[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[Crzyrndm]

Easy?

I thought one of the things this mod does is making lift a function of the squared airspeed like it is.

Is not that supposed to give us the realistic V speeds?

A) That assumes everything else also lines up to RW specs (wing area, mass, etc.). Kerbal designs often lack in wing area AND have rather high mass for their size

FAR doesn't simulate ground effect which I'm about 90% certain would help reduce required takeoff velocity

[SkyRender]

I've noticed a rather strange tendency of craft to oscillate when returning from orbit, often around an aerodynamically stable point. Basically, the craft will rock back and forth rather dramatically over the retrograde marker. By around 0.8atm the oscillations are almost manageable, and by 0.9atm they can be brought under control. Is that a behavior that actually happens in real life? I'm genuinely curious.

[Wanderfound]

Overlapping stock jets, it looks like.

Yup. Eight Turbojets, two RAPIERs, one Mainsail. The Mk3 stuff could definitely make use of 2.5m jets if they were available.

[NathanKell]

DaMichel, does AJE have my tweakable-drag patch? It's on my repo, dunno if camlost is using it. Basically, it sets inlet drag based on AJE inlet are * a tweakable factor, so you can try to figure out what should be correct.

[Genius Evil]

Has the FARBasicDragModule changed with FAR for 0.90? Several parts I made which used it worked fine on my 0.25 install; but on 0.90 the FARBasicDragModules seem to have no effect. I created this cfg to see if something else was causing the issue:

PART
{
name = DRAGTEST
module = Part
author = BLA


  //BLADES///////////////////////////////////////////////////////////////////////

    MODEL {
    model=AJE/VTProp/Blades/HSCOBlade1
    position = 0.0, 0.1375, 0.0
    scale = 1.69,1.69,1.69
    rotation = 0, 0, 0
  }
    MODEL {
    model=AJE/VTProp/Blades/HSCOBlade2
    position = 0.0, 0.1375, 0.0
    scale = 1.69,1.69,1.69
    rotation = 0, 120, 0
  }
    MODEL {
    model=AJE/VTProp/Blades/HSCOBlade3
    position = 0.0, 0.1375, 0.0
    scale = 1.69,1.69,1.69
    rotation = 0, 240, 0
  }
    MODEL {
    model=AJE/VTProp/Bits/Spinner
    position = 0.0, 0.1375, 0.0
    scale = 2.083,2.083,2.083
    rotation = 0, 0, 0
  }

	//PROPERTIES///////////////////////////////////////////////////////////////////////

	rescaleFactor = 1

	node_stack_top = 0, 0, 0, 0, 1, 0, 1

	///////////////////////////////////////////////////////////////////////////////////

	TechRequired = aerodynamicSystems
	entryCost = 2800
	cost = 950
	category = Propulsion
	subcategory = 0
	title = TEST
	manufacturer = BLA
	description = BLA

	///////////////////////////////////////////////////////////////////////////////////

	attachRules = 1,0,1,0,0

	mass = 0.1
	dragModelType = default
	maximum_drag = 0
	minimum_drag = 0
	angularDrag = 0
	crashTolerance = 7
	maxTemp = 300
	fuelCrossFeed = True
	CoMOffset = 0, -1.2, 0

	MODULE
	{
		name = FARBasicDragModel
		S = 5.0

		CdCurve
		{
			key = -1 0.004 0 0 // stern on
			key = 0 0.001 0 0 // sideways
			key = 1 0.003 0 0 // head on
		}
		ClPotentialCurve
		{
			key = -1 0 0 0
			key = -0.5 -0.001 0 0
			key = 0 0 0 0
			key = 0.5 0.001 0 0
			key = 1 0 0 0
		}
		CmCurve
		{
			key = -1 0.001 0 0
			key = -0.5 0.0 0 0
			key = 0 -0.001 0 0
			key = 0.5 -0.002 0 0
			key = 1 -0.004 0 0
		}
		ClViscousCurve
		{
			key = -1  0.0 0.0 0.0
			key = 0.0 0.0 0.0 0.0
			key = 1.0 0.0 0.0 0.0
		}
	}


}

In 0.25, this has the proper Cd of ~0.05, but in 0.90 it has a Cd of over 2. Changing the values in the cfg seems to have no effect in game. Is this just a problem with my install?

[Guest]

https://www.youtube.com/watch?v=Q0WtuvOpr_o

How hard is 27.6 G in FAR? I'm really proud of it xD

I recently reached it with a joypad and a new plane using a "smart frame": F-51 Yorzin

What do you guys think of the graph and frame?

