For better or for worse, sooner or later, Navy air will be upset by unmanned systems. To begin this transition sooner and in a better fashion, the pivotal need is an automated recovery system aboard surface ships to permit operation of high-performance, fixed-wing unmanned aerial vehicles (UAVs). These vehicles would have payload bays suitable for modular mission payloads that could be interchanged on board ship.
Current Navy UAV efforts seem to be concentrating on vertical take-off and landing (VTOL) systems. Over the years, the Navy has pursued VTOL unsuccessfully, investing untold millions of man-hours and dollars either on its own or in conjunction with the Army and Air Force. Some concepts worked, but they were not pursued and deployed in the fleet for a variety of reasons: short range, small payload, low speed, high risk to the pilot and ship, high maintenance, special pilot skills required, weather sensitivity, short life, high initial cost, high operating cost, noise, complexity, or low growth potential. The real question is, is there a better solution than VTOL?
As carrier aircraft became heavier and faster, the Navy turned to such solutions as the steam catapult, angled deck, and sophisticated arresting and approach systems. It did not seriously modify the aircraft, thus sacrificing performance, or go to VTOL. It modified the carrier. In the case of the UAV, the Navy should consider a similar philosophy—put take-off and landing aids on the ship rather than in every air vehicle.
Short Stop
The "Short Stop" UAV recovery-and-launch system proposed here would provide automatic operations from surface ships in high sea states, day or night, in adverse weather, with the ship stopped or under way. It will handle high-performance vehicles in a range of gross weights up to about 10,000 pounds. It is adaptable to both frigates and destroyers, and because the system is automatic, no highly developed piloting skills are required.
The major element of this system is a beam extended from the side of the ship during operations, supported by articulated arms, fore and aft. It can be retracted into or folded against the hull when not in use. During recovery operations, the beam is stabilized in inertial space to compensate for ship roll, pitch, and heave.
Using the Global Positioning System, the operator would guide the UAV to the ship, where it would acquire the homing target on the recovery platform and be brought automatically into the recovery approach path to the platform.
The platform, mounted on the beam, can move along the beam. It includes a shock absorbing surface that also restrains the vehicle during deceleration. The recovery window is large enough to accommodate residual vertical and horizontal homing errors. When the vehicle tailhook engages the arresting wire, the wire extends, releasing the platform and shutting down the engine. The platform motion is restrained by a wire in the beam attached to a braked reel. The vehicle is brought to a controlled stop.
Various methods of launch can be used: catapult on the ship, catapult on the beam, or an expendable rocket-assisted take-off bottle to accelerate the vehicle along the beam.
A major benefit of this system is that it does not endanger the ship or her personnel. The Short Stop system keeps the UAV line of flight clear of the ship for both recovery and launch. This is not true of VTOL UAVs operating toward and over the ship.
Related Issues
Controllers. Rated pilots are not required for Navy UAV operations. Midcourse control of Tomahawk (a one-way Navy UAV) during extensive development flight tests was accomplished without pilots by using simple autopilot commands: climb, descend, turn right or left, speed up or slow down. If the Navy uses a catapult launch and Short Stop automatic recovery, it would eliminate the need for piloting skills. If the Navy uses VTOL vehicles, however, skilled pilots might be needed for the take-off and landing stages of the mission. The use of enlisted personnel and warrant officers as controllers will minimize retention problems experienced with rated pilots in aircraft.
UAV Design. A major feature of the UAV is the central payload bay, which can be used for auxiliary fuel or a variety of payloads. The commodious bay can be configured aboard ship to suit the mission, or multiple missions, including attack, surveillance, antisubmarine warfare, target designation, data relay, electronic countermeasures, damage assessment, support of Marines ashore, exercises, and launch of multiple weapons. However, some platforms may be assigned fixed payloads, i.e., the sophisticated radar necessary for early warning patrol. The central bay also simplifies the autopilot software problem.
Several small, fuel-efficient turbo-fan engines are available. Operation to Mach .85 is desirable. Special features include a retractable tailhook and hold-down talons. The lower body surface can be reinforced. The wings and tails can be folded manually for handling and stowage.
The cost and complexity of redundancy or other heroic reliability enhancements might not be warranted. We must be able to lose some of these UAVs and not have it be a national disaster. Good conventional-winged UAVs can be designed and built rapidly and inexpensively by numerous competitive suppliers.
An Air-Capable Ship. An air-capable UAV ship's main mission should be to fly and to support UAVs. It might deploy with another ship of about equal size that would provide helicopter support and surface, subsurface, and air protection.
The first air-capable ships for high-performance UAVs probably will be modified current designs, such as the Arleigh Burke (DDG-51)-class guided-missile destroyers. Their UAVs would be in the medium weight category. Eventually, a fully air-capable ship, such as a version of the DDX, will evolve. With an integrated high-capability Short Stop system, electromagnetic catapults on deck or in the beam would launch high performance UAVs weighing up to 10,000 pounds. A large hangar space would service and store 30-40 vehicles in sealed, temperature- and humidity-controlled, multilevel compartments. Elevators would take UAVs from the hangar deck to the flight deck. Finally, the ship would need a series of magazines to store interchangeable payload packages, sizeable storage for UAV fuel, and mission planning facilities and personnel.
Mr. Lynch is an independent engineering consultant. He was the chief engineer for Tomahawk at General Dynamics during design, development, and production.