Are shuttles uneconomical?

[Rusty6899]

For a while I had wanted to make a space shuttle on KSP, but had never really got round to it until the last few days, when I thought I'd give it a try. After a fairly long time tweaking things in the SPH and numerous unsuccessful test flights, I managed to make a shuttle that performed pretty well. It consisted of a launch stage with 2 S1 SRB-KD25k's radially mounted to an orange tank, which fed fuel into my shuttle. The shuttle has 3 LV-T45's (2 firing initially and a third for when the SRB's finish burning to balance the thrust vector). The shuttle was fairly small (Mk 2 parts), had a small cargo bay and a small monopropelant tank for completing my orbit.

Putting a small satellite in orbit from the cargo bay, costs me about 25,000 funds (it could be reduced by taking fuel out of the orange tank as I have a fair bit more delta-V than I need). By comparison, I could mount the satellite to a rocket and get it into orbit for maybe 5,000 funds.

Is there a reason that the shuttle option is so expensive? I'm guessing fuel may be disproportionately expensive when compared to engines. Obviously, the main difference is that I am putting an entire spaceplane into orbit compared to just a satellite, but I thought the whole point of the shuttle was to make the expensive stuff reusable.

I'm sure people have managed to make KSP shuttles that have a much better economic efficiency than mine, but I don't see how you could even come close to making up the cost difference between a shuttle and a rocket.

Edited December 28, 2014 by Rusty6899

[Rakaydos]

Is that after the 100% recovery from landing on the runway?

[Anquietas314]

In short, yes, space shuttles are really a terrible idea for economic efficiency - the cost of two of those SRBs - never mind ditching the orange tank - makes it not worth while. Scott Manley did a

on designing them a few weeks back that went into the economics of it later on in the video.

[The_Rocketeer]

In short, yes, space shuttles are really a terrible idea for economic efficiency - the cost of two of those SRBs - never mind ditching the orange tank - makes it not worth while. Scott Manley did a

on designing them a few weeks back that went into the economics of it later on in the video.

True,IN KSP.

In RL, and the part the Ruskis never quite got to grips with with the Buran, is the NASA shuttles' engines - by far the most expensive part of the engineering - were 100% reuseable. Compared with multi-stage rockets for equivalent payload, the shuttle was a quantum leap advance in economy, with the only physical loss being the external tank, which was designed to be disposable.

Scott Manley's video (which I have seen) wasn't a very thorough exploration of what can be done, and makes viable shuttles look far more costly than necessary - the NASA model is workable and is still very parts-efficient compared to multi-stage ascents. However the engineering challenge of building a functional shuttle is by no means for all and given KSP physics, dimensions and handling (read loss) of parachute-borne parts, there's no economic reason to use them over another SSTO vehicle.

P.S.

From the sounds of it you're using more SRB thrust than you need to for your Mk2 Shuttle - with some careful engineering you should be able to complete the ascent with a pair of BACCs and save some Kerbucks.

Edited December 27, 2014 by The_Rocketeer

[Hattivat]

In real life it was an even more horrible idea than in KSP. Reusable my ***, "the average cost per flight was about US$1.5 billion" - that is 50% more than a Saturn V launch (inflation-adjusted, of course), for one fifth of the payload.

[Rusty6899]

Is that after the 100% recovery from landing on the runway?

Yes, I actually did use a fair few reaction wheels to maintain stabiity (I may be able to take them out). If they were taken out it would be 20k in unrecovered items.

In short, yes, space shuttles are really a terrible idea for economic efficiency - the cost of two of those SRBs - never mind ditching the orange tank - makes it not worth while. Scott Manley did a

on designing them a few weeks back that went into the economics of it later on in the video.

I had seen the Scott Manley video a few weeks ago, and it was part ofthe reason I decided to make one. I'll just have to keep it for Sandbox rather than Career. I'll probably go for a SSTO or a Mk 3 shuttle next. Although, I have heard that the Mk 3 parts aren't the most user friendly.

[Anquietas314]

In RL, and the part the Ruskis never quite got to grips with with the Buran, is the NASA shuttles' engines - by far the most expensive part of the engineering - were 100% reuseable. Compared with multi-stage rockets for equivalent payload, the shuttle was a quantum leap advance in economy, with the only physical loss being the external tank, which was designed to be disposable.

Well, okay, how about the money spent just developing the space shuttle? That thing was not cheap by any means. According to this, in modern terms it cost on average $450 million per launch, with a net cost for the full 30 years in service of $196 billion. There were 135 missions flown, which equates to just shy of $61 billion, or in other words ~$120-125 billion in development costs alone.

Compare this to the cost of SpaceX's Falcon 9, which can lift almost half the payload of the space shuttle, for $61.2 million per launch (source). Yes that's a much more recent design, but had NASA's budget been spent on developing something similar instead of the space shuttle, it would most likely have been far cheaper.

Edited December 27, 2014 by armagheddonsgw

[Pecan]

The answer remains the same in all the many threads about 'shuttles'.

