[WIP] R.E.L Skylon C2. Alpha Released. FAR config broken. (08 Dec 2014)

[CaptainKipard]

Yeah, when IntakeAir gets really low, it just drops the rest of the way at about 20km. I thought that was normal behaviour.

[ozraven]

Cpt. Kipard, your Skylon is well on its way to being a whole new aspect to KSP, for me. Since you released the Alpha, I have been following the thread and playing with the Skylon myself, hoping to have some useful feedback to contribute:

(I'm testing with KSP 0.25 (32-bit) on Windows, DRE and MM installed.)

1. I noticed MechJeb wasn't able to execute burn maneuvers, and later that dV and other engine statistics weren't being reported properly. I did some looking, and then sarbian suggested a quick fix, which worked. The trouble was with the multiple ModuleGimbal in the Sabre engine. The fix is available in MechJeb dev build 353. (Let it be known that if someone creates an engine exotic enough to make multiple gimbals actually affect the engine's performance, they should plan to fly manually! )
   
2. I've been testing with DRE installed and using a B9/SPP-derived configuration in MM patch form. Ascent can make things hot getting to 950-1000m/s right at 20km, so it seems that at ~18km levelling out and throttle down 5-10% to prolong intake function helps; then switching to closed cycle about 22-23km and really try to get UP quick from there. I'm still working on reentry - has anyone come across Skylon's reentry profile?
   
3. During takeoff, I have to correct for a bit of a pull to the right.
   
4. At high altitude, above 20km during final moments of air breathing and then after closed circuit switch, Skylon wants to roll and yaw to the left a bit.
   
5. Do you intend, or would it be possible to make the landing light on the nose gear controllable via Action Group?
   
6. I tried White Owl's post with aero/mass adjustments and I find Skylon is a bit harder to handle climbing through the 18-20km range, for me.
   

Edited December 6, 2014 by ozraven

[CaptainKipard]

FAR/NEAR config for wings and control surfaces.

I haven't tested it yet.

@PART[KipEngSkylonWing*]:NEEDS[FerramAerospaceResearch|NEAR]

{

// zero out all stock values, remove stock module

@module = Part

@maximum_drag = 0

@minimum_drag = 0

@angularDrag = 0

@dragCoeff = 0

@deflectionLiftCoeff = 0

@ctrlSurfaceRange = 0

@ctrlSurfaceArea = 0

// add custom FAR values

MODULE

{

name = FARControllableSurface

MAC = 10.385

MidChordSweep = 17.165

b_2 = 4.02

TaperRatio = 0.56

e = 0.87

nonSideAttach = 0

maxdeflect = 15

ctrlSurfFrac = 0.12

}

}

@PART[KipEngSkylonCanard*]:NEEDS[FerramAerospaceResearch|NEAR]

{

// zero out all stock values, remove stock module

@module = Part

@maximum_drag = 0

@minimum_drag = 0

@angularDrag = 0

@dragCoeff = 0

@deflectionLiftCoeff = 0

@ctrlSurfaceRange = 0

@ctrlSurfaceArea = 0

// add custom FAR values

MODULE

{

name = FARControllableSurface

MAC = 1.985

MidChordSweep = 42.695

b_2 = 4.02

TaperRatio = 0.25

e = 0.87

nonSideAttach = 0

maxdeflect = 15

ctrlSurfFrac = 1

}

}

@PART[KipEngSkylonStabiliser]:NEEDS[FerramAerospaceResearch|NEAR]

{

// zero out all stock values, remove stock module

@module = Part

@maximum_drag = 0

@minimum_drag = 0

@angularDrag = 0

@dragCoeff = 0

@deflectionLiftCoeff = 0

@ctrlSurfaceRange = 0

@ctrlSurfaceArea = 0

// add custom FAR values

MODULE

{

name = FARControllableSurface

MAC = 3.27

MidChordSweep = 44.227

b_2 = 4.02

TaperRatio = 0.213

e = 0.87

nonSideAttach = 0

maxdeflect = 15

ctrlSurfFrac = 1

}

}

@PART[KipEngSkylonSabreEngine]:NEEDS[FerramAerospaceResearch]:AFTER[FerramAerospaceResearch]:NEEDS[!AJE]

{

@MODULE[ModuleEnginesFX],0

{

@maxThrust *= 1.5

}

}

I've been testing with DRE installed and using a B9/SPP-derived configuration in MM patch form. Ascent can make things hot getting to 950-1000m/s right at 20km, so it seems that at ~18km levelling out and throttle down 5-10% to prolong intake function helps; then switching to closed cycle about 22-23km and really try to get UP quick from there. I'm still working on reentry - has anyone come across Skylon's reentry profile?

Have a look on RELs website. Their manual includes a lot of info including flight a profile in the form of a time/altitude graph.

During takeoff, I have to correct for a bit of a pull to the right.

