Realism in KSP

[cantab]

Now if there was a way to show people in-game that they were moving about twice as fast as those cars are on the ground for a lower-than-normal-KSP-crazy-speed takeoff, they would understand the forces involved. Saying that it doesn't feel intuitive just means that you don't have a feeling of how fast you're really going in-game, and that's a failure of the game that should really be fixed.

Changeable units on the speedometer, job done.

[ferram4]

Guess what? FAR includes that. No one uses it though, which is kinda sad. If they did they would understand how fast they were going.

[NathanKell]

Didn't FAR nerf the jet engines? This goes against my previous flight sim experience where you are supposed to take off on full throttle. FAR really shouldn't be allowing jet engines to push you beyond 100m/s on ground level.

Can you explain how you plan to have FAR limit what craft a player can construct?

Since unless you want there to be some Magic Force (let's call it, hmm, the Kraken?) that comes out of nowhere to slow down planes on the ground, someone can *always* add MOAR BOOSTERS.

Either your game isn't as 'realistic' as you claim it to be with the ships you use, aerodynamics, physics, time warp, G-forces... or you happen to be better at piloting than a real life astronaut. Take your pick.

I realize we ninja'd each other, but I encourage you to read my above post. On what are you basing those numbers? You....understand that not all LVs are the same, right? Heck, ICBMs (which acheive basically-orbital velocity) typically have main burn times in the 3-4 minute range, with a liquid velocity-adjustment stage at the end. Note that some modern LVs (the Minotaur series) are based on decommissioned ICBMs and thus have similar burn times.

That sounds more like a mod conflict than actual 'realism' where both aerodynamic forces apply. But that's besides the point on whether DRE should be added to KSP without re-balancing it first and all this proves is that it's incompatible with FAR.

Uh, nope. It turns out that capsules have a low ballistic coefficent (high Cd for low mass) for a reason. If you're stock KSP and assume everything has the same ballistic coefficient and the same drag coefficient, then obviously reentries will be harder than if you properly model high-drag capsules.

[NathanKell]

Guess what? FAR includes that. No one uses it though...

Says you, pal.

[Robotengineer]

Guess what? FAR includes that. No one uses it though, which is kinda sad. If they did they would understand how fast they were going.

I use that!

[tater]

If you go back to the first post I've made in this thread, it starts with what do we talk about when we talk about realism. And if you check the posts I've been writing today, they are an answer to the idea that KSP should be accurate enough to pretty much replace text books at universities.

OK, since no one at all is suggesting this, there is no need to ever discuss it. It's not even on the table.

[tater]

If you want a videogame to teach actual aerodynamics, you're probably better off finding old copies of MS Flight Simulator. And books, lots of them.

Every single halfway decent flight sim (combat types---games) "teaches" aerodynamics in an intuitive way without anyone even knowing. People are also pretty much all aware of some basic aerodynamics. Racecars don't look like cabover trucks, for example. No one with 3 neurons to rub together thinks that a pancake would be a good shape for a rocket. I started playing now 3 weeks ago, and from reading the part descriptions IN THE GAME, I assumed I needed to make semi-realistic lego rockets. You know, with nosecones, and all the other stuff you'd expect. Heck, I put a separator on every command pod so it was alone on spashdown. That other things work is counter-intuitive. People actually have to unlearn actual physics, lol. All this for a placeholder, anyway, that the devs presumably want fixed anyway.

This might be relevant. That's the only thing I can reasonably add to this discussion.

Gameplay complexity is good, to a point. That's not the same as interface complexity, however. That is, you can have a game that is not hard to actually play, where the universe and outcomes are in fact quite complex. If that makes sense.

I think most of us in the "more realism" camp like the idea of gameplay complexity, and none of us are actually suggesting a more complex interface between the player and game.

Didn't FAR nerf the jet engines? This goes against my previous flight sim experience where you are supposed to take off on full throttle. FAR really shouldn't be allowing jet engines to push you beyond 100m/s on ground level.

"Full throttle?" Try that in something like an F4U in a game that actually models torque some time. BTW, virtually no one uses full power on takeoff, it reduces engine life. Just like military aircraft don't use afterburners on takeoff. You use as much power as you need. In your other sims, the jets were not designed by YOU, in 5 minutes, using "legos."

