Grid fin

Grid fins (especially in the Russian terminology referred to as grid fins) are a variant of control surfaces, which are used at various missiles and bombs instead of conventional rudder fins. They were first used around 1964 in the Soviet N1 moon rocket, and since the seventies as part of the design of Soviet ballistic missile, the cruise missile family SS-N -27 Sizzler or the GBU -43 / B MOAB. In the civil sector grid fins are, for example, as a stabilizer on the rescue system of the Soyuz spacecraft used.

Design features

Conventional planar control fin correspond miniaturized wings which are aligned in the direction of the missile longitudinal axis. In contrast, grid fins consist of many small areas that are located within a lattice-like transverse to the longitudinal axis box structure. Their appearance is reminiscent of a grating or a potato masher. The elongated box can thereby technologically simpler against the body of the missile fold than a conventional fin, which reduces the space required in the carrier system. This is especially advantageous for weapons to be carried, for example, by Stealth aircraft in internal weapons bay or launched from mobile launchers.

Aerodynamic properties

Grid fins have a far less tread depth than conventional control surfaces and can act as a group of parallel arranged smaller fins are considered. This reduces the restoring forces applied by the control mechanism, which allows the use of smaller actuators. The low tread depth also provides for a reduced susceptibility to stall at high angles of attack and allows control over planar surfaces a higher turn rate and thus maneuverability.

The aerodynamic efficiency and the flow resistance depends on grid fins heavily on the speed of the missile from: In the subsonic range and at higher Mach numbers, the flow is laminar through the grid and leads to reduced counter-forces and high rudder effect. However, there occurs in transonic velocities between Mach 0.8 and Mach 1.3 in the formation of shock waves within the lattice structure, which means that the air flow is guided around the fin, and a high flow resistance. Grid fins therefore are not suitable for missiles to cover a large part of their trajectory with transonic speeds.

Examples

Have benefited or grid fins for example, in the following missiles used to control:

  • Soviet SS -12 Scale Board / OTR -22 Temp
  • Soviet SS -20 Saber / RSD -10
  • Soviet SS -21 Scarab / 9K79 Tochka
  • Soviet SS -23 Spider / OTR -23 Oka
  • Russia SS -25 Sickle / RS -12M Topol
  • Russia AA -12 Adder / Wympel R -77
  • Russia SS-N -27 Sizzler / Klub
Soyuz TMA-6 Angle of attack RSD-10 Pioneer Steven Zaloga
266957
de