A question on the practicality of Space Shuttles

[More Boosters]

Hey,

So I've never actually bothered with *mostly recoverable* spacecraft or full blown SSTOs with rockets being so much more effective and simpler. However, I've also installed a few mods that ask rather high sums for the parts in the career mode, so it would seem I should start taking recovery more seriously to both save my money up and to recover the expensive engines and I would like to ask about the practically of this.

On average, what's the operating cost of a shuttle in percentage? How much of the starting sum do you never see again?

Should I just go with SSTOs? I've tried before but I could never build one, admittedly not having tried much, but there's also some charm in the Space Shuttle; after all however impractical was at times it's still one of the most iconic spacecraft and one of the first you learn about as a kid. Are such systems sensible in KSP? Maybe I could just take some of those oversized SRBs from the SpaceY mod and recover them with chutes and slap them on something with no other detachable parts?

Let me know about your ways to deal with recovery and efficient operation.

[Sharpy]

Go with SSTO rockets.

Spaceplanes are hard to fly, hard to land, and take excessive time for both. Never mind building one with non-token payload takes a lot of effort.

OTOH rockets like these take maybe five minutes to deorbit and land for recovery.

[The_Rocketeer]

Sensible isn't the word for the Space Shuttle.

However...

Rockets are like KSP on easy mode - easy to build, easy to fly, easy to land, easy easy easy.

Spaceplanes are KSP on hard mode - hard to engineer, harder to fly (if badly engineered), hardest to land (ask any pilot, landing safely is the hardest part of flying).

Spaceplanes do take longer in practically every respect, but they look *cool*. Compare Thunderbird 2 with Thunderbird 3 (we'll conveniently disregard that 2 wasn't a SP, and forget the ugliness that was 1) - no contest IMHO. They're also much more economical - again, if they have been well engineered AND well flown.

[Warzouz]

Well Space planes are quite fun to fly, they are efficient in mass ratio, and in price. But their main issue is that they aren't scalable. If a given SSTO is missing few tons to LKO, you can't simply add fuel, and engines. You'll often have to redisign it.

On the other hand, Rocket SSTO are very simple rockets. No staging, constant aero profile and VERY scalable. I find the easier to fly that classic staging rokets. I built the 600T variant of my rocket series in 10 minutes starting from the 300T. I just added radial tanks, engines, and checked I had 3400m/s and a reasonnable TWR. I added airbrakes, fins, checked the staging. Off we go ! First try = success.

They are also very cheap. I use the 150tons to LKO model a lot. Sure it costs 260k funds (not including the payload), but you'll get more than 200k funds back.

[GoSlash27]

Well...

My shuttle weighs 240t on the pad and delivers a 7t payload in orbit; about a 3% payload fraction. I could easily build a 50t disposable lifter or a 30t SSTO spaceplane to lift the same payload.

It costs $44,000 per flight, which is also way more expensive than the other methods. A disposable lifter can do the same thing for less than $7,000 and an SSTO spaceplane can do it for less than $1,000.

Worst of all it's harder to design and pilot than either of the other two methods.

The STS design is horribly impractical in KSP. The only reason it's worth doing is because it's one of the most difficult challenges the game has to offer.

Best,

-Slashy

[Val]

...

The STS design is horribly impractical in KSP. The only reason it's worth doing is because it's one of the most difficult challenges the game has to offer.

...

I agree. Doing a Shuttle replica should only be done for the challenge.

[Vegetal]

I used mk2 shuttle designs for a bit, nerv powered ones included that went to jool and all. Only things lost were the tanks and the launcher engine. I used the sandwich design for most of them to simplify things, and they usually went to LKO in a single stage.

More economical than a rocket? Yes, I even managed to constantly land them on the runway for full recovery. But definitely the most economical you can get is the SSTO spaceplane. I also used the concept of an interplanetary ship tucked inside a mk3 space plane, which was uber economical, but the most time demanding, as you have to land the launcher as well as the payload.

In short, it depends on the amount of time you are willing to spend on it, and if you like the challenge. If you aren't willing to spend that much time building and flying space planes, I think the shuttle concept is solid as a way of being more economical, as long as the shuttle itself is somewhat small. If you want to lift some heavy cargo, you're probably better off using rockets anyway.

