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

[qbg]

@qbg: That is correct. The basic jet is set up as a high-bypass turbofan, which spools up to 150 kN static thrust but loses all of its thrust by ~350 m/s. This is representative of the way turbofans behave in the real world, and its role is to get big, heavy planes up to speed to take off. Slapping a bunch on the back of a small plane is pretty pointless; maybe I should make them weigh more to balance their absurd (for a jet) thrust.

Ah, that makes sense. Thanks!

[gilbr0ther]

I am using the latest release of NEAR on ksp 0.25 x64, but the control surfaces do not move, if I regress to version 1.1.1 of NEAR, the control surfaces are once again functional. It's only with me this is happening or is it a bug of the last version?

Sry about my english!

[Las-pen]

Another thing. Let's pretend my wing problem never happened. I had bigger problems with this mod than that. (Let's just say, someone discovered the cheat menu)

Why are the planes so wobbly? Even in low, subsonic speeds and SAS enabled they shake around like a crazy.

I try to pull up, but the plane doesn't pull up straight, but steers to the left or right. (Said plane is symmetric)

Edited October 9, 2014 by Las-pen

[Inglonias]

I have tried this. It's great for planes, but with rockets, it makes things go a bit fast. For instance, my first career mode rocket was three solid rocket boosters stacked on top of each other, and staged via overheating.

I crossed Eve's orbit without even trying.

Is this a bug, oversight, or just weird scaling? If I were to, say, use the RSS mod, would this work a bit better?

[ferram4]

@gilbr0ther: Read the OP, it includes info about your issue, which is not actually an issue.

@Las-pen: That is because SAS is terrible at controlling anything with a high degree of control authority. That is why rocket engines only have 0.5 - 1 degree of thrust vectoring, and why stock control surfaces only work because they're so broken. They hide SAS's brokenness by tuning the parts to the SAS, not the other way around.

FAR has a few control systems that can be activated for most of the things you would want when flying planes, but they were removed from NEAR because people complained about having them.

The pulling to the side is the result of uneven flexing. Happens in stock too. Original solution was to strut everything well, but then Squad made struts not as rigid for some reason and that wasn't an option anymore.

@Inglonias: That sounds like the rocket equation at work, tbh. Work out the dV of your rocket, and then check the dV required to cross EVE.

If you use this with RSS, it'll work, it'll just be kind of weird without the Mach effects.

[iFlyAllTheTime]

I wonder if anyone else is having this issue.

Rather than typing out another long post which caused the original issue, I figured I replicate the issue on a stock-part only rocket as follows:

Mk 16 Parachute

Command Pod Mk1

TR-18A Stack Decoupler

FL-T800 Fuel Tank x 3

LV-T30 Liquid Fuel Engine

To this, I tried attaching Delta Deluxe Winglet in 2 way symmetry and noticed the CoL marker act in a peculiar manner.

When attaching the winglets in any orientation except as described in the next sentence, the CoL behaves exactly as it does without NEAR installed.

When attaching the winglets to the sides of the rocket (If in the VAB, attaching the winglets so that they point directly to the side-walls of the building, where on one side are the elevators perpetually ferrying a vehicle up and down carrying what seems like a fuselage section/fuel tank and the other side has the flag as chosen by the player) the CoL ends up just below the CoM.

This behaviour is noticed when using KW fuel tanks as well as SP+ parts.

Attaching the winglets in a three way (or more) symmetry seems to make the CoM behave like stock.

[ferram4]

CoL is determined based on pitching movement. That behavior seems proper.

[falken]

I have noticed how crazy the rockets accelerate with NEAR, but I know that's because the first 8km or so of atmo on Kerbin is basically custard.

I'm going to give Isp difficulty slider a shot.

Also, enjoying the aircraft behaviours. Just working out how to slow down effectively. Spoilers?

[tetryds]

I have noticed how crazy the rockets accelerate with NEAR, but I know that's because the first 8km or so of atmo on Kerbin is basically custard.

I'm going to give Isp difficulty slider a shot.

Also, enjoying the aircraft behaviours. Just working out how to slow down effectively. Spoilers?

Yes, spoilers and flaps will help.

[AetherGoddess]

I have tried this. It's great for planes, but with rockets, it makes things go a bit fast. For instance, my first career mode rocket was three solid rocket boosters stacked on top of each other, and staged via overheating.

I crossed Eve's orbit without even trying.

Is this a bug, oversight, or just weird scaling? If I were to, say, use the RSS mod, would this work a bit better?

The "Trashcan-o-explosives" SRBs? the ones that are super overpowered and are dropped early in the tech tree in order to make up for the horrible drag system? Ya, been there.

I have noticed how crazy the rockets accelerate with NEAR, but I know that's because the first 8km or so of atmo on Kerbin is basically custard.

I'm going to give Isp difficulty slider a shot.

Also, enjoying the aircraft behaviours. Just working out how to slow down effectively. Spoilers?

or Firespitter/B9 Air breaks.

[iFlyAllTheTime]

CoL is determined based on pitching movement. That behavior seems proper.

Sorry, but I do not understand. Why would placing winglets at the same distance away from the CoM but different orientation change the CoL?

I was trying to be as descriptive as possible in my post since I don't have a way of posting images on the forum. If the problem (if there is one) can be better understood with a pic, I can signup and post the pic.

