Newtonian Aurora

[Rastaman]

.... except their is no darkness to sensors!

I am really interested in seeing how the sensors come into play. Since this is combustion based thrust, and hard science based, your pretty much NOT having any issue detecting anything out there. Ships are HOT compared to space, even if they are not at full thrust.

Is this confirmed?

[Steve Walmsley (OP)]

A quick update on how things are progressing. I have had a frustrating few days with moving ships towards planets. The basic issue is that with Aurora-style orbital movement planets make sudden jumps every few days. This is a far more significant issue when ships are expending fuel to make course change and decelerations. In fact, so much of an issue that I came to the reluctant conclusion that orbital movement is going to have to take place a LOT more often. After trying a few different options, I have settled on the start of every increment that is longer than an hour. While this means that a planet might take slightly longer than its normal year to make an orbit if you use a lot of short increments during that year, the negligible gameplay effect is acceptable compared to orbiting planets even during 5 second increments.

This introduces a new issue though. Ships are slowing down to reach a planet and then the planet is moving slightly at the start of every increment, which leads to the comical sight of ships chasing planets around the map, with the planet keeping slightly ahead of the ship. Well, comical at first - now frustrating

I have tried a few quick fixes but I think that for movement purposes I am going to have predict the future positions of planets in the same way that missiles predict the future locations of ships. This doesn't sound too bad until you consider that a moon could be orbiting a planet that is orbiting a star that is orbiting another star that is orbiting a third star. Some coding required.

Shipyards are now working as discussed, with a few small changes. You have shipyard hub modules, capacity modules and slipway modules. They are separated for commercial and military so you have six in total and they are built only by construction factories not shipyards. A hub includes one slipway and 1000 capacity. Assembling and disassembling shipyards requires time and a small amount of wealth but no supporting infrastructure. This means you can create very large shipyards more easily than before and also you can dissemble several shipyards, move the modules in freighters and then reassemble them in a different configuration. Commercial and military cost the same and take the same time to assemble. However, commercial are 3x larger to move and have 10x capacity. I'll post more details when I have time in the rules thread.

Beam fire controls are now created using the same design process and background tech as active sensors and missile fire controls, except that missile fire controls have 3x active sensor range and beam fire controls have 1/3 active sensor range (technobabble being that MFC just paint the target for a missile that can change course en route whereas BFC need very precise information on exact location, heading, speed and acceleration)

And here is a quick shot of the unfinished battle overview window. As you can see, you will have far more detailed control when you set up firing solutions and you will able to modify the parameters for targets while missiles are in flight. This is because unlike standard Aurora, missiles will be heading for a predicted intercept point, not the target's current location. I haven't decided whether fire controls should be able to pass on a change of target though.



Steve

[UnLimiTeD]

Level 2 Epic.

[Beersatron]

Level 2 Epic.

Level 2 brain ache more like

[chrislocke2000]

Level 2 brain ache more like

Probably! But I'm expecting it to be a very enjoyable one  I'm looking forward to doing plenty of AARs on my various disasters.

Steve, on the moving to planet issue is this arising because you have ships slowing down to 0 rather than slowing down to the speed of the planet? I assume when ships leave a planet they start at zero rather than a speed relative to the sun(s)? If thats the case, when ordering a move to planet could you take the planet orbital speed, multiply by say 1.25 and then use this as the stop speed. Once the ship "hits" the planet it then just switches to a zero speed state. I'm not sure how fast some of the planets can orbit but would have thought this would not have too much of an impact on fuel saving issues.

[sloanjh]

I have tried a few quick fixes but I think that for movement purposes I am going to have predict the future positions of planets in the same way that missiles predict the future locations of ships. This doesn't sound too bad until you consider that a moon could be orbiting a planet that is orbiting a star that is orbiting another star that is orbiting a third star. Some coding required.

