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

[Guest]

I've got a problem with Soyuz payload fairings from BobCat's pack. I changed all instances of "Shroud" to "Fairing" in them, and even added "Fairing" to LES that forms the top part. Still, all parts on the Soyuz show up as "isShielded: false".

[praise the suuun]

Hello ferram aerospace! i have a question concerning tail planes / vertical stabilizers. im designing and filming but i dont have time to learn the tried n' true equations for pitching moments, COG, COL but i can guesstimate those last two.

anyways i just need to know how vertical stabilizers can push the see saw of the COG downwards when its flat surfaces would be influencing the flow of the air to become heavier than below the tail. how does that generate stability?

i would also like to know if engines mounted at the very top of the vertical stabilizers are possible in a custom design.

best wishes to you FAR and thanks for the outstanding mod!

[localSol]

[...] Here are the "FAR lines" at Mach 6:

Notice the center of lift has been moved further back, so the pitching moment (yellow line) has been reduced drastically in relation to the B9 wing.[...]

Good post. It had me taking another look at pitching moment (Cm) in the graphs for my planes, that I overlook often.

Anyone know what mod/plugin the Red Sphere is in these pictures, and what it does?

[ferram4]

@Dragon01: I'm investigating. Hopefully it's something easy to fix.

@praise the suuun: Vertical stabilizers do very little to affect pitch stability or to affect where the center of mass is; the only have significant effects on yaw stability. Horizontal stabilizers do help affect pitch stability by creating lift behind the center of mass, helping to tilt the plane into the airflow properly.

Yes, it is possible to attach engines to the tops of vertical tails with this (it always was possible, even in stock KSP) but the pitch-down moment you'll get from that under thrust will probably be highly undesirable.

[softweir]

...

Anyone know what mod/plugin the Red Sphere is in these pictures, and what it does?

http://forum.kerbalspaceprogram.com/threads/35996-0-22-RCS-Build-Aid-v0-4-For-balanced-placement-of-RCS-GUI-added?highlight=rcsbuildaid

The red Sphere shows the CoM when all tanks are drained. The mod also shows turning moments produced when using RCS translation, making it easier to place thrusters so as to minimise wobble when docking.

[localSol]

http://forum.kerbalspaceprogram.com/threads/35996-0-22-RCS-Build-Aid-v0-4-For-balanced-placement-of-RCS-GUI-added?highlight=rcsbuildaid

The red Sphere shows the CoM when all tanks are drained. The mod also shows turning moments produced when using RCS translation, making it easier to place thrusters so as to minimise wobble when docking.

Thanks a metric kerbalton. This will go very well helping me to make better planes for FAR too!

[Guest]

Ferram, I'd like to ask you, can engines be counted as fairings? Most BobCat's payload fairings have built-in separation motors. On Soyuz, the bottom fairing half turned out to be properly recognized, while the top one (containing animated airbrakes and sep engines) was not. I'll check if removing the engines does anything, but I'd rather see it fixed in the plugin. On Soyuz, I don't think those sep motors actually contribute to separation in any meaningful way, but for example on N1, they're absolutely vital to a proper shroud jettison.

Edited November 3, 2013 by Guest

[SZDarkhack]

I'm using FAR with Real Solar System and DREC. When I deorbited a spent stage yesterday, it seemed to come to equilibrium in a strange attitude. I managed to get another stage in that configuration (which is harder than it sounds with the mouse bug and what not; by the way switching to a different vessel in map view seems to "fix" it without the need to restart KSP). Here's a screenshot (just in time too, DREC destroyed it a second later )

Since I'm not an expert in aerodynamics, I would like to know if this is indeed (realistically) a stable configuration (it seems weird to me). Note that it is a stable equilibrium, i.e. although it was wobbling a bit it would "gravitate" back to this position.

[Surefoot]

The tank is empty and the engine is heavy, so it's going in front, just like with rockets.

[SZDarkhack]

The tank is empty and the engine is heavy, so it's going in front, just like with rockets.

Notice that the attitude is not aligned with the retrograde vector (which is what I would expect for a tail-heavy object). It WANTED to stay at this angle of attack. That's what's confusing me.

[camlost]

Notice that the attitude is not aligned with the retrograde vector (which is what I would expect for a tail-heavy object). It WANTED to stay at this angle of attack. That's what's confusing me.

May I ask how did you print orbital information on the screen?

