Squad is slowly reintroducing soup o' sphere with 1.01

[mcdjfp]

I have two things to add. First, I am extremely happy with 1.0 and most of what is in the 1.01 and 1.02 patches. On the other hand there is something "wrong" with the atmospheric changes in the 1.01 patch. I wish I had the exact numbers to pin it down, but while 1.0 felt semi-realistic (there were problems), 1.01 just feels off. Soupier seems to be close to the right description.

1.0

I immediately tested several of the stock craft as I normally do when a new patch comes out. In this case I tried the launch tutorial and then tried to land the craft. I was quite pleased with the results of the flight as vulnerable components of the craft (exposed batteries for instance) burned off until about peak heating where the unprotected, and fairly full, fuel tank exploded. The capsule and parachute were survived until a reasonable altitude for the parachute to be deployed. The Learstar surprisingly launched (instead of tumbling out of control) and on reentry with the nose well up slowed enough (almost too much as there were no reentry effects at all) in the upper atmosphere. I then threw the Ion probe up on a booster which I then deorbited (the booster). It almost exploded, but as it was just an engine, fins, and empty tanks (light for its size) it survived to crash into the ground. So long as I left exploits and other game engine abusing behavior alone, it felt like a great starting point.

1.01

Too much too soon. These changes never should have happened in this patch even if they are the right ones in the end. According to the patch notes there were many other fixes and adjustments. The effects of those changes should have been given some time first before other changes were made. Making the changes all at once makes it hard to know exactly how much of a change was needed. I have had troubles with space planes. Not only have I experienced the full power dive deceleration, but I have leveled out of a climb, and found no speed increase. Yes, there is terminal velocity, but when I level out, the trust that was fighting gravity pushing up is now pushing the plane forward and should result in a noticeable speed increase. Heavy craft now decelerate so quickly that exposed hardware (the tiny surface mounted solar panels, RCS tanks, batteries) easily survive even fairly steep reentries. Heat shields serve little purpose (at least before interplanetary stupid fast aerobraking), and I only wish I could see the new heat overlays that were added without having to try so hard.

1.0 needed some work, but 1.01 feels worse, maybe the sweet spot is in the middle, or maybe the numbers were right and the model needs a few tweaks, but until then, go back to a mostly 1.0 physics config

[JWag]

Anyway, real life rockets never deviate far from the prograde vector during atmospheric flight, because they do not have the structural integrity to survive the aerodynamic stresses this create.

Another excellent point, and another advantage we have in KSP.

In KSP I've recovered some missions where I got aggressive and flipped, especially if I keep it to a 360 degree flip and don't lose too much velocity. A real rocket would be thousands of rocket fragments in a fireball. Even when KSP is hard, it's much more forgiving than the real thing.

[maccollo]

I was wondering how much impact that would make, using separate fuel and oxidizer tanks. Would the fuel:oxidizer mass ratio also affect it? KSP uses a nearly 1:1 fuel-ox mass ratio, whereas I believe in real rockets the oxidizer is a few times more massive than the fuel.

Liquid hydrogen only has a density of 0.07 tonnes per cubic meter, while liquid oxygen has a density something like 1.14 tonnes per cubic meter, 16 times more dense than liquid hydrogen.

I believe kerosene has a density of about 0.8 tonnes or so, so even there the oxygen is quite a bit denser.

Also, the gravity turn at a high altitude was brought back, and I was enjoying starting the turn just after launch.

Can someone tell me where to start the turn now? I'm soooo confused.

Impossible to tell precisely without knowing the rocket. What's the TWR of stage 1? What's the delta V? What's the TWR at stage burn out? What's the TWR of the second stage?

Generally though, it ranges from right away for high TWR rockets, to after after you reach 100 m/s for lower TWR systems.

Here's an example of an asparagus staged rocket with a rather high TWR of 1.76.

