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[Tacomagic]

So... If a minecart hits a wall in midair, do the contents stay inside, or do they get sprayed?  That could be important to the setup.

[Girlinhat]

So... If a minecart hits a wall in midair, do the contents stay inside, or do they get sprayed?  That could be important to the setup.

Any time a cart stops suddenly, the contents leave.  However, carts can jump tracks, and to my knowledge a Cart Stop set on highest friction will never eject contents.  So you could easily have a launch ramp, open air, and cart stops set to full friction to 'catch' it.

[Urist Da Vinci]

The only serious problem is that you cannot launch directly upwards, you can only go at angles.  This means the higher you want to go, the further sideways you have to go, and embark size becomes a limit for height.

Even then, minecarts have a terminal velocity (I believe rolling downhill is faster than the fastest set of rollers) which means a max height.  Still, if you call Z+3 to be 'space' then sure!

Also keep in mind what this means for invaders.  If you start on a flat map, and never build up, nothing should fly above you.  HOWEVER building walls creates floors, which means you've 'built up' so you can only defend yourself with statues and ditches.

Yes, embark size matters. I was able to gain 15z in one embark tile.

We are relying on the "impulse ramp" exploit, not rollers, so we might be able to launch 20-30z into the air. My test setup used no rollers, and a dwarf rode the cart to get it started.

On a flat map, the surface level and the level above it are both allocated. This might be because of the trees. Things can fly over the trees or walls/statues at ground level. If you build up, then another z-level is allocated.

[Girlinhat]

Oh I see!  I didn't realize quite what impulse ramps were...  Much more eloquent than "minecart booster" for sure!

I like how the wiki lists the friction values of various tiles.  But does anyone know the acceleration value of rollers?

[gchristopher]

Solved the problem. The game doesn't allocate z-levels in the sky except for the two closest to the ground unless something taller is built in that area block. I am building a staircase tower off to one side of the launch ramp, all the way to the top of the map.

It's more granular than just z-levels, too. It might be by 16x16 chunk within the z-level?

I once built a track stop that dumped west on the most northwest point of a constructed tower, and when I placed a cart containing magma there, the game kept running, but had a perpetual string of glitchy messages. I'm guessing it was related to the magma being dumped into a horizontally adjacent unallocated tile.

Building either north, west or up resolved the weird liquid dumping behavior.

[gchristopher]

Oh I see!  I didn't realize quite what impulse ramps were...  Much more eloquent than "minecart booster" for sure!

I like how the wiki lists the friction values of various tiles.  But does anyone know the acceleration value of rollers?

Rollers set the cart velocity instantaneously to the speed value for that roller. (50,000 for "highest") So the cart undergoes instantaneous acceleration.

Impulse (or downward) ramps act in a (mostly) more conventional manner of applying a fixed amount of acceleration per tick. (5,000) Since a tile is.. 60,000(?) across (I think), a cart spends several ticks on the first few impulse ramps and leaves going much faster than the 50,000 highest roller speed.

The max speed is 270,000. I don't know if it's per-orthogonal direction, because at that speed it's crossing several tiles per tick and the game implementation starts to get confusing. It takes on the order of 50-ish impulse ramps in a row to get top speed, but you can send a cart back and forth up stacks of rows of ramps to make it fit in less horizontal space.

The exact position (offset) of a cart on a tile can sometimes be really counterintuitive once you factor in derailing effects and bouncing off walls in corners, etc, etc.

Yes, embark size matters. I was able to gain 15z in one embark tile.

So cool.

Do you know if it's meaningful to express the launch direction of a cart in terms of vertical angle? (i.e. a cart launches 45-degrees up from horizontal?) Does the pre-launch velocity get set into horizontal and vertical components that'd you'd expect from trigonometry of the angle? (I suppose those are interchangeable questions.)

Did you see a constant per-tick downward acceleration due to gravity? Was there any sign of air resistance or other horizontal deceleration in flight?

[the1337doofus]

Just posting to watch; You people are insane smart, and I want to see where this goes, maybe learn a thing or two.

[rhesusmacabre]

CHALLENGE: launch a creature at least 15 z-levels into the air and have it land safely (unharmed, uninjured). Landing on a platform in midair is acceptable (and recommended).

I'll see your 15 and raise you another 11! But we'll get to that...

