Submarines Have Special Connectivity Needs
By Captain James H. Patton Jr., U.S. Navy (Retired)
Submariners and others who live or die through stealth (or the lack thereof) understand in a visceral sense their needs for and means of connectivity with other entities. Their intuition has been acquired
through long immersion in a common culture. Early in my own submarining career, I was taught that two of the greatest mistakes I could make would be to act on my intuition early in my training but ignore it later, at a senior level.
Connectivity Models
For submarines, unlike most other users, the distinction between passive (listen only) and active connectivity is as important as that between passive and active sonars. Along with its two-way exchange of information, active connectivity involves some degree of compromising the sub's covert posture.
Germany and the United States had radically different submarine connectivity models during World War II. The German model, more consistent with Prussian military philosopher Karl von Clausewitz's concentration-of-forces theory, deployed units that reported status and sightings nightly using covert high-frequency burst transmissions for active connectivity.
The U.S. model deployed submarines with area assignments and general instructions, almost analogous to what Vice Admiral Horatio Lord Nelson would have recognized as operating "in the best interests of the Queen" type of directions, but enhanced with passive connectivity support from headquarters ashore. In theory, this is far less efficient in a military sense, but it resulted in submarines accounting for 60 percent of shipping and 28 percent of warship losses by the Japanese Empire. While accomplishing this, the United States lost 52 submarines; the Germans lost nearly 800 from 1939 through 1945.
Stealth is a submarine's primary defensive weapon system, and vulnerability increases as that stealth is compromised. But some connectivity is inescapable, often resulting in a compromise of vulnerability. Determining the relative desirability of connectivity versus vulnerability involves different variables for submarines than for most users, since stealth is their primary defensive weapon.
Variables of Submarine Connectivity
- Bandwidth: For most users of radio frequency (RF)
Submariners welcome all the bandwidth that can be provided but try not to increase the time-bandwidth product. They prefer preprocessed data (information or knowledge instead of raw data), which allows them to use the increased bandwidth for conducting their business more quickly. The process has been likened to "shipping the wine, not the grapes."
based command-and-control systems, bandwidth is the end-all-and-be-all, and the bigger the communications "pipe," the better. Unfortunately, most immediately fill these larger pipes with various and sundry data, creating the perceived need for yet more bandwidth. - Persistency: In a surface ship, being concerned about the degree of continuous connectivity established is almost unheard of. For a submarine, it's the Holy Grail of efforts to improve communications at speed and depth. RF energy penetrates sea water only to a very small percentage of a wavelength, and data rate (read bandwidth) is proportional to wavelength. This is why passive RF connectivity using extremely low frequency (ELF), with wavelengths of about 3,000 miles, could be received throughout the speed-depth envelope (all possible combinations of the boat's speed and depth) and would be of great use even though receiving a three-character coded alphanumeric message can take several minutes.
With ELF as a persistently available "bellringer" (a low data-rate, passive type of connectivity to alert the sub at speed and depth), the submarine could be ordered to come shallow for higher data-rate traffic if required, or coded messages could be sent (there are more than 46,000 three-character combinations of 26 letters and 10 digits). Unfortunately, because it was devoted almost exclusively to nuclear-powered ballistic-missile submarine (SSBN) connectivity, ELF was torn down as a "strategic systems peace dividend" at the end of the Cold War.
- Quantity: This is almost self-explanatory for a submariner. The maxim is that less is more. A message drafted by a submariner is unlikely to include adverbs or adjectives; often only "yes" or "no." Minimum quantity makes everything easier. A submarine commanding officer is probably the second or third person to read an incoming message, and likely writes outgoing messages himself.
- Latency: Without a bellringer, messages sent to in-transit submarines may not be received for 12 to 24 hours, depending on how often traffic is checked. Frequent message checking significantly slows advance because of the much slower speeds at periscope depth, and the time needed to come slow and shallow. For outgoing messages, the controlling factor is likely the better part of an hour it takes to come safely to communications (periscope) depth and ascertain whether it is safe to transmit.
Determining the longest acceptable latency involves the time constant of the process in question. For example, if it takes 15 minutes to prepare an SSBN's weapon systems to launch, it is entirely acceptable for the message directing that launch to take 10 minutes to receive and authenticate, since the boat begins to prepare when the message first starts coming in.
Operational Considerations
Submariners widely believe that the rest of the joint warfighting establishment expects them to execute network-centric warfare to the same degree as an Aegis cruiser or an Arleigh Burke
class destroyer. But an Arleigh Burke has more than 150 antennas, well above the waterline and usually dry. A Los Angeles or Virginia-class sub has only about 12, 2 of which are bridge-to-bridge walkie-talkies. Less sophisticated submarines are even more restricted in their RF connectivity kits.A World War II operational-analysis concept that has largely grown dusty during the last half-century is limiting lines of approach. Two tangential lines, at an angle defined by a trigonometric function of the target's and the submarine's speed, extend to infinity from a circle with a radius of weapons range drawn around the target's position. For the sub to reach an attack position at that speed, she must be between those lines at the start of the encounter. The concept illustrates why, during the world wars, "fast" (greater than 20 knots) targets were rarely, if ever, successfully attacked in the open ocean with submarine-launched torpedoes.
It also shows how much more dangerous slow, conventional submarines become when armed with antiship cruise missiles (ASCMs) with ranges of 100 miles or more, instead of the World War II
era straight-running torpedoes that were effectively shot from only a mile or two. However, these subs cannot do their own targeting of contacts 100-plus miles away, nor can they go dashing around to search for targets or respond to time-late intelligence from ashore to reach a firing point. Counterintuitively, the submarine platforms that would benefit the most from improved connectivity are those on the low end of sophistication.Optimum connectivity varies with the type of submarine and also the specific mission. For the inflection point to be determined as a function of level of connectivity, versus its contribution to the mission, very careful planning must occur. The figure here shows how this function might vary for two types of submarines executing different missions. As special-operations forces and submariners fully realize, mission-specific planning is essential, as opposed to one-size-fits-all tactics and procedures.
Antisubmarine warfare (ASW) has become increasingly important following an ill-advised post
Cold War lapse in attention; but ASW has become exponentially harder because of quieter platforms, air-independent propulsion, and long-range standoff weapons such as modern ASCMs. It would appear, however, that a vulnerability that might be exploited in an ASW sense could be the connectivity nodes ashore that provide all-source fused targeting information to these otherwise sensor-limited platforms.With these command-and-control nodes degraded, at the very least one would expect that the deployed "mobile minefields" of diesel-electric and air-independent-propulsion subs would have to revert to more active connectivity and greater mobility
which would increase their vulnerability to classic ASW practices and procedures.Whether passive or active, submarine connectivity will continue to improve. However, the submarine will always be a disadvantaged user relative to other warships and most aircraft, because of their operating environment. They have different needs for and means of connectivity. Across sub types, improvements to connectivity will benefit the low end (diesel-electric SS) more than the high end of modern nuclear-powered attack and guided-missile subs.
If we prioritize the variables of connectivity, persistency by far provides the highest and most immediate return on investment, preferably throughout a large portion of the speed-depth envelope. This holds true even if it is only passive and at low bandwidth, since the submarine can then initiate transition to higher-bandwidth options, if only by means of expendable signal ejector-launched fiber-optic-tethered buoys that both U.S. and European companies are now developing.
Those who wonder why submariners should have the capability for superior active connectivity if they will not use it often or to its maximum capacity should be reminded that since the 1960s and 1970s, U.S. nuclear submarines have had perhaps the best active sonar in their Navy. But it has been used only when absolutely necessary.
