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Roflcopterkklol

No more SSTO's

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This graph was taken from the Skylon manual off the Reaction Engines website. Blue is the flight profile they claim the Skylon will need to follow, green is what most space-planes in KSP used to follow, and red is the current best flight profile to avoid blowing up/moving through air best. So please tell me how this new heating/aero model makes any sense.

sUTzTW2.png

http://www.reactionengines.co.uk/tech_docs/SKYLON_User_Manual_rev1-1.pdf

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This graph was taken from the Skylon manual off the Reaction Engines website. Blue is the flight profile they claim the Skylon will need to follow, green is what most space-planes in KSP used to follow, and red is the current best flight profile to avoid blowing up/moving through air best. So please tell me how this new heating/aero model makes any sense.

http://i.imgur.com/sUTzTW2.png

http://www.reactionengines.co.uk/tech_docs/SKYLON_User_Manual_rev1-1.pdf

I note that "After take-off the vehicle climbs and accelerates on its predetermined trajectory for 694 seconds (approx 11½ minutes), by which time it has reached an altitude of 28.5 km and a speed of Mach 5.14." At 28km altitude the craft is moving at 1500m/s, give or take, at which point it switches over to closed-cycle mode and ascends. In KSP terms, the atmospheric height is probably somewhere around 24km, maybe 23km. Once the higher-thrust mode kicks in the craft rises quickly, gaining some ten km in about a minute. In KSP terms, that puts you at about 30km or so, well into the third atmosphere band where atmospheric heating is much less. Furthermore, you should actually be doing that transition much faster since launches in KSP are so much faster to begin with.

When Skylon switches over to closed-cycle mode it still has some 7~8km/s of burn left before orbit. KSP, in constrast, using the flight profile you have outlined with an expected speed of 1500m/s at 24km, only requires you to expend another 1500m/s or so. That's only half of your delta-V as rocket fuel. If you were following Skylon's flight profile scaled properly, you'd instead be flying at about 500m/s (give or take) at 24km altitude before igniting your closed-cycle engines and rapidly climbing out of the atmosphere that is heating your craft. in other words, if you want to use a fictional* spaceplane as your reference, use that reference correctly.

E: It's worth pointing out that KSP's atmospheric heating is scaled to actually matter. That is, if you modeled it directly off of Earth's atmospheric model you literally wouldn't care about heating at all because of the slow speeds the craft move at. Seriously, the fictional Skylon moving at its fastest air-breathing mode is about 68% of LKO orbital velocity (about 2.2km/s), as opposed to 19% of LEO orbital velocity (7.8km/s). We've got it very easy here on Kerbin.

*Fictional as in it doesn't exist.

Edited by regex

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Pre-1.0 you could build purely for aesthetics and do silly things like stack tens of wings.

To achieve a shape that was decidedly more aerodynamic looking than the now optimal configuration. Don't be so judgmental.

Now you have to at least try for an aerodynamic shape.

That's the point, trying to build something that looks aerodynamic, using wings to build a "shell", is actually punished.

Is it perfect? No.

Exactly. It's a step in the right direction but improvements are needed.

Go talk to ferram4 about compromises in oldFAR for the purpose of trying to figure out the shape of whatever crazy contraption the user made because KSP let them. KSP uses some of those same techniques, as I understand it. And if you're still mad about it, check out nuFAR, which voxelizes the vessel into a single shape. Then you'll get a real taste of "limited creativity"; KSP is at least kind enough to treat your wing shape differently based on speed, which gives you much more leeway in design.

We need the tools to make aircraft look less like tubes with wings and more like the high speed "darts" envisioned by actual engineers*, or we need an aerodynamic model that allows us the creative space to 'fix' the current optimal look of a spaceplane without punishing us. The previous aero model didn't exactly favour wing part count either, but it was compensated for by the overpowered jet engines. Now all we need is a way for drag to not drastically increase as soon as we stack wings even in sensible ways.

*sr-72-og.jpg

You speak of creativity as if it is something bad, yet the core of KSP is building your own rockets and spaceplanes. As a game, there should be a range of viable designs and approaches, from frankencraft to finely crafted darts. Even if that does not translate into the most realistic approach. If a player desires 100% realism, then perhaps that person should turn to, you know, a real space program or use any of the realism mods available. The irony being, of course, that the current aero model isn't particularly realistic with respect to part - or, specifically, wing - placement.

