SPMA

Unreal Tournament 2004
The Self-Propelled Mobile Artillery (SPMA, often pronounced "Spamma" as opposed to letters only) is a wheeled vehicle, first seen in Unreal Tournament 2004 with the Editor's Choice Bonus Pack. It has two seats.

Pilot
Apart from driving the vehicle, the driver has access to the mortar shell cannon. Primary fire sends a single shell in the given angle. Alternate fire follows the shell, which can be deployed as a camera by pressing alternate fire again. Next, a target can be chosen by using the movement keys/buttons. Pressing alternate fire again will then send a set of five shells into the given area.

Gunner
The passenger controls a skymine turret akin to that of the Hellbender.

Uses
The SPMA is a powerful vehicle, capable of a wide variety of uses and accommodates many different tactics. In the hands of a good player, a SPMA can serve to either press a pre-emptive strike, or it can stave off an attacking force, all from a safe, indirect distance. In a pinch, the SPMA can also substitute for the Hellbender, and its skymine turret is just as effective as the Hellbender's, able to devastate infantry as well as quickly take out a node.

Offense
Offense is a bit of a balancing act: You can send the camera up high and be very hard to spot. (Especially on maps like ONS-IslandHop) However, your shell will fragment widely, which is fine if that's what the situation calls for. Conversely, a lower trajectory will allow you to much more greatly focus the shot, devastating more of a focused area; however, this also makes it easier to "trace the shell" and get a trajectory back to you, and you can be pretty sure if it's traced back, you'll be dealing with people in short order. Always keep an eye on your armor if you're bombarding - if it starts going down, you're getting shot at, and nothing's more annoying than to be focusing on bombing and you're suddenly dead.

Defense
Defending against the SPMA is generally not too hard. The hardest part will usually be actually finding the SPMA in the first place. If you find the camera, shoot it and attempt to watch as much of the surrounding area as possible, to see if you can find the next shell/camera as it's getting shot out. The shot always fires in a straight direction, in a parabolic arc, so if you see the shell flying for any appreciable length of time (at least half a second or so) you can generally figure out where the SPMA is. This is called "tracing the shell" or "shell tracing." Its strengths as a support vehicle means that other than that, it needs to be up close to do significant damage. (Note that, however, like the Hellbender, the Skymine Turret Detonator can be used like a slightly faster rate of fire shock rifle, although it does less damage.)

Vehicles that are excellent at taking out the SPMA are Raptors and Mantas, as it only has 600 armor, and will take it out relatively quickly, although the rapid, small amounts of damage risk tipping off the bombardier. If it's unmanned by a passenger, than you can even safely get reasonably close on foot and destroy it. (Flak and 3-Pack Rockets are excellent for this.) Be wary, however, some drivers will notice the damage and promptly switch to the second seat, so don't sit in a position where you can be easily skymined. Other equally good alternatives are the Cicada (Its rocket-queuing altfire mode will devastate and usually make quick work of a SPMA) or a Goliath (Two shots and it's dead no matter what.)

Unreal Tournament 3
"This self propelled mobile artillery (SPMA) device is infamous for its ability to blanket a large area with the devastating fire that falls from the sky above.  The Axon Hellfire is sufficiently maneuverable to deploy its long range artillery cannon on almost any terrain. A remote camera gives its operator a bird's-eye view of the battlefield through a targeting reticule that calculates the projected area of impact in real time.  The vehicle housing also incorporates a defensive shock cannon that deploys floating mines of unstable plasma which can be chain-ignited by the weapon's secondary fire photon beam."

- UT3 manual

Using the SPMA
In UT3 the SPMA needs to deploy to use its main turret and undeploy to use the skymine turret. Keep this in mind when looking for a place to attack from. The skymine turret is useful for defending against enemy players on foot or in open vehicles, like Manta or Viper, at close to medium range. When deployed, the main turret first fires a camera shell that, once it's underway, can be activated by pressing any of the fire buttons. Make sure you find a good place for the camera because placing a new camera is time-consuming. Keep in mind, that the camera can be taken down with a single hit. Also keep in mind that the camera shell is just as explosive as regular shells.

You should consider entering the SPMA only after picking up the AVRiL, so you can quickly get out and defend against flying vehicles.

Going against the SPMA
The best way to fight the SPMA is from high above it because that's one of the few places it can't reach directly. Any air vehicle should be fine as long as you either hover right above the SPMA or keep moving. If you don't move, the SPMA driver might actually try to pick you off with the main gun - shame on you if he succeeds! It's even more embarrassing to crash into a deployed SPMA camera shell, so watch where you're going.

If you don't happen to have a flying vehicle, a Manta, Scorpion or even the Link Gun are effective against a deployed Hellfire. Just make sure you catch the driver by surprise or attack from a place he can't reach. Some SPMA drivers resort to pretty desperate usage of the main gun by firing even the camera shell into walls or the ground next to an attacker and often enough even succeed.

From afar you can annoy the SPMA driver by making sure his camera won't stay up there very long. Take down any enemy camera shell you see. Even a single hit with an Enforcer is enough, but any precise weapons like Link Gun primary, Shock Rifle primary or the Sniper Rifle are effective with single shots.