[Superfluous J]

1.01/1.02 drag is more unforgiving if you want to perform an efficient gravity turn. While it only takes a couple 100 m/s more to get to space (3200 is my lowest so far), you have to be much more accurate so that the trajectory begins to flatten out just as the atmospheric density begins to drop really fast. If you pitch is a bit to weak you end up flattening out much higher than nessesary and you loose a lot more to gravity losses. Pitch a bit to hard and the trajectory will flatten while you are still flying through the dense atmosphere, and even if you can save it you are punished severely for it in atmospheric drag losses.

I'd be interested in knowing more. Obviously what worked in FAR and 1.0 don't work now. How much higher do I need to go? What are some rough benchmarks for degree tilt vs altitude, speed, apoapsis, or whatever else makes for a good metric?

[SelectHalfling0]

Impossible to tell precisely without knowing the rocket. What's the TWR of stage 1? What's the delta V? What's the TWR at stage burn out? What's the TWR of the second stage?

Generally though, it ranges from right away for high TWR rockets, to after after you reach 100 m/s for lower TWR systems.

Here's an example of an asparagus staged rocket with a rather high TWR of 1.76.

Thanks for the video. What was that rocket payload though? I just launched an early career rocket in 1.0.2 with the old launch method (.90) and it worked, to my dismay, beautifully.

Edited May 2, 2015 by SelectHalfling0

[Geschosskopf]

In KSP your tank just drains top to bottom as if the fuel and oxidizer were pre-mixed.

Yeah, this is has always been a major problem of implementing "realistic"* aerodynamics in KSP. Its whole engine/fuel system, pretty much the single most-important game mechanic, is fundamentally unsuited to "realistic" atmosphere stuff. All the "realsim"-mongers in KSP over time have utterly failed to grasp the point that you can't just impose "realism" on 1 or a few aspects of the game in isolation without hosing up the whole shebang. "Realism" has to be a matched set from end to end of the game system, meaning it's a slippery slope. Once you uncork "realstic" aerodynamics, you pretty much need to scrap the existing fuel system and separate LF from O in separate, ideally also stretchy, tanks. Once you introduce heat, you now have to have radiators. And so on.

I'm rather saddened to see KSP morphing away from a fun form of entertainment and into a simulation. I played Orbiter for many years before KSP came along. Orbiter tries hard to be as accurate to real life in all respects as possible, which isn't very fun. That's why I kicked it to the curb when KSP came along. I really, really wish those who demand "realism" in KSP would just go play Orbiter and leave KSP alone.

*What IS truly realsitic in KSP? The laws of physics are fundamentally different there, as shown by Kerbin having Earth's gravity despite being way, way smaller. The entire KSP solar system is made of exotic matter, not what we have, so Kerbin's atmosphere should NOT behave just like Earth's, or even contain oxygen as we know it. So suffice to say that applying Earth-like atmospheric effects to Kerbin is certainly wrong and internally inconsistent with the rest of the solar system, and the old "soup-o-shere" is probably closer to realism in the KSP universe. The only way to have Earth-like air be realsitc in KSP is to go all RSS so matter is the same there and here. But that's a subject for another thread.

[maccollo]

I'd be interested in knowing more. Obviously what worked in FAR and 1.0 don't work now. How much higher do I need to go? What are some rough benchmarks for degree tilt vs altitude, speed, apoapsis, or whatever else makes for a good metric?

I think reaching 45 degrees just as you cross 10 km might be a pretty good one, but I havn't played around enough to get a really good feel for it. I'll be experimenting some more lower TWR rockets.

One thing I should add is that since this rocket is rather fat it's more forgiving if you need to adjust the trajectory, because the cross sectional area doesn't change as much when you point it off prograde as it would with a longer and skinny rocket.

Thanks for the video. What was that rocket payload though? I just launched an early career rocket in 1.0.2 with the old launch system (.90) and it worked, to my dismay, beautifully.

276 tonnes, with an initial mass of 1084 tonnes, so a payload fraction of about 25%. The deltaV to orbit was about 3150 m/s for this attempt, very much closer to the 3 km/s in 1.0 than the 4.5 km/s with the old soup.

One thing I should add is that this is a big and fat rocket, so it should be more forgiving than a long and thin rocket. A thin rocket will increase it's surface area much more with the same angle of attack.

[Ledenko]

I did a simple test, I'm not much of a pilot but but this was simple enough to do. Basic rocket, first stage 2x FL-T800 on an LV-T30, second one FL-T800 also on an LV-T30. Mk1 pod and some canards and away we go! (Slowly though, TWR at takeoff is 1.27)

First launch: straight up to 10km, turn to 45° and reach an apo of 80km. The whole turning at 10km happened, but sloooowly, the craft did NOT want to turn. Final result, 3684dv spent getting to 80x80km orbit.

Second launch: Go at full throttle, at 100m/s begin gravity turn. Went uneventfully to 80km apo and circularized. Used up 3439dV.

Final tally: 245m/s dV saved.

Here's the thing though - with a different configuration, I'd probably get completely different results. TWR, shape, ISP, thrust etc all influence what the best ascent profile will be for a craft.

[panzer1b]

Yeah, this is has always been a major problem of implementing "realistic"* aerodynamics in KSP. Its whole engine/fuel system, pretty much the single most-important game mechanic, is fundamentally unsuited to "realistic" atmosphere stuff. All the "realsim"-mongers in KSP over time have utterly failed to grasp the point that you can't just impose "realism" on 1 or a few aspects of the game in isolation without hosing up the whole shebang. "Realism" has to be a matched set from end to end of the game system, meaning it's a slippery slope. Once you uncork "realstic" aerodynamics, you pretty much need to scrap the existing fuel system and separate LF from O in separate, ideally also stretchy, tanks. Once you introduce heat, you now have to have radiators. And so on.

I'm rather saddened to see KSP morphing away from a fun form of entertainment and into a simulation. I played Orbiter for many years before KSP came along. Orbiter tries hard to be as accurate to real life in all respects as possible, which isn't very fun. That's why I kicked it to the curb when KSP came along. I really, really wish those who demand "realism" in KSP would just go play Orbiter and leave KSP alone.

*What IS truly realsitic in KSP? The laws of physics are fundamentally different there, as shown by Kerbin having Earth's gravity despite being way, way smaller. The entire KSP solar system is made of exotic matter, not what we have, so Kerbin's atmosphere should NOT behave just like Earth's, or even contain oxygen as we know it. So suffice to say that applying Earth-like atmospheric effects to Kerbin is certainly wrong and internally inconsistent with the rest of the solar system, and the old "soup-o-shere" is probably closer to realism in the KSP universe. The only way to have Earth-like air be realsitc in KSP is to go all RSS so matter is the same there and here. But that's a subject for another thread.

I completely agree, realism for teh sake of realism isnt exactly a good move in a game thats all about fun (or at least thats what i liked about KSP, i have plenty of flight sims around when i want realistic flight).

Also, about kerbin having earth gravity, i explain that by assuming kerbin's core is made of some far denser material, its not ENTIRELY out of the possibility. This is how i explain that certain planets which appear the same size can have different gravity, as one planet has a denser core then another. Its not like this cant happen in reality, although i do believe that most planets are formed out of similr composition (im no astrologist, i got no idea about space and all that, just play game for fun).

[Eliijahh]

Can't you just modify the Physics file back, and have the old 1.0 aerodynamic?

[Renegrade]

*What IS truly realsitic in KSP? The laws of physics are fundamentally different there, as shown by Kerbin having Earth's gravity despite being way, way smaller. The entire KSP solar system is made of exotic matter, not what we have, so Kerbin's atmosphere should NOT behave just like Earth's, or even contain oxygen as we know it. So suffice to say that applying Earth-like atmospheric effects to Kerbin is certainly wrong and internally inconsistent with the rest of the solar system, and the old "soup-o-shere" is probably closer to realism in the KSP universe. The only way to have Earth-like air be realsitc in KSP is to go all RSS so matter is the same there and here. But that's a subject for another thread.

