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

[blowfish]

I think FAR handles wings added asymmetrically fine. I got the FAR configs to the point where the only problem was pitch instability, which may be part of the design. The only solution I can think of is tricking FAR into thinking the wings are farther back than they are (easy to implement but not a solution I like very much).

[White Owl]

In my random experiments with changing the wing configuration but keeping the same fuselage and engines, I determined that (very technically speaking) something is hinky with the vertical stabilizer in FAR. The FAR config certainly looks right, but if you turn the airplane on its side in the SPH, the CoL marker is waaaay off in a very hinky place. That leads to a lot of directional stability issues. The plane sometimes flies like it doesn't even have a vert stab. Replace that stabilizer and rudder with procedural wing parts with identical dimensions, then the sideways CoL is where it belongs and the yaw issues are fixed.

Sorry I'm not more help. I wish I knew what was wrong with it.

[blowfish]

In my random experiments with changing the wing configuration but keeping the same fuselage and engines, I determined that (very technically speaking) something is hinky with the vertical stabilizer in FAR. The FAR config certainly looks right, but if you turn the airplane on its side in the SPH, the CoL marker is waaaay off in a very hinky place. That leads to a lot of directional stability issues. The plane sometimes flies like it doesn't even have a vert stab. Replace that stabilizer and rudder with procedural wing parts with identical dimensions, then the sideways CoL is where it belongs and the yaw issues are fixed.

Sorry I'm not more help. I wish I knew what was wrong with it.

Yeah, I noticed the weirdness with the CoL marker too. I suppose I never saw it in flight because the plane always did a backflip before directional stability became an issue.

[CaptainKipard]

Re: Your rudder troubles, that's something that might have a simple solution. I can definitely make the vertical stabiliser surface-attachable because that part is not load-bearing. The wings will need to stay the way they are though.

Also many thanks for testing this in both aero models. I'm really happy that you can land safely.

Edited March 19, 2015 by Cpt. Kipard

[sashan]

I guess your plane is rolling over? I think FAR assumes that the ring is going from model origin till the "length" coordinate in the right direction.

You may try different parameters for each wing. Maybe negative wing span for the left wing?

You can also try to reorient them in blender. This way, you'll have to turn it over in SPH.

Just a couple of my suggestions.

I want to rescale it for RSS. It has no IVAs, so that should be fairly trivial task.

[sashan]

One question. Are the units of the resources liters? I am playing with realism overhaul and with realfuels. This mean I can make a config for that.

[CaptainKipard]

One question. Are the units of the resources liters? I am playing with realism overhaul and with realfuels. This mean I can make a config for that.

I don't even know. Kerbal resources are a mess.

[blowfish]

Re: Your rudder troubles, that's something that might have a simple solution. I can definitely make the vertical stabiliser surface-attachable because that part is not load-bearing. The wings will need to stay the way they are though.

I'm curious as to why the rudder doesn't work when all the other wings do. I don't think it's a question of surface vs node attachment. Could possibly try rotating the whole model 90 deg so that it has the same alignment as the other wings...

[sashan]

Ok, I've tested the Skylon with NEAR. First of all, you deserve a big thumbs up. And a cookie.

Using FAR config found a few pages ago, it flies. The center of mass is ridiculously moved to the back. It should be in the center of cargo bay. I've used old hack of wing panel hidden inside of the fuselage to test the vehicle. I am now fixing the mass distribution via modulemanager, that's a tedious process. For example, you have OMS engine weighing almost 2 tonnes, and it is one of the smallest parts.

On a side note, NEAR is similar to FAR except that it models the air as uncompressible, meaning no speed of sound-related effects. Also, it doesn't take part overlapping, wing part interaction and similar effects into account. And no aerodynamical failures.

Also, the RCS consumption is somewhat crazy. It is drawn with 11 units per second. I've enabled RCS just after sabre cutoff, and run out of monoprop before apoapsis.

Oh, and RCS thrusters for rotating would be located in the extremities of the vehicle. This can lower RCS propellant consumption for rotation two times. Well, nose is a hot part, but no reason not to have them in the tail, and another set for roll - on the engines.

Rudder indeed doesn't work. I've used a substitute made out of 4 pieces of Porkjet's wings. The original project is planned to have all-moving tailfin, not just a conventional rudder.

While using latest firespitter on my RO install, the nose wheels started rotating around roll, not pitch axis. It looked really weird.

Top speed with NEAR was around 800m/s, that's 2 times lower than the real one has. The altitude was 25km in Earth atmosphere - that's around 16km in Kerbin's. This may be due to a fact that FAR config nerfs the engines by a factor of 1.3. I'll test it further.

Another question: Which size have you used? Which rescale factor do I need to put it up to a size of a real thing? This deserves an RO config.

Edited March 19, 2015 by sashan

[CaptainKipard]

I'm curious as to why the rudder doesn't work when all the other wings do. I don't think it's a question of surface vs node attachment. Could possibly try rotating the whole model 90 deg so that it has the same alignment as the other wings...

The rudder is oriented in unity exactly the same as one of the wings, because that's all it is afa the game is concerned.

Ok, I've tested the Skylon with NEAR. First of all, you deserve a big thumbs up. And a cookie.

Using FAR config found a few pages ago, it flies. The center of mass is ridiculously moved to the back. It should be in the center of cargo bay. I've used old hack of wing panel hidden inside of the fuselage to test the vehicle. I am now fixing the mass distribution via modulemanager, that's a tedious process. For example, you have OMS engine weighing almost 2 tonnes, and it is one of the smallest parts.

