[0.90]NEAR: A Simpler Aerodynamics Model v1.3.1 12/16/14

[Alshain]

I'm a little confused by something. After the modifications to the engines, why is the Basic Jet Engine more powerful than the TurboJet Engine?

[ferram4]

@evsey2003: The only "cheat" with FAR is disabling aerodynamically-induced structural failures. Since NEAR has that removed entirely, that "cheat" is always activated, in a sense.

@Alshain: Because the basic jet is a turbofan intended for heavy vehicles at subsonic speeds and the turbojet is an OP engine for pushing you faster than the SR-71 on a lot less fuel.

[Alshain]

@Alshain: Because the basic jet is a turbofan intended for heavy vehicles at subsonic speeds and the turbojet is an OP engine for pushing you faster than the SR-71 on a lot less fuel.

I'm sorry, I still don't understand that. The way it is now, the Basic Jet Engine is more OP than the TurboJet engine.

[Renegrade]

I'm sorry, I still don't understand that. The way it is now, the Basic Jet Engine is more OP than the TurboJet engine.

No, it isn't. The jets have a performance curve that dictates their effective performance far more than the thrust variable. The BasicJet conks out at or before 350m/sec with ZERO thrust. The RAPIER conks out at 1700, and the TurboJet at like 1800.

If you're puttering around at 200m/sec, then yeah, the Basic engine is the one you want. If you want to go to space, you want a TurboJet or RAPIERs. You can still putter around with a TurboJet too.. it's just less efficient in that regime.

350m/sec is sea-level Mach 1-ish. 1800 is 78.4% of orbital speed... Magic rocket jet!

[Alshain]

No, it isn't. The jets have a performance curve that dictates their effective performance far more than the thrust variable. The BasicJet conks out at or before 350m/sec with ZERO thrust. The RAPIER conks out at 1700, and the TurboJet at like 1800.

If you're puttering around at 200m/sec, then yeah, the Basic engine is the one you want. If you want to go to space, you want a TurboJet or RAPIERs. You can still putter around with a TurboJet too.. it's just less efficient in that regime.

350m/sec is sea-level Mach 1-ish. 1800 is 78.4% of orbital speed... Magic rocket jet!

Oh, ok. That makes sense then. I didn't realize there was a velocity that they stopped working, I thought it was just an altitude/intake air then. But I understand now.

[SirJodelstein]

There's something very strange going on with the Large RGU, it seems to have an incredibly high air drag. This is a pure stock + NEAR drop test from 30km, pictures show the stable terminal velocity and attitude at various altitudes. The RGU impact velocity is less than 40m/s.

Thats a .5 ton metal cylinder dropping from the skies. Shouldn't the impact velocity be higher than stock instead of lower? Or maybe this behaviour is actually physically plausible and I need to learn more about aerodynamics?

EDIT: also applies to: small RGU, empty flat rockomax tank (x200-8). Does not apply to a full x200-8 tank.

Edited September 21, 2014 by SirJodelstein

[MaxShadow]

I have a problem with this mod. My framerate drops a lot a few seconds after taking off. It lags for a while and then goes back to normal after leaving the first atmosphere layer. The debug window spams "NEAR Error: Aerodynamic force = NaN" with the name of the wings I'm using (stock). I've heard that FAR had a similar bug but was fixed later. Seems like it's in NEAR too.

[Renegrade]

Oh, ok. That makes sense then. I didn't realize there was a velocity that they stopped working, I thought it was just an altitude/intake air then. But I understand now.

If you take the BasicJet into a dive, it actually generates a small amount of negative thrust > mach1 hehe. It's a good thing though; it means each engine has a purpose. BasicJets are good for hopping around KSC for scooping up science or such, and TurboJets for magically flying into orbit on air power alone

Note that this curve exists in stock as well, although it's actually less pronounced.

Thats a .5 ton metal cylinder dropping from the skies. Shouldn't the impact velocity be higher than stock instead of lower? Or maybe this behaviour is actually physically plausible and I need to learn more about aerodynamics?

Well that's the thing, it's only 0.5t in mass, and has a cross-sectional surface area of almost 20 square meters. I'm a bit surprised it falls flat like that but given that it does, the speed makes sense. It's like a steel parachute going 144km/h (90mph).

The difference between the full and empty tanks are the same: the empty tank has the same large cross section as the full one (and thereby drag), but is like 4 tons less mass. I believe the tank has the same dry mass as the large RGU core in fact..

[Cairan]

I've tried out both NEAR and FAR with the latest B9 release yesterday... Great mods! However...

