Technology assessment of advanced general aviation aircraft

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NASA CR-114338 TECHNOLOGY ASSESSMENT OF ADVANCED GENERAL AVIATION AIRCRJ.FT I SUMMARY REPORT June, 19i1 Distribution of this report is provided in the interest of info-^ma.tion exchange. Responsibility for the contents resides in the author or organization that prepared it.

Prepared under Contract No. NAS2 -5972 by C. H. Hurka.mp, W. M. Johnston, and J. H. Wilson The Advanced Concepts Department LOCKHEED-GEORGIA COMPANY Marietta, Georgia

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NASA CR-114338 TECHNOLOGY ASSESSMEL`iT Of ADVANCED GLM - MAL AVIATION AIRCPJ.r'T SUMMARY RI,,f'ORT June, 1911 Distribution of this report is provided in the interest of Responsibility for the contents information exchange.

resides in the author or organization that prepared it.

Prepared under Contract No. NAS2 -5972 by C. H. Hurkemp, 1d. M. Johnston, and J. H. Wilson The Advanced Concepts Department LOCH-GEORGIA COMPANY Marietta, Georgia P FOR Advanced Concepts and Missions Division Office of Advanced Research and Technology National Aeronautics and Space Administration Ames Research Center Moffett Field, California

FOREWORD between the National Aeronautics and Space Administration -5972 Contract NAS2 and the Lockheed-Georgia Company, effective 15 June 1970, provided for the Y assessment of the impact of advanced technology applicable to general aviation time frame and for recommendations for aldit.onal research aircraft for the 1985 economy of general aviation.

the safety, utility, and areas which may increase by the Advanced Concepts and Mission The work reported herein was sponsored Technology, Mr. Thomas L.

Division of the Office of Advanced Research and Galloway, NASA study monitor.

the Lockheed-Georgia Company under this contract was the responsi- The work at bility of the Chief Preliminary Design Engineer, Dr. W. C. J. Garrard, and of the Advanced Concepts Department, Mr. It. H. Lunge, Manager.

This report summarizes the work performed in fulfillment of the above contract.

FABLE OF CONTENTS Section loo. Pale No. Title 1.1 1-1 Introduction 1.2 1-2 Acknowledgements 1.3 l-3 Scope of Study 1.4 1-4 Requirement & Constraints 1.5 1 -5 Technology Investigation 1.5.1 1 -5 Aerodynamic Design 1.5.2 Propulsion Technology 1-7 1-10 Structure and Materials J.. 5.3 1.5.4 1-11 Avionics, Instrumentation and Flight Control Landing Gear 1.5.5 1-12 1.5.6 1-13 Functional Subsystems 1.5.7 1-14 Utility and Convenience Features 1.5.8 1-14 Safety Considerations 1-15 VTOL Technology 1..5.9 1.6 1-16 Selection of Baseline Designs 1.7 1-19 Parametric Analysis Methodology 1.7.1 1-19 1.7.2 1-22 Results and Baseline Configurations 1.8 1-28 Sensitivity Analyses 1.8.1 1-28 General Procedure 1-28 Advanced Technology Baseline Design 1.8.2 1.8.3 1-32 Alternate Configurations 1.8.4 1 -33 Advanced Avionics and Subsystems 1.8.5 1 -37 Performance Variables 1.8.6 Increased Production 1-40 1.8.7 1-41 Sensitivity Summary 1.9 1-42 Recommended Configurations 1.9.1 1-42 Category I 1.9.2 Category II 1--43 1.9.3 Category III 1-44 1.9,4 1-46 Category IV 1.10 1 Projection of General Aviation Use Potential -47 1.10.1 Price/Quantity Relationship 1 -47 1-48 Growth Constraints 1.10.2 1.11 1 -48 Conclusions 1.11.1 Specific Conclusions 1-48 1.11.2 General Conclusions 1-49 1.12 Recommendations 1-50 Aircraft Research and Development 2-12.1 1-50 1.12.2 Propulsion Research and Development 1-50 1.12.3 General Aviation Non--Technical Constraint Studies 1-51 References 1-51 (a)

' j ; rbG INDEX Title Figure No. Page too.

1.3.1 study Plan 1-3 1.4.1 Summary of Baseline Design Requirements 1-4 Engine Matrix 1.5.1 1-7 1.5.2 Comparative Propulsor Performance 1-8 1.5.3 Propeller R.P.M. for Seventy-Five PNdb Noise bevel 1-9 Specific Tensile Strength vs. Specific Tensile 1-9 1.5.4 Modulus of Composites 1-10 Systems Classification 1.5.5 1-11 1.5.6 Soil Strength Required to Support ,Overpressure 1-12 1.5.7 ACLS Typical Trunk Plenum 1-13 1 -15 1.5.8 Vertical Lift Capability vs. Disc. Loading _. 1.'6.1 Cate-gory I Candidates 1-16 1.6.2 Category II Candidates 1-17 1.6.3 Category III Propeller Candidates 1-18 1.6.4 Category IV Candidates 1-18 1.7.1 Parametric Flow Diagram 1-19 s 1.7.2 Price Trend of General Avia'i.on Aircraft with ti Weight-Speed product 1-20 1.7.3 Operating Cost Factors Summary 1-21 q Aircraft - Mile Cost Trend with Utilization 1-21 1.7.4 Category I Parametric Analysis Results 1-22 1.7.5 Category I Baseline Aircraft 1.7.6 General Arrangement. 1-23 Category II Parametric Analysis Results 1-24 1.7.7 a, 1.7.8 General Arrangement Category II Baseline Aircraft 1-25 Category III Parametric Analysis Results 1-26 1.7.9 General Arrangement Category III Baseline Aircraft 1-26 1.7.10 1.7.11 Category IV Parametric Analysis Results 1-27 1.7.12 General Arrangement Category IV Baseline Aircraft 1-27 1-28 1.8.1 Sensitivity Analysis Procedure 1-28 1.8.2 Effect of Advanced Propulsion , Materials 1-29 1.8.3 Effect of Advanced 1.8.4 Combined Effect of Advanced Propulsion and Materials 1-29 General Arrangement: Category I Advanced Technology 1.8,5 Aircraft 1-30 General Arrangement: Category II Advanced Technology 1.8.6 t^ Aircraft 1-30 Category III Advanced Technology General Arrangement: 1,8.7 Aircraft 1-31 Category IV Advanced Technology 1.8.8 General Arrangement: Aircraft 1-31 Foldable Wings and 1.8.9 _ Category I Comparison: l: Roadability 1 -32 Category II Comparison: Fixed Wings vs. Autogyro 1-32 1.8.10 (b)

FIGURE INDEX Figure No. Title Page No.

1.8.11 General Arrangement Category III Turbofan Aircraft 1-34 1.8.12 Category III Comparison: Propellers vs. Turbofan 1-34 Effect of Advanced Avionics and Automatic Flight 1.8.14 Controls 1-35 1.8.15 Effect of Extra Safety Provisions 1-36 1.8.16 Effect of Pressurization and High Altitude Cruise 1-36 1.8.17 Effect of Noise Level on Price 1-37 Effect of Field Length on Price 1-37 1.8.18 1.8.19 Effect of Cruise Speed on Price 1-38 1.8.20 Ef:^ect of Cruise Speed on Operating Cost 1-38 1.8.21 Effect of Cruise Range on Price 1-38 1.8.22 Effect of Seating Capacity on Price and Seat - bile Cost 1-39 1.8.23 Effect of Yearly Production Rate on Price 1-40 1.8.24 Effect of Technology and Noise Levels on Price vs.

Weight - Speed Product 1-41 1.8.25 Effect of Added Provisions on Price vs. Weight - Speed Product 1-41 General Arrangement Category I Recommended 1.9.1 Configuration 1-42 Comparison Between Recommended and Baseline 1.9.2 Configurations, Category I 1-42 1.9.3 General Arrangement Category II Recommended Configuration 1-43 Comparison Between Recommended and Baseline 1.9.4 Configurations, Category II 1-43 1.9.5 General Arrangement Category III Recommended Configuration 1-44 1.9.6 Comparison Between Recommended and Baseline Configurations, Category III 1-45 Comparison Between Recommended and Baseline ^.

1.9.7 Configurations, Category IV 1-46 =' 1.10.1 Past and Projected General Aviation Aircraft Deliveries Per Year 1-447 1.10.2 Price Classifications of General Avfi--^tion Aircraft Delivered in 1969 and Their Relationship to Categories I, II, and III 1-47 t 1.12.1 Recommended Aircraft - R&D Areas 1-50 Recommended Propulsion Avieon es - R&D Areas 1.12.2 1-50 General Aviation Non-Technical Constraint Studies 1.12.3 1-57 F (a)

1.1 Introduction NASA studies of possible short-haul trans portation have shown that general aviation has the potential of performing an inoreasingly important role in the natione;l transportation system (Reference 1.1). In order to realize this potential fully, the cost, performance, and operational characteristics of this class of aircraft must be improved. NASA, through in-house and contractual studies, is attempting to identify critical technology areas where additional research may increasi the safety, utility, and economy of general aviation.

(See Reference 1.2.) The intent of the present study is to assess the impact of advanced technology applicable to general aviation aircraft for the 1965 time frame. An important facet of the study is to relate the influence of advanced technology and new design philosophies on the c.st, performance, and operational capabilities of this class of aircraft. The four categories include conventional, and V'/STOL performance in 4 to 9 place airoraft, STIOL with helicopters included in the study. The study procedure consists of: establishing an optimized design configuration in each category, based on present technology; investigating and pinpointing the most promising areas of applicable (b) technology; r (c) applying the selected advanced technology to each of the present technology designs; (d) assessing the results and making recommendations for additional research.

The areas of advanced technology include those of aerodynamics, propulsion, structural materials, avionics, flight safety, automatic control, noise and emission abatement. These are assessed individually and in combination by means of a computerized analysis. The recommended combinations are then studied to determine their potential impact on the overall transportation system, after which the areas of technical support are recommended. This report comprises a summary of the study program. A more complete treatment is contained in Reference 1.3, the Final Report.

that the final results of the study, in the form of It should be emphasized recommended configurations in each of the four categories specified by NASA, indicate long range potential and not predictions. In order to help develop extensive government support is required in the areas of this potential, technology research and development, the expansion of small airfields, pilot and other educational programp.

training assistance 1-1

1.2 j,,,.^,1=aw lodgement s The Lookheed-Georgia Company study team was led by C. H. Hurkamp, under the direction of R. H. Lange, Manager, Advanced Concepts Department. The study team comprised the following members: W, M. Johnston . . . . Aerodynamic Analysis H. E. Schmitt . . .

Propulsion Analysis D. F. Glover, Jr. . . . Weight Analysis J. H. Wilson . . . . Cost Analysis B. E. Montgomery . . Avionics Technology J. M. Eaton. . . .

. Conceptual Design N. R. Daigle . . . . Computer Programming • R. Vick. . . . . . Computer Programming • A. W. Mooney . . . . . Program Consultant Advisory service was rendered by X. H. Wilson, Reliability Division Engineer, Lookheed - Georgia Company, A. R. Yackle, Assistant Division Engineer (Rotary Wing), Lockheed - California Company, and W. M. Hawkins, Nice - President, Science & Engineering, Lockheed Aircraft Corporation. The investigators wish to acknow- ledge, with thanks, direct contributions received from the following Lndividuals and organizations: Mr. Carl Rohrbach, Hamilton Standard Division, United Aircraft Corp.

Mr. David Biermann, Hartsell Propeller Company Mr. M. K. Schleich, McCauley Industrial Corporation Dr. R. S. Roes, Goodyear Aerospace Corporation Messrs. R. S. Kelso.. and George Cash, Cornell Aeronautical Laboratory Mr. J. H. Simmons, Piper Aircraft Corp., Vero Beach, Florida Mr. D. R. Ellis ( Mgr., Flying Qualities Research) Princeton University Mr. E. R. Hinz, The Aerospace Corporation Mr. R. B. Lightfoot, Sikorsky Aircraft Division, United Aircraft Corporation Mr. R. L. Lichten Bell Helicopter Company Wright Corporation Messrs H. Allen and R. Leisenring, Curtiss - Mr. H. D. Cox, Teledyne Continental Motors Messrs. R. L. rummings and H. Gold, Lewis Research Center, RASA Messrs. Schen"aly, Griffith, Paul and Roberts; Lockheed Missiles and Space Co.

Dr. K. H. Digges, Air Farce Flight Dynamics Laobratory Mr. J. L. Church.11 $ Collins Radio Company Mr. V. J. Kayne, Aircraft Owners and Pilots Association Mr. J. W. Bail, Naroo Avionics Mr. A. R. Applegarth, Aradar Corp.

The investigators also wish to acknowledge their appreciation of the assistance rendered by the NASA Study Monitor, Mr. T. L. Galloway, during the entire study and in the preparation of this report.

1-2

FIGURE 1,3«I STUDY PLAN TECHNOLOGY INVESTIGATION.

