Wings and their worth

[NFunky]

Hey guys,

So I'm playing KSP with 3.7x scale planets and distances. I'm not that new to the game, but new enough that I never bothered to develope an SSTO before switching over to the larger scale. It's still not real world orbital speed (approx. 4500), but it's significantly higher than stock, and I've found payload fractions and rocket design to be close enough to real life for now.

Currently, I haven't gotten far enough in my career to have turbojets, aerospikes or RAPIERs. I'm about to complete a mun mission that will net me enough science to aquire one of these, but as of yet I don't have any. Thing is though, I'm building this modular mothership to use for the mun mission and an upcoming Duna shot, possibly even more, as it can be refueled back at Kerbin. I've been using a shuttle to bring up components and I'm not spending THAT much money, due to parachute recoverable (FMRS) boosters and first two (of 4) external tanks. I still lose those last tanks though, and the boosters and first tanks only get a fraction recovery because of how far down range they are.

Okay, so I guess my question is, economically, if I'm playing with this large scale Kerbin, is it worth it to go for any of the classic SSTO tech, or just go back to using disposeable or maybe at least 1st stage recoverable rockets? BTW, I have scaled up reentry heating as well, so the upper stages of a rocket would be quite hard to recover.

All the threads I've read on these forums basically say that shuttles are not very economical, no matter what, those are all talking about a normal scale Kerbin. And as far as SSTOs, is this orbital velocity (4500 with the same 70 km atmosphere) impossible for a scaled up classic KSP air-breather? Do you guys think winged spacecraft of any sort are at all economical in 3.7x?

I'm assuming if I use turbojets or RAPIERs, I can get about 1,100 m/s before I hit 30 km, but after that I still need about 4,000 dV of pure rocket power to make orbit. Are aerospikes my best bet? Maybe with a single turbojet for initial ascent? Any discussion on real world SSTOs and partially reuseable vehicles welcome as well of course. I don't know where the deviding line is between KSP scale and real life that makes the usual SSTOs relatively easy in stock.

Thanks

[GoSlash27]

Hey guys,

So I'm playing KSP with 3.7x scale planets and distances. I'm not that new to the game, but new enough that I never bothered to develope an SSTO before switching over to the larger scale. It's still not real world orbital speed (approx. 4500), but it's significantly higher than stock, and I've found payload fractions and rocket design to be close enough to real life for now.

Currently, I haven't gotten far enough in my career to have turbojets, aerospikes or RAPIERs. I'm about to complete a mun mission that will net me enough science to aquire one of these, but as of yet I don't have any. Thing is though, I'm building this modular mothership to use for the mun mission and an upcoming Duna shot, possibly even more, as it can be refueled back at Kerbin. I've been using a shuttle to bring up components and I'm not spending THAT much money, due to parachute recoverable (FMRS) boosters and first two (of 4) external tanks. I still lose those last tanks though, and the boosters and first tanks only get a fraction recovery because of how far down range they are.

Okay, so I guess my question is, economically, if I'm playing with this large scale Kerbin, is it worth it to go for any of the classic SSTO tech, or just go back to using disposeable or maybe at least 1st stage recoverable rockets? BTW, I have scaled up reentry heating as well, so the upper stages of a rocket would be quite hard to recover.

All the threads I've read on these forums basically say that shuttles are not very economical, no matter what, those are all talking about a normal scale Kerbin. And as far as SSTOs, is this orbital velocity (4500 with the same 70 km atmosphere) impossible for a scaled up classic KSP air-breather? Do you guys think winged spacecraft of any sort are at all economical in 3.7x?

I'm assuming if I use turbojets or RAPIERs, I can get about 1,100 m/s before I hit 30 km, but after that I still need about 4,000 dV of pure rocket power to make orbit. Are aerospikes my best bet? Maybe with a single turbojet for initial ascent? Any discussion on real world SSTOs and partially reuseable vehicles welcome as well of course. I don't know where the deviding line is between KSP scale and real life that makes the usual SSTOs relatively easy in stock.

