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KSP2 would be a joke without reusable rockets, sorry


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I am excited to buy KSP2 because the trailer mentioned many awesome future technologies like metallic hydrogen and sure that would be nice for interplanetary travel, but I was concerned it did not mention reusable rockets.  Non-reusable rockets is like taking an airplane flight to go on vacation and when they land that airplane they throw it in the trash, imagine how expensive that is and how much of a joke it is compared to re-usability.  I am also concerned because partially reusable rockets already exist (the SpaceX falcon 9 reuses the first stage), so if KSP2 does not have reusable rockets then it is already out of date.  If SpaceX successfully develops the Starship, then they claim that the Starship production line could churn out two Starships per week at $5 million each with a fuel cost of $900,000 per launch, put those two together for a total launch cost $2 million per mission.  That means $2,000,000/220,000 lb payload = $9.09 per pound, I think to Earth orbit.

 

I mean KSP2 also has nuclear pulse propulsion, which is awesome, and so efficient it is probably technically a reusable rocket.  I would be interested if anyone could estimate the launch costs for that so we can compare it to Starship.

 

Here is SpaceX's current rocket the Falcon 9, which has a reusable first stage not second stage, greatly decreasing space launch costs ($62 million vs $165 million).

https://www.spacex.com/falcon9

"SpaceX advertises Falcon 9 rocket launches on its website with a $62 million price tag. The insurance rate on a Falcon 9 is about 4% currently, the underwriter said. That’s the same rate as competitors’ similarly-capable rockets, such as the European launcher Arianespace’s Ariane 5 or U.S. rocket builder United Launch Alliance’s (ULA) Atlas V. But Ariane 5 and Atlas V launches go for upwards of $165 million each, meaning a Falcon 9 premium is about $2.5 million while its competitors’ premiums would be in the range of $7 million."

https://www.cnbc.com/2020/04/16/elon-musk-spacex-falcon-9-rocket-over-a-million-dollars-less-to-insure.html

 

But SpaceX is currently developing a rocket called Starship, which aims to be fully reusable: a reusable first stage called the Super Heavy (used to get into Earth orbit, not necessary for getting into Moon or Mars orbit) and a second stage that is planned to be able to be refueled in Earth orbit by a second Starship to allow the first Starship to go to the Moon or Mars and with more refueling even beyond Mars.

"220,000 lb payload"

https://www.spacex.com/starship

https://www.engadget.com/2019-09-28-starship-refueling-spacex.html

 

"Elon Musk says he is “confident” moving to Mars will “one day” cost less than $500,000 and “maybe even” cost below $100,000."

https://www.cnbc.com/2019/02/11/elon-musk-how-much-it-will-cost-to-move-to-mars.html

 

No joke SpaceX believes the fully reusable Starship might make spaceflight so cheap that they want to build one Starship per week.

"SpaceX’s stretch goal is to build one to two Starships a week, this year, and to pare back construction costs to as low as $5 million each."

https://arstechnica.com/science/2020/03/inside-elon-musks-plan-to-build-one-starship-a-week-and-settle-mars/

SpaceX's Starship May Fly for Just $2 Million Per Mission, Elon Musk Says.  The big spaceship-rocket duo will use just $900,000 of fuel per launch.

https://www.space.com/spacex-starship-flight-passenger-cost-elon-musk.html

Edited by Hari Seldon
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1 hour ago, Hari Seldon said:

Thanks!  How hard is it to land the first stage back on Kerbin while the second stage is doing its thing?

Getting it back on the ground is fairly easy.  Getting it down in one piece on the other hand...  That is one of the game's challenges.

The current system doesn't give 'reusable' rockets etc as such.  It effectively refunds you a proportion the value of what you land.  So you can 'imagine' that if you launch another the same it could be the same one that has been checked and serviced.

In KSP1 when you jettison the first stage and continue to fly the remainder of the craft the first stage is uncontrollable so usually crashes.  Depending on your design it is possible to separate the first stage later in the flight, out of atmosphere for example, which can give you time to get the final stage in a stable orbit then switch to the first stage and fly it down.  Is it easy? No, not at all, and it's not in real life either, so far only Space X do it regularly with orbital final stages, and it took them a while to work out how, and then refine their techniques so they can do it reasonably reliably. 

