Grid fin


Grid fin

Grid fins (or lattice fins) are a type of flight control surface used on missiles and bombs in place of more conventional control surfaces, such as planar fins. They have been 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", SS-25 "Sickle", and the N-1 (the intended rocket for the Soviet moon program). In Russia, they are referred to as "Belotserkovskiy" grid fins [cite book |last=Zaloga |first=Steve |authorlink= |title="The Scud and Other Russian Ballistic Missile Vehicles" |year=2000 |publisher=Concord Publications Co |location=New Territories, Hong Kong |isbn=962-361-675-9 ] .

Grid fins have also been used on conventional missiles and bombs such as the Vympel R-77 air-to-air missile; the SS-N-27 ("Klub") family of cruise missiles; and the American Massive Ordnance Air Blast (MOAB) large-yield conventional bomb. They have also been used on specialized devices such as the Quick-MEDS delivery system and as emergency air brakes on the Soyuz TM-22 spacecraft.

Design characteristics

Conventional "planar" control fins are shaped like miniature wings. By contrast, grid fins are a lattice of smaller aerodynamic surfaces arranged within a box. Their appearance has sometimes led them to be compared to potato mashers or waffle irons.

Grid fins can be folded against the body of a missile more easily than planar fins, allowing for more compact storage of the weapon; this is of importance for craft which store weapons in internal bays, such as stealth aircraft. Shortly after release, the fins are swiveled into place for use as control surfaces. In the case of the MOAB, grid fins allow the weapon to fit inside a C-130 cargo bay for deployment while the craft is in flight.

Grid fins have a much shorter "chord" (the distance between leading and trailing edge of the surface) than planar fins, as they are effectively a group of short fins mounted parallel to one another. Their reduced chord reduces the amount of torque exerted on the steering mechanism by high-speed airflow, allowing for the use of smaller fin actuators, and a smaller tail assembly overall. Their small chord also makes them less prone to stall at high angles of attack, allowing for tighter turns.

Grid fins perform very well at subsonic and supersonic speeds, but poorly at transonic speeds; the flow causes a normal shockwave to form within the lattice, causing much of the airflow to pass completely around the fin instead of through it and generating significant wave drag. However, at high Mach numbers, grid fins flow fully supersonic and can provide lower drag and greater maneuverability than planar fins.

Notes

References

* [http://www.aerospaceweb.org/question/weapons/q0261.shtml Missile Grid Fins, "Aerospaceweb.org"]
* [http://www.dtic.mil/ttcp/wpn.htm Conventional Weapons Technology Group, "Defense Technical Information Center"]
* [http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/03173news.xml "It's the Big One", "Aviation Week"]
* [http://www.bharat-rakshak.com/NAVY/Klub.html KLUB (SS-N-27) ASCM, "Bharat-Rakshak.com"]
* [http://www.afrlhorizons.com/Briefs/Jun02/MN0206.html Small Smart Bomb with Range Extension, "Air Force Research Laboratory"]
* [http://www.defensetech.org/archives/001044.html Medical Missile Prepped for Launch, "DefenseTech.org"]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Fin — but has been extended to include other animal limbs and man made devices.The foremost use of fins is to ensure the directional stability of an object moving through a fluid such as water or air and may be seen in the use of fletching on arrows… …   Wikipedia

  • Grid Computing — Grille informatique Pour les articles homonymes, voir Grille …   Wikipédia en Français

  • Grid computing — Grille informatique Pour les articles homonymes, voir Grille …   Wikipédia en Français

  • World Community Grid — Traduction à relire World Community Grid → …   Wikipédia en Français

  • Smart grid — Schéma théorique d un réseau d interconnexion entre l Europe, l Afrique du nord et le Moyen orient La smart grid est une des dénominations d un réseau de distribution d électricité « intelligent » qui utilise des technologies… …   Wikipédia en Français

  • North Sea Offshore Grid — The North Sea Offshore Grid, officially the North Seas Countries Offshore Grid Initiative (NSCOGI), is a collaboration between EU member states and Norway to create an integrated offshore energy grid which links wind farms and other renewable… …   Wikipedia

  • Ball Grid Array — Saltar a navegación, búsqueda Las conexiones Ball Grid Array son soldaduras cuyo fin es unir un componente a la placa base de un equipo informático por medio de una serie de bolitas de estaño. Son usadas comúnmente en la producción y fijación de… …   Wikipedia Español

  • Smart grid — Se ha sugerido que este artículo o sección sea fusionado en Red eléctrica inteligente (discusión). Una vez que hayas realizado la fusión de artículos, pide la fusión de historiales aquí. Smart grid es un término inglés que puede traducirse por… …   Wikipedia Español

  • Voiture électrique — Une voiture électrique est une automobile mue par la force électromotrice de moteurs électriques, alimentée soit par une batterie d accumulateurs, soit par une pile à combustible (hydrogène ou méthanol), soit par un moteur thermique générateur… …   Wikipédia en Français

  • Proyecto EUFORIA — Saltar a navegación, búsqueda EUFORIA (EU Fusion fOR Iter Applications) es un proyecto financiado por la Unión Europea a través del Séptimo Programa Marco (FP7) que proporcionará un marco de referencia amplio y una infraestructura completa y… …   Wikipedia Español