The helicopter has unquestionably had great effect upon modern warfare, despite its troubled history of inadequate funding, inter- and intraservice rivalry, quests by advocates for too extravagant performance improvements, and many other obstacles. It has developed from a frail and unreliable machine, best suited to the recovery of nearby wounded personnel, to become a formidable hunter-killer. Its lift capacity has increased from pounds to tons, and through the years it has remained the most welcome sight in the world to survivors in distress.
Even more important than its engineering and design development, its backers have learned how to use the helicopter efficiently, getting the most from its capabilities and adapting to an ever-varying series of wartime scenarios. The helicopter reached the peak of its effect upon warfare in Vietnam, where in the hands of dashing, daring combatants, it shaped and controlled the battlefield. In later wars, its role, while not so dominant as in Vietnam, has been ever more essential to the conduct of conflicts, particularly in the difficult situations encountered in the Middle East. There, the suppression of enemy assaults, the resupply of outposts, and the delivery of special-operation forays make the helicopter invaluable.
In the long run, and quite inadvertently, the helicopter has arrived at an invaluable, if not optimum, point for most civil and military requirements. The term “inadvertently” is used because the helicopter’s current performance standards in terms of speed, range, reliability, and maintainability have not reached the goals so earnestly sought in years past when advanced new designs were coming off the drawing board. Instead, in the United States we have seen the basic helicopter designs of the 1970s and 1980s benefit from a steady, moderate improvement in capability. In practical terms, the American helicopter of contemporary production is a combination of decades-old basic design and thoughtful improvements in equipment, reliability, and maintainability. The people operating them accept the existing standards of performance, understand the limitations, and use this as the basis for their planning.
In practical terms, there has been a symbiotic relationship between the industry and the user that has withstood, and offset, the problems caused by the tribal instincts and managerial mistakes noted in the first paragraph of this chapter. This has resulted in a seasoned, mature series of American helicopter designs that continue to serve their military users well on many traditional missions.
Despite declines in the total U.S. helicopter fleet since the Vietnam War, the demands placed upon it have been great. Rising costs have forced the services to examine methods by which the number of types of helicopters can be reduced, thus simplifying maintenance and logistic efforts. As an example, the U.S. Navy is developing a master plan that places helicopters at the forefront of standard operations. Part of the plan is to reduce the number of helicopter types in the force structure to just three, all CH-60 variants of the Sikorsky Black Hawk, to handle anti-submarine warfare, anti-surface threats, mine warfare, CSAR, special operations, and vertical replenishment missions. It is worthwhile here to examine briefly the history of the Black Hawk as an example of how an aging but capable type can be adapted for multiple uses over many years, especially when the obvious new replacement vehicle is controversial.
Two Sikorsky model lines, the S-65 and S-70, illustrate this situation very well and demonstrate how careful and deliberate improvements over time can offset the failure to achieve technological breakthroughs to totally new performance levels. Other helicopters, including the Boeing CH-47 Chinook and, as we have seen, the many Bell variants of the Huey, have maintained their value through the same process.
The S-65 became one of the Western world’s largest and most versatile helicopters since its first flight as the twin-engine CH-53 Sea Stallion on October 14, 1965. Playing upon its own strengths, Sikorsky created a hybrid design using the fuselage, engine, and rotor system of the proven and popular CH-54 Tarhe heavy lifter. The result was a large, fast assault transport capable of carrying thirty-seven fully equipped troops; it also created a platform from which many variants could be derived over the years. On March 1, 1974, a three-engine version, the CH-53E Super Stallion, appeared. (The CH-53E became the new heavy-assault helicopter, with its predecessor CH-53 models being reclassified as medium helicopters.) Among the more than twenty variants, the USAF used the S-65 as the basis for rescue and Pave Low helicopter programs.