[Surefoot]

I guess this is because the engine itself has a very high drag compared to the fuel tank - so the fuel tank would want to go in front as well, and it reaches equilibrium where the engine points down due to gravity.

[a.g.]

What's on top of that thing? It is hard to see due to re-entry effects.

[SZDarkhack]

May I ask how did you print orbital information on the screen?

VOID.

@Surefoot: That makes sense. Interesting effect: The previous stage that got stuck this way was backwards, i.e. engine back, so it was angled upwards. Result? It skipped out of the atmosphere twice and survived the entire reentry unshielded

[Flyingbear]

Was your SAS trying to keep some other orientation while you were going into atmo?

[SZDarkhack]

Was your SAS trying to keep some other orientation while you were going into atmo?

This is a spent stage, the SAS indicator is on from the time it was still attached to the payload. There is no control on it whatsoever.

[AbeS]

I noticed your navball was in orbit mode, did you check on surface mode? Because orbital and surface retrogrades are different most of the time!

[Surefoot]

The re-entry effects point in the right direction according to the navball... As for the ricochet nice one, if one wanted to do one willingly it wouldnt be a piece of cake !

[a.g.]

It seems this may be because of attach node drag. Note how it has two stable equilibrium points at +-25 degrees AoA, but once I cap off the engine, it turns into one stable position at engine forward. Capping of the other end improves stability even more.

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[KerbMav]

A few questions:

Would this be correct to update all mod parachutes (that use the same MODULE) for FAR?

@PART[*]:HAS[@MODULE[ModuleParachute]]
{
	@MODULE[ModuleParachute]
	{
		@stowedDrag = 0
	}

How could drag be added for extended landing gears ?

Would planes then go into nose dive or would the rear landing gear balance it out?

Which mods (parts) are supported or which ones add their own cfg to be compatible with FAR - will a mod always work with FAR as long as it does not add wings or control surfaces?

Could there be problems with parts "looking" aerodynamically, but having just a square collision box?

Does anything have to be changed regarding the updated behaviour (adding stability by modified drag values) of the new .22 cones?

[a.g.]

Landing gears that use the stock module don't actually exist physically, so they can't have any mass or drag.

All parts are modelled as basically a cylinder or cone segment, so the most important part is that FAR gets the axis orientation right. All stock parts are aligned so that their main axis is vertical when the part is displayed in VAB menu; if that is not correct for a part, it may cause problems unless some heuristics in FAR (based on attach nodes or intake direction) manage to correct for it.

[SZDarkhack]

It seems this may be because of attach node drag. Note how it has two stable equilibrium points at +-25 degrees AoA, but once I cap off the engine, it turns into one stable position at engine forward. Capping of the other end improves stability even more.

I completely forgot about the static analysis... This is very interesting though, so there is indeed a proper aerodynamic reason for this effect. Thanks for working that out, I'll keep the tools in mind for the future

[Taverius]

Does anything have to be changed regarding the updated behaviour (adding stability by modified drag values) of the new .22 cones?

All the did was lower the drag to 0.1 - nothing actually changed. Heck, some nosecones already had the drag at 0.1 since like 0.16, and did you notice them working 'properly' with the stock model before?

[KerbMav]

All the did was lower the drag to 0.1 - nothing actually changed. Heck, some nosecones already had the drag at 0.1 since like 0.16, and did you notice them working 'properly' with the stock model before?

Hmmm ...

Landing gears that use the stock module don't actually exist physically, so they can't have any mass or drag.

Bummer.

All parts are modelled as basically a cylinder or cone segment, so the most important part is that FAR gets the axis orientation right. All stock parts are aligned so that their main axis is vertical when the part is displayed in VAB menu; if that is not correct for a part, it may cause problems unless some heuristics in FAR (based on attach nodes or intake direction) manage to correct for it.

Sooo ... how does FAR then make a tank more aerodynamic when using a cone?

I mean, would it not have the same effect to change a cylinder-tank to a cone-tank?

Curious with all the numbers added by MM to the wings etc. is that I was able to gain altitude while screaming at 2km/s+ through Kerbins atmosphere by simply raising the nose of my lander above the horizon - no control surfaces involved.

[Hogdriver]

Hey ferram4,

it seems you forgot to comment out a debug print in FARBasicDragModel.cs:372

print(part.partInfo.title + " Part Loc: " + part.transform.position + " Attach Loc: " + (origToNode + part.transform.position) + " Dist: " + mag);

That makes my game stutter quite a bit if i build anything biggish. Love your mod btw, keep up the good work :-)