Edited by Aanker

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You speak of creativity as if it is something bad
Uhm, no. I speak of creativity in the same manner as the people who think procedural parts are somehow uncreative: Use the tools you have to make something you like within the limits given. The limits have changed but your expectations have not.
yet the core of KSP is building your own rockets and spaceplanes.
And that hasn't changed one iota.
As a game, there should be a range of viable designs and approaches, from frankencraft to finely crafted darts.
There are quite a wide variety of viable craft shown in this thread alone, I don't KSP is lacking in that department.
If a player desires 100% realism, then perhaps that person should turn to, you know, a real space program or use any of the realism mods available.
pot ...
The irony being, of course, that the current aero model isn't particularly realistic with respect to part - or, specifically, wing - placement.
meet kettle. Seriously. If you want the shape of your craft to be analyzed and treated as a complete object you should check out nuFAR, because KSP and oldFAR deal with parts individually, which is very hard to program interaction for given just what KSP allows.

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Honestly I don't think SSTO's have ever been easier, it took me an hour to get this one into orbit and docked to my transport there. No payload capacity but not needed, already have a larger SSTO easily capable of 5T payload. I could never get an SSTO working in old stock, only in FAR. I think this is much easier, you just have to bring a lot more LFO. Using the offset tool I clipped an FLT800 into the body of this craft.

<blockquote class="imgur-embed-pub" lang="en" data-id="a/JUEw9"><a href="//imgur.com/a/JUEw9">SSTO</a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>

* Don't know how to get it to embed, album is here.

** Oh yeah, RCS thrusters are clipped into the body, as are RCS tanks, to protect them and for better appearance. The new offset tool is an absolute godsend. Don't like how far the Landing gear sticks out? Offset to clip it into the body. :)

Edited by Halo_003

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Uhm, no. I speak of creativity in the same manner as the people who think procedural parts are somehow uncreative: Use the tools you have to make something you like within the limits given. The limits have changed but your expectations have not.

Procedural wings would be one solution to this problem, so I don't see the issue you're getting at.

And that hasn't changed one iota.

There are quite a wide variety of viable craft shown in this thread alone, I don't KSP is lacking in that department.

The problem is that the new aero model simply, arbitrarily and bluntly favours less wing parts. As a replacement, we have been given large wings which don't blend well with the other parts and can only really be used when they fit the design perfectly. Many of us (me included) have previously used wing parts to smooth out what would otherwise look as a 'frankenplane' or a not very aerodynamically looking spaceplane. These new restrictions have only negative effects, and they are completely unnecessary, and they can be addressed in future patches without a substantial part of the spaceplane builders having to resort to mods (some of which, by the way, aren't even supported on my x64 system).

pot ...

meet kettle. Seriously. If you want the shape of your craft to be analyzed and treated as a complete object you should check out nuFAR, because KSP and oldFAR deal with parts individually, which is very hard to program interaction for given just what KSP allows.

Interesting misinterpretation of what I was getting at: the wing restriction doesn't add realism, it doesn't add fun, it doesn't improve the creative aspect of the game, and it certainly doesn't "balance" wings - so why defend it? Why not just ask Squad to fix this aspect of their new aero model. I like everything else about the aero physics, but this is just sad.

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Procedural wings would be one solution to this problem, so I don't see the issue you're getting at.
You've missed some of the arguments against procedural parts, no biggie. The claim being that restrictions and limits on parts make one more creative.
The problem is that the new aero model simply, arbitrarily and bluntly favours less wing parts. As a replacement, we have been given large wings which don't blend well with the other parts and can only really be used when they fit the design perfectly. Many of us (me included) have previously used wing parts to smooth out what would otherwise look as a 'frankenplane' or a not very aerodynamically looking spaceplane. These new restrictions have only negative effects, and they are completely unnecessary, and they can be addressed in future patches without a substantial part of the spaceplane builders having to resort to mods
Can they? Can you show us how in a mod without breaking all the good things about KSP's new aero?