CATEGORIES AN D PROJECTION 2 CANDIDATES IN EACH PARAMETRIC ,ANALYSIS • OPTIMIZE • COMPARE • SELECT 1 PER CATEGORY • TECHNOLOGY APPLICATIONS • PERFO` DANCE • PERFORMANCE VARIABLES . SAFETY • SAfLTY FEATURES ' SALES APPEAL AFFECSIING • UTILITYjCONVENIENCE FEATURES • COMMUNI PY ACCEPTAKE • GROW TH FACTORS • PRICE d OPERATING COST

=1--

RECOMMENDA11ONS • SELECT BEST 1985 CONFIGURATIONS IN EACH CATEGORY • LIST POTENTIAL RESFARCH AREAS FOR NASA 1.^ Scope of' Study 1.4 and 1.5 of The study follows the guidelines and constraints of paragraphs the Statement of Work in Reference 1.4. This dooument, which formed part of the R.FP for this study, was interpreted by the Contractor in his Technical Proposal, Lockheed-Georgia Company Report ETP 943. The overall scope is illustrated in the Study Flow Diagram, Figure 1.3.1.

The first step of establishing requirements is to identify the constraints imposed by the RVP along with FAA requirements and any modifications agreed upon by the contractor and NASA. The second step is the identification of the projected r,plic+able technology, in each of the areas listed, by specialized engineering personnel in each discipline and with the aid of published reference data and consultation with cognizant representatives of NASA, Lockheed and other organizations in the fields of airframe, engine, materials, avionics and appli- cable subsystems. In the third step, the most appropriate lines of technological development are selected for application to the sensitivity analysis. The fourth step is that in which two or more candidate configurations are invest{- gated for each of the four specified categories. These configurations are then optimized by the use of parametric programs, using initial and operating cost as criteria. Present state-of-the-art is applied so that a base can be established for advanced technology sensitivity analysis.

In the fifth step, the candidate configurations within each category are compared, and one or more out of each is selected for sensitivity studies.

The sixth step consists of applying variable characteristics to the selected configurations to determine the effectiveness of each variable toward improving the desired characteristics. These variables fall under five headings: Tech- nology, Safety, Environmental Performance and Growth. For each technology variable the future state-of-the-art is related to that of the present, so that its effect on the characteristics listed can be determined. Tha results of the sensitivity studies are then examined to determine optimum combinations and to recommend a selected future configuration in each category.

Finally, the last step fulfills the principal purpose of the study by de- fining the recommended areas of study, research and development recommended to apsist in promoting technology which w l l enhance the future growth of general aviation.

FIGURE 1.4.1 SUMMARY OF BASELINE DESIGN REQUIREMENTS r.r..^ a..^i.r.^^^.r^...,.........M.w^...........g^.^^.nr..ri^irirr...ui.r.h.r.r...

CATEGORY 111 1 11 IV CRITICAL FIELD LENGTH (FT.) 1000 ;500 1500 VTOL RANGE (STAT. MILES) 500 500 1500 CRUISE SPEED (KNOTS) 130 200 150 25 0 MIN. NO. OF SEATS 4 4 b 4 I COMMON REQUIREM ENTS 75 PN6, AT 500 FT.

EXTERIOR NOISE LEVEL WEIGHT ALLOWANCE PER SEAT 220 LBS. (INCLUDING BAGGAGE) FUEL RESERVE 45 MIN.

t 1.4 Requirements and Constraints Constraints and. guidelines for the study were imposed by NASA in the Specifi- cation referred to in Section 1.3 and are briefly summarized belowt ° Use advanced technology applicable to the 1985 time period (this was applied which reflect in the sensitivity analyses to the 'baseline configurations present technology).

° Apply the results of previous and current applicable studies.

° Apply FAA regulations, point ouu restrictions or inadequacies, or use industry- accepted criteria.

° Limit the external noise level to 75 PNdb at 500 ft.

Assess the effect of annual production rate on aircraft cost.

° Express costs in 1 969 dollars (1970 was adopi-ed).

0t performance requirements with aircraf* fu^7y landed (2 201bs per

passenger including baggage.)

Meet specified extra safety requirements (assessed separately in the sensi- tivity analyses).

° Calculate operating cost for three levels of yearly utilization 000, 300 and 500 hours) Table 1.4.1 shows the minimum performance requirements specified for each category of aircraft investigated. These requirements were subjected to sensi- tivity analyses, which are reported in Section I.B.

1-4

1.5 Toohnoloa Investigation This portion of the study covers an examination of present and emerging tech- nology in the disciplines ;governing the design of aircraft in each of the four categories. They include aerodynamics, propulsion, structure and materials, avionics, landing gear, functional subsystems, safety techniques, utility and convenience features, and VTOL technology.

1.5.1 Aerodynamic Design Aerodynamic technology investigation covers the areas of high lift systems, drag configuration and stability and control considerations, which will be discussed in that order.

Appropriate non-augmented high lift systems, resulting from NASA research, were investigated for application to the four aircraft categories of this study. Two types were selected for parametric analysis: o The single slotted flap, identified as 2h in NACCA TR 664, appropriate for airplanes in Categories I and III.

The double slotted type flap reported in NACA TR 723, appropriate for air- o planes in Category II, in combination with dropped ailerons of similar shape to that of the single slotted flap.

their complication and atten- Augmented systems were not considered because of dant high cost. They would only be appropriate to the STOL airplanes in Category II. These, however, are single engined and minimum flight speed based on would haver to be the power-off condition..

new technology is available for the application of drag reduction, other No than that of applying the tried and true principles of good aerodynamic design.

This includes proper streamlining of the fuselage and the avoidance of bad interference effects at the junctures of principal components, such as the wing-fuselage intersection.

Pusher propeller configurations are included in the Category I and II appli- cations. Previous examples in the general aviation industry have proven to result in abnormally high drag, due to maintaining a short length of fuselage between the full-width cross-seu Lion and the propeller spinner. The examples investigated in this study employ extension shafting between the engine and propeller. The fuselage itself is faired to a two- dimensional wedge in the vertical plane, with a superimposed streamlined body, connecting the air induction a000p and the propeller spinner faired in the horizontal plane.

This method is believed tc result in drag comparable to that of a well-designed propeller airplane, since it is not subject to slipstream impingement.

txaotor Both fixed and retractable landing gear were investigated for Category I, while the other three categories use retractable gear.

1-5

was made of longitudinal stability and control character- A brief investigation istics to determine the most appropriate horizontal tail, configuration and center of gravity limits. It was concluded that the combination of a variable incidence stabiliser with a single slotted elevator requires the lowest ratio of horizontal tail area to wing area, being about half that of the conventional fixed stabilizer with an unslotted elevator. The combination of a "flying tail"

with an anti-boost tab conventional practice, but is not

is somewhat better than as effective as the recommended configuration and has other disadvantages, such as increased susceptibility to flutter and lowered level of safety in the event of a failure of the longitudinal control system. With a pusher propeller installation, the rearmost C.G. position mint be well forward along the M.A.C.

in order to minimize tail size. A usable C.G. travel of 15% of the M.A.C. is recommended.

The aerodynamic inputs to the computer are the zero lift drag, high lift oharacteriatics, and proper induced drag constants. The zero lift drag is based on flight cruise speed, wing and tail thickness ratios, fuselage geometry, and special configuration characteristics. The flap characteristics are barred on NASA data, and a wing efficiency factor of 0.8 is used for determination of induced drag.

-,.

i .

1-6

FIGURE 1 .5.1 ENGINE MATRIX I SHAFT ENGINE -GEAR I i JET ENGINE I GAS DRIVEN FAN OR ROTOR j DRIVEN PROPELLER OR ROTOR • • TURBO FAN JET TURBO ENGINES COMPOUND I GAS (BRAYTON CYCLE) FAN JET - TIP JET ROTOR I HYBRID ENGINES VAPOR (RANKINE CYCLE) DISPLACEMENT FREE PISTON-TURBINE ENGINES O CONVENTIONAL PISTON I GUIDED PISTON-TURBINE ENGINES I WANKEL ENGINE (ROTATING COMBUSTOR) OTHER TYPES ^i 1.5.2 Propulsion Technology categories: The investigation of this subject is divided into the following o Engine Types o Propulsors o Propeller Technology o Engine Emission of Pollutants o Propulsion Noise The investigation scope of engine types covers those marked with black circles in the engine matrix diagram of Figure 1.5.1. The present level of technology indicates the superiority of the reciprocating engine for Category I aircraft with the turboshaft engine becoming a strong competitor in the other three categories. Looking ahead to 1985 9 however, there appears to be a great poten- tial for the rotating combustion enginep which has already appeared on the automotive scene and has been experimentally tested in aircraft.

1-7

FIGURE 1.5.2 LBS OF THRUST PER SHP 100 200 300 400 500 VEHICLE SPEED (KTS) Looking at propulsor technology, the propeller appears to be the most efficient type in the cruise speed range of 130 to 250 knots of interest to this study.

Nevertheless, the turbofan engine is competitive in Category III and the multi- another strong possibility.

blade, shrouded propeller (termed "prop-fan") is Figure 1.5.2 shows the relative effectiveness of propellers, prop-fans and turbofans in terms of thrust per horsepower at various speeds. However, since 'I high cruise speed is considered a desirable asset for business aircraft, the i turbofan has been evaluated against the rotating combustion engine/propeller r I combination in Category III.

serious in aircraft engines as The emission of po]!l Cants is not nearly as in i engines.

automotive Aircraft engines contribute less than 2 percent of the total emission pollution. Normal cruise at relatively lour fuel -air ratio results in low carbon monoxide emission. The only operating condit.t.ons in which carbon monoxide would be released are high power and idle operation, and this condition can be alleviated by the use of fuel injection. It is expected, however, that some special provision may eventually have to be made to reduce the amount of nitrogen compounds in exhaust gas during the next decade, but being done on this problem by automotive companies, and the much work is aircraft engine manufacturers could use the same techniques.

Technological advances in the propeller field have so far been restricted to propellers for large, high performance airplanes. They include development of the fiberglass/steel spar blade, integral reduction gearing and variable camber. Not only has the ratio of weight-to-shaft horsepower been steadily decreasing, but considerable p:dogress has been made in providing for fail- safe, easily maintained hardware. Hamilton-Standard's NASA-sponsored study (Reference 1.5) outlines several interesting approaches to simplified light- weight, low-cost propeller design appropriate to general aviation aircraft.

PROPELLER SPEED FOR 75 I..," FIGURE 1.5.3 PNDB NOISE LEVEL R.P.M. -., I T I I I I CAT. 1 225 H.P./1 PKOP FOR OTHER CONDITIONS - o DISC LOADING REMAINS CONSTANT o SLOPE OF RPM VS. DIAMETER THE SAME o DIAM. VARIES AS SQUARE ROOT OF H.P. REQ./H.P. ASSUPA D , CAT. 2 225 H.P 2 PROPS CAT. 3 ( At. 2 — - 350 H.P.jPROP "C 400 H.P.

2 PROPS PROP 8 9 11 12 13 PROPELLER DIAMETER -FT.

The noise level of piston and rotating combustion engines can be quieted below much the propeller noise level by reliable techniques. Turbofan engines are more difficult and the practical lower limit appears to be about 85 PNdB at 500 ft. A very considerable weight and cost penalty would accure as a result of reducing the noise level below this value.

Considerable study has been given, in the helicopter field, to the reduction of rotor noise. Effective techniques have included operation at tip speeds below 550 ft/sec, use of sound-absorbing materials in the engine compartment and application of trapezoidal or sweptback blade tips. This over-all treatment enough to assure meeting the study requirement of 75 PNdB at 500 ft, which is is particularly appropriate to helicopter operation in densely populated areas.

propeller performance with noise level has received con- The interrelation of siderable attention in this study. Variations of RPM with propeller diameter PNdB noise level at typical powers for the first three categories of for 75 In Categories I, II, and III, it has airplanes are shown in Figure 1.5.3.

been found feasible to install large diameter, slow-turning propellers which a high level of not only have a high static thrust-to-horspower ratio but also efficiency in cruise flight. The diameters required for Category I are not unreasonably large, but grow increasingly larger as the power requirements for Categories II and III increase. Propellers which meet the 75 PNdB noise level from 15 to 17 ft in diameter and require serious compromises in Category III are airplane. The methodology used in this study was developed in the design of the by Hamilton Standard in the previously mentioned study for NASA which was directed entirely at general aviation use. Quiet propeller operation has been successfully demonstrated, with the Lockheed Missiles and Space Company "Q-Star', and their Army-sponsored YO-3A airplanes.

1 -9

FIGURE 1.5.4 SPECIFIC TENSILE STRENGTH VS.

SPECIFIC TENSILE MODULUS OF COMPOSITES (IN DIRECTION OF FIBER ALIGNMENT) 6r s SYN. FIBER/EPDXY A GRAPHITE/EPDXY SPECIFIC TENSILE STRENGTH (106 IN.) BORON/EPDXY 3 11 GLASS/EPDXY STEEL, Ti, Mg O DALUMINUM • TEST POINTS SPECIFIC TENSILE MODULUS (10 8 IN.)

Structure and Materials

1.5.3

The application of advanced materials, structural design, and manufacturing techniques to general aviation aircraft has been investigated by San Diego Aircraft Engineering, Inc., in a previous NASA study (Reference 1.2).

Now structural material applicable to general aviation use include previously used and emerging composites. Glass fibers in a resin matrix have had limited aircraft employment to date, but this material is expected to be used with increasing frequency as new fabrication pr ceases come into being. Much higher strength-to-weight composites, such as graphite, boron and a new synthetic fiber, all used in an epoxy matrix, wi-'%;h desired directional alignment, are in the research and development stage. They are expected to become available time period when the cost of these for general aviation use in the Figure 1.5.4 shows a comparison between materials drop to reasonable levels.

the specific tensile stress vs specific modulus characteristics of composite materials and metals.