Ps: Even piggyback style shuttles can be reasonable if you think simple.

[Geher]

Fuel Tanks are very expensive in KSP. So a STS-like craft doesn't save you any money. It's even more expensive than a normal expendable rocket:

- You have to get the payload AND the orbiter into orbit (Costs extra fuel --> extra tanks)

- You're dumping that big expensive external tank (this costs the most)

- You're dumping the boosters on the side (they are cheap, but they are not for free)

What you can do is:

- Install StageRecovery mod and add chutes to the boosters.

- Add a HeatShield to the external tank and try to land it as near to the KSC as possible.

When you do this it'll actually be cheaper than an expendable rocket. But it's helluva lot of effort to build. And also not easy to fly. I've build one which can get 36tons (orange tank) to LKO. But I rarely ever use it, because often I have payloads of over 150tons. So as many have said before me, a SSTO rocket with some parachutes is easy, cheaper and better. The only downside is, it doesn't look as cool as a Shuttle.

[Warzouz]

Yes I agree with Geher, I'm not sur that classical staging rocket is more expensive that space shuttle.

[Vegetal]

Oh yeah, it's only reasonable if the shuttle itself is the payload. If not, you're better off with a conventional lifter.

[Clipperride]

And remember the real Shuttle itself was something of a fudge. The military imposed some pretty tough requirements (possible polar orbit, a large cross range on the glide back to accommodate Edwards Air force base and demands about cargo bay size) in return for a double headed request for funding. In the end the Shuttle didn't provide the price per KG of payload breakthrough the original designs were looking for.

It may be as well to learn from the Shuttle and build something more suited to the job, unless you want to recreate an iconic design. For extra credit you could recreate the atmosphere that the real Shuttle was designed in: write out 10-12 different mission requirements. Pick 5 at random and then build something that satisfy them all!

[More Boosters]

Well, I mentioned space shuttle to imply recoverable spacecraft launched vertically without airbreathing engines; I can see why shuttle replicas could fail but is the consensus that no matter how you design them, they'll be inferior to an actual disposable rocket in cost effectiveness? I mean, RCS and Engines are pretty expensive; a reason for me to not put RCS on a rocket most of the time. The engines themselves are quite expensive too, especially nuclear ones.

[Skorpychan]

Well, if you want a recoverable rocket, go with the SpaceX Falcon design, and recover the main stage.

I mean, if you design it to haul the whole rocket up into space, you can circularise the upper stage and then switch back to the first stage to land it.

[nothingSpecial]

Well, I mentioned space shuttle to imply recoverable spacecraft launched vertically without airbreathing engines; I can see why shuttle replicas could fail but is the consensus that no matter how you design them, they'll be inferior to an actual disposable rocket in cost effectiveness? I mean, RCS and Engines are pretty expensive; a reason for me to not put RCS on a rocket most of the time. The engines themselves are quite expensive too, especially nuclear ones.

It's not that difficult to make pure SSTO rocket. It's not that difficult to land launcher either. Payload fraction will suffer, but if you care for recoverability...

Also why do you mind vertical launch with airbreathing engines? It was easier in 0.90 than in 1.04, but still possible. I had some fun with such designs, but I mainly tried to make rocketship SSTO, not shuttle one.

[Warzouz]

The issue with airbreathing/rocket SSTO is the airbreathing engines are quite small in size. You need a lot of them to liftoff a heavy payload.

Further more, engine are more expensive than rocket engines and you need a lot of them + a regular rocket for high atmo and space burns.

Rocket SSTO uses the same engines all the way to LKO (including orbit insertion). They are most simplest rockets.

It's doable, but I doubt the cost/ton would be efficient, even most of the rocket price is recovered.

[Vegetal]

Well, I mentioned space shuttle to imply recoverable spacecraft launched vertically without airbreathing engines; I can see why shuttle replicas could fail but is the consensus that no matter how you design them, they'll be inferior to an actual disposable rocket in cost effectiveness? I mean, RCS and Engines are pretty expensive; a reason for me to not put RCS on a rocket most of the time. The engines themselves are quite expensive too, especially nuclear ones.