Personally I'm quite excited by the prospect of less wings meaning more for the craft because the old aero system favored stacking and clipping a god-awful amount of parts into a craft in order to get any meaningful amount of lift or control out of the craft.

some of which, by the way, aren't even supported on my x64 system
If it's Windows then let's just say that x64 is literally some dead dictator from Germany and mod authors got blamed for everything they didn't do so there's a reason no one wants to cater to anyone's usage thereof.
it doesn't add fun
Subjective.
it doesn't improve the creative aspect of the game
Subjective.
and it certainly doesn't "balance" wings
Subjective.
so why defend it?
I'm not defending the wing (building) system as I think is is god-awful terrible (procedural wings in stock would be a god-send), rather I am defending the implementation of aerodynamics as it currently stands insofar as what you want to see is programmatically very difficult. Again, I point you to the compromises that NEAR/FAR have had to use in order to handle parts-based aerodynamics. ferram4's nuFAR will deal with aerodynamics in a vessel-oriented manner, which is probably better for your purposes.

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Even if you take the scaling issue into account, it doesn't explain why the Skylon's ascent profile allows it to more or less cruise at altitude before engaging it's rockets compared to KSP SSTOs needing to have a linear ascent profile. I find it ridiculous that I can point my craft at a 30 degree pitch, set my engines to full throttle and just watch the plane take itself to a 90km apoapsis to circularize.

It's not to mention that the new aero system encourages people to make monstrously large aircrafts the size of submarines to get to orbit (because it's contradictorily easier), then it tells me that the aero still needs more work.

Edited by Levelord

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Even if you take the scaling issue into account, it doesn't explain why the Skylon's ascent profile allows it to more or less cruise at altitude before engaging it's rockets compared to KSP SSTOs needing to have a linear ascent profile. I find it ridiculous that I can point my craft at a 30 degree pitch, set my engines to full throttle and just watch the plane take itself to a 90km apoapsis to circularize.
Well, the planet you're taking off from is literally the size of Ceres and has an orbital velocity 150% of the Skylon's cruising speed at altitude, what did you expect?
It's not to mention that the new aero system encourages people to make monstrously large crafts the size of submarines to get to orbit, because it's contradictorily easier, then it tells me that the aero still needs work.
When you have to carry more fuel mass to get to orbit, craft get bigger, nothing wrong with that. It's interesting that rockets got smaller while spaceplanes got bigger, although it looks like Wanderfound, or hell, even the OP, doesn't have any issues with making small craft.

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Well, the planet you're taking off from is literally the size of Ceres and has an orbital velocity 150% of the Skylon's cruising speed at altitude, what did you expect?

You just said yourself in a previous post that the lower velocity is to scale with Kerbin's smaller size, and now you're comparing the velocity to the Skylon's saying it's 150% of its cruising speed while ignoring the fact that it's scaled to Kerbin's size in the first place?

When you have to carry more fuel mass to get to orbit, craft get bigger, nothing wrong with that. It's interesting that rockets got smaller while spaceplanes got bigger, although it looks like Wanderfound, or hell, even the OP, doesn't have any issues with making small craft.

Except that the Skylon is meant to be smaller than its rocket counterparts carrying the same payload. If you had to build an SSTO that rivals the size of the original multi-staged rocket to carry the payload, it defeats the purpose of the SSTO in the first place. From what Skyon is presenting to us it looks to be at least the size of a medium airliner and not a massive orange fuel tank.

skylon-landed-reaction-engines.jpg

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You just said yourself in a previous post that the lower velocity is to scale with Kerbin's smaller size
The atmospheric heating is supposed to be relatively in scale which is why I was comparing velocities earlier (context there). Atmospheric drag is actually on par with Earth, as I understand it.
Except that the Skylon is meant to be smaller than its rocket counterparts carrying the same payload. If you had to build an SSTO that rivals the size of the original multi-staged rocket to carry the payload, it defeats the purpose of the SSTO in the first place. From what Skyon is presenting to us it looks to be at least the size of a medium airliner and not a massive orange fuel tank.
Skylon is projected to be 83m long and 6.75m in diameter while a Boeing 747-8 is 76m long with an internal cabin width of 6.1m (roughly 9m tall by quick comparison). I don't know about you, but I consider the 747 to be a large plane (one of the top 4, if Wikipedia is anything to go by), not a medium airliner. The big cost savings in Skylon are that it (or was it the engines?) has a projected 200 uses before needing replacement.