Thanks

If the air density and gravity are the same, then spaceplanes should achieve the same performance as stock. RAPIERs can exceed 1500 m/sec even at very heavy loads. Turbojets can exceed 1100 when heavily loaded.

Basically it's the same thing as building an SSTO spaceplane with an additional 2,200 m/sec DV. I'm thinkin' that's doable at a comparable payload fraction to conventional staged rockets.

I have a 24t SSTO spaceplane that carries 8.6t of cargo to orbit in stock KSP; 36%. It weighs roughly 13t in orbit, so my back-of-the-envelope says it can hit that orbit with 3.8t payload. That's about 16%, which is in-line with staged lifters.

Best,

-Slashy

Edited August 31, 2015 by GoSlash27

[Geschosskopf]

Even with the stock-sized solar system, SSTO spaceplanes don't have much practical value. As you increase the size of the solar system, their value becomes even less. So unless you just want to play with them, either as a challenge or because it's just your thing, my advice is to just avoid them. They really don't save you enough money to be worth the trouble unless you've set some harsh difficulty options concerning money. If you're playing with default or easier money settings, then you'll have so much money that reusable spacecraft have no real value. And this is especially true before you unlock the whole tech tree. What's the point of being able to refuel a Duna ship that will be obsolete by the time it returns?

The general things about spaceplanes are as follows:

* NOTE: This all assumes you want a "useful" spaceplane but "useful" means different things to different people. To me, "useful" means capable of carrying a decent load to LKO. Therefore, I define "useful" has carrying at least 4 Kerbals AND can dock, or can carry something requiring the long cargo bay and can get home again without refueling. Those are my minimum standards. If it can do more but if it can't do either of these things, then there's no real point in having it.

* Spaceplanes are just an alternative form of lifter, just to get stuff from the ground to LKO (and maybe back). Even in stock-sized solar systems, they're not really capable of going farther without making their payload fraction too small to be worth the trouble.

* A spaceplane's utility as a payload lifter is limited by the size of its cargo bay. With the Mk2 parts, you payloads can only be 1.25m without much stuff radially attached. With Mk3 parts, its the same only with 2.5m. If your payloads have any real width to them, then they won't fit in a cargo bay and you have to use a rocket anyway.

* The more dV needed to reach orbit due to solar system size, the less useful spaceplanes become and the harder they are to make work.

* Spaceplanes are huge timesinks. They require much more time to build and tweak than rockets, they take much more time to reach (or fail to reach) orbit, and are very dependent on being flown correctly so it's hard to tell sometimes whether the design is flawed or you just need to fly it differently. As a result, you can easily spend all of several days tweaking a single design before even being able to decide it doesn't work and having to start over. OTOH, you can usually slap a rocket together in 5 minutes and be pretty much assured it will work the 1st time. Some folks groove on the spaceplane design grind, others don't. To me, this is the biggest turn-off of spaceplanes and is why I rarely use them.

* Once you've gone to the trouble to make a "useful" spaceplane, all you have is something that can carry a small (both in mass and dimensions) cargo to LKO. Assuming you can then land it safely on the runway, you can use it repeatedly for only the cost of the fuel it consumes. But this low operating cost isn't at all significant in the game unless you're either broke or plan to use the spaceplane many times.

[GoSlash27]

^ I agree with all of this, which is why I only use SSTO spaceplanes for routine logistics flights to LKO. Transporting crew to orbit and back is a function you have to do fairly often. Ditto carrying fuel/ oxidizer and monoprop to orbit. Spaceplanes are good for these mundane jobs.

Everything else, I use conventional lifters.

Best,

-Slashy

[Geschosskopf]

^ I agree with all of this, which is why I only use SSTO spaceplanes for routine logistics flights to LKO. Transporting crew to orbit and back is a function you have to do fairly often. Ditto carrying fuel/ oxidizer and monoprop to orbit. Spaceplanes are good for these mundane jobs.

