. There is a very nice video https://youtu.be/VU-_InTkc54?t=681 warning new players about this, for aircraft landing.   It also affects targeting bases on other bodies, whenever the body has noticeable rotational velocity.

I get tired of manually switching the nav-ball back to 'surface' mode, and often think there must be a better way to avoid the bug.  Does anyone know a better way?

I can increase the physics loading distance for 'landed' objects, because the bug is avoided when the target is physics-loaded, but would not recommend that in general.  Better would be a way to prevent automatic switching of the nav-ball to 'target' mode, or at least delay the switch until we are in physics range.

[Alshain]

I'm not sure that is a bug.  Target mode isn't always used when targeting something on the planet.  If you factored in the rotation of the planet during a rendezvous in orbit, it would be incorrect.

I don't know of a way to avoid it.

[bewing]

I think the bug is best avoided if you set a waypoint using KerbNet, and then activate the waypoint, instead of ever using ground targets directly. The navball never switches into target mode for waypoints.

 

Edited March 27, 2017 by bewing

[OHara]

19 hours ago, bewing said:

I think the bug is best avoided if you set a waypoint using KerbNet, and then activate the waypoint, instead of ever using ground targets directly. 

Waypoints do seem a little more convenient for the KSP runway:
+ you avoid the 175m/s offset in indicated airspeed, that appears 60km away when the navball switches to target mode
+ you can put them right on the runway, whereas flags or rovers need to be 30m or so away so they don't count as vessels on the runway
- but you need to have a probe core on the rover to set the waypoint

Directly targeting the base stil seems more convenient to land at bases on other bodies:
+ you get anti-target and retrograde markers, so you can aim a lander with its control-part oriented so the nav-ball points to the sky as usual
+ you get AN/DN markers that can help align your orbit to the base
- you just have to remember to set the nav-ball back to surface mode, when it switches to target mode 60km from the target

Interestingly, if we go within physics-loading distance to a landed target, which corrects the indicated velocity to the target, and then move away beyond the unloading distance, the velocity remains correct... until the next quicksave/quickload.   I couldn't make good use of this quirk, though.  
A module-manager patch to increase the physics-loading distance: 

Spoiler

@PHYSICSGLOBALS
{
    @VesselRanges {
        @landed {
            @load *= 5
            @unload *= 5
        }
}

 

[bewing]

7 minutes ago, OHara said:

- but you need to have a probe core on the rover to set the waypoint

You need to have a probe core on something at some distant time before you actually need the waypoint, to set the waypoint. But it doesn't have to be the rover. In fact, you can just launch a core with an antenna to the runway to do it, and then immediately recover it.

7 minutes ago, OHara said:

+ you get anti-target and retrograde markers, so you can aim a lander with its control-part oriented so the nav-ball points to the sky as usual
+ you get AN/DN markers that can help align your orbit to the base

You can use a waypoint until you are 60km from the target, and then switch to direct targeting, and get all these benefits for the last 60km.

 

Edited March 28, 2017 by bewing

[ForScience6686]

I've used ground targets with much success in the past.  Generally I just use it for runway approach.  But I have also used it for mining outposts, to land right next to the fuel depot, <50m.  What requires you to be so precise?