SSTO help please

[NateisKerbal]

I want to get into SSTO building, but I always end up using too much fuel. Any advice on how to use less fuel?

[bewing]

I will assume you mean spaceplane SSTOs. There are 3 basic enemies in SSTO building when it comes to fuel use.

1) drag
2) mass
3) inefficient flight profiles

Some rules for drag:

Don't use MK2 parts until you are much more experienced with SSTOs. MK2 parts have overabundant drag in most circumstances.
You need some drag at the very back of your spaceplane for stability, but you do not want it at the front. So any draggy radial stuff should be at the very back.
Use fairings if possible to enclose draggy stuff. Cargo bays don't quite work perfectly at the moment as regards drag.

Mass:

Remove everything from your spaceplane that you can. If your plane won't crash without that part, then remove it.
If you are comfortable enough, remove all RCS parts and monoprop.
Minimize the number of engines, especially airbreathing engines.
Use the smallest workable wheels, etc.

 

Flight profile:

Unless you are flying with a joystick, DON'T STEER. You can use the F key to lower the nose, but otherwise -- do not pitch, do not turn, don't bother rolling if you can avoid it. Every time you steer, you lose a huge amount of speed, and then you need to use a hell of a lot of fuel to regain that lost speed.

Just climb normally to 15 or 20km. Maybe break the sound barrier at about 5 or 6km altitude. And when you get to around 15km go to full throttle and push your airbreathing engines as far and fast as they will go.

[Foxster]

9 hours ago, NateisKerbal said:

I want to get into SSTO building, but I always end up using too much fuel. Any advice on how to use less fuel?

Can you post a picture of the craft you are currently struggling with?

[NateisKerbal]

8 hours ago, Foxster said:

Can you post a picture of the craft you are currently struggling with?

http://steamcommunity.com/sharedfiles/filedetails/?id=1161264971

It's hard to fly, but has a lot of delta v.

[NateisKerbal]

15 hours ago, bewing said:

I will assume you mean spaceplane SSTOs. There are 3 basic enemies in SSTO building when it comes to fuel use.

1) drag
2) mass
3) inefficient flight profiles

Some rules for drag:

Don't use MK2 parts until you are much more experienced with SSTOs. MK2 parts have overabundant drag in most circumstances.
You need some drag at the very back of your spaceplane for stability, but you do not want it at the front. So any draggy radial stuff should be at the very back.
Use fairings if possible to enclose draggy stuff. Cargo bays don't quite work perfectly at the moment as regards drag.

Mass:

Remove everything from your spaceplane that you can. If your plane won't crash without that part, then remove it.
If you are comfortable enough, remove all RCS parts and monoprop.
Minimize the number of engines, especially airbreathing engines.
Use the smallest workable wheels, etc.

 

Flight profile:

Unless you are flying with a joystick, DON'T STEER. You can use the F key to lower the nose, but otherwise -- do not pitch, do not turn, don't bother rolling if you can avoid it. Every time you steer, you lose a huge amount of speed, and then you need to use a hell of a lot of fuel to regain that lost speed.

Just climb normally to 15 or 20km. Maybe break the sound barrier at about 5 or 6km altitude. And when you get to around 15km go to full throttle and push your airbreathing engines as far and fast as they will go.

http://steamcommunity.com/sharedfiles/filedetails/?id=1161264971

This is the craft I'm using. Thank you for the help!

[Spricigo]

8 hours ago, Foxster said:

Can you post a picture of the craft you are currently struggling with?

And a brief description of your objectives. 

[luizopiloto]

To design spaceplane SSTOs you have to focus on 3 things:
Aerodynamics, TWR and Balance...
Less drag is the best... put all radially attached parts inside a fairing or cargobay... radiators have to be outside, but it won't create much drag depending of placement...
The only problem is when it comes to landing... the thing will not loose enough speed for a safe landing...

TWR to achieve speeds above 1200m/s  at 12.000m altitude... But it have to be the right ammount of engines... too much and you will lose Δv due to dead wight in space...
Air breath engines like Rapiers (best for SSTOs) and TurboJets gains more power at supersonic speeds, but you need sufficient power to reach such speeds...

Balance is crucial... weight distribution is a key thing to make a craft fly right at any situation...
the craft must retain it's attitude w/o control surfaces help... because any deflection created by control surfaces, adds drag... and when it comes to de-orbit, the angle of attack needed to do it safely (usually 30°) will not be possible to sustain if the craft is not balanced properly... CoM and CoL relation is the basic variables... but they change because Drag and Bodylift changes this relation depending of the angle of attack... and the editor don't show you this info.

The best base concept I've found for SSTOs is the "Skylon" design... because CoM, CoL, Drag and Bodylift relation remains the same at any situation...

[Foxster]

2 hours ago, NateisKerbal said:

http://steamcommunity.com/sharedfiles/filedetails/?id=1161264971

This is the craft I'm using. Thank you for the help!

One of the major challenges with that craft is drag. That is going to really suck up all your dV. 

It's not easy to tell but you have some odd joint/adapter thing going on where the the round parts near the front meet the mk2 stuff. Then you have the 1.25/2.5m adapter thrown in there that will be pretty draggy - better to try to stick to all 1.25m stuff. Then you have a bunch of other stuff like the big reaction wheels, solar panels, batteries, and lights that will be draggy. Plus some extra wings and control surfaces. 

One pro tip for SSTOs (and pretty much any KSP craft): It's not what you add that will fix a craft, it's what you take away. 

 

Edited October 7, 2017 by Foxster

[Geschosskopf]

On 10/6/2017 at 6:20 PM, NateisKerbal said:

I want to get into SSTO building, but I always end up using too much fuel. Any advice on how to use less fuel?

I leave the technical details of HOW to make an SSTO spaceplane work to those who devote considerable time to that.  But the best advice I can give you is, don't do it, UNLESS you're planning your whole game around them.  In anything less than RSS games, they just don't make any practical sense.  The reasons for this are as follows:

• Spaceplanes can't carry much payload in terms of volume able to fit in the cargo bay.  Thus, they always lag WAY behind rockets in carrying usefully large loads.  By the time you've unlocked the tech necessary for a spaceplane to get a Mun probe to LKO, you'll have rockets that can throw entire colonies to Laythe.
• The main argument in favor of doing spaceplanes is that they're cheaper than putting the same payload into LKO compared to a rocket.  This is quite true, in terms of in-game money.  But there are 2 counter arguments:  1) in-game money isn't the only currency, there's also you personal time (see below); and, 2) by the time you've unlocked the tech to make spaceplanes able to get to LKO with a marginally usefully sized payload without TOO much (by spaceplane standards) fuss, you're so rich you don't need to save the small amount of money spaceplanes can give you.
• The more efficient the spaceplane, the longer it takes to get to LKO.  Like 20-30 minutes per launch, compared to 3-5 minutes for a rocket.  This means that if you go spaceplane, you get much less done per play session, which makes a HUGE difference if you can only spend 1-2 hours playing KSP at a time.
• Being able to get a usefully large spaceplane to LKO reliably even in 20 minutes takes MANY, MANY hours of cold sober design tweaking, separated by many 20-30 minute intervals of watching the previous version fail, so you  know what to tweak next time (the design itself or the ascent profile).  OTOH, you can whip together a rocket to lift the same payload in 10-15 minutes even when snot-slinging drunk, and it will work the 1st time.  So again, if you have limited playtime, spaceplanes are black holes consuming all your time.
• For all this effort, all you get is something that can get a relatively small payload to LKO compared to what a rocket of similar tech level can do.  Doing any more than this with a spaceplane simply illustrates how small the stock KSP solar system is compared to real life.

So, bottom line, the less time you have for KSP, the less sense it makes to mess around with spaceplanes, UNLESS that's your total focus.

