Drucella Andersen
Headquarters, Washington, D.C.                                           
February 9, 1993
(Phone:  202/358-4701)

Michael Mewhinney
Ames Research Center, Mountain View, Calif.
(Phone:  415/604-9000)


RELEASE:  94-21

NASA-ARMY RESEARCH PAVES WAY FOR BETTER HELICOPTERS

     Future helicopters will be quieter and more efficient 
thanks to data from hundreds of hours of test flights during a 
10-year NASA-Army research program.

     Launched in 1984, the UH-60 Airloads Program at NASA's 
Ames Research Center, Mountain View, Calif., studied helicopter 
rotor vibration, noise, motion and airflows.  The $6 million 
project, which will conclude this month, gives engineers 
information they need to develop new helicopters and improve 
existing designs more quickly and cheaply.

     "We've gathered a huge data base for the helicopter 
industry and the academic world to help refine the ability to 
design helicopters and predict their performance," said Ames 
Project Manager Paul Loschke.  "If you stored all our data on 
those little floppy computer disks, the stack of disks would be 
570 feet high; that's taller than the Washington Monument."

     "Industry is always pleased to have the support of NASA 
research -- it's the wave of the future," said Rhett Flater, 
Executive Director of the American Helicopter Society, 
Alexandria, Va.  "The transfer of data will be extremely useful 
to the rotorcraft community."

     Bill Bousman, the project's principal investigator, noted 
that radical designs come along infrequently.  When a new 
concept does look attractive, engineers need analytical tools 
to reduce rotor noise and vibration -- factors that affect 
passenger comfort and maintenance.


                                                      -more-

                                                         -2-


     "The real excitement in designing helicopters is how to 
make them quieter, better and cheaper to build and operate," 
Bousman said.  "The big payoff is in reducing risk and cost." 

     The NASA-Army research used an Army UH-60 Black Hawk built 
by Sikorsky Aircraft Co., a division of United Technologies 
Corp., Stratford, Conn.  The $5 million helicopter can carry 10 
passengers.  The Army used the UH-60 to transport troops during 
Operation Desert Storm and in Somalia. 
 
      "The Black Hawk is very representative of a modern 
helicopter, and it was easy and less costly to get parts from 
the Army," Loschke said.  

     Sikorsky engineers built two specially designed 
instrumented rotor blades for the UH-60 Airloads Program.  One 
blade had 242 pressure sensors to measure airloads along the 
blade.  The second blade had instruments to measure the 
structural response to airloads and other aerodynamic 
conditions affecting the rotors. 

     "Airloads" are the forces on the rotor blades imparted by 
lift -- the upward force produced as the blades turn.  Ames 
engineers studied how those forces and pressures affect a 
helicopter's performance, efficiency and noise. 

     "For example, when the blade is spinning around, it is 
generating lift and producing various noises like the popping 
sound you hear when a helicopter hovers," said Loschke.  "The 
data from the program will help us better understand that 
phenomenon."

     To record the flight test data, Ames developed special 
data acquisition systems mounted atop the rotor hub and in the 
cabin.  Later, the data was put onto 5-inch optical laser disks 
in a "jukebox" computer storage system.  Engineers and 
helicopter designers will be able to access the stored data by 
telephone with a computer modem.

                                                  -end-

NOTE TO EDITORS: A video clip of the UH-60 research is 
available to media by calling 202/358-1734.  Still photos also 
are available, 202/358-1900

Color:                          B&W:

94-HC-33, -34        94-H-36, -37