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[QuantumMenace]

Apologies if this has been discovered before, but it's hard to search for something like this.

One of the oddities about minecart physics is that if a cart derails and moves onto a ramp from the side, it will be considered "higher" and roll down off the ramp. That can be exploited to make it behave like an Escher drawing:(link)

Here's one possible layout. Make a series of 2x2 rooms connected to each other or hallways only by the corners. Preferably, at least one corner of each room should have no outlet. Build or designate 2 E/W and 2 N/S track ramps in a pinwheel pattern. These don't need open space over them.

Spoiler (click to show/hide)

Build a 1x1 retracting bridge in each room, in a corner with no outlet. This is because retracting bridges can scatter items 1 tile in any direction and might otherwise throw the cart out of the room. Connect the bridges to a lever. Use hauling routes or dumping to place a cart on each bridge, then forbid the carts.

Spoiler (click to show/hide)

When the enemy approaches, pull the lever. Without the bridge there, the cart will roll off the ramp onto the next ramp and so on, making a rotation around the room every 32 ticks. Since the cart is always on a ramp, no creature will stop its movement indefinitely. Generally any creature hit the first time won't be able to escape at all because the cart will hit it again before it can recover from the stun. Once the invaders are thoroughly pulverized you can pull the lever again to stop the carts.

Spoiler (click to show/hide)

Another option is digging 2x2 ditches in a larger passage and filling them with this hazard. I'm sure you'll find more ways to exploit this. Enjoy.

[Drazinononda]

Just so you know, I registered for this account just so I could congratulate you on your genius.

[slowpokez]

Just so you know, I registered for this account just so I could congratulate you on your genius.

Welcome to b12 one of the worlds last beacons of insanity!

Also:
If this thing is as amazing as you just described it this is truly a great day for !!science!!. Just brilliant.

[denito]

I'd been looking for something to do as a first minecarts project, I guess this will be it.  Hmmm...  I wonder if this can be combined with a magma-mister...

[Mura]

Congratulations.

[Urist Da Vinci]

I tried, but it seems like you can't use this to derail carts uphill. I wanted to make a free energy cartlift.

If we come up with a way to release the carts from the perpetual motion machine, I wonder if they "charge up" enough energy to go uphill?

[Mura]

I tried, but it seems like you can't use this to derail carts uphill. I wanted to make a free energy cartlift.

If we come up with a way to release the carts from the perpetual motion machine, I wonder if they "charge up" enough energy to go uphill?

I'm sure we can come up with ways. As for going uphill, I think you need rollers or dwarfs for that.

[denito]

I tried, but it seems like you can't use this to derail carts uphill. I wanted to make a free energy cartlift.

If we come up with a way to release the carts from the perpetual motion machine, I wonder if they "charge up" enough energy to go uphill?

Maybe instead of a loop use a zig-zag pattern?  Or perhaps a spiral accelerator, where the carts start in the center and make larger and larger loops until they exit?

[QuantumMenace]

Another thing to note is that you can add a second cart to the grinder. Haven't tested its effectiveness but it should work fine in theory.

I guess this is as good a time as any to discuss my other findings from my attempt to make a track switch with a sideways-sloped ramp intersection and a door blocking the straight route.

Using this as a loop or diagonal/zigzag won't accumulate speed because the cart loses its speed every time it hits a wall. However this linear accelerator works somewhat:

  -_#\-___#\--

That's a straight track, channeled gap (with ramp removed!), fortification, and track ramp in that order, followed by a straight track (may not be needed), 3 or so channels, a fortification and another track ramp, and so on. When a cart goes over a gap it will fly through a fortification, but the ramp on the other side still counts for momentum purposes. The tough part is that the ramp only counts if the cart is rolling on it and not flying over it, and it flies further the faster it's moving. There's only a certain amount of speed you can get before you can't get it to land on the ramp just right to keep getting more speed.

The other thing I found is that the game doesn't know how to handle the slope of intersection track ramps in some cases, and considers them to have no slope at all.

Code: [Select]

WWW   WWW   ..W
=+W   =+W   =+W
WWW   ..W   ..W
Where W is a wall and + is a NSEW track ramp, the case on the left propels a cart to the left. However, the other two don't make the cart roll in any direction. If you have a dwarf push a cart up a slope made of all-direction track ramps that only have walls on 1 or 2 sides, it will go all the way to the top! Strangely, a cart that starts moving because of rollers will instead move up 1 z-level and stop on the ramp there (maybe based on speed or something??). I still have to test if it will keep going upwards with alternating NSEW ramps and straight, non-ramp tracks. In any case, it won't roll downwards of its own accord, meaning you can make guided carts on ramps perfectly safe in theory.