Edited September 6, 2014 by tater

[m4v]

Can you explain how you plan to have FAR limit what craft a player can construct?

Since unless you want there to be some Magic Force (let's call it, hmm, the Kraken?) that comes out of nowhere to slow down planes on the ground, someone can *always* add MOAR BOOSTERS.

One or two engines are enough for put a plane into high-pressure-disintegration-before-clearing-the-runway territory though. Honestly I don't know what's up with FAR or the jet engines, when I tried it none of my planes could take off at full throttle without breaking apart, which is the expected thing to do in flight sims.

[ferram4]

Did you rotate and take off below 100 m/s (223 mph, 360 km/h, 194 knots)?

Did you keep your AoA low (< 10 degrees)?

Did you consider the TWR of your plane, and keep it around 1 for a high-performance jet, and 0.3 for a heavier vehicle?

If no, to any of those, you have suffered exactly what would have happened as a result of poor piloting / plane design.

Edit: Compare your designs to the example craft included with FAR. Anything closer to the Hypersonic Demon than any of the others has too much thrust. Proper design of a high-performance fighter looks like the Thunderbird, and for an SSTO, the Velocitas. You need to consider that jets are just as subject to "add engines until TWR -> stupid" as SRBs are.

Edited September 6, 2014 by ferram4

[m4v]

"Full throttle?" Try that in something like an F4U in a game that actually models torque some time. BTW, virtually no one uses full power on takeoff, it reduces engine life. Just like military aircraft don't use afterburners on takeoff. You use as much power as you need. In your other sims, the jets were not designed by YOU, in 5 minutes, using "legos."

From my Jane's F-15 manual. Now I don't fly real planes, but pretty much all the flight sims I played had you taking off at full throttle.

Did you rotate and take off below 100 m/s (223 mph, 360 km/h, 194 knots)?

Did you keep your AoA low (< 10 degrees)?

Did you consider the TWR of your plane, and keep it around 1 for a high-performance jet, and 0.3 for a heavier vehicle?

If no, to any of those, you have suffered exactly what would have happened as a result of poor piloting / plane design.

Edit: Compare your designs to the example craft included with FAR. Anything closer to the Hypersonic Demon than any of the others has too much thrust. Proper design of a high-performance fighter looks like the Thunderbird, and for an SSTO, the Velocitas. You need to consider that jets are just as subject to "add engines until TWR -> stupid" as SRBs are.

I dunno, don't remember now, I don't pay attention to TWR when making planes, but I don't add engines for the sake of adding them and sure as hell I don't look for TWR of 2 like with rockets.

Edited September 6, 2014 by m4v

[juanml82]

OK, since no one at all is suggesting this, there is no need to ever discuss it. It's not even on the table.

Then I think the post about people complaining how it doesn't work in the classroom only show up in my computer.

Every single halfway decent flight sim (combat types---games) "teaches" aerodynamics in an intuitive way without anyone even knowing. People are also pretty much all aware of some basic aerodynamics. Racecars don't look like cabover trucks, for example. No one with 3 neurons to rub together thinks that a pancake would be a good shape for a rocket. I started playing now 3 weeks ago, and from reading the part descriptions IN THE GAME, I assumed I needed to make semi-realistic lego rockets. You know, with nosecones, and all the other stuff you'd expect. Heck, I put a separator on every command pod so it was alone on spashdown. That other things work is counter-intuitive. People actually have to unlearn actual physics, lol. All this for a placeholder, anyway, that the devs presumably want fixed anyway.

What you won't find in a flight sim forum is people complaining because it doesn't really work to teach people how to actually fly aircraft. Yes, they will give you a gasp of aerodynamics and combat maneuvers (for combat sims). But you can be sure that fighter pilots, flying instructors and aeronautic engineers will claim they aren't realistic enough. And they'd be right.

[ferram4]

@m4v: Ah. So basically, you did exceed the TWR and velocities then. Good to know.

Btw, why don't you post the velocity chart that goes with that image? I'm sure it would be quite enlightening about proper takeoff velocities.

