Polar operations?

[strider3]

One issue I have when launching to return to orbit, to rendezvous with a polar orbiting craft, when landed on or near a pole, is...which way do I go? It sounds stupid but, after getting the lander on the ground, taking back off in the correct direction seems to "avoid" me? Is there some information I'm missing (I have KER) that would stop me from wasting fuel while waiting for the "thin blue line" to tell me how jacked up my direction is? Polar operations stump me and I'm sure I'm not using the KER tools correctly, to figure out which way to turn after launching. Equatorial is easy for me...polar is...

Edited November 7, 2019 by strider3

[VoidSquid]

As a general rule, when launching from any given latitude, the minimum inclination you can directly launch into is that of the latitude. So, if you launch from a pole, you'll always end with a polar orbit, if you launch from equator, you can launch into any inclination. That's why the US launches from Florida, not Alaska, Russia launches from Baikonur, not Moscow, ESA lauches from French Guiana, not France (mainland) or Germany. 
Launching from any non-equatorial latitude, to achieve an equatorial orbit, you'll need a second maneuver to change the inclination.

Edited November 8, 2019 by VoidSquid

[CBase]

The first thing you need to figure out: What is your problem ? Launching into 90° inclination or matching plane with your orbital redezvous (aka getting right LAN) ?

Both are way more tricky from polar. Lets talk about inclination and surface vs orbital speed first.

When you launch from equator rotation adds only to the length of your velocity vector, so switching orbital vs surface mainly affects how steep to ascend. At polar or high inclination launches rotation is sideways from your velocity and switching changes your inclination. Finally orbital speed defines your inclination, so do a gravity turn using orbital speed as direction from launch.

The second thing is matching longitude of ascending node (LAN) with your target. Or where to go to. If you are at the very north pole everything is south. Kompass are no big help. Mathematically (and in a simulation) you never are at the point, so directions are always well defined. Which is an illusion, because they move fast with small changes. Watch the target indicator as the target moves over you and you rotate with the surface. Unfortunately I can only advice to try and learn. Pick any direction for launch, check LAN difference after orbit and improve on next try. It massively depends on position and orbit which direction is really right.

[Fierce Wolf]

You should either launch and steer north or south. And how to determine which? In the map mode!

 

Check the destination orbit and see where is it pointing (that is, if it orbits "clockwise" or "anticlockwise" relative to your camera). Wait until the Space Center is right below the orbit path and launch. If the orbit "goes north" then burn north.

[bewing]

8 hours ago, strider3 said:

Is there some information I'm missing (I have KER) that would stop me from wasting fuel while waiting for the "thin blue line" to tell me how jacked up my direction is?

One thing that I find works fairly well is to use either target mode or KerbNet, but it takes a little planning. Sometime before you want to launch, you have to place a custom waypoint in the direction you want your thin blue line to go, or you need to have some landed craft that you can target.

Target mode is a little bit nicer because your target/waypoint is always going to be below your horizon, making it hard to see on your navball -- but at least you can always see the anti-target marker, and fly in the opposite heading to that. The problem with target mode, of course, is that your prograde marker is incorrect in target mode for getting to orbit/suborbit -- so you can't lock your SAS to prograde until after you have a thin blue line to work with and can turn off target mode.

But basically, you pop up off the ground vertically with maybe 50 or 70 m/s, rotate your nose to 45 degrees to the horizon (or better), then look at your navball quick to see just how much you need to rotate left or right to head toward your waypoint/target -- then head for orbit or suborbit. When your thin blue line stretches out, it will be pointing in almost the right direction, and then you can tweak things left or right.

 

Edited November 7, 2019 by bewing

[strider3]

8 hours ago, bewing said:

Sometime before you want to launch, you have to place a custom waypoint in the direction you want your thin blue line to go, or you need to have some landed craft that you can target.

How do you place a waypoint anywhere...when still landed?

[bewing]

15 minutes ago, strider3 said:

How do you place a waypoint anywhere...when still landed?

That's why it takes planning ahead of time. You have to do it from orbit before you land, or from another craft in orbit. (Placing a custom waypoint is a KerbNet feature, if you are unfamiliar with that.)

 

 

Edited November 7, 2019 by bewing

[strider3]

7 minutes ago, bewing said:

That's why it takes planning ahead of time. You have to do it from orbit before you land, or from another craft in orbit. (Placing a custom waypoint is a KerbNet feature, if you are unfamiliar with that.

I always get confused on KerbNet vs. CommNet. Whichever one requires you to have communication (relays, etc.) to remotely control a craft is turned off in my current career. Can ScanSat mod perform the same function?

Edited November 7, 2019 by strider3

[bewing]

1 hour ago, strider3 said:

I always get confused on KerbNet vs. CommNet. Whichever one requires you to have communication (relays, etc.) to remotely control a craft is turned off in my current career. Can ScanSat mod perform the same function?

Having communication to remotely control craft is part of CommNet. I've never tried ScanSat, but I doubt it can create custom waypoints.

To use KerbNet, you have to have a probe core on your craft. Open the menu for the core. It will have a button "Access KerbNet". It brings up a window of the terrain you are flying over, with a reticle. Click to place the reticle on the window, type a name into the Waypoint Name window, and click the "Waypoint" button to set a custom waypoint.

[strider3]

5 minutes ago, bewing said:

Having communication to remotely control craft is part of CommNet. I've never tried ScanSat, but I doubt it can create custom waypoints.

To use KerbNet, you have to have a probe core on your craft. Open the menu for the core. It will have a button "Access KerbNet". It brings up a window of the terrain you are flying over, with a reticle. Click to place the reticle on the window, type a name into the Waypoint Name window, and click the "Waypoint" button to set a custom waypoint.

Sweet, I'm launching the upgraded rescue lander from Kerbin now. I'll let you know how it goes. Thanks buddy!

[Superfluous J]

2 hours ago, strider3 said:

How do you place a waypoint anywhere...when still landed?

If you don't mind modding your game you can place waypoints in map mode even while landed with Waypoint Manager.

You can also see those waypoints in flight so you don't even need to target anything. you will be able to see the waypoint on your screen as you launch.

That said, I always just target the orbiting craft and launch in the direction it is, or if it's not passed overhead yet I launch away from its current position.

[Snark]

Numerous posts have been removed, due to getting into off-topic bickering, arguing about arguing, and politics...

...prompted by (I can't believe I'm actually having to type this) latitude, of all things.

C'mon, people, you know better than this.  We're all friends here, and we're having a friendly discussion about orbital mechanics and the effects of launch latitude on orbital paths.  That's what people are talking about, that's the topic under discussion, and it is off-topic to get into bickering about political boundaries and nit-picking over terminology, when it's perfectly obvious what people are actually talking about (and it's completely non-political).

So, kindly keep things on topic, and don't go looking to nit-pick and trying to pick fights.  I'm sure we can all comport ourselves like civil adults.

Thank you for your understanding.

[strider3]

On 11/7/2019 at 5:14 PM, 5thHorseman said:

If you don't mind modding your game you can place waypoints in map mode even while landed with Waypoint Manager.

You can also see those waypoints in flight so you don't even need to target anything. you will be able to see the waypoint on your screen as you launch.

That said, I always just target the orbiting craft and launch in the direction it is, or if it's not passed overhead yet I launch away from its current position.

That's what I did...waited until it was overhead and launched and then "followed" it until I got a good handle on bearing and inclination...

[snip]

So...got it done. It took a dozen attempts, tweaking the landing path a bit every time, until I "lucked" onto a relatively flat spot but, Sigton is home safe!

Edited November 11, 2019 by Snark
Redacted by moderator