[bewing]

14 hours ago, NateisKerbal said:

http://steamcommunity.com/sharedfiles/filedetails/?id=1161264971

This is the craft I'm using. Thank you for the help!

Yeah, I looked at your craft. I agree that your problem with running low on fuel is that the thing has too much drag, because it has too many parts. If you were to simplify your plane a lot, I think you would find it performs better with each simplification.

 

[NateisKerbal]

19 hours ago, Foxster said:

One of the major challenges with that craft is drag. That is going to really suck up all your dV. 

It's not easy to tell but you have some odd joint/adapter thing going on where the the round parts near the front meet the mk2 stuff. Then you have the 1.25/2.5m adapter thrown in there that will be pretty draggy - better to try to stick to all 1.25m stuff. Then you have a bunch of other stuff like the big reaction wheels, solar panels, batteries, and lights that will be draggy. Plus some extra wings and control surfaces. 

One pro tip for SSTOs (and pretty much any KSP craft): It's not what you add that will fix a craft, it's what you take away. 

 

I added the converter for more fuel, but it must add too much drag. I'll take away the panels and reaction wheels.

[AeroGav]

4 hours ago, NateisKerbal said:

I added the converter for more fuel, but it must add too much drag. I'll take away the panels and reaction wheels.

Converters are actually quite low drag, provided the front and rear attachment nodes are  hooked up to something with an attach node of the same diameter.

This is actually rule number one for low drag.  All axial / end on attach nodes must be hooking up to parts with an attach node of same diameter.   Use size adapters when converting from parts of one diameter to another.    As far as I can see you appear to be complying with this.

 

However, it looks like you got a 2.5m quad adapter behind the cockpit, with two mk2 fuselages attached on the top and bottom nodes and mk1 fuselages on the left/right.

That is a lot of mk2 fuselage, and mk2 fuselage have horrible drag characteristics.  It is in fact very difficult to design a good mk2 spaceplane.

You would be better off just keeping to a 2.5m fuselage all the way to the back, then have your tri/quad adapter followed by the engines.  2.5m parts are best for drag, 1.25m and mk3 are ok,  mk2 are bad. 

If you need more engines, just just type B nose cones to radially attach around your main stack.

The game provides an easy way to compare which parts are good and bad for drag.   Press ALT F12 then go to Physics, Aero and tick the box that says " display aero data in action menus".

Right click on some parts of your craft , pin the menus in place, go flying around and take screenshots.   Since all the parts are at the same airspeed, altitude and angle of attack, you'll get a pretty good comparison of what makes the most drag.

These days I keep my fuselage parts to a minimum, and try to keep most of my fuel in the wings.

[Spricigo]

15 hours ago, Geschosskopf said:

I leave the technical details of HOW to make an SSTO spaceplane work to those who devote considerable time to that.  But the best advice I can give you is, don't do it, UNLESS you're planning your whole game around them.  

I disagree,  spaceplanes are useful for some tasks.  Using spaceplanes when they are the right tool (or at least a good one) for the task at hand make sense. Using spaceplanes despite better options available can only be justified by rule of cool/it's a challenge. 

Also,  while the drawbacks you pointed are real only in extreme cases it will be that big issue you describe.  

[Geschosskopf]

50 minutes ago, Spricigo said:

I disagree,  spaceplanes are useful for some tasks.  Using spaceplanes when they are the right tool (or at least a good one) for the task at hand make sense. Using spaceplanes despite better options available can only be justified by rule of cool/it's a challenge. 

Also,  while the drawbacks you pointed are real only in extreme cases it will be that big issue you describe.  

To each his own.  I didn't say spaceplanes were useless, just that they entail a huge amount of effort for what you get out of them, compared to rockets, so that it's usually better from a how-much-overall-game-progress-you-make-before-bedtime POV to avoid them unless you're just into spaceplanes.