[Red Iron Crown]

Then I think the post about people complaining how it doesn't work in the classroom only show up in my computer.

No one is suggesting that it be a college-level, actually-design-aircraft-and-rockets classroom. It's being suggested as a more introductory level simplified experimental sandbox, more targeted at middle and high schools.

What you won't find in a flight sim forum is people complaining because it doesn't really work to teach people how to actually fly aircraft. Yes, they will give you a gasp of aerodynamics and combat maneuvers (for combat sims). But you can be sure that fighter pilots, flying instructors and aeronautic engineers will claim they aren't realistic enough. And they'd be right.

No one is saying it's an appropriate tool for people working professionally in the field, just that it can turn a total layman into an initiate. It is that "grasp of aerodynamics" and other spaceflight concepts that we're after. It doesn't need to be a high-level simulator, but it should strive to be not-blatantly-wrong about the very things it claims to simulate reasonably realistically.

[m4v]

@m4v: Ah. So basically, you did exceed the TWR and velocities then. Good to know.

I suppose, but then is too easy to exceed since I always did without trying to.

Btw, why don't you post the velocity chart that goes with that image? I'm sure it would be quite enlightening about proper takeoff velocities.

Unit is knots I believe.

[ferram4]

Yep, and that looks just about right. Considering the F-15 has two engines capable of 67.9 kN dry, 105.7 kN wet each, and they almost never take off with full AB (why would you? It burns fuel like mad), that should result in (for the heaviest numbers there, 27.2 t mass) that the plane should reach rotation speed (66.8 m/s) in 13.38 s dry, 8.59 s wet after starting its run (having covered 446.9 m and 286.9 m, respectively), before lifting off at 92.3 m/s approximately 18.49 s dry, 11.87 s wet (covering 853.3 m and 547.8 m, respectively). And this is with a plane that has, fully loaded at take off, a TWR of 0.792, and it's taking off this quickly.

If your TWR is higher, this will inevitably be worse. Notice how low the takeoff velocities are, and notice how low the TWR is. Most KSP planes take off at higher speeds with higher TWRs, and this leads to planes being much more failure prone due to piloting and design that provides much less leeway than real-life designs have.

[tater]

Janes, lol. See, you have stuff to unlearn from a game.

What does a real F-15 manual say? Regarding flight sims, people nitpick over very slight elements of aircraft performance. It had to be explained to some that the F4F-3 (not the -4) was actually faster than the A6M at sea level (by ~3 mph), even though it was slower everywhere else. Combat flight sim guys own Shaw (an instruction manual on ACM, written by a real fighter pilot, and used as a text for same) and understand it, too.

Regarding "classroom," it would not even be on the table if it wasn't a demonstrable pitch by Squad (the website has been linked). We're talking for kids, not university. My 8 year old knows that rockets are pointy… maybe because we build and fly actual rockets (as many boys do). Any kid who has built a few Estes rockets would know that tying a few coke cans together with an engine in the middle is a recipe for a tumbling mess. Anyone who knows this sees designs that work in KSP as counterintuitive---because they know that these designs cannot be good (and they are right). You keep having to find something to argue about, I guess. The OP was intentionally painting this as a "total realism" thing (which it is not, and never has been actually about), and in part of attacking that very wrong premise, one rationale was that as an edu tool (stated by Squad), it should at least get the under the hood physics right. Most of us have argued that what's under the hood has exactly nothing to do with how difficult the game is, anyway.

[m4v]

they almost never take off with full AB (why would you? It burns fuel like mad)

I don't know man, is in the manual.

[NathanKell]

Man, I loved those sims. Jane's F/A-18 was my favorite, though...

Yep, sounds like your KSP-plane might well have one or more of these issues:

1. Over-TWR'd without knowing it (easy to do; KSP engines are powerful even after FAR's nerf, and FAR's nerf is only from the last version)

2. Under-lifted: KSP parts are *heavy* (2-5+ as heavy as that size of thing would be in reality) and if you make a plane that *looks* like a fighter, it will likely have the wing loading of the Space Shuttle, not an F-15.

