Why should i use spaceplanes?

[Vegetal]

You know xebx, this forum is about KSP, not the real world. Nobody cares if spaceplane SSTOs don't exist.

[Frozen_Heart]

IMO the main reason to use spaceplanes is due to them being cheaper to orbit and back. You only lose the cost of the fuel.

[tseitsei]

Ok i am lacking precision : in real world :

SSTO spaceplanes don't exist

Spaceplanes were a big economical failure (you launch the payload and the carrierspaceplane at the same time + it needs high cost maintenance after recovery and it flies badly)

So claiming spaceplanes (ssto or not) are really more economic is just pure absurdity, but we keep on seeing this here and in other posts.

We can also find a lot of challenges that can be fun, but are nonsense in the end for most of them.

The thread is about 'should' and showing where absurdity/scifi is and where real science is, is a good way to answer imo.

Orbital velocity of low Earth orbit is ~8km/s. On low Kerbin orbit it is ~2km/s. You see the difference?

There are/have been real life planes that can go >mach3 just by using jet engines (https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Records). So if low Earth orbit had an orbital velocity of ~2km/s or just a little more than that spaceplane SSTO's would most likely be a thing since you could accelerate to (near) orbital velocity with air breathing efficient jet engines instead of rocket engines...

KSP is a GAME that takes place on KERBIN and KERBOL solar system. Not REAL LIFE that takes place on EARTH and our solar system. 8km/s is much much more than 2km/s... Please understand the difference

Edited September 21, 2015 by tseitsei
Language, please.

[Starwaster]

What is the benefit of spaceplanes in KSP?

You feel great the first time you get it to work and thats it.

It takes much more time to reach LKO.

It has got very limited payload.

And for the mechjebbers - you can´t use MJ to launch.

So why would i use spaceplanes?

Uhm MJ user here. I just used MJ to take my plane to orbit today.... Used an ascent profile of 30% (turn shape) for a shallow gradual ascent. That was with a powerful plane (OPT) with a near vertical ascent starting from the middle of the runway. For a less powerful plane, take it up to 20km either manually or with Spaceplane Guidance and then use the ascent AP. (switching from airbreathing mode as necessary)

[David104]

What is the benefit of spaceplanes in KSP?

You feel great the first time you get it to work and thats it.

It takes much more time to reach LKO.

It has got very limited payload.

And for the mechjebbers - you can´t use MJ to launch.

So why would i use spaceplanes?

Most of the advantages have already been said I guess.

I recently build a vessel which was a rocket as a transfer stage for Jool and a small SSTO as payload. Went to Lathye with it...that way I didnt had to carry that much fuel for a landing and return to orbit to dock for the journey home.

Unfortunately misscalculated the required delta-v for breaking at Kerbin by a lot. So its still orbiting the sun...gonna rescue it some time I guess.

[gavman420SSJ]

i like rockets. i find spaceplanes to be annoying in general. to each his own

[Nothalogh]

nuclear spaceplanes are extreme non-sense

Nonsense? Hardly.

Politically unfeasible due to oxygen thieves? Sure

[Enceos]

When you play with the Kerbal Construction Time mod, you are limited in time between rocket launches. Sometimes there's an urgent need to get something to orbit but your launchpad is under reconditioning. Spaceplanes come to aid in these situations. And you can have several in your hangar ready for launch anytime. Upon landing they can be recovered to hangar for refueling and payload refitting.

KCT is awesome. Without KCT flying spaceplanes is a gameplay preference. There's a famous youtuber Bob Fitch, who is a rocket guy down to his bones. There's a famous streamer EJ_SA who's a Shuttle guy more than anyone out there.

[GoSlash27]

Ok i am lacking precision : in real world :

SSTO spaceplanes don't exist

Spaceplanes were a big economical failure (you launch the payload and the carrierspaceplane at the same time + it needs high cost maintenance after recovery and it flies badly)

So claiming spaceplanes (ssto or not) are really more economic is just pure absurdity, but we keep on seeing this here and in other posts.

We can also find a lot of challenges that can be fun, but are nonsense in the end for most of them.

The thread is about 'should' and showing where absurdity/scifi is and where real science is, is a good way to answer imo.

xebx,

Same thing everyone else said. The question was "What is the benefit of spaceplanes in KSP". Not in real life, but in KSP.

In KSP, spaceplanes (or at least well- designed spaceplanes) are much more economical than rockets. They are also safer, more reliable, and have more divert options should something go wrong during the launch.

