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

[EatVacuum]

Skylon doesn't need big wings, because it's a lifting body design. Essentially, the whole body functions as a giant wing. Unfortunately, KSP doesn't simulate that.

To quote what someone earlier said about my speculation on where to put the thrusters "That sounds suspiciously like an opinion...". I haven't come across anything stating that the fuselage is a lifting body, but if it is, we can do it. On the other hand, I did come across something that indicates that Skylon has a pretty high takeoff speed in this forum; "With a takeoff speed of M0,5 (over 250KIAS) and rocket engine like thrust, it should climb... almost like a rocket".

If this is correct, at Mach 0.5 (actually 330 KIAS, knots indicated airspeed, which is about 350mph) Skylon would be going more than twice as fast as a typical airliner, or almost twice as fast as a typically combat loaded F16 at takeoff. That will go a long way to making up for the small wings. But I haven't found anything official that confirms the forum quote is correct. So if anyone can prove either of these statements, we'd appreciate you providing the source.

In the meantime, in case we do need to go down that road...

Can't I just add deflectionLiftCoeff to every part?

It's a simple change to the config file, I can probably make any KSP part into a lifting body. As proof I offer the amazing lift-cubes; all the lift of a delta wing, but much more space efficient. I hope to market them to any Kerbal nation that uses aircraft carriers or is plagued by narrow hangar doors...

And in case anyone is doubting the lift is provided by the modified QBE probe cores, you will note in the SPH shot below the Centre of Lift is clearly on the cubes. The flaps are needed for flight control and the 1x1m structural panels are only there because I needed something to attach flaps to, they wouldn't go directly on the cubes.

[CaptainKipard]

The manual says the take-off speed is "close to Mach 0.5"

[EatVacuum]

Now that the forum is back, I have a few thoughts about the parts list and earlier comments;

You forgot the control core. Actually it's even more complicated than that. I'm working on the mid section right now and it's proving to be deceptively difficult. It looks simple and the overall shapes kind of are, but I have to constantly keep in mind that I'm going to break things up into sections later. It's a bit of a balancing act. e.g. the wing base extends beyond the ends of the cargo bay in both directions. Now in order to make the wing mesh look smooth I can't just slice the whole thing exactly where the cargo bay ends. I'll have to cut a bit further. Luckily the Skylon cross sections show that's where the oxidiser tanks are so I'm thinking the cargo bay part should double as an oxidiser tank. And there's still the issue of the heading/prograde discrepancy. I have one idea for that but it's a bit of a hack. I was hoping there's a more elegant solution by using something in the cfg. Could you look into that too?

Here's how I see it.

-Nose/Core 1

-Core 2

-Forward Monopropellant tank

-Forward Hydrogen tank

-Cargo Bay/Oxidiser tank

-Aft Hydrogen tank

-Aft Monopropellant tank

-OMS

-Vertical stabiliser

-Rudder

-Left wing

-Left aileron

-Left intake

-Left "precooler" (Just a structural part)

-Left engine

-Right wing

-Right aileron

-Right intake

-Right "precooler" (Just a structural part)

-Right engine

-Canard

-Nose gear

-Left rear gear

-Right rear gear

-One or more RCS thrusters (depending on how they will be placed)

I think this list is good, but a couple of thoughts. Some people will want this as a kit to fly a realistic Skylon, but it would be a bonus if the parts were also useful for building other craft. You're making a start on that by going with one of the existing part diameters rather than going with the exact 64% or 50% resizing. I think we should continue this a bit further - I'd like to keep the fuel and oxidizer in the same tank/part, but that said, it doesn't change where you cut the parts. How much fuel/oxidizer goes into a part is controlled by the config file, not the actual volume of the part. We also only need to reach 40% or so of real world orbital velocity to get into Kerbin orbit, so having a bit less fuel than we could won't likely be a problem and should even leave a reserve for powered landings.

