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General FreeSpace => FreeSpace Discussion => Topic started by: Stealth on August 18, 2002, 09:59:58 pm

Title: nebula lines
Post by: Stealth on August 18, 2002, 09:59:58 pm

i'm a n00b to FS2, so don't start flaming, but i've noticed in some missions (nebula missions) there are 'trails' coming from the back of ships as they're flying, like two ribbons, one on each side.

i know this has a name, just can't think of it, and what's the "story" behind them?  why only in nebulas?

don't some fighter planes nowadays generate them?  something with oxygen mixing or something

Title: nebula lines
Post by: Anaz on August 18, 2002, 10:05:47 pm

its the turbulence off of the edges of turbulence generating things. It also makes targets easier to track in the neb. Something about the air being so turbulent, that it does something funny and becomes visible.

I don't relly know the physics behind it, but I do know that it is caused by turbulence...

Title: nebula lines
Post by: CP5670 on August 19, 2002, 12:05:27 am

Since the FS2 nebulas are extremely dense, the displacement of the gas where the fighter used to be (as it moves) might create a trail-like effect, but the trails would not be so well-defined and concentrated. Probably was just done to look nice. ;)

Title: nebula lines
Post by: ShadowWolf_IH on August 19, 2002, 12:21:37 am

those are called wingtip vortices......and they can be quite deadly to following craft in the real world.  They caused a chase plane to run into the XB-70 prototype, destroying both aircraft.

Title: nebula lines
Post by: vadar_1 on August 19, 2002, 01:01:29 am

Quote

Originally posted by CP5670
Since the FS2 nebulas are extremely dense, the displacement of the gas where the fighter used to be (as it moves) might create a trail-like effect, but the trails would not be so well-defined and concentrated. Probably was just done to look nice. ;)

I think it was either
1) lack of engine support for actual displacement effects, or
2) what shadow said...

Quote

Originally posted by ShadowWolf_IH
those are called wingtip vortices......and they can be quite deadly to following craft in the real world.  They caused a chase plane to run into the XB-70 prototype, destroying both aircraft.

I think this is what they were actually trying to do, but it shouldn't be the same in nebulas.

Title: nebula lines
Post by: Bobboau on August 19, 2002, 01:13:52 am

there called contrails
in the game at least

Title: nebula lines
Post by: Knight Templar on August 19, 2002, 02:14:07 am

Stealth..... a n00b :eek: ..... no way jose

i always though those things were cool.. don't they go away if you slow under a certain speed in the game though?

Title: nebula lines
Post by: ShadowWolf_IH on August 19, 2002, 05:17:27 am

contrails differ from this in real life.  they are created by engine exhaust.  That big long line of white behind a jet passing overhead.  Certain atmospheric conditions allow this to be very long......a fighter pilot's enemy.....and certain conditions will make this shorter......a fighter pilot's friend.

Title: nebula lines
Post by: Stealth on August 19, 2002, 10:52:40 am

Quote

Originally posted by Knight Templar
Stealth..... a n00b :eek: ..... no way jose

at FS2 information, like ship names and classes...

i'd 0wn you and anyone else at playing FS1 or 2, :D

Title: nebula lines
Post by: Stealth on August 19, 2002, 10:56:00 am

why are the 'tails' so bad?  why are they so dangerous?  they're only a gas, right?

Title: nebula lines
Post by: ShadowWolf_IH on August 19, 2002, 11:12:57 am

those wingtip vortices are swirling masses of air.  They can cause engine disruption in jets, and when the control surface of an aircraft flaps, alierons. rudders, mobile canards) hits these, it is normally enough to take the control stick out the hand of the pilot.  think of how much pressure that would take....and think about the fact that to override the autopilot it only takes 25 lbs of pressure.  Couple that with the buffetting of the vortice itself making each control surface do something different, and your plane is one big expensive missile. Also, if you have that kind of pressure pushing down on one wing, and you have plenty of lift under the other, you are going into an uncontrolled barrell roll.  The plane will probably porpoise (nose up, then nose down, then nose up again....etc etc) as the pilot attempts to regain control.  This is a bad thing.

here's an example.......when you pass your hand through water....slicing like a karate chop (for lack of a better term), as oposed to an open hand slap, it flows through easily, but the water fills in the place where your hand was from both above and below, and you can almost see it filling in.  Now when you get a plane doing that through the air a supersonic speeds, the air does the same thing, but in a much more violent manner.  The plane is creating a near vaccuum, and the air is rushing to fill it.  those different wind currents will hit one another, and swirl violently about.  that is why they are dangerous.

the problem increases ten fold when we look at the inherent instability of a forward swept wing aircraft (x-29, Switchblade), and about 5 fold with variable geometry wing aircraft (f-111, f-14, Switchblade), or with a machine with mobile canards (f-15E, f-16 ATFI).

so far the only way to even combat this problem is through the use of vector nozzled engines and reaction control valves to replace the aforementioned control surfaces.  Some of the newer designs on the shelf are using them, the Switchblade, uses reaction control valves to a certain degree, but she isn't in production, more's the pity.  

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Title: nebula lines
Post by: Galemp on August 19, 2002, 08:57:50 pm

Hmmm. Well, anyway, they look cool and they're a personal source of pride, as I know I've finished a model when I put the contrails in the table.

Title: nebula lines
Post by: StarGunner on August 20, 2002, 02:15:06 pm

Quote

Originally posted by GalacticEmperor
Hmmm. Well, anyway, they look cool and they're a personal source of pride, as I know I've finished a model when I put the contrails in the table.

You and me both I hate it when the is no contrails on ships if I find em I pout em on too. makes it feel more complete.:sigh: