"Orbital Space Combat" Topic

Vector-based space combat games have always kind of bothered me- they claim realism, but completely ignore the gravitationally-based maneuvering that will define 'midfuture' space combat.

I've been tossing around concepts for an orbital-maneuvering-based hard-sci-fi game (for GALAXIA); my last prototype board wound up as a 20-inch-square polar plot. I'm really having trouble with this; would the best idea be to have ships at the same altitude remain stationary relative to each other, with varying velocity vectors based on orbital altitude?

I would look at Hard Vacuum as a good example.

Is this fighter combat? Ships capable of generating thrust and being large enough to travel between start system would probably not get close enough to a planet to be bothered by it. Unless it was a speed boost situation where they sling shot around planetoids.

A circular grid pattern would work better. The planet at the center with rings marking various levels of atmo. It would look more like a race track with wider sections at the outside to represent the faster speeds. You'd be taking your speed reference from the planet so stopping is just geosynchronous orbit. A larger planet would require a higher base thrust to stay in orbit and anything under "0" would require shifts to a closer track.

If your that close to the planet then it is just a race around the planet with ships jockeying for firing position as they spin around the planet. It would be very similar to the chariot racing games mechanics wise. You could have slower troop transports steadily dropping towards the planet as they shift along the track at one or two spaces per turn and fighters lapping the planet to get pot shots on them. Defenders fighters would be blocking and attacking. Not unlike roller derby :)

Curvature of the planet would restrict firing to only a few spaces. Depending on what track the fighter was in. Closer tracks would be smaller and the same speed relative to the planet would take you around the planet more then it would at the farthest point.

It could be done and might actually be rather cool.

To be honest, orbital maneuvering (as opposed to interplanetary maneuvering, though properly that is a solar orbit) is extremely hard to tackle as a board game; one reason that most vector based games don't even try to deal with it! It's a hard concept to wrap your head around, with 'lower' orbits being 'faster' and then what happens when you have a ship on an elliptical orbit intersect the orbit of a ship with a circular orbit, and what about ships at the same altitude but orbiting in opposite directions etc, etc?

My very amateur two cents is to pick a 'reference' altitude and have that be 'stationary', at least for all ships orbiting in the same direction. Then ships with different orbital inclinations and altitudes would have a relative velocity to the 'reference' altitude. Still a challenge to design though; deep space can be 'flattened' and not damage the game too much (dodges rocks thrown by Attack Vector fans) but orbital space is by it's very nature *extremely* curved….

-Will

It would look more like a race track with wider sections at the outside to represent the faster speeds.

See, here's where it gets counter initiative, it's actually the the 'lower' orbits that are 'faster', since their speed it higher relative to the Earth's surface. An object in LEO orbits once every ~90 minutes at moves at 6-7 km/s, while an object at GEO (much higher altitude) takes ~24 hours to orbit the earth once and only moves at ~3 km/s… So the map should actually have less spaces closer to the planet, and more as you get away from the planet.

Geostationary orbit would be the perfect 'reference' altitude though.

-Will

Two vessels orbiting with the same apogee and perigee can still have a large relative movement (the most extreme case being when one is in a prograde and the other a retrograde orbit). The problem with a realistic space game is that it really IS Rocket Science, and so a lot of stuff isn't particularly intuitive or conceptually easy.

Caveat: This is off the top of my head, and so may be utter bilge. Suppose Red and Blue are travelling East in the same orbit. If Red accelerates to the East, she will enter a higher orbit, and find herself paradoxically moving slower relative to Blue, and to the planetary surface. Conversely, she will enter a lower, faster orbit by accelerating West. Now for the tricky part; Red's captain decides to accelerate to the North, at right angles to the ship's flight path. Red enters an orbit defined by the vector sum of her previous path, and the acceleration granted by the engine burn. I think that she would enter a higher orbit (along the hypotenuse of the two vectors) inclined somewhat to the North. I'm not very sure what would happen if the captain decided to apply thrust directly toward or away from the planet. Also, not every orbit is circular; a ship in an elliptical orbit will be moving appreciably faster at perigee than at apogee (sweeping out equivalent areas of the orbital plane, in accord with one of Kepler's laws). At this point I usually reach for an aspirin and a copy of Full Thrust, and refer you to a better source.