Regain ASCM Standoff: Improve the Harpoon
By Commander John Patch, U.S. Navy (Retired)
The Navy has not deployed a new or significantly upgraded surface antiship cruise missile (ASCM) since 1985. Hence, the currently fielded Harpoon missile does not adequately address emerging surface threats. We need a smarter, longer-range ASCM now.
In a surface duel with navies from any of the three other major ASCM-producing countries
China, France, and Russia the U.S. Navy would lose. The reason is as simple as it is troubling: the U.S.-made Harpoon ASCM has the shortest range of all comparable missiles, so adversary surface platforms can exploit standoff distance to launch without ever being threatened. An analysis of the Harpoon missile Block improvements points to a solution. It is a cost-effective alternative to the development of an entirely new missile.Aging but Sturdy Weapon
While it is rapidly obsolescing, the Harpoon has proved to be one of the most successful ASCMs ever. Developed at the height of the Cold War by McDonnell Douglass (now Boeing), it met and exceeded expectations of reliability, survivability, accuracy, and lethality. The Harpoon is an all-weather, sea-skimming, medium-range, fire-and-forget, active radar-guided missile with a 500-pound unitary target-penetrating high-explosive blast/fragmentation warhead designed primarily to kill ships. The small but powerful American-made Teledyne Turbojet engine powers the missile out to a 75 nautical mile range, providing surface vessels over-the-horizon capability.
Used to great effect in combat against Libya and Iran, it was the best ASCM available at its initial operational capability date. Many modifications (or block upgrades) since initial production in 1978 offered dramatic improvements, but the currently fielded Harpoon version still retains 25-year-old technology. Block I modifications included:
- IA: lower cruise altitude.
- IB: eliminated terminal pop-up maneuver.
- IC: current version, longer range from JP10 fuel, improved electronic counter-countermeasures, programmable waypoints and terminal maneuver.
- ID: longer missile and larger fuel tank improved range, added re-attack capability. Canceled in 1993 due to "reduced threat environment."
- IG: IC model with re-attack and improved electronic counter-countermeasures, sold to foreign partners.
Block IE is the Standoff Land Attack Missile (SLAM), and IF is the SLAM-ER (expanded response), with further upgrades in the Block IH and IK variants; these are essentially new missiles, air-launch only and not designed for antiship attack.
The Harpoon Block II, designed in 2000, incorporated global positioning system and inertial navigation system guidance alongside Block IG enhancements, allowing accurate use versus littoral (including land) and blue-water targets. While the Navy supported development and allied sales, it procured none for U.S. warships. The Block III upgrade includes major Block II features and adds a two-way data link, providing full missile control and in-flight retargeting.
Despite these improvements, the Navy canceled the Block III program in April 2009. Thus the current Harpoon on Navy surface combatants suffers from serious capability shortcomings in range, countermeasures, target discrimination, and re-attack.
The Handicaps
Range is by far the most serious present Harpoon handicap. Naturally, the United States or an adversary may be able to develop the longest range in the world, but without targeting it is meaningless. Therefore, over-the-horizon targeting (OTHT) is a critical aspect of making the Harpoon an effective weapon system, but discussion of sufficient external targeting information to exploit OTH ASCMs is beyond the scope of this article.
The crux of the problem is that adversary surface ASCM shooters can launch before they are within U.S. Navy surface weapons range. The table here compares current Harpoon range to peer ASCMs.
Of course, first-shot standoff (the ability to shoot first without being in adversary weapons range) requires sufficient target identification and location information, but one cannot assume that the adversary does not have this capability. Some analysts also argue that an air-launched Harpoon with much longer range (120 nautical miles) could eliminate threats before they could fire on U.S. surface combatants. Yet the retirement of the A-6 and S-3 leaves only the P-3/P-8 community as the best equipped and trained to handle focused long-range ASCM attack missions. Because our potential foes increasingly have littoral and surface combatant air-defense capabilities, U.S. P-3/P-8 missions are unlikely to succeed in high-threat areas. A recent RAND study made a similar point:
The air-launched Harpoon is obsolescent in the context of the air defense environment it would encounter over the Strait [of Taiwan] in the event of a war, since its range, like the Hsiung Feng II, is not long enough to allow the carrying platform to be confident of survival.1
Another peripheral concern over the long term, as ASCM ranges increase, is that the United States has a desired ceiling of range performance (300 km) to avoid Missile Technology Control Regime Treaty foreign-sale complications. But China is not a treaty signatory. Defense-industry corporations obviously have a significant interest in making weapon systems easily exportable to allies.