Design techniques with composite materials presently utilize sandwich construc- as fiberglass or tion to a great extent. A lightweight core material, such paper honeycomb, or foamed plastic, is used between laminae of pre-impregnated fibers. Complete structural components can be integrally bonded, dispensing altogether with the use of fasteners. Short fiber-reinforced, injection as primary ,structural components by the use of molded parts can be designed as advanced tooling methods. Eventually, large structural components, such wing and fuselage halves, can be integrally molded in one piece. Such pro- cesses should have a profound effect in reducing the manufacturing cost and weight of general aviation aircraft.

1-14

SYSTEMS CLASSIFICATION FIGURE 1.5, 5.

AVIONICS AND INSTRUMENTATION SYSTEMS AIRCRAFT MISSION RELATED RELATED NAVIGATION INSTRUMENTATION CONTROL AIR TRAFFIC • CTOL MANAGEMENT • STOL • VTOL COMMUNICATIONS ELEC rRICAL SYSTEMS 1.5.4 Avionics, Instrumentation and Flight Control principal mode of transportation The ultimate emergence of general aviation As a depends, to a major extent, on the development of guidance in the airspace.

Flying without adequate guidance is equivalent to driving on unmarked highways.

The National Airspace System, under the control of the FAA, is an assembly of equipment, installations, people and procedures set up to control mainly the movement of all aircraft operating under IFR. It has been troubled by the increasing density of air traffic, which has outstripped the availability of facilities and manpower. A new system of Intermittent Positive Control has aviation been recommended to alleviate the situation. While a major of general pilots fly under VFR conditions, extended utilization, particularly by business operators, must include increasing operation under IFR.

the division of aircraft avionics and instrumentation into

Figure 1.5.5 shows

the categories of aircraft-related and mission-related systems. The former are basic to the aircraft and independent of its use. Included in this cate- gory are the artificial horizon, directional gyro, compass, flight director and integrated displays. The last item is being developed for cathode ray tube presentation, which may someday be in the price range of general aviation users. Automatic flight control systems are aircraft-related and particularly a 3 -axis autopilot useful in VTOL and STOL operations. The requirement fcr and a computer, again, result in high-priced installations.

Mission-related systems include navigation aids, air traffic management and communication systems. The VORTAC system will continue to be used for short range navigation, but its capability will be improved by the introduction of area navigation. Other Nav-aid systems which might be used in the future by general aviation include Loran, Omega and inertial guidance.

AM will play a decreasing role domestically. VHF voice communication is expected to continue in use and eventually be augmented by a data link system. The Air Traffic Control Radar Beacon System has been adopted for identification and altitude 1"11 o r

determination, requiring the use of transponders in aircraft which operate in congested traffic areas. Another up-coming requirement is that of crash locater beacons. Highly sophisticated equipment, which is and will be beyond the price range of most operators, includes weather radar, collision avoidance systems and clear air turbulence detection systems.

equipment for general aviation use must provide the elements of All avionics safety, reliability, maintainability and economy. Redundant circuitry can be used to maintain fail-operational capability. Federal standards should govern the reliability of equipment and it should be easily removable and replaceable for maintenance. The principal barrier is economy. The high price constraint may be gradually diminished by increase in demand for advanced equipment and standardization. Typical avionics "packages" were selected for the baseline aircraft. More highly sophisticated equipment, including that required for fully automatic flight control, were evaluated in the sensitivity analyses.

It is expected that, in the next 15 years, the unit weight and cost of avionics 1970 dollars.

having a particular capability would be reduced, based on traffic becomes more is an increased capability requirement as However, there dense, and more aircraft have all-weather capability. As a consequence, it is avionics package would have approximately the expected that the typical 1955 package, but would have ;much increased same weight and cost as the 1970 capability.

1.5.5 Landing Gear Several requirements must be fulfilled in order to provide an efficient landing gear for general aviation aircraft. They embrace the ground contact elements, the energy absorption systems, ground handling control, and the minimization of aerodynamic drag. Two general types of landing gear are suitable for general aviation: the tricycle wheel gear and the air cushion landing system (ACLS).

The choice between the two depends to a major extent on the type of terrain from which the aircraft will be operated.

Figure 1.5.6 presents a plot of the ground pressure exerted by several types expressed in terms of California of vehicles against the required soil strength 1000.

GROUND PRESSURE FIGHTER & PSI BOMBER A/C CARGO A/C AUTO, LIGHTPLANE MAN AC LS FIGURE 1.5.6 AC V SOIL STRENGTH REQUIRED TO SUPPORT GROUND OVERPRESSURE .01L .001 .01 .1 SOIL STRENGTH CBR 1-12.

FIGURE 1.5.7 ACLS TYPICAL TRUNK PLENUM CUSHION PRESSURE AREA (SHADED) TRUNK PRESSURE (INSIDE AIR BAG) JET HEIrHT (CLEARANCE ABOVE GP,OUND) I z ^ ti + K T^,^^ ..

_^_-PERIPHERAL AIR JETS -_ `CUSHION PERIMETER ALONG GROUND TANGENCY Bearing Ratio (CBR). Auto and small general aviation aircraft tires exert pressures of 25 to 50 psi and are suitable for operation on relatively soft terrain. However, if mud, snow and water are to be encountered, the ACLS appears to provide the beet solution. It lies in the area of emerging tech- nology, having been subjected to considerable research and development during the last five years, including flight tests with an LA-4 airplane.

The system is designed to provide the ultimate in flotation, besides fulfilling the functions of vertical energy absorption, retraction, brackiig and ground handling. Its basic elements comprise a low pressure, high volume air supply and flexible trunk plenum with peripheral jet exits. A typioal trunk schematic is shown in Figure 1.5.7. The installed weight is generally less than that of a comparable wheel gear, but there is a power requirement as well. The latter, however, is generally about equal to that required to overcome ground friction, during takeoff, with a wheel gear. Although a pure ACLS is possible, it is recommended that an auxiliary wheel gear be added, designed for ground handling loads only. This addition will permit precise steering and mobility of the aircraft without using its own power.

Retractable tricycle wheel gear has been applied to the baseline aircraft derived in this study. In Category I t however, the ACLS has been applied to the recommended configuration as a means of increasing its utility. The ACLS would be highly suitable also, for "bush" operation, where a wide variety of terrain, including water, snow and ice, is encountered.

1.5.6 Functional Subsystems Aircraft subsystems which benefit by the emergence of new technology include environmental, fuel, flight control and auxiliary power. Environmental sub- systems include cabin pressurization and ice prevention. The advent of the turbocharger for piston engines and the use of compressor bleed air from turbo engines provide pressurized air sources, which need only be cooled to a com- fortable temperature level. For anti-icing or de-icing the aerodynamic surfaces, heating or contour changing (kith flexible, pressurized "boots") teohniques r .

can be used. The two methods can be combined by circulating hot, compressed air through a drooped leading edge formed by inflating a flexible boot.

1-13

Fuel system technology is being directed toward fire prevention and reliability.

The safety aspects are Aiscussed in Section 1.5.8. Flight control systems are moving in the direction of automation., with autopilots used in the higher-priced business aircraft. Fluidics and "fly-by-wire" systems are under development for military and commercial transports, but are not expected to be adopt^)d by general aviation in the next fifteen years. Design of the control system should stress simplicity, ease of operation and human factors in an effort to ,promote reliability and safety.

1.5.7 Utility and Convenience Features it stands to reason that the market for general aviation aircraft will increase beyond its normal growth rate if additional utility and convenience features can be provided without sacrifice of performance and without substantial in- crease in price. (' , e example is the small boat market, which underwent an amazing growth after trailering was introduced. Small aircraft, exemplified by Category T, can be equipped with easily foldable wings for nome storage and desigtxed to be towed behind a car on the road. Going one step further, automotive capability can be added to make them independent of extra vehicle support. These capabilities have been subjected to sensitivity analyses in this study, with the result that the towable version appears to be a favorable con- fit^,uration.

.Emerging technology on the air cushion landing system can be applied to impart all.--terrain operational capability to general aviation aircraft. This feature can be included without compromise to performance or cost. The recommended configuration for Category 1, shown in Figure 1.9.1, includes both of the previously described features.

Safety Considerations 1.5.8 r equir ement in aircra ft design and opera-

safety is a fundamental,, ever- present

tion. FAA regulations establish a minimum level of airworthiness to which most manufacturers adhere. Technology has and will continue to offer means of 3 increasing various aspects of safety without serious compromise of performance and cost. It is basic to safe design that one of two situations exist: a failure cannot occur; or, if a failure can occur ) there is a way out.

General aviation accident statistics show pilot error to be the I-Time cause of all accidents, amounting to about 77%. Other factors causing accidents are adverse weather and terrain, and engine, airframe, or systems failure. The individual occurrence rate of these accidents is leas than 7 percent of the tota'A'..

However, many accidents charged to pilot error are induced by deficiencies in design of the aircraft, with particular relation to human factors. Airframe and subsystems safety can be enhanced by close attention to the engine instal- lation, the fuel system and the control system, and by the design of damage tolerant structure, following the example of military and transport aircraft unavoidable, present technology offers practice. In cases where damage is many possibilities of avoiding crashes, and where crashes are inevitable, of minimizing the chances of severe injury and loss of life.

At least one Aircraft, a helicopter, has been designed to sustain impacts up to 30 ft/sec, with peak accelerations up to 15 g in the cockpit, without serious injury to the occupants. The correct technique is to provide the maximum degree of structural deformation after impact, rather than to design the struc- ture to sustain abnormally high loads. The use of an inflatable trunk, air cushion landing gear, is a step in this direction.

1-1 4 "ri

FIGURE 1.5.8 PURE & COMPOUND HELICOPTER VERTICAL LIFT CA?ABILITY VS. DISC LOADING TILT PROPROTOR TILT WING i PROP , W, ° P - LBS, / $ H P SINGLE ROTOR + TAIL ROTOR 50 60 70 0 10 20 30 W?S D - LW/SO. FT.

Safety from abnormal environmental conditions is an important aspect of the ,problem, with avoidance of storms a paramount consideration. This calls for accurate forecasting and effective data transmittal systems. While airborne weather radar sets are available, they are presently priced beyond the means of most small aircraft owners. Ice prevention and IFR equipment, however, can be made available at reasonable cost in the future.

VTOL Tectmolo& 1.5.9 VTOL airoraft, in the present and emerging state-of-the-art, fall into four rotor, tilt rotor, retractable rotor and fixed wing.

main categories; Fixed The first three fall into the low disc loading classification, while the fourth, exemplified by jet- and fan-lift systems, has inherently high disc loading.

meet the low noise to Since it is necessary to have low disc loading in order level constraint of this study, fixed wing concepts have not been considered.

standpoint, but also noise Low disc loading is desirabl y no g only from the because of ground erosion considerations. While the minimum cruise speed knots can be met with a pure helicopter constraint, in Category IV, of 150 design, it was considered expedient to look at configurations with a higher rotor can, at least, the tilt wing or the tilting speed potential. Either double the minimum required cruise speed. "Compounding" the helicopter can 200 knots or more. The technology relating to these to increase its speed A true VTOL aircraft in the following subsections.

approaches will be examined and this requirement excludes must be capable of sustained hovering flight, which is basically a STOL vehicle and was analysed as such in the the autogyro sensitivity portion of this study.

a plot of power loading versus disc loading for represen- shows Figure 1.5.8 tative VTOL configurations. The term "power loading" may be considered the obtained per unit of engine power required, hence a ratio of vertical lift tilt proprotor concept measure of vertical lifting efficiency. Although the (implying fixed wings) usually lies in a lower range of disc loading than that of the tilt wing-propeller concept, this need not necessarily be the case for general aviation consideration. The investigators of this study chose the as an alternate to the helicopter, due to more tilt wing configuration w familiarity with the concept.

1-15

CATEGORY I CANDIDATB FIGURE 1. b.1 Ca PLACE, IWO' FIELD) Low WING TRACTOR Speed constraints limit the pure helicopter to a practical maximum cruise level of 150 -175 knots; the compound helicopter to 200 knots and the tilt rotor concepts to 400 knots. In the pure helicopter,. the constraint is imposed by a combination of high .Mach number of the advancing blade and stall of the retreating blade. Compound helicopters gain by unloading part of their lift on to fixed wings, while the tilt rotor designs do this entirely.

The principal element of any VTOL concept is the rotor. The single rotor concept, with an anti-torque tail rotor, has been more widely adopted than any other and is more efficient than the tandem concept over the usual speed an range. The degree of rigidity d es:^.ed into the rotor has important effect on stability and control characteristics in the high speed range, with the "rigid" and semi-rigid types fav red over the articulated arrangement.

While the technology of the helicopter is well established, that of the tilt rotor concepts must be considered as emerging, and several problem areas are ti present. Eventually, solutions will be found with continued research and development applied to military VTOL requirements, which can have later application to general aviation.