I actually ran into this about 6 months ago when I was fooling around with SA/Aurora-style  (i.e. max velocity, instant acceleration) intercepts.  It (the orbits of orbits of orbits) is a REALLY nasty problem.  A couple of suggestions:

1)  Hierarchically throw away detail.  By this I mean you want to predict the intercept to the outermost orbit (i.e. the 2nd star) 1st.  That will give you an intercept time.  If the intercept time is long compared to the next period, stop there and pretend you're aiming for the central body.  If it's not recursively go to the next body.  As an example in the Earth/Luna system, first you'd calculate an intercept to Sol.  If the time was more than a year, you'd stop and simply aim at Sol.  If the time was less than a year but more than a month, you'd calculate the intercept to Earth and ignore Luna.  If less than a month, you'd simplify the orbit of Earth (see below) and intercept Luna.  Note that this assumes that an orbiter has a significantly shorter period than an orbitee - if that's not the case you've got a big problem

2)  Use a "constant acceleration" approximation (i.e. a Taylor expansion) to approximate orbits whose period is much longer than the intercept time.  In the example below (assuming Sol is not moving), when aiming at Luna you would not model Earth's motion as a circle.  Instead you'd calculate Earth's velocity and acceleration.  (I would calculate them relative to Sol, then add in Sol's velocity and accel to get a total.  This is because, relative to Sol, they'll always have the same magnitude and simply have different directions.)  You'd then approximate Luna's motion as a circle orbiting a object moving along a parabola.  The reason for doing this is that a) it makes the math easier and b) it's recursive - no matter how many nestings you've got, you're still always solving the same problem.  This is simply a more sophisticated version of what you're doing right now, i.e. simply using the 0'th derivative (position) to approximate the correct course.  When you get really close to the target (say an intercept time of less than Period/4), then you can approximate the targets motion too, at which point you're calculating an intercept to something with a simple parabolic path (i.e. intercepting a constant acceleration body).

3)  Looking at the above, if the "circle around a parabola" problem is too hard, then you could just ignore the orbiting body until intercept time was less than Period/4, then pop over directly to approximating its motion with constant acceleration.  So at that point the two changes  to your existing algorithm would be a) ignore nested orbits until the intercept time drops to some fraction of a period and b) approximate all orbital motion as constant velocity (no accel) or constant accel, which allows you to use the same intercept code you'd use for ships.

4)  Another thing I just thought of:  when calculating the intercept time to see if you should igore a sub-orbit, I really meant "intercept time to the closest point on the orbital circle".  In other words, you should use the motion of the central body, but subtract off the orbital radius from the distance to the central body (you should probably use this as the course target as well).  This will keep you from getting falsely small time values if you happen to be inside the orbit of whatever you're chasing.  So the real suggestion when ignoring inner orbits is to calculate the intercept to the motion (due to central body motion) of the closest point on the orbital circle to your current position.

Hope that helps....

John

[jseah]

You could calculate the Hill sphere for various bodies in the solar system, then apply gravitational acceleration to ships within them?  Then ships can do parking maneuvers. 

Outside those Hill spheres, ships accelerate wrt. the sun (binary or more systems default to primary star unless ship is inside the Hill sphere of secondary star)

In this case, you don't have to worry about "catching up" with planets that run away.  Since your ship would ideally want to retain orbital velocity (assume circular orbit), you will be moving with respect to the planet. 

[bean]

Level 2 brain ache more like

You've obviously never played Attack Vector: Tactical.

The intercept problem is a tricky one.  However, due to the hill sphere, I'm fairly certain that you can't have a level three body with a period approaching that of the level 2 body.  Unless it's tidally locked.
Speaking of which, will we be able to stick stuff at the lagrange points?  Not like they are now, but for real?  Also, probably only for planets, for simplicity reasons.

You could calculate the Hill sphere for various bodies in the solar system, then apply gravitational acceleration to ships within them?  Then ships can do parking maneuvers. 

Outside those Hill spheres, ships accelerate wrt. the sun (binary or more systems default to primary star unless ship is inside the Hill sphere of secondary star)

In this case, you don't have to worry about "catching up" with planets that run away.  Since your ship would ideally want to retain orbital velocity (assume circular orbit), you will be moving with respect to the planet. 

That's a really good idea.  While aiming where the planet will be is a good solution, adding the Hill sphere can reduce issues in that regard.

[sublight]

Ladies and Gentlemen, our ships are moving too fast.

When a rail gun does more damage than a nuclear warhead kg per kg, something is quite possibly wrong.

At starting tech, a nuclear warhead does 100 kTon per ton, or 418 GJ/kg.
If the sample campaign ship dropped a 1kg rock out the window after using 1/10th the available deltaV (2,474 km/s), then the rock would do 3,063 GJ/kg.

I'll give the nod to jseah for being the first to comment on the reason and implications last page, and admit it took a few days for the implications to sink in.

