Tutorial:TNT cannons/Mid-air maneuvering

Mid-air direction changes are mostly achieved using Injectors.

All of the cannons in this section have the advantage that they can be build to Shift freely around the enemy with often very small barrels.

Down (D<damage type>)

A Downwards cannon hits the enemy from above.

The hopes here are, that the enemy might have less armor or shielding there. This isn't the case very often. But Downwards cannons also have the efficiency provided by Mortars.

Up (U<damage type>)

An Upward cannon hits the enemy from below.

Oftentimes the ground or water prevent the usage of Upward cannons. But if they can be used they usually also hit the most vulnerable part of the enemy. This is due to the advantages of Nether cannons compared to other Buffer cannons and the advantages of Ascending- compared to Descending cannons. The use of Upward cannons is mostly limited to scraping the enemy from below since for full penetrations the Downward cannons are more efficient.

Flank (F<damage type>)

Flanks hit the enemy from their side.

The main use of Flanks is speculation for double kills. The idea behind that is that Formations tend to be symmetric... For this reason in metas, where Flanks are generally as strong as or even stronger than front Tunnlers asymmetric Formations are greatly encouraged. In metas where Flanks are weaker also less shielding is to be expected so in that case one would only use them to punish the enemies negligence when it comes to that.

Back (B<damage type>)

A Back cannon hits the enemy's rear.

Often enemies disregard protecting their back side. A Back cannon's only common purpose is to exploit this missing armor and shielding. Apart from that, it is generally weaker than the other types because the enemy blocks its ideal flight path and so it uses weird diagonal up to orthogonal angles or is forced to have an extra redirection phase (every time TNT is redirected in mid-air the accuracy decreases by a lot and this starts to become quite severe for the efficiency of many Back cannons).

Warhead (W)

Warheads change direction inside the enemy.

In essence Warheads are just worse Flanks or Downward cannons because they first need to dig inside the enemy. Sometimes they can be useful because the middle is better protected than the sides, or enemies put their cannons very close to each other and so Warheads can kill the other with almost no effort.

Delayed fire

Automatics tend to be among the first cannons targeted and so it is advantageous to let them be done with their job by the activation of TNT damage. To get rid of any TNT at the launch point the projectiles and Injectors are boosted forward at low velocity. This technique also finds use for better far shifts but generally Multiple impact cannons do the same job in better (since each shot penetrates the enemy only partially they also can use slower velocities and thus are slow enough for all shots to escape in time).

Gust

A Gust is a front cannon that changes direction outside the fight machine for the purpose of smaller barrels or further shifting.

It suffers the same problems as a Back cannon but at the front there are no armor/shielding gaps to compensate.

Momentum cancelling

Blocks that cancel entity momentum (such as powder snow) can be used to change the direction of TNT in mid-air but that is not advisable except for chunk phasing cannon applications since this technique applies after one processing of the TNT and so higher delays - the most important step for efficient cannons is not possible here. Apart from that the technique is quite precise.

Implementation techniques

When the charges are traveling at speeds below eight blocks per tick, the propellants will accelerate each other. That should be taken into account when trying to find the optimal position for them relative to the projectiles.

It might be optimal to have the projectiles travel slightly in front (or more rarely behind) the propellants. The first reason for such variations is that the propellants usually explode before the propellants tick. This means that the first few propellants will be in front of the projectiles until they got slowed down enough. The second reason is that the prior momentum of the projectiles needs to be cancelled so some of the propellants need to explode in front of them. Usually the propellants exploding first resolves this though.

Another factor is that often the prior momentum of the projectiles needs to be cancelled. For this reason and propellants usually exploding before the projectiles tick it might be optimal to have the projectiles travel slightly in front (or more rarely in the back).

Having more direction changes often results in lower accuracy and/or efficiency. While for the first phase it might be fine to have an angle of more than a degree between propellant and projectile before they are launched, for the second phase precision below a degree difference might be needed as one degree over 100 blocks already equates to almost 2 blocks difference. In Backsteps you could use a difference of about 0-degrees so that the only difference is in distance to the booster. This difference in distance translates to slower/faster speed and is usually way less sensitive to change than to differences in angle: One pixel orthogonal difference over two blocks results in 3 blocks difference at 100 blocks distance while one pixel collinear difference over two blocks results in just one block difference.

Another technique that has use in certain situations is accelerating projectile and propellant while they have different velocities. This finds use when both should get the exact same acceleration for example for aiming using TNT shift or it can reduce/increase how far apart the TNT are compared to each other, even potentially flipping their relative positions as is done in one of the example cannons.

Orthogonal

In most cases it is recommended to use the orthogonal technique due to its increased consistency when shifting. The name refers to the vector from propellant to injector being almost orthogonal to the vector from the boosters' explosion center to the propellants/injectors. If the cannon is shifting, it also needs to be orthogonal to the vector(s) between the different booster positions. In some cases this can only be done by using the null vector (or any vector of very small magnitude) and relying on a difference in velocity as discussed above.

Aligned

The aligned technique can be easier to implement when changing to a vertical direction and in few cases even preferred but is generally worse because of the reduced consistency when shifting. The name refers to the vector from the injectors to the propellants being almost collinear (or aligned, if both point in the same direction) to the vector from the boosters' explosion center to the propellants/ injectors.

Example setups

The example setups can be generalized to shoot at any speed in any direction.

Slanted shot orthogonal Downstep

This cannon shoots diagonally above the target and then down to hit it.

A vertical difference in position of projectile and injector are used in combination with a difference in speed due to the projectile already falling for some amount of ticks before being launched to achieve that. While the projectiles get a bit more upward acceleration from the boosters this is not enough to overcome the speed difference and thus they end up below them.

The cannon uses five boosters, three injectors ignited ≈18 redstone ticks after the boosters and a low amount of projectiles. The piston pushing the projectiles over the propellants is activated 73 game ticks after the boosters are ignited.

Slanted shot aligned Downstep

This cannon shoots diagonally above the target and then down to hit it.

It only uses a horizontal difference in position of projectile and injector. Because aligned technique is used instead of the orthogonal the angle PBI (projectiles, boosters' explosion center, injectors) is way smaller than it would be if the orthogonal technique would be used. This makes it easier to build - it is the same as the other setup except that the piston timing is not needed. Similar setups are also easier to find. But this comes at the cost of the aligned technique discussed above. The setup can still provide a versatile cannon, that can sometimes hit the target from the top and scrape the back, front and sides of it while being harder to evade for moving targets due to the inconsistency of it. Where similar setups completely fail is at tunneling but in this specific case this is not a big problem as it can be used as a Down-Mortar.

Ejector Flanktunnler

This cannon first shoots sideward then more or less straight towards the target and then inward to hit it.

Immediately after the ejectors explode all other TNT rebound vertically and along the axis toward the target (note that for ascending/ descending the vertical rebounding is changed). Their relative positions stays almost the same, the distance between injectors and projectiles increasing slightly. This is the reason why this setup uses more precision to decrease the amount of distance between projectiles and injectors. From the first mid-air direction change on everything works as explained for the other cannons.

Four ejectors, eight boosters after ≈8 redstone ticks, variable amount of injectors after ≈18 redstone ticks and projectiles are used. Optionally one injector can also explode slightly before the others to increase damage consistency. Aligning the injectors using water is less practical than pushing them into a block with pistons and both achieve the same.

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