3. Air Vehicles
Rotorcraft are of particular interest to the Army. They are, and will remain, essential for a variety of critical scout, transport, and combat missions. The operational flexibility afforded by vertical takeoff and landing (VTOL) capabilities has created growing civil and military markets, particularly in third world nations. As a result, the helicopter industry has become highly internationalized and interdependent. In addition to the capabilities in the U.S.Canadian industrial base, Germany, France, the United Kingdom, Russia, and Italy are all capable of designing and producing stateoftheart military rotorcraft. Japan, Malaysia, India, and South Africa all have substantial capabilities for rotorcraft production. India and South Africa have indigenous military helicopter development programs. Other countries, notably Malaysia and China, have acquired modest capabilities (principally through licensing arrangements with other countries) in rotorcraft manufacturing to meet local market needs. These countries are not currently at a level that would contribute to significant advances in technology, but could develop niche capabilities in the future.
Competition for international military sales is intense and marketing rights and export prospects have affected a number of development decisions, particularly in international programs. Such market forces continue to push worldwide developments. Foreign capabilities may offer opportunities to reduce the cost of improving each of the key technology subareas: aeromechanics, flight control, structures (including survivability and as a major consideration signature reduction), and subsystems. Table E6 and the following paragraphs summarize potential prospects.
Table E6. International Research CapabilitiesAir Vehicles
|Aeromechanics||Rotorcraft design||Rotorcraft; CFD||Rotorcraft||CFD; hypervelocity||Russia
Wind tunnel test facilities
|Flight Control||Active harmonic control||Adaptive controls; flybylight||Control theory||Sweden
| Crash survivability; CC matrix ceramic
|Smart structures; fatigue||Ceramics; composite materials & structures||Malaysia, China
Rotorcraft structures; Ti & steel alloy structures
|Subsystems||FADEC; rotor systems||Advanced cockpit systems||Avionics cockpit system||Israel
Advanced cockpit systems
|Note: See Annex E, Section A.6 for explanation of key numerals.|
Aeromechanics technology includes multidisciplinary efforts in acoustics, aerodynamics, rotor loads, vibration, maneuverability, and aeroelastic stability. The goal is to improve the performance of rotorcraft while reducing noise, vibration, and stress loads inherent in helicopter operation. Major efforts involve refining analytical prediction methods and testing capabilities, and improving the versatility and efficiency of modeling advanced concepts. Another area of interest is attaining a smoother and quieter ride, which will improve performance and also enhance public acceptance. Technical challenges include the inability to accurately predict and control a number of factors:
Stall and compressibility characteristics of airfoils
The proliferation of lowcost, highperformance computing (HPC) systems has lead to a growing worldwide interest in computational fluid dynamics (CFD) to address many of these issues.
Use of CFD for design of rotors and blades can enhance helicopter speed, maneuverability, and lift capabilities, while reducing acoustic signatures and structural vibration. While the United States is the world leader in CFD and related techniques, France, Germany, and Israel have complementary worldleading efforts to improve and develop analytical techniques and generate experimental databases that may contribute to ASTMP goals in this area. The U.K. has strong capabilities in rotor and overall rotorcraft design, and Italy and Sweden have noteworthy capabilities in aeromechanical design. In addition, Japan has special skills in CFD especially related to hypervelocity vehicles, and finally, Russia has special strengths in wind tunnel test facilities. Russia has also fielded some of the most capable military rotorcraft in terms of aerodynamic performance (speed and lift capability).
