Ballistic trajectory in the context of "Escape velocity"

A rocket (from Italian: rocchetto, lit. ''bobbin/spool'', and so named for its shape) is an elongated flying vehicle that uses a rocket engine to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Unlike jet engines, rockets are fuelled entirely by propellant which they carry, without the need for oxygen from air; consequently a rocket can fly in the vacuum of space. Rockets suffer deceleration by atmospheric drag in air, and operate more efficiently outside the atmosphere.

Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets may use momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, and spin, or may simply fly in a ballistic trajectory under the influence of gravity.

A sling is a projectile weapon typically used to hand-throw a blunt projectile such as a stone, clay, or lead "sling-bullet". It is also known as the shepherd's sling or slingshot (in British English, although elsewhere it means something else). Someone who specializes in using slings is called a slinger.

A sling has a small cradle or pouch in the middle of two retention cords, where a projectile is placed. There is a loop on the end of one side of the retention cords. Depending on the design of the sling, either the middle finger or the wrist is placed through a loop on the end of one cord, and a tab at the end of the other cord is placed between the thumb and forefinger. The sling is swung in an arc, and the tab released at a precise moment. This action releases the projectile to fly inertially and ballistically towards the target. By its double-pendulum kinetics, the sling enables stones (or spears) to be thrown much further than they could be by hand alone.

Non-ballistic atmospheric entry is a class of atmospheric entry trajectories that follow a non-ballistic trajectory by employing aerodynamic lift in the high upper atmosphere. It includes trajectories such as skip and glide.

Skip is a flight trajectory where the spacecraft goes in and out the atmosphere. Glide is a flight trajectory where the spacecraft stays in the atmosphere for a sustained flight period of time. In most examples, a skip reentry roughly doubles the range of suborbital spaceplanes and reentry vehicles over the purely ballistic trajectory. In others, a series of skips allows the range to be further extended.

Direct fire or line-of-sight fire refers to shooting of a ranged weapon whose projectile/ordnance is launched directly at a target within the line-of-sight of the user. Direct fire weapons typically have a sighting device to ensure accuracy and must have an unobstructed view to the target with no obstacles or friendly units in between, meaning that they can only effectively engage targets that are in enfilade. Conversely, direct fire units are also directly exposed to return fire from the target unless they are shooting from a position of defilade or concealment.

Direct fire is in contrast to indirect fire, which refers to firing a projectile on a curved ballistic trajectory or delivering self-accelerated munitions capable of long range and various degrees of homing abilities to alter the flight path. Indirect fire does not need a direct line-of-sight to the target because the shots are normally directed by a forward observer who provides the coordinates and calibrations needed to hit the target. As such, indirect-fire weapons can shoot over obstacles or friendly units and the weapons can be concealed from counter-battery fire.

Indirect fire is shooting a projectile without relying on a direct line of sight between the gun and its target, in contrast to the case of direct fire. Aiming of indirect fire is instead performed by predicting a parabolic ballistic trajectory via calculation of the azimuth and inclination, and may include calibrating the aim by observer feedback about the actual point of impact of the preceding shot and thus readjusting to new firing angles for subsequent shots.

Indirect fire is the principal method of long-range artillery fire support, both from land and naval platforms. Due to the projectile's longer flight time (which exposes it more to deflectional factors such as drag and crosswind), curved trajectory, and the far and often obstacled "beyond-visual-range" nature of the targets, indirect fires are inherently harder to aim accurately than direct fires, resulting in a more unpredictable external ballistics and thus a much more scattered shot grouping. This, coupled with the significant blast distance of the explosive ordnance and their shrapnels, translates to a much higher risk of collateral damages and friendly fires, especially when firing danger-close.