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

Compound Aircraft TransportCompound Aircraft Transport

1) Mx – 1018 project

B-29/F-84

2) Tom-Tom Project

B-36F/F-84

Model Problems of Compound Flight

Configuration I Configuration II

C-5

C-27


Wind Tunnel Tests

Vortex Lattice Calculations Water Tunnel

Flight Controls

Propulsion Studies

Finite Element Structures

Tools and Facilities


Calculated C-5 / C-27 Drag Coefficients

- Induced drag reduction as tips approach each other

d


L/D vs. with = = 0.0 deg. and Streamwise Displacement,

=1.7

at a CL ~ 0.42 of a Solo F-84 and Vertical Displacements,

0

1

2

3

4

5

6

7

8

9

-0.4 -0.2 0 0.2 0.4 0.6

, Spanwise Locations

(L/D

)/(L

/D) s

olo

is w rt: origin tip-to-tip, + above and - below Transport Wing

Tip-to-Tip

*() = (X/c2, Y/c2, Z/c2)c2 = Average chord of F-84

L/D solo = 17.9


0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2

Scale of Hitchhiker

System Range Ratio

Effect of Hitchhiker Size on Range


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


In plane bending

( New mode)

Normal mode analysis of C-5/C-27C-5 Solo 1st Bending Mode 1.4 Hz

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


Total Formation Fuel Flow - 4 HH engines

0.5

0.6

0.7

0.8

0.9

1.0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

C5 Thrust / C5 Solo Thrust

Fu

el F

low

/ S

olo

Fu

el F

low

beta=0.20, b/a=1.5

beta=0.20, b/a=1.0

beta=0.20, b/a=0.5

THH/THHsolo=1.275

THH/THHsolo=1.0

THH/THHsolo=0.0


Minimal fuel consumptionBeta: mother ship drag benefita: Hitchhiker dragbenefit


C-5/C-27 Combined

Maximum stress shifted closer to the tip

FE Static Analysis

Maximum stress

lb/ft2


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

L/D vs. with = = 0.0 deg. and Streamwise Displacement,

=1.7

at a CL ~ 0.42 of a Solo F-84 and Vertical Displacements,

0

1

2

3

4

5

6

7

8

9

-0.4 -0.2 0 0.2 0.4 0.6

, Spanwise Locations

(L/D

)/(L

/D) s

olo

is w rt: origin tip-to-tip, + above and - below Transport Wing

Tip-to-Tip

*() = (X/c2, Y/c2, Z/c2)c2 = Average chord of F-84

L/D solo = 17.9


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

Compound Aircraft TransportCompound Aircraft TransportCompound Aircraft TransportCompound Aircraft Transport

Local minimum fuel consumption can be achieved with:

transport providing all thrust or

by splitting thrust between transport and hitchhiker

Total Formation Fuel Flow - 4 HH engines

0.5

0.6

0.7

0.8

0.9

1.0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

C5 Thrust / C5 Solo Thrust

Fuel

Flo

w /

Sol

o Fu

el F

low

beta=0.20, b/a=1.5

beta=0.20, b/a=1.0

beta=0.20, b/a=0.5

THH/THHsolo=1.275

THH/THHsolo=1.0

THH/THHsolo=0.0

Minimum fuel consumption

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2Scale of Hitchhiker

Sy

ste

m R

an

ge

Ra

tio

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

Significant fuel savings


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


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


•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.

•


• 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


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

Documents

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