1.6 Selection of Baseline Designs The first step in the selection of competitive baseline configurations for the parametric analysis is that of choosing the candidates. The choice for each category was not made arbitrarily. 1 number of practical configurations for each category were selected for intuitive consideration. A point system was as cost, created, assigning weighted maximum point values to such criteria safety, flying qualitites, performance, comfort, reliability and growth poten- tial. Members of the study team and technical e4visory personnel were asked to assign points for each criterion to all of the configurations nominated in each category. This resulted in the selection of two per category for the parametric analysis.

include a single engine, F'3ure 1.b.1, The Category I candidates, shown in low-wing, tractor propeller design and a single engine, mid-wing, tail boom pusher propeller configuration. The former has the advantages of shorter length, .

weight and lower drag, while the latter combines better visibility, lighter lower cabin noise level and easier cabin access. However, other considerations are involved, and only the results of parametric analysis can lead to 'a selection.

CATEGORIC 11 CANDIDATES FIGURE 1.6.2 (4-PLACE, 500' MELD) SINGLE K OPELLER LOW WING SINGLE ENGINE CROSS-SHAFTLD PROPS DUAL PROPELLER HIGH ."WING are The Category II candidates are illustrated in Figure 1.6.2 1 both of which a ow wing and a single tractor single engine designs. one is configured withl propeller and the other with a high wine and two outboard tractor propellers singe pusher a driven by a cross shaft. However, in the final analysis, propeller design was chosen. The advanuge of the tractor propeller in pro- viding lift augmentation by slipstream deflection cannot be used to establish minimum flight speed, since engine failure during takeoff and landing operations would create an abrupt stall.

Category YTS, both candidates shown in Figure 1.6.3 are twin engine aircraft.

In a conventional high wing configuration with tractor propellers, while One is the other is a tractor-pusher arrangement with both engines on the center line.

The extremely large propeller diameters required to meet the specified noise the high wing, tractor configuration from the standpoint of cabin level favor access and appearance. However, the propellers have to be located so far out- board that an interconnecting cross shaft is required for control with one engine inoperative.

In an effort to assess the effect of providing a higher cruise speed, a configuration using a single turbofan engine was added to Category III for the sensitivity analysis. The reasons against using twin turbofans are excessive cost and the established better reliability of the turbofan over the shaft engine propeller combination.

1-17

CATEGORY III PROPELLER CANDIDATES

URE 1.6. 3

FIG (6 PLACES, 1500' FIELD) HIGH WING, TWIN ENG.

TRACTOR

With a minimum cruise speed requirement of only 150 knots, the helicopter is

a prime candidate in Category IV. Since higher speed is a desirable charac-

teristic, a tilt-wing-propeller configuration was selected as a competitor.

Both are shown in Figure 1.6.4. The relatively high sower requirements,

especially for the tilt wing, led to the use of a turboshaft engine. The

helicopter design is conventional and constrained as to disc loading and

rotor solidity ratio by the requirement for low noise level. The tilt wing is

similarly constrained, and its tilting motion is interconnected with flap

travel to develop maximum lift and avoid stall during the transition.

CATEGORY IV CANDIDATES

FIGURE 1.6.4

(a- PLACE, VTOL) TURBOSHAFT ENG, /1111\ ^' HELICOPTER TURBOSHAFT ENG.

CROSS o ^L`.^ SHAFT PITCH CONTROL FAN-_ a TILT WING - DEFL. PROPELLER THRUST RAMMED Pl_ i TAIL 1-1$

kA M ;a,dy. kYY^ .A tip.

FIGURE 1.7.1

.y ^•••••••.• •^ idYA LwI N A !dA,,kt` wM' Fi ""^1...^...^. ^ ^...^ ^.^..

^ _wal%Y.^ Id+ ► Mk'.i rfA;;A iSsMi`:r 1 ^.. ^ rQk,A?! Mu YtL^ ^4 } + r m4k ,1r,LYAuTLAIn aN'^1t?,YK^^A?+YYIA'd Ak.IJ^ ka.rrlflC;A.'a_s it a cu'y vat r' _T l b # t t .k rAY F Alt !'Aia , .,.._ ..«..... _ , i _ _ 1'; Al, •kj; ^'- i Y'hL_ j s.u_ g ti Ytt^ • ^+», x,r5 +NaA Il'+'XAL1AY9b' A', *.

a y ^^: i ''Q ^4tA Y, f^^S^'+ ,4t , y N` ,A'i^Y:1d AYJ w k t ^,,,.t;;; I ,:A,Is A.A ,li , I xY.,., Yr..0 A'i^ Y^rAt':: T1;A,.L:;r^ r I r rr^ ^I :1^ . 7 k'YO,,,,''`J.ruIU.. rr,`Yy A.,k`c x ktA'u'3e;, :y e^...4u' 'Au'e 3t A.Sl^ , _ t ^Y'tYYA 4'^ C^ ,^; ^"iu,71^'^ x^nY'A

1.7 Parametric Analysis

1.7.1 Methodology

The parametric analysis procedure used in this study is applicable to

optimization of the present technology baseline designs, covered in

this section, and to the sensitivity analyses, covered in Section 1.8.

The computerized analysis has the capability of estimating performance, costs, and weights.

Fiore 1.7.1 shows a flow diagram of the procedure. Initial inputs to

the analysis comprise an assumed gross weight, wing aspect ratio, cruise

speed and altitude, cruise drag coefficient and cruise propeller efficiency.

Cruise power is then determined, after which the range, specific fuel con-

sumption and the weight subroutine are entered using an assumed gross weight.

A complete weight analysis is then made from the weights subroutine on the

basis of vehicle geometry, payload and fuel requirements, and gross weight

is calculated. The calculated gross weight is checked against the assumed

gross weight and an iteration process is performed until the difference is

within a specified tolerance. The static propeller thrust-to-horsepower

ratio (for the required noise level) and the ratio of takeoff power-to-

cruise power are input to calculate takeoff distance. The output is com-

pared to the required figure and additional iterations of gross weight and

power are performed until stabilized outputs are determined. The readouts

include: gross weight; weight empty and its subdivisions; fuel capacity; d-.

L/D; wing area; wing loading; rated T.O. power; takeoff distance; initial

cost and operating cost.

1-19

PRICE TREND OF FIGURE 1.7.2 10,000,000 GENERAL AVIATION AIRCRAFT WITH WEIGHT-SPEED PRODUCT 42 & ENGINE 1,000,040 TURBOJET & TURBOFAN BASIC PRICE.

2 ENGINE (1970$) TURBOPROP 100,000/ING AR2 ENGINE RECIPROCATING 1 ENGINE a LANDING GEAR 10,000 °I 5 106 10 107 WT. EMPTY X CRUISE SPEED (LBS. MI./HR) Inputs to the program are based on present technology for the establishment of baseline configurations and advanced technology for the sensitivity analyses. These include propulsion and structural material, with others as appropriate to the desired assessment.

Statistical formulas were derived for the determination of structural, sub- system and equipment weights, while that of the engine is based on rate power and technology leve- l . The latter factor is also applied to the structural weight groups.

The collection and correlation of cost data was a major undertaking of this study. Costs were subdivided into initial and operating coat. Statistical data were compiled from literature, contributions from general aviation air- craft manufacturers, and from NASA. Engine and propeller cost data were obtained from the leading manufacturers. Coat trend curves for complete air- craft (excluding avionics) were developed as a function of the Weight Empty X Cruise Speed product, as shown in Figure 1.Z.2. A breakdown process from the list price was developed so that the e ffects of each component part - airframe material and labor; engine, propeller and equipment; overhead, profit and dealer's commission - can be separately assessed. The cost per pound of heli- was copter airframe found to be considerably higher than airplane hardware.

Projections were made into the 1985 time period, assuming that fiber composite materials will be used. This included estimates of material cost per pound and a study of applicable manufacturing methods for minimum man-hours per pound.

Learning curve slopes were developed for the assessment of high production quantities - up to 100,000 units per year. Case histories were studied in an effort to check development costs, which are usually amortized in production costs. A figure of $1000 per pound of gross weight appears to represent an average for general aviation aircraft. The initial cost model was used to was found to be accurate within 10%.

check the cost of actual aircraft and 1-20

FIGURE 1.7.3 OPERATING COST FACTORS SUMMARY CATEGORY ELEMENT 1 II III IV VARIABLE COST (HOURLY) FUEL & OIL AVG. FLOW, COST/GAL.

INSPECTION & MAINT. EMPTY WEIGHT, TOTAL POWER RESERVE FOR OVERHAUL TOTAL ENGINE POWER $.90 PARKING, LANDING, $.55 $1.70 $1.70 SPARES FIXED COST (ANNUAL) DEPRECIATION 20 YEAR LINEAR INSURANCE HULL 4% 3% 2% 12% LIABILITY $200 $300 $450 $800 FAA USE TAX $25 4 GW CHARGE STORAGE $300 $600 $900 $600 PILOT - - $15,000 $15,000 MISCELLANEOUS $100 $150 $200 $200 various sources information, An operating cost model was developed using of with particular reference to a DOT report (Reference 1.6). Operating cost factors are listed in showing differences assumed in each of the Figure 1.7.3 to be flown by four categories. Categories III and IV aircraft were assumed professional pilots. Program readouts included cost per hour, cost pei mile

and cost per seat-mile for yearly utilization figures of 100 9 300 and 500

hours. The effect of utilization on aircraft-mile cost for all Categor- ies are the need of high shown in Figure 1.7.4, which tends to emphasize utilization for economic operation.

1.80 FIGURE 1.7.4

1.60 AIRCRAFT - MILE COST TREND WITH UTILIZATION 1.40 1.20 OPERATING 1.00 COST $/MILE .80 3ORY .60 IV III .40 1..

.20 I i 100 200 300 40'0 500 UTILIZATION (HRS/YR) 1-21 .tiny

CATEGORY I PARAMETRIC FIGURE 1.7.5 ANALYSIS RESULTS CONFIGURATION TRACTOR PUSHER GROSS WT. (LBS.)

2,847 2,810 TYPE OF ENGINE RECIP RECIP T.O. BHP CRUISE SPEED (KTS) CRUISE POWER (PCT. NORM.)

PROP. THRUST (LBS/HP) 6.0 6.0 PROP. DIAM. (FT) 7.91 7.91 WING LOADING (LBS./SQ.FT.)

11.84 12.16 INITIAL COST ($) 30,373 29,669 OPERATING COST ($/MILE) 300 HRS/YEAR 0.158 0.156 i ;I 1.7.2 Results and Baseline Configuration analysis was the establishment of baseline The first step in the parametric designs in each of the four categories. The program analyzed the competitive configurations in each category. The airplane selected from leach configura- tion study was selected on the basis of the lowest gross weight and direct operating cost. These were then compared and one was selected as a basic configuration for the sensitivity studies.

are equipped with present technology reciprocating engines, Category I aircraft of normal rated power. A comparison which propel them in cruise flight at 75% Figure 1_7.5, reveals of the tractor and pusher propeller candidates, shown in very close in weight, power and cost. a cruising speed of that they are chosen as the highest obtainable knots, with retractable landing gear, was without an appreciable increase in operating cost. A check was made in this category to assess the effect of using conventional propellers with a much noise level propeller produces higher noise level. Surprisingly, use of a low an airplane which is lighter and less costly to buy and operate. This conclu- sion was found applicable to Category I only.

shows the mid-wings pusher propeller configuration selected as

Figure 1.7.6

the baseline design for_Category I. Since it was only marginally better than tractor, it was selected more for qualitative reasons. These include: superior vision, low interior noise level, easy access to the cabin and safety from whirling propeller contact on the ground.

1-22

I

tl7k)

i-^

FIGURE 1.7.6

IG

GROC,t, WEIGHT 2610 LBS.

GENERAL W[Nr, AREA SQ FT

ARRANGEMENT -'31

MAx EN(, H P 174 PROP DiAM, 191 FT,

CAT. I BASELINE

AIRCRAFT

WING ASPECT RATiO 8-00 2, 40 W_ " _ WING TAPER dATiO 0-50 WING SWEEP 0.250 0• ifi I ^0 I vF - ---- - T -- --- 31 4' - - ---I

-- 410'

1-23

.7.7 CATEGORY II PARAMETRIC

FIGURE 1

ANALYSIS RESULTS TWIN PROP.

SINGLE PROP.

CONFIGURATION 6,450 4,600 GROSS WT. (LBS) TURBCPROP TURBOPROP TYPE OF ENGINE 545 600 T.O. BHP 200 200 CRUISE SPEED (KTS) 80 90 CRUISE POWER (PCT. NORM.)

6.0 5.0 THRUST (LBS/HP) PROP.

11.8 12.0 PROP. DIAM. (FT.)

11.4 12.0 WING LOADING (LBS/5Q. FT.)

215,000 131,500 INITIAL COST ($) 0.475 0.335 OPERATING COST ($/MILE) 300 HRS/YEAR Category II aircraft are equipped with turboprop engines, which were found superior to the reciprocating type on all counts. In this instance, cruise power is 90;% of normal. rated. Figure 1.7.7 shows a comparison between the single and twin propeller versions, which points to the former as the better approach.

Having selected a single propeller configuration, it was decided to retain the pusher installation, as in Category I, for the same reasons. While the tractor propeller has the apparent advantage of slipstream deflection by the wing to augment lift, failure of the engine at a critical momen t during takeoff or landing would lead to an abrupt stall. This dictates that minimum speed be based on power-off lift, negating the lift augmentation advantage of the tractor propeller.

