The purpose of the space planes

[seaces]

Hello everybody I am new to KSP and I have a question regarding the space planes.

Could somebody tell me a couple of good reasons why should I want to build space plane and use it? I am sorry if this was answered before but I just can't see any puprose of it since I can do everyting with rockets. Curently I am playing Science only career and I am build Mun station just after I have unlocked docking ports. I want to use station with lab module to explore Mun the fastest possible way with least trip and visit and explore it as much as I can before proceding to Minimus. So I have there a light lander with all experiments so I go land every tiem on different biome do experiment get back, dock it move experiments to Lab refuel do it again. If I need extra fuel I can easily send it from Kerbin.

So, give me a godd reason for using a space plane that is 1) dificult to build and balance it taking in account fuel movement, 2)I need 2 type of engins one for atmosphere run and another rocket engien for space activity 3) jet engines have their own fuel tanks and gear required to operate so extra weight and extra complications. Sorry I just can't see why should I build them and use them

[The_Rocketeer]

This isn't the most detailed or in any way conclusive list, but from the top of my head:

1: Most importantly, variety. (Not everybody gets their kicks from building phallic monstrosities.)

2: SPs are more fuel efficient than rockets per payload mass.

3: SPs are safer and cheaper to land on bodies with atmospheres than rockets.

4: SPs are reusable - rockets tend to come apart on the way up/down as they drop stages.

5: SPs look cool

6: One SP design can efficiently meet a very wide variety of mission profiles, whereas rockets are usually one-trick ponies.

But there's no right or wrong way to play KSP. If you're having fun with rockets and find SPs too difficult, boring or un-fun, don't worry about it - stick to what you love

Edited December 15, 2014 by The_Rocketeer

[bitslizer]

Curently I am playing Science only career...

What rocketeteer said...

expanding on #3 and #4... If you play in full career with funding, being able to send payload up into orbit for ONLY the cost of fuel (when you recover the SP at KSC) suddenly becomes very attractive if your goal is to bank as much funding as possible.

[shadowfax]

Economics, pure and simple. You can launch a space plane for little more than the cost of the fuel. Especially if you don't have the Stage Recovery mod, you lose money with every stage you jettison.

I still use rockets to get the big stuff up there, but if I'm doing a supply run to a space station, I take the space plane because it's so much cheaper.

[Oafman]

It's fun. It's much harder to make good planes than it is to make good rockets, so the additional challenge adds to the fun of the game.

Also, when you start building bases on places like Laythe, the re-usability of planes becomes vital.

[Kesa]

For your mun mission, since you don't bother money, there is no point of being fuel efficient, reusable to send fuel into space, or to land on the mun. However, learning to build plane is fun ! What's more plane shows you how little TWR is required to go to orbit horizontally enough : I tend to design good plane and to fly them well, but make over powered rocket, or I don't steer them enough. Designing a plane is way harder than a rocket, but a good plane with little margin is often more forgiving than a rocket on ascent path, and even easier to fly when you learned it (basically because the ascent is much longer, and when you do things wrong, you're just losing energy to drag, compared to have overshot your ap, or worse, to be unable to steer up a heavy rocket)

[Ziff]

Could somebody tell me a couple of good reasons why should I want to build space plane and use it?

Reuse-ability. It may not make any difference in your science playthrough, but it can make a huge difference in Career mode. A properly engineered SSTO spaceplane allows you to launch, perform a mission, and land back at KSC. This allows you to recover your entire craft for nearly the full amount it cost. You only lose money on the fuel. When rockets start costing $100,000+, and 95% of it gets dumped into atmosphere to burn up, spaceplanes can be a major savings that allows you to spend your money on other things. This will become more important in 0.90 when we have to spend funds on increasing the tech level of our buildings.

Fact: If you want to be monetarily efficient you need to recover as much of your craft as possible. SSTO Spaceplanes win here, hands down.