With careful design, in KSP:

1. A 'US-style' shuttle is still awful

2. A SSTO rocket is simple to build (for ~98% recovery)

3. A vertical-launch/landing jet SSTO, with rocket(s) for circularisation is more efficient

4. A spaceplane is harder to build than either, for an extra ~2% recovery, but looks cooler

[The_Rocketeer]

In real life it was an even more horrible idea than in KSP. Reusable my ***, "the average cost per flight was about US$1.5 billion" - that is 50% more than a Saturn V launch (inflation-adjusted, of course), for one fifth of the payload.

I don't really see how that's relevant. I was highlighting the cost-advantages of the vehicle, not the administrative costs of bloat-NASA's mission expenditure.

Compare this to the cost of SpaceX's Falcon 9, which can lift almost half the payload of the space shuttle, for $61.2 million per launch (source). Yes that's a much more recent design, but had NASA's budget been spent on developing something similar instead of the space shuttle, it would most likely have been far cheaper.

As above. I don't really see the advantage of comparing modern rocket design costs with 1970s era NASA design costs. Development budgets and actual bread-and-butter mission costs are two different things.

I'm not trying to suggest that the Shuttle was the best way to do things. Most organisations work to budget, and NASAs 1970s budget was very, very large. Why bother making it cheap when you can make it expensive? Nonetheless, the Shuttle remains a very successful experiment, albeit one that's rather dated by modern standards and inferior in the light of other technological advances.

[Anquietas314]

I don't really see how that's relevant. I was highlighting the cost-advantages of the vehicle, not the administrative costs of bloat-NASA's mission expenditure.

--snip--

Most organisations work to budget, and NASAs 1970s budget was very, very large. Why bother making it cheap when you can make it expensive?

Let's not derail this thread, but you can't argue that it was economical and (needlessly) expensive - those are directly contradictory terms. As for comparing the 1970s era design with modern ones - the costs for the NASA stuff have been scaled for inflation. That is, it would cost about the same as those figures if it were done now instead. Development costs are very relevant - if it costs more to develop a design than you will save by using it, it's a terrible idea. In the case of the shuttle, the development costs dwarfed even the usage costs, never mind savings.

[UmbralRaptor]

SSTOs that use jet engines to get 99% of the way to orbit and land at the runway are about the cheapest launchers possible in KSP. But if it relies on rockets or has expendable parts, beating out

Most organisations work to budget, and NASAs 1970s budget was very, very large. Why bother making it cheap when you can make it expensive?

This is literally the opposite of what happened. NASA's budget was dramatically reduced in the late 1960s and early 1970s, killing off most post-Apollo plans that weren't the shuttle. The shuttle itself made design compromises to reduce development costs (the SRBs and expendable nature of the external tank), though they increased (or at least were expected to increase) operational costs. And then there was the sizing issue from trying to get the air force involved. I'm not clear if NASA got money from them directly or if it was just to get more customers so that the projected flight rate of >50 / year could be pulled off.

[numerobis]

One large cost in the NASA shuttle was the time it took to refurbish it after every flight (in part due to the tiles that kept falling off or breaking).

I've seen estimates that range from $100M to $1.5G per flight, depending on how you count: fuel and operations for a mission is something like $100M, which was roughly the goal assuming frequent launches. I don't remember what got counted into the $450M, but that was in part because there were far fewer launches than expected, and a lot more downtime between launches, and a much higher failure rate. All costs for the program divided by the number of flights that actually flew is $1.5G per launch.

Accounting is an art; you've got some cash flows and it's up to what story you want to tell how you add them up. If you want to say the shuttle was expensive, $1.5G is your number. If you want to say it was cheap, $100M is your number.

Refurbish time and development cost aren't an issue with KSP: we can turn around a spacecraft in a couple seconds flat.

[Torquemadus]

The potential pitfall of using a shuttle in KSP, is that you can end up making the wrong part of the vehicle re-useable.

In KSP, liquid fuel tanks have a high cost compared to the fuel they contain, making it highly desirable to recover them after use. Solid rockets are worth next to nothing once empty, they are "trash bins full of boom". Therefore, if you want to make an efficient two-stage-to-orbit lifter in KSP, you can afford to throw away solids, but you want to recover any liquid fuel tanks and engines you use.

The largest stock solid rocket in KSP at the moment is the SRB, which has quite weak thrust compared to the bigger liquid engines, such as the Mainsail. If you build a lifter that looks like a NASA Shuttle, you'll probably use a pair of SRBs and a bunch of liquid engines. The liquid engines will end up doing most of the work and will end up using a heck of a lot of fuel, all of which is drained from an external tank that you aren't going to re-use, and you won't have much of a mass fraction left to haul cargo.

Therefore, what you're actually doing is making an expendable stage-and-a-half-to-orbit launch vehicle, that lifts a re-useable upper stage (the orbiter), which has incredibly high dry mass. The upper stage only has OMS engines for propulsion, which have limited fuel. The orbiter then offloads the payload, which has much lower mass than the orbiter. The orbiter then de-orbits and returns to the runway. Recovering the orbiter means that you get the engines back, but most of the parts you recover are parts you could have done without having to lift into orbit in the first place!

