HEAD

S-70A (UH-60M Black Hawk, HH-60M)

 
 

Background


At the time when this history of the UH-60M was prepared in December 2011, less than one quarter of the projected production quantities of this new Black Hawk model had been produced. In July of that year, 300 units had been delivered out of a planned 1200 units expected to be procured by the U.S. Army in addition to several hundred units expected to be delivered to foreign military organizations. As a result of normal product improvement efforts, certain of this model’s physical and performance attributes as well as its mission systems will change with time. Accordingly, the UH-60M characteristics as described herein will likely be updated periodically to reflect significant configuration and/or performance changes. Readers are encouraged to contact the Archives if more current information is needed.


Conceived during the 1990s, the UH-60M was planned to be a major upgrading of the U.S. Army’s UH-60L Black Hawk model through the incorporation of new aerodynamic, structural and electronic technologies. Its rotor system was the first of the Black Hawk/Seahawk series to take advantage of major advancements in rotor blade aerodynamic and composite material technologies that were not available when the Black Hawk was first designed nearly 30 years earlier. In addition to these new technologies, the chord of the main rotor blade was increased by 16% to achieve higher cruise speeds, especially at altitude. The UH-60M also incorporated major advancements in vibration control technologies developed by Sikorsky for its S-92 commercial program. In addition, its cockpit was brought up to the latest military standards of the time with regards to display technology, digital avionics, flight control components and modular open architecture systems.

S-60A (UH-60M)-1

n March of 2001, the U.S. Defense Acquisition Board approved the Army’s plan to upgrade the Black Hawk configuration to achieve capabilities considerably improved over those of the UH-60L developed 12 years earlier. The Army’s planned upgrades included improved flight performance, full compatibility with the emerging digital battlefield, enhancement of survivability as well as other improvements to increase operational effectiveness while reducing operation and support costs.  Shortly after its plan was approved, the Army awarded Sikorsky a $200M contract to develop and evaluate the UH-60M. The Mike model first flew in 2003 and it began to be manufactured in mid-decade with first delivery achieved on July 31, 2006.

The basic missions of the Mike model were the same as the previous “L” and “A” models, which included transport of the U.S. Army 11-man rifle squad, medical evacuation, resupply and battle zone command and control. One of the factors behind the need for a new troop assault Black Hawk model was the increasing cost of operation resulting from the aging of the UH-60A and L models as they approached their design service lives, accelerated by the increased operational tempo during the conflicts in the Middle East.  Another factor was the need to restore performance that was lost because of weight growth, which was similar to the reason that the UH-60L was developed earlier to replace the UH-60A model. However the cause of this weight growth was very different. The weight issue for the “L” came about as a result of growth in the useful load carried during the primary troop assault mission rather than growth in empty weight, which was the case for the “A” model. That growth was caused by an increase in the number and in the unit weights of the crew and troops as equipped for the Air and Land Warrior roles and capabilities.

Two operational changes occurred during the 1990 decade that required this increase in useful load. The first was recognition that an additional crewmember was needed to serve as a dedicated second gunner during operations in the battlefield. This fourth crewmember would be able to provide suppressive ground fire in the zone not covered by a single gunner who had visibility only to one side. The second change was that the weights of both the crew and the 11-man squad had to be increased to reflect the equipment escalations of the new Air and Land Warrior concepts. Unit weight of the future Land Warrior had increased to 290 pounds from the 240-pound value allocated for each soldier when the Black Hawk was designed in 1972. This weight increase took into account body armor along with improvements in communications, enhanced vision capability, GPS positioning, and other new features of the soldier’s equipment package. In addition, the upward trend of body weight over time had to be considered.

All together, the weight of the added gunner plus the heavier unit weights of crew and troops added approximately 900 pounds to the lift requirement for an 11-man squad regardless of which UH-60 model carried this newly defined squad and crew. With that increase in useful load added to the improvements made to cockpit displays and integration, flight control systems, survivability equipment, airframe strengthening and other needed changes, the challenge for the design of the “M” model was not only to restore flight performance but also to provide margins for future growth.

That performance challenge was met by use of new technology main rotor blades that had a 4% higher efficiency as well as greater speed and maneuver capability plus installation of T700-GE-701D engines that produced 4% more power as well as improved durability. Together, the new rotor blades and the new engines increased lift by approximately 1000 pounds to more than compensate for the weight growth. The improvements in useful load and changes in weight empty and gross weight for each of the three Army troop assault versions are compared below.

 

UH-60A

UH-60L

UH-60M

Useful Load

5710 lbs.

5924 lbs.

6882 lbs.

Empty weight

11,284 lbs.

11,782 lbs.

12,500 lbs.

Mission weight

16,994 lbs.

17,706 lbs.

19,382 lbs.

Max gross weight

20,250 lbs.

22,000 lbs.

22,000 lbs.