I suspect this is because of wonky wheel stack nodes. I can't do much about that.

At high altitude, above 20km during final moments of air breathing and then after closed circuit switch, Skylon wants to roll and yaw to the left a bit.

That's because one of the engines is getting less IntakeAir, and at that altitude it's causing asymmetrical thrust. By that time you should be in rocket mode anyway.

This happens with stock arcraft too, so I don't know what to do about it.

Do you intend, or would it be possible to make the landing light on the nose gear controllable via Action Group?

Do you want it off when deployed?

I tried White Owl's post with aero/mass adjustments and I find Skylon is a bit harder to handle climbing through the 18-20km range, for me.

I can't help you there. It works great for me.

Edited December 7, 2014 by Cpt. Kipard
FAR Config updated

[Climberfx]

Cool Cpt. Gonna test right a way!

[White Owl]

Yeah, when IntakeAir gets really low, it just drops the rest of the way at about 20km. I thought that was normal behaviour.

It's not a huge issue; the plane is still perfectly usable. I just wonder why I see different behavior when using two vehicles that should in theory be identical. No idea.

[CaptainKipard]

There ware some typos in that config. Fixed now.

Edited December 6, 2014 by Cpt. Kipard

[Climberfx]

I couldn't even take off with the FAR new settings.

It lost control nagging on wheels in the runway, i try manual on joystick, smooth, i try mj vertical velocity with little pitch increments, i try surface velocity with a given 10, 15º 20º, and in all cases, lost control, from left to right gear and crash.

I try with and without SAS.

It could pitch before the end of runway, but lost control disestablishing from left to right and so on.

All this tests with 10k on each of 3 tanks, and the default cargo.

[piggysanTH]

Skylon part don't show in VAB;.; Any fix?

[sirkut]

Skylon part don't show in VAB;.; Any fix?

Look at your log file. You must be doing something wrong.

[Enterprise0709]

So i took the stock craft for a few test flights (Stock KSP) this are some of the things i noticed from takeoff to landing:

Even with a 36 tons payload she gets up into space really easy (Perhaps a bit too easy?). Got her in a 200x200km orbit just fine with quite a bit of fuel to spare.

She has very little torque for a ship this size and mass, so that has little use in orbit. You'll have to use RCS for rotation in orbit. However, she burns through her 200 units of monopropellant at an alarming rate. The Orbital Maneuvering System is just plain useless. According to Kerbal Engineer it only provides a TWR of .10. Thats without payload, and hydrogen and oxygen reserves reduced to half. Having the same level of Specific Impulse as the SABRE engines doesn't help improve the SOMS usefulnesses either. Might as-well use the SABRE engines instead.

Landing it is an absolute nightmare! You'll have to use SABRE engines in order to land it, because once disabled the craft will flip out of control in a matter of seconds. Something to do with the CoL in front of the CoM? Or maybe I'm just doing it wrong.

Anyways thats just the observations of an average KSP player, sorry if i mentioned stuff that has been mentioned before. Looks fine though! Even if she tries to kill me while attempting an unpowered landing!

Edited December 6, 2014 by Enterprise0709

[ozraven]

Have a look on RELs website. Their manual includes a lot of info including flight a profile in the form of a time/altitude graph.

Cool. You're right - I knew I had seen some info on that somewhere, but in haste I overlooked it. Thanks, will do, and I'll see if I can make the DRE config as suitable to the information they have.

I suspect this is because of wonky wheel stack nodes. I can't do much about that.

Cool, it's certainly not insurmountable, just a little nudge or two and she's true enough to get the nose up.

That's because one of the engines is getting less IntakeAir, and at that altitude it's causing asymmetrical thrust. By that time you should be in rocket mode anyway.

This happens with stock arcraft too, so I don't know what to do about it.

Of course. I've done a fair bit of (relatively) high altitude flight, but very little with SSTOs, so I'm not used to seeing the continuing effects. I don't think there's anything to be done - unless a useful benefit to the precooler can be achieved. Perhaps a custom module could combine IntakeAir, airspeed, and some handwaving to "amplify" the amount of IntakeAir available for the engines. This may help in getting up a bit higher, while still in the 0.9-1.0km/s range to avoid excessive heating on ascent. (My earliest DRE settings had a problem burning up the nose tank.)

Do you want it off when deployed?

Just setup as an available action would be cool, like the stock Small Gear Bay's light, so it can be controlled independently.

I can't help you there. It works great for me.

No worries. Likely a pilot issue.

[Climberfx]

Cpt Kepard.

I put module manager CFG file you described here, and it's not working. I think it's putting lift on only left wings side, because the moment it take of, it spin clockwise uncontrollable.

Is that possible to miss some part on that cfg?

Skylon part don't show in VAB;.; Any fix?

Piggysan, if you are in Career mode, have you checked the RD (Research and Development) for the new parts? You need to inicialize then if is your first use.