[ferram4]

Because it's only accounting for the changes in CoP when you pitch the rocket. So any changes in CoP along the yaw axis aren't accounted for. Obviously, I will need to make changes to account for this.

[iFlyAllTheTime]

Because it's only accounting for the changes in CoP when you pitch the rocket. So any changes in CoP along the yaw axis aren't accounted for. Obviously, I will need to make changes to account for this.

I think I understand. Maybe.

I'll just ensure I add at least a three way symmetry when using winglets.

At the expense of sounding too critical, I have something else that's bugging me.

More often than not, when I decouple SRBs they tend to behave unpredictably. They usually fly back into my rocket and takeout my main engine. I've had this with different SRBs, including the smaller sleek looking ones from KW Rocketry. I would expect these small empty boosters to be launched well clear from my main craft, but they seem to bunch up and either hit my rocket or end up hitting each other.

Anyone else with this issue? Any possible fixes one could suggest to me?

Edited October 10, 2014 by iFlyAllTheTime

[NathanKell]

That's a stock bug introduced in .24 to work around a .24x64 bug. It remains in .25.

[AetherGoddess]

I think I understand. Maybe.

I'll just ensure I add at least a three way symmetry when using winglets.

At the expense of sounding too critical, I have something else that's bugging me.

More often than not, when I decouple SRBs they tend to behave unpredictably. They usually fly back into my rocket and takeout my main engine. I've had this with different SRBs, including the smaller sleek looking ones from KW Rocketry. I would expect these small empty boosters to be launched well clear from my main craft, but they seem to bunch up and either hit my rocket or end up hitting each other.

Anyone else with this issue? Any possible fixes one could suggest to me?

Decouplers in .24 started producing their force against the part in an uneven way. this leads to at least a small part of the ejection force being transfered as rotation, meaning the part will flip over and smash into your ship before it's far enough away.

my favorite fix is to use TweakableEverything to adjust the ejection force to 0, which allows the part to gracefully fall straight away, rather then being pushed off and flipping out. this only works if there is a clear route straight from your dropped part against the direction of thrust.

[Boomerang]

Quick question. When playing on stock-scaled Kerbin, are the default DRE settings fairly useful for use with NEAR, or are there any recommended tweaks?

[NathanKell]

Because NEAR doesn't model mach effects, reeentries become harder than they should be. However, they still should be quite survivable, and probably still easier than stock.

[iFlyAllTheTime]

Decouplers in .24 started producing their force against the part in an uneven way. this leads to at least a small part of the ejection force being transfered as rotation, meaning the part will flip over and smash into your ship before it's far enough away.

my favorite fix is to use TweakableEverything to adjust the ejection force to 0, which allows the part to gracefully fall straight away, rather then being pushed off and flipping out. this only works if there is a clear route straight from your dropped part against the direction of thrust.

The TweakableEverything fix worked flawlessly! Thank you.

Although, I love seeing boosters being ejected outward with a bang. Reminds me of the Shuttle SRBs:cool:

Also, I'm guessing the stock game remains unaffected by this rotational force because of the aero model?

[Virtualgenius]

Near does not play nicely with MJ spaceplane guidance keeps ploughing me into the ground I use it to just line up on the runway prior to landing

[ferram4]

NEAR applies forces. It does not provide control systems. Controlled flight into terrain is due to control system or pilot error. Nothing I can do.

[Boomerang]

Another quick question. If there isn't a clear answer I'll start doing some more in-depth trouble shooting. But are there any common problems with having more than one part inside of a cargo bay causing all such parts to not be shielded?

I'm running into this with stock and mod cargo bays both. If one part (stock or mod, doesn't matter) is attached inside the bay, it's labeled as shielded and the bay says that one part is shielded. If I do the same to the other node within a cargo bay, both parts are shielded, etc.

But as soon as I attach another part to a part already within a cargo bay, all of the parts in the bay are unshielded, the bay itself says it's shielding 0 parts. That information is consistent between the editors and on the runway/launch pad. The same problem occurs when adding subassemblies to a cargo bay.

Like I said, if this is a known problem, great, if not, I'm going to be starting a separate game file soon for experimenting with and I'll see if I can replicate the problem in a clean install and if so, what the conflict is.

[Virtualgenius]

Then its a case of MJ cant figure out what forces are being applied and ploughs into the ground

[ferram4]

@Boomerang: Known problem, there's a fix in the current FAR build, but that won't be in NEAR until I finish up what I want for FAR and bring the fixes over.

@Virtualgenius: Or it doesn't do the correct thing with those forces. In any case, nothing I can fix.

[Boomerang]

Thanks for the info and I'll keep an eye out for an update at some point.

[AetherGoddess]

The TweakableEverything fix worked flawlessly! Thank you.

Although, I love seeing boosters being ejected outward with a bang. Reminds me of the Shuttle SRBs:cool:

Also, I'm guessing the stock game remains unaffected by this rotational force because of the aero model?

it is, but the FAR/NEAR drag model correctly models the behavior of the part when it's orientation changes, so the "nose" of the ejected booster suffers pretty sever torque due to wind resistance, where as the stock model causes the ejected part to just rotate at something like 1 deg per second, slow enough for it to drift away before scything your engines. you can see this by taking a similar booster up above the atmosphere and ejecting it. it won't whip around like snake, it'll just drift away, turning gently.