Figure 1.7.8 shows the general arrangement of the Category II baseline airplane.

Since it is similar to the Category I airplane in design approach, it reflects the penalties paid for reducing the field length from 1000 ft. to 500 ft. These 66% larger wing and over 200% more engine power.

higher weight, a include a

6 4%

Initial cost is increased by a factor of about 5.

1-2^+

a

FIGURE 1.7.8

SS NO AREA 304 Su FT W MAX ENO H P 545

GENERAL ARRANGEMENT

PROP OIAM- 120 vT- 1VrN6ASPEf.i pAYrO 57e' TAPER RAT.0

CAT. II BASELINE AIRCRAFT =0 056

IO SWEEP 025c 0'

_ 555' r

1-25

.7.9 CATEGORY III PARAMETRIC

FIGURE 1

ANALYSIS RESULTS TRACTOR-PUSHER TWIN TRACTOR CONFIGURATION 11,283 9,778 GROSS WT. (LBS.)

TURBOPROP TURBOPROP TYPE OF ENGINE T.O. BHP 532 250 250 CRUISE SPEED (KTS) 90 90 CRUISE POWER (PCT. NORM.), 6.0 5.0 PROP. THRUST (LBS/HP) 18.2 17.7 PROP. DIAM. (FT.)

29.4 WING LOADING (LBS/5Q. FT.) 40.9 426,181 356,040 INITIAL COST (;) HAS/YEAR 0.8r 0.74 OPERATING COST ($/MILE) 300 Category III aircraft are also powered by turbine engines, as a result of a comparison study with piston engines. The conventional twin engine approach with tractor propellers, was evaluated against the centerline twin engine installation having tractor and pusher propellers. The comparison is tabulated in Figure 1.7.9 where the advantages of the conventional arrangement are apparent. It has the same symmetrical thrust characteristics of the centerline engine model, since the propellera, because of their large size and consequent outboard location, must be crass-shafted. The general arrangement of the _ selected design is shown in Figure 1.7.10 which graphically portrays the large j propeller diameter required to meet the low noise level constraint.

I^ I T FT

TILT-WING- PROPELLER HELI COPTER CONFIGURATION

FIGURE 1.7.11

150 CRUISE SPEED (KTS) TUROOSHAFT TYPE OF POWER PLANT TUROOSHAFT CATEGORY IV PARAMETRIC 6918 5646 GROSS WEIGHT (LBS) ANALYSIS RESULTS (2) 19.9 (1) 47.2 PROPELLER OR ROTOR DIAMETER (FT) 1282 641 MAX. RATED HORSEPOWER 133 - WING AREA (SO. FT.)

. 25.0 - WING SPAN (FT.)

11.24 3.40 DISC LOADING (PROP. OR ROTOR) (LSS/TT.2) 4756 3.02 WEIGHT EMPTY (LOS.)

1262 1265 FUEL WEIGHT (LOS) 376,000 270,406 INITIAL COST ($) 1.03 1.39 HRS/YR OPERATING COST ($/MILE) 300 placed the tilt wing — propeller concept The Category IV aircraft comparison reflecting contem- against the helicopter. Again, turbine engines are used, porary VTOL aircraft practice. Figure 1.7.11 shows how the two approaohes compares reflecting the differences in disc loading. The tilt wing has twice much power. This effect escalates the cruise speed, but also requires twice as its price to 409 more than that of the helicopter, although its operating cost is about 25% lower. Since VTOL airc .ft are operated, mainly, over shorter compared with fixed wing aircraft, the speed advantage of the tilt distances as wing is not considered to be worth its higher price. The helicopter was there- fore selected, and its general arrangement is shown in Figure 1.7.12. Its y ratio, reflects the comparatively large rotor diameter, with a high solidit low noise level and high cruising speed requirements.

FIGURE 1.8.1 SENSITIVITY ANALYSIS PROCEDURE PRESENT TECHNOLOGY BASELINE DES IGNS ADVANCED ENGINES LA ^A CED AAATERIALS ADVANCED TECHNOLOGY BASEI'- IE DESIGNS I, EXTERNAL NOISE LEVEL VAR. FIELD LENGTH T. It PRESSURIZATION AND VAR. CRUISE SPEED i TURBOFAN (CAT. III) HIGH CRUISE ALTITUDE VAR. CRUISE RANGE ADV. AVIONICS & AUTO.

SEATING G ROWTH FLIGHT CONTROL WING FOLD OADABILITY PROD. QUANTITY GROWTH EXTRA SAFETY PRO:'.

o STRUCTURAL LALL-TERRAIN CAPABILITY o SYSTEMS Sensitivity Analyses 1.8 1.8.1 General Procedure Having established the present technology baseline designs and having examined the emerging technology, the next step consists of the series of sensitivity analyses outlined in the chart. The analyses follow the same computerised procedure used in the parametric analyses.

The purpose of this analysis is to assess the impact of advanced technology

and other factors on the baseline designs reported in Section 1.7. Figure 1.8.1

illustrates the general procedure, which begins by assessing the impacts of advanced engine and advanced mater Al technologies, separately and in combina- +ion. 'the latter establishes new baseline configurations, with which the remaining factors are assessed. Inputs and outputs of the computerized analysis are of the same type as described in Section 1.7.1.

1.8.2 Advanced Technology Baseline Designs

The advanced technology baseline designs were established by assess i ng the effect of advanced propulsion systems and the use of advanced structural materials.

These effects were ant - yzed separately and in combination.

From the examination of applicable propulsion systems in Section 1.5.2, four reciprocating, turboshaft, turbofan and types of engines were selected: rotating combustion (RC). The first three represent present state-of-the-art, while the fourth must be classified as emerging. The baseline designs are The sensitivity powered by either reciprocating or shaft turbine engines.

analyses assess the RC engine installation as a power plant for each category of aircraft. The results expressed as percentage improvemr-, y s over the base- line aircraft characteristics are listed in Figure 1.8.2.

FIGURE 1.8.2 EFFECT OF ADVANCED PROPULSION (ROTATING COMBUSTION ENGINES) CATEGORY I II III IV BASELINE ENGINE RECIP, TURBOPROP TURBOPROP TURBOSHAFT PCT. IMPROVEMENT GROSS WEIGHT 4.5 6.1 4.9 2J.3 3.0 MAX. H. P. 0.8 20.8 15.9 50.1 INITIAL COST 15.8 28.8 35.3 * 300 HRS/YR UTILIZATION 17.5 OPERATING COST * 6.5 3.6 20.2

NOURE 1.8.3 EFFECT OF ADVANCED MATERIALS (FRIER COMPOSITES) III IV CATEGORY PCT. IMPROVEMENT 8.5 17.5 17.0 11.4 GROSS WEIGHT 13.9 12.5 1.4 8.3 MAX. H. P.

13.2 13.1 18.5 17.0 INITIAL COST 6.5 10.6 15.5 11.9 OKKATING COST* For the assessment of the e,;fect of using advanced structures, weight reduc- tion factors and cost factors were derived to reflect the use of advanced com- posite materials. In comparison to conventional aluminum structure, the par- chased materials are costlier and the manufacturing costs slightly higher.

These handicaps are overcome by reduced weight and its effect on size and power The results, expressed as percentage improvements, are listed in required.

Figure^1.88.3.

The effects of advanced propulsion and airframe structure are combined to establish advanced technology baseline aircraft, with which to assess the impact of other factors. The results. expressed as percentage improvements Figure 1.8.4.

over the present technology baseline aircraft, are listed in These improvements are substantial and emphasize the importance of applying advanced technology to future general aviation aircraft. The advanced tech- xq ; nology configurations for Categories I t 1I 0 III and IV are shown in Figure 1.8.5, 1.8.6, 1.8.7 and 1.8.8 respectively.

,- y4 FIGURE 1.8.4 COMBINED EFFECT OF ADVANCED PROPULSION AND MATERIALS (ADV. TECHNOLOGY BASELINE AIRCRAFT) CATEGORY II III IV PCT. IMPROVEMENT GROSS WEIGHT 14.5 22.0 18.2 32.7 MAX. H. P.

10.0 12.4 2.2 25.5 INITIAL COST 29.5 63.2 48.8 43.4 OPERATING COST 17.0 31.0 15.8 27.4 * 300 hours per year utilization 1-29

t I' Y

FIGURE t .8.5

GENERAL ARRANGEMENT

CAT. I ADV. Tr.:H. AIRCRAFT

GRC'.,c 4EIGHT 228SL8S.

W" v AREA 159 SG PT MAA %kG. N.P. 152 PROR DIAM.

7.37 RT.

WING ASPECT RATIO 8.00 WING TAPER RATIO 0.50 WING SWEEP 0.25C.

s?v^` 9.0' 1 i ': s i PROP DiAM. FT.

11.16 WING ASPECT RATIO 8.00 WING TAPER RATIO \\ N 05C WING SWEEP 0250 0•

*ft, AREA gmu"i rT MAX 05 HP P ROP D'AM F r r5j W , NG ASPECT RAT NO 6 ou WKNG T APEP RAT 10 050 W,NG SWEEP 0.25C 0• } r , N i' I

FIGURE 1.8.8

GENERAL ARRANGEMENT

CAT. IV ADV. TECH. AIRCRAFT

G -14069- WEIGHT L®S.

MAIN ROTOR DIAM, 37.75 Ft DISC LOADING 3A LKAQ FT.

ROTOR SOLIDITY 0.10 X ENGINE H.P 477

FIGURE 1.8.

9.

CATEGORY I COMPARISON: FOLDABLE WINGS & ROADABILITY (ADVANCED TECHNOLOGY VERSIONS) BASELINE TOWABLE AUTOMOTIVE GROSS WEIGHT (LBS) 2350 2670 MAX. ENGINE H. P.

156 178 CRUISE SPEED (KTS) 145 140 INITIAL COST ($) 15,600 14,400 18,250 OPERATING COST (300 HRS/YR) (S/MILE) 0.11 0.12 0.14 1.8.3 Alternate Configurations Alternate configurations investigated in this study include the following: the roadable airplane in Category I; the autogyro in Category II; and the effect of turbofan propulsion in Category III.

The roadable configurations in Category I include foldable wings to facilitate home storage and to permit towability on the road. Automotive'oapability, using an auxiliary power unit to drive the wheels, was also assessed. A com- parison of both versions with the advanced technology baseline aircraft is tabulated in Figure 108.9. A high wing tractor propeller configuration, With fixed landing gear and wings which fold backward in the horizontal plane was evaluated.

The autogyro was not considered as a baseline candidate in Category II.

Although it can approach the vertical performance of the helicopter, it is not a, tr - 7 ML aircraft and hence must be considered in the STOL category. It is, howevv eA., capable of a "jump" takeoff and a flared landing without substantial ground roll. In this analysis, it was tailored to the 500 ft. field length by using that distance for climbout over the obstacle, following a jump takeoff.

Advanced propulsion and materials technology were applied. A comparison with its fixed wing counterpart is tabulated in Figure 1.8_10. The calculated

price is 4.6 9 which reflects the higher cost per pound

higher by a factor of of rotary wing hardware. This includes components of the rotor system and the transmission, as well as the authorization of costly researh and development programs over a comparatively small number of production aircraft.

FIGURE 1.8.10 CATEGORY 11 COMPARISON: FIXED WING VS. AUTOGYRO (ADVANCED TECHNOLOGY VERSIONS) FIXED WING AUTOGYRO 4,000 3,336 (LBS) GROSS WEIGHT MAX. ENGINE H.P.

a 45,000 207,000 W INITIAL COST 0.84 0.93 OPERATING COST (300 HRS/YR) (S/MILE) 1-32

The 6-place aircraft of Category III is designed for long cruise range (1500 miles) and high cruising speed (250 knots). The application of turbofan pro- pulsion was analyzed to assess the cost of attaining even higher speed. In order to minimize the initial cost, a single turbofan engine was uses, since the cost per pound of thrust decreases considerably with the increase of rated thrust. Also, the reliability of the turbofan engine has already been estab- listed at a much higher level than that of a displacement engine/propeller combination. The general arrangement of this airplane is shown in Figure 1.8.11 and its cc^parison with a twin engine/propeller aircraft is tabulated in Figure 1.8.12, with both airplanes cruising at 20,000 ft. The optimum cruise speed of the turbofan aircraft is 300 kts and might be faster at a higher altitude. Its price is 65% higher, although its operating cost is only 4% higher. Despite the cost handicap, the turbofan approach should appeal to a large segment of potential corporate aircraft users.

1.8.4 Avionics and Subsystems This division of the sensitivity analyses includes avicnic systems, extra safety features and pressurization (in combination with high altitude opera- tion).

The baseline aircraft (both present and advanced technology versions) do not include avionics equipment. This is in keeping with the present policy of general aviation aircraft manufacturers, whose basic prices are exclusive of avionics. For the assessment of advanced avionics, equipment lists were com- piled for each category of airplane.

^a The equipment for Category I is selected for VFR operation in controlled air- space. It includes VHF communication, VOR/DME navigation with an Area Naviga- tion computer, and an ATC transponder. The equipment is estimated to weigh 40 lbs. and cost ;6,000 installed.

