The US Patent and Trademark Office (USPTO) has granted Lockheed Martin Corporation a patent for a three-axis flap control system designed to vastly improve the steering of rocket-launched, hypersonic and supersonic re-entry vehicles and projectiles.
According to Lockheed Martin, the advanced design enables a single, simple, low-cost control system to steer re-entry vehicles in all three axes (pitch, yaw, and roll). The three-axis flap control system provides quick response and increased capability and controllability for difficult aerodynamic manoeuvres, as well as increased accuracy and weapon effectiveness.
‘This is a significant technological breakthrough,’ said Roger Teter, director of Fleet Ballistic Missile (FBM) Re-entry Systems at Lockheed Martin Space & Strategic Missiles and one of the three principal inventors of the system. ‘The three-axis flap control system represents a major step toward achieving low-cost, highly manoeuvrable re-entry vehicles for many different high priority precision strike military missions such as defeating hard and deeply buried targets.’
The control system employs four aft flush mounted movable flaps (or control surfaces) of uniform design, which decreases machining and manufacturing costs. The flaps are positioned on the vehicle orthogonally, but offset from the vehicle centreline. By actuating various combinations of flaps into the airstream, any desired vehicle orientation may be achieved. The flaps, which are all independently controlled, may be extended (deployed) from the stowed, non-deployed position to any desired deployed position, providing a variable control system for rocket-propelled projectiles and re-entry vehicles.
A demonstration of the flap control system was conducted in October 2002. A prototype three-axis flap control system was fabricated and integrated into a full-scale, fully instrumented Navy Mk 4 re-entry body and successfully flown from a Trident II D5 FBM during a routine operational test flight. The three-axis flap control system is said to have performed flawlessly during the mission and precisely navigated the re-entry body to the intended target. Further tests of the three-axis flap control system are planned for the near future.
In addition, the US Navy now intends to incorporate this new technology development into its Enhanced Effectiveness (E2) Demonstration Program, which will demonstrate a near-term capability to steer a Submarine Launched Ballistic Missile (SLBM) warhead from a Trident II D5 missile to Global Positioning Systems (GPS)-like accuracy. This program is scheduled to start in 2004.