On a side note, NEAR is similar to FAR except that it models the air as uncompressible, meaning no speed of sound-related effects. Also, it doesn't take part overlapping, wing part interaction and similar effects into account. And no aerodynamical failures.

Also, the RCS consumption is somewhat crazy. It is drawn with 11 units per second. I've enabled RCS just after sabre cutoff, and run out of monoprop before apoapsis.

Oh, and RCS thrusters for rotating would be located in the extremities of the vehicle. This can lower RCS propellant consumption for rotation two times. Well, nose is a hot part, but no reason not to have them in the tail, and another set for roll - on the engines.

Rudder indeed doesn't work. I've used a substitute made out of 4 pieces of Porkjet's wings. The original project is planned to have all-moving tailfin, not just a conventional rudder.

While using latest firespitter on my RO install, the nose wheels started rotating around roll, not pitch axis. It looked really weird.

Top speed with NEAR was around 800m/s, that's 2 times lower than the real one has. The altitude was 25km in Earth atmosphere - that's around 16km in Kerbin's. This may be due to a fact that FAR config nerfs the engines by a factor of 1.3. I'll test it further.

Thanks but all of this is very likely to become moot when the new aero model is released.

Another question: Which size have you used? Which rescale factor do I need to put it up to a size of a real thing? This deserves an RO config.

The diameter of the ends of the cargo bay is 5m. You can look up the actual diameter of the plane yourself if you want to scale it up to real size. It wont fit any parts though because I created the cuts exactly where the diameters are of standard sizes.

[sashan]

What's happening with my nose landing gear? The wheel rotates, but on the wrong axis. And the whole gear is shifted.

In this screenshot, I am using FAR config. It only changes mass and drag of the gear.

Edited March 21, 2015 by sashan

[CaptainKipard]

What's happening with my nose landing gear? The wheel rotates, but on the wrong axis. And the whole gear is shifted.

In this screenshot, I am using FAR config. It only changes mass and drag of the gear.

http://i.imgur.com/vRoTpEN.png

Is anyone else having this problem as well?

Did you ask Snjo about it?

[sashan]

No, I'm asking the whole community. Should I PM Snjo?

Still I was able to takeoff. Just like that Jet Blue airbus landing.

By the way, made it to orbit with NEAR. I've got center of mass exactly at the cargo bay center, and it immediately flew perfectly. Cargo bay is put there for a reason on real one. Got over 2k dV left. Engines are overpowered as well - over 2x TWR at start with airbreathers, 9.0 TWR on burnout.

EDIT: Can't get imgur to work. Here's the direct link.

http://imgur.com/a/yxtO8#2

Edited March 21, 2015 by sashan

[CaptainKipard]

You should ask him about it obviously. I didn't change anything.

[White Owl]

The original project is planned to have all-moving tailfin, not just a conventional rudder.

Wait, really? Got a source for that? I don't think that detail was in the available manual.

[CaptainKipard]

Wait, really? Got a source for that? I don't think that detail was in the available manual.

The 3d visualisations show that. I've already corrected this but haven't uploaded it yet.

[Climberfx]

A long time i don't play with Skylon, and KSP too.

So, is any chance or anyone already test it with new FAR update?

I read about the wait for 1.0, i keeping ask my self if that aero update will deprecate FAR, or turn it to not necessary anymore.

Or will be just a little Aero upgrade, but not as realistic as FAR.

[blowfish]

I read about the wait for 1.0, i keeping ask my self if that aero update will deprecate FAR, or turn it to not necessary anymore.

Or will be just a little Aero upgrade, but not as realistic as FAR.

Based on the information we have, the 1.0 aero update will be nowhere near as detailed or realistic as FAR. Furthermore the devs have committed to maintaining moddability, so FAR will continue.

[sashan]

I've made a config, based on the one posted a while ago in this thread. However it still flies like a brick out of catapult. All kinds of oscillations and instabilities, despite COM and COL being in correct places with angles of attack and sideslip below 5 or 10 degrees. Front canards need to turn quicker.

Also, due to the nature of available automated control systems it can only be flown manually.

[Climberfx]

Based on the information we have, the 1.0 aero update will be nowhere near as detailed or realistic as FAR. Furthermore the devs have committed to maintaining moddability, so FAR will continue.

That is a wonderful news!

Thank you Blowfish!

[CaptainKipard]

I'm not promising official FAR implementation.

[Mecripp]

Any chance on a Boeing X-37 it would be like a baby skylon for them smaller jobs ?

[Mecripp]

Something is bugging my skylon it shows alittle LiquidFuel and Oxidizer on the skylon but, I can't found them in any of the cfgs maybe a bug with ModularFuelTanks but when goto ClosedCycle it still want to burn Oxidizer and not LiquidOxygen so you get a flame out anyone else have this problem ?

[CaptainKipard]

Any chance on a Boeing X-37 it would be like a baby skylon for them smaller jobs ?

I have no plans to do that.

Something is bugging my skylon it shows alittle LiquidFuel and Oxidizer on the skylon but, I can't found them in any of the cfgs maybe a bug with ModularFuelTanks but when goto ClosedCycle it still want to burn Oxidizer and not LiquidOxygen so you get a flame out anyone else have this problem ?

Given that neither I nor Squad updated anything since the last time I played with this, I'm concluding that it's a problem with another mod. I can't help, sorry.

[Mecripp]

Found it was Advanced Jet Engine that not playing nice with the skylon.