Of course, what you really want to do is make the launch vehicle re-useable!

By the way, if you want to read up on the development of the real Shuttle, there's an online book here: http://www.nss.org:8080/resources/library/shuttledecision/index.htm

[Anquietas314]

Of course, what you really want to do is make the launch vehicle re-useable!

I'll just add to this that, at least in KSP, making a reusable SSTO launcher that just decouples a payload and returns to Kerbin is much cheaper (and easier) than getting a shuttle design to work, even if you do recover the big orange tank

[The Silent Majority]

True,IN KSP.

a quantum leap advance in economy.

You are aware what a "quantum leap" is, right?

[The_Rocketeer]

You are aware what a "quantum leap" is, right?

No, I don't know what a quantum leap is. I was making a figurative expression using language I don't understand. So sue me.

Yeesh. Look out for the precision police.

To stay on topic, in KSP it's not uneconomical to build a craft that does the job you intended it for within a budget that you consider reasonable. If shuttles meet those criteria, use them. If you derive the same satisfaction as I do from engineering such a craft and making it work, remember to factor that satisfaction into your design specification. Otherwise you become bored, jaded, and trawl the forum for unwitting contributors that you can mock and detract with your superior intellect.

Edited December 27, 2014 by The_Rocketeer

[Pecan]

No, I don't know what a quantum leap is. I was making a figurative expression using language I don't understand. So sue me.

Yeesh.

's the extrovert version of quantum tunneling*. Personally, I've always preferred reversing the polarity of the neutron flow. Well, it works for

.

Anyway, I know what you meant ^^.

[*alright, no it isn't]

[GoSlash27]

Like the others have said, the shuttle concept is not economically viable in KSP and didn't prove itself economical IRL either.

Plain old layer cake rockets were always able to put payloads into orbit for less $ per kilo, which is why we're going back to them.

SSTO spaceplanes, OTOH, are capable of putting payloads into orbit for ridiculously cheap. At least in KSP.

Best,

-Slashy

[AlexanderB]

Yeah, ditch the orange tank and SRB's, a shuttle-sized SSTO plane will orbit just fine without them in KSP, and do runway-->orbit-->runway with a couple of tons of cargo or a dozen+ kerbals for the price of just some liquid fuel..

On the other hand, a simple probe can be shot to kerbin orbit with just a small fuel tank and a single engine, or stick a SRB under it to boost its range to mostly anywhere in the kerbin system, especially if you use ion propulsion on the probe.

[Skorpychan]

Not in KSP. It also won't work right because KSP physics aren't real-world physics.

Really, what you need is something akin to the saturn-shuttle, which is a Shuttle stuck atop a Saturn V lower stage.

[GoSlash27]

You are aware what a "quantum leap" is, right?

Scott Bakula is not impressed

-Slashy

/dating myself

[Anquietas314]

Scott Bakula is not impressed

-Slashy

/dating myself

Eh, that show isn't that old, and it's quite well known

[GoSlash27]

Eh, that show isn't that old, and it's quite well known

The last episode was over 20 years ago. I'm pretty sure there's at least a dozen kids googling "Scott Bakula" at this very moment.

I used to like that show, too...

/I feel so...old...

-Slashy

[Anquietas314]

The last episode was over 20 years ago. I'm pretty sure there's at least a dozen kids googling "Scott Bakula" at this very moment.

I used to like that show, too...

Well sure, but remember the last episode of Star Trek: The Next Generation was exactly 20 years ago. People still watch that (granted it's not quite the same thing, but still), then of course there's the original series, etc. Also, I never said I watched quantum leap

We're getting way off topic too lol.

[Heagar]

Shuttles - NASA-style - are at liftoff winged rockets and their rocket engines consuming fuel at an alarming rate --> therefore they are a costly choice. Because the SRB's and the external tank aren't reusable in KSP (you can fit them with chutes, but they will unspawn at a certain distance), only 1/3 of the craft lands after an mission.

The NASA build the shuttle at an time, where reusable seems to be an good choice for cheap space access.

The HL20 progam (some kind of Sänger approach) was shut down in favor of the shuttle because that had an chargo bay. And as always with new ideas some assumtions were put into the calculations for the feasability.

This new spacecraft should be able not only to release sattelites, but also repair them or catch them for repairs on the ground. Well, i've only heard about the "repair"-mission for the space telescope hubble. Nothing about that an shuttle brought back an crippled sattelite.

Of course the military was interrested in the shuttle at that time too, because it could be usable in the SDI program. And two third of the hole missions of the shuttles where military ones. But i doubt that they transported a single component for the SDI project, more likely spy sattelites and so on.

The problems for the shuttle where it's high maintainance costs (e.g. ceramic plates, where everone had an unique shape). But it was the only way at that time to build an partially reusable spacecraft.

Only years before the X-15 was tested up to Mach 6, and an spaceplance seemed not to be an soloution if you look at that damage caused by heating (sprayable ablative coating partially gone).

Annotation:

Sorry for an external source, but NASA's NTRS server doesn't responds.