Beyond the range limitations of the current Harpoon, several other key shortcomings merit a weapon-system update. The first is compatibility: the MK 41 vertical-launch system (VLS) found on all U.S. cruisers and destroyers cannot launch the Harpoon. With the removal of the MK 13 missile launcher on the few remaining Oliver Hazard Perry
class frigates, only the MK 141 quad launchers on the Ticonderoga and Flight I/II Arleigh Burke classes can fire the Harpoon. This effectively limits those ships to eight missiles and leaves the FFG-7 and Flight IIA DDG-51s with no ASCM capability. While making Harpoon VLS-compatible would be costly because of booster and vector thrust modifications, the alternative development of an entirely new VLS-compatible missile seems questionable.Additionally, the technological obsolescence of the current Harpoon seriously limits its use in a conflict. U.S. fleet missiles have none of the benefits of extant technical upgrades, such as re-attack, target discrimination, enhanced survivability, and a two-way data link
all of which profoundly expand the tactical flexibility and precision of the Harpoon. Boeing designed Block II and III enhancements partly to overcome known Harpoon limitations for use in a cluttered, littoral environment, in which earlier versions could easily strike civilian vessels or succumb to basic countermeasures.Later blocks even provide an abort option, in-flight retargeting, and limited battle hit assessment data via the data link. The long-range, blue-water war at sea envisioned during the Cold War shaped the Harpoon's early development, but the more complex modern threat environment and contemporary rules of engagement leave commanders handicapped today with Block IC Harpoons.
Addressing the Realities
Clearly aware of Harpoon's shortcomings, Navy leaders in 2009 began an initiative to design a next-generation ASCM. On 30 June, the Defense Advanced Research Projects Agency (DARPA) and the Office of Naval Research issued a $10 million contract to Lockheed Martin to begin design work on a long-range antiship missile (LRASM). A DARPA press release claims the VLS-compatible LRASM will outrange adversary ASCMs and reduce dependence on precision intelligence, surveillance, and reconnaissance sources, data links, and GPS. The missile will also reportedly employ advanced onboard sensing and processing capabilities, allowing precision engagement of moving ships based only on rough, initial target cueing, even in extremely hostile environments.2
However, in light of recent challenges of similar next-generation defense programs, some skepticism is in order. With a summer 2012 estimated flight test, the research and design timeline and the leap-ahead technology promises associated with this missile are quite ambitious indeed. Even if the program survives in an era of spiraling weapon costs, almost certain defense budget cuts, and recurring operational test and evaluation failures, it will likely be much more expensive than Harpoon Block III missiles and take longer than a decade to successfully field.
The obvious question, then, is: Why develop an entirely new missile when advanced Harpoon versions already exist
The Lower-Cost Solution
Navy leaders should examine whether an improved Block III Harpoon is a cost-effective alternative to the LRASM. Many factors argue for the logic in such a course of action. The large number of existing Harpoons in the Fleet and significant block commonality suggests that an upgraded missile could use many recycled Block IC components. Also, Boeing's established Harpoon production lines are still active with Block II and would likely require relatively few changes for a modified Harpoon line.
Similarly, research and development and operational tests and evaluation have already occurred on the Block II and on many design features of the longer-range airframe of the Block ID and the Block III, including possible modifications for VLS compatibility.3 Considering the economies of scale already mentioned, an improved Block III (a theoretical Block IIIA, VLS-capable, with all the technology updates and double the range of the Block IC, because of a larger fuel tank and more energetic fuel) would almost certainly have a lower cost relative to the LRASM.4
Some recommendations follow from the above analysis:
- Cancel LRASM and reroute all funds to Block IIIA production.