So, give me a godd reason for using a space plane that is 1) dificult to build and balance it taking in account fuel movement,

They aren't difficult to build, they are difficult to learn to build. There is a difference. Just like it took you time to learn the rocket equation and understand dV and TWR and other tidbits, the same goes for spaceplanes. Once you have the scientific understand you can easily knock together a bunch of spaceplanes. There are several mods that make building spaceplanes easier as well. I actually use the RCS Build Aid mod to see my center of mass with/without fuel. This lets me balance as I build so I never have to worry about fuel movement.

2)I need 2 type of engins one for atmosphere run and another rocket engien for space activity

Not true. The stock RAPIER and many other engines from other mods have a "Switch mode" feature that allows you to go from buring liquid fuel/air to liquid fuel/oxygen. Also, requiring two different types of engines isn't necessarily bad. It doesn't take much to finalize your orbit and you don't really need a high TWR for orbital maneuvers.

3) jet engines have their own fuel tanks and gear required to operate so extra weight and extra complications.

You don't have to add separate tanks, they burn the same liquid fuel as rocket engines. If you design it correctly you don't need to add additional tanks. Often what I do is figure out how much dV I need for my rocket engines to complete my mission. Then I build a plane and if I have too much rocket fuel I just pull out some oxidizer. The remaining liquid fuel is now extra fuel for my atmospheric engines.

[MarvinKitFox]

"The purpose of the space planes "

To have fun with?

To look cool?

To be different?

Ok, without emotion:

Economy:Spaceplanes tend to be both SSTO and returnable/recoverable, thus don't waste money by dribbling expensive bits all over the landscape.

Note that this is actually a benefit of recoverable SSTO's not spaceplanes per se. There are perfectly good non-aero-lift recoverable SSTO designs.

Jet engines: Jets in KSP have silly, huge, ludicrous ISP ratings. But they only like to operate in the low or mid atmosphere. This makes them *ideal* for planes, and not so hot for non-aero-lift launchers.

This basically means that jet-powered ssto planes are easy to build and efficient, but jet-powered ssto rockets are gain much less from the jet engine efficiency.

If you want to exploit the great efficiency of the ksp Jet Engines, you are kinda required to build them into a spaceplane design.

Edited December 15, 2014 by MarvinKitFox

[Voculus]

One thing about fuel consumption, and shifting centers of mass, I've found that delta-wing designs seem to suffer the most from this, since they typically have the engines in the rear, most of the lift in the rear, and all the fuel being drained forward to back, and moving the CoM quite far.

Planes with elevators in the rear, swept wings in the middle, and fuel tanks and engines mounted on those wings see a very limited shifting of mass, even when letting loose heavy cargo into orbit. Just something to consider. Either way will work just as well if designed right.

[Red Iron Crown]

They're fun, and cool. If you like rockets better, don't use spaceplanes.

Personally, I put payloads in orbit with rockets, only use spaceplanes for crew/science transfer.

[LethalDose]

As everyone has stated above, the economics of a spaceplane is what makes them appealing. SSTO spaceplanes tending to be more economically effective than staged planes. I find them most useful to cheaply bring "stuff" to and from LKO. "Stuff" may be kerbals, science, interplanetary probes, satellites, fuel, life support, etc. Larger stations parts can't be hauled up quiet yet (I think that will change within, literally, the next 24 hrs) since we can't fit 2.5m parts into cargo bays.

I personally don't think it makes sense to use SSTO spaceplanes beyond LKO. When engineering any space vessel, it's easier, simpler, and more efficient to design them to perform a specific task. My spaceplanes go from surface to LKO, and I have other vessels in orbit that are dedicated to operating from LKO to other locations. This is similar to the original STS proposed by NASA in the late 60s.

As you point out, you can do everything you need with a rocket. That's totally true, and if it's your play style, then you should stick with it. Personally, I tried making spaceplanes 4 or 5 times, and quit, throwing up my hands in frustration. They're a pain in the ***. I got them to work when I tried again, and I'm kinda glad I did. I still prefer rockets for a lot of heavy lifting, but there are some things that spaceplanes can do more efficiently and cost-effectively than rockets.

But if you're in science mode, cost really isn't an issue.

[Othuyeg]

Fun.

Yeah, they can be efficient aswell, but more importantly, fun.