Best,

-Slashy

[Martinoss]

For me spaceplanes are the way to go in my career. Imagine you don't use the revert option and cannot quicksave. Everytime your launch goes wrong, you will lose almost all your funds. And with the amount of funds I get from a contract, the contract is no longer profitable if I blow up 2 or more spacecraft. For most mission, unless spacecraft have the same mass and shape, I have to build a different launcher and because I need to make sure the launcher succeeds, it is oversized. Image you have a spaceplane, which is always the same for every launch, you can count on it as long as you place the center of mass of your payload in the right position (in my case). This speeds up stuff tremendously and I almost never lose launches anymore. Also my launchers are mostly about half of my total cost. So using spaceplanes halves the costs for missions, and in my career money is not that easy to come by.

In real world, using the same plane over and over again would introduce a huge benefit as seen with aeroplanes nowadays. We accept crashes and fly everywhere and with everyone. A space plane would introduce this also, of course we first have to get to a viable space plane, and that is the hard part.

[Warzouz]

Well, I guess it depends whether you get your fun from engineering to get results or from results now.

Also, I'd love to see your simple stock ~450t-payload 10-minute-build rocket. (seriously, if you've got one!)

Here http://forum.kerbalspaceprogram.com/threads/123195

The 400T and 600T payload launchers were created from the 200 and 300T in less than 10 minutes. First test was successful. If I had the computer for, I could scale it up to whatever. 10 minutes per new variant.

- - - Updated - - -

Ok i am lacking precision : in real world :

SSTO spaceplanes don't exist

Spaceplanes were a big economical failure (you launch the payload and the carrierspaceplane at the same time + it needs high cost maintenance after recovery and it flies badly)

So claiming spaceplanes (ssto or not) are really more economic is just pure absurdity, but we keep on seeing this here and in other posts.

We can also find a lot of challenges that can be fun, but are nonsense in the end for most of them.

The thread is about 'should' and showing where absurdity/scifi is and where real science is, is a good way to answer imo.

Well, true, but that's no the point.

The OP asked why using space planes. Answer has been given many times :

Pros

- Lowest cost per ton to LKO

- Fun to fly

- Nicer look

Cons

- Not scalable (not heavy friendly)

- Harder to design (more parameters to handle)

- Longer ascent + flying back to KSC

- Needs higher piloting skills (not an issue after training)

As usual with KSP, there is no correct "way" to play. We play as we want and fix our own objectives (until multiplayer game comes in...)

- - - Updated - - -

For me spaceplanes are the way to go in my career. Imagine you don't use the revert option and cannot quicksave. Everytime your launch goes wrong, you will lose almost all your funds. And with the amount of funds I get from a contract, the contract is no longer profitable if I blow up 2 or more spacecraft. For most mission, unless spacecraft have the same mass and shape, I have to build a different launcher and because I need to make sure the launcher succeeds, it is oversized. Image you have a spaceplane, which is always the same for every launch, you can count on it as long as you place the center of mass of your payload in the right position (in my case). This speeds up stuff tremendously and I almost never lose launches anymore. Also my launchers are mostly about half of my total cost. So using spaceplanes halves the costs for missions, and in my career money is not that easy to come by.

In real world, using the same plane over and over again would introduce a huge benefit as seen with aeroplanes nowadays. We accept crashes and fly everywhere and with everyone. A space plane would introduce this also, of course we first have to get to a viable space plane, and that is the hard part.

You say that SSTO space planes are "more reliable" ?

That's not relevant. Relibility depends on you skill for building stuff and flying them. Building a space plane is much more demanding than a rocket (what ever if recoverable or single stage). It took me a very long time to create my SSTO spaceplane. It needed a lot of tries (but mayb ot as many as my Eve ascent vehicle).

I use recoverable SSTO rocket because they are cheap and easy to use. I don't loose launch because of the LKO stage once I mastered the 1.0 new aero. Using rockets you can also use pre-built stages (that I do very often) from 15tons to 600tons. They are alsi very reliable.

Edited September 22, 2015 by Warzouz

[Red Iron Crown]

For me spaceplanes are the way to go in my career. Imagine you don't use the revert option and cannot quicksave. Everytime your launch goes wrong, you will lose almost all your funds.

The tradeoff here is that you *have* to recover safely to be economically viable. Flub the reentry or landing (or even the ascent at certain points) and you lose the recovery money invested in the costly spaceplane. I guess it depends on player skill and experience, I have a much easier time putting a rocket in orbit on the first try than putting a spaceplane up and safely returning it on the first try.

For most mission, unless spacecraft have the same mass and shape, I have to build a different launcher and because I need to make sure the launcher succeeds, it is oversized. Image you have a spaceplane, which is always the same for every launch, you can count on it as long as you place the center of mass of your payload in the right position (in my case).

I don't get this part. I find it easier to switch payloads on a rocket than on a spaceplane, due to fewer size/shape restrictions and CoM issues. As long as it doesn't exceed the rocket's payload mass capability I can be fairly confident it will work (and similar restrictions apply to my planes).

