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

[Volt]

Volt, you're not going very fast. Seems about right.

Ahh, good. I was thinking maybe they were outrageously low, because that plane climbs like a dream and gains speed in a dive like you wouldn't believe, but then again this is the first time I've succeeded in building a large-body jet, so maybe they all have those energy characteristics? I was also suspicious of B9, because I've been having no end of peculiar glitches with the 0.23.5 fix versions, mainly involving the mass of some of the parts being NaN (oh the humanity...) and messing with analyses, but I don't know if they cause any further troubles.

[MAKC]

WOW! The dynamic pressure changes really make a big difference. I got the Hypersonic Demon to mach 2+ at sea level and anything more than a slight tap caused it to lose wingtips, then wings, then disintigrate and blow up the cockpit in mid-flight.

Use trim to control attitude at supersonic speeds. Alt + WASD. Alt + X resets the trim.

[Starwaster]

Ahh, good. I was thinking maybe they were outrageously low, because that plane climbs like a dream and gains speed in a dive like you wouldn't believe, but then again this is the first time I've succeeded in building a large-body jet, so maybe they all have those energy characteristics? I was also suspicious of B9, because I've been having no end of peculiar glitches with the 0.23.5 fix versions, mainly involving the mass of some of the parts being NaN (oh the humanity...) and messing with analyses, but I don't know if they cause any further troubles.

For me, gaining lots of speed in a dive is usually accompanied by flat spins, followed by the yelling and the screaming.

[Bird-e]

Has anyone else experienced an odd bug while using FAR in craft that have been recently detached (not detached, specifically undocked) where pitch and roll controls stop working entirely? It's a very odd bug, but I tracked it down to FAR a while ago, and I still haven't been able to figure out why it does that. I haven't seen any mention of it in this thread, nor has FAR been updated in a while, so it's possibly a mod conflict, but I have no idea.

Use trim to control attitude at supersonic speeds. Alt + WASD. Alt + X resets the trim.

Wowwwwwww. I could've saved hours of time minutely trimming craft if I'd known this sooner haha.

[Woodstar]

I'm wondering if someone here in this thread can help me with a problem, I recently downloaded the Spaceplane plus mod and it comes with a FAR.cfg that a fellow forum user brought to my attention that it is not so FAR friendly. I was wondering if some one can fix it for me?

Here is the config

@PART[wingConnector2]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	MODULE
	{
		name = FARWingAerodynamicModel
		MAC = 2 //Mean chord length in meters
		e = 0.75 //Drag per lift, lower equals more drag
		MidChordSweep = 0 //Angle of line from mid root chord to mid tip chord
		b_2 = 3.76 //Root to tip in meters
		TaperRatio = 1 //Ratio of tip chord to root chord
	}
}

@PART[wingConnector3]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	MODULE
	{
		name = FARWingAerodynamicModel
		MAC = 1 //Mean chord length in meters
		e = 0.75 //Drag per lift, lower equals more drag
		MidChordSweep = 0 //Angle of line from mid root chord to mid tip chord
		b_2 = 1.88 //Root to tip in meters
		TaperRatio = 1 //Ratio of tip chord to root chord
	}
}

@PART[wingConnector4]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	MODULE
	{
		name = FARWingAerodynamicModel
		MAC = 1 //Mean chord length in meters
		e = 0.75 //Drag per lift, lower equals more drag
		MidChordSweep = 0 //Angle of line from mid root chord to mid tip chord
		b_2 = 0.95 //Root to tip in meters
		TaperRatio = 1 //Ratio of tip chord to root chord
	}
}
@PART[elevon1]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	@ctrlSurfaceRange = 0
	@ctrlSurfaceArea = 0
	MODULE
	{
		name = FARControllableSurface
		MAC = 0.5
		e = 0.9
		nonSideAttach = 1
		maxdeflect = 15
		MidChordSweep = 0
		b_2 = 1.8
		TaperRatio = 1
	}
}
@PART[elevon2]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	@ctrlSurfaceRange = 0
	@ctrlSurfaceArea = 0
	MODULE
	{
		name = FARControllableSurface
		MAC = 0.62
		e = 0.9
		nonSideAttach = 1
		maxdeflect = 15
		MidChordSweep = -4
		b_2 = 1.8
		TaperRatio = 0.67
	}
}
@PART[elevon3]
{
	@module = Part
	@maximum_drag = 0
	@minimum_drag = 0
	@angularDrag = 0
	@dragCoeff = 0
	@deflectionLiftCoeff = 0
	@ctrlSurfaceRange = 0
	@ctrlSurfaceArea = 0
	MODULE
	{
		name = FARControllableSurface
		MAC = 0.86
		e = 0.9
		nonSideAttach = 1
		maxdeflect = 15
		MidChordSweep = -4
		b_2 = 1.8
		TaperRatio = 0.75
	}
}

Edited May 25, 2014 by Woodstar

[ferram4]

@Bird-e: I'm not so sure that would be FAR, unless you had FAR's control systems activated in some way during undocking (in which case I would wonder why you had them on in orbit to begin with). That said, I need specific reproduction steps and a copy of the output_log.txt to do anything about it.