- Eliminate the MK 140/141 quad canister launchers, reducing topside weight and radar signature.5
- Ensure in-stride OTHT capability development supports an improved Harpoon when fielded.
The Block IIIA course of action provides a near-term solution with existing, proven technology. The time to arm Navy surface combatants with standoff ASCM capability overmatch is now.
1. David A. Shlapak et al., "A Question of Balance: Political Context and Military Aspects of the China-Taiwan Dispute," RAND, February 2009, p. 117.
2. Philip Ewing, "Research Begins on New Anti-Ship Missile," Navy Times, 14 July 2009, http://www.navytimes.com/news/2009/07/navy_missile_071309w/; and "DARPA Begins Long Range Anti-Ship Missile Program," news release, Defense Advanced Research Projects Agency, 30 June 2009.
3. "Boeing Awarded Contract for Next-Generation Harpoon Block III Missile," news release, Boeing Corporation, 31 January 2008, http://www.boeing.com/news/releases/2008/q1/080131a_nr.html.
4. Directory of U.S. Military Rockets and Missiles. Harpoon by 1991 cost roughly $530,000. According to the Navy, the Block II cost $1.2 million each (see "Harpoon Missile," U.S. Navy Fact File, 20 February 2009, http://www.navy.mil/navydata/fact_display.asp
cid=2200&tid=200&ct=2).5. This would be in keeping with Robert Work's Center for Strategic and Budgetary Assessments report recommendation to create an interchangeable battle network of large combatants. See "Know When to Hold 'Em, Know When to Fold 'Em: Thinking About Navy Plans tor the Future Surface Battle Line," backgrounder, CSBA, 7 March 2007, p. 6.
Alternative Fuels for the Navy
By Colonel Bill Siuru, U.S. Air Force (Retired)
Like the civilian world, the U.S. military is committed to decreasing dependence on crude oil from unfriendly sources. The Navy, which uses nearly 35 million gallons of petroleum-based fuel annually, has a major alternative-fuels program. Besides supporting the service's energy-security strategy, these fuels can reduce greenhouse gas and polluting emissions. The Department of Navy has outlined five ambitious energy objectives for the Navy and Marine Corps:
- By 2012: Demonstrate a Green Strike Group with two "green" power sources: nuclear and biofuel.
- By 2016: Sail the strike group as a Great Green Fleet with nuclear ships, surface combatants equipped with hybrid electric alternative power systems running on biofuel, and aircraft running on biofuel.
- By 2015: Cut in half petroleum use in the service's 50,000 non-tactical vehicle commercial fleet by phasing in hybrid, flex-fuel, and electric vehicles.
- By 2020: Produce at least half of shore-based installations' energy requirements from alternative sources. Also 50 percent of all shore installations will be net zero energy consumers.
- By 2020: Half of the Department of the Navy's total energy consumption for ships, aircraft, tanks, vehicles, and shore installations will come from alternative sources.
About 80 percent of the Navy's fuel, split almost equally, is used for aviation and ships. Thus, the service is looking at alternatives for both F-76 ship-propulsion fuel and JP-5 aircraft fuel. A major goal is drop-in replacements, that is, fuels that are indistinguishable from their petroleum counterparts, so that flight crews will not notice the difference. It will all be JP-5 or F-76 when it gets to the ship.
The Navy is requiring alternative aviation fuels to be the same specifications as JP-5. The shipboard environment adds mandates to both petroleum and alternative fuels. For example JP-8, the military's standard fuel used in everything from aircraft and helicopters to trucks and tanks, is not used shipboard for safety reasons. Instead, JP-5, the same as JP-8 but with a substantially higher flashpoint, is used on board ships.
