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

[White Owl]

The cargo bay has reaction wheels with a fairly low torque value. Personally, I like how slowly it changes attitude in orbit. Seems more reasonable than most KSP spaceships.

When empty, it lands comfortably between 80-100 m/s surface speed. SAS is almost a necessity, however, due to pitch instability. I want to play with some configs, see if it's possible to improve the pitch stability without sacrificing anything important to the vehicle.

Edit: Did I say low torque value? It's 60! The Skylon is just so big, 60 seems low!

Edited December 5, 2014 by White Owl

[CaptainKipard]

Thanks for giving useful feedback White Owl.

For the last few weeks I've been gradually removing resources from the tanks after each test. The takeoff mass right now is only a little less than the real Skylon takeoff mass iirc, so I can safely remove more resources to keep the mass proportional to its scale. I'm aiming to achieve a 300km orbit with a heavy payload, with enough resources left to deorbit, and fly about a bit in the atmosphere. It's a higher orbit than what's realistic, but I think it should be appropriate for the game.

The ISP and thrust of both engines are exactly like the real ones, and not very much better than existing engines, both stock and mod ones, so I probably wont change that.

You're right the SOMA isn't very useful, I only included it for authenticity. One use of it can be to make small maneuvers without needing to tweak the Sabre thrust limiter.

I haven't tried landing it yet either, but recent tweaks allowed me to gain altitude while still on the runway, so a proper landing is entirely possible even at max mass.

I'm tweaking things continuously, so specific feedback is welcome.

edit

The cargo bay has reaction wheels with a fairly low torque value. Personally, I like how slowly it changes attitude in orbit. Seems more reasonable than most KSP spaceships.

Yes this is intentional. I'll increase it very slightly.

When empty, it lands comfortably between 80-100 m/s surface speed. SAS is almost a necessity, however, due to pitch instability. I want to play with some configs, see if it's possible to improve the pitch stability without sacrificing anything important to the vehicle.

I'll try moving some of the fuel from the tail tank to the nose tank, and tweak the masses of them.

Edited December 5, 2014 by Cpt. Kipard

[White Owl]

Yeah, maybe move some mass around a little bit... I got the impression from reading the manual that the CoM is supposed to be just slightly forward of the center of the payload bay, since they state payloads should always be mounted at the forward end. At the moment the CoM is slightly aft of center. But of course the CoM can't be much further from the landing gear or it won't rotate.

As a first test, I decreased the canards' deflectionLiftCoeff from 1.2 to 1.0 and that seemed to improve the CoL issue. And the plane still has plenty of pitch control. It can take off in just over half the runway length... I think you could get away with generally decreasing lift, contrary to what I and others were writing earlier.

[CaptainKipard]

I think you could get away with generally decreasing lift, contrary to what I and others were writing earlier.

Yes, now that the craft is lighter I can get away with lowering it.

Other thing i would consider, is to position the RCS truster in the extremes of the fuel tanks, if you wanna use then for rotational manoeuvres.

You're right. Actually some of the official REL videos show RCS thrusters firing, but only in two places I think (top of the nose, and bottom of the tail). I've not come across official info on where all the nozzles are yet, so I did this as a quick and temporary solution just so I could release it.

[Climberfx]

Cool, good to know. You should consider put only little roles on surface in the desired angles, not a salience of it...

Will contribute to aesthetics, this ship is full aesthetics.

In FAR, when i switch to rocket mode, need to put 1/3 trust, or it lose control power on pitch. But 1/3 is more than enough to reach orbit, giving the reality that i can reach 1200 on air until near 25k, 28k..., when i switch it to rocket.

I don't know if this is the oficial power of it, but i think it is too much. Is more then twice of its air mode. But maybe is the real life torque, is it?

I had to put more vector trust on sabre to work on FAR, and adjust a little bit the COM, changing some weight parts, pushing it a little bit back, more near of COM. And this first orbit, i did with 10k on each tank. (3 of then), reaching orbit resting around a quarter tank. This seams good.

For the tail little rocket SOMA, i love it. If it have a better trust/fuel consumption ratio than the sabres, it will have more purpose, even letting the Skylon go to mun orbit (Is that too much?)

Loving the laboratory.

Here to help, but if i'm boring you, just say and i shut up!

Edited December 5, 2014 by Climberfx

[blowfish]

IIRC the engines are throttled down in rocket mode to limit acceleration to 1g. Not sure about pitch issues though.

