What is the point of SSTOs?

[foamyesque]

Oh... actually, we do have one example of a SSTO in real life.

When people say SSTO in this context, they are talking about a. Earth and b. carrying a useful payload. There are rockets that can SSTO from Earth, but only unloaded.

[hyperformer]

While i do know that SSTOs are the most boss way of doing things, less fuel effiecient, who the **** cares about re-usability in sandboxmode, they are still the one thing i cant do in ksp, or at least right now.

[Spatzimaus]

I don't actually understand why you'd want a SSTO rocket for a launch platform

There are a few reasons.

1> Debris minimization; SSTO designs leave no expended bits floating in low orbit. Sure, the chances of a collision are tiny, but it's the principle of the thing. I haven't had a single bit of debris in orbit in years (in-game, that is). Yes, boosters that separate at low altitude leave no debris, but that brings us to the next point:

2> Less to go wrong. How many times has one of your engines been clipped away by a booster that tumbled badly at separation, or an ASAS that gets all wobbly when the separators fire? One of the most dangerous parts of any ascent (in-game or in the real world) is the moment when a new stage kicks in and the old one falls out of the way. A single-stage design simply doesn't have these issues; there's never any now-uncontrolled bits of debris that might damage your ship. Your RCS jets are always in the right spot for your current weight distribution, and you've got enough SAS and flaps.

3> Stability. We've all heard the KSP Mantra, "MOAR BOOSTERS! MOAR STRUTS!!!". Especially in the case of struts, larger designs become increasingly hard to keep stable. Try to launch an awkwardly shaped payload with an asparagus stack, and you'll see the problems; as the outer bits fall off, you lose the ability to use struts to stabilize the payload from the sides, and eventually are left only with a connection directly down (not the most stable configuration). But if you can make a large single-unit lifter, it becomes much easier to built it in a way that the payload is fully supported the whole way. My own SSTO heavy lifter, the Bucket, is shaped like its namesake for exactly this reason; payloads are held inside it, with struts connecting from all sides. Alternately, you can use things like the KW Rocketry fairings to place a payload inside a nose cone, which'll be really handy once we get a better aerodynamics model.

We have no idea whether the eventual career mode will require an actual economy (as opposed to simply being an ever-increasing per-rocket cost cap), but there's a good chance that there'll be at least some motivation to not using a bunch of disposable bits on every design. And honestly, it's like most other things in this game: it's hard, so we do it to see if we can, and then we can brag about it afterwards.

who the **** cares about re-usability in sandboxmode, they are still the one thing i cant do in ksp, or at least right now.

Then why don't you practice? Seriously, part of the reason people go on and on about SSTOs is that in the course of the many, MANY failed attempts, you'll learn things. You'll learn how aerodynamics works, you'll learn to use a lot more fine control over your throttle and angles, and you'll learn how to build efficient, small designs instead of always going for the biggest possible boosters. At first it seems insurmountable; you can take the stock spaceplanes and still not get to orbit. Then, once you succeed at those, you'll try to tweak those designs (or ones you see on these boards) to do it with "your" design, and fail miserably. You'll tweak, and tweak some more, and get progressively closer; instead of failing miserably at takeoff, you'll now come SO close to reaching orbit, or you'll escape but not have enough to circularize, or you'll have enough to circularize but not to come back down. Eventually, you'll succeed, and in the process you'll know more about how these systems work than we could ever teach you on these boards. (Seriously, go read a few threads on SSTO design, and you see this exact progression among the newer players.) At that point, your tweaked design will be unrecognizable from the craft that inspired it, and you'll keep tweaking again to make it easier to reach orbit (or have a better payload capacity, or have better efficiency once you're in orbit). After another month or so, you'll have designs that are so fine-tuned that you can go to Laythe and back with only one quick fuel stop.

But remember, we're in an alpha state still. It's not like you can set up your grand empire yet, spanning the entire star system, since we don't have the tools for that yet. Even if you could, none of this will be permanent, as at least one of the updates in the near future will invalidate old savegames. (Probably the next one, with the new resource system.) So all you can really accomplish right now is the development of DESIGNS (a working SSTO plane, a good fuel depot, an easily constructed station) and SKILLS (like how to get that SSTO into orbit). So what can you be doing in KSP right now that's more valuable, in the long term, than learning how to do these sorts of things?

[Tada]

I can see into the future - as they add funding into the game everybody will start flying SSTOs

[Temstar]

I can see into the future - as they add funding into the game everybody will start flying SSTOs

I rather doubt it, more likely everyone will be flying expandable "big dumb boosters" full of cheap components like SRBs and mainsails. Remember aside from abusing jets SSTO is always going to result in lower payload ratio. The amount of payload a single ELS can lift might require many trips by a SSTO. Even if we discount the cost required to service a SSTO after a mission to make it airworthy again (witness the astronomical cost for a shuttle service after a mission) that fuel is going to start to add up.

More simply, if SSTO is suppose to be cheaper than ELS, how come we have so many ELS in service and exactly zero SSTO?

[Tada]

Well, because we´re not as advanced and reckless as Kerbals

But well, lets see what will devs prepare for us.

I use SSTOs only for my Laythe surface to orbit operations - well just crew transfer in the moment, since we don´t have cargo bays

[Van Disaster]

The shuttle is a terrible example of a reusable spacecraft, and it's not even SSTO a spacecraft that can haul cargo to space and crew to do something with it is a handy thing to have sometimes - for building space stations, for instance - but a bit pointlessly complicated for just throwing satellites up. It does seem a bit strange that nobody has built a reusable basic launcher before now - NASA had the shuttle, the Russians are happy with old designs and had a funding crisis, and ESA I guess just lacks the initiative. There are other countries with space programs though...

I don't tend to launch anything over 100t so I don't really need massive launchers - I put 100t into orbit earlier with a two-stage launcher ( which was basically my 50t one with more fuel and bigger booster-stack engines ) which is one 3.5m KW main stack with two 3.5m KW liquid booster stacks set up ala Falcon Heavy. I could just rework the fuel pipes & make that a SSTO, but... it fits the flight profile far better as it is. KW ullage motors pull the side stages away quite happily even when it's tipped over the wrong way.

[numerobis]

I rather doubt it, more likely everyone will be flying expandable "big dumb boosters" full of cheap components like SRBs and mainsails. Remember aside from abusing jets SSTO is always going to result in lower payload ratio. The amount of payload a single ELS can lift might require many trips by a SSTO. Even if we discount the cost required to service a SSTO after a mission to make it airworthy again (witness the astronomical cost for a shuttle service after a mission) that fuel is going to start to add up.

I'm going to bet that the costs will be balanced such that big dumb boosters will be slightly more expensive than SSTOs, for game reasons: have the hard and sexy solution be prefered over the easy dumb solution. We'll have to see how changes to aerodynamics (including reentry heat damage) are implemented, and what that implies.

Both solutions may be beaten by a high-altitude launchpad à la Space Ship One.