Sikorsky next drew on its experience to create the S-70, smaller than the S-65 and intended to replace the Bell UH-1 series. The first example, the YUH-60A, was first flown on October 17, 1974, as the winner of the competition for the U.S. Army’s Utility Tactical Transport Aircraft System (UTTAS). The UTTAS was to represent the “lessons learned” from the intensive wartime use of the Bell UH-1 Huey helicopters, which performed so many different duties in Vietnam. After much thought, a design specification was issued by the Army. The Sikorsky response was deemed better than the corresponding Boeing Vertol offer, and the Sikorsky YUH-60A prototype made its first flight on November 29, 1974. By mid-1979, the Black Hawk was beginning to replace the Hueys within the 101st Airborne Division.
The Black Hawks have a muscular, almost sinister appearance, with a large fuselage capable of carrying the two-man crew and eleven personnel. Two General Electric turbo-shaft engines sit atop the fuselage, driving a four-blade main rotor and generating sufficient power to allow the Black Hawk to cruise at 175 mph. The commodious fuselage can handle about three thousand pounds of freight internally, while up to an eight-thousand-pound load can be carried externally. It can be fitted with 30-mm chain guns, machineguns, mini-guns, and Hellfire missiles. Extra fuel tanks, formed as part of the optional wing stubs, can be added. These variations have enabled it to survive and serve in combat operations since its debut in the 1983 invasion of Grenada.
Yet the Black Hawk, in all its almost fifty variations including export models, remains essentially a helicopter with a 1970s pedigree. It has been improved considerably over the years, and it teaches that in the world of rotary-wing aircraft, the expense of major performance improvements becomes insupportable after certain thresholds of range, speed, and hover altitude are attained. As desirable as further improvements in these and other areas may be, they come at a price too high to pay compared to an improved Black Hawk.
The next step in this linear process has seen the Black Hawk’s multiservice stable mate, the CH-53, so severely stressed by the demands of the Middle Eastern wars that the supply of aircraft to be remanufactured is being exhausted. The best way to maintain the capability was to call for a “new” CH-53, the much larger, more modern, and more powerful CH-53K, now in the process of manufacture at Sikorsky. The Heavy Lift Replacement (HLR) program calls for the purchase of 156 new-built helicopters derived from the CH-53E, with an initial operating capability set for 2014-15.
With a program value of more than $4 billion, the CH-53K is perhaps the current pinnacle in the process of refining past designs for the future. Sikorsky promises a large increase in range and payload coupled with a 42-percent reduction in direct maintenance costs, a 68-percent reduction in maintenance hours per flight hour relationships, and much increased survivability. There is a 20-percent reduction in fuel consumption, despite having three General Electric GE28-1B turbo-shaft engines of 7,500 shp in place of the 4,380-shp engines of the CH-53E.
The CH-53K fuselage is obviously larger and bulkier than its predecessor. Composite construction is used for the fuselage and the rotors, and it features an elastomeric rotor head, with hydraulic blade folding. With the CH-53K, the Marine Corps has reached a point in helicopter development that carries it at least into the second half of the twenty-first century.
Yet even as the Marine Corps continues to rely on rotary-wing aircraft for many traditional tasks, it has, in a way unique among the services, pressed for advances beyond the helicopter with the MV-22 Osprey. And as we will see, the same essential question of expense versus performance improvement is a current problem facing the MV-22.
In Europe and Russia, attack helicopters are still advocated, with the formidable Westland Lynx, Eurocopter Tiger, and Mil Mi-28NE offering new capabilities. These, like the U.S. Army Apache helicopter, face a most demanding question in how well will such attack-type helicopters do in future military conflicts, where the intensity of combat is certain to increase substantially. Admittedly, the problem is more germane to the American situation, engaged as it is in the global struggle against terror, but ultimately the new criteria of combat will apply to all countries.
The real difficulty facing helicopters is that the hostile environment in which they must operate has become more and more lethal. In the years to come, the threat will grow from ragged attacks by rocket-propelled grenades to very much improved MANPAD SAMs. These will continue their rapid proliferation in all areas of the world. Helicopters are still very vulnerable to small-arms fire, and the traditional Kalashnikov-style weaponry will likely be augmented in the future by more powerful automatic weapons firing even more lethal projectiles.
Since Operation DESERT STORM, most American military operations have faced relatively primitive military opposition. This may still be the case in large part, but there are almost certain to be requirements in the future to fight more sophisticated enemies armed with more advanced weapons such as radar-aimed anti-aircraft guns.
