FIGURE 5.-NASA aeronautics R. & T. users

CIVIL AVIATION

Private industry: Manufacturers, airlines, and private pilots.
Government: DOT, FAA, airport authorities.

MILITARY AVIATION

DOD: Air Force, Navy, and Army.

The kind of people we seek to influence with our aeronautical technology are characterized as the users of our technology shown on the next chart. These users consist of a substantial segment of people in private industry, airframe and propulsion system manufacturers, and airlines who use the vehicles which incorporates the technology and, of course, the private pilot community which uses general aviation aircraft which also benefit from our technology.

In addition, other users of our technology are other segments of the Government, particularly the DOT and FAA and the various local airport authorities. On the military side the prime users are in DODthe Air Force, Army, and Navy.

It is these users with whom we interact in order to keep them aware of our technology advances and also to plan where we should go in the future.

I would like to summarize a couple of examples of technological advances that have occurred as a result of NACA, the predecessor organization to NASA, and NASA aeronautical research and technology activities.

I have selected six of these contributions to talk about. They are shown on this chart and I am going to step through them individually. The first one of these is called the NACA cowling.

In the early days of aircraft, engines were exposed to the free stream of the air passing over the vehicle. There was a problem with distributing that air properly in order to cool the engine, so they would have a reasonable lifetime especially as engines became more and more powerful, which was the key to early development of aircraft in this country.

The researchers at Langley worked on the concept of putting a wrapper or cowling over the engine, which resulted in not only reduced drag but also enabled more efficient distribution of cooling air throughout the engine leading to long life and the possibility of more powerful engines.

The number of vehicles which benefited from the cowling concept as developed by NACA was very numerous. A couple of outstanding military applications of the concept are shown on the left side of the figure and several outstanding civil applications of the concept shown on the right. As is indeed the case in most of these technological advances, they quickly become incorporated into the catalog of design features of airplanes and shortly practically all aircraft used the cowling concept and the other concepts I am going to be talking about.

The second item is the concept of the swept wing. The swept wing was critical to the development of the high-speed airplane. This is also a typical development in that it was not solely a NACA development, but it was a development which truly was international in character and also cut across industry, Government, and university lines in the development of the concept. However, I have pointed it out here as a NACA contribution because NACA truly did have a leadership role in the development of the swept wing concept.

Of course. the swept wing is critical to high-speed flight so it quickly appeared on all high-speed airplanes, both military and civil. Today, only very low speed airplanes have wings which are not swept to a marked degree.

The third contribution I would like to talk about is the area rule. Dick Whitcomb and his staff at Langley were working on the problem of high-speed drag in the early 1950's and came up with the concept of what is loosely known as the area rule. This concept was indeed the secret to drag reduction and enabled acceleration to supersonic. speeds in the early fighter aircraft that the United States developed in the mid-1950's, the so-called Century eries. It also found its way into application in civil aircraft. It was employed on the Convair-990, as shown on the right-hand slide of the figure, and was an important design feature of the U.S. supersonic transport while that vehicle was under development.

I have talked about airframe contributions.

I would like to talk now about propulsion system technology contribution. This grew out of work at the Lewis Research Center at Cleveland. The concept of the transonic compressor. In the early days of gas turbine engine development, it was thought that one had to maintain the relative flow over compressor blades at essentially subsonic speeds. This limited the pressure ratio that could be developed by a compressor and therefore resulted in compressors being much larger than they now have to be. The Lewis people pioneered the work on transonic compressor blades, and now there is not a jet engine made in the United States that doesn't have transonic compressor blades

based on the NACA technology in it. Some of the specific examples are shown in the figure.

The next item that I would like to talk about is that of the variable sweep wing. This grew out of the wind tunnel work again at Langley Research Center in about 1958, just about the time we were making the transition from NACA to NASA.

This concept got its first application in the F-111 then in the F-14 and is a significant design feature of the B-1 bomber. It was well recognized that for this type of aircraft what one really wanted was two different kinds of wing sweep, a relatively high aspect ratio unswept wing for low-speed and a highly swept wing for high-speed performance. The contribution here was to show how this could be achieved with a reasonable mechanical system while still maintaining a reasonably smooth configuration which satisfied both subsonic and supersonic aerodynamic requirements.

The last historical contribution that I would like to talk about is the supercritical wing. The supercritical wing also came out of the research group at Langley headed by Dick Whitcomb, and was developed in about 1965. Therefore it is only about 10 or 11 years old, so it is not yet flying on any production aircraft. However, it is a design feature on both the Boeing and Douglas versions of the Air Force Advanced Medium STOL Transports (AMST). We feel sure that the supercritical wing section will be used on any future transport vehicle.

The kinds of things we do require some rather specific capabilities and facilities.