f /,W-.-o5 NASA Technical Memorandum 103988 Design Optimization of High-Speed Proprotor Aircraft David R. Schleicher, James D. Phillips, and Kevin B. Carbajal (NASA-TM-I03988) DESIGN N94-26151 OPTIMIZATION OF HIGH-SPEEO PROPROTOR AIRCRAFT (NASA) 4O p Unclas G3/05 0208973 April 1993 National Aeronautics and Space Adminisb'ation "TL_',.h.._ NASA Technical Memorandum 103988 Design Optimization of High-Speed Proprotor Aircraft David R. Schleicher, James D. Phillips, and Kevin B. Carbajal Ames Research Center, Moffett Field, California April 1993 I_d/LqA National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035-1000 Contents Page Summary ................................................................................................................................................................................ 1 Nomenclature ......................................................................................................................................................................... I 1. Introduction ................................................................................................................................................................. I 2. Configurations and Mission ....................................................................................................................................... 2 3. Aircraft Synthesls ........................................................................................................................................................ 2 3.1 Aircraft Sizing .................................................................................................................................................... 3 3.2 Aerodynamics ..................................................................................................................................................... 3 3.3 Propulsion ........................................................................................................................................................... 3 3.4 Weights ............................................................................................................................................................... 4 3.5 Mission Definition ............................................................................................................................................. 4 3.6 Numerical Optimization ..................................................................................................................................... 4 4. Assumptions ................................................................................................................................................................. 5 4.1 Tiltrotor .............................................................................................................................................................. 5 4.2 Tiltwing .............................................................................................................................................................. 6 4.3 Folding Tiltrotor ................................................................................................................................................. 7 5. Optimization ................................................................................................................................................................ 8 5.1 Design Parameters .............................................................................................................................................. 8 5.2 Constraints ......................................................................................................................................................... 8 5.3 Convergence ....................................................................................................................................................... 8 6. Current-Technology Results ...................................................................................................................................... 9 6.1 Design Tradeoffs ................................................................................................................................................ 9 6.2 Geometry ............................................................................................................................................................ 9 6.3 Weights ............................................................................................................................................................... 9 6.4 Drag .................................................................................................................................................................... 9 7. Advanced Technologies .............................................................................................................................................. 9 7.1 Technology Projections .................................................................................................................................... 10 7.2 Tiltrotor Results ............................................................................................................................................... 11 7.3 Tiltwing Results ............................................................................................................................................... 11 7.4 Folding Tiltrotor Results ........................................... _...................................................................................... 12 7.5 Comparison ...................................................................................................................................................... 12 8. All-Advanced-Aircraft Results ................................................................................................................................ 13 8.1 Design Tradeoffs .............................................................................................................................................. 13 8.2 Geometry and Performance .............................................................................................................................. 17 8.3 Weight ................................................................................. ............................................................................. 17 8.4 Drag .............................................. _................................................................................................................... 18 8.5 Gross Weight Sensitivities ............................................................................................................................... 18 o Disk Loading Trends ................................................................................................................................................ 18 10. Speed Trends ............................................................................................................................................................. 19 10.I Gross Weight vs. Cruise Speed ........................................................................................................................ 19 10.2 Productivity vs. Cruise Speed .......................................................................................................................... 19 10.3 Direct Operating Cost vs. Cruise Speed ........................................................................................................... 20 I.! PAGE_--_ INTENTIONALLYBLANK 111 P_ING PAGE BLANK NOT F_LMED 11. Concluding Remarks ................................................................................................................................................ 20 References ............................................................................................................................................................................ 21 Tables ................................................................................................................................................................................... 23 Figures ................................................................................................................................................................................. 27 iv Summary TAS true airspeed NASA's high-speed rotorcraft (HSRC) studies have the t/c thickness-to-chord ratio objective of investigating technology for vehicles that Yeng engine spanwise distance have both low downwash velocities and forward flight speed capability of up to 450 knots. This paper inves- tigates a tiltrotor, a tiltwing, and a folding tiltrotor 1. Introduction designed for a civil transport mission. Baseline aircraft Figure 1 illustrates the historical trend of disk loading models using current technology are developed for each versus cruise speed for vertical takeoff and landing configuration using a vertical/short takeoff and landing (VTOL) aircraft. The low disk loading aircraft, such as (V/STOL) aircraft design synthesis computer program to helicopters and tiltrotors, have the advantage of efficient generate converged vehicle designs. Sensitivity studies hover and low downwash velocities but tend to have low and numerical optimization are used to illustrate each cruise speeds. The high disk loading aircraft, such as configuration's key design tradeoffs and constraints. tiltwings and ducted fans, have higher