1) Mx

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Model Problems of Compound Flight
Configuration I
Configuration II

• 1) Mx 1018 project
• B-29/F-84
• 2) Tom-Tom Project
• B-36F/F-84

C-27
C-5
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Wind Tunnel Tests
Tools and Facilities
Finite Element Structures
Flight Controls
Propulsion Studies
Water Tunnel

• Vortex Lattice Calculations

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Calculated C-5 / C-27 Drag Coefficients
d

• Induced drag reduction as tips approach each other

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(No Transcript)
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Effect of Hitchhiker Size on Range
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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
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Normal mode analysis of C-5/C-27C-5 Solo 1st
Bending Mode 1.4 Hz
In plane bending ( New mode)
Mode 1. Torsion , 0.25 Hz
Mode 3. In plane bending , 0.53 Hz
Mode 2. Bending , 0.50 Hz
Mode 4. Bending , 1.20 Hz
Mode 5. In plane ending , 2.11 Hz
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THH/THHsolo1.275
THH/THHsolo1.0
THH/THHsolo0.0
Minimal fuel consumption
Beta mother ship drag benefit a Hitchhiker
drag benefit
Compound Aircraft Transport
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FE Static Analysis
C-5/C-27 Combined
lb/ft2
Maximum stress
Maximum stress shifted closer to the tip
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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
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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

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Significant fuel savings

• Hitchhikers ride for free and may even chip in
  gas.
• Mother ship may save fuel.

• Local minimum fuel consumption can be achieved
  with
• transport providing all thrust
• or
• by splitting thrust between transport and
  hitchhiker

Compound Aircraft Transport
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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
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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

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• 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.
•  

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• 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

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        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