With increasingly short supplies of crude oil, serious consideration must be given to the substitution of other raw materials from which aviation fuels can be derived. Accordingly we are investigating the characteristics of kerosenetype fuels derived from oil shales, tar sands and coal. Other possible fuels such as methanol or methanol/JP blends may also be investigated. We are studying the effects of these potential fuels in engines and propulsion systems, as well as the potential for broadening current jet fuel specifications to achieve greater yield of fuels from feed stocks and to accommodate a broad variety of fuel supply conditions. The fuel characterization program will include laboratory and burner tests, followed by full-scale engine tests. The program is being planned and coordinated with the Department of Defense, the aerospace and airlines industries and fuel suppliers. The characterization project will be most useful to those concerned with policy decisions on alternative fuels production and allocation.

We do not plan further investigations of cryogenic liquid methane and liquid hydrogen in engines. Previous tests show that only minimum engine modifications would be needed to utilize these fuels. In our view, overall system considerations are the more significant issues to be studied. They include the design impact on both the airborne and ground systems, ground handling and operational problems, and the all-important issues of energy effectiveness, availability and economics. If at some future time cryogenic hydrogen or methane are needed for aviation use, the propulsion technology to accommodate them can be developed rapidly.

Our second near-term fuel conservation project studies the feasibility of applying certain advanced technology concepts to existing engines to improve fuel

consumption without requiring major redesign. For example, advanced concepts for compressor and turbine shaft seals demonstrated in laboratory tests in recent years can reduce air leakage, and might therefore reduce fuel consumption by as much as two percent. We are exploring with industry whether such seals can be retrofitted to certain existing engines. Another example is clean combustors, which may reduce fuel consumption at low power and idle settings because of improved combustion efficiency. The feasibility of incorporating these improved combustion chamber design features in certain existing engine types will be studied this year.

Component performance improvement.-Our program encompasses all components of gas turbine engine propulsion systems: inlets, fans and compressors, combustors and thrust augmentors, turbines, exhaust nozzles, high speed bearings, shafts and seals.

Our fan and axial flow compressor work is investigating advanced blade shapes for higher stage pressure ratios without sacrificing efficiency or stall margin. Progress in this has encouraged us to begin an experimental advanced multistage axial compressor, as I have previously described. Figure (8) shows a precursor experimental five stage compressor designed to achieve an overall pressure ratio of 9.1 to 1. Current design practice requires about eight stages to achieve this same compression.

Our principal research on turbines has the objective of achieving greater mechanical work extraction in each turbine stage than current design practice. Optimum turbine blade configurations for heat transfer and aerodynamic performance are also being sought for applications at 3500° F and 40 atmospheres pressure. As with compressors, reducing the number of turbine stages pays off in reduced engine and aircraft weight and improved fuel economy.

Engine system research.--Development costs required to bring a new engine from preliminary design into service status are enormous, running several hundred million dollars. One reason for high costs is an inability to predict all the

system interactions and subtleties of high performance propulsion systems over a wide variety of operating conditions, particularly in a dynamic environment. An important addition to our engine systems research is a new long-term fullscale engine research program jointly with the Air Force. In this program the Air Force will provide the Lewis Research Center modern advanced technology engines developed under Air Force programs, and jointly establish research program objectives and plans with NASA. The research objectives for the first engine soon to enter tests relate primarily to fan aeroelastic behavior, fuel controls and afterburning characteristics.

In summary, I have described for you certain highlights and new features of our advanced propulsion research and development programs to indicate the broad scope of the program and illustrate its objectives. The achievement of all these objectives-noise and pollution reduction, performance improvement, and energy conservation-is vital to the future health of aviation and to the welfare of our society in which aviation has become such an important factor. Mr. George Cherry, Deputy Associate Administrator, is here and we would be pleased to hear from you now.

STATEMENT OF GEORGE W. CHERRY, NASA

Mr. CHERRY. Mr. Chairman and members of the subcommittee, when I testified before you last year on short-haul air transportation, the primary problems I discussed were air traffic congestion and aircraft noise. Today, these problems still exist; in addition, the energy crisis and shortages of fuel for transportation have emerged as new problems. These problems challenge NASA to provide technology for shorthaul aircraft which can operate quietly from airports and runways which will supplement the capacity of our present airport and airway system. The obvious technical requirement also exists to provide this increased airport and airway capacity with a net reduction in the total transportation fuel required.

Other obvious requirements exist for the new short-haul system: the travelers must find it attractive so that they will use the new system which reduces congestion and saves transportation fuel; the operators must find it profitable to offer the service; and a point which cannot be overemphasized-the communities must find the operations completely acceptable environmentally so that they will permit the necessary ground facilities to be built or used.

