1. Compound Aircraft Transport 1) Mx – 1018 project B-29/F-84 2) Tom-Tom Project B-36F/F-84 Model Problems of Compound Flight Configuration IConfiguration II C-5 C-27

2. Compound Aircraft Transport Wind Tunnel Tests Vortex Lattice Calculations Water Tunnel Flight Controls Propulsion Studies Finite Element Structures Tools and Facilities

3. Compound Aircraft Transport Calculated C-5 / C-27 Drag Coefficients -Induced drag reduction as tips approach each other d

4. Compound Aircraft Transport

5. 0 0.2 0.4 0.6 0.8 1 1.2 00.20.40.60.811.2 Scale of Hitchhiker System Range Ratio Effect of Hitchhiker Size on Range

6. Compound Aircraft Transport Mothership/Hitchhiker Attached by Hinge Carbon Fiber/foam fixed wing Balsa wood hinged wing (NACA 63-420 airfoil) has option to add varying masses to the tip of the hinged wing Wind Tunnel Experiment

7. Compound Aircraft Transport In plane bending ( New mode) Normal mode analysis of C-5/C-27 C-5 Solo 1 st Bending Mode 1.4 Hz Mode # 1. Torsion, 0.25 HzMode # 3. In plane bending, 0.53 HzMode # 2. Bending, 0.50 Hz Mode # 4. Bending, 1.20 Hz Mode # 5. In plane ending, 2.11 Hz

8. Compound Aircraft Transport T HH /T HHsolo =1.275 T HH /T HHsolo =1.0 T HH /T HHsolo =0.0 Compound Aircraft Transport Minimal fuel consumption Beta: mother ship drag benefit a: Hitchhiker drag benefit

9. Compound Aircraft Transport C-5/C-27 Combined Maximum stress shifted closer to the tip FE Static Analysis Maximum stress lb/ft 2

10. Compound Aircraft Transport All Aircraft get Lift Benefit and Drag Reduction - Attached Flight: system drag is less than mother ship alone - Formation flight: hitchhiker benefits in lift and drag - Optimal position: hitchhiker behind, inboard and above mother ship wing

11. Compound Aircraft Transport Attached hitchhikers ride stably and with minimal control - Hinged connection should be stable with no need for active control - Hitchhikers may turn engines off or operate at low throttle

12. Compound Aircraft Transport  Local minimum fuel consumption can be achieved with:  transport providing all thrust or  by splitting thrust between transport and hitchhiker T HH /T HHsolo =1.275 T HH /T HHsolo =1.0 T HH /T HHsolo =0.0 Minimum fuel consumption 0 0.2 0.4 0.6 0.8 1 1.2 00.20.40.60.811.2 Scale of Hitchhiker System Range Ratio  Hitchhikers ride for free and may even chip in gas.  Mother ship may save fuel. Significant fuel savings

13. Compound Aircraft Transport Structural modifications are needed to improve the static and dynamic response of the compound - Maximum stress shifted towards the tip of the wing - Presence of new normal modes of the compound system Problems can be solved by structural reinforcement and/or controls

14. Compound Aircraft Transport Attached or in Formation ? Attached: - a little greater drag benefit - with hitchhiker engines off, significant increase in range - stable and safe flight with no controls Formation: -flight control nightmare - requires running VSTOL engines that are inefficient for high speeds

15. Compound Aircraft Transport o Wind tunnel tests with hinged attached models o Measure forces and moments o Measure unsteady pressures on wing models o Monitor the wakes with high frequency-response 7- hole probes o Study the flow field with particle-image velocimetry o Model the dynamics of hinged aircraft motion o Couple aerodynamics with structural codes to predict aeroelastic behavior o Employ the codes thus develop in design.

16. Compound Aircraft Transport Structural analysis and design  Detailed high fidelity analysis of compound aircraft configurations  Steady and unsteady aeroelastic analysis  Identification of cost effective structural modification for existing aircraft  Development of design tools for new aircraft designed specifically for compound flight  Propulsion  Expand current engine fuel consumption analysis to account for various sized transport and hitchhikers.  Develop engine models to allow examination of engine configurations to allow high bleed flow rates.  Integrated computational/experimental study of the aerodynamics of a CAT  Design code for required camber /twist and simulation using devices

17. Compound Aircraft Transport  Multidisciplinary Design and Optimization (MDO)  Evaluation of MDO platforms (e.g. Model Center: Phoenix Integration, insight: Ingenious Software)  Parametric detailed (realistic) structural analysis models for MDO  Identification and coordination of systems and subsystems variables for MDO  Response surface models for representation of disciplines within the MDO