Vessel Finishing what stevecast Started

jedidia

shoemaker without legs
Addon Developer
Joined
Mar 19, 2008
Messages
10,830
Reaction score
2,088
Points
203
Location
between the planets
SC3 is pretty much dead in Orbiter 2016, though... It's really painful to use. VesselBuilder is a more compatible generic framework.
 

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
0242.jpg0246.jpg0247.jpg0250.jpg0251.jpg0252.jpg
0248.jpg

repaired holes, normals, mesh rework (it's still silly big! but I didn't want to redo the whole thing), redone UV's, new tex., +++
I could make a SC4 version with less features.

Mass: 8.4 million metric tons, so how much fuel, and what thrust and ISP?- with fantasy vessels there's not much to go on!

P.S. @AllOrbiterModders a big shout out to "the guy that made the Blender Orbiter Plugin". I used to work with 3DSMax and the torture to get anything even halfway into Orbiter! Now one click and open orbiter! it's that easy, it does everything. IMO the only way to go. Using Blender 3.1.2 with Orbiter Mesh Tools 2.0.12 from Blake Christensen.

EDIT: replaced screenshots, forgot to Apply all transforms!?!
 
Last edited:

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
Mass: 8.4 million metric tons, so how much fuel, and what thrust and ISP?- with fantasy vessels there's not much to go on!

I could look into the Babylon 5 Wars rules tomorrow. For example, we could scale it relative to other vessels, like the Omega destroyer.

The maximum acceleration there was depending on the available thrusters and the engine power (including overthrust by putting more energy into the engine - the game was very complex and challenging, but also fun)
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
Sooo, now, for the beginning....

1667064689846.png

For reference, thats how the record sheet for the small basic Hyperion (Theta model) looks like in Babylon 5 Wars.

A lot of thrusters and stuff, thats really hard to translate into Orbiter and most of it related to the damage model, so we can ignore it.

We have three thrusters in the rear, which together offer a maximum of 7 thrust points without overthrusting. That is just the safe limit. You always had been able to shut down weapons and other systems to get more energy and turn it into additional thrust, that can be used to buy more thrust. The engine in the center has an efficiency rating of 4/1, which means, it needs 4 points of additional energy for producing one point of thrust more, and generally produced 7 points of thrust. The maximum power you could get by shutting everything down except the engine is 50, which means 12 points of extra thrust possible, to a maximum of 19.

Now, this isn't the acceleration, thats more like the thrust force rating... there was another conversion since some ships turned better than others for the same amount of thrust, others accelerated or decelerated better, etc.... a lot of options.

The Hyperion had a pretty average acceleration/decelleration cost of 3, which means changing the velocity by one, you need 3 points of thrust per turn. Which means, using all overthrusting possible, the Hyperion would be able to change its speed in one turn by 6 points, which is proportional to the maximum newtonian acceleration possible in Orbiter.

The rest now is defining, what one point of acceleration actually means in Orbiter. In Battletech, its fairly easy, there the definition was 1 point of acceleration = 0.5g. Here things had been left undefined, since there never was any physical definition at all: Neither the duration of a turn, nor the size of a hex field was ever defined. But that also means: Full creative freedom.

If you want things to be agile and fast, make one point of acceleration worth 10 m/s². Then the usual acceleration of 2 of an Hyperion would be equal to about 20 m/s² acceleration. If you want things to be less insane, if fighters and more advanced ships are involved, use 5 m/s², then the ship can still accelerate at about 1g, but get out of the way at 3g, if needed.

For comparison: The more advanced Omega destroyer has 60 points of extra power available when shutting everything down, has a more efficient engine and is capable of turning this into 20 points of extra thrust, to a total of 28. This means, it can get a maximum acceleration of 9 or 50% more than the Hyperion (At "Dreifach wahnsinnige voraus" / "Triple insane ahead", as German submariners would name this mode)

And if you want to compare this to the Sharlin.... don't. You'll think EarthForce vessels are as fast and agile as a pregnant yak.

If you want to get access to the record sheets of all vessels in B5Wars, because your CDROM from the Ships of the Fleet supplement (that you sure all are owning, right) has gone missing, look here:

 
Last edited:

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
Thanks Urwumpe
Just to note: It has an additional 4 thrusters amid ship (for crazy cornering maybe?).
So maybe max 3g fully loaded? I quess it doesn't really matter, IIRC most previous fantasy vessel addons just had generic excessive thrust and ISP. But it would be nice to have some relative correlation between canon, realistic and other vessels, did Stevecast have a system?
Babylon5 tech, what do they use for energy, fuel? Can one estimate approximate mass percentage for fuel? and respective ISP.
-Reminds me of playing Traveler looong ago:)
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
Thanks Urwumpe
Just to note: It has an additional 4 thrusters amid ship (for crazy cornering maybe?).

Exactly. For flying a turn, you would have used these thrusters together with some forward or aft thrusters for giving the ship some weird "aircraft like" behaviour. These thrusters would also be used for lateral slide maneuvers.

Of course, it doesn't really make sense in space combat to act like that, thats tabletop simplification to only use a velocity scalar. There was also a custom rule around to support 2D velocity vectors and more use of the "pivot" maneuver to turn the vehicle into the necessary direction.

