With the rebirth of the Navy blimp, it is appropriate to examine how it can augment potential future missions, particularly of ASW forces. History suggests a synergism between the capabilities of blimps and submarine operations. The importance of modern submarines in the Maritime Strategy suggests that now might be the time to revisit this relationship to determine if former practices have modern application in submarine warfare.
This past June, the u.s. Navy awarded the first contract since World War II to build a prototype lighter-than-air airship. A $168.9 million contract to construct a battle blimp outfitted with a large internal radar equivalent to that carried by the E-2C HAWKEYE has been awarded to Westinghouse and the British Airship Industries. If the prototype passes tests demonstrating its ability to serve as an effective airborne early warning (AEW) system, it will likely lead to the wide-spread re-introduction of the airship into the fleet.
With the re-birth of the airship (blimp), it is time for the underwater warfare community to examine how blimps can 1.) furnish surveillance for SSN operations; 2.) facilitate communications for submarines and 3.) operate offboard sensors of use to submerged submarines.
During the course of WW II, Goodyear furnished the u.s. Navy with a fleet of some 165 non-rigid airships. These blimps formed 14 squadrons, made more than 40,000 patrols and escorted over 89,000 ships in convoys throughout the world, The U.S. Navy claims that not one single ship was lost while under airship protection. There was, however, one airship, the K-74, shot down by a German submarine.
Throughout the 1950’s the U.S. Navy utilized airships for anti-submarine operations and as an early warning system for incoming Soviet bombers. But the introduction of newer more sophisticated land based anti-submarine warfare airplanes resulted in the disbanding of the last of the Navy’s airship units in the early 1960’s.
ADVANTAGES IN AIRSHIP-SUBMARINE OPERATIONS
The use or airships offers some key advantages for operational missions with submarines. Although fixed wing aircraft and helicopters are faster, neither can match the lighter-than-air airship’s ability to stay airborne without refueling and maintenance. Also, estimates as to operating costs per hour reveal that a patrol plane is approximately five times as expensive in operations as the new blimp with its 11 day’s endurance at cruising speed.
Missions requiring long endurance on station, such as monitoring sonobuoy fields, providing a communication relay for submarines, and surveilling key chokepoints may best be performed by an airship.
Airships can carry much greater disposable loads than aircraft. Larger quantities of sonobuoys, sensors and supplies can be handled by lighter-than-air vehicles with much more space available for equipment in an airship than in a fixed wing aircraft. Large radar scanners used for AEW can be installed within the blimp’s bag, making better use of space.
There is the misconception that airships are easy to destroy. Modern airships use inert-gas helium which is a natural fire extinguisher. The gas pressure inside the envelope of an airship is usually only 0.5 to 1% above atmospheric pressure, so the leakage through bullet hole openings should be very slow. In the event of being hit by gun fire the airship would have a much better chance of returning to base with its crew and equipment intact, than would a fixed wing aircraft or helicopter. It would also be much easier to repair. Moreover, it is doubtful that a hit on an airship’s envelope with an impact or proximity-fused missile head would be sufficient to detonate the weapon.
It is also conjectured that the airship’s massive size results in a large blip on a radar screen. Airships, however, would have little metal and would incorporate some of the same radar absorbing materials as used in stealth fixed wing aircraft. The new Navy blimp will be constructed of composites with all reflective components protected by radar absorbing materials. Since the airship’s lift is obtained by its buoyant gas with little engine power needed for movement, airship engines produce a much lower infrared (IR) signature than do fixed wing aircraft and helicopters. If under attack, an airship, unlike other aircraft, can shut down its engines, thereby removing almost all traces of its IR signature.
The Navy’s born-again blimp can fly at ~0 knots and at 5,000 feet for up to 72 hours without refueling. Mounted in the airship’s 354-ft. envelope, away from atmospheric interference and protected by a clean inert gas environment, it will be able to provide surveillance against seaskimming missiles for a radius of at least 200 miles. It can also prove useful by delivering and monitoring sonobuoys, as well as towing an acoustic array.
But importantly, for submarines, an airship can be a remotely operated drone to augment submarine and particularly combined operations.
The U.S. Navy has funded two conceptual studies of high altitude drone airships. One unmanned vehicle would be able to hover in one location at an altitude of 70,000 ft. for periods up to 100 days. Its 500 ft. nonrigid airship design would carry 5 million cubic feet helium of Intended military missions include air/sea surveillance, communications relay, and sensor readout.
In the past, airships have been traditionally cigar shaped, but today’s technology is coming up with revolutionary designs providing greater performance characteristics for certain missions.
The principle advantages of airships complement the tactical flexibility of submarine operations. Their long endurance and high payload provide the ability to extend detection ranges. The submarine can be provided with extended early warning of approaching surface threat forces on a real time basis, and groups of submarines can be positioned to meet enemy forces in a manner similar to the wolf-pack tactics of WW II.
The long on-station time of airships allow for barrier tactics in the vicinity of choke points similar to that currently employed by submarine forces. Airships operating together can extend these barriers over significant ocean distances. Sonobuoy fields laid by the airship and to be read-out by submarines could be maintained for long periods of time, replenished as needed, and repositioned as the threat changes.
An added feature inherent in airship design, that of low speed maneuverability, provides a possible expansion of sensor employment to a towed array or remotely controlled undersea vehicle. This would require submarine operations nearer the ocean surface, but is particularly effective in that the sensor employment platform is not in the water. Figure 1 illustrates this employment mode.
The use of sensors in this fashion with a tethered connection to the monitoring blimp provides real time data collection and a greater range of sensor employment for the submerged vehicle. Again towed devices could be used in coordinated operations to extend the area of surveillance and increase the quality of information by providing multisensor aspects.
The combination of passive sensors and a tethered connection to a platform which is not in the water would provide little warning to enemy submarine forces that surveillance devices were in the area. Rapid processing of this information, optimization of counter force positioning and reliable dissemination to friendly submarines would enhance ASW effectiveness.
COMMUNICATIONS WITH SUBMARINES
The ability to reliably communicate with friendly forces is the key to this type of operation.
Historically the submarine has been cast in roles which do not require extensive communication with other forces. The tactical advantages attained through stealth and covertness typically outweigh the risk of exposure through communications. None-the-less, there are periodic needs during submarine operations for communications with other naval forces. The introduction of airships would not alter communication techniques for the submarine, but they would furnish a platform which can enhance the quality and quantity or information available to the submarine through current methods. The receipt of information is least dangerous to the submarine since it does not require it to send active transmissions and it oan be accomplished on an area broadcast basis without revealing the presence of the submarine in a particular location. From its patrol station the airship can broadcast information from the shore or received from its own deployed sensors to merely the general area of submarine operations. Figure 2 illustrates some general communications methods.
In its capacity as an airborne command post, the airship replicates the communications role of a satellite. It has the advantages of not requiring the substantial space program resources — being able to remain on station, eliminating the threat of antisatellite weaponry, and providing other capabilities beyond mere communications.
Airship personnel on the scene can provide tactical support to multiple submarine operations. The benefits derived from obtaining information through the airship’s multi-sensors, however, should enable the massing of undersea forces at optimum locations. This would outweigh the temporary constraints for many scenarios. Once the submarine is directed to an attack position it is free to break communications until mission completion.
It is apparent that lighter-than-air vehicles outperform both fixed wing aircraft and helicopters in certain missions supporting submarines -including ocean surveillance, sonobuoy monitoring, and communications relay functions. Airships are being lifted from the pages of history books to make a vital contribution to tomorrow’s underseas operations.
Steven M. Shaker
CAPT R. S. Anderson, USN(Ret.)