Personally, I find spaceplanes only worth the trouble very late in the game, once I've got the RAPIER.  Then it's not too hard to make a small (2-8 seats) crew shuttle to LKO, and such things are fast enough not to eat too much time flying them there.  But prior to having the RAPIER, I find spaceplanes way more trouble than they'r worth, and in the meantime cheap, simple rockets work for crew shuttles.  And even with the RAPIER, I don't find their practicality very high compared to rockets.  Thus, I tend not to unlock the RAPIER until I've run out of other things to unlock that are more useful on a day-to-day basis, because an SSTO crew shuttle is not high on my list of priorities.  But it IS way cooler than a rocket  

[bewing]

I like TSTO spaceplanes. You get the fast ascent of a rocket, a low cost to orbit when using a handful of kickbacks for your first stage, and all the landing benefits of a spaceplane.

And I don't bother carrying cargo on spaceplanes. Just take the spaceplane itself wherever you want to go to do the mission.

Edited October 9, 2017 by bewing

[Spricigo]

26 minutes ago, Geschosskopf said:

Personally, I find spaceplanes only worth the trouble very late in the game, once I've got the RAPIER.  Then it's not too hard to make a small (2-8 seats) crew shuttle to LKO, and such things are fast enough not to eat too much time flying them there. 

That is one of the niches that I think SSTO spaceplanes perform well even whitout the rapier. I have a resonable 4-seat SSTO spaceplane with 1whiplash+3spark, other people had designed good ones with panthers and terriers.

IMHO the problem is when people overdo the 'optimization' and end with a craft that is cheap to operate but also a PITA with impratical long time to orbit and very sensitive to the smallest piloting error. Or insist to use a spaceplanes in long interplanetary travels  "becasue the efficiency", failing to notice that above 30km the plane part of the craft is just deadweight.* For most part planes are like any other tool in the toolbox, good for some tasks but not for all

 

*I know there are player out there that simple love spaceplanes. Lets be clear: i see no problem in using spaceplanes because of likes, or to challenge yourself. My gripe its to people that, instead of assuming that they use spaceplanes just because they like, try to invoke advantages that are minimal or even non-existent in their designs. The worse part is they often ignore the advantages their designs really have.

[Spricigo]

26 minutes ago, bewing said:

I like TSTO spaceplanes. You get the fast ascent of a rocket, a low cost to orbit when using a handful of kickbacks for your first stage, and all the landing benefits of a spaceplane.

I dont even bother to design mine to have "all the landing benefits of a spaceplane" , It just need to allow me to bring it to the runaway and not break anything .

[Geschosskopf]

34 minutes ago, bewing said:

I like TSTO spaceplanes. You get the fast ascent of a rocket, a low cost to orbit when using a handful of kickbacks for your first stage, and all the landing benefits of a spaceplane.

And I don't bother carrying cargo on spaceplanes. Just take the spaceplane itself wherever you want to go to do the mission.

The Dream-Chaser idea IMHO is the best way to deal with spaceplanes.  Get them up like rockets, bring them home like planes, best of both worlds.

I myself don't to interplanetary spaceplanes by themselves, simply as a personal taste thing.  If I need a spaceplane at another planet, I'll lug it out there with a conventional rocket.  This is a tip of the hat to the difference in scale between real life and stock KSP solar systems.  And also because spaceplanes tailored to anywhere but Laythe won't fly on Kerbin anyway

 

12 minutes ago, Spricigo said:

That is one of the niches that I think SSTO spaceplanes perform well even whitout the rapier. I have a resonable 4-seat SSTO spaceplane with 1whiplash+3spark, other people had designed good ones with panthers and terriers.

Chacun à son goût.    Without a RAPIER, I myself find SSTO spaceplanes more trouble than they're worth, although I'll go Dream-Chaser before RAPIER when I'm in that sort of mood  But usually I'm not, and my airplane tech usually lags WAY behind my rocket tech anyway.