Again, B5Wars provides a useful way to get the balance and characteristsics between the spacecraft right, but can not tell you how to translate these spacecraft into Orbiter.

According to the descriptions of the spacecraft, they all used an limited amount of an reaction mass, except the more advanced spacecraft with Gravitic Drive system, like the Minbari have. Nothing is said about the fuel used to produce energy. Most spacecraft of the Earth Alliance had been barely able to travel through the whole solar system and return, also the existence of an artificial gravity section on some newer Earth Alliance ships suggests, that the spacecraft and crew can spend in unpowered flight with these, while older spacecraft had been limited by reaction mass and crew endurance to travel longer distances.

I would say, you can use some creative freedom there, but I would use the following thinking there:

  1. Most spacecraft have ~20%-25% propellant mass.
  2. If the spacecraft has a gravitic drive system (Minbari, Brakiri, Ancients), the spacecraft only has ~5% propellant for representing the energy source.
  3. If the spacecraft has an artificial gravity section (like the Omega) I would give it about 5% less propellant, since it can spend more time in unpowered flight.
  4. If the spacecraft is longer ranged (like the Explorer), I would give it more fuel, up to 40%.
I would define the mission and thus the specific impulse as such:

An average spacecraft has to be able to travel 2x15 AU at 10 m/s². That means ~2 x 170,000 seconds of burntime at 1g (2 x 48 hours) and thus a total DV of about 3400 km/s. That leads to an specific impulse of 11818 km/s, maybe rounding up to 12000 km/s.
 

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
Exactly. For flying a turn...
OK! I thought I was making a joke:LOL:
Your propellant mass and ISP sound reasonable, I can work with that, I'll plug'em in and see how it "feels".
 

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
I thought the excessively large engine bells had more to do with testosterone than anything else but maybe not:
To push 8,400,000,000. kg up to 3g the beast needs a whopping 250,000,000,000. N thrust! That blows the scale for anything (at least at Atomic Rockets), even antimatter.
Apparently:
Modern Heavy Cruisers are powered by three fusion reactors, with a energy output of 8.94*1021 joule, and an time average power output of approximately 191.7 Terawatts over eighteen months or 4,929 Terawatts under combat conditions, time averaged over three weeks. Ships propulsion is provided by three BB9K ion/particle engines...
-Source: Celestia

If there is interst I can research something more realistic for ion/ particle engines.

So with 2,100,000,000. kg fuel, 25% total mass, and an ISP 12,000,000.m/s I get a DV 3,400,000,000. m/s (3,400Mm/s(^10 your estimate?)) and BurnTime ~101, 000. s (at ~3g).

So for a first draft it's a wrap, pending critic, suggestions, wishes?, or headsup, it's ready to go ( readme, SC4 files included). Hope you guys like it.
 

Attachments

  • EA Hyperion Cruiser.zip
    5.3 MB · Views: 1

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
I don't think 8.4 million metric tons is the right mass. While it isn't exactly a small spacecraft, something with this density should collapse into a black hole. Those numbers come from the b5tech.org page, the Omega destroyer there would weight 26000 tons per meter of ship. For comparison the largest super tanker ever build by displacement is at 2600 tons per meter fully loaded, and that one was merely 414 meters long or 1/4th of a Omega class.
 

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
Yeah, I was questioning the mass as well. It steers like a black hole at least!
One can have big discussions about possible future tech weights, generally tending towards lighter though? I'm no Babylon5 insider ( I guess this one's for the fans) and I'm fully open to suggestions for mass, other stats.
 

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
Yeah, I was questioning the mass as well. It steers like a black hole at least!
One can have big discussions about possible future tech weights, generally tending towards lighter though? I'm no Babylon5 insider ( I guess this one's for the fans) and I'm fully open to suggestions for mass, other stats.

Well, as if such shows would bore us with numbers. :D I would divide the mass numbers at least by 10. If you can calculate its volume, I would use a maximum density of 2 tons per m³ of volume, more realistic would be 200 kg/m³ to 400 kg/m³ for a machine that isn't a solid block of very dense metal.
 

Buck Rogers

Major Spacecadet
Joined
Feb 26, 2013
Messages
245
Reaction score
192
Points
43
Funny, I ran it through ShipEdit for half an hour, went with 500 kg/m³ = 7.9 M tons. But the mesh is not ideal and should defineately be less, hangars etc...
I think 1.8M tons (even with armour) should suffice. I'll revise after feedback with any other changes.
 

Luke Reichelt

Active member
Joined
Oct 29, 2012
Messages
251
Reaction score
62
Points
43
Location
Manitoba
The vessel works pretty well so far, although as you said it's a bit sluggish. Also, including some hover and reverse thrust would definitely be advisable. In order to make the vessel at least somewhat maneuverable, I recommend increasing the altitude thrust by a factor of 10. Likewise with the main thrust.
 
Last edited:

Urwumpe

Not funny anymore
Addon Developer
Donator
Joined
Feb 6, 2008
Messages
37,537
Reaction score
2,272
Points
203
Location
Wolfsburg
Preferred Pronouns
Sire
The spacecraft should be turning fairly slowly, since it is quite long and has no artificial gravity magic. While most of the crew might be concentrated near the CoG, it could still mean about 300 meters of radius. It should maneuver more like a supertanker and require a lot of thinking ahead to maneuver.
 
Top