b. Flight Control
Flight control technology defines the aircrafts flying qualities and the pilot interface. Helicopters are inherently unstable, nonlinear, and highly crosscoupled. Advances in smaller, more powerful computers hold tremendous promise in this field, to allow realization of the full potential of the rotorcrafts performance envelope and maintenance of performance even in poor weather and at night. Integrating flight control with weapons control is of great interest, to permit improved pointing accuracy and the use of lowercost unguided rockets as precision munitions. Other goals include improved external load handling at night, and increased exploitable agility and maneuverability. Technical challenges in flight control include:
Knowledge of rotorcraft response and interactions with load suspension dynamics
Foreign countries leading in flight control technology include the United Kingdom, France, and Germany. The U.K. has special capabilities in harmonic control for noise reduction. France has strong capabilities in adaptive controls and in flybylight technology. Germany has strengths in several areas that are of interest. One of the most important relates to groundbased and inflight simulation studies on handling qualities. Specific areas of concern are the investigation of crosscoupling requirements, gust rejection for rate response systems, and the response time delay limits for high bandwidth response systems. Continuing work using Germanys inflight simulator and correlated U.S. groundbased simulators has produced a viable database to build on, which could not be accomplished using U.S. assets alone. In the area of stability and control analysis, the U.S. predominantly uses a frequency domain method, whereas the Germans predominantly use a timedomain approach. Each technique has inherent advantages and disadvantages. A coordinated approach combining the strengths of both techniques yields the most promising path to success in detailing complete and accurate portrayal of flight control system design and performance parameters. This technology provides a critical link bridging theoretical design, prediction, simulation, and test analysis. In addition, Sweden has some ongoing efforts in adaptive controls that are of interest.
Science and technology related to structures aims at improving aircraft structural performance while reducing both acquisition and operating costs. Virtual prototyping to optimize structural design for efficiency and performance is of particular interest to remove a large portion of the risk involved in exploring new concepts and moving rapidly from concept to production. An integrated product and process development approach will be used. The reduction in dynamically loaded structural stress prediction inaccuracy is another area of great interest, as is reducing the production labor hours per pound for composite structures. Breakthroughs in these and other areas will lead to improvements in maintenance and production costs, as well as reducing the empty weight fraction of the airframe, while increasing durability, performance, and ride comfort. Technical challenges in structures include:
Accurate methodologies for flight regime recognition algorithms
Advanced composite structures and flybywire/light are becoming common in international aircraft. Technologies for military systems reside primarily in the few countries that produce military helicopters. Predominant among these are France, Germany, the United Kingdom, and Italy. The United Kingdom has strong capabilities in composites and in smart structures. Crash survivability is an area of special interest. France has expertise and in general is on a par with the United States in this area. Survivability depends on a number of factors including equipment performance, which may be enhanced by more efficient design and testing of aircraft structures. Of particular interest is the testing of advanced structural concepts and manufacturing processes for composite and thermoplastic materials for primary helicopter airframe structures. In addition to the above countries, Canada has strong capabilities in fracture/fatigue analysis, and Russia in titanium and steel alloy structures. Finally, Japan has worldclass expertise in ceramics and composite materials.
Rotarywing vehicle subsystems encompass a broad range of S&T topics related to support, sustainment, and survivability of aircraft systems and their associated weaponry. Five key technology areas are of interest:
Reduction of radar cross section (RCS)
Technical challenges relate to modeling and analytical predictions for components and materials used in signature reduction and hardening against threat, and developing rugged, costeffective, nonintrusive monitoring techniques, sensors, algorithms, and methods.
Several countries have capabilities of interest in subsystems for rotorcraft. Germany, Japan, and Israel all have strong capabilities in advanced cockpit systems, but the German work on cockpit integration is of special interest. Germany is a recognized world leader in cognitive decisionaiding, knowledgebased systems and in highspeed data fusion. It is actively pursuing integration of these capabilities in vehicle driving systems that could be of significant value. The United Kingdom is doing significant work on full authority digital engine control (FADEC). In addition, Japan has strong capabilities in avionics, based upon its worldclass electronics capability.
AMC POC: Dr. Rodney Smith
Army Materiel Command
5001 Eisenhower Blvd.
Alexandria, VA 223330001
IPOC: Mr. Dennis Earley
U.S. Army AMCOM
St. Louis, MO 631201798
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