[White Owl]

Try this out. I moved a couple tons of mass forward and decreased the canard lift a little bit more.

Canard deflectionLiftCoeff = 0.8

SkylonNoseFuel mass = 9.5

SkylonTailFuel mass = 5.5

SkylonNoseMP mass = 1.5

SkylonTailMP mass = 0.5

So I didn't touch overall mass or resources, just the balance. Now the CoM is right in the middle of the payload bay, and the CoL is ever so slightly behind the CoM. The plane is slightly more sluggish to lift the nose but still takes off well before the end of the runway. Try flying it around. You can set a desired pitch angle and it will stay there, with the SAS off.

[CaptainKipard]

Loving the laboratory.

What's that?

Try this out.

It works great.

[White Owl]

I changed a few more things and am flying a mission to deliver a big orange tank to 300km. Decided to try the orbital engine for fine maneuvers, but ran into a big problem: no gimbal. If the burn lasts any more than 10 seconds or so, then the reaction wheels can't keep the vehicle pointing straight.

I don't recall right now whether REL ever mentioned a gimbal range for the little motor, but I'm thinking a few degrees can't hurt.

Also I was wondering if 200 monopropellant is enough, considering how big this bird is and how quickly she burns through it. But I suppose the player can plan on adding more monopropellant tanks into the payload bay if the mission includes some tricky docking. So 200 probably is enough for most cases.

Edit again: Okay, my changes in addition to the mass balancing above were removing the lift factor from the payload bay (yes I know, I was kind of insistent that it have lift from the body... but this is stock aero, I was wrong, and the plane has too much lift) and reducing the amount of fuel and LOX. It had 10,000 oxygen, and 22,000 hydrogen balanced evenly between both tanks. I landed with 1200 LOX and something like 4000 hydrogen still in the tanks, so I think it can be reduced more.

Maybe a good goal for balancing the fuel load is to have the ability to deliver the orange tank into a 300km polar orbit, then return to a landing at KSC, with no more than, say, 250 LOX remaining? Might give a good pad above the minimum required, but prevent absurdities like flying Skylon to the Mun.

Edited December 5, 2014 by White Owl

[Climberfx]

Laboratory, to make it work for FAR here. Trying little adjustments...

Edited December 5, 2014 by Climberfx

[Guest]

Captain Kip,I installed firespitter.dll and the gamedata folder for Skylon C2,Im on MacOSX 10.10 Yosemite. as soon as i launched KSP,every single craft in SPH did not work anymore,KSP said it could not be loaded anymore,and the error was,locked or invalid parts missing,so I couldnt play skylon,nor my other crafts. Any solution?

[Climberfx]

I don't know if this is a solution, but firespitter.dll have a correct folder for it self.

Gamedata/firespitter/plugin.

I'm using with Yosemite and everything is fine.

[White Owl]

Okay, using the same setup as previously noted - balance changes, no lift on the payload bay, 10k oxygen, 22k hydrogen, and the orange tank payload - I took off from KSC, turned left to due north and flew into a 300km circular polar orbit. Left the payload there and returned to Kerbin. Got a little bit lost reentering over the pole in the dark (you've never been lost until you've been lost at mach 5), burned some more fuel and oxygen to correct, then landed on KSC runway 27 with 220 oxygen and 800 hydrogen still in the tanks.

Cpt. Kipard, flying that mission was some of the most fun I've had yet in KSP. This is a fantastic, beautiful spaceship.

I haven't tried a gliding, no power landing yet. I bet that'll be tough.

[CaptainKipard]

SlenderFan, did that help?

[Climberfx]

Having trouble with SOMA, it's center of trust is not pointed towards the center of mass close enough. I could notice that because i put 2.8x times it's current power to testing purpose, than i go back to editor and saw it is not pointing to COM (but above it, making ship pitch down on max power). Not on full tank and netter on empty tank. Because we have some diference on full and empty, i suggest it to be pointed to a medium way of this both COM (full/Empty). That way it will handle easily the diferences on the RW.

The same happens on rocket mode (not on jet mode, to my surprise). When i turn rocket mode on, besides that i need to put a 1/3 power do be controllable, if that rocket vector have a closer axis pointed to COM this too will help. On Atmosphere we can use the wings and body (Using FAR) to help keeping it pointed to right direction, but near space, and on space, only RW is useful (not using RCS for that, because is the way it should be, RCS for manoeuvres (docking etc)).