 

[juanml82]

Start small. Stick to 1.25m parts. Don't add solar batteries. Get into sandbox if you aren't there already, add a service bay and stick rtgs and one battery inside for electric power. As for the rest, try something with a shock cone in the nose, an inline cockpit, use the Big-S wings for liquid fuel storage and add enough LF and LFO tanks to make it to orbit. Try to keep the total weight around 15-20t and use one single rapier engine. Don't add rcs.

Check the tutorials on spaceplane building as well: CoL (use the correct CoL mod) behind the CoM. You should also try to keep the wet and dry CoM as close as possible, but that won't happen with the design I've just told you about. Use the RCS Build aid mod to check the dry CoM. Give the wings a small incidence (rotate them upwards 5°) and don't put your landing gear on the wings.

Once you have that spaceplane in orbit, then you can begin to scale them up with MK3 or MK2 parts. Your main concern should be minimizing drag and making sure the plane remains balanced after the fuel is expended. dV comes later, because you can always add another fuel tank inline with your existing tanks, although eventually you'll have to add more engines to have enough power to break the sound barrier.

[AeroGav]

4 hours ago, Geschosskopf said:

And also because spaceplanes tailored to anywhere but Laythe won't fly on Kerbin anyway

Given that only Duna, Eve and Laythe have atmospheres, I'm not sure what you mean ?     A stock Eve spaceplane isn't possible,  but Laythe is less demanding than Kerbin in all respects.   A Duna spaceplane needs large wing area/robust gear/vernor thruster lift engine system,  but these features do not prevent it SSTO from Kerbin.   For example,   this extreme STOL aircraft (the rules of the challenge it was built for forbade lift engines and brake chutes)  can take off and land horizontally from the roof of the VAB.   It still goes to orbit !

https://kerbalx.com/AeroGav/stol

Takeoff video here.   If you follow the link to the KerbalX page, you get the landing video, which is shorter, and more spectacular.

Spoiler

 

 

 

 

df

5 hours ago, Spricigo said:

IMHO the problem is when people overdo the 'optimization' and end with a craft that is cheap to operate but also a PITA with impratical long time to orbit and very sensitive to the smallest piloting error

 

On 08/10/2017 at 5:47 AM, Geschosskopf said:

The more efficient the spaceplane, the longer it takes to get to LKO.  Like 20-30 minutes per launch, compared to 3-5 minutes for a rocket.

This criticism is thrown at my designs a lot by the likes of yourself, @mk1980 and others.        The thing is, my 25-30 minute to orbit designs have low drag,  and still have over twice as much thrust as drag at all stages of the flight.     Thus, they are equivalent to the rocket with the optimal 2:1 TWR.   The goal is not to get to orbit with the lowest TWR, which would be unforgiving to fly as the tiniest error would cause failure and utterly pointless because of all the losses.    The object is to find the best compromise between minimising losses and maximising fuel/payload fraction.

In terms of flight profile,  they're designed to be flown within a degree or two of prograde at all times.  That is where the aerodynamic forces push the nose anyway. Ideally,  you should stop climbing when accelerating supersonic and not climb above 22km till you've gotten all possible speed out of airbreathing mode.    But with my interplanetary designs, you can just set prograde on the runway , start all the engines and let them do their own thing, it will still get to space, though you won't have as much delta V left over and might melt off the nosecone.    OTOH, that "method" can save 10 minutes compared to trying to be as efficient as possible.

In a stock scaled solar system, the thing to remember about the "time" argument is that landing and docking stuff takes ages.       So flying up a crew ssto or using a big cargo ssto to launch an interplanetary ship,  means you either have to perform a rendezvous/docking  or   land an additional vessel at KSC.        An interplanetary SSTO with mining gear onboard, like this -

https://kerbalx.com/AeroGav/Starsailor

might need 25 minutes to orbit,  but can go direct to Duna.   Land, refuel , then fly straight to the Jool system or Eeloo.   

If I was really in a hurry and wanted to skip this refuelling stop on Duna,   then I'd probably build an airplane with extra jet engines and fuel tanks carried under the wings that can be decoupled on the way up - can easily get enough delta V to make a straight shot to anywhere that way.