In real world, using the same plane over and over again would introduce a huge benefit as seen with aeroplanes nowadays. We accept crashes and fly everywhere and with everyone. A space plane would introduce this also, of course we first have to get to a viable space plane, and that is the hard part.

That was the theory behind the space shuttle, didn't pan out so well. Real space is hard on equipment, and recertifying and testing for reuse has been as costly as new builds (or worse) so far. Maybe Skylon will go somewhere with reusability (doubtful) or SpaceX (more likely), time will tell.

[Val]

Here http://forum.kerbalspaceprogram.com/threads/123195

The 400T and 600T payload launchers were created from the 200 and 300T in less than 10 minutes. First test was successful. If I had the computer for, I could scale it up to whatever. 10 minutes per new variant.

I completely agree, that this is the state of things.

But I also think rocket and spaceplane building can be tricky to compare directly for a few reasons. (Some assumptions and generalizations)

• Most of us have built a lot more rockets than we have spaceplanes.
  
• We often start KSP with small suborbital rockets (voluntary or not) and scale-up overtime.
  
• With spaceplanes it is quite common to go directly for SSTOs, getting no experience from starting smaller.
  

I kind of think of this as trying to make the first rocket you ever build in KSP a Mun landing and return. How much time and how many attempts would that take to get right?

I wonder, if I keep on building just spaceplanes, as I've done since 1.0.4, would I get to a point, where I could throw a design together for any payload in 10 minutes or less?

I'm not sure... Spaceplanes are much more dependent on aerodynamics, than rockets. So maybe for that reason rockets will always be faster.

[Warzouz]

Val, I agree that some KSP players could scale up a space plane in 10 minutes, but that requires some skills !

I think it took me much more time to create my SSTO (used for passenger and LKO kerbal recovery) than to design my whole Cygnus rocket family (and only the recovery part was really delicate). Creating a SSTO rocket is even easier that a staged rocket : keep your TWR between 1.3 ant 1.6, pack some fuel up to 3200m/s (3400 if you want a very comfortable margin), add fins. You're good to go.

For space plane, you have much more things to care about, it's more complex : if a KSP player likes building stuff, SSTO space planes are much more rewarding than SSTO rockets (which are even less fun than stage rockets).

Edited September 22, 2015 by Warzouz

[jmp470]

In my current career play, I only use space planes. In the beginning it was extremely frustrating, but, now that I understand the design principles, I enjoy it a lot more. I would post pics of my designs, but, I have not figured out how to post them to the forum. (Every time I try to post a picture it only wants another internet page) my current design is 40-60 tons with 1 mainsail and 4 whipsaws. It is super fast and gets to orbit quickly. It carries a 6T lander on its back, and a crew carrier of 4. I use it for contracts and to launch to the Mun, thus far. I dropped the mainsail and added VTOL capabilities to it, this is my Kerbal science / sight seeing machine.

[GoSlash27]

In theory, yes. In practice, rockets can lift much larger payloads, regardless of player skill or the amount of design effort.

For example, a simple stock rocket that takes 10 minutes to build can lift ~450 tonnes to LKO. How long does it take to design a spaceplane to lift that much payload? And how large stock rocket one could build in that amount of time?

Jouni,

This isn't an advantage of rockets IMO. I use rockets to lift cargo exclusively, but that has more to do with bulk and scarcity of cargo missions rather than spaceplanes' inability to do them.

What really perplexes me is the idea that the ability to lift 450t to orbit is apparently an important criteria. What on Kerbin are you folks putting into orbit that weighs 450t??

It's like the old Jerry Seinfeld comment about razor disposal containers in airliner bathrooms; I can't imagine actually shaving in an airplane bathroom let alone shaving so much that I'm wearing out blades...

Best,

-Slashy

[Jouni]

What really perplexes me is the idea that the ability to lift 450t to orbit is apparently an important criteria. What on Kerbin are you folks putting into orbit that weighs 450t??

An Eve lander or a Jool-5 ship, for example. At least if you do something resembling a reasonable mission (e.g. 4-6 kerbals and a plenty of additional living space), instead of just trying to fulfill the bare minimum required by the (rather boring and uninspiring) game mechanics.

[jmp470]

Isn't it more efficient to assemble that sort of spaceship in orbit? That way you avoid the initial issues of Kerbin?

[GoSlash27]

Isn't it more efficient to assemble that sort of spaceship in orbit? That way you avoid the initial issues of Kerbin?

jmp470,

Yes.

I think this is the main difference between players who value spaceplanes and those that don't; the ones who are into efficiency and cost-effectiveness tend to use spaceplanes. The ones who aren't don't.