All this must be in a manner that this Center of Mass change just a little or nothing, besides the amount of cargo and or fuel i use to take off (in case of fuel, i'm always respecting the proporcional use of front and tail tanks, to be clear)

I hope this can help.

Edited December 5, 2014 by Climberfx

[Guest]

SlenderFan, did that help?

Trying now...

EDIT: No,I Didnt understand climberfx well though,I put it in the plugins folder And,did not work,so I installed the entire Firespitter plugin folder,with firespitter.dll in its plugin folder.

Trying 2nd time,Freezes at Almost there mark,Trying Now ATM

3rd time: Doesnt work Freezes at KipEng/parts/SkylonC2/SkylonOrbitalEngine/kipEngSkylonOrbitalEngine

Edited December 5, 2014 by Guest

[Climberfx]

SlenderFan.

When i installed Skylon, my machine got on the limit of mods. I have a lot of others here. So, on some game interactions, it crashes. This was because i have surpass the memory limit for the game (not for my computer, that i have a lot (20gb)). The way i handle this crashes when i reach some limit, is to remove others parts from all around, the ones that i never used, and i will never use too. That way, my game start working easily again.

In your case, i don't know how many mods you have, but i know it can lock on load if you are to above this limit. This way it will not load. The other motive to lock on load on some part, is because of some error on plugin or on a mod in particular. But we know for sure this is not the case.

Could be too that Firespitter have some conflict with one another mod that you have there. This way, you must check on Firespitter to solve that. Or on that other mod, but this we can't know.

So, i suggest, remove some parts and or mods...

Cheers!

Edited December 5, 2014 by Climberfx

[CaptainKipard]

WRT CoM and Thrust vector:

The only thing I can do is add gimballing to SOMA. I had to make some compromises when modelling things thing which meant the CoM will shift a bit when oxygen is used, and also people will want to put various payloads into the bay, so the CoM will move about anyway.

SlenderFan I don't know what's wrong if I don't know what your directory structure looks like. Did you install all the dependencies?

[Guest]

WRT CoM and Thrust vector:

The only thing I can do is add gimballing to SOMA. I had to make some compromises when modelling things thing which meant the CoM will shift a bit when oxygen is used, and also people will want to put various payloads into the bay, so the CoM will move about anyway.

SlenderFan I don't know what's wrong if I don't know what your directory structure looks like. Did you install all the dependencies?

Well,I Risked it without the 3rd dependence Nor The 2nd,Only used the ATM for replacement,so Im gonna try that..

Mods Currently Installed: Mechjeb2,Kerbquake,kerbaltek,Active Texture Management,Skylon C2 folder,Firespitter folder..

Question,could i have the link to The community resource pack though?

P.S to ClimberFX Im gonna reduce my memory usage now,im removing the mods that i to reduce and make skylon work..

Edited December 5, 2014 by Guest

[CaptainKipard]

Sorry I should have added the links

Community resource pack

Try installing the dependencies first, you might not need to remove any mods yet.

Edited December 5, 2014 by Cpt. Kipard

[Guest]

It works! Update: It works

[CaptainKipard]

Great. Your mod list is small; I think you can safely add more mods. You might not even need ATM yet. Also try LoadOnDemand, it saves memory in a different way that lets you view maximum resolution textures. You can only use one of those iirc. Links in OP and release post.

[Climberfx]

Yep, you can add a lot more.

Look what i use here, but some of these are not complete, because i tock some parts away...

Cpt. Kipard, LoadOnDemand is only for PC at the moment. Not for us, mac users. (Me and SlenderDan)

(but this is because i compromise resolution and texture quality...)

Mods list by Climberfx, on Flickr

Edited December 5, 2014 by Climberfx

[HafCoJoe]

It's GORGEOUS!!!!!!! Awesome!!!

[White Owl]

I've been testing the Skylon on a fresh install of KSP, with no mods other than the dependencies. Not even the engineer, so I still don't know how much total delta-V this thing has available!

Something weird happened when I put the plane together in the SPH instead of using the supplied craft file. Climbing through 20km altitude, the intake air suddenly disappeared from the resources panel. Rather than gradually decreasing, the gauge dropped instantly to zero. But the intakes were still collecting intake air like normal. At about 24km I manually switched modes and everything seemed normal for the rest of the flight. No idea what happened.