Fowler
Good questions!
Zoom climb. We might say that there are three ways an aircraft gains altitude. One might be while performing a climbing maneuver such as a Loop or Immelmann...in these maneuvers, the pilot is pulling G. This positive G results in a flight path that "curves" up.
A second type of climb is the "normal" climb where the pilot raises the nose, adds climb power, and then adjusts his pitch attitude to maintain a predetermined climb speed. This climb speed will get the pilot the most altitude gained over an extended period of time. In AH, this speed varies between 160-200mph or so, depending on aircraft type. The normal climb is done at a constant speed. As the aircraft gains altitude, its climb performance decreases...the pilot must lower his pitch attitude to prevent his speed from falling off. This results in a gently curving flight path that "curves" down as the climb progresses. Normal climbs are done at one G (actually, in a wings level climb, the G load is mathematically slightly greater than one...but who cares!!)
The third type can be called the "zoom climb". Here, the pilot is attempting to exchange speed for altitude at a greater than normal rate. The objective is to reach a higher altitude at the expense of speed. At the end of the "zoom", the pilot will typically be at a relatively low speed, perhaps as low as zero mph.
The "zoom climb" is best done at low G...zero G if able...this will minimize drag and extend the climb to the maximum. This will also result in a relatively straight flight path. The pitch attitude will be determined by where the pilot wants his aircraft to end up. This implies that the "zoom climb" is performed for a specific reason and against a specific target. If all the pilot wanted was to gain altitude without respect to a target, then the "normal" climb would probably be more appropriate.
Zoom climbs are often seen in "boom and zoom" tactics and as a defensive response in some situations. In any case, the pilot must be assured that his eventual position at the top of the zoom will keep him out of danger, since his end game speed will be too low to allow much in the way of aggressive maneuvering.
Snapshots. There are two kinds of gun attacks. One type is known as a "tracking shot". In this attack, the pilot is turning in the plane of motion of the target and is holding his gunsight aiming reference on a constant aiming point. The objective is to have the rounds fired hitting the target as it moves through the sky. If the aiming point is correct, the projectile stream will follow and hit the target as it moves.
Sometimes, an attacking pilot is unable or unwilling to maneuver in the target's plane of motion...but he still wants to make a firing pass.
To accomplish this, all the pilot has to do is compute an intersection between the target's future position and the rounds fired. The pilot will then fire a burst at that point with the expectation that the target will fly through the projectile stream. This is truly a "hit or miss" situation, and that is why snapshots are known as low probabiliity of kill (Pk) attacks.
In the snapshot, the pilot is not attempting to fly his gunsight aiming reference in the target's plane of motion. Instead, he is trying to fly that aiming reference to a point in front of the target (and in the target's plane of motion).
Snapshots usually occur in high angle off situations. These may be planned or accidental. The primary reason for a planned snapshot is that the attacker wants to reposition or separate and not tie himself to the target. The primary reason for an accidental (unplanned) is when a firing opportunity presents itself, often during a muti-bogey, turning "knife fight".
You can find an academic discussion of the gun attack in SimHQ's Air Combat Corner.
http://www.simhq.com/simhq3/sims/air_combat/air_combat.shtml