3. Gear too far from CoM: even if the other conditions are fulfilled, you may not be able to rotate because your main gear are too far back, so you'll have to go way faster than you need to in order to take off, just to get enough control authority to pitch up.

[m4v]

Yep, sounds like your KSP-plane might well have one or more of these issues:

1. Over-TWR'd without knowing it (easy to do; KSP engines are powerful even after FAR's nerf, and FAR's nerf is only from the last version)

2. Under-lifted: KSP parts are *heavy* (2-5+ as heavy as that size of thing would be in reality) and if you make a plane that *looks* like a fighter, it will likely have the wing loading of the Space Shuttle, not an F-15.

3. Gear too far from CoM: even if the other conditions are fulfilled, you may not be able to rotate because your main gear are too far back, so you'll have to go way faster than you need to in order to take off, just to get enough control authority to pitch up.

I wasn't trying to get help for making planes in FAR, the point I was trying to make is that what is "intuitive" is subjective. I don't find FAR more intuitive.

[ferram4]

But (I'm guessing) you do find flight simulators intuitive. So what is the difference between flight simulators and KSP + FAR? Besides the lego-plane/rocket design part.

[NathanKell]

m4v: Don't worry, I won't try to inflict help upon you. I was merely conjecturing as to why you were getting what you thought to be unintuitive, unrealistic performance.

[O-Doc]

But (I'm guessing) you do find flight simulators intuitive. So what is the difference between flight simulators and KSP + FAR? Besides the lego-plane/rocket design part.

In X-Plane + Blender, wing aspect ratio, chord shape and fencing actually mean something.

[m4v]

But (I'm guessing) you do find flight simulators intuitive. So what is the difference between flight simulators and KSP + FAR? Besides the lego-plane/rocket design part.

But is the design part what upsets everything, in flight sims you always take off at full throttle and no matter how much you pull the stick, the plane won't break into pieces. Since apparently this is only true for well designed planes then nothing you expect in flight sims will hold true for your average design in KSP. I don't find stock aero intuitive either, but it isn't as punishing. If I disable everything that makes planes in FAR hard, then I suppose I might just keep playing stock and save me the trouble of dealing with the 3.5km/s to LKO and checking what mods are compatible.

edit:

m4v: Don't worry, I won't try to inflict help upon you. I was merely conjecturing as to why you were getting what you thought to be unintuitive, unrealistic performance.

I said unintuitive, not unrealistic, they are not the same thing. I only jumped into the argument because people claimed FAR to be more intuitive than stock, when I don't find either to be intuitive. Edited September 6, 2014 by m4v

[ferram4]

In X-Plane + Blender, wing aspect ratio, chord shape and fencing actually mean something.

Aye, and with FAR, aspect ratio and chord and sweep angle all do matter; they have for a very long time. So your complaint is...?

But is the design part what upsets everything, in flight sims you always take off at full throttle and no matter how much you pull the stick, the plane won't break into pieces. Since apparently this is only true for well designed planes then nothing you expect in flight sims will hold true for your average design in KSP. I don't find stock aero intuitive either, but it isn't as punishing. If I disable everything that makes planes in FAR hard, then I suppose I might just keep playing stock and save me the trouble of dealing with the 3.5km/s to LKO and checking that mods are compatible.

edit:

I said unintuitive, not unrealistic. They are not the same thing, and I only jumped into the argument because people claimed FAR to be more intuitive than stock, when I don't find either to be intuitive.

It's not true for only well designed planes, just ones that aren't over-thrusted, over-weight and under-winged. Incidentally, the way that KSP's stock model teaches people is to build over-thrusted, over-weight and under-winged vehicles (at least compared to proper design), so I don't think that's a problem with realistic physics; I think it's a problem of being taught wrong from the start, and then slowly, over time, planes with TWRs > 1.5 at liftoff and wings the size of a fly are considered normal and intuitive, along with rockets that start with a TWR of 2 and make a 45 degree pitch maneuver at 10 km.

[NathanKell]

m4v: fair enough; apologies for over-snark.

Though I think perhaps the actually-intuitive solution would be non-insanely-OP jets (aka jets that work like jets), and realistic masses, such that the only remaining takeoff issue (gear placement) is shared as a problem between FAR and stock.