For that matter, since sorium fuel is going to be so much more plentiful now (relative to other things), we could have a cheap version of a nuclear missile that uses sorium reactions instead of nuclear warheads.  

An order of magnitude less powerful per ton, but able to convert all remaining fuel to explosive yield, plus cheaper.  

Only, a Sorium bomb is likely to be more powerful, not less powerful, than the nukes. At maxium engine size and the most favorable Thrust / Fuel Consumption Modifiers (but neglecting the base fuel efficiency tech) leaves Sorium derived fuel at 7.8E15 J/Kg energy density. A 0.01% energy efficient sorium bomb would have double the output of the starting nuclear warhead.


So what can be done?
Two solutions come to mind:
Option A: Increase fuel consumption. A 40x increase in fuel consumption would give Sorium equal recoverable energy density to nuclear warheads when they are both at the starting fuel efficiency/warhead size tech levels. For simplicity, call it 60x increase and replace 'liters per hour' with 'liters per minute' The sample campaign Vanguard now has a hair more than 412 km/s delta V to work with. That really isn't that bad compared to the current human probe speed record. Since this will be painfully slow by the old Aurora standards, the old hyperdrive would probably need to return for in-system transit outside of planetary gravity zones, with the old hyper-limit applying just to system jumps. Maybe 10x movement while under hyper, leave big bright signature even while coasting, can't fire weapons or use sensors while under hyper. I guess we can let them be assumed to have their base speed when calculating railgun collision damage, and of course return to normal base speed when exiting hyper.
 
Option B: Grand Handwavian. Replace 'TransNewtonian' with 'PostEinsteinian' or 'dimensionally resonate.' Ships are still zooming around the map as fast as before thanks to their anti-gravity sorium-infused repulso-thrusters. Further, if we go this way and accept that this is the same fantastic Aurora space fiction just using newtonian motion, we shouldn't stop the scale-up with propulsion. Are the titanium hulls tin-foil pathetic? Well then: thanks to dimensionally-locked Duranium lamination, the armor is 10x tougher than ever! (I'm assuming current armor is already 4x better than theoretical real world, so 10x more might bring it closer to the sorium fuel.) Maybe the hull spaces are twice as tough, and are now 5 layers per cm thickness, and only added in cm groupings.

[jseah]

More like 1000x tougher.  You need armour to start in the gigajoule range for it to be worth anything. 

EDIT:
Does result in the very interesting scenario of enemy ships decelerating wrt to you in order to survive railgun shells. 

Nukes will need to contact to actually do damage.  Although if they do acheive a contact hit, it's still probably bye bye ship. 

EDIT2:
Whuffie get!  =P

[bean]

Definitely in favor of option A.  Actually, reduce both exhaust velocity, and acceleration.
Actually, even better idea (courtesy of AV:T):
The standard drive is in the .01-.1 G range, and has a max delta-V equal to maybe 1/10th that we currently have.  However, military drives, and only military drives, have a boosted thrust mode, which increases thrust by a factor of about 20, but increases fuel consumption the same amount.  This way, we get lower kinetic death quotient, and maneuverability becomes a factor again.

[UnLimiTeD]

Well, essentially, for in-system Hyperdrives. we'd have to have a new hyperlimit system.
Suggestion:
Have one from the Star, 1 Au per solar mass (based on our home system), and maybe a million kilometers per [planet size (how ever we define that)]^1.1.
The ^1.1 is meant to result in low values on small planets, so that we can cut off and abstract away; A large Jupiter-like body with two dozen moons would only have one hyperlimit assigned to it.
Thus, movement would be relatively slow near planets, but one could cruise faster in between; The inter system would be more secure due to the stars hyperlimit.
Maybe, a ^0.95 on the stars limit would result in bigger stars with huge systems not having an equally huge limit.

But that would have to be done drastically different from Aurora is the actual hyper-system.

Either, we require ships to have a jump engine, then it could just be a modified engine that allows a speed boost for low, ongoing fuel consumption, only in system outside of the "inner" hyperlimits.
The speed boost shouldn't be a flat x10, it should maybe start at x2 and then increase by 0.5 or 1 with every advancement of Hyper-Jump technology.
We could also go the way of having special thrusters, this would allow us to specify a minimum size and maximum size efficiency, where ships get a speedbost based on how large they are compared to their thruster array.
I can see a combination of both, where small defensive ships get a small hyper-thruster and thus have no need for a larger jump engine.