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So the new golden standard for SSTOs appears to be a Turbojet-RAPIER mix. The design below isn't particularly good, but it does get a simple ion satellite to orbit on an 'interesting' 35-45 degree ascent throughout.

CTA-10B Valkyrie

Javascript is disabled. View full album

The low drag version (with like, 50% of the wing parts removed) burns up in the atmosphere on a 40 degree ascent (as in, I'm holding +40 degrees from takeoff through the ascent):

m8s5sRN.png

But it did (mostly) make it to orbit:

4qnlBzy.png

Edited by Aanker

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Perhaps I'm missing something here. Now, in fairness, all my tinkering with SSTO planes pre 1.0 was with FAR.

The transition into stock now, is that I have Turbojet engines outputting more thrust than I could previously dream of, requiring fewer intakes than I even needed in FAR, with no need now to stack multiple wing parts in stock to actually get lift, and a supersonic model that makes even my smallest winged FAR craft fly like gliders above mach 2. All in all I can now make faster, more agile craft with fewer parts and more payload than I could before.

So I really don't quite get alot of the arguments in this thread for Single Stage to Laythe craft and that turbojets have somehow been nerfed. It's all a bit confusing.

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The atmospheric heating is supposed to be relatively in scale which is why I was comparing velocities earlier (context there). Atmospheric drag is actually on par with Earth, as I understand it.

Skylon is projected to be 83m long and 6.75m in diameter while a Boeing 747-8 is 76m long with an internal cabin width of 6.1m (roughly 9m tall by quick comparison). I don't know about you, but I consider the 747 to be a large plane (one of the top 4, if Wikipedia is anything to go by), not a medium airliner. The big cost savings in Skylon are that it (or was it the engines?) has a projected 200 uses before needing replacement.

The space shuttle was projected to last 200 uses but only flew 135 missions before they found it to actually be more expensive than launching the payloads using conventional rockets despite the fact that the shuttle is slightly less than half of the original vehicle that returns to the runway. Those projections don't mean much to us until they put it into practice.

If you want to say the Skylon is as large as it is, then you have to admit that the RAPIER counterpart to the SABRE is grossly undersized for the craft it is meant to be attached to when taking those scales into consideration. The RAPIER would need to be at least the size of the mainsail. Unless you have no qualms about creative clipping of several engines into one another for the thing to work, the game's aero and the parts that are provided are grossly mismatched and needs more work.

KSP's aero is the middle child between the soup of 0.9 and NEAR/FAR. It's neither realistic enough and nor flexible enough to allow for engaging gameplay. Now I don't believe KSP is an absolute simulator nor should it be, but with what it currently has, it's not an accurate simulator and it's not a particularly intuitive model. This is coming from a guy who played with deadly re-entry and FAR in 0.9.

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Just in case people genuinely don't get the concept: You have to pay attention to your temperatures during the ascent. When you see a rapid temperature rise, throttle down! When the temperature stops increasing and stabilizes, throttle up! Next, pay attention to orbital speed. When you climb high enough that the rapiers in airbreathing mode aren't accelerating the vehicle anymore, switch modes. I've found it useful to pitch up for a faster climb immediately after switching to closed cycle mode, then pitch down and manage time to apoapsis just like any other launch.

I won't say it's easy exactly... But just some trial and error with the above guide will get you a working SSTO airplane. Yes, it's a fun engineering and piloting challenge. Exactly why I love this game!

Reentry: Get a mod that will display equivalent airspeed. While descending through the upper atmosphere, limit your EAS to 75 m/s. You can use the new airbrakes if you like; I prefer simple pitch control. Experiment with different descent profiles until you find one you like that can hit your desired landing area.

It's fun!

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http://i.imgur.com/7QCfVmV.png

My first poor attempt at an SSTO just jumped right into orbit! :D

Nice... :)

I must say SSTO would be pretty easy if the heat and breaking apart was not in game. But that is the case. I have been messing around with going as fast as possible and as high.. If you basically just ride the red line all the way up.. your getting to space. I can tell by 10000 meters if its going to make it or not.