[panzer1b]

Hello everybody I am new to KSP and I have a question regarding the space planes.

Could somebody tell me a couple of good reasons why should I want to build space plane and use it? I am sorry if this was answered before but I just can't see any puprose of it since I can do everyting with rockets. Curently I am playing Science only career and I am build Mun station just after I have unlocked docking ports. I want to use station with lab module to explore Mun the fastest possible way with least trip and visit and explore it as much as I can before proceding to Minimus. So I have there a light lander with all experiments so I go land every tiem on different biome do experiment get back, dock it move experiments to Lab refuel do it again. If I need extra fuel I can easily send it from Kerbin.

So, give me a godd reason for using a space plane that is 1) dificult to build and balance it taking in account fuel movement, 2)I need 2 type of engins one for atmosphere run and another rocket engien for space activity 3) jet engines have their own fuel tanks and gear required to operate so extra weight and extra complications. Sorry I just can't see why should I build them and use them

For starters, if you are playing career/science locked modes, spaceplanes are more or less useless until you unlock the turbojet/rapier (both of those work for spaceplanes), for landing on bodies without vaccum they are usually not that great (its quite possible, i made a nice SSTO that can do mun, minmus, and prolly get to duna in 1 trip, but a rocket wouldve prolly been better in terms of efficiency). As for complexity, you are correct, anything that needs to be aerodynamically viable takes alot more work to get working, and is arguably harder to fly (+ it takes a little more time then a classical brute-force rocket).

I am a almost exclusive SSTO designer (only thing i touch rockets for are capital ship sized stuff, as well gl trying to FLY a 500 part massive ship). Reasons i like SSTOs (and to a certain extent spaceplanes with jettisioned stuff), are their looks (aside form some capital ships, conventuional rockets just arent my thing aesthetically), their efficiency and range, reuseability (i find any fuel anywhere and im more or less starting out with a brand new craft), and the fact that i can use a single design to do more or less any mission to any location (provided i have the dV needed to get there). I also enjoy the higher difficulties with making a SSTO (rockets outside of forgetting struts or not having enough fuel/engines, and just a joke in terms of difficulty to make/use). But yeah, SSTOs from a pure efficiency standpoint arent all that great if you have no intentions to use atmosphere for gliding/abusing lift.

If you are very new to the game, i recommend starting with rockets (i went right to teh hardest thing, SSTOs and well took me a while to learn what works/doesnt work). if you are at all interested in spaceplanes though, start playing with atmospheric jets. if you like to fly those, SSTOs/spaceplanes are the same thing with some added complexity (although rapiers can give your SSTO an integrated engine). 90% of all spaceplanes/SSTOs are basically a conventional atmospheric jet with either an extra engine and fuel for it, or rapiers instead of turbojets and some LFO as well. RCS and monoprop is obviously needed for docking, and it is strongly reccomended to add at least 1-2 extra reaction wheels (cockpit is rarely enough). The reaction wheels help with both atmo flight, as well as in space (you need either RCS or reactionwheels to be able to turn in space (unless u use engine gimballing which is rather useless unless you dont care about being thrown off course during teh turning phase).

One more thing, just try every style, and stick to what you like. When i got the game, i played with rockets, i played with jets, and i found i liked aircraft alot more, so i decided to stick to aircraft, and then that led to me getting into SSTOs. I also developed a rather particular taste for certain looks (compact, micro fliers with stubby wings, dont know why i dislike massive wings), and thats what i stuck to.

[seaces]

Ok so I got that that from economical standpoint space plane I better at it becosue it is reusable. But since I am in this science only mode (went for this one since I just want to explore and do some science) I wonder are space planes limited much on what they can load as they cargo? I also like how they look but you know if the Space plane will only let me load some satellite that I could put in orbit with very simple rocket and rocket will take me less time to build....Anyway I might build them once I unlock all parts and maybe build some station around Kerbin with fuel supply and keep there parked my space planes that are easily moved from station to any other planet with required scientific equipment. BTW is it true that only Kerbin, Mun and MInimus have biomes? No biomes on other planet so no science points from going far away? Is there any mod that will add biomes and science points for other planets so that I have some nice incentive for bringing my equipment there?