Everything else, I use conventional lifters.

Yup, a glorious, sweet-looking spaceplane is really just a mundane, short-haul delivery truck. However, the need for these "beer runs" varies a lot with playstyle and somewhat with your position in a career game, and a lot of that ultimately revolves around the size of your wallet. If you can afford to do everything with 1-shot rockets, then spaceplanes have no economic attraction and become simply a matter of taste.

Also, 1.1 will impose some stock version of AntennaRange. Therefore, everybody will need some sort of commsat constellation at Kerbin, Mun, and Minmus. So there you have a bunch of things needing to get to LKO and probes easily fit inside cargobays. However, probes are very cheap to launch with rockets and you'll need to have the network in place early on, long before you unlock spaceplane engines. So by the time you can make a probe-launching SSTO, it won't have a job anymore, and probably won't save you much money anyway given the cheapness of probe lifters.

[Hagen von Tronje]

I find building spaceplanes a lot of fun but the closest to "practical" I can make them is retrieving kerbals from orbit. I keep chasing the dream of a SSTO spaceplane that goes to LKO, refuels, goes to Eve orbit, refuels, lands on Eve, refuels, then does the same in reverse, from runway to Eve surface back home. It...is not an easy dream.

[Reddeyfish]

Also, 1.1 will impose some stock version of AntennaRange. Therefore, everybody will need some sort of commsat constellation at Kerbin, Mun, and Minmus. So there you have a bunch of things needing to get to LKO and probes easily fit inside cargobays. However, probes are very cheap to launch with rockets and you'll need to have the network in place early on, long before you unlock spaceplane engines. So by the time you can make a probe-launching SSTO, it won't have a job anymore, and probably won't save you much money anyway given the cheapness of probe lifters.

They're also adding a Deep Space Network to Kerbin, so the kerbin commsats aren't necessary.

[Vegetal]

I guess it's doable, but you will carry less payload to orbit than on a stock game.

As they pointed out already, it depends on your wallet and your willingness to design a good plane. If cost is starting to be a concern for your game, then it's probably a good idea.

[panzer1b]

I find building spaceplanes a lot of fun but the closest to "practical" I can make them is retrieving kerbals from orbit. I keep chasing the dream of a SSTO spaceplane that goes to LKO, refuels, goes to Eve orbit, refuels, lands on Eve, refuels, then does the same in reverse, from runway to Eve surface back home. It...is not an easy dream.

Im similar, except ive officially given up on both types of SSTEs (single stage to eve/eeloo and back without any irsu or refueling). At least laythe is possible.

As for practicality, i agree with some of the above posters, there is absolutely no reason for making single stages to wherever unless you want some kind of reuseable refueleable lander (for say duna or laythe or even kerbin) in sandbox where funds do not matter. I dont know why, but i just always liked the concept of single staged fighter style craft like starfighters or whatnot in alot of sci-fi movies that dont need to refuel at all more or less, and can go very very far distances. That and i enjoy the challenge of making these things, hard as hell, yes, but you cant say making a SSTL (single stage to laythe and back) isnt at least somewhat of an accomplishment as you dont really see many of those around after 1.04 hit. The only thing im not too happy with is the fact that my HK-201 abuses part clipping to no end, but i fail to see any other way to make it work in the 1st place while keeping a very specific external appearance (there is just no volume to place fuel left that isnt taken up by bombs/missiles).

And im quite lucky i brought enough wings, they give it a hair too much lift on kerbin, but at least they let you land on duna at ~80m/s, which is survivable if you know how to avoid death-jumps on the surface.