This is the Atomic Rocket website:

link

It is a good overview of hard SF considerations for realistic spaceflight. Good luck with your project, and keep us posted!

See you later, space cowboy.

Ron

Honestly you would be better modeling the board or table space in terms of energy expenditure rather than distance. It is counter-intuitive without a bit of explanation though. However if you want realism, it's the best way to go in terms of eliminating some heavy calculations. Altitude in Air games is important. In a near-planet game it's vital, I believe. Horizontal movement is easier than climbing. You'll cover 3000 miles horizontally to climb 100 miles in an Earth gravity well.

Coelacanth has it right, and explained it better than me.

Applying thrust directly towards/away from the planet I believe will both increase the eccentricity of the orbit and 'shift' both the apoapsis and periapsis in the same direction; so if thrust directly away from the planet your apoasis will rise *and* your periapsis will fall relative to the planet (and vice versa for thrusting directly towards the planet). Yep, rocket science is weird.

I'd also consider buying Kerbal Space Program and playing around with spacecraft in low orbit and practice intercepts with other spacecraft already in orbit and the like; you'll learn a lot.

kerbalspaceprogram.com

-Will

I agree, using a circular grid would be better.

Perhaps several, or numerous bands of rings around the planet, segmented, to keep track of the movement rates.

Then, adjusting for speed loss, or increase, as you move toward, or away from the planet, apply thrust, etc.

You might be able to keep the rules fairly simple, in order to avoid headaches, and to just have a fun game.

For elliptical orbits, you could use a drawing program to create some of those, and then put hash marks at various points around them to help keep track of the distances moved.

Moving too quickly in the lower atmosphere, or at too steep an angle towards the planet can result in either bouncing off of it, or burning up, so should be avoided. Moving too steeply away could potentially mean you leave orbit permanently, and don't have the fuel to return to Earth.

An alternative map suggestion:

If the ship is orbiting exactly over the equator, the orbit will be a straight line. As the inclination grows higher, the amplitude of the "wave" increases. One could have a few transparent templates for different inclinations, and register marks on the map to advance the track each turn. Height could be indicated by a marker on the flight stand. For the sake of simplicity, a few representative altitudes and inclinations might do, rather than computing an exact trajectory for each object.

Ron

P.S. There is a freeware space flight simulator called Orbiter (created by Martin Schweiger).

orbit.medphys.ucl.ac.uk

That's a neat map.

Of course, you'll need to displays, e.g. one like the above showing the position in relation to the planet, and another one showing the height of orbit above it.

For a simple game you might take the two ends of a Circus Maximus map and put them together. Then you would have to come up with rules governing changing orbits.

On a less technical note, there was a boardgame called Orbit War by Steve Jackson Games. It used a hex-based map-board, but there might be some things about it that could prompt some ideas.

Description and pics here:

link

Keep in mind that gravity is an inverse-squared thing. Ships capable of interstellar travel would basically ignore gravity most of the time.

Even the vaunted "slingshot effect" is nothing if you're going fast enough.

Being a rocket scientist, you'd expect that I could add to the conversation, but the basics have already been covered. Circular orbits are easy to model, but the transfers less so, and complex eliptical orbits get out of hand really quickly.

G.O.B.S. has an optional system that allows for natural, vector based orbits. It's based on a hex system I devised for another game which used much larger planet radii than G.O.B.S. does, but it works fine either way. It assumes the reduction of gravity with distance from the planet's center of mass, but limits this for simplicity to "zones" of gravitational acceleration. The closer to the planet, the greater acceleration within that zone, and vice versa. The movement system is modified from GDW's Triplanetary. Feel free to give it a shot for your purposes. thegobspage.com

I've started looking at the distances involved, and want to include Lagrangian points (in-universe, used as Alcubierre drive jump points) and lunar maneuvering.