...since the idea of NEAR is to transition people into the realm of more realistic aerodynamics, yet not be full-blown into the CFDverse kingdom, and that many people already have existing launch vehicules in advanced save games (ie. I have an Interstellar + Kolonization save game, quite advanced into the colonization of Kerbol...), I've removed NEAR for the time being as it breaks too many designs. I know this is exactly what is supposed to happen, but please keep on reading!

What if you could activate the NEAR code on a per-spacecraft basis?

My idea would be to have a GUI right-click option available in command pods and cockpits. By default, the NEAR code would apply to the current vessel, however, as a tweakable toggle option, the command pod controlling the spacecraft could deactivate it and revert to stock's infamous mass <--> drag relationship. That way, the player can learn how to build proper spaceplanes and rockets, yet continue to use MechJeb for landing guidance of returning probes and capsules or for launch ascent guidance of existing designs. A configuration option could be in the NEAR configuration files to drive the default behavior, either to apply stock (equivalent to deleting NEAR), all vessels or per vessel.

Otherwise, I have to say I am very impressed with both NEAR and FAR, great job to all those who have worked on these mods!

[ferram4]

No. Inconsistency in physics is the one thing that annoys me more than anything else, and I'm not going to encourage it.

[Cairan]

No. Inconsistency in physics is the one thing that annoys me more than anything else, and I'm not going to encourage it.

Coming over from 10+ years of playing Orbiter, I know exactly what you mean. Yet, I thought, and still think, this might be a good option to put the "frog in cold water and turning up the heat" ... After all, in MSFS and XPlane, you can tweak the aerodynamic models and physics, hence my suggestion.

Thanks again for the good work, and when 0.25 rolls out, FAR or NEAR, is going to be the first mod installed before the first launch of anything

[ferram4]

Alright, so update to v1.2. Has a few bugfixes and 0.25 compatibility.

Also, NEAR will shut itself down if you are using the win64 build of KSP. This is due to that build's instability, which has only worsened with the 0.25 update.

[Maikie_G]

Also, NEAR will shut itself down if you are using the win64 build of KSP. This is due to that build's instability, which has only worsened with the 0.25 update.

That's very unfortunate. I rather liked playing with NEAR and the win32 build was too restricting for me memorywise.

[Cuky]

I am getting a message that NEAR is not compatible with 0.25.0 when game starts loading.

[biohazard15]

I am getting a message that NEAR is not compatible with 0.25.0 when game starts loading.

Same thing here.

[ferram4]

Noted and fixed with a reupload.

[Alshain]

Anyone else having trouble getting lift?

[ferram4]

That's supposed to happen. The CoL / CoP / aerodynamic center is a point, not a vector. The vector is damn useless, and was confusing. So I removed it.

[Alshain]

That's supposed to happen. The CoL / CoP / aerodynamic center is a point, not a vector. The vector is damn useless, and was confusing. So I removed it.

Oh, well, except I can't get it in air. This is a converted plane that flew fine before. Actually it almost seems like I'm not getting up to speed, maybe not the lift but something wrong with the turbo jet.

EDIT: Actually, I changed the intakes. let me go back to the original craft and try again.

EDIT2: Nope, I can't get it past 100m/s before the end of the runway.

Edited October 7, 2014 by Alshain

[NathanKell]

Intake drag is now accounted for. That could be why.

[Alshain]

Intake drag is now accounted for. That could be why.

I stripped it down from an SSTO to a jet removed all the oxidizer and got it off the ground but still won't go above 120m/s with a single set of the new intakes. A plane this this tiny should be lightning with a turbojet.

[ferram4]

You're not using win64, right? NEAR shuts itself down on win64, as noted in the OP.

[Alshain]

You're not using win64, right? NEAR shuts itself down on win64, as noted in the OP.

Nope, plus I have flaps/spoilers and such on the menus. Maybe the craft file didn't convert right, I'm gonna try just rebuilding from scratch. Not that complicated a plane anyway.

EDIT: Nope, complete rebuild (of the jet, not SSTO) and I'm still barely able to get off the ground, if at all.

EDIT2: I'm not sure this is a NEAR issue. I uninstalled it and although the engine was more powerful, it was still weaker than I expected it to be for stock. It's almost like it's been nerfed, but to an unusable level. I'm gonna try re downloading the whole game and after that I'll discuss it in the support forum.

Edited October 7, 2014 by Alshain

[ferram4]

Issue confirmed, fixed, and a new version has been uploaded to fix the gamebreaking issue.

[Alshain]

Issue confirmed, fixed, and a new version has been uploaded to fix the gamebreaking issue.

Oh thank you so much, I was beginning to think I was going insane.

EDIT: Much better, got all the way to space.

Edited October 8, 2014 by Alshain