Nice update ferram4 btw

Edited January 26, 2015 by RevanCorana

[smjjames]

I've noticed a rather strange tendency of craft to oscillate when returning from orbit, often around an aerodynamically stable point. Basically, the craft will rock back and forth rather dramatically over the retrograde marker. By around 0.8atm the oscillations are almost manageable, and by 0.9atm they can be brought under control. Is that a behavior that actually happens in real life? I'm genuinely curious.

I've seen similar behavior with rockets, except in the opposite direction. I have no idea how normal that behavior would happen in real life. Minor oscillations are probably fine, maybe even expected, but big ones (big enough to say 'dramatic') would definetly be a no-no because of torsion stress, among other potential problems.

[UristMcKerbin]

There is code in .part for B9 intakes to make them better at higher altitudes and speed (which doesn't make any difference anyway), but it is disabled for FAR/NEAR, so one can expect that FAR simulates better math for them, though there is still no difference, leaving B9 intakes and stock structural intake complete garbage. Is it supposed to be so?

[ferram4]

@DaMichel: Yes, I know. Intakes play very, very badly with attempts at dealing with clipping. Yes, I am aware. No, I don't know how to fix it right now. Yes, it would be fixed if part clipping weren't possible. I don't know what to do, besides try and refactor everything, which I'm doing, but it will be slow.

Sometimes I think part clipping got enabled just to mess with FAR; it's a complete disaster.

@SkyRender: I'm not seeing the problem. It oscillates around a stable point, with the oscillations slowly dying down over time... that's what happens. That's how any stable system behaves.

Really, it depends on what vehicle you're talking about, as is always the case with these questions. Rocket? Probably realistic, but will end badly. Capsule? Realistic, nothing to worry about. Spaceplane? Probably also realistic, likely to break up. Things are complicated, one-size-fits-all answers don't really work well here.

[DaMichel]

Hold on a moment! No need to be upset, sorry if i offended you.

But i still don't understand. How are intakes different from other parts with respect to clipping? All i see are roughly similarly shaped parts with huge differences in drag force. And no clipping going on. I have no idea how it all works internally.

Edit: Well, the wing parts where the nacelles are mounted clip into the nacelles.

I think last time you said that Cd depends on the inlet area. Is this the "Area" you see in the RMB menu (with AJE)? Even knowing that i still don't get it.

It seems more like simple issue of tweaking some numbers than a algorithmic problem.

I'd also think that the drag of intakes is lower than drag of comparable non-intake parts because air flows through the intake and therefore there is less pressure in front of the intake needed to deflect air. That is just my intuitive understanding. Might be all wrong.

@Nathan: what code are you talking about? I did a brief search but found nothing.

Edited January 27, 2015 by DaMichel

[blowfish]

As far as I can tell AJE and FAR don't interact at all as far as inlet drag is concerned. AJE does a ram drag calculation but that is subtracted from thrust rather than affecting the inlet in any way.

[HoneyFox]

I get this curve graph from x-plane's website and it seems like it's a pretty generic one for Cl(green)/Cd(red)/Cm(yellow) with alpha ranging from -180 deg to +180 deg, because we can see the stall angle judging from the Cl curve's peak point. the drag curve looking normal, and Cm curve as well having a sudden change at the stalling alpha.

I will post some curve graph in FAR to make some comparison later.

EDIT: Here is a sample curve in FAR.

There're some differences in Cl & Cd curves, but at least the shapes are still roughly the same.

But for Cm curves, I just don't get it. I talked to you on irc earlier about this, and here's it is.

Looks like the Cm curve in FAR has followed a complete period of a sine-ish wave from alpha 0 ~ 180 deg, while the Cm curve in the above graph only passes half period in the same alpha range.

Edited January 27, 2015 by HoneyFox

[mecki]

I don't know if this is issue belongs to FAR, Procedural Fairings or DeadlyReentry so please tell me if I should ask it in another thread.

When I load a previously saved ship and start it, my procedural fairings have two info fields for "Temperature" and "Ambient" on right-click.

I also have the feeling that those fairings heat up faster.

[DaMichel]

HoneyFox (and Silverfox, too) you just gave me an awesome idea. Actual "wind tunnel" testing!

The strange Cm curve is not just a glitch in the graph. You can tell by the pitch control display that the 45 deg orientation is harder to hold than 90 deg.

I made sure that the axis of rotation goes through the CoM. Without wind the dummy rotates freely.