To get around having to "raise the sky" I decided to dig a 90-tile long, 30-z deep trench, and have the accelerator underground.

When accelerated by 51 impulse ramps and hitting the ramp, the path of the cart was as follows, with each x representing 1 tick:

Spoiler (click to show/hide)

                                                                           x xx
                                                              xx x x x x x      x x x x x x
                                                        x x x
                                                    x x
                                                x x
                                            x x
                                         x x
                                       x
                                   x x
                                 x
                              x x
                            x
                          x
                        x
                      x
                    x
                  x
                 x
               x
             x
           x
         x

       x
     x
    x
___▲█

The trench I built ran out of space around this point, but the rest of the arc can be more or less extrapolated. The peak here is 26-z up and about 74 tiles along from takeoff, and reached after 40 ticks.

Crucially, the only accelation is vertical and not horizontal. This means another ramp can be built at a higher level and the minecart can be launched on another arc, raising the prospect of a system of launches from the depths. In order for a cart be relaunched it must first "make contact" with a surface, which it can only do when travelling downwards, so any extra ramps have to be placed at least after the highest point reached. I did manage to achieve this, although my minecart quickly ran into the hitting-the-sky problem highlighted earlier. It also accidentally ran into something else:

Spoiler (click to show/hide)

You may have noticed the red x in the chart above, 13-z above takeoff. This was the initial point of impact. The cart lost some of its momentum here and failed to reach its normal height. The eagle, however, was propelled along the cart's initial arc and hit the ramp I had constructed at the peak. (It was then quickly collected and dismembered by my butcher.)

As for dwarven flight, well I removed the top ramp and replaced it with a straight section of track and a stretch of track stops. Six was enough to stop an unmanned cart, and when I then tried a live test it worked out just the same:

Spoiler: 26-z up (click to show/hide)

[Sergarr]

Now we must use it for Dwarven Anti-Air Defence!

[Xinael]

A thousand nations of the Dwarven empire descend on you! Our minecarts will blot out the sun!

Then we will fight in the shade.

[Girlinhat]

A thousand nations of the Dwarven empire descend on you! Our minecarts will blot out the sun!

Then we will fight in the shade.

Implying the elves have that much courage...

[Tacomagic]

I'm thinking fire bin payloads would be appropriate.

[Urist Da Vinci]

...

Do you know if it's meaningful to express the launch direction of a cart in terms of vertical angle? (i.e. a cart launches 45-degrees up from horizontal?) Does the pre-launch velocity get set into horizontal and vertical components that'd you'd expect from trigonometry of the angle? (I suppose those are interchangeable questions.)

Did you see a constant per-tick downward acceleration due to gravity? Was there any sign of air resistance or other horizontal deceleration in flight?

Ran a few tests. After a few high velocity collision deaths, one of the testers went berserk while in the cart during the launch sequence, but that didn't prevent him from being sent into orbit.

A minecart is travelling along a rail at velocity V. It hits the ramp and launches at a 45° angle. The new vertical and horizontal velocity components are both V (I know that this violates physics!). The horizontal velocity is constant while in midair, whereas the vertical velocity decreases by 4900 per tick. The cart otherwise behaves as per known minecart stuff.

We should be able to launch carts ~150 tiles sideways, given a map with enough airspace and length/width. Also, I predict that carts have enough velocity to clear a z-level or two of water and still be moving upwards. They wouldn't get as high as 26z, more like 5z tops because of the massive water friction. We could make a submarine launch system, using careful hatch, door, and pressure plate timing to only flood the firing chamber at the last possible moment. May even be able to shoot ‼minecarts‼ out of magma pools.

[Girlinhat]

I'm thinking fire bin payloads would be appropriate.

Why complicate things?

Just use magma itself.  In fact, semi-related, I'll be preparing a minecart magma cannon for a new fort.

[BastiBasti]

Wow. So is there a possibility for A-A flak magma minecarts? I mean, does a liquid inside the minecart greatly increase the friction and I know a dwarf riding a minecart won't die due to magma filling it, but if said a magma minecart hit, lets say, a Roc or a giant eagle would the magma harm the creature? Would we still be able to predict course of said minecart? Would we be able to fill it with an explosive of sorts to either do direct damage, launch out platinum coins or something as flak or simply as a cluster bomb above a siege, effectively making dwarven artillery?

So many possibilities...