Voyager Chalenge

[Jack Slinger]

Hi guys and girls, I've been playing KSP for a few days now and I've orbited and escaped gravity, so now I've added a communication satellite mod and the mission is to get it to escape gravity and then return with your kerbonauts.

Rules:

- Have to launch a communications satellite into escape velocity

- Jeb has to touch the ground again safely

- no mods except the communications satellite can be used

This may have already been done but I couldn't find it

Here's my attempt (It didn't work :'():

[deltagear]

You may want to consider liquid engines for your final 2 stages, solid motors don't offer a lot of control when it comes to orbital adjustment.

[Warringer]

Where's the satellite mod?

[Finrandojin]

Where's the satellite mod?

http://mod.gib.me/kerbal/mods/Dirty/commsat.zip

Also, I'm the guy in the other thread who managed to carry the thing to orbit(apogee 158, perigee 137 km) and landed safely. I must say getting it to escape velocity will be a grand challenge, one that I accept gladly in the name of advancing the science of all of Kerbal!!!

[Warringer]

[shameless plug]

And with my KSP Orbital Calculator you can get the escape velocity for any given height.

[/shamless plug]

At least I hope that the escape velocity calculation is implemented correctly...

[EmperorJon]

Hah, was reading this and was like 'Hey this is what Jack was talking to me ab- oh...'

Good luck mate, I tried it too. Got the satellite to escape velocity, punched it off, and didn't have enough fuel to get back. ¬¬

[Finrandojin]

I succesfully hauled the scientific payload to a Kerbala Departure Trajectory, now only time will tell if my single tank/engine combo can arrest my orbital velocity enough for safe re-entry.

I will be posting a video along with the .craft file if I'm succesfull.

[edit] got the guys back safely! Was a close thing I thought I might come down on the dark side.

the .craft file for my ship, the third iteration that did the trick (requires the satcom mod from http://mod.gib.me/kerbal/mods/Dirty/commsat.zip)

http://www./?f8wax0jx3ydd37b

youtube video of launch and probe release:

[Jack Slinger]

Nice One!

I never thought of slingshoting around Kerbal. I'm not challenging the fact you did it that is obvious, but I use V^2 = 2GM/r to calculate escape velocity and I think that only works straight up so how did you work out what escape velocity was.

Oh and by the way If you have an explanation about how slingshoting works hidden up your sleeve I'll take that as well. ;P

[Finrandojin]

how did you work out what escape velocity was.

Oh and by the way If you have an explanation about how slingshoting works hidden up your sleeve I'll take that as well. ;P

it's very simple, the escape velocity of Kearth from the surface is around 3500 m/s as long as you are going atleast that fast, in any direction from Kearth, you will be on an escape trajectory, now about my flight profile. If I were to fly straight up for the entire flight I would be fighting Kearths gravity every kilometer of the way, by instead thrusting laterally once outside the atmosphere I can gain more velocity as I'm thrusting perpendicularly to the pull of gravity, and so I can save a ton of fuel. Bottom line, going straight up is the least optimal way of achieving escape velocity.

[Jack Slinger]

The force due to gravity is GMm/r^2 If you go straight up your decreasing r the most and thus decreasing the force of gravity. If you go at a 45 degree angle say then r is not decreasing as rapidly so (I think) you'd need to be going faster.

P.S. I have I feeling what I just said is total nonsense but I can't see where

[Finrandojin]

The force due to gravity is GMm/r^2 If you go straight up your decreasing r the most and thus decreasing the force of gravity. If you go at a 45 degree angle say then r is not decreasing as rapidly so (I think) you'd need to be going faster.

if you're going straight up the force that gravity has on you is the opposite of where you are thrusting, in essence there are two vectors and gravity is simply substracted from your acceleration. Now imagine that the angle is 90 degrees, since your acceleration is perpendicular to the force of gravity you will not lose acceleration because of it(quite the opposite actually).

[Jack Slinger]

I see at 90 degrees there would still be a downwards force from gravity but If you thrusted fast enough you could escape. Is the escape velocity the same regardless of angle then?