(Just FYI i'm using free moving joints from Infernal Robotics for this Oh i love this game so much)

Edited January 27, 2015 by DaMichel

[Kerbodyne Industries Rep]

Is there any way to enable FAR in 64x? I love the mod, but 32x can't use more than 4GB of RAM, so I can't have it in my super-modded save (180+ mods)

[BudgetHedgehog]

Is there any way to enable FAR in 64x? I love the mod, but 32x can't use more than 4GB of RAM, so I can't have it in my super-modded save (180+ mods)

Recompile it yourself without the x64 check or use Linux.

Edited January 27, 2015 by ObsessedWithKSP

[steve_v]

Is there any way to enable FAR in 64x? I love the mod, but 32x can't use more than 4GB of RAM, so I can't have it in my super-modded save (180+ mods)

A: Get monodevelop / visual studio, grab FAR source from github, remove the x64 check & recompile.

B: Install GNU/Linux

Edit: ninjad.

[ferram4]

@DaMichel: The problem is that for some reason, it's a pain to detect that parts are clipped together. For some reason, intakes are very prone to having problems with this. I'm not annoyed or offended with you, I'm annoyed with how things are. If you wanna take a crack at tweaking the inlet numbers and see if that causes things to behave better, be my guest; I'll keep working on a refactor to try and work around the entire source of the issue.

@HoneyFox: Yeah, the main thing with the curves is that it raises the question of where the moment is measured (the point in space) and whether you're accounting influence from other parts of the vehicle. Maybe the drag of a wing at 90 degrees simply isn't high enough; I don't know, I'll revisit it later.

@mecki: That is entirely DRE, and those fields should be there. They should be there for each and every part on your vehicle.

[Captain Planet]

Hey Ferram,

The latest version of a mod I used changed the models for the 1-man and 3-man crew capsules. Now, when they enter atmosphere, the top of the capsule forces itself prograde and refuses to budge. If you try to position it back the correct way (heatshield pointed forward), the craft vibrates itself to an explosion and all parts other than the capsule itself are stripped away and the camera goes into this fast unrecoverable spin. When I remove the FAR folder, this bizarre glitch doesn't happen anymore.

I'm not asking you to bugfix another person's mod, but have you encountered anything like this behavior before?

[HoneyFox]

HoneyFox (and Silverfox, too) you just gave me an awesome idea. Actual "wind tunnel" testing!

http://i.imgur.com/07AVm73.jpg

The strange Cm curve is not just a glitch in the graph. You can tell by the pitch control display that the 45 deg orientation is harder to hold than 90 deg.

I made sure that the axis of rotation goes through the CoM. Without wind the dummy rotates freely.

(Just FYI i'm using free moving joints from Infernal Robotics for this Oh i love this game so much)

this is a brilliant application of the free rotating dock-washing disc. I'm using the KerbalWind as well, but mainly for cross-wind take-off/landing challenges.

So you found that the aircraft needs to generate more pitch-up torque by these reaction wheels at alpha 45 than at 90 alpha to hold its attitude, right?

[Genius Evil]

Has the FARBasicDragModule changed with FAR for 0.90? Several parts I made which used it worked fine on my 0.25 install; but on 0.90 the FARBasicDragModules seem to have no effect. I created this cfg to see if something else was causing the issue:

Code:

PART

{

name = DRAGTEST

module = Part

author = BLA

//BLADES///////////////////////////////////////////////////////////////////////

MODEL {

model=AJE/VTProp/Blades/HSCOBlade1

position = 0.0, 0.1375, 0.0

scale = 1.69,1.69,1.69

rotation = 0, 0, 0

}

MODEL {

model=AJE/VTProp/Blades/HSCOBlade2

position = 0.0, 0.1375, 0.0

scale = 1.69,1.69,1.69

rotation = 0, 120, 0

}

MODEL {

model=AJE/VTProp/Blades/HSCOBlade3

position = 0.0, 0.1375, 0.0

scale = 1.69,1.69,1.69

rotation = 0, 240, 0

}

MODEL {

model=AJE/VTProp/Bits/Spinner

position = 0.0, 0.1375, 0.0

scale = 2.083,2.083,2.083

rotation = 0, 0, 0

}

//PROPERTIES///////////////////////////////////////////////////////////////////////

rescaleFactor = 1

node_stack_top = 0, 0, 0, 0, 1, 0, 1

///////////////////////////////////////////////////////////////////////////////////