Navy Biofuels
The Fuels and Lubricants Chemistry Laboratory at Patuxent River, Maryland, has tested about a dozen biofuels derived from sources such as algae oil, jatropha, camelina, soy, animal fats, and agricultural waste. Of particular interest is feedstock not used for food.
Fuels derived from plants are considered carbon-neutral. That is because combusting them does not increase the net amount of carbon dioxide in the atmosphere, since the carbon they contain was originally absorbed from the air as the plants grew.
The Navy requires different biofuels than those now commercially available, such as the biodiesel sold at truckstops or the 50/50 blend of jet fuel and jatropha-based biofuel demonstrated in a Virgin Atlantic Boeing 747. These consist of oxygen-containing compounds called esters, which, although they burn well, absorb water too easily to be suitable for the Navy's maritime environment. Long-term storage is a unique military requirement.
To meet specifications, Navy biofuels will be mixed in a 50-50 blend with conventional petroleum-derived fuel. The challenges of using them include their lesser density and somewhat lower energy content. For example, commercial pure biodiesel, B100, provides about 8 percent less energy compared with petro-diesel. There also can be some material compatibility issues, especially with rubber and elastrometric components like gaskets and seals.
Deadlines Approaching for Business
The Navy plans to have tested and certified the most promising alternative-fuel candidates no later than 2013. As each is approved for use, it will be added to the service's JP-5 and F-76 specifications. The Defense Energy Support Center can then buy the fuel from the lowest-cost provider to meet Navy requirements. Actual usage in the fleet will depend how much industry can produce.
The Defense Energy Support Center recently awarded contracts to Solazyme for an algae-oil-derived renewable F-76 shipboard fuel, and to Sustainable Oils for hydro-treated renewable HRJ-5 for Navy aviation use. More contracts are expected shortly.
The Solazyme F-76 naval distillate is similar to diesel fuel now used on board ships. F-76 has better cold flow properties than a typical ASTM D975 diesel, so it can also can be used in warm waters or polar regions. The renewable F-76 will be produced from algae oil that is deoxygenated and hydrogenated to produce a drop-in renewable fuel replacement. The algae technology reduces greenhouse-gas emissions by over 85 percent compared with standard petroleum-based fuels.
The Naval Air Systems Command successfully flight-tested an F/A-18 Super Hornet using a 50-50 blend of regular jet fuel and camelina-based biofuel on Earth Day, 22 April 2010. A similar effort is also under way to test and certify biofuels for use on ships in diesel engines, gas turbines, and boilers.
To address worldwide logistics problems, Biodiesel Industries and Aerojet have demonstrated the Automated Real-Time, Remote, Integrated Energy System (ARIES). This highly automated, portable biodiesel production unit can be controlled from a remote location, meaning that , a single center can monitor and operate production facilities at numerous locations worldwide.
Following the recent successful demonstration of ARIES, additional capabilities are now being installed. The more complex system will be further demonstrated and validated at the National Environmental Test Site at Naval Base Ventura County, Port Hueneme, California. A key issue is the ability to use inexpensive feedstocks that do not compete with agricultural land use or the production of food.
Finally, the U.S. Air Force wants 50 percent of its fuel to be supplied from domestic sources. For starters, by 2011 the service intends to certify every aircraft in its inventory for operation on alternative fuels, namely a 50-50 blend of JP-8 and Syntroleum's FT fuel. It has already certified or is currently certifying the B-52, C-17, and B-1B on this alternative fuel.
FT designates the Fischer-Tropsch process invented in the 1920s by Franz Fischer and Hans Tropsch to help solve Germany's lack of petroleum. Their solution was to convert coal, abundant in Germany, into synthetic fuels. Germany, as well as Japan, used this ersatz fuel during World War II. By 1944, Germany was producing 124,000 barrels of synthetic fuels daily at 25 FT plants. These methods are again helping to address the ever-increasing global energy problem
compounded today by a growing environmental urgency.