@Woodstar: Those configs look perfectly fine. What is your issue, are the wings making incorrect amounts of lift and drag for their size?

[phoenix_ca]

@Woodstar: Those configs look perfectly fine. What is your issue, are the wings making incorrect amounts of lift and drag for their size?

You can read that!?!

Woodstar, there are code tags you can use: [ code] [ /code] (sans spaces)

[Woodstar]

@Woodstar: Those configs look perfectly fine. What is your issue, are the wings making incorrect amounts of lift and drag for their size?

I'm not to sure I know when i get at 120-150 m/s and lift off the whole plane just rips apart like I Elmer's glued it together. I also posted in the Spaceplane plus thread so I'm not sure if it is FAR or maybe a joint problem with his parts. still waiting on a reply over there.

@ Phoenix_ca Sorry added code tag, I tried with spoiler tags and it didn't work, totally forgot about code tags, brain fart i guess.

Edit: This is what I was told in the SP+ thread.

Are you using anything to make the SP+ parts More compatible with FAR?

If not look around... I think the development thread. The wings and control surfaces can benefit from decent configs and the fuselage parts are configured as module = Winglet instead of Part, which doesnt work so well with FAR.

Maybe ask Joachim if he's using such a config.

Edited May 25, 2014 by Woodstar

[ferram4]

Then it sounds like this is intended behavior. Your take off velocity is too high, and you should attempt to build a plane with more wing area / less mass / better ability to rotate on the runway so that it can take off at a lower speed. For comparison, the F-104 had pretty much the highest takeoff velocity I an think of, and that took off at 190 knots (97 m/s). If you're pitching up like a maniac shortly after taking off, then the plane is supposed to come apart; overstressing the airframe like that causes bad things to happen.

[Volt]

For me, gaining lots of speed in a dive is usually accompanied by flat spins, followed by the yelling and the screaming.

...and the glaivin'? That is an odd behaviour, are you pulling up hard into an accelerated stall or something?

[Drew Kerman]

I'm looking to get the Coffee Industries wings to work with FAR. I've checked out the .cfg sample in the ReadMe but still not sure how to figure out some of the values. I'm guessing some of it needs to be done in a modeler so I can see what length things are better? For example "distance from wing root to tip; semi-span" would be in meters? I checked out the equation for MAC and it is math beyond me :/ Not sure I'm up to this but willing to try and learn...

[Woodstar]

Then it sounds like this is intended behavior. Your take off velocity is too high, and you should attempt to build a plane with more wing area / less mass / better ability to rotate on the runway so that it can take off at a lower speed. For comparison, the F-104 had pretty much the highest takeoff velocity I an think of, and that took off at 190 knots (97 m/s). If you're pitching up like a maniac shortly after taking off, then the plane is supposed to come apart; overstressing the airframe like that causes bad things to happen.

Yup I rebuilt it last night, and from what I can tell I just actually had too much wing for my take off speed, gave it a smaller yet longer not so wide delta style wing and she just bolted into the upper atmosphere, thanks for the help and patience with me!

[Starwaster]

...and the glaivin'? That is an odd behaviour, are you pulling up hard into an accelerated stall or something?

......

what about the yelling and the screaming, was that odd too???

[whynot]

Hello! I keep getting this weird behaviour:

The center of pressure ends up in a very unintuituve location.

The problem goes away if I uninstall FAR. I do not want to uninstall FAR, it's awesome.

Mods used on the pictured craft are procedural fairings and wings, all other parts are stock except for RemoteTech antennas and a MechJeb case in the fairing. All parts in the fairing indicate "shielded" as expected. I get no debug output.

I find the bug hard to reproduce. Sometimes the CoL behaves as expected, but most often it appears to be in the opposite end from where it should be if you want to go to space today. Editing the craft at this point, like trying to re-attach the fins, will generally cause the blue marker to disappear.

Feel free to ask if there is any more information you need. Cheers.

[MAKC]

Hello! I keep getting this weird behaviour:

Try detaching the fairings and flipping them upside down then reattach them.

Also double-check to make sure no fuel tanks are accidentally being shielded as that would mess up the CoP a lot.

[Taverius]

I'm looking to get the Coffee Industries wings to work with FAR. I've checked out the .cfg sample in the ReadMe but still not sure how to figure out some of the values. I'm guessing some of it needs to be done in a modeler so I can see what length things are better? For example "distance from wing root to tip; semi-span" would be in meters? I checked out the equation for MAC and it is math beyond me :/ Not sure I'm up to this but willing to try and learn...

That's a good point.