TechRequired = aerodynamicSystems

entryCost = 2800

cost = 950

category = Propulsion

subcategory = 0

title = TEST

manufacturer = BLA

description = BLA

///////////////////////////////////////////////////////////////////////////////////

attachRules = 1,0,1,0,0

mass = 0.1

dragModelType = default

maximum_drag = 0

minimum_drag = 0

angularDrag = 0

crashTolerance = 7

maxTemp = 300

fuelCrossFeed = True

CoMOffset = 0, -1.2, 0

MODULE

{

name = FARBasicDragModel

S = 5.0

CdCurve

{

key = -1 0.004 0 0 // stern on

key = 0 0.001 0 0 // sideways

key = 1 0.003 0 0 // head on

}

ClPotentialCurve

{

key = -1 0 0 0

key = -0.5 -0.001 0 0

key = 0 0 0 0

key = 0.5 0.001 0 0

key = 1 0 0 0

}

CmCurve

{

key = -1 0.001 0 0

key = -0.5 0.0 0 0

key = 0 -0.001 0 0

key = 0.5 -0.002 0 0

key = 1 -0.004 0 0

}

ClViscousCurve

{

key = -1 0.0 0.0 0.0

key = 0.0 0.0 0.0 0.0

key = 1.0 0.0 0.0 0.0

}

}

}

In 0.25, this has the proper Cd of ~0.05, but in 0.90 it has a Cd of over 2. Changing the values in the cfg seems to have no effect in game. Is this just a problem with my install?

Just bumping this since it's been a couple days. I've tried reinstalling KSP and all mods, but FARBasicDragModel still does not seem to work with 0.90. I can use this cfg in 0.25 and it works perfectly, but in 0.90 the FARBasicDragModel has no effect on the part.

It really feels like an installation issue, but I started from scratch and still had the same issues. Could someone please tell me if I'm doing something wrong here?

[ferram4]

@Captain Planet: Nope, and without even knowing what mod it is, there's no way for me to troubleshoot it.

@Genius Evil: FARBasicDragModel works perfectly fine. FARBasicDragModel is exactly what FAR has always used to apply drag to parts, and all tests indicate that it is functioning properly.

The problem is that you have not provided any information about what differentiates your part from any other one. In particular, why do you need a manually-defined FARBasicDragModel, considering that there are many propeller engines that function perfectly with FAR? What are you doing differently than them?

[Captain Planet]

@Captain Planet: Nope, and without even knowing what mod it is, there's no way for me to troubleshoot it.

It's Ven's Stock Revamp version 1.7.1.

Edited January 28, 2015 by Captain Planet

[SeventhArchitect]

So, I took out the...stapledon. From b9 aerospace. Perfect spaceplane to carry a payload I needed in orbit.

Can't get past 7,000 meters (height).

So. I got it off the runway half assedly. That right there was a big relief to see those back wheels actually leave the ground (the front wheel left the ground before the engines fired, yikes, dat off kilter mass). The stapeldon flew great until at one random point, it started to throw itself in turns that were way to fast for the ship to manage at all. Especially with fAR involved, and especially since it was so big. Ic ut the engines, turned off the sas, then let it glide, righted it, turned sas back on, fired the engines, got it to start flying again. Well. Hit 7km high (watched the meter), and it started doing weird flips again.

I do not know whether to contact B( aerospace or FAR, but I will post on both for obvious reasons. With this taking palce, Ic an't use the stapledon to go higher than 7 kilometers. I coudl probably manage to launch somethign traditional. Lots of boosters method always worked.

I literally had no problems until the 7 km mark.

- - - Updated - - -

or not, seems the b9 aerospace thread is clsoed. :/

[blowfish]

So, I took out the...stapledon. From b9 aerospace. Perfect spaceplane to carry a payload I needed in orbit.

Can't get past 7,000 meters (height).

So. I got it off the runway half assedly. That right there was a big relief to see those back wheels actually leave the ground (the front wheel left the ground before the engines fired, yikes, dat off kilter mass). The stapeldon flew great until at one random point, it started to throw itself in turns that were way to fast for the ship to manage at all. Especially with fAR involved, and especially since it was so big. Ic ut the engines, turned off the sas, then let it glide, righted it, turned sas back on, fired the engines, got it to start flying again. Well. Hit 7km high (watched the meter), and it started doing weird flips again.

I do not know whether to contact B( aerospace or FAR, but I will post on both for obvious reasons. With this taking palce, Ic an't use the stapledon to go higher than 7 kilometers. I coudl probably manage to launch somethign traditional. Lots of boosters method always worked.

I literally had no problems until the 7 km mark.

- - - Updated - - -

or not, seems the b9 aerospace thread is clsoed. :/

None of the stock B9 craft have been balanced in a while. FAR underwent some major changes recently (adjustments to wing code, high mach skin drag) which could easily account for this.

And the B9 thread looks fine to me.