I am glad to report that our technology programs are directed to solving both the older problems of air traffic congestion and noise and the newer problems of fuel shortages and increases in fuel costs. We believe the technology can satisfy the additional essential requirements of the travelers, the operators and the communities.

Despite its substantially greater speed, the modern civil transport aircraft today provides about the same number of actual passenger miles per gallon of fuel as the automobile (figure 1), approximately 29 passenger miles per gallon for the airplane and 28 passenger miles per gallon for the car. That is for typical load factors over distances of about 300 miles or greater. It is important to compare the airplane with the automobile because about 85 percent of all short-haul intercity travel over 100 miles is by private automobile. Obviously, any transportation mode that will make a significant contribution to fuel conservation must therefore compare favorably to the automobile in respect to both fuel consumption and traveler convenience.

As we look to the future, we see that improvements in short-haul air transportation will permit even more favorable energy comparisons with automobile transportation while retaining significant time-saving advantages. The following additional fuel savings can materialize.

The first way is through increases in airplane load factors. This method can, of course, be implemented today. If the airplane load factor is increased from 55 percent to 70 percent, the modern airplane provides about 37 actual passenger miles per gallon of fuel, a greater than 30 percent improvement over the 28 passenger miles per gallon cited for the automobile.

Mr. THORNTON. Is the 28 passenger miles per gallon based upon the statistical number of passengers riding in automobiles or is that an assumed figure?

Mr. CHERRY. Yes, sir, it is based on the statistical number of passengers riding in automobiles; the data were obtained by the Department of Transportation.

Mr. THORNTON. That is, two passengers per vehicle?

Mr. CHERRY. I believe that is what it turns out to be.

Mr. THORNTON. Excuse me for interrupting. Please continue. Mr. CHERRY. Many short-haul travelers will continue to try to travel by automobile, especially when traveling in small groups or families. The business traveler or pleasure traveler traveling alone are the most likely candidates to divert to air transportation. Comparing the modern airplane at 70-percent load factor to the automobile carrying a solitary traveler, we see a very considerable saving in energy-37

passenger miles per gallon for the airplane, compared to about 15 passenger miles or even less to the gallon for the car, an improvement of the airplane over the single passenger car of almost 150 percent.

The second way of saving fuel by short-haul air transportation is through specialized aircraft more efficiently configured for the shortduration trip. The Boeing 747SR short-range version of the B-747 is a step in this direction. The B-747SR yields about 26 percent more available passenger miles per gallon that the B-474.

The third way of saving fuel by short-haul air transportation is through advanced technology. The NASA program will provide advanced technology for very fuel-efficient, very quiet aircraft which can operate from airport sites close to major transportation demand centers by the early or mid-1980's. The proximity of the short-haul sites to the travelers' origin and destination points will decrease the fuel as well as the travel time used by travelers in getting to and from the airport. Therefore, the conveniently located short-haul airports decrease the travelers total door-to-door trip time.

The technology required for the conveniently located short-haul airports includes the very quiet engine technology being developed in the Quiet Clean Short Haul Experimental Engine (QCSEE) program, the propulsive-lift technology being developed by our R. & T. efforts in the laboratory, and our flight experiments in the future with the Quiet Short-Haul Research Aircraft (QSRA).

The technology advancements from composite materials for lightweight structures, from the QCSEE propulsion advances to reduce engine specific fuel consumption, and from improved aerodynamics to reduce drag, can all contribute significantly to the reduction in fuel consumption of future short-haul aircraft. Adding up the effects of increased load factor, short-haul aircraft specialization, and reduced weight and reduced drag due to the advanced technology, we foresee the future short-haul aircraft providing at least 64 passenger miles per gallon.

It is important to consider the impact of fuel costs on foreign sales of U.S. aircraft. Our foreign customers for aircraft sales, especially in Europe and Japan, are even more sensitive than we to fuel costs because of their greater dependence on imported petroleum products. For this reason, aircraft of low fuel consumption will have a significant advantage in the foreign market-place.

Many airports suitable for short-haul air traffic already exist and could be used if aircraft capable of quiet take-off and landing from short runways were available. The number of airports that can accept short-haul aircraft increases as the noise footprint of these aircraft is reduced. For example, if the noise footprint could be reduced by a factor of 10, the number of airports that could completely contain the noise footprint increases by a factor of three (figure 2).

Current aircraft are unsuitable for such airports because of the long runways they require and because they create noise patterns that impact on large areas of the community adjacent to the airport.

Another important factor in using separate airports for short-haul traffic is congestion relief at the major conventional takeoff and landing hub airports.