 

Cruise speed and climb performance are compared in the table below with speed based on 100% maximum continuous power and vertical climb based on 95% intermediate rated power in accordance with Army performance ground rules. Ambient conditions are 4000 feet altitude and 95 degrees F. The slight drop in cruise speed of the “M” compared to the “L” is caused by acknowledgement of the drag of added antennae and external systems present on the “L” but not factored into flight manual performance at the time.

 

UH-60A

UH-60L

UH-60M

Cruise speed at GW of 16,800lbs.

140 knots

155 knots

153 knots

VROC at GW of 16,800 lbs.

377 ft./min

1315 ft./min

1646 ft./min

VROC at GW of 18,000 lbs.

Zero ft./min

592 ft./min

994 ft./min

 

Configuration Features


The external configuration of the UH-60M is essentially unchanged from its predecessor “L” and “A” models however significant design changes were made in main rotor blades, propulsion system, cockpit and avionics system, cabin structure and in crew and troop seat crashworthiness features

The most significant improvements incorporated in the UH-60M are noted in this figure. The HIRSS 2K refers to an early version
of the Hover Infrared Suppression System on the UH-60M.  It was later renamed the Improved Hover Infrared Suppression System

Increased Performance Main Rotor

The original YUH-60A design of 1972 was able to achieve a record high rotor aerodynamic efficiency that resulted in excellent aircraft climb as well as cruise performance. It achieved that efficiency by using cambered airfoil shapes, high non-linear blade twist plus an unusual swept tip design that improved performance in both hover and high-speed flight modes. During the next quarter century, Sikorsky demonstrated further advances in rotor efficiency through refinement of all of these critical blade parameters, particularly airfoil shape and blade tip geometry.

The transition was also made from an all-titanium blade spar to an all-composite spar to reduce manufacturing cost while retaining the torsional stiffness, fatigue strength and survivability characteristics of the Black Hawk’s original titanium blade spar.

The figure below compares the key features of the new wide chord blade for the UH-60M with the original standard rotor blades of the UH-60A/L models.

The chord of the composite blade for the M model was 1.75 in. (16%) wider than the
A and L blades increasing both cruise speed and maneuverability. Its new airfoil contour
and blade tip airfoil and dihedral shape further improved hover and vertical climb performance.

Advanced Vibration Control Technology

During the 1990 decade, Sikorsky pioneered a major improvement in aircraft vibration control engineering through the application of active self-adaptive technology to achieve lower vibration levels. With this technology, acceptable vibration levels could be achieved with far less vibration suppression weight than earlier Black Hawk models had to carry. This new system utilized an Active Vibration Control System (AVCS) to reduce 4/revolution vibration throughout the airframe. The AVCS eliminated the need for the passive spring-mass units carried in all prior Black Hawk models thereby significantly reducing weight. The AVCS also maintained consistent vibration performance when rotor speed deviated from its nominal value and avoided the loss of effectiveness characteristic of passive absorbers when operating at off-design frequencies.

The AVCS was able to reduce vibration at lower weight because it was a distributed system able to attenuate vibration in selected zones within the airframe. Force generators of the AVCS could be located wherever necessary throughout the fuselage to generate forces so as to cancel out local vibrations. The heart of the system was a closed-loop algorithm that calculated the force generator commands required to minimize vibrations as measured by accelerometers located throughout the cockpit and cabin. A feedback control algorithm processed a tachometer signal, providing frequency and phase information, and also processed accelerometer signals that feed back local vibration conditions. The AVCS computer calculated the required force generator commands and sent them digitally to an electronic unit. This unit then converted the digital signals to analog signals, which then were sent to electric motors within the force generators. These motors drove counter-rotating eccentric masses to generate forces of appropriate magnitude and frequency to cancel fuselage vibrations.

In the UH-60M, a force generator capable of producing 1000 lb. was located in the forward cabin overhead, replacing a heavy spring-mass absorber. In addition, generators able to produce 450 lb. of force were located one in the left landing gear stub wing and one in the cockpit nose.

Digital Avionics and Integrated Displays

All key aspects of the UH-60M cockpit were brought up to latest military aviation standards regarding display technology, digital avionics, digital flight control components and modular open architecture systems. Its new cockpit incorporated dual digital data busses and advances in digital avionics architecture together with a much improved flight control system. Four-color multi-function displays (MFDs) were used in the new cockpit designed to increase pilot situational awareness and interoperability with joint forces on and in the battlefield area. Among the main objectives of this cockpit upgrade was to significantly improve the UH-60M’s ability to communicate and operate on what is referred to as the 21st century digital battlefield. Digitized features and equipment assured more precise long-range navigation, command and control interoperability and were compatible with future air traffic management requirements. The new cockpit incorporated an improved message and data transfer capability as well as dual embedded global positioning and inertial navigation systems.

Significant improvements in pilot workload and operational capability were achieved by major upgrade of the aircraft’s flight control system. Dual digital computer flight control computers were installed, along with a fully coupled flight director system, providing stability augmentation, trim and flight path stabilization functions. A major benefit of the new control system and the integrated displays was the ability to conduct combat operations during degraded visual conditions with more precision and safety.