Possibilities for Improvements
Before coming to a conclusion on the future role of helicopters, it might be well to examine the possibilities for improvements in the type, which will enable it to sustain itself in the conflicts to come.
No new military helicopter has been procured for the U.S. armed services since 1990. The Apache was the last “new” rotary-wing aircraft to come into service, and it has been followed only by the Bell Boeing V-22 tiltrotor. It seems pertinent then to ask, after all the R&D, production, and experience since the helicopter came into being as the Sikorsky VS-300 in the 1930s, what the wildest hopes might be about the helicopter of the future.
The ideal, if somewhat magical, new helicopter would have incredible new rotors that would be virtually noiseless, stealthy, and able to absorb tremendous battle damage. The rotors would be operated by a low-drag hub with a totally new mechanism, simple and effective, for transferring the power from the engines to the blades. The body would be a lightweight composite structure able to shrug off small-arms fire and even absorb a hit from a rocket-propelled grenade. Smaller but more powerful engines would propel it at high speeds (more than three hundred knots) over long ranges (1,000 miles) to the LZs.
Sadly, no such magic helicopter is foreseen in any predictions, simply because the basic characteristics of the helicopter impose drag and performance penalties that currently cannot be overcome. By far the most important of these is the fundamental feature of the helicopter itself—the rotor. The inherent aerodynamic conflict of the rotor’s advancing blade and retreating blade has been modified to some degree by clever rotor design and the addition of trim control surfaces. However, as the rotor speed, size, and design changes, the problems grow more complex, and to most authorities it seems reasonable to assume that the maximum speed available to a helicopter is limited to about 250 knots (287.1 mph). As speed increases, the rotor transitions from being a pure lifting device to acting somewhat as a drag chute. If the rotor is to be retained, not stowed or somehow retracted, the 250 knots is generally conceded to be the achievable limit.
This putative maximum helicopter speed has already been attained. The current speed record for helicopters is held by the versatile and well-liked Westland Lynx. On August 11, 1986, a specially modified version, piloted by Trevor Egginton, set an absolute speed record for helicopters over 15- and 25-kilometer courses at 249.09 mph. This Lynx had specially tuned engines and used the British Experimental Rotor Programme (BERP), which features sweepback of the rotor from a notch at the outer end of rotor blade.
There is always the future hope that if the designer can “unload” the rotor, so that it is not imposing any drag, and another means of propulsion is added, then the maximum speed might advance to more than 250 knots. Beyond this point, one has to design a retractable rotor, one that folds up and stows to minimize drag. The entire propulsion system would then provide power for thrust rather than turning the rotor, and you essentially would have a compound helicopter that uses its rotor only for vertical ascents and descents.
As noted previously, compound helicopters have been tried over the years, and none has reached production. The Department of Defense defines a compound helicopter as “a helicopter with an auxiliary propulsion system which provides thrust in excess of that which the rotor(s) alone could produce, thereby permitting increased forward speeds; wings may or may not be provided to reduce the lift required from the rotor system.” There are currently proposals for compound helicopters in the marketplace. The Piasecki X-49 is a twin-engine experimental compound helicopter based on the Sikorsky YSH-60F Seahawk but has lifting wings and uses the proprietary Piasecki vectored thrust ducted propeller design (VTDP) for propulsion. The changes include a third engine, a forty-five-inch extension of the fuselage, wings with a forward sweep, a general drag reduction, and a fly-by-wire control system.
Company president John Piasecki believes that applying the Speedhawk conversion to the UH-60 fleet would essentially provide a new generation of capable helicopters at a minimum of R&D and production expense. The same system could be applied to other helicopters as well.
Sikorsky has experimented with its X2 technology demonstrator, an advanced compound helicopter that uses coaxial rotor blades and auxiliary propulsion. First flown on August 27, 2008, the X2 drew heavily on the experience Sikorsky gained in the Comanche program. The X2 has an integrated fly-by-wire system to coordinate its engine/rotor/propulsion systems. The rigid rotor blades are designed with a high lift-to-drag ratio, and drag has been minimized. Sikorsky achieved its goal with an unofficial speed record of 250 knots in 2010. With the two rotors turning in opposite directions to cancel torque, no rear-mounted anti-torque rotor is necessary. Instead, the power is channeled to a pusher propeller.