The equipment selected for Category II, and which is also assessed for Categories III and IV, permits minimum capability IFR operation. It includes VHF communication; VOR/ILS/DME navigation with an Area Navigator computer; ADI/HSI displays; an autopilot/flight director; and an ATC transponder. The equipment is non-redundant, is estimated to weigh 70 lbs., and cost $179500 instal,oq.

categories III and IV are also assessed for the installation of equipment which permits maximum capability IFR operation equivalent to that of the air- lines. It provides dual redundancy in the oommunication and navigation equip- ment of Category II; electronic attitude and horizontal situation displays; an autopilot;/flight director; an ATC transponder; weather radar and a collision avoidance System,, This equipment is estimated to weight 150 lbs. and cost $48,000. It is designated "A" and the Category II equipment is designated "B" for assessment in Categories III and IV.

1-33

G ROSS WEIGHT $776 LOS 296 SO f T W I NG AREA MAX ENG-THRUST 2875 LOS WING ASPECT RATIO B00 WING TAPER RATIO 0 50 WING SWEE P 0250 0' OAGGAGE SPACE 24 CU ITT r 360, 11.6" -,r4ot-( FIGURE 1.8.12 CATEGORY III COMPARISON: PROPELLERS VS. TURBOFAN (ADVANCED TECHNOLOGY VERSIONS; 20,000 FT. CRUISE ALT.; 85 PNdb AT 500 FT.)

2 ENGINE/PROP. SINGLE TURBOFAN GROSS WEIGHT (LBS) 6,624 8,776 MAX. H.P. OR THRUST (LBS) 756 (HP) 2,875 (LBS) CRUISE SPEED (KTS) 250 300 136,200 207,300 INITIAL COST (5) 0.51 OPERATING COST (300 HRS/YR) (S/MILE) 0.53 Noise Level 0500 ft.

(PNdb) 75 85

1 -34

FIGURE 1.8.14 EFFECT OF ADVANCED AVIONICS AND AU'T'OMATIC FLIGHT CONTROL CATEGORY 1 11 III IV ALTERNATES A B A B PCT. INCREASE IN: GROSS WEIGHT 3.2 3.9 3.8 1.7 9.4 4.2 MAX H.P., 2.0 1.6 2.0 0.8 6.7 2.9 INIT. COST 38.5 38.9 32.0 10.1 39.6 11.4 OPER. COST * 31.2 12.2 3.0 6.8 18.0 6.5 300 HRS/YR UTILIZATION a shows the effect of providing these equipment packages in the Figure 1.8.14 four categories of aircraft. The results are expressed as percentage increases over the listed characteristics of the advanced technology baseline aircraft.

25 to 30% over the The percentage cost increases can be compared to a range of basic price of the aircraft, which reflects the average cost of avionics in present day general aviation operation.

of safety over and a level The extra safety features assessed here provide above that required by FAA regulations. They are divided into two categories: g maneuver load structural and systems. The structural category includes a factor, a 13 ft sec rate of sink and a crash-resistant cabin structure, designed to sustain impact velocities up to 30 ft/sec and vertical accelera- g without seriously injuring the occupants. The systems category tions to 15 includes anti-icing, lateral stabilization, automatic landing flare, crash 6L beacon, remote fuel tanks and a fire-retardant system for the fuel.

both separately and in combination, assessed While the two categories have been again expressed as percentage is shown in Figure 108.151 only the total effect increases over the listed characteristics of the basic advanced technology Categories I and I19 aircraft. The results appear to be overly penalizing in but reasonable in the other two categories, especially IV. Corporate users may be willing to pay the difference. The effect on insurance rates have not rate reduction would been included for lack of specific information. A bring about, approximately, a 106 reduction in operating cost.

1 -35

FIGURE 1.8.15 EFFECT 4^F EXTRA SAFETY PROVISIONS (ADVANCED TECHNOLOGY AIRCRAFT) CATEGORY II III IV PCT. INCREASE GROSS WEIGHT 25.5 36.2 24.3 10.7 MAX. H. P.

16.5 23.9 12.8 7.8 INITIAL COST 71.0 75.0 50.5 15.9 OPER. COST * 32.2 37.1 18.7 8.7 Cabin pressurization ad high cruise altitude features are applied by pro- viding a cabin of circular cross-section in combination with the installation of turbochargers on the engines. It is assumed that this would be a minimum capability pressurization system consisting of a turbocharger with an inter- cooler and appropriate controls, a pressurized fuselage and a regulator. Low altitude refrigeration is not provided. Application to Category IV is not the low rotor speed of the helicopter would lead Zo retreating assessed, becausie tabulates the effect on the blade stall in low density air. Figure 108.16 basic advanced technology aircraft characteristics, expressedits terms of per- cent increase or decrease. It is wholly beneficial for Category II and III aircraft and marginally so in Category I. The reduced wing loading required for optimization, however, requires a 47% increase in wing area, which compli- cates ground har,41ing and storage, and increases gust sensitivity. The results reflect the dominating influence of reduced engine power and fuel consumption in opposition the added weight and cost of structure and equipment.

to FIGURE 1.8.16 EFFECT OF PRESSURIZATION ANC HIGH ALTITUDE CRUISE (ADVANCED TECHNOLOGY AIRCRA (- r I I I I I I CATEGORY PCT. INCREASE GROSS WEIGHT 2.4 -1.9 -14.6 MAX. H. P. -12.5 -18.8 -24.4 INITIAL COST 2.6 -7.1 -20.9 OPER. COST * -5.4 -13.1 -15.0 * 300 Hrs/Yr Utilization

1=36

FIGURE 1.8.18

' FIGURE 1.8.17

EFFECT QF

FIELD LENGTH QN PRICE EFFECT OF N015E LEVEL ON PRICE

r'+w^YE ISY6.Yin-iu .'^'.i,E M$IlHJUI , - CAT. III - CAT. I" CAT. IV IIV R- 1r f J a{ {^ J ♦ . ♦ , ^ ♦ a^ u A R ♦ Too 4-PEACE AIRCRAFT R r ♦ cY? w ♦♦ a y ♦ lJ i .• il d ♦ ..

—R ^ ^A II^ ^;Y ,II 4pyy f? ^ "y;. ♦ *NIR ^.Y y `y ^ ,♦ li$$F..i f R eII «??_ CAT .III ^. ♦ ,' red 1 t?r {^I1 ?:^ r R.-R._ * RR X + - p- ♦. -JY AA r.

y] A A. AJlR f- ♦. ^.^ R 1.

.^A^1 3 {^1R ^, A-: ^hRIIII Ik ?_ y¢ y ,. y9..

AA «?

1J ?? ?Np CAT .1 .

,.

.1W IVVV IJVU LVVU wWu °o

FIELD LENGTH (FT.)

AT .5W FT_ 11'Na) XTERNAL NC06E LE'vEL

1.8.5 Performance Variables

These assessments include variations of external noise level, field length, cruise speed, cruise range, and payload capacity.

The standard noise constraint of this study is 75 PNdB at 500 ft. and is

believed to represent a practical level. To assess the penalties, if any, due

to quiet operation, propellers were selected for performance without regard to

noise, and an intermediate level of 85 PNdB was assessed. Figure 1.8.17 shows

the effect of external noise level on price. It is relatively insensitive to

the aircraft of Categories I and IV, mildly sensitive in Category II and very

sensitive in Category III. This effect is in line with operational considera-

tions. Aircraft in Categories I, II and IV would operate in an out of close-

in airfield:, while those in Category III would use major and satellite air-

ports, where a higher noise level would be tolerated.

The required field lengths are 0, 500, 1000 and 1500 ft. for Categories IV, II,

I and III respectively. Figure1.8.1_8 showe the effect of field length on

price, with variations within Categories I, II and III. The Category I air-

craft is insensitive, but those of Categories II and III are substantially

affected. The "intercategory" dashed curve connecting the minimum field

length points of Categories I, II and IV, illustrates the effect of field

length on the price of 4-place aircraft, showing a sharp rise below 1000 ft.

This curve is not truly representative, since the aircraft of Categories I,

iI and IV are designed for different cruise speeds. For instance, at the

same field lengths, the higher cost of Category II aircraft over those of

Category I reflects higher cruise speed performance.

1-37

FIGURE 1.8.20

FIGURE 1.8.19

CEtk^T r^r ^k^_M',^i .

',PkGU ^s^^ ^sPE1F^T11Y^ w'^T

EFFECT ^ -T QRUISE SPEED VN PRICE ^41^^E rSpEr^ri+;d CAT h,

CAT. III I

CAT. IV a .

I _I

Rey

- .4Y aA ,1 ♦,.

- a..a 1 4 a.. a s i Y-< :...- F a ,^ a Y.}.} Y a 0. i a- YIIi e1 ^.

',IIa ..

xO^ Y a ii R

: CAT, III

II ♦♦ ,i-• ti- .a+ a^ } : *" '.III ^:^^ CAT S N ^^' .

L4 1 ^ e a! II «IIs } aY ♦ R}y R} II.

1 sa.l . 1.• ^ is «,fa }}Y^ A' aFr. '} v ".. 4 -^—ApRl,a `i4 .x, .YYeAR B (r d ^.a } f „1t 4 Y Y}}} ♦ y -R II« ,1 - 1 yr 1l A{ ♦ Y(1 : } a.Y $ R # AIIY'Y^yp :II, Y i.A•. # ♦♦ T , }}PY ^YA R t.

..1:l:YM A , M1 Y } } Y ♦ f 1 a / • 11 • 1 M 1-* }— ♦♦♦ # a i.Y J * k Y a .

} A S :1 il^p Y .

4 : A-iti ^^a^ tl.

T «}^}: i

l Y

^ e

!4 ^ •;-.

II

e i "! » Y 500 FT T.O. * } } 1000 FT. T.O " x h

Y.

R . a :. . : . Y ^ i^Y^

C

J A } R 4 ^ Y I -*. T« 11 Ya

i^

if If

`i^

1 ^ ^ A Y.y 500 T

Y FT$y. t S7 `

Y

1000 FT

$ T.O

:+

a II«+ 1 p_ 1 A_ Y }{A Y11 ^ Y Y { Y b4 Y *Y }+-

RA -1 t {+tT,r

- Y

yY^l Y Y T } .

CAT I

41r }, II CAT I } "..

s

}, YY y ? ^^ ll i . Y G 2 ; IIII: ' ♦ III:}^ i- YY i la .1^ iaYII.tA .Y ♦ ',YX4

L ,. -^R `H

100 200 300 0 0

CRUISE SPEED (KNOTS)

CRUISE SPEED (KNOTS)

The price of aircraft in all categories are very sensitive to design cruise

speed, as shown in Figure 1.8.19. Category I, however, is relatively insen-

sitive between 130 and 160 knots. The curves of Categories III and IV are

nearly asymptotic at the study requirement values. Figure 1.8.20 shows the

effect of cruise speed on operating cost, showing similar trends and maximum

sensitivity in Category IV.

Figure 1.8,21 shows the effect of cruise range on price. Sensitivity varies

with the numerical order of the categories in much the same manner as cruise

speed. None, however, appear to be range-limited within the limits investigated

PRICE ($1000)

i ;1;1 ^ ^^^ II rtA

1 ji l t

, " Iii ;;" tl: II ^Qut' i M ) }T

FIGURE 1.8.2 11

d^ y _

-

O ^t

h i

IIII: CAT. Ill

iAI

II1

EFFECT OF CRUISE RANGE ON PRICE i

T Y

r I Y A+ 44I Y Y.

Y ^P+ (^+

Y i Y IV

t R

_

}.'^ }

,i^xCAT. , t-

t

)

"I to

,..)

1 T1iII ^y ) ^ paII^ a . .

a l II } ltY ,t II: I:Y x R A" YIIR1I:^^.

y $1 ^.^ ei^ Y I Y ^ } II 11// Ar *+.^ ;^IIi 1.

M.Q ♦ t ! y^}^^- } H } +fi Aylp 1 py ij Y j i 1 y Il ll]]y

j

CAT I I

x { 9` sYp dIx y.

tt n « YY ^^

^ ^yI{}I )

u^^ ^ ^ 1 ^

^ ° CAT I 0 300 1000 1500 2000 2500 {

^CRUiSE RANGE (STAT. MI. WITH

ttilN. RMRVE)

FIGURE 1 PRICE

.8.22 - EFFECT OF SEATING CAPACItY ON PRICE AND SEAT- SEAS`-MILE ($1000) MILE COST COST 5CX 22.5 20.0 19^ 10.0 7.5 5.0 2.5 4 6 8 10 4 6 8 NO. OF NO. OF SEATS SEATS 50 increase Each advanced technology, basic aircraft design was assessed for a in seating capacity. This was accomplished by lengthening the fuselage of aircraft, in Categories I, II and III and widening it for 3-abreast seating in Category IV. In Figure 1.8.22, the effect on price is shown by the solid lines, and on seat-mile operating cost by the dashed lines. The latter effect is meaningful to business aircraft owners and shows that Category I aircraft offer the lowest personal transportation rates, followed by II, III and IV aircraft in that order. If the straight lines were extrapolated, they would show that 14 seats in aircraft of Categories II and III, and 11 seats U in aircraft of Category IV, would be required to meet the seat-mile cost of Category I 4-place aircraft. The differences reflect increased performance and complexity.; 1-39

FIGURE 1.8.23

-EFFECT OF 'YEARLY PRODUCTION RATE ON PRICE PRICE ($10®tl<j CATEGORY ttt ,^ 7t 40.