Anyways, to answer the OP question, i find SSTOs to be perfectly viable, although the more dV you need, the more attractive multi-stage systems are, since there is only so much you cab pull from one stage in terms of dV. While i may very well be wrong, rockets are better for payload fractions, and are (obviously) far easier to create. If you enjoy the challenge, its perfectly possible to make a SSTO work with the RSS mod, it just requires alot more engineering (and you can FORGET about going to other planets with it without any refueling). My best craft (non military one) had ~5.5K dV in orbit using teh stock solar system, and its TWR was not something id call bad so it may or may not work with larger systems depending on how much extra dV you need to get orbital (if you can keep from loosing altitude on just nukes then it should keep going to orbit albeit slowly).

Edited August 31, 2015 by panzer1b

[Geschosskopf]

They're also adding a Deep Space Network to Kerbin, so the kerbin commsats aren't necessary.

Well, AFAIK it'll be like Antenna Range where you don't need the RT-style geosynchronous constellation. However, Kerbin itself can only talk so far so to talk to other planets, you'll need relays. The easiest way to do that in AR is to put a pair of big dishes in highly elliptical polar orbits, one going up and the other down, and out of phase with each other so that when one probe is near its Ap, the other is near its Pe. That way, they both spend most of their time out near their Aps, which are far enough above and blow the ecliptic that they can see over any intervening planets.

[Hagen von Tronje]

Im similar, except ive officially given up on both types of SSTEs (single stage to eve/eeloo and back without any irsu or refueling). At least laythe is possible.

As for practicality, i agree with some of the above posters, there is absolutely no reason for making single stages to wherever unless you want some kind of reuseable refueleable lander (for say duna or laythe or even kerbin) in sandbox where funds do not matter. I dont know why, but i just always liked the concept of single staged fighter style craft like starfighters or whatnot in alot of sci-fi movies that dont need to refuel at all more or less, and can go very very far distances. That and i enjoy the challenge of making these things, hard as hell, yes, but you cant say making a SSTL (single stage to laythe and back) isnt at least somewhat of an accomplishment as you dont really see many of those around after 1.04 hit. The only thing im not too happy with is the fact that my HK-201 abuses part clipping to no end, but i fail to see any other way to make it work in the 1st place while keeping a very specific external appearance (there is just no volume to place fuel left that isnt taken up by bombs/missiles).

http://i.imgur.com/tRcFswE.png

One of the big barriers I find is that it's just more practical to have reusable vehicles for each leg.

SSTO to LKO rendezvous? Easy enough.

Reusable transfer from Kerbin to planet of choosing? Also not THAT hard, especially if you have fuel stations at the destination.

But not on the same vehicle. I just think it's simpler to make a reusable travel network where you SSTO then transfer craft at the station.

Still, like you, I love the idea of a "personal space yacht" a la Heinlein (esp Lazarus Long's personal craft).

[panzer1b]

Well, AFAIK it'll be like Antenna Range where you don't need the RT-style geosynchronous constellation. However, Kerbin itself can only talk so far so to talk to other planets, you'll need relays. The easiest way to do that in AR is to put a pair of big dishes in highly elliptical polar orbits, one going up and the other down, and out of phase with each other so that when one probe is near its Ap, the other is near its Pe. That way, they both spend most of their time out near their Aps, which are far enough above and blow the ecliptic that they can see over any intervening planets.

Im just hoping they give us true droid brains instead of just probes.......

That or at least let us control probes from another vessel thats manned by skinjobs. This gives me an idea actually, DROID CONTROL SHIPS!

[moogoob]

Im just hoping they give us true droid brains instead of just probes.......

That or at least let us control probes from another vessel thats manned by skinjobs. This gives me an idea actually, DROID CONTROL SHIPS!

I think that using a manned ship to control probes is already planned to be a feature.

[Geschosskopf]

Im just hoping they give us true droid brains instead of just probes.......

That or at least let us control probes from another vessel thats manned by skinjobs. This gives me an idea actually, DROID CONTROL SHIPS!

A pox on you . Such archaic, stone-age things are totally incompatible with today's world of fully autonomous vehicles on land, sea, air, and space.