I have here the auto research mod, that do that for me on start.

Some pics to show how is showing COM and COL on SPH after FAR cfg. I make some combinations to help to isolate the problem.

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr*

This one showed that without any wing, front and back, the center of lift still on middle, the right position.

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

Skylon COM, COL by Climberfx, on Flickr

EDIT:

I think this happens because FAR formulas are made to work with rotate objects symmetry. In Skylon we don't have symmetry mode, but two types of wing, left and right. But this is only a supposition.

I know that this is not the correct way, but if you change onnonSideAttach from 0 to 1 (I know this is not a tip of the wing) it fix the center of Lift on the SPH, and turn the ship flyable. But not stable.

Edited December 7, 2014 by Climberfx

[CaptainKipard]

I don't have this issue.

About the sluggishness.

I'd welcome some input from a modder who made stuff for FAR before. Contrary to expectations the craft performs worse now than in stock. Lower TWR, less lift (although that's understandable).

The low TWR is particularly alarming, and very surprising. Why would that happen?

edit

I'm just looking at the Sabre in the SPH parts list, and it shows the thrust to be much lower than it had been (exactly half). Why did that happen? The config says 1960. The tooltip says 980. This is probably the reason for poor performance.

Edited December 6, 2014 by Cpt. Kipard

[Climberfx]

Yep, on air breathing mode i have the same here. And is the same on B9 Sabre engines, they have on cfg file, double the power that there is on the game.

But i'm surprised that this issue of COL of center not happens with you. Why is only on mine. I have all right here...

Well, gonna dig some more...

EDIT:

Find the problem of help power on jets. Is a config that B9 made a long time ago, to underpowered squad turbojet by 50% and overpower squad normal jet by 1.04x.

Because that confit, it put your jet in half power.

To not mess with this B9 config, i recommend you to put the double the power, if a person have B9 installed.

"// B9 Aerospace - nerf squad jets for great justice file..."

Edited December 6, 2014 by Climberfx

[CaptainKipard]

I'm using the latest FAR release, if that helps.

[Climberfx]

I'm using 14.4 too...

[CaptainKipard]

I looked through the FAR MM config and I found this.

@PART[*]:HAS[@MODULE[ModuleEngines*]:HAS[@PROPELLANT[intakeAir]]]:BEFORE[FerramAerospaceResearch]:NEEDS[!AJE]

{

@MODULE[ModuleEngines*]

{

@maxThrust *= 0.5

}

}

It divides the thrust by 2 of every part that uses IntakeAir.

I'll need to undo that in my own MM config somehow.

Also FAR calculates drag based on stack nodes, so I need to fix some of those.

Edited December 6, 2014 by Cpt. Kipard

[Climberfx]

hum, that was not B9 so. Ok, doing that too...

If you put

@PART[KipEngSkylonSabreEngine]:HAS[FerramAerospaceResearch]
{
     @MODULE[ModuleEnginesFX]
     {
          @maxThrust*=2
     }
}

That should do auto correction on every user that put FAR and use your mod.

Edited December 6, 2014 by Climberfx

[CaptainKipard]

That'll multiply the thrust of both modes. I think it needs to be this:

@PART[KipEngSkylonSabreEngine]:HAS[@MODULE[ModuleEngines*]:HAS[@PROPELLANT[IntakeAir]]]:NEEDS[FerramAerospaceResearch]:AFTER[FerramAerospaceResearch]:NEEDS[!AJE]
{
	@MODULE[ModuleEngines*]
	{
		@maxThrust *= 2
	}
}

This should only change the value of the ModuleEngineFX which contains IntakeAir, which means the air-breathing mode. I Also have to apply this patch after FAR applied its patch.

[Climberfx]

Ok, applying that, but i reinstall far and i'm still if that unbalanced COL.

[CaptainKipard]

For future reference if you haven't already then install RCS Build Aid. It makes balancing of everything very easy. Contrary to its name, it helps with regular engines too

[blowfish]

You can reference the two engine modules separately by index:

@MODULE[ModuleEnginesFX],0 {}

[Climberfx]

Doing a clean install from ZERO on every one of the dependencies and KSP from site too.

That manner i you know for sure if is a conflict or a local thing on Mac...

Edited December 7, 2014 by Climberfx

[Voculus]

Climberfx, I'm seeing the same thing in the SPH as you are.

In any event, awesome job on the Skylon, Kipard! Very impressive. I was surprised at just how big it was!

[CaptainKipard]

Climberfx, I'm seeing the same thing in the SPH as you are.

In any event, awesome job on the Skylon, Kipard! Very impressive. I was surprised at just how big it was!

Are you on a Mac?

Are you using latest releases of everything?

BTW the real Skylon is even bigger than this. I had to scale it down for game purposes.

Edited December 7, 2014 by Cpt. Kipard