Grid fin

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Grid fins (or lattice fins) are a type of flight control surface used on rockets and bombs, sometimes in place of more conventional control surfaces, such as planar fins. They were developed in the 1950s by a team led by Sergey Belotserkovskiy [ru]^[1] and used since the 1970s in various Soviet ballistic missile designs such as the SS-12 Scaleboard, SS-20 Saber, SS-21 Scarab, SS-23 Spider, and SS-25 Sickle, as well as the N-1 (the intended rocket for the Soviet moon program). In Russia, they are thus often referred to as Belotserkovskiy grid fins.

Grid fins have also been used on conventional missiles and bombs such as the Vympel R-77 air-to-air missile; the 3M-54 Klub (SS-N-27 Sizzler) family of cruise missiles; and the American Massive Ordnance Air Blast (MOAB) large-yield conventional bomb, and on specialized devices such as the Quick-MEDS delivery system and as part of the launch escape system for the Soyuz spacecraft.

In 2014, SpaceX tested grid fins on a first-stage demonstration test vehicle of its reusable Falcon 9 rocket,^[2] and on December 21, 2015 they were used during the high-velocity atmospheric portion of the reentry to help guide a commercial Falcon 9 first stage back to land for the first successful orbital booster landing in spaceflight history.

The 1st stage of the private Chinese company i-Space's Hyperbola-1 rocket appeared on July 25, 2019 to be equipped with steerable grid fins for attitude control.

On July 25, 2019, China launched a modified version of Long March 2C which featured grid fins atop the first stage for controlled re-entry of the spent rocket stage away from people in nearby towns and cities.^[3]