There are mods (like Stage Recovery) that can 'simulate' the recovery of jettisoned stages, but I haven't used any so can't tell you how they work.  It is certainly possible that KSP2 could have a stock implementation of this type of functionality, but I haven't a clue if it is on the cards or not.

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Landing the booster is a mechanic. It's not like you'd play to a certain level, and then unlock the reusable craft.

But I'm betting you'll be able to unlock the booster engines, and find a way to land them for full refunds. Given what's going on in the world of spaceflight right now, there's no way KSP Developers haven't factored it in. I'd be willing to be it'd be a mechanic in the game: "Make three landings of your booster, and you'll unlock autopilot for it."

Mechjeb gets you three quarters of the way there already. If a modder can work it out, you can believe the developers will.

I'd love a SpaceX DLC. We've got the 'famous' missions already, this couldn't be any harder, surely?

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On 5/16/2020 at 4:13 PM, Hari Seldon said:

Thanks!  How hard is it to land the first stage back on Kerbin while the second stage is doing its thing?

Right now, hard.  You CAN'T control 2 stages at once, so you can't do an accurate SpaceX style mission in Stock (where the Upper Stage is burning at the same time the launch stage is landing, well over 23 km away).  You can still manage to recover all stages- if you refrain from using side-mounted boosters- like in the video above, but it forces a less efficient ascent trajectory...

To do it practically, you need Flight Manager for Reusable Stages (a mod).

It's a functionality that SHOULD be made Stock- at least in a DLC or cooperative patch with SpaceX someday- but I doubt the devs will ever do so.  There are more pressing needs if you ask me: like bigger stock Jet Engines, proper rover controls, and an auto-walk button! (Though right now, they're busy with whatever this new DLC is working with the ESA...)

With FMRS, by the way, I routinely land as many as 2.5 stages (side-boosters, sustainer, AND upper stages) on a single mission.  It makes reusability reasonably easy, without simply abstracting the whole process away like some reusability mods (which I find a bit cheat-y...)

Edited by Northstar1989
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On 5/16/2020 at 10:13 PM, Hari Seldon said:

Thanks!  How hard is it to land the first stage back on Kerbin while the second stage is doing its thing?

Do you not have KSP, and you are thinking of jumping into KSP2 when it comes out?

Generally speaking, rockets are reusable if you desire and build appropriately.

In practice, I would define 3 classes of launch vehicles.

Disposable: no provision is given for re-entry or safe landing. It gets you the most performance, but you lose the vehicle.

Recoverable: you can't really re-use it "in the field", but it can safely land back on Kerbin, and you get a refund for the parts you bring back. If you get it back to the runway or launchpad, its 100% of the cost of the parts.

These are generally the most common, because attaching another payload can be impractical in the field, refueling can be a pain, and solid rocket boosters cannot be refueled.

Recoverable launch vehicles really only work on kerbin without mods, as a vehicle to get to and from orbit if Duna or Eve (for instance) cannot be recovered (only craft landed on Kerbin can be recovered for funds), and there's no building that enables you to launch a new vehicle from there (unless you have such a mod)

Reusable: you can go to orbit, land refuel, go to orbit again, ad nauseum, in one continuous playthrough, with no scene changes like when you recover a rocket and go to the space plane hangar or vehicle assembly building to launch something new.

If properly designed, you can even take new crew and payloads to orbit without recovering the launch vehicle... You just need to drive out a fuel vehicle or run on board mining equipment long enough.

SSTOs are the most common method of doing a recoverable or reusable vehicle.

Since you can only control one craft at a time, reusable or recoverable 2 stage designs are harder to make.

I make them where the 1st stage goes suborbital, and the 2nd stage gets into a stable orbit fast enough that I can switch back to the 1st stage before its too late to save it.

Without mods, SSTOs are so easy that its not worth the hassle of a recoverable or reusable 2 stage design on Kerbin, but on Eve, 2 stage is the only way I have managed to make a practical reusable craft for getting to orbit and back.

 

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  • 4 weeks later...

