For a long time, I wanted to build a flying machine that was more compact and expandable than the standard piston-slimeblock version. I discovered that, by combining a teleport command block, a clone command block, and a fast redstone clock, I could create an aircraft that was simpler, more compact, and easy to expand. This instructable will cover how to build the most basic version of the command block aircraft.

Step 1: Build the Frame

The first step in building the flying machine is to build the frame. The simplest frame is a 7x3 rectangle, with a hole cut out of the middle 3 and 4 blocks from the front, and the back-left corner and back-middle removed. In this image I have also added a shulker box for storage and some stairs to make it easier to mount.

If this is your first time building the command block aircraft, I strongly recommend building it so that the front faces towards negative Z. Doing so will allow you to copy and paste the commands in step 3 without having to change them. You can determine what direction you are facing by pressing F3.

Step 2: Wire the Clock

Once you have a frame, the next step is to build the redstone clock. The picture above shows how to lay it out. Do not forget to place a redstone-conductive block at the upper-right corner where the repeaters are diagonally adjacent; in this instructable I have used red concrete to make it easy to see.

You may have noticed that the clock is not entirely complete. The gaps are important, as in the next step command blocks will be added to them.

Step 3: Add the Command Blocks

After the clock is set up, the third step is to add command blocks. The command blocks must be set up in a very specific way. Each command block used in the aircraft is listed below, along with its settings, location, and an overview of its purpose. The numbers in the image above correspond to the listing below. You may have to temporarily destroy parts of the frame to position the blocks correctly.

setblock ~2 ~1 ~-6 minecraft:redstone_block
Impulse, Unconditional, Needs Redstone
Facing towards positive X
This command block is used to start the aircraft, together with #2. It places a redstone block at the corner of the clock, providing an initial impulse to the clock.
setblock ~1 ~1 ~-6 minecraft:redstone_wire
Chain, Unconditional, Always Active
Facing towards positive X
This command block is used to start the clock, together with #1. It replaces the redstone block with redstone dust, completing the circuit.
setblock ~ ~-1 ~-5 air
Impulse, Unconditional, Needs Redstone
Facing up
This command block stops the aircraft. It destroys a piece of redstone dust, breaking the circuit.
tp @e[r=3] ~ ~ ~-3
Impulse, Unconditional, Needs Redstone
Facing towards negative Z
This command block moves the aircraft, together with #5. It teleports all entities on the aircraft forward, moving them along with the aircraft.
clone ~-1 ~ ~-4 ~1 ~2 ~4 ~-1 ~ ~-7 replace move
Chain, Unconditional, Always Active
Facing towards negative Z
This command block moves the aircraft, together with #4. It clones the aircraft itself and moves it forward.
setblock ~1 ~ ~ lever 14
Impulse, Unconditional, Needs Redstone
Facing towards positive Z
This command block triggers #4 and #5, together with #7. It places a powered lever on top of #4, providing power.
setblock ~1 ~ ~-1 air
Chain, Unconditional, Always Active
Facing towards positive Z
This command block triggers #4 and #5, together with #6. It destroys the lever placed by #6, making an impulse of power rather than constant power.

Step 4: Finish the Redstone Wiring

The aircraft is almost done. There are only a few more blocks to place!

Place two solid blocks at the back of the aircraft, one over the right corner and the other covering command block 2, then place a lever on the side of the second block so that it is over command block 1.

Place a button on the side of command block 3 by shift-right-clicking.

Place redstone dust on top of command blocks 6 and 7.

Step 5: Decorate

The aircraft is now ready to fly, but who would fly without a little decoration? The aircraft actually moves its full 7x3x3 space, so take advantage of that and decorate a little!

Step 6: Fly!

The aircraft is ready to fly! Throw the lever to start it moving and press the button to stop it.

This design is easily expandable. I encourage you to play around with the command blocks, particularly the bounds of clone.

There are plenty of other ways to expand on this design. For example, if you link four together, each facing a different direction, you can create a fully controllable flying machine that can move in any direction.

Enjoy!