Which brings up another, seemingly more effective linear accelerator:

_    _    _
  \+  \+

where \ is a downward E/W or N/S track and + is an all-direction track ramp that has the walls on one or two sides removed. Unfortunately this has a similar drawback as above: after a certain speed, the cart will fly off the track instead of going down the downward slope.

Edit: apparently that has pretty much the same effect as using regular slopes on both sides as noticed before:

_    _    _
  \ /  \ /

However, it doesn't work the same way going backwards. The intersection track method appears to slow and stop a cart moving left, causing it to accelerate to the right.

Anyways, have fun with non-Newtonian physics, who knows how long they'll last!

[DrKillPatient]

The one-way linear accelerator that you mentioned might be a decent alternative to rollers, when used to bounce a cart back in the opposite direction. Perhaps that, combined with the fact that the minecart will fly over a gap of a certain length eventually (if given time to accelerate), can be used to bounce a minecart back and forth until it reaches a desired speed, upon which it jumps a gap and is "released". If that's possible, it would make an excellent feature in places where machine power is unavailable.

[Di]

Sir, you truly deserve a medal for this discoveries.

As for this:

I tried, but it seems like you can't use this to derail carts uphill. I wanted to make a free energy cartlift.
If we come up with a way to release the carts from the perpetual motion machine, I wonder if they "charge up" enough energy to go uphill?

Spoiler: xmoffitt's pothole booster (click to show/hide)

As an unintended side-effect of my ramp research, allow me to introduce Pothole Boosters!  A Pothole Booster is just a down ramp followed by an up ramp.  However, due to an unintended truncation effects of the physics engine, a cart will often exit the pothole faster than it entered!
As a demonstration, here is a cyclotron that gets up to (and maintains forever) an average speed of about 600 millitiles/tick from a  single push (East from just under the door).   _{Warning, attempts to replicate may be hazardous to the health of your dwarves.}

or to be more exact, slight modification of it

Spoiler (click to show/hide)

Code: [Select]

  |
 ┏┓
 ▼ ▼
 ▼ ▼
 ┗┛
 |
 ▲
The '|' means straight rail not connected to the booster circuit.


will work.

[Triaxx2]

I've tried out a cart actuated goblin chopper. Basically one pressure plate is linked to the power for a cart roller on a short track that's five tiles long. One acceleration tile, one pressure plate activated by the cart, a second acceleration tile and a roller running the other way. This causes the cart to bounce back and forth until the power to the rollers is disengaged. Linking it to upright spikes or spears turns them into an automated ventilator.

Faster than a water repeater and more reliable, as long as you have power.

[QuantumMenace]

Checking again, the cart started by a roller will move up two z-levels and stop on the next ramp. If you put the roller on the ramp, you might only need a roller every 3 levels.

But I found a much better linear accelerator:

WWWWWWWWWWWWWWW
=LLLLLLLLLLLLLLLLLLLLLLLL=

Where W is a wall and L is a N/E curve track ramp (for example). The cart derails and lands on the track ramp, which accelerates it east even though the wall is to the north! This repeats until it's more than fast enough to launch items. I'm not certain if there's a maximum speed, but it did become fast enough to sometimes move 2 tiles in 1 tick.

[hjd_uk]

Awesome, a Dwarven Minecart LINAC. So this would make an awesome Shotgun barrel?

[Iosyn]

Checking again, the cart started by a roller will move up two z-levels and stop on the next ramp. If you put the roller on the ramp, you might only need a roller every 3 levels.

But I found a much better linear accelerator:

WWWWWWWWWWWWWWW
=LLLLLLLLLLLLLLLLLLLLLLLL=

Where W is a wall and L is a N/E curve track ramp (for example). The cart derails and lands on the track ramp, which accelerates it east even though the wall is to the north! This repeats until it's more than fast enough to launch items. I'm not certain if there's a maximum speed, but it did become fast enough to sometimes move 2 tiles in 1 tick.

I think you just boosted the efficiency of my railgun by about 200%.