21 Mobility
In this section, our goal is to extend "mobility" into structures and then make those structures mobile. In other words, instead of mounting things onto engines, we'll make functional structures fly directly.
1 Basic Mobility Structures
In the previous section, we explained the principles of mobility and provided the basic 10gt flying machine. From the 10gt flying machine, we can extract the following mobility structure:
The necessary structures are:
- Two opposing pistons, at least one being a sticky piston
- Two observers, each activating one piston
- Slime blocks for connection
To extend a functional structure into a flying machine, simply fill in these three necessary components.
Since functional structures almost always contain slime blocks (though occasionally they don't), prioritize using existing slime blocks. It's best not to introduce new ones.
Next, if the functional structure contains observer-piston structures, prioritize using the existing observers. That is, add pistons to positions where observers can activate them. It's best not to introduce new observers.
Finally, place the pistons. Be careful to avoid exceeding the push limit and ensure all structures can be connected and moved.
2 Examples
What follows is practice. This section can't really be broken down further—it's just practice makes perfect. Also, the principles above aren't set in stone. Some players prefer introducing new slime blocks or observers, which can actually make the whole machine cleaner and more elegant.
2.1 a) Several TNT Duplicators
Pictured: Halwei's landing correction bidirectional TNT duplicator
This TNT duplicator has reached 12b and cannot have any internal structure modified. It can only be mounted using a flying machine and cannot move directly.
Similar structures include the high-firepower bidirectional TNT duplicator shown in the figure.
For the simple TNT duplication structure shown, we can use the slime block directly facing the piston as the slime block mentioned in the third point above. That is, both the piston and observer connect to this position, as shown.
This way, we complete the other part with slime blocks and observers.
Now the simple TNT duplicator can move normally.
In practice, TNT duplicators mostly use ready-made structures, such as the bomber module from ilmango's world eater in the previous section.
2.2 b) Known Piston Structures
For the problem left from the previous section, we can arrange the piston structure like this—just move the pistons in sequence:
Due to unavoidable sticking issues, this is tricky for beginners to solve. Here we replace the floor with obsidian and set aside the floor sticking problem for now.
Compress the pistons. At this point, we need to make sure the lower part moves one block first, then the upper part moves one block, then the lower part moves again—this maps exactly to the two parts of the flying machine.
Connect the slime blocks and observers.
Next, complete the flying machine as follows:
As shown, we achieved reuse of slime blocks and observers in the upper structure. The lower part can't be connected due to distance.
Next, back up and test (even though the structure is simple and backup isn't that useful, it's still good to build the habit).
2.3 c) Other Structures
Structures vary wildly—there's really no unified standard to measure them by. So we won't go into detail from here on. Just try to satisfy the three points above.
Similarly, the various priorities aren't mandatory either. Heck, the engine doesn't even have to be 10gt. We just need to satisfy the principles of 1.2.1.
