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How to launch a SpaceX type mission


Zamolxes77

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Lately I was toying with the idea of launching a SpaceX type mission. I seen several videos in which people seem to launch them successfully, but for some reasons I'm unable to replicate them. I'm using 1.2.

Is there some sort of mod that I have to use to allow for 2 objects to be tracked at the same time? Every time I separate my booster stage, I put the Payload on cruise speed, then switch to booster using the brackets and land it, but by the time I recover it, my payload simply ... disappears?

Or is there some sort of trick on how you switch between the two stages after separation ?

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Moving to Gameplay Questions.

26 minutes ago, Zamolxes77 said:

Lately I was toying with the idea of launching a SpaceX type mission. I seen several videos in which people seem to launch them successfully, but for some reasons I'm unable to replicate them. I'm using 1.2.

Is there some sort of mod that I have to use to allow for 2 objects to be tracked at the same time? Every time I separate my booster stage, I put the Payload on cruise speed, then switch to booster using the brackets and land it, but by the time I recover it, my payload simply ... disappears?

You're running up against a fundamental limitation of the game.  When a ship goes outside the "physics bubble" (~2.3 km in vacuum, ~20ish km in atmosphere), it's unloaded and goes "on rails" (stops all physical simulation, just travels in a ballistic path)... and when an on-rails ship drops too low in atmosphere (defined as 1% of Kerbin sea-level pressure, which corresponds to an altitude of around 23km on Kerbin), then it's destroyed and just vanishes.

In short, in the stock game, anything which simultaneously satisfies all of the below criteria is going to vanish without a trace:

  1. Is flying through atmosphere
  2. Is more than ~20km from the ship you're currently controlling
  3. Is below an altitude of 23km on Kerbin (the altitude limit would be different on other planets with atmosphere)

To work around this, either you need to have some sort of mod to help with that (such as Stage Recovery; I'm sure other folks can name others), or else you need to arrange your mission profile such that there's never any object that you care about which is simultaneously satisfying all of the above criteria.  Either it needs to land before it gets more than 20 km away from your current ship, or you need to switch to it before it falls below 23km altitude.

For example, here's a two-stage to orbit mission profile that can recover both stages in stock:

  1. launch
  2. stage 1 burns out while above 23 km and rapidly climbing
  3. fly stage 2 to orbit
  4. switch back to stage 1 before it falls below 23 km
  5. land it

Or,

  1. launch
  2. stage 1 burns out while above 23 km and rapidly climbing
  3. burn stage 2 to boost it to a high Ap that will take a while to get to
  4. switch back to stage 1 before it falls below 23 km
  5. land it
  6. switch back to stage 2 before it reaches Ap, and then circularize at the appropriate time
26 minutes ago, Zamolxes77 said:

Or is there some sort of trick on how you switch between the two stages after separation ?

You can switch between two craft that are inside the physics bubble (2.3 km of each other) via the [ and ] keys by default.

If they're farther apart, you can switch by going to map view, clicking on the icon for the ship you want to switch to, and choosing the "switch" button that pops up.

Note that there are some situations (such as flying through atmosphere) where the game won't let you switch, and will print a message to that effect if you try.

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You can do the 2nd type of profile and recover 100% with a little thinking. I've recovered 1st stages on the landmass east of the KSC successfully using that method. It's a parachute landing but it's recovered.

Burn 1st stage and leave a few percent fuel in it.

Separate and burn the 1st stage retrograde, switch to 2nd stage, burn to AP.

Now you have your 1st stage landing prior to 2nd reaching AP (usually).

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20 hours ago, Raideur Ng said:

You can do the 2nd type of profile and recover 100% with a little thinking. I've recovered 1st stages on the landmass east of the KSC successfully using that method. It's a parachute landing but it's recovered.

Burn 1st stage and leave a few percent fuel in it.

Separate and burn the 1st stage retrograde, switch to 2nd stage, burn to AP.

Now you have your 1st stage landing prior to 2nd reaching AP (usually).

I use a similar method, since Career was basically introduced. My method involves sending the whole craft into orbit, separating there, then land the ascent stage to KSC for 100% refund. Landing it on next continent is out of the question, at least for me.

I'm trying to get as close as possible to a Space X launch, although I realize might not work, considering they actually land on barges at sea. Scott Manley had a recent episode he actually did land on a barge at sea.

It seems like in vanilla game, is not possible only if I perform extremely inefficient burn maneuvers, as exemplified by Snark. I did multiple tests and I haven't even managed to land the booster stage at KSC without crashing, yet - over 20 tries. I either run out of fuel 100 meters above ground or thing becomes unstable. It also seems to cost a lot of fuel, nearly 20% of total booster stage capacity, to reverse orbit and land at KSC, which makes the whole thing very inefficient, which is the thing I'm after. Seems like I need some modded engines, or to rethink the configuration on the booster, instead of 2 vectors that I use, use many Swivels perhaps in a cluster array.

Well thank you both for your input, the search continues.

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 It can be done without mods. You just have to fly very, steep inefeecient launch trajcetories that takes the first stage up past 80 or so KM. Seperate, then while the first stage coasts to apoapsis you burn the second stage down range as far as possible. Get it out far enough to where you have a good few minutes before the second stage hits apo. Switch back to the first stage booster, perform the boostback, then either stick with it and land it, or switch back to the second stage to burn further out. Ive seen people able to do perform a FaclonHeavy profile successfully like this.   However i dont do this. I dont like the very steep, unrealistic trajectory. I use BDArmory. I strip the mod of all its weapons and only use the plugin which gives you the option to chance the load distance to 100km ( max ) at will. And it works very well. 

 

I hammed it up a little in this video, but it shows the process very well.

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