9 hours ago, Geschosskopf said:

Personally, I find spaceplanes only worth the trouble very late in the game, once I've got the RAPIER.  Then it's not too hard to make a small (2-8 seats) crew shuttle to LKO, and such things are fast enough not to eat too much time flying them there.  But prior to having the RAPIER, I find spaceplanes way more trouble than they'r worth, and in the meantime cheap, simple rockets work for crew shuttles.  And even with the RAPIER, I don't find their practicality very high compared to rockets.  Thus, I tend not to unlock the RAPIER until I've run out of other things to unlock that are more useful on a day-to-day basis, because an SSTO crew shuttle is not high on my list of priorities.

With default difficulty settings there is no point re-using anything.     Component costs are very cheap compared to the building upgrade costs,  so just grab a load of satellite contracts and grind out the cash.    I like to play custom difficulty games where the "funds reward" is reduced to 30%, as are the "funds penalties".  In other words, you only get 30% as much money for each contract, but the building upgrades are cheaper.     However, you have to re-use at least some of your vessel or you'll loose money on every contract.

 

5 hours ago, Geschosskopf said:

Chacun à son goût.    Without a RAPIER, I myself find SSTO spaceplanes more trouble than they're worth, although I'll go Dream-Chaser before RAPIER when I'm in that sort of mood  But usually I'm not, and my airplane tech usually lags WAY behind my rocket tech anyway.

"To each his own".    This is true.      You will always default to the rocket option when considering a challenging mission.   I 'll design a multi stage spaceplane, with droppable jet engines and fuel tanks,  because for me that is a surer way of getting there than a large and complex rocket i am inexperienced in building.   

Jool 5 motherplane - https://kerbalx.com/AeroGav/Steven-Tylo

Spoiler

Contrary to popular belief, it is symmetrical.  Also,  3 different colour exhaust plumes.  Four when you fire up the nukes to go supersonic.

Bombs away Tank Separation

Whiplash separation is a bit more violent,  not even Jeb likes it

But they all lived happily ever after.  Tylo lander on display.  The front used to contain a lounge with Kerbal furniture mod, but removed it since not many people install that.  There was also a rover, which proved less stable on terrain than the airplane itself.   So now there's a CRG100 bay worth of empty space up front...

 

The thing is,  when I bought this came i'd already spent maybe 20 or 30 hours in microsoft flight simulator,  and i knew from a book I read at school (about gliding) that best lift/drag ratio is at about  5 degrees to the airflow, so i managed to get a spaceplane to orbit before i figured out how to build a rocket that would gravity turn properly (and not have insane staging).

[Geschosskopf]

5 hours ago, AeroGav said:

Given that only Duna, Eve and Laythe have atmospheres, I'm not sure what you mean ? 

I was mostly thinking of Tekto in OPM.  A spaceplane for that place simply cannot have anywhere near the wing area or thrust needed to fly at Kerbin.  At Duna, it's the other way around.  A Kerbin spaceplane on Duna is simply a rocket flying on pure thrust---the jets do nothing and the wings don't do enough to notice.  

 

5 hours ago, AeroGav said:

This criticism is thrown at my designs a lot by the likes of yourself, @mk1980 and others.     

I wasn't criticizing your designs.  They're very good, way better than what I have the time and patience to make and use    I was instead replying to the OP, who "wants to get into SSTOs".  I think it's important for such folks to know up front about the huge time investment spaceplanes require, and what sort of capabilities you end up with after making all that effort.  This is definitely not for everybody.  A minority of players, such as yourself, really enjoy doing spaceplanes, get quite good at them, and learn how to make the most of what they can do.  The majority of players, including myself, find them way more trouble than they're worth.  This is just the nature of the beast.

[Spricigo]

7 hours ago, AeroGav said:

In a stock scaled solar system, the thing to remember about the "time" argument is that landing and docking stuff takes ages.       So flying up a crew ssto or using a big cargo ssto to launch an interplanetary ship,  means you either have to perform a rendezvous/docking  or   land an additional vessel at KSC.        