[Spacew00t]

I succesfully hauled the scientific payload to a Kerbala Departure Trajectory, now only time will tell if my single tank/engine combo can arrest my orbital velocity enough for safe re-entry.

I will be posting a video along with the .craft file if I'm succesfull.

[edit] got the guys back safely! Was a close thing I thought I might come down on the dark side.

the .craft file for my ship, the third iteration that did the trick (requires the satcom mod from http://mod.gib.me/kerbal/mods/Dirty/commsat.zip)

http://www./?f8wax0jx3ydd37b

youtube video of launch and probe release:

I'm going to be honest here, I don't understand how you got back to the ground safely. Your vertical speed is way too high and you don't have any fuel left.

[EmperorJon]

He's well under escape velocity, I think, so it'll just go up and up until he stops and then falls. You can clearly see his velocity is going down at the end, and his height is going up. So he will eventually stop.

[Finrandojin]

He's well under escape velocity, I think, so it'll just go up and up until he stops and then falls. You can clearly see his velocity is going down at the end, and his height is going up. So he will eventually stop.

correct, after my retroburn I was on a highly elliptical orbit and luckily my perigee was in the atmosphere so I landed safely.

[Spacew00t]

correct, after my retroburn I was on a highly elliptical orbit and luckily my perigee was in the atmosphere so I landed safely.

Hmm, how long did it take? I imagine it would have taken awhile to lose all that vertical speed.

[Finrandojin]

Hmm, how long did it take? I imagine it would have taken awhile to lose all that vertical speed.

Don't remember of the top of my head but it was about 20-30 minutes

[illectro]

I posted this video a few days ago demonstrating that going straight up is not the best way to achieve escape velocity, you want to burn as much fuel as possible at altitudes as low as possible.

The Voyager challenge is a bit harder than the real life launching of interplanetary probes because even when they launched them from the Shuttle (like Galileo) the spacecraft contained the upper stage to get it to escape velocity. The crew vehicle never achieves escape velocity. And even then the Galileo probe performed flypasts of the terrestrial planets to pick up extra gravitational speed boosts to get it to Jupiter.

[StrayEagle]

I succesfully hauled the scientific payload to a Kerbala Departure Trajectory, now only time will tell if my single tank/engine combo can arrest my orbital velocity enough for safe re-entry.

I will be posting a video along with the .craft file if I'm succesfull.

[edit] got the guys back safely! Was a close thing I thought I might come down on the dark side.

the .craft file for my ship, the third iteration that did the trick (requires the satcom mod from http://mod.gib.me/kerbal/mods/Dirty/commsat.zip)

http://www./?f8wax0jx3ydd37b

youtube video of launch and probe release:

Wow....you were way above escape velocity for your height, from my calculations, you could have released you satellite just after 8:12, and it would have escaped.

Orbital/escape velocity calculator: http://kerbalspaceprogram.com/forum/index.php?topic=562.msg5237

Also, you were lucky you made it back...lol.

Good work none the less. Its not easy to get that done

[Jack Slinger]

If you reach orbital velocity will you escape regarless of angle to the center of the planet?

e.g if you head straight up at escape velocity you'll escape but if you slant 45 degrees and then reach it will you still escape?

what about 90 degrees ect.

[dogthinker]

If you reach orbital velocity will you escape regarless of angle to the center of the planet?

No

e.g if you head straight up at escape velocity you'll escape but if you slant 45 degrees and then reach it will you still escape?

Yes, you will.

what about 90 degrees ect.

Yes, you will.

There's one angle where it's particularly likely to end badly. 180 degrees.

[DeCi]

No

Yes, you will.

Yes, you will.

There's one angle where it's particularly likely to end badly. 180 degrees.

On the contrary good sir thats when the fun starts!

[silent_prtoagonist]

Success! With a five-stage monstrosity that bears a striking resemblance to the Burj Kalifa It's actually quite a bit of overkill, I could probably put two or three satellites in an escape trajectory without sweating it. I had a smaller design that probably could have done it, but then I got one-more-stage-itis and this was the result.

Already at escape velocity and still a whole 'nother stage to burn

Payload sep

After return stage burn

...and finally fell victim to the dark side landing bug >