As for the fuel efficiency, I think it's ok to start higher than what we have today, because in this case, with a bit of handwavium in place, we can go for gameplay concerns as well.
Once it takes a month of acceleration to reach the projected lethal speeds we try to avoid, we don't need to ramp up the fuel consumption any further, even if that still means a silly high fuel efficiency; as much as I love logistics, that might be a bit much.

Maybe, higher level engines should give less extra output, and more bonus to efficiency, with less cost ramp up than we are used to by Aurora.

/rant 

[sublight]

The higher fuel consumption + hyperdrive theory is to limit the true speed and thus the incredibly rail gun power, while allowing system transit to be carried out in a reasonable time. Where before a military ship might accelerate to 2,000 km/s for an attack run, with a 60x fuel consumption jump the same ship burning twice the fuel will only hit 67 km/s for the run. That works out to about a 3x energy increase for the rail gun round compared to the currently troublesome 440x energy increase. Kinetic kill overpowerdness largely solved. The hyperdrive then makes in-system transit acceptable again. Now, how slow is acceptable? If a starting-tech ship only does 50km/s acceleration runs, and we want 200 km/s interplanetary speed seen in the early game, then having a 4x hyperdrive would need to be the starting tech.

Suggestions if increased fuel and added hyperdrive
First, no solar hyper-limit. Use the Planetary Hill Zones already suggested for simplifying planet intercepts as local hyper-limits instead. Technobable says hyperdrive are unable to function when influenced by multiple bodies. Ships/objects within a planet's hill zone get moved to keep relative position with the planet, and can't hyper. Ships outside move independently and can hyper. This would make the system ship movement start to mirror the Galactic ship movement on a smaller scale.

In Transnewtonian Aurora the hyper is a fixed 10x, with tech reducing added mass. In Newtonian Aurora I'd suggest making the hyperdrive a fixed mass increase (+50%?) with tech increasing the hyper speed. Hyper speed might starts at 4x and increases by +1x with each tech advancement. (I think starting at 2x will be too slow) Ships lacking hyperdrives become the dedicated planetary-defense craft.

Astroid Belts are reefs. With all the interception issues astroid movement gets disabled. Instead of individual astroids having Hill Zones, the entire astorid belt becomes a hyper-blocking hill-zone barrier. This could create inner defensive zones against interstellar foes jumping in-system.

[chrislocke2000]

I must admit I'm not too keen on the idea of having three propulsion methods in the game still and I think hyper drives could cause even more issues-

- If it's an instant transit from normal drive to hyper drive you are going to have a non Newtonion change in speed which means ships will be able to pretty much dodge any incoming missiles or other ordnance which are stuck under Newtonion rules.

- If it's a non instant transit then you go right back to the original issue of ships travelling too fast for big periods of time when they can be one shot killed and may be particularly prone when they leave hyper transit and are effectively unable to make course corrections until they slow down enough for the engines to have a reasonable relative effect again.

- Having ships both unable to fire and immune to attacks in hyper just compounds my first point. If ships are vulnerable in hyper then they are at an even bigger risk of one shot kills - especially if they are heading towards an enemy.

Therefore I think that, all in all, hyper would cause more issues then it solves.

As it stands the balance on speed of exploration and development seems OK. If ships were slowed even further you may have to increase ship production capabilities to allow players to have enough ships to continue to achieve anything in a reasonable time scale.

I quite like the idea of having to seriously hit the brakes if I want to fight and the damage potential if I fail to do so. I do think defensive armaments need to be beefed up a bit though to help make those hits less often. I think there could also be some very interesting interplays between better lasers that could be effective at longer ranges v rails that will be pretty devastating at close range.

One other thought, would the energy wave of a nuke be one hell of a great Whipple shield. You probably only need to get the new 5-10k away from the ship so I guess you would have reaction time to do this?

[sublight]

That... is a good point on the hyper dodging. A very good point. Having a large warm up might help there: if engaging a hyper drive took an hour, then a hyper ship could realistically only dodge once in an engagement by exiting hyper space.

Currently speed and development seem balanced. The issue is combat damage. Currently Newtonian Aurora looks to be balloon-tack-tag. Only active defenses and dodging will work. It might be fun to play a game like that, but the after-action fiction reports do sound better if damaged survivors exist.