1. Field of the Invention
This invention relates to adapting guidance systems to retrofit unguided rockets.
2. Description of the Related Art
Unguided ordnance cannot be steered toward a target and thus exhibit limited lethality. Unguided ordnance also pose considerable collateral damage concerns surrounding their use, particular in urban or “danger close” battlefield situations where friendly forces are in close proximity with enemy combatants. Such ordnance includes artillery and other tube-launched projectiles all of which will be referred to herein as “rockets”.
As shown in FIGS. 1a and 1b, an unguided 2.75″ Hydra-70 rocket 10 is one example of unguided ordnance. The Hydra-70 rocket includes propellant 12 inside a cylindrical airframe 14, a tail assembly 16 that includes a nozzle 18 and fins 20 that deploy to a fixed position upon clearing the launch tube, an explosive warhead 22 and a fuze 24 on the end of the warhead. The fuze includes an external thread form 26 that mates with the warhead's internal thread form 28 to form a threaded interface. Torque is applied to the fuze to drive a fuze lip 30 into the warhead to create an axial load to “preload” the fuze. When launched, the Hydra-70 rocket is spin-stabilized to fly unguided toward a target. Upon impact an initiation charge in fuze 24 transfers energy to the warhead to detonate a primary charge.
Laser, RF, infrared or Global Positioning System/Inertial Navigation System (GPS/INS) guided ordnance is commonly used to engage point targets with a high probability of success and minimal collateral damage. Such ordnance includes guided artillery and other tube-launched projectiles, all of which will be referred to herein as “missiles”. A laser guided missile typically includes a semi-active laser (SAL) seeker to detect laser radiation scattered from the intended target and to provide signals indicative of the target bearing to actuate aero-dynamic surfaces to guide the missile to the target. IR guided missiles sense the infrared radiation emitted from the target to guide the missile. A GPS/INS guided missile uses GPS updates of missile position, heading and velocity to guide the missile to mensurated coordinates programmed into the missile.
Guidance systems can be developed to retrofit unguided rockets to increase the lethality and decrease the collateral damage for the existing design and stores of unguided rockets. However, there are typically no external features present on the rockets to which the guidance systems can be attached in order to accomplish the retrofitting for “guided rockets”.