-------- lU 1 2 0.2 0,4 4 6 10 20 40 60 0,6 YEARLY PRODUCTION RATE (THOUSANDS) 'uc ^ wt-- I

1.8.6 Increased Production

Figure 1.8.23 shows the impact of yearly production rate on price. The lowest

rates shown on the charm represent typical current rates, which were used to

determine the initial cost of -the present and advanced technology aircraft of

469 between rates of 0 and

this study. Category I aircraft prices drop by 60

40% between rates of 300 and 100,000.

100,G00. Those of Category II drop by

between rates of 200 and 100,000 and these

Those of Category III drop by 37^

an.t, 100,000 per year. Rates as high as

50% between 150

of Category IV drop by

100,000 per year are probably not realistic for any single manufacturer, even

for Category I aircraft in the 1985 time period. However, the drop in price

due to volume stresses the importance of producing high performance, quiet, utilitarian aircraft design for low production cost.

1-4o

• FIGURE 6 k (_,L^

FIGURE WK1 AVLoW

T w 1`406E

EPEE 0 TECHNOLOC1 1 `

r

PkIc! V^ 1- PEEU P ^E1r ti

n :T A'EI': y H# ,PEER

(^ LE`^ELi r_ T4 PRICE PROLIV

%8.25 fi H

24 IrAUVAtYCkU 1j^ L^Cv'^ AINCAAkT,I

t , . EC l

i

4AC L a O4 i AVIONICw A

Jl 1910 EICISTIN(i AIRPLANE PFi E ffI 1tiL! PRICE 1$1000) CAT EL,^ES 300 . —_. - - ^vBS HELIt;t^PTEGS

P

III -

1 1 0 *0 TURBINE

-

' r

+ELICvPIER^

r / 1

il4 Q 19Li5 ! IUIET

/ I

___ 1 ENO.

AfRPtANis / RICIP, 1993 AIRPLANE « , , 1 7 " 1910 EXISTING AIRPLANE`.+ 1970 QUIET AIRPLA NE S Iv/W w ECIP,.

Ij k^ 1LIC^tRfiER'^^/ // I^/ / --- SYMBOLi • 197() EATE"Ay I913 I - ENG. AOv. TtOiNuta'oc;* fiASE11NE / REfi1P; I AUV. AVIQNKC AFC x

O 1 • 0

II C! EXTRA A(FTY Plejv.

n A

r

A Q HkALT; PUI';E + PRE55Uk11Afl0tl* III r V — I •° JG'iNG A`91C^t1t` ,

"k'+^^ L I

d 113V :w IE W l5CK,^ 'w 4_+_1 'M 500 1" MO EMPTY WEIGHT h MAX. CRUISE 5PLEu EMPTY WEIGHT X MAX. CkUISE SPEED (I VW 0. -MI.,Hk0 (it" LB. -Mi.:tik.)

1.8.7 Sensitivity Summary

The graph of Figure 1.7.2 showed the present cost trend of contemporary aircraft

This trend is repeated in the graph

as a function of the weight-speed product.

of Figure 1.8-24, showing solid curves for contemporary airplanes and helicop-

The long dashed curve represents the present technology, quiet airplane

ters.

derived in this study, which exact a nigher price based on weight x speed. The

short dashed curve, representing advanced technology quiet airplanes, lies

between the other two. This shows that quiet airplanes (with also Letter air-

field performance) cost slightly more, per pound-mph, than contempurary air-

planes. The opposite effect is noted with helicopters and reflects the lower

cost of rotating combustion engines as compared with turbines. No avionic

equipment, is included in this comparison.

Figure 1.8.25 shows a similar graph, confined to the advanced technology air-

The airplanes of

craft of this study $ to show the effect of added provisions.

Categories S, II and III are joined, while the helicopters of Category IV are

isolated. The dashed curve, joining black dots, reflects the advanced tech-

The solid curve below represents those with high

nology baseline aircraft.

'

altitude capability, while the solid curve immediately above represents those

with extra safety provisions. The foregoing curves do not inclu&- avionics.

W

il 4

The highest curve for airplanes reflects the cost of advanced avionics and

flight control, with the capability varying from VFR with accurate navigation

aide in Category I 9 to minimum capability IM in Category II and maximum

capability IFR in Categories III and IV.

The effects brought out in the sensitivity analyses are instrumental in

choosing the recommended configurations, which follow.

1-41

AND COMIARI'JON BET'A"EEN PECOMMENOED FIGURE 1.9.2 BASELINE CONFIGURATIONS, CATEGORY I FIGURE 1, 9.1 3.0 (100^O LBS) 15 (^/MILE) ARRANGEMENT GENERAL B - 1970 BASELINE A - 1985 BASELINE CAT. I RECOMMENDED CONFIG.

R - RECOMMEND.

B 2.5 25 ($1U00) A A bR , _ R R (H. P.)

200 20 2.0 10- R A R A 15 7.5- t 1.0- 100 WT.

EMPTY 0.5 * 50 2.5 A WEIGHT POWER COST PRICE OPERATING 300 HRS/YR 1.9 Recommended Configurations Tentative recommendations of promising aircraft configurations in each c.11.te- 4.

gory are made by combining the results of the sensitivity analyses and recon figuring the advanced technology baseline aircraft into designs which the investigators feel will provide the maximum stimulus to the use of general This is one of the principal objectives of the study aviation in the future.

the other being "how to get there."

1.9.1 Category I Several combinations were examined in this category before a sound recommenda- tion could be made. They included a combination of advanced avionics and extra system safety provisions, while retaining the same speed and range, but PNdB noise level requirement was raising the field length to ft. The 1 500 retained. 'phis resulted in a price increase, with increased operating cost.

The logical direction 'to take in providing a privately owned airplane with increased popularity is to make it more useful to the owner. Therefore, the utility and convenience features brought out in the technology investigation were examined for application. It was found possible to combine the features of wing folding, towability and all-terrain capability with the pusher propeller configuration without serious compromise. The result is shown in Figure 1.9.1.

performance, an extra In the area of 1,500 500 ft . of field length ( to ft.)

and 100 miles less of range ( to 400 miles) was traded for s;1 extra 10 knots of kta or mph). This results in a smaller, easily ork:14se speed (to 155 1 78 handled aircraft that can be "garaged" at home and towed to any available clearing or waterway for flight operL ,,tion.- Economically, the price is about the same and the operating cost is about less. Figure 6% shows its com- 1-2.2 parison to the present and advanced technology baseline airplanes in Category I.

COMPARISON BETWEEN RECCOMMLNDED AND

FIGURE 1.9.4

FIGURE 1.9.3

BASELINE CONFIGURATIONS, CATEGORY yI .GENERAL ARRANGEMENT B

CAT. II RECOMMENDED CONFIG. B - 1970 BASELINE

-- 120 ($ 1000) - 1000 FT. R A - 1985 BASELINE R - RECOMMEND.

B B A 5.0 (1000 LBS): . 500 (H.P.)_ 100 -^---- 500 -- H B GR,DIS.

4.0- - 400 FIELD LENGT4-1 A k M I LF) ' B R 3.0 — 300 60 R R in, A 20 R 2.0 200 N it WT.

20 1.0

1 1 I I

OPERATING COST WEIGHT POWER PRICE 300 Hb//YR 1.9.2 Category II This aircraft is classified as STOL, which implies operation between areas of deasu population, to and from close-in airfields, as well as in "bush" country and from high altitude airfields. STOL performance, as such, has never been expressed in terms of a definite field length or minimum flight speed, both of which increase with the size and weight of the airplane. While a field length of 500 ft. was specified by NASA, it is believed that minimum length STOL strips are, and will continue to be, at least 1000 ft. in length to accommo- date medium-to-large aircraft. Therefore, it was considered expedient to trade the extra 500 ft. for other desirable capabilities; namely, extra system safety provisions, advanced avionics and automatic flight control, with IFR capability.

Another desirable feature is high altitude cruise capability, which was found to be a weight, power and cost reduction item. No compromises with range and noise level are recommended.

The resulting configuration is illustrated in Fi gure 1.9.3, and it is compared with the present and advanced techaology baseline aircraft in Figure 1.9.4.

The initial cost is only 11% higi;er than that of the 1985 baseline and is 59% Lower than that of the 1970 baseline. The operating cost is lower than that of either. Although this airplane is priced in the realm of the business operator, it should be attractive to a small segment of private owners, as well. Its high degree of utility should result in higher-than-average utilization, with correspondingly lower operating costs.

j 1-43

FIGURE 1.9.5 GENERAL ARRANGEMENT CAT. III RECOMMENDED CONFIG.

ROSS WE^GM^ ^^ ?328 Lb, t rt AiNG AREA 19-) - i7 MA E. NGWNE H. P 31)i PPOPELLER DiAM 9?8 F W: N5 ASPECt R4^J 8 c 07u W Nu1APER R^turro *INGSWt 025C 0 ..1.

1.9.3 Category III Thie airplane is designed for the corporate owner in the medium-to-large business bracket. His requirements call for long range operation at high cruiBing speeds, use of medium length airstrips, a comfortable interior -- but, above all, a high degree of schedule reliability with maximum independence of weather.

tha baseli aircraft in Category III is the The principal objection to ne abnormally large propellerso the propell-or diameter can be reduced to an acceptable size by raiaing the exte-xrxal noise level and increasing the field

length. Increments of 10 °:" 8 Inc -'. ,)0 ft., respectively, result in a level of

which are compatible with the satellite "i-e-Ld length, 85 PNdB and a 2000 ft.

airfields from which the riajority of operation would occur. Trading these increments for advanced avionics and flight control, plus extra structural and system safety provisions, results in the compact, attractive configuration shown ix Figure 1.9.5. It is compared with the present and advanced technology which shows competitive price and operating baseline aircraft in Figure 1.9.6 9 cost with, respect to the latter.

1-44

URE 6 FIG 1.9.

COMPARISON BETWEEN RECOMMENDED AND BASELINE CONFIGURATIONS, CATEGORY III R B A B - 1970 BASELINE A - 198, BASELINE ADV.

NONE NONE R - RECOMMEND. ^ (A) AVIONICS & FLIGHT CONTROL A A R B (1000 LBS) (1000 1.0 10.0 I 85 ^^ 75 75 H. P.)

B BASIC BASIC EXTRA PNdb I P1ldb PNdb NOISE LEVEL - 500 FT.

SAFETY PROVISIONS 8.0 0.8 R ($1000) — 80 _WMILE) --200,0 FT, R A R IB pm B B A 0.6 6.0 A 300 60 R — 1500 R s 4.0 — 1000 0.4 20'0 40 A };r„ WT.

t ^.

EMPTY , GR.DIS.

100 20 0.2 2.0 500 > ;:: r,{s TIGHT POWER FIELD LENGTH PRICE OPERATING COST 300 HRS/YR Increasing the noise level to 85 PNdB admits reconsideration of the turbofan candidate described in Section 1.8.6 1 which provides a 20% increase in cruise speed. In comparison to the recommended propeller aircraft, it lacks the more to buy and 26% advanced avionics and extra safety provisions, costs 5.5% more to operate. Inclusion of these items would widen the cost gap considerably.

Nevertheless f the turbofan or perhaps a compromise "prop-fan" design might appeal to a considerable segment of the market.

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COMPARISON BETWEEN RECOMMENDED AND FIGURE 1.9.7 BASELINE CONFIGURATIONS, CATEGORY IV 6.0 (1000 LBS) 300 ($,'MILE) ($1000) •-- 1.50 B B - 1970 BASELINE B B A R B A - 1985 BASELINE R R - RECOMMEND.

BASIC I BASIC I EXTRA 1.25 5.0 PROVISIONS NOISE LEVEL SAFETY 75 PNdb AT 500 FT. (ALL) R A ONE ^NONEI (V.]

1.00 4.0 200 R H AVIONICS & FLIGHT CONTROL ,_ B (KNOTS) A 0.75 600n (H. P.) 150 150 3.0- R A R (STAT. MI.)

2, 400 100 100 - 0.50 500 B A W T.

EMPTY 200 250 R 50 - 0.25 ` - 50 1.0 p GE PRICE OPERATING COST CRUISE SPEED RAN WEIGHT p -=' _¢' 300 HRS/YR 1.9.4 CategoryV The helicopter configuration, selected for Category IV, is designed primarily for the business owner whose principal transportation problem is rapid transit, within a metropolitan area or between closely spaced areas of dense population.

He would like to dispense with ground travel altogether, making use of "heli.- pads" on roof tops, in city parks and other convenient locations including parking lots. To become fully accepted by the public, the aircraft must have a. low external noise level. To be fully useful to the operator, it must have all-weather capability and extra safety provisions - the latter being due to flight in a forest of obstacles. The operator should be willing to accept a slightly lower cruise speed and possibly a shorter range in trade for the additional provisions, since these characteristics will not seriously impede his operations. Operation at longer ranges, such as between the parking lots of i.ndus',rial plants, might be desirable, however.

The recommended configuration trades a 5 knot reduction in cruise speed (to 135 kts) and a 250 mile reduction in range (to 250 miles) for the advanced avionics, automatic flight control and extra safety features. It results in a czaft of the same size as that of the advanced technology baseline, hence Figure 1.8.8 is applicable. Its comparison wit' that design shows a 36% higher price and 30% higher operating cost, though the latter might become lower due to higher utilization.