Another thought, related to the previous - if you cut the nose cones etc. at points where the diameters match existing diameters then it would make the parts more reusable, for instance maybe parts like the nose core can be cut off where it reaches the 1.25m or 2.5m diameter point, even if it is a bit off from the logical divisions based on function. Same thing for the orbital maneouvering system, RCS and so on. I was going to suggest splitting the engine into two rather than three, but on second thought, doing it does allow someone to use the intake and engine without having to stick to the "banana" shaped overall shape, so go with that. It would also make it easier for people to model the Lapcat, since the Scimitar engine doesn't seem to have the banana curve. With the forum down, this suggestion may have arrived too late, but if not, give it some consideration. As always though, this is largely your project, so the modelling choices are best left to the modeller.

Since Skylon is meant to be capable of docking, then simple attitude control is not enough. Like I said before I think adding some seperate RCS parts is the best way to go. I've seen Skylon animations showing propellant being ejected from both the nose and the tail but the docking animation doesn't show anything.)

Yep, looked at the video, that and Figure 11 "Suborbital deployment..." in the Skylon user manual definitely confirm the positioning of the pitch/yaw thrusters right at the bow and stern. That leaves the roll control up for question, but making separate attachable RCS for the wings and including roll thrust in the bow and stern would allow for both options.

I'm pretty sure adding a custom resource is relatively easy. There's some info about it in the tutorial thread, but if you have a problem you can always post a question.

I'll look at that for sure. Depending on when .22 comes out, we may not have to do that. If it should happen that different fuel technologies are part of the R&D tree (and I think that would be a realistic option to allow for developing more efficient engines), then we may have more options than just going with generic liquid fuel or making a custom hydrogen (Krydrogen?) resource. If not, then I should provide both options - hydrogen-based fuel tanks and generic fuel.

Now a last question - what colour should we go with? The black paint scheme shown in the RE videos is appealing, but should we consider going with a paint scheme that better goes the existing common colors? I expect that once/if Skylon becomes a reality, it would sport different colors for the companies that fly it, just like airliners, since it looks like they are expecting to sell them commercially. So we don't have to be tied to what Reaction Engines is using. Any thoughts?

Edited September 24, 2013 by EatVacuum

[CaptainKipard]

it would be a bonus if the parts were also useful for building other craft ..... if you cut the nose cones etc. at points where the diameters match existing diameters then it would make the parts more reusable, for instance maybe parts like the nose core can be cut off where it reaches the 1.25m or 2.5m diameter point, even if it is a bit off from the logical divisions based on function.

I'm way ahead of you. One of the first things I did was create edge loops where the cross sections have standard diameters.

... I'd like to keep the fuel and oxidizer in the same tank/part ...

If you think that's best.... I'm just curious why you think that's the best way to go.

... doing it does allow someone to use the intake and engine without having to stick to the "banana" shaped overall shape, so go with that. It would also make it easier for people to model the Lapcat, since the Scimitar engine doesn't seem to have the banana curve.

That seems reasonable. I'll have to check the Scimitars dimensions, but if they're similar to the Sabre then I'll try to make the intake and engine compatible with both precoolers.

Actually it just occurred to me, that the Scimitar intake would not be the same as for a Sabre because it doesn't need to be closed. I'll need to look into it.

With the forum down, this suggestion may have arrived too late...

No, I was playing Skyrim during the server change. Now that we're back up I'll get back to modelling.

As always though, this is largely your project ...

Please, no false modesty. I really hate it.

Krydrogen?

I understand people love to put "K" in front of everything but I don't think that's really necessary. Hydrogen is the same wherever you go, and the only reason the name "Kethane" works is because Kethane is a fantasy resource. Of course if the devs decide to implement a lightweight fuel similar to hydrogen and name if something then we can go with that.

Now a last question - what colour should we go with? The black paint scheme shown in the RE videos is appealing, but should we consider going with a paint scheme that better goes the existing common colors? I expect that once/if Skylon becomes a reality, it would sport different colors for the companies that fly it, just like airliners, since it looks like they are expecting to sell them commercially. So we don't have to be tied to what Reaction Engines is using. Any thoughts?