I'm going to put a little tutorial on the wiki with instructions on how to use blender to import the model and get 'accurate' measurements for FAR's trapezoidal approximation, the same way I did the values FAR uses for the stock wings.

In the meanwhile you want to install blender and taniwha's .mu importer for blender, you can find it in the tools forum.

[Drew Kerman]

most excellent. I will get right on with installing the tools so I'm ready when you have time to work up the tutorial. Thanks!!

[Taverius]

So it turns out I've been using Maya for so long I can't use blender to save my life.

Therefore, all I have is a short stub on the generics of how to approximate an wing's mesh. At least it will (hopefully) help you figure out b_2, MAC, and so on. There's an image! With colours!

Plus tips on several assumptions FAR makes one must keep in mind when doing this.

Hopefully someone more familiar with Blender will be able to write a more detailed step-by-step.

[Drew Kerman]

thanks. People aren't kidding when they say Blender's interface is insanely hard to grok, if great once you get to know it. I just figured out how to get the bloody addon installed

[Taverius]

Sure.

At a very basic, you can get the worldspace positions for the vertex in question with 'n' in edit mode and selecting world co-ordinates. You can also turn on angle lenghts, though you have to edit the colours in preferences because the defaults are an utterly useless unreadable colour.

I was trying to use the ruler to get angles, but the snap function is rubbish.

[Starwaster]

thanks. People aren't kidding when they say Blender's interface is insanely hard to grok, if great once you get to know it. I just figured out how to get the bloody addon installed

I tried to use it once. I gave up on it.

I use XSI/Softimage Mod Tool

[Drew Kerman]

Ok, I took at stab at the straight wing from Coffee Industries. Here's what I ended up with:

@PART[planeWingStraightN]
{
    @module = Part
    @maximum_drag = 0
    @minimum_drag = 0
    @angularDrag = 0
    @dragCoeff = 0
    @deflectionLiftCoeff = 0
    MODULE
    {
        name = FARControllableSurface
        MAC = 2.25  // Tip = 1.5m | Root = 3m
        e = 0.35 // Drag per lift, lower equals more drag
        MidChordSweep = 4.25 // Leading sweep 8.5*
        b_2 = 10 // Root to tip in meters
        TaperRatio = 0.5 // Ratio of tip chord to root chord
        nonSideAttach = 0  // 0 for canard-like / normal wing pieces, 1 for ctrlsurfaces attached to the back of other wing parts
        maxdeflect = 15  // Default maximum deflection value; only used by FARControlableSurface
        ctrlSurfFrac = 0.12 // Value from 0-1, percentage of the part that is a flap; only used by FARControlableSurface
    }
}

And here's how I did it:

Using the measure guide, I was able to get the width of the wing (10m) and the root (3m). I used the polygon to get the tip by sizing it under the wing and measuring it (1.5m) and I also used the polygon to get the leading sweep by sizing it under the top of the root and the top of the tip and then getting the diagonal to give me the triangle for which I plugged in the sides to get the angles, including the angle of the sweep (8.5*). Then I used the Area measurement Blender gave to divide the control surface/wing surface to get the ctrlSurfFrac (0.12). Then I used the equations on Taverius' wiki guide to get the rest.

The only thing I didn't really know what to do with was e. A larger wing should produce more lift but also more drag right? No idea really what this should be.

Once you all who know better help me get this worked out, I will update the wiki with better Blender instructions.

[Taverius]

Getting the right value for Oswald's Efficiency is really, really hard.

Here is an excerpt of a PM I sent ferram about it:

Stumbled onto this Mathematica function, from which I can see one method that isn't limited to 'Normal' AR values and doesn't require spline curves, Shevell's Method from 'Fundamentals of Flight".

s = 1 - 1.9316 * df_over_b.^2;
k = 0.375 * CD0;
sweep_corr = 1  -  0.02 * AR.^0.7 .* sweep.^2.2;

e_shev = sweep_corr./(pi*AR.*k + 1./(u.*s));

Where:

df_over_b is the fuselage diameter/width over wing span ratio, default to 0

CD0 is the parasite drag coefficient

sweep for this function is quarter-chord sweep, which we (meaning you) ought to be able to trig from mid-chord sweep

Its related to a lot of things that are not surface area. Essentially, copy whatever ferram gave a stock wing of the same general shape.

[whynot]

Try detaching the fairings and flipping them upside down then reattach them.

Also double-check to make sure no fuel tanks are accidentally being shielded as that would mess up the CoP a lot.

Yo, I forgot there are a couple of Procedural Parts solid rockets in the middle fairing (tiny ones, inverted for separation). It appears they are causing the problem. Not sure if it is a procedural parts or FAR issue then, but FAR definitely think the rockets are much larger than they actually are.

[Drew Kerman]

Essentially, copy whatever ferram gave a stock wing of the same general shape.

There isn't a stock wing close to this one I don't think. I will wait for ferram to weigh in on all this. Thanks a ton for your help so far!