[Ziff]

I personally don't think it makes sense to use SSTO spaceplanes beyond LKO. When engineering any space vessel, it's easier, simpler, and more efficient to design them to perform a specific task. My spaceplanes go from surface to LKO, and I have other vessels in orbit that are dedicated to operating from LKO to other locations. This is similar to the original STS proposed by NASA in the late 60s.

It depends on where you are going. Take a spaceplane to Lathe for instance, it has an atmosphere to run those air breathing engines. I think there is a mod that adds atmosphere to Duna and Eve as well, which makes certain designs viable on those planets as well.

[LethalDose]

Ok so I got that that from economical standpoint space plane I better at it becosue it is reusable. But since I am in this science only mode (went for this one since I just want to explore and do some science) I wonder are space planes limited much on what they can load as they cargo? I also like how they look but you know if the Space plane will only let me load some satellite that I could put in orbit with very simple rocket and rocket will take me less time to build....Anyway I might build them once I unlock all parts and maybe build some station around Kerbin with fuel supply and keep there parked my space planes that are easily moved from station to any other planet with required scientific equipment. BTW is it true that only Kerbin, Mun and MInimus have biomes? No biomes on other planet so no science points from going far away? Is there any mod that will add biomes and science points for other planets so that I have some nice incentive for bringing my equipment there?

The amount of payload you can put into orbit is limited by how well the spaceplane (or any other launch system, for that matter) is engineered.

At the current time, yes, only Mun, Minmus and Kerbin have biomes. However when 0.90 drops (which, again, will very likely be in the next 24 hrs), all planets will have biomes. Slightly over 100 in total.

It depends on where you are going. Take a spaceplane to Lathe for instance, it has an atmosphere to run those air breathing engines.

Sigh... yes... I know Laythe has an atmosphere that contains O2, air-breathing spaceplanes are useful there, too.

But if you think you needed to point this out, you're totally missing my point here: it's more efficient to use specialized craft for specific jobs. Please try understanding the point a poster is trying to make before nit-picking like this...

I think there is a mod that adds atmosphere to Duna and Eve as well, which makes certain designs viable on those planets as well.

You don't need a mod to add atmosphere to Duna and Eve. They have atmospheres. However, those atmospheres don't contain oxygen, so you can't run jet engines in them (OMG unless you save O2 in the intakes during take-off from Kerbin or Laythe). There may be a mod to add oxygen to their atmos, but that's pretty cheaty.

And technically you don't need a mod to use spaceplanes on the Duna and Eve. You can use rocket powered spaceplanes to take off using atmosphere for lift. Spaceplanes don't have to use air-breathing engines.

Edited December 15, 2014 by LethalDose

[Jouni]

2: SPs are more fuel efficient than rockets per payload mass.

3: SPs are safer and cheaper to land on bodies with atmospheres than rockets.

4: SPs are reusable - rockets tend to come apart on the way up/down as they drop stages.

A spaceplane is a rocket with wings and (possibly) a bit smaller engines. A rocket is a spaceplane without wings and (possibly) with a bit larger engines. As long as both types of craft use similar engines and similar staging, their operating costs, payload fractions, and precision landing capabilities are similar as well. Rockets are easier to build, because you only have to consider symmetry with them, and planes are more fun to fly, but otherwise both types of craft are essentially the same.

[Ziff]

Sigh... yes... I know Laythe has an atmosphere that contains O2, air-breathing spaceplanes are useful there, too.

But if you think you needed to point this out, you're totally missing my point here: it's more efficient to use specialized craft for specific jobs. Please try understanding the point a poster is trying to make before nit-picking like this...

I didn't miss your point at all. I was just pointing out to the OP who is asking about spaceplanes to begin with. Perhaps he is not aware that it's possible to create an SSTO capable of flying from Kerbin to Lathe, landing, and returning back. All without staging. It also depends on what your definition of "efficient" is. If efficient means saving money (which is what it always means to me, now) then you're going to want to take a SSTO along anytime you plan on returning to Kerbin. Or some sort of reusable lander.