1-46

FIGURE 1.10.1 FIGURE 1. 10.2 AIRS RAFT PAS) & PRCUECTEU OLNERAL AVIATION PRICE CLASSIFICATIONS OF GENERAL AVIATION AIRCRAFT UELIVERFES PER YEAR DELIVEkED IN 1969 AND THEW RELATIONSHIP TO CATEGORIES 1, II 3 III, IV (EXCLUL)ING kVIONICS) tee IJ__ 1.10 Projection of 1985 General Aviation Use Potential 1.10.1 Price/Quantity Relationship study, the effect of yearly production For the aircraft derived in this quantity on price was discussed in Section 1.8.16 and illustrated in Figure 1.8.23. This action attempts to analyze the effect of price ou marketable i quantities. This is an example of the "chicken and egg" question - which comps first, price or quan-6itj? Even if aircraft were sold in comparable quantities to automobiles, their higher cost-per-pound (by a factor of about 6) would cause their unit cost to exceed that of medium priced automobiles by a factor of about 2.8. While even this relationship would stimulate the market, a yearly quantity of 100,000 for a single model would represent about one--third of the entire fleet forecasted for 198;, hence is highly optimistic.

The annual delivery rate, projected to 1985, was derived from Ref. 1.7 and is shown in Figure 1.10.1, Despite the recent recession, the production rate for all aircraft might reach 60,000 by 1985.

Figure 1.10.2 shows a breakdown into price groups and the relationship to 4A1 aircraft in Categories I, II, III and IV. These combine to represent t of the total general aviation market by number of aircraft, with Category 5f, and Categories III I accounting for 30%, Category II accounting for and IV combined representing` '5f. Applying these percentages to the 60,000 per year forecast for 1985, we can foresee 18,000 in Category I, along with .et.: 3000 in Category II, and 3000 in Categories III and IV combined. By reference to Figure 1.8.27, and assuming 1 model in Categories I and II will account for one-third of the total, we can establish price tags of $11,000 for Category I and $39,000 for Category II. Assuming Categories III and IV split their share of the market and a specific model of each category will account for one-third of the' sales, would indicate a production, rate of 500 vehicles, Thia gives a selling price of $153,000 for Category III and $130,000 for Category IV.

1 -47

1.14.2 Growth Constraints 1970- The growth in general aviation aircraft deliveries forecasted for the is unconstrained by adverse factors.

period represents a potential which 19d5 Warnings, however, have been given citing forces at work which could reduce this potential to a much smaller figure. The principal constraints appear to be declining utilization, insufficient emphasis on educaticei, airport satura- tion and air traffic regulations.

With regard to utilization, the average yearly figure for all pilots is about showed a rapidly increasing cost of operating any 1.7.4 130 hours. Figure aircraft less than X00 hours per year. New uses must be found for, and greater convenience must be designed into, personal aircraft. L'uslaiess aircraft must be designed for increased sonedule ava'..lability, and some should have the ability to use close-in airfield:. Noise and pollution objections must be overcome. The growth of business flying during the 1960's was less than that of the GNP, wh oh is an indication of utilization far below its potential..

The subject of education includes attracting new pilots in growing numbers, showing business managers how they can operate aircraft profitably, and pro- moting safety features. Even with increased utility and .-educational programs, the potential growth of general aviation can be hamstrung in the future by 7 1 000 airports in the U.S. are airport saturation. Surveys show that only increase is required before available to the public and that at least a 33% general aviation can begin to realize its growth potential. Inexpensive, l located close to residential and business areas can unpaved airstripa partially fill the gap, provided that aircraft with low noise levels, minimum air pollution and high flotation landing gear are made available. The adop- tion of the air cushion landing system would make waterways available as well..

Air traffic regulations, governed by the FAA, are becoming more complicated with the increase of traffic; density, particularly within metropolitan areas.

Air traffic control must move in the direction of simplici*Py, otherwise existing and potential pilots will lose their initiative. Stricter pilot a licensing requirements will have a similar effect. Safety must be promoted by educational procecies ratter than regulatory complexity.

1.11 Conclusions 1.11.1 Specific Conclusions Category I aircraft which are directed toward individual and small business ownership, must be designed primarily for a combination of high utility and low price. Foldable wings are recommended for home storage and roadability and the air cushion landing system for all-terrain operation. Their external ft. and their internal noise level 75 PNdB at 500 noise level should not exceed and visibility can be optimized with a pusher propeller installation. Their field length should not exceed 1,500 ft., their cruise speed should be clone to 150 knots, and their range not less than 400 miles. As in the case of the other three categories, the rotating combustion engine appears to be the ideal power plant.

Category II aircraft are intended for STOL operation in and out of close-in is there- airfields, and are directed primarily toward business ownership. It fore necessary to provide high cruise speed (200 'snots minimum), adequate range (500 miles minimum), 1000 ft. maximum field length and not over a 75,PNdB noise level at 500 ft. Schedule reliability should be provided by the instillation of advanced avionics, with IFR capability automatic flight control and extra safety provisions. A high level of comfort should be provided by use of vibration-free rotating combustion engine, pusher propeller and cabin pres- surization. This type of airplane can be priced at about $50,000.

j 1_48

Category III aircraft are intended for use by the small to medium business owner primarily for long range, intercity operation. This requires a minimum cruise range of 1 9 500 miles, and a minimum cruise speed of 250 knots. Opera- tion from 2 1 000 ft. airfields, with a maximum exterior noise level of 65 PNdB at 500 ft. is considered feasible. Cabin pressurization, advanced avionics, automatic flight control and extra safety provisions are recommended. The configuration can take two forms: a high wing twin engine - propeller or a single turbofan engine installation, with the price tag held in the range of $150,000 to $200,OOU.

Category Iv aircraft comprise the VTOL segment of general aviation, directed primarily .'or business use because of cost considerations. They are intended for opera4..ion primarily within metropolitan areas, hence speed and range requirements should be subordinated to more necessary features. The helicopter should continue to play this role, since fixed wing VTOL concepts appear too expensive for general aviation. The 75 PNdB noise level is maximum for down- town operation and is not penalizing. Advanced avionics, automatic flight control and extra safety features are recommended for maximum utilization.

pay- Cruise speed can be ea low as 135 knots and a range of 250 miles with full load might be adequate. This combination will hold the price to around $200,000, resulting in a substantial, but relatively low volume, market.

1.11.2 General Conclusions The impact of advanced technology can improve the utility, dependability and safety of general aviation aircraft, while simultaneously lowering,° initial acid operating costs. This area includes aerod ynamic design, propulsion systems, avionics, structural design, safety provisions, special utility and convenience features and V/STOL technology. The most promising litres of development include quiet propellers, the rotating combustion engirie, the air cushion — landing system, the use of low cost composite materials and associated processing, and the development of low cost, reliable avionics. Improved handling qualities though not specifically address in this study should be sought by continued research and development.

Environmental factors, which include pollution of the air by noise and noxious gases, will constrain the growth of general aviation by regulatory processes unless the industry will face up squarely to the problems. The noise problem can be solved without serious penalty, as shown in this study.

engine manufacturers Pollution control is receiving widespread attention by the is expected to reach a satisfactory level by 1975.

and Educational programs must be increased in tempo. These include the accelera- tion of pilot training, the economics of business ownership and convincing the public of the safety and environmental compatibility of general aviation aircraft.

Airfield and service facilities must be increased to sustain the growth of general aviation. Convenient locations must be emphasized. Government financial aid to small and large communities is necessary. Such aid can be tied in with noise and air pollution standards.

Federal Air Regulations must be tailored to promote the growth of general " aviation, while maintaining a high standard of safety. Traffic regulations need to be simplified, rather than complicated. Higher standards for handling qualities should be established, applicable to all general aviation aircraft.

1 -49

FIGURE 1.12.1 FIGURE 1. 12.2 RECOMMENDED AIRCRAFT R&D AREAS RECOMMENDED PROPULSION AND AVIONICS R&D AREAS STRUCTURAL DESIGN STUDY OF A REPRESENTATIVE PROPULSION AIRPLANE, USING COMPOSITE MATERIALS o DEVELOP, TEST AND CERTIFY A ROTATING COMBUS1101 4 J ENGINE WITH NOISE AND DETAILED STUDY AND ACTUAL INSTALLATION OF EMISSION CONSTRAINTS AN RC ENGINE, DRIVING A QUIET PROPELLER e DEVELOP, TEST AND CERTIFY A LOW NOISE Ih1PROVED HANDLING QUALITIES PROGRAM FOR A O LEVEL PROPELLER DESIGNED FOR LIGHT REPRESENTATIVE AIRPLANE, PHASED INTO STUDY, WEIGHT AND LOW COST.

4 ST, SIMULATION AND FLIGHT TEST WIND TUNNEL AVIONICS SEPARATE DETAILED STUDIES TO INCLUDE e FOLLOW STUDY OF CONTROL-CONFIGURED - ,A CONTROL-CONFIGURED ,AIRPLANE AIRPLANE WITH DEVELOPMENT OF APPLICABLE - APPLICATION OF THE AIR CUSHION LANDING SYSTEM EQUIPMENT FOR FLIGHT RESEARCH.

VTOL AND STOL APPLICATIONS - TUn0FAN VS. PROP-FAN - 1.12 Recommendations 1.12.1 Recommended Aircraft R&D Areas The first concern is the provision of support in the development of usable advanced technology. The prime areas listed in Figure 1.12.1 comprise an initial approach to the development of better aircraft. Hopefully, the results will generate further R&D effort, which the industry will use to best advantage.

The first item suggests a study similar to the previous one by San Diego Aircraft Engineering but making economical use of more advanced composites and confining the study to one particular model. The second study item would aloo utilize advanced technology in both the engine and propeller and would also be confined to one particular aircraft. This would follow a current effort along this line. In the third item, it is recognized that considerable effort is being directed toward improving the handling qualities of small aircraft.

This recommendation, however, would project the study toward full utilization of advanced technology.

The last block includes several items. The study of a control-configured airplane implies the use of an automatic flight control system, with attendant avionics in an effort tcward achieving all-weather flight capability. The study of an air cushion landing system application would pick up the existing technology and project it into the 1980 1 x. The V/STOL applications would be directed toward recommedning optimum configurations for the missions. Finally, the turbofan and prop-fan propulsion systems would be optim:^zed for comparison with the engine-propeller configuration.

1.12.2 Recommended Propulsion and Avionics R&D Areas Aircraft development, in itself, is not sufficient, and parallel efforts must be made in related fields. Two of the most important are the areas of propul- sion and avionics, as listed in Figure 1.12.2.

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FIGURE 1.1x.3 GENERAL AVIATION NON-TECHNICAL CONSTRAINT STUDIES AIRFIPLD AND SERVICE I`ACILITIES SURVEY AND ORDERLY EXPANSION PROGRAM o FEDERAL AIR REGULATIONS, AS AFFECTED BY EMERGING TECHNOLOGY, TRAFFIC DENSITY, ENVIRONMENTAL CONSIDERATIONS, ETC .

b LICENSED P I LOT AVAILABILITY SURVEY, FORECAST AND EDUCATIONAL PROGRAMS GENERAL FORECAST FOR GENERAL AVIATION, TO 1985, ASSESSING THE IMPACT OF ALL PERTINENT FACTORS.

Propulsion development must be directed toward penetration of the cost, noise, and pollution barriers. Since the rotating combustion type of engine appears to be a clear choice for general aviation aircraft of the future, it requires detail;d development for this application. The power rating of the engine can the most popular category of aircraft in which it be determined by assessing wo,ild be used - probably Category I oe this study. The propeller would be same application.

designed for the Avionics development mw, t be aimed at lower cost, greater capability', and nigher reliability. The control-configured airplane would evolve from the previously suggested study, but an available airplane with similar flight characteristics could be used for flight research.

1.12.3 General Aviation Non-Technical Constraint Studies No matter what degree of technical improvement can be achieved in aircraft and related systemb, there are other areas which must be addressed if general aviation is to have substantial growth in the future. These areas have been 1.12.3 lists some definite action which can previously discussed, and F'igaEe be taken to provide support. The last item would be timed to follow the tech- nical studies and the foregoing areas listed above.

References 1.1 Drake, H. M., Kenyon, G. C., and Galloway, T. L.: "Mission Analysis of 1970'x," AIAA Paper 69 -818, July 1969.

General Aviation in the 1.2 Anon: "Potential Structural Materials and Design Concepts for Light Aircraft," San Diego Aircraft Engineering, Inc., NASA CR-1285 9 March 1969.

1.3 Hurkamp, C. H., Johnston, W. M., and Wilson, J. H.: "Technology Assessment of Advanced General Aviation Aircraft" (Final Report , Lockheed-Georgia Company, NASA CR- 114339, June 1971 1.4 NASA Ames Research Center, Contract "Technology Assessment of NAS2-5972: Advanced General Aviation Aircraft," June 15, 1970.

1.5 Worcbel, R., and Mayo, M. G.: "Advanced General Aviation Propeller Study," Hamilton Standard Division of United Aircraft Corporation, NASA CR-114289, i April 1971.

1.6 DOT/FAA Office of Policy Development: "General Aviation Operation Costs," February 1969.

1.7 R. Dixon Speas Associates, "The Magnitude and Economic Impact of General Aviation, 1968 - 1980, 11 Report , for LAMA, 1-51