Three points:

 1.The comparison is not only SS interplanetary spaceplane vs SSTO Spaceplane plus single stage interplanetary ship. 

2.Docking is takings ages either for lack of skill or lack of proper design.  The same way you developed the skill for piloting/design spaceplanes the techniques fot docking can be developed. 

3.If, for similarly priced alternatives,  it takes 5-10mins to land the auditional craft and it cuts 10-15min in the way up (with the advantages of a much lighter but equally capable vessel for the space part of the trip) there is no question I'd take the deal. 

 

 

7 hours ago, AeroGav said:

The object is to find the best compromise between minimising losses and maximising fuel/payload fraction.

And  there remain the divergence.  We will have different methods to evaluate 'efficiency', Thing that are very important to me can be almosy irrelevant for you and vice versa. 

In any case, as I said before, no problems if our tastes differ. As long we don't argue which taste is 'best'.

[Spricigo]

2 hours ago, Geschosskopf said:

This is definitely not for everybody.  A minority of players, such as yourself, really enjoy doing spaceplanes, get quite good at them, and learn how to make the most of what they can do.  The majority of players, including myself, find them way more trouble than they're worth.  This is just the nature of the beast

If you have any good evidence to back up that claim, I'm worried how did you got it.

Hopefully that's just an assumption,  based in how do you play,  maybe a few friend and whatever people say on the forums. 

[Geschosskopf]

3 hours ago, Spricigo said:

If you have any good evidence to back up that claim, I'm worried how did you got it.

Hopefully that's just an assumption,  based in how do you play,  maybe a few friend and whatever people say on the forums. 

There have been a number of polls on spaceplane usage over the years.  There is also scads of observational data from just watching the forum, especially "What Did You Do in KSP Today?" and Mission Reports.  Also, all the questions from folks who've been playing quite a while but now want help with spaceplanes.

All this adds up to the following generalizations:

• Everybody tinkers with Kerbin-based SSTO spaceplanes at least once
• A fair number of folks, although still definitely a minority of the population, use the occasional small, Kerbin-based SSTO spaceplane for a crew shuttle to LKO
• These same folks tend also to use an SSTO spaceplane when they go to Laythe, although just to get Kerbals up and down.  They explore with non-space airplanes
• Only a handful make Kerbin-based SSTO spaceplanes their main, or even a frequent means, of getting to space
• The main reason for this is the time-sink, and then the rather limited capabilities of the things as cargo-haulers.

This all is way more the case today than it was back when intake-spamming and other long-gone aspects of KSP aero were still things.  Back in those ancient days, it was pretty easy to make an SSTO spaceplane without investing much time in it than for a rocket, and it could get to space much quicker, so the whole thing wasn't such a time-sink.  Thus, pretty much everybody used them fairly often.

Look, I'm not casting aspersions on spaceplanes in general, nor on anybody who uses and advocates them.  Spaceplanes have a huge coolness factor and I greatly respect all the time spaceplane experts have invested to get so good at making and using them.  There's no way NOT to be greatly impressed by such devotion to craftsmanship.  But the fact remains that for most players these days, their initial attraction to spaceplanes for the coolness factor is soon overcome by the realization that spaceplanes are like mastering a musical instrument.  You'll never really get anywhere of significance unless you're willing to devote all your leisure time to them.  This turns off most potential users, which is why spaceplane devotees are the minority.  Just like great musicians are the minority.   Don't take that as an insult, take it as a compliment.

[AeroGav]

This is also marketed as a space game.     The OP was successful in building rockets and now wanted to try his hand at aircraft.

Most people come to this game as fans of amateur rocketry, space history , science fiction.   The number who come with a back ground of plane spotting/flight sims is probably much smaller.    However if you are a plane spotter/flight simmer and have never given any thought to how a rocket works before,   it can actually take longer to get a working sandbox rocket than a working sandbox spaceplane.