Well then, take a look at my first post here. I think shuttles are valid if you have the skill to land back in KSC without power.

[Snark]

Another point to consider is just what expense it is that you're trying to save. Simply building something to get a not-too-massive payload into LKO is generally pretty cheap, even if it's not SSTO and you're throwing away the booster stages.

"But I want to go places beyond LKO, with expensive hardware!"

...Then use completely-reusable orbital transfer tugs. Launch a craft with high Isp engines that never comes down again; it docks to your missions and boosts them where they need to go. 100% reusable, and the engineering isn't subject to the constraints that spaceplanes impose. More to the point, they're more efficient: you don't waste fuel shipping heavy engines and other components up to orbit and down again. And you're free to use engines with good vacuum Isp without having to care about atmospheric.

"But I want to launch really heavy payloads!"

...Most payloads that are super-heavy are only that way because they have huge amounts of fuel. If you're concerned about expense, it's silly to ship fuel up from Kerbin-- mine it off Mun or Minmus and use it to stock a fuel depot in LKO.

If you're not shipping bulk fuel off Kerbin, and you're using a reusable high-vacuum-Isp tug to do orbital transfers, then launching off Kerbin surface becomes a whole lot cheaper. All you need to launch is actual mission hardware.

[Vegetal]

Yeah the tug approach is also very economical, but also very time demanding. A bunch of options here really.

[Snark]

Yeah the tug approach is also very economical, but also very time demanding. A bunch of options here really.

Yeah, definitely. It largely comes down to play style.

For example, in my own games, I find that the scarce resource is generally not cash, but rather my own play-time. If all I want is cash, it's easy, just skim through contracts until I get "launch new station on solar orbit" and jump on it. Quick, easy, takes like five minutes of my time, pays off anywhere from $500K to $1M or so. That pays for an awful lot of launches and I don't need to muck around with trying to recover hardware.

On the other hand, "play cash-poor" can be a fun challenge, too-- setting up a mining operation and building a big fuel depot can be fun.

[Nothalogh]

The STS design is horribly impractical in KSP. The only reason it's worth doing is because it's one of the most difficult challenges the game has to offer.

There's also the cool factor

[Exploro]

(ask any pilot, landing safely is the hardest part of flying).

I've flown before I can say that is not true most of the time.

Most landings are pretty benign affairs especially in light airplanes. I can see a few modes where that statement maybe true.

• Landing in incredibly poor weather conditions
  
• Aircraft carrier landings
  
• Landing on an "off field" strip (think bush pilots)
  
• ^Either of these operations being conducted at night.
  

[Vegetal]

As a helicopter pilot myself, the hardest part is learning to hover and autorotations

[Exploro]

As a helicopter pilot myself, the hardest part is learning to hover and autorotations

As yes; helicopter ops! I forgot all about that. Forgive me for looking at aviation solely from the perspective of flying fixed wing aircraft.

[Randazzo]

The way I see it, the economics of KSP has two important facets (like everything else..): Time and Money.

If you save on one, it's going to cost you the other and there's no way around it. Depending how much you value your time, this leaves the worth of time-consuming recoverable options to be rather subjective to the individual.

I've built a cargo shuttle, and found the time requirements compared to the savings garnered to be intolerable. I don't want to have to return a crewed vehicle and risk disaster every time I put a piece of a station or satellite in orbit. That doesn't mean everybody would feel the same.

[The_Rocketeer]

I've flown before I can say that is not true most of the time.

Most landings are pretty benign affairs especially in light airplanes. I can see a few modes where that statement maybe true.

• Landing in incredibly poor weather conditions
  
• Aircraft carrier landings
  
• Landing on an "off field" strip (think bush pilots)
  
• ^Either of these operations being conducted at night.
  

So which parts of flight would you have said were harder? Conditions being equal, I would have always said that landing without accident was harder than taking off, level flight, or in-flight manoeuvres. I'd go so far as to argue that a large majority of all KSP flights that end catastrophically do so when landing (deliberately or otherwise).

@Vegetal, well choppers are a rather different animal... I was also assuming linear aerodynamic flight.

Edited September 15, 2015 by The_Rocketeer