Absolutely. Firstly in addition to black, in recent weeks a new render has appeared showing Skylon sporting a more traditional Shuttle-type black and white colour scheme. Secondly I'll want to make some stockalike textures too. Thirdly I'm thinking of implementing the flag texture functionality into the vertical stabiliser, which would allow players to put unique flags on it for every plane they launch. I'll have to think about the best way to do that.

[NoMrBond]

I understand people love to put "K" in front of everything but I don't think that's really necessary. Hydrogen is the same wherever you go, and the only reason the name "Kethane" works is because Kethane is a fantasy resource. Of course if the devs decide to implement a lightweight fuel similar to hydrogen and name if something then we can go with that.

In the resource flow diagrams that have been posted so far water could be split into Propellium + Oxium, which I guess makes Propellium = Hydrogen

[EatVacuum]

If you think that's best.... I'm just curious why you think that's the best way to go.

I'm just thinking that complete sections with oxidizer and (whichever) fuel we go with would be more reusable than giving them a tank with fuel only, especially if the oxidizer is in the cargo bay section. That was why I was also thinking of providing liquid fuel plus oxidizer versions even if I do figure out the hydrogen resource thing - more reusability.

Also - Design conversation in the forum is good because it gives us useful feedback from interested players. But I'm thinking we should have a contact channel other than going through the forum, both in case it goes down again and to allow us to exchange our WIP files at some point. I'll need parts to be able to validate the configs, and you'll need the vice versa. And if we end up having to get someone else to import your parts into Unity, they will as well. Speaking of, I did spend time trying to get a sample part into Unity and there is some learning curve, I haven't gotten it right yet, I guess it's more tutorial watching for me.

Edited September 25, 2013 by EatVacuum

[Requiem762]

Any updates so far?

[CaptainKipard]

I'm trying to figure out how animations work. I need to decide how to proceed with modelling the landing gear depending on what resources are available to me.

[EatVacuum]

Any updates so far?

I've cobbled together a "good enough" 1.25m Sabre engine model to play with while Cpt. Kipard works on the real models; no intake animation on close/open and standard rocket fx. And with that I have been working on the Sabre engine; getting a better understanding of config files through experimentation and rewrites, fine tuning the performance to get it to as realistic a flight profile as possible, and lots of test flights of course.

Here's my test plane and engines - I should have had the logo run along the side of the engine rather than around the circumference. I'm not expecting this to be the final look (that is in the modeller's hands) but I needed to differentiate my test Sabre from the one in the B9 pack which I've also been test flying for comparison.

The widening of the engine from front to rear is a pain for putting onto planes built on 1.25m fuselage and the stock landing gear - the things tend to scrape the runway on take off. This won't be a problem with Skylon though as the fuselage is proportionately much bigger because of the low density of LH2 fuel and resultant high volume needed. But it could be for people who want to reuse the part.

Right now I'm still using the LACE model (Liquid Air Cycle Engine - i.e. using a modded intake to produce oxidizer from intake air and an engine that really only works in rocket mode) for testing. But I've been looking at the creative commons license B9 is packaged with and while I'd like to get a confirmation from Careo or Bac9 (and if either of you read this, let me know if you mind please), I think that as long as we give due credit we can use the Exurgent Engineering .dll to get the true open/closed cycle mechanism. If not, I guess it's a crash course in C# programming for me.

And, another idea I've been having - after doing all the research on Sabre, LACE,turborockets, scramjets, ramjets, ramrockets, air augmented solid fuel boosters and so on for this project, I have a hankering to make an add-on pack with all of those variations of engines. I've had little luck with Eve landers so far and air augmented rockets would work great on Eve. You'd need oxidizer but making use of that atmosphere as additional working mass will still result in higher ISP than conventional rockets. But that can wait until this project is done.

[Requiem762]

So is this mod dead?

[sal_vager]

Last post 8th October 2013, so probably not

[EatVacuum]

So is this mod dead?