As no compound helicopter has been placed in production, it has become necessary to “remanufacture” existing proven helicopter types so that they can continue in service. In the remanufacture process, important incremental improvements are introduced. The UH-60 featured a titanium spar of immense strength and a strong, crash-resistant construction. The Apache has rotor blades designed to be resistant to gunfire. Payloads have been increased considerably on most. The new Sikorsky CH-53K can lift 40,000 pounds, about twice what the dedicated heavy-lift Sikorsky CH-54 Tarhe could do. There have been reductions in noise levels, helicopters are more maneuverable than before, and their reliability is much better. New night vision, navigation, and maintenance equipment has been introduced, and new flying techniques have evolved.
There is already considerable experimentation with the UAV helicopter, a rotary-wing development in the vein of the successful Predator and Reaper UAVs that have gained increasing prominence. Without the requirement for a crew and all the concomitant load of safety and comfort features, the UAV helicopter offers possibilities for moderate improvements in range and speed. However, it is ultimately limited by the same features as a full-sized manned helicopter—the inevitable rise in drag of the rotor as speed is increased. It is an alternate approach to using helicopters but not an adequate substitute for many of their missions.
So it remains that standard systems become by default the basic helicopter of choice: Black Hawk, Chinook, CH-53K. All of these are adaptable, have been built in many variations, and face increasingly competent weaponry. Improvements to these workhorse helicopters are often added externally, creating more drag rather than boosting speed and range.
One drastic solution always seems to spring so readily to the lips of military leadership when armament deficiencies are found: to “take it out of the hide of the troops.” This has certainly been the case with the helicopter in the past, as the leadership accepted high casualties in exchange for its continued use on the battlefield. In combat, certain techniques were established to make the helicopter more survivable. It was found in Vietnam that some 80 percent of damage inflicted on helicopters occurred during an approach to the LZ. Pilots soon crafted special techniques for the approach, landing, and takeoff phases of their missions. In many respects, they are only Band-Aids, but they aid in survival. Experience has dictated new procedures, including the following:
1. Continuously vary takeoff and landing directions.
2. Continuously vary routes, altitudes, directions, etc.
3. Do not follow predictable landmarks, such as riverbeds, streets, etc.
4. Never fly over populated areas if they can be avoided.
5. Always seek to have fixed-wing protection and make sure that rescue forces are available.
6. Always be aware of the possibility of collision. Maintain 1,500 feet of distance.
7. Have a portfolio of tactics for insertion and extraction so that you can use different techniques on an unpredictable basis.
8. Always be aware that unprepared LZs in combat areas are filled with hostile possibilities, including rocket-propelled grenades, landmines, and other defenses. In addition, the helicopter rarely has surprise on its side, given its noise.
9. Always be aware of the reflective qualities of rotor blades at night. The slightest light will illuminate them and give the enemy a target.
10. To repeat, never be without overwhelming firepower and without rescue capability.1
Sadly, given the effort and expenditures made over the decades, only one brand-new type of vertical-lift aircraft has so far been introduced to the Middle East conflict, the Bell Boeing V-22 tiltrotor. The Osprey is unquestionably a tribute to the persistence of the United States Marines and the uncanny ability of that service to somehow insist on acquiring new equipment despite its small size, small budget, and modest place on the procurement chain. It had succeeded previously with a V/STOL (vertical/short takeoff and landing) jet lift fighter, the McDonnell Douglas AV-8B Harrier, and is now “all-in” on the development of the Lockheed Martin F-35 tri-service aircraft. In rotary-lift aircraft, it has backed successfully and against great odds the Bell Boeing V-22 Osprey.
Excerpted from How the Helicopter Changed Modern Warfare; Walter J. Boyne; Gretna, Louisiana; Pelican Publishing Company, 2011; 352 pages; $29.95