Which is fine. To each his own...

Best,

-Slashy

[Warzouz]

Isn't it more efficient to assemble that sort of spaceship in orbit? That way you avoid the initial issues of Kerbin?

Well, I think differenty

lifting 100 tons cost twice than lifting 50tons (well even lower in my calculations...) http://forum.kerbalspaceprogram.com/threads/123195

To assemble a ship in orbit, you need engines, docking rings, RCS tanks and RCS thrusters which add mass. In the end, you may not gain from assembling stuff in space. The only advantage is avoiding sending horribly wobbling payloads.

[Jouni]

Isn't it more efficient to assemble that sort of spaceship in orbit? That way you avoid the initial issues of Kerbin?

It depends on how you define efficiency. I'd say that doing multiple launches is less efficient, because it takes more time. Player time is the fundamental cost measure in KSP, as all other measures can be derived from it.

If we ignore time and efficiency, designing a large modular ship can be quite hard. Interplanetary ships with a low TWR can live with a lot of wobble, but Eve landers have to be solid. The other option is to launch the ship empty and then fill the tanks with smaller tankers, but that can get quite tedious. (I once built a giant interplanetary ship in the 6.4x Kerbol System and then launched over 30 tankers to fill it. I'll never do anything even remotely similar again.)

[GDJ]

Because spaceplanes are the most fun a freaked out tourist can have (and watching their facial expressions crack me up!), and it takes some real planning to have a spaceplane take off, get itself to a 500K orbit, and have fuel to come back down and fly powered back to KSC. You actually have to navigate the plane and plan your trip.

[GoSlash27]

It depends on how you define efficiency. I'd say that doing multiple launches is less efficient, because it takes more time. Player time is the fundamental cost measure in KSP, as all other measures can be derived from it.

If we ignore time and efficiency, designing a large modular ship can be quite hard. Interplanetary ships with a low TWR can live with a lot of wobble, but Eve landers have to be solid. The other option is to launch the ship empty and then fill the tanks with smaller tankers, but that can get quite tedious. (I once built a giant interplanetary ship in the 6.4x Kerbol System and then launched over 30 tankers to fill it. I'll never do anything even remotely similar again.)

Yup. This is another difference. Some people find the act of assembling infrastructure and missions in orbit tedious while others actually enjoy it.

If you're in the former group then you have no use for spaceplanes. If you're in the latter, then they're indispensable.

Again, to each his own.

Best,

-Slashy

[Hodo]

What is the benefit of spaceplanes in KSP?

You feel great the first time you get it to work and thats it.

It takes much more time to reach LKO.

It has got very limited payload.

And for the mechjebbers - you can´t use MJ to launch.

So why would i use spaceplanes?

The real reason for using a spaceplane SSTO design is quite simply cost.

It is cheaper and easier to operate a SSTO space plane then most non-SSTO craft. Now SSTO tail lander rockets or fully recoverable SSTO rockets are cheaper still.

But the biggest advantage is you can cut your operational overhead in career mode by large margins if you have a few dedicated SSTO lifters. I know when I was seriously working on my SSTO fleet, I had 4 SSTO space plane lifters. And those 4 could do anything and everything I needed including go to other orbital bodies and return.

[eddiew]

...I'd say that doing multiple launches is less efficient, because it takes more time. Player time is the fundamental cost measure in KSP, as all other measures can be derived from it...

There's an assumption there that something that happens later on in the player's game is going to be more fun than what is happening to the player right now. If that's the case, then you're right that players should always look for the absolute fastest way to get stuff into orbit, assemble big bases, fire off big rockets and... er... well... do... stuff...

Thing is, KSP doesn't have an ending. Even in career mode, it's a sandbox game and you make your own rules. There isn't a consistent point that all players are commonly working towards, and there is no competition or expected speed of "progression". Some people chase science and mod in a massive tech tree; others want a base on every planet; some want antimatter farms at blisteringly tight solar orbits; others just want to fly things within the simulation the game provides. All of these are valid ways to play a sandbox.

Player time is only a cost measure if you perceive that you're "getting through" the grind of design, build and launch phases to get to the better thing later. An alternative view is that the goal of playing is to fill as much of my hour as possible with the activities I most enjoy. I have no need and actively don't want to minimise the time taken to design and launch something, if I'm enjoying the design and launch process

2p from Zen and the Art of Spaceplane Maintenance

In response to the OP; same answer as to "Why should I go to Jool (which takes ages and costs loads) when I can get all the sciences from Mun+Minmus?" You would go to Jool because you enjoy doing so and prefer doing so over going to Mun+Minmus. If you don't enjoy doing so, then don't do go to Jool. Or fly spaceplanes