Deadish I'd say. I wanted to build the Sabre engine for my own purposes, but I didn't have much recent modelling experience. CaptKipard wanted to build the whole Skylon space plane so we partnered up. But he seems to have dropped off the forum for a bit. I'm hoping he'll resurface at some point, but in the meantime I'm waiting before abandoning this.

[NoMrBond]

Maybe the native support for multiple fuel type/switching engines (such as the SABRE) coming in 0.23 will bring it back to life

/cueFrankensteinLightning

[CaptainKipard]

Look. I know it's been weeks but I haven't abandoned this, I'm still working on it. The problems I have are:

a) Skylon blueprints are non-existent in the public domain. I'm having to effectively design parts of this plane from scratch, e.g. Landing gear configuration, precise angles of various part of geometry, etc. If I had proper blueprints and schematics I would have probably been texturing it by now.

Modding documentation for KSP is woefully inadequate and I've never used Unity before. The only modding experience I have is modelling and compiling art assets for Half-Life 2.

Now I'm kind of close to finishing what I think is the most problematic part of this mod and that's the landing gear. I had to use the Concorde for reference. I know I'll have problems with it because there's very little info on how to set this up and what info there is is rather vague. I'll send a message to the guys who are making the mini shuttle. Maybe one of them can write a proper tutorial for it.

[EatVacuum]

Glad to hear you're still alive. Looking forward to seeing the final product models.

And referring to an earlier post, it does look like the update on .23 work in last week's Devnote diaries both resolves the question of whether we'd need to use Exurgent's engine .dll (or that I would have to learn C#);

Chad (C7): ... I’ve also added multi-mode engines. These will allow for engines that are air-breathing and transition to rockets, or any combination thereof. They’ll each be able to have their own FX, engine performance stats and propellants.

Which is good news, but it pretty much shrinks my work on the project to almost nothing. But, I'll still do the configs etc. if you need it, and I'll happily flight test.

[CaptainKipard]

Here's some progress. It's a nose gear obviously. It's all designed to animate and be neatly hidden away inside the nose. Whether or not we'll be able to get it into unity is another matter. I've glanced at the Mini Shuttle thread and it looks like even that guy is having problems with unity implementation.

In addition to the nose gear I've also unwrapped most of the model.

-- Image Deleted --

Edited July 24, 2014 by Cpt. Kipard

[Naten]

HAI! I heer to join yer teem!!!11

Like I said, can I handle an A2 Lapcat, please?

I'm an REL enthusiast. I'd love to work with people who want to do something like this.

So, whaddya say? :3

[CaptainKipard]

I'm not saying this to be offensive but objectively I think you should start with something simpler. It would give you a chance to develop your skills without stressing about too many things. Let me tell you, a whole plane is no cakewalk.

One of the side projects for Skylon is the Personnel & Logistics Module. I was hoping to start on it right after finishing the plane itself, but if you're up for it then that would be a big help. You can (and please do) google schematics and dimensions for it and keep everything proportional. If you're having problems I can point you in the right direction. Only do the model for now. Don't unwrap or texture it, because I'll need to import your model into my skylon model and correct things so it all fits.

I hope you consider helping with this, but if you don't want to then you are absolutely free to make a Lapcat, but then that would be your own project because we only talked about the Lapcat in passing. We might or might not do it. In any case, we need to finish the Skylon first.

[Naten]

Awww. D-... D'awww. Aw-AAAAWwwwwww. Awwwwwwwwwwwwww.

:c

[Naten]

Is this good?

[CaptainKipard]

It's a good start but it looks like you rushed a bit, because it's missing some things and some details aren't proportional.

[Naten]

Well, it's just a start, of course. I'm never good at scaling, though, and I'm sorry for that.

[hieywiey]

I LOVE this new one, the tires got my attention when I first looked at it:P

[CaptainKipard]

I LOVE this new one, the tires got my attention when I first looked at it:P

Why the tires?

[hieywiey]

I don't know, maybe it's the attention to detail.