The redesigned and smaller instrument panel containing the four MFDs all of which were 6 X 8 inch active matrix liquid crystal displays are shown in the illustration below. The traditional communication and navigation avionics installed in earlier UH-60A/L models including many flight instruments were replaced by the MFDs. They provided primary flight, navigation and tactical information and they were fully integrated with a digital moving map displaying real-time aircraft position and terrain information, a Stormscope for detecting lightning activity, and a radar warning system.

S-70A (UH60M)-4

Four multi-function displays with a shortened instrument panel provided greater visibility of terrain and ground
personnel. Two control display units were installed in the center console. A Forward Looking Infra-Red (FLIR)
could also be installed to permit safer operations during decreased visibility and night conditions

S-70A (UH-60M)

The cockpit arrangement and displays shown are typical of earlier UH-60 A and L versions that were based on
conventional analog instruments as well as non-integrated avionic units.

General Arrangement Drawing

 

S-70A (UH-60M) 6E

Mission Systems

The major cockpit upgrade of the Mike model provided the capability to achieve standardization of equipment and training across Black Hawk derivative models as well as with other Army helicopters. Its new cockpit incorporated dual digital data busses and advances in digital avionics architecture together with a much improved flight control system. Four color multi-function displays (MFDs) were installed to increase pilot situational awareness and interoperability with joint forces on and in the battlefield area. Among the main objectives of this cockpit upgrade was to significantly improve the UH-60M’s ability to communicate and operate on what was referred to as the 21st century digital battlefield. Digitized features and equipment assure more precise long-range navigation, command and control interoperability and are compatible with future air traffic management requirements. The new cockpit incorporated an improved message and data transfer capability as well as dual embedded global positioning and inertial navigation systems.

Significant improvements in pilot workload and operational capability were achieved by major upgrade of the aircraft’s flight control system. Dual digital computer flight control computers were installed, along with a fully coupled flight director system, providing stability augmentation, trim and flight path stabilization functions. A major benefit of the new control system and the integrated displays was the ability to conduct combat operations during degraded visual conditions with more precision and safety.

TheUH-60M was also equipped with new crashworthy crew and troop seats containing adjustable energy absorption features. These features provided protection for a wider weight range to accommodate both male and female occupants. Provisions for air bags to be deployed during rapid decelerations were included in the redesigned cockpit.

General Characteristics and Performance

The performance and specifications presented below accurately describe the UH-60M model at a point in time. Some variation to these data can be expected as a result of subsequent engine power rating changes and aircraft design changes.

  • Main rotor diameter: 53.6 ft., 4 blades, airfoil SC2110 and SSCA09 in the tip region.
  • Aft swept anhedral tip.
  • Main rotor blade chord: 24.25 inches.
  • Main rotor solidity: .0913, main rotor tip speed: 725 fps.
  • Main rotor head flapping hinge offset of 15 in.
  • Tail rotor diameter: 11 ft., 4 blades; chord .81 ft., airfoil SC1095.
  • Tail rotor solidity: .1875.
  • Tail rotor tip speed: 699 fps.
  • Main gearbox rated power: 3,400 HP.
  • Main gearbox input/output speeds: 20,900/258 rpm.
  • Installed power: Two T700-GE-701D engines, intermediate rated power: 1,857 HP at SL-STD conditions.
  • Weight empty: 12,500 lb.
  • Mission gross weight: 19,382 lb.
  • External cargo hook capacity: 9,000 lb.
  • Performance: vertical rate of climb TBD fpm and cruise speed of TBD knots at 4,000 ft. 95 degrees F.
  • Cabin dimensions: length 12.6 ft.; width 7.7 ft.; height 4.5 ft.; volume 396 cubic feet.

 

Production History
The first production UH-60M was delivered to the Army on July 31, 2006 as production of the UH-60L stared to taper off. The multi-year-7 contract to Sikorsky Aircraft, awarded in 2007, included production of the Mike model for the next five years. In July 2011, Sikorsky had delivered the 300th UH-60M to the U.S. Army. The total quantity of UH-60Ms to be produced for the Army is expected to be approximately 1200 units.

Related Models
The chart below illustrates the many US and foreign military Black Hawk models that are related to the UH-60M. The Army HH-60M Medivac version was the first derivative of the Mike model. Besides the US Army, primary users of this model include

S-70A (UH-60M) -7

Additional Information Sources
Additional program background and technical information can be found in the book entitled “Black Hawk, the Story of a World Class Helicopter” published by the American Institute of Aeronautic and Astronautics in 2007 and written by Ray D. Leoni. ISBN-13:987-1-56347-918-2.

Prepared by Ray Leoni November 2011

 

 

for Additional reading see NEWSLETTER JULY 2013
and
NEWSLETTER JULY 2012

 

LAST UPDATE MARCH 25,

 

 
   
 
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