How do you launch from the ground straight to an interplanetary trajectory?

[Athen]

If the title wasn't clear, this is basically what I mean: 

When they do their hohmen transfer, they just do it as they launch. Even if this is just for the sake of the video, how would one go about doing something like this?

[Scarecrow]

In one word, timing.  Launch needs to take place when the transfer window is open.  I haven't watched the video, but for interplanetary travel to the outer planets, I would launch just after dusk, and for the inner planets just after dawn.

[bewing]

You have to launch onto the planet's orbital trajectory. In map mode, zoom out until you see the orbit path of the planet. When KSC is exactly underneath that line, launch straight up in orbit mode on your navball.

Edited March 13, 2019 by bewing

[Laie]

12 hours ago, Athen said:

how would one go about doing something like this?

Without advanced computing tools like kOS or krpc? Saveload, try, repeat until you succeed.

I'd start with a markup satellite in orbit that has a Duna transfer dialled in, select it as target, then try and make it so that my rocket flies off on a course that's about parallel to to the projected trajectory of the markup probe.

Transfer means that you have a certain velocity (direction & speed) at the moment you cross the SOI boundary. Problem is that you have no way of knowing whether you're on the right track, or how far off you are in which direction, until you take the time to put down a maneuver node. Flying parallel to to a markup track should get you close, though.

You don't have to leave the SOI at precisely the same point as the markup trajectory, but you should be going in the projected direction, and at the right speed. For the latter, you have to figure out the time interval between the markup maneuver and the projected SOI exit, then cut your engines when your time to SOI boundary is about the same -- give or take a little depending on how much further out you already are by the time you cut your engines.

With a few attempts, I guess it's possible to get the transfer mostly right, down to within 100m/s or so.

 

[TheTripleAce3]

Treat the planet as the center of a maneuver node, except you have a very tiny amount of radial velocity depending on time of day/latitude.

 

If going outwards, launch at morning, inwards in the afternoon.

[Kerbert]

I escaped the Sun’s gravity for the first time today!  I don’t know where it’s going! Hahaha

1st Stage: 20 - S3 14400 Tanks attached to 4 - Mammoth Engines & 8 Twin Boar Engines which drop off mid stage.

2nd Stage: 8 FL - T800 Tanks attached to 1 RE-15 Skipper Engine.

I used a lot of Strut Connectors to keep everything stable. Overkill probably, but it worked!

I launched at night when the Mun was up. I passed right next to the Mun and just kept going!

Anything out there or are all those stars just a pretty picture?

 

[Curveball Anders]

3 hours ago, Kerbert said:

I escaped the Sun’s gravity for the first time today!  I don’t know where it’s going! Hahaha

1st Stage: 20 - S3 14400 Tanks attached to 4 - Mammoth Engines & 8 Twin Boar Engines which drop off mid stage.

2nd Stage: 8 FL - T800 Tanks attached to 1 RE-15 Skipper Engine.

I used a lot of Strut Connectors to keep everything stable. Overkill probably, but it worked!

I launched at night when the Mun was up. I passed right next to the Mun and just kept going!

Anything out there or are all those stars just a pretty picture?

 

1. Kerbols SOI is infinite, so you can't leave it.

1b. With infinite fuel you can continue to move further out, but infinite is still infinite.

2. All the stars out there is just a pretty picture, called skybox.

Sorry.

 

[Laie]

6 hours ago, Curveball Anders said:

1. Kerbols SOI is infinite, so you can't leave it.

"Escape", in this case, means that you're flying away so fast that gravity will never pull you back. That's totally possible.