The surface gravity is correct for Kerbin's mass. The gravitational constant is correct. There's nothing wrong with it. Sure, the average densities are high, but extreme densities are not unknown to science (a pickup truck's bed 1/3 full of neutron star matter would weigh as much as Gilly, and have a surface gravity in the tens of thousands of g₀ or more).

If you placed masses with the same size and mass as Kerbol's planets in similar orbits, they'd have similar orbital mechanics (within the limits of patched conics).

Anyhow, if these changes are some sort of.. ill-advised Squad-ian attempts to restore the same delta-v numbers as the old soup-o-sphere, they need to drop it. It's not like KSP was ever that finely balanced to begin with.

[georgTF]

Can't you just modify the Physics file back, and have the old 1.0 aerodynamic?

Yeah but then you have 1.x parts flying in 1.0 aero or other issues.

[Shadowlord]

So I figured out why my rockets were terrible in 1.0.2. Turns out that it was the rockomax fuel tanks, apparently. When I built a rocket with FLT tanks, it easily sailed through the atmosphere, but one with equal mass built with a rockomax tank couldn't make it at all. (Radial parachutes also appeared to contribute a little.)

I don't know if the adapter parts would alleviate this - I haven't researched them, since in 1.0 they weren't needed (and switching from the FLT tanks to rockomax tanks in 1.0 resulted in a huge boost in the effectiveness of my rockets).

[cantab]

Yeah, this is has always been a major problem of implementing "realistic"* aerodynamics in KSP. Its whole engine/fuel system, pretty much the single most-important game mechanic, is fundamentally unsuited to "realistic" atmosphere stuff.

Rockets fly well enough in FAR, which targets realism without much regard for gameplay impact. The way the fuel tanks are done can be a nuisance but it's not a showstopper issue.

Realistic physics is what has made KSP the game it is. In a world full of space games with sci-fi trope flight mechanics Squad were bold enough to make a game where spacecraft fly as much like the real things as practical. I feel that philosophy should be stuck with.

As for the size of the celestials, I don't consider an unrealistic solar system in opposition to having realistic physics in that solar system.

[maccollo]

Modified my launcher to have two stages and a low TWR (1.2) at lift off. Now I wait until I reach 60-80 m/s before initializing the gravity turn, and the 45 degree mark happens just before 20 km. It's actually still slightly efficient (30 m/s or so) to still have reached 45 degrees at 10 km, but then the second stage has to power through the 20-30 km altitude at a rather awkward angle of attack and it seems like it would be pretty easy to undershoot.

[SelectHalfling0]

Modified my launcher to have two stages and a low TWR (1.2) at lift off. Now I wait until I reach 60-80 m/s before initializing the gravity turn, and the 45 degree mark happens just before 20 km. It's actually still slightly efficient (30 m/s or so) to still have reached 45 degrees at 10 km, but then the second stage has to power through the 20-30 km altitude at a rather awkward angle of attack and it seems like it would be pretty easy to undershoot.

This helps quite a bit!

[Mister Spock]

I haven't played enough to have a strong opinion, but my initial impression is that 1.0.2 is a far cry from the old soup-o-sphere. It seems to me more like FAR. Maybe a bit higher drag lower down, a bit less higher up?

As for conventional jet performance, 1.0.2 seems okay to me. Tooling around with the stock jets at low altitude, they behave reasonably. Maybe a tad easier to land than they might be in real life, but nothing that bothers me. Certainly not the slow-motion descents I used to get in the old stock.

[Shadowlord]

Apparently, according to KER, the TWR on my extremely-efficient-in-1.0 rocket's second stage is 0.66, and while switching to TWR tanks solves the drag problem for the most part, it doesn't fix the TWR (which causes the speed to drop and progress to slow until it burns half its fuel).

Although I didn't have KER installed before now, I know it must've had a high TWR in 1.0, since it shot through the atmosphere like a bullet on speed and easily made it to 100km without slowing down, while flying straight up...