On my Duna missions I typically launch 2 SSTOs to my orbital station. 1 carries a small transfer stage, the other carries the Duna lander. The lander and transfer dock in orbit, go to Duna, lander does it's thing and rendezvous back with the transfer stage. Both go back to Kerbin, and the SSTOs can land them again. All reusable, but the smaller craft are definitely designed specifically for the mission.

You don't need a mod to add atmosphere to Duna and Eve. They have atmospheres. However, those atmospheres don't contain oxygen, so you can't run jet engines in them (OMG unless you save O2 in the intakes during take-off from Kerbin or Laythe). There may be a mod to add oxygen to their atmos, but that's pretty cheaty.

And technically you don't need a mod to use spaceplanes on the Duna and Eve. You can use rocket powered spaceplanes to take off using atmosphere for lift. Spaceplanes don't have to use air-breathing engines.

Sorry, I was tired and misspoke. There is a mod that adds engines that are capable of using the other non oxygen or low oxygen gasses of Duna and Eve. It doesn't add oxygen to their atmospheres, and I'm not sure if those engines would function on Kerbin or if they have a switch mode on them or what. I'll have to find it.

[capi3101]

Ok so I got that that from economical standpoint space plane I better at it becosue it is reusable. But since I am in this science only mode (went for this one since I just want to explore and do some science) I wonder are space planes limited much on what they can load as they cargo?

I myself have been working on a plane that would deliver a '>Geschosskopf science bomb lander to orbit. Haven't quite gotten into orbit yet, though that's largely due to other things distracting me. I have gotten an asteroid-catching probe into orbit before using a spaceplane - which is significant in as much as the economics of rock catching missions in general are concerned (i.e. usually no return on the investment).

I'll recommend DocMoriarty's KSP Space Plane Construction and Operation Guide to you as an example of some of the things you can pull using spaceplanes as launch vehicles for various types of payloads; he uses his to put up space-station parts, and not tiny ones either. It focuses on use of the RAPIER engine and it's ever so slightly out of date at this point (by slightly I mean it was designed for 0.24.2 and he hasn't yet updated it for the changes in 0.25). So far the only differences I've seen is that the new Wing Connectors are functionally equivalent to Delta Wings, Shock Cone Intakes are equivalent to 1.2 Ram Intakes and 4 of the new Structural Intakes are roughly equivalent to a single Shock Cone Intake.

[Slam_Jones]

For me, spaceplanes started as a simple, cheap way to get small payloads to space. Now, I make them if I want a better-looking ship. But they still don't look as cool as ones I've seen on here...

[Kesa]

A spaceplane is a rocket with wings and (possibly) a bit smaller engines. A rocket is a spaceplane without wings and (possibly) with a bit larger engines. As long as both types of craft use similar engines and similar staging, their operating costs, payload fractions, and precision landing capabilities are similar as well. Rockets are easier to build, because you only have to consider symmetry with them, and planes are more fun to fly, but otherwise both types of craft are essentially the same.

You can put LFO engines on a plane as well as jet engines on rocket, and make quite efficient and fully reusable rocket SSTOs.

However, planes are more efficient than rocket precisely because they are rockets with wings and smaller engines. There are different paradignms for making planes, but I've seen very good SSTOs (Wanderfound ones I think), with TWR at launch barely above 1 or even under, because advanced jet engines are weak at see level. The lift provided by wings help it flying though. The equivalent rocket can not launch vertically without the help of extra expendable booster, or of heavier engines, making it less efficient.

[The_Rocketeer]

A spaceplane is a rocket with wings and (possibly) a bit smaller engines. A rocket is a spaceplane without wings and (possibly) with a bit larger engines.

No, a SP is not a rocket with wings. A SP is a aeroplane that can raise its apogee out of the atmosphere. This can be achieved with jet power alone, no rockets involved. Engine size also has nothing to do with it, even by your own standard.

As long as both types of craft use similar engines and similar staging, their operating costs, payload fractions, and precision landing capabilities are similar as well.