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Piloting tip stolen from Rune that needs to be shouted across every SSTO thread on this forum (and probably Reddit too):

Follow the mach effects.

- If you have a lot of air disturbance around your plane; pull up until it fades to barely visible.

- If you don't have any of disturbance around your plane; reduce your rate of ascent and gain speed until you have some.

- Repeat until jets fizzle and you go to rockets.

Your jet engines will produce a ton of thrust when you've got a bit of visual effect going on, which spikes your heating, so turn that power upwards and get out of the thick air. Thus far this has led me to 6 perfect ascents in a row with not a single component exploding. I haven't been monitoring temperatures in any way. It's almost as if the devs planned it to work more easily than anyone suspected... :)

As for descent, I just keep the nose at 15 degrees above the horizon and use air brakes. Falling velocity under nuStock is laughably low, and there's apparently no concept of stall, so once you're through the heat zone you can pretty much walk away and make tea while your plane lands itself.

l8vDX2d.jpg

With hands-off, the pilot survived 5/5 landing tests once the plane was in in gentle freefall. The plane doesn't survive unless you flare at the last minute, but that's not too hard. Add any parachute at all and it'll be fine. I just couldn't be bothered using the ones I'd fitted :P

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It felt to me like the OP was lamenting the loss of Turbojet+LV-N to anywhere, which did result in unrealistic outcomes like:

. Yep, those were the days.

I was excited to see that LV-Ns are now liquid only, since I dreamed of pure hydrogen-powered flight when the nuke first game in. On the plus side, that's now possible in stock... but it seems like it won't be winning any performance trophies.

Has anyone manage to get a 'ye olde ram-nuke' to orbit and back? This is the best I've got.

Kerbal-Trine-Trial-11.jpg

I had to red-line those nukes all the way to 70x70 orbit. I had ~100 deltaV for deorbit/landing

With absolutely no features beyond 'carries three kerbals' - it was a very marginal success.

Kerbal-Trine-Trial-20.jpg

Also, the landing needs a little work. Reentry was OK but CoM was just behind/below CoL with dry tanks.

With a little clipping (shoving the nukes forward) it'll land, but what then?

It seems like even turbo/nuke SSTOs can still achieve a thing, but only a small thing.

Clearly SSTOs aren't dead, even the olde kinde, but has anyone eked out some real utility from 'em?

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Seems to me that getting a spaceplane SSTO to orbit now just needs a different flight profile from what we have been previously used to. I've found that staying in the lower atmosphere (10k - 15k) whilst trying to build up speed results in overheating and big explosions. Trying to build up speed much above 18k or so means the engines are running out of oomph and you can actually start slowing down. My successful flights to orbit so far have built up most of the speed on jets between 15k and 18k. I've also found that the Rapier engine, if left in auto switching mode, tends to switch to closed cycle a little early.

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Finally managed to design a spaceplane i like. It's a flying wing design with 4x Rapiers and 1x Aerospike. Has quite a bit of fuel left in LKO but carries a.t.m. only a kerbal. How does one say? In thrust we trust!

Here is it during reentry in a very special way. Airbrakes not needed! :D

jdbcoRS.jpg

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Based on what I've read on this thread, most of the negativity about the new aero/atmo system comes from people who have had existing spaceplanes and spaceplane designs before v1.0 (and using said craft in their own "missions" that they have grown to enjoy) and now are unable to replicate methods they did with older versions of KSP. As you can plainly see from the successful examples given so far, most of these are from people who simply made something new in 1.0, tried it and with a little trial and error, made it to orbit (and even back down again).

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I like how this thread went from "[bLEEP] don't work!" to "Hey, I think we're figuring this out" :cool:

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Clearly SSTOs aren't dead, even the olde kinde, but has anyone eked out some real utility from 'em?
Short answer yes. I think someone made one with 100+ tons payload to LKO. My second attempt at 1.0 spaceplanes can bring at least 36 tons to LKO with 1km/s dv left after separation. It can haul lighter loads to munar orbit and return. If payload was used as propellant it might be in the SSTLaB territory, will have to check on that.

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