StageRecovery and FMRS can both catch dropped stages outside of physics range as long as they have either a) enough parachutes to slow their descent (they need not be deployed or even armed, just attached to the stage somewhere) or b) enough fuel to at least simulate a powered landing. I use SR as it’s simple and plays nice with some other mods, and it is configurable to give more or less funds back depending on range from KSC, landing speed and can also be setup to ‘destroy’ stages that were going too fast without sufficient heat shielding.

As for doing it by flying your boosters yourself, it’s possible without any mods at all, but a lot more difficult. You almost certainly won’t be doing any Space-X style double landings by yourself, although in KSP2 that might work with multiplayer depending on how it’s set up.
It’s also a lot easier (and more realistic) to recover the booster then launch a ‘new’ one than it is to actually try and staple a new payload on top of the booster while it’s still parked in a field somewhere- even SpaceX have to collect the boosters up and give them a good checking over before integrating a new payload.

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On 5/16/2020 at 4:10 PM, Greenfire32 said:

You can build fully reusable rockets currently in KSP, it's just a matter of player investment, so I would say the same functionality will be present in KSP2 since nothing is being removed.

Without mods, the physics engine fights you every step of the way (in recovering rockets).  I pretty much burned out my original play of KSP due to excessive reuse, and quit for some time.

To reuse a booster there are two strategies:

1.  Use a low fuel/high thrust to get a bunch of delta-v, then return before you leave the physics bubble.  I found this next to impossible, but later the physics bubble increased and it might be possible.

2.  Have enough extra fuel so that the booster can "SSTO*" after detaching the upper stage.  I almost certainly used SRBs with this, but the center booster was valuable enough I wanted to recover it.  Loft both first and second stages high enough they don't get deleted by the physics engine.  Switch between the two rockets (don't count on "[" and "]" working, you'll have to mouse fast) and bring both to orbit.  Then return the booster to as close to KSC as you can (without breaking it).

At this point vanilla KSP is pushing you to a spaceplane that only works thanks to a lot of design choices based around rockets that KSP spaceplane engines easily break.  I strongly recommend mods if you want to deal with recovery, and would go so far to recommend "stage recovery" type mods if you ever feel recovery is getting tedious.

* Note this is much closer to saying "Falcon 9 boosters can SSTO" than what is normally meant by SSTO.  You are bringing zero payload to orbit, and just giving an otherwise empty shell the delta-v it needs for a minimal orbit (to keep the physics engine from deleting the thing and giving you the chance to land somewhat near KSC after going around the planet once).  You can presumably skip this if you are willing to land far, far East of KSC and getting your payload to orbit quickly enough.

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The only thing that you can't do easily in KSP1 (stock) right now is atmospheric stage recovery. This is a relatively minor limitation IMO though as the planets are scaled down. It's totally possible to make a fully recoverable spacecraft even for Eve – I've made a few – and it's quite easy for Kerbin. You just have to engineer them so that the first stage goes high enough that you can get the upper stage to orbit and switch back to it before it falls below the atmospheric deletion altitude.

SSTOs are pretty simple for Kerbin, even for quite heavy payloads, and those you can fly back yourself.

It would be nice if KSP2 removed this limitation, for example with automation, multiplayer, or a "time machine" that lets you fly the upper stages to orbit, then skip back in time to stage separation for each stage and fly those back down one by one. From where I'm standing this is squarely in the "nice to have" category though, by no means critical.

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On 6/20/2020 at 11:12 AM, wumpus said:

To reuse a booster there are two strategies:

1.  Use a low fuel/high thrust to get a bunch of delta-v, then return before you leave the physics bubble.  I found this next to impossible, but later the physics bubble increased and it might be possible.

2.  Have enough extra fuel so that the booster can "SSTO*" after detaching the upper stage.  I almost certainly used SRBs with this, but the center booster was valuable enough I wanted to recover it.  Loft both first and second stages high enough they don't get deleted by the physics engine.  Switch between the two rockets (don't count on "[" and "]" working, you'll have to mouse fast) and bring both to orbit.  Then return the booster to as close to KSC as you can (without breaking it).

That's the aforementioned "player investment" I referenced in my original post.

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