# Deflection (ballistics)

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{{Short description|Technique used for accurate shooting at a moving target}}
{{more citations needed|date=February 2023}}

'''Deflection shooting''' is a technique of [shooting](/source/shooting) ahead of a moving target, also known as '''leading the target''', so that the [projectile](/source/projectile) will "intercept" and collide with the target at a predicted point. This technique is necessary when the target will have significantly displaced its position during the time the projectile would take to reach the target, which can become the case [over very long distances](/source/long_range_shooting) (e.g. a long [sniper](/source/sniper) shot), due to fast moving targets (e.g. aerial [dogfight](/source/dogfight) against an opposing aircraft, or [anti-aircraft](/source/anti-aircraft) fire against passing aircraft), hunting a running animal,  or while using relatively slow projectiles (e.g. a [bolt](/source/crossbow_bolt) shot from a [crossbow](/source/crossbow), or a [basketball](/source/basketball_(ball)) thrown to a running teammate).<ref>{{Cite web |title=FIRE CONTROL FUNDAMENTALS - Part C |url=https://maritime.org/doc/firecontrol/partc.php |access-date=2023-02-02 |website=maritime.org}}</ref>

[Gyro gunsight](/source/Gyro_gunsight)s developed for aircraft of the [Second World War](/source/Second_World_War) displayed a [reticle](/source/reticle) that compensated for target lead. Modern [fighter aircraft](/source/fighter_aircraft) have automated deflection sights, where a computer calculates lead and projects the solution onto a [head-up display](/source/head-up_display) (HUD). The visual assistance with targeting the gun is offset by the speed and agility of modern aircraft, compared to the days when targeting was less advanced.

In [artillery](/source/artillery), deflection is also used against fixed targets to compensate for [windage](/source/windage) and range. Due to the [Earth's rotation](/source/Earth's_rotation), surface points have different velocities and curved motion, leading to apparent [Coriolis drift](/source/Coriolis_effect) of a long-range target.

==Computer games==
Modern computer games of the [first-person shooter](/source/first-person_shooter) genre typically feature a number of relatively low-velocity projectile weapons such as unguided [shoulder-fired missile](/source/shoulder-fired_missile)s, or fictional projectile weapons such as "plasma guns", which necessitates an attacker to lead his aim ahead of moving targets. Computer games that accurately model the ballistic trajectories (including velocity) of firearms also require leading of fire, much as in real life. This applies equally to combat aircraft (or even combat spacecraft) simulators, where the velocities of the craft involved are great enough to require leading with projectile weapons.

Additionally, in older [multiplayer video game](/source/multiplayer_video_game)s that calculate behavior on a remote server, even for high-velocity or [hitscan](/source/hitscan) weapons, there are issues of [latency](/source/Latency_(engineering)) that may require leading. Essentially, even if the shooter has the target exactly in their sights, by the time the information relating weapon fire from the shooter's computer has reached the [server](/source/Server_(computing)), the target may have moved enough to avoid the shot.
However, modern game-engines use a [lag compensation](/source/lag_compensation) system which moves all players back to a point in time based on the shooter's [client interpolation](/source/client_interpolation) time and [ping](/source/Ping_(networking_utility)) (or, alternatively, by trusting the result calculated entirely on the client side) to evaluate if there was a hit or not. Such systems eliminate the need to lead hitscan weapons, but introduce the risk of players being hit by enemy fire shortly after taking cover behind objects, due to the latency causing a delay before the victim's computer receives the message that he has been shot.

==References==
{{reflist}}

==See also==

* [Direct fire](/source/Direct_fire)
* [Artillery](/source/Artillery)
* [Auxiliary predictor](/source/Director_(military))

Category:Targeting (warfare)
Category:Military tactics
Category:Ballistics

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Adapted from the Wikipedia article [Deflection (ballistics)](https://en.wikipedia.org/wiki/Deflection_(ballistics)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Deflection_(ballistics)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.