CorpsCommander, I like your suggestion of energy-based diagrams. Right now, I'm creating a revised prototype board incorporating delta-v costs for maneuvers between orbital states (LEO, geostationary, L4/L5, etc.). It will be set up on a hex background, which will be used to calculate firing range for lasers and coilguns.

[URL=http://s932.photobucket.com/user/Porty1119/media/image_zpsd83ed4a5.jpg.html]

This is my current draft board. It shows delta-v costs (km/sec x 100) for maneuvers. I'm kind of on the fence about whether or not the board should be a lot larger to permit for greater positional variety.

Take a loot at high frontier… it uses energy as the basis of its movement/"Distance" system. I imagine something similar might work for close in orbital games.

Wellll….here's my second draft board. RTJEBADIA, thanks for pointing out High Frontier. I'd been looking for a way to at least suggest Hohmann transfers and rounded orbital trajectories.

Each circular space represents the distance a spacecraft may move in one turn. Orange spaces show locations where a transfer may be made ONLY at that location, while red spaces show transfers that may be made at ANY POINT in that orbital altitude. 'G' represents Geostationary Orbit, and 'L' represents Lagrange points*. The number below a transfer space shows the delta-v cost of the transfer in km/sec * 100.

*I wasn't able to find delta-v costs to/from EML3. If anyone has those on hand I would greatly appreciate it- I found myself using EML1 values and trying to ignore the inaccuracy.

Nice work, make sure to show us the final game.

IIRC Battlespace/Aerotech had some basic rules for planetary gravitational effect on orbits and near planetary combat. Probably past that already, but might want to take a look.

I'm thinking about a similar concept for space opera games, though there I'll be using singularities. Want to build a board with a sinkhole/vortex in it, so I'd need depth on the board. Toying with the concept of using a mylar sheet that has some elasticity and actually twist the fabric of the sheet to represent gravitational effects – but still just a concept in my mind. :D

Minor threadomancy here, but I have a meaningful update.

So, I adapted my first sketch (the hex-thing) to a 20"x30" sheet of foamcore. A buddy and I ran the first-ever playtest this Monday. The mission was pretty simple- a Sinterian VLAC-K (kinetic-armed very light assault craft, thing corvette) with some drone support jumped into L5; its mission was to retrieve a crippled LAC-P (patrol light assault craft). The UNCS had a laserstar in geostationary near L1, two 48-round box-launcher missile satellites (1 each near L4 and L5), and eight C85 Dagger SSTO fighters. It ended with two fighters destroyed, several hundred missiles expended, the CL-PA salvaged after around an hour's work, and not a scratch on the VLAC-K. I was extremely inefficient in managing my C85s- I launched piecemeal after landing to rearm, and never accumulated sufficient concentration of warheads to punch through the VLAC-K's six point-defense lasers. The laserstar never had a chance to fire, and the box launchers were more unlucky than anything else.

I deliberately wrote combat rules to be extremely simple, and it worked. Turns don't even take ten minutes, record-keeping is minimal (I'm fiddling with a design for a unit base indicating prograde or retrograde orbit, as well as a fuel dial) to nil, and units have enough attributes to permit substantial variety and future rules for special munitions types, EW, et cetera. Turns are set on a fifteen-minute timeframe, meaning that battles play out over several hours in-universe. Going by the rough rule of thumb that games should run at a pace not significantly slower than the events they depict, this was a success

Setting up the board was a minor pain. I had to print and cut a regular hexagon in cardstock, then trace it with an opaque white paint-marker. I'd originally intended to have delta-v costs for each hex change, but dumped this (as well as doing the actual calculations for each spacecraft and all of its potential payloads) for simplicity. It makes the assumption that all hex changes (aside from natural orbits, obviously) use roughly the same delta-v. My last simplification/assumption is to ignore the burn out of the Hohmann transfer orbit, and just assume that it happens at a later time.