... Wait... Could it be the service bay? I have a materials bay (Science Jr) "inside" it, with other science instruments stapled to the materials bay, and the bottom of the rocket attached to the materials bay. (Because I tried to attach the science instruments to the inside of the service bay and was unable to do so properly so it didn't look like ...., and eventually gave up and just jammed the materials bay there instead on the assumption that it would magically remove the drag on & protect from re-entry the things stapled to it. The fact that I was attaching all the fuel tanks and engines to the materials bay didn't even occur to me. Hmm.)

[Enceos]

I can confirm, the stock 1.0.2 drag profiles are so high that even in a 30° dive you still lose speed without any aero brakes.

[Superfluous J]

I can confirm, the stock 1.0.2 drag profiles are so high that even in a 30° dive you still lose speed without any aero brakes.

How fast are you going and how low in the atmosphere are you? If you're going 100m/s 45km up there's a problem. If you're 1km up going 2000m/s then I'd expect anything to slow down. Somewhere in the middle you'd not be able to accelerate, but wouldn't decelerate.

The simple fact that it happens means nothing.

[Decoherent]

Heat shields serve little purpose

I was wondering about that. Last night I was landing a Minmus mission, two Mk1 pods + Science Jr + Service Bay with some stuff, and as I reached the atmosphere, realized I'd put the heat shield on the wrong side of the stack decoupler. I decided I'd ride it down anyway for the lulz, and was floored to end up landing safely. I don't think service bays are supposed to serve as heat shields, much less cheerfully survive. Launching my rockets seems a lot harder as well. Launching that Minmus mission was the identical craft I'd run for an identical mission a couple hours earlier in 1.0, and I ended up needing to strap boosters to it and still ended up with almost 500m/s dV less in orbit.

[Bill Phil]

I was wondering about that. Last night I was landing a Minmus mission, two Mk1 pods + Science Jr + Service Bay with some stuff, and as I reached the atmosphere, realized I'd put the heat shield on the wrong side of the stack decoupler. I decided I'd ride it down anyway for the lulz, and was floored to end up landing safely. I don't think service bays are supposed to serve as heat shields, much less cheerfully survive. Launching my rockets seems a lot harder as well. Launching that Minmus mission was the identical craft I'd run for an identical mission a couple hours earlier in 1.0, and I ended up needing to strap boosters to it and still ended up with almost 500m/s dV less in orbit.

Service bays have heatshields.

The he new aero barely affects my 1.0 rockets. I'm a ok.

[TheBrisbyMouse]

It seems you all are kicking the dog for something the cat did.

I don't think the problem is the across-the-board increase in drag, it's the transonic drag sticking around after you pass Mach 1.

I did testing on this using a testbed consisting of an LV-T45, a 1m cockpit, and 8 tier 0 winglets. Flight profile was a full throttle burn level @ 300m altitude. When I hit Mach .8, acceleration dropped sharply from ~6 gees to 2, and it stayed that way until I crashed into the ocean at Mach 2.

AFIK IRL once you pass ~Mach 1.2, transonic drag disappears.

[kmMango]

Jeez. Everyone moaned about 1.0's model being unrealistic, so they fixed it. Now you want it back?

Be glad that Squad is so attentive to their community that they are willing to change the flipping laws of physics every week to make us happy!

Just sit sit down and try it. People already have Mk 3 SSTOs. Even a lot of old SSTO's from 1.0 work, they just need to be flown differently.

This guy

http://forum.kerbalspaceprogram.com/threads/117535?p=1891321&viewfull=1#post1891321

This guy

http://forum.kerbalspaceprogram.com/threads/118470-1-0-2-Any-hope-left-for-SSTOs?p=1891988#post1891988

And even THIS guy

http://forum.kerbalspaceprogram.com/threads/117164-Arkingthaad-in-1-0?p=1872848#post1872848

Have all done it.

Now quit whinin' and start flyin'!

Edited May 2, 2015 by kmMango
I don't like complainers.

[georgTF]

Jeez. Everyone moaned about 1.0's model being unrealistic, so they fixed it. Now you want it back?

Not everyone moaned. And nobody expected the soup to return. Also, seems roughly half the players are happy with 1.0.2 aero, with the other half split between complaining that it's less fun or too draggy for their taste.