Anybody who assumes SP design will depend on rocket engines and staging has not appreciated the fundamental advantages of using an oxygen-rich atmosphere to reach space. If you flew a rocket-powered SP the way you fly a rocket, you'd find it's performance overall was lower because the wings would be dead-weight and subtract from max payload mass and TWR.

My basic point was, for a given payload mass, an optimised SP will always get it space for less fuel than an optimised rocket.

Precision landing is also easier and cheaper using a SP because you can use aerodynamics to glide towards your preferred landing site. If both designs are entitled to use parachutes, the SP can pick it's landing site at a lower speed, and corrections can be made by gliding and circling, potentially using no fuel. Rockets, by comparison, can only make corrections by thrusting. Without parachutes, it's even more fuel efficient, albeit marginally less precise on one axis (as in rolling distance), to land a SP. Think about it - Apollo aimed to land somewhere in the pacific, Soyuz lands in a desert region. Meanwhile the Space Shuttle lands on a runway.

Rockets are easier to build, because you only have to consider symmetry with them, and planes are more fun to fly, but otherwise both types of craft are essentially the same.

Rockets are easier to build, because they are basically a cockpit, a fuel tank and an engine. CoM and CoT are vertically aligned and CoL is basically irrelevant. SPs are harder because everything about them is more complicated. CoM, CoT and CoL all depend massively on where you designed them to be.

Rockets and planes are different to fly, but the extent to which they're 'fun' depends completely on the player. I've had great fun with rockets, jets, VTOLs, and all manner of hybrids.

Lastly, no. The two crafts are fundamentally different in engineering principle, performance capabilities and limitations, complexity of construction and piloting, and versatility. They are as different as dropping a stone and throwing a paper dart.

[panzer1b]

Ok so I got that that from economical standpoint space plane I better at it becosue it is reusable. But since I am in this science only mode (went for this one since I just want to explore and do some science) I wonder are space planes limited much on what they can load as they cargo? I also like how they look but you know if the Space plane will only let me load some satellite that I could put in orbit with very simple rocket and rocket will take me less time to build....Anyway I might build them once I unlock all parts and maybe build some station around Kerbin with fuel supply and keep there parked my space planes that are easily moved from station to any other planet with required scientific equipment. BTW is it true that only Kerbin, Mun and MInimus have biomes? No biomes on other planet so no science points from going far away? Is there any mod that will add biomes and science points for other planets so that I have some nice incentive for bringing my equipment there?

In terms of pure lifting capacity, id say that rockets are WAY easier to make, easier to fly, faster, and most of all have less part count. Splaceplanes that can lift upwards of 100 tons to orbit have so many wings, that the game will be painful to play due to lagginess. With procedural parts or upgrading to unity5, this is subject to change, but as it stands, it is impossible to make a spaceplane that can lift over 100t and not be made of like 500+ parts at a minimum (take a look at some long range cargo SSTOs, they are just so massive, and theyre more or less ocnstructed from nothing but wings, lagfest!).

this is the reason i stay away from atmospheric capital ships, yes they CAN be done, and they work nicely, but the half decent ones are just so massive, even my gaming rig cant handle over 500 parts reliably (i canb technically work with 1000ish, but lag starts at 400, and gets very annoying above 600)

[LethalDose]

... with TWR at launch barely above 1 or even under, because advanced jet engines are weak at see level...

Just a note: In the stock game (unlike IRL), thrust isn't altitude dependent. A turbojets thrust at sea level is equal to it's thrust at any other altitude. ISP changes with altitude.

[Empiro]

You make spaceplanes mainly for fun. Especially if you're playing with FAR, they present a unique challenge that you won't really get anywhere else in the game.

Even in career mode, I rarely will make a spaceplane other than for the challenge / fun. It takes me all of 10 minutes to design a rocket that can lift 40T, and another 5 minutes to launch it into space. If you use lots of disposable SRBs, it won't be that expensive either.

Even if I have a ready-to-go design for a spaceplane that can haul 40T to orbit, it will take me 10-15 minutes to climb and gather speed, and another 20-30 minutes to land it back at the KSC in what is a risky and stressful thing to do.