AAE 450 Spring 2008

Vince Teixeira27 March 2008

StructuresNose Cone “Sarah”

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Nose Cone Design History Initial design consideration:

– Low Drag• Power-law body:• Sharp tip presents heating concern

Thermal Analysis– Stagnation point heating analysis

• As radius of curvature approaches 0, heating rate approaches infinity (infinite heat transfer to leading edge of nose cone)

• Simplified analysis using solid, blunted tip configuration

Structural loading– Axial compression

• Important considerations:– Stagnation pressure– G-loading

• Result: addition of 8 evenly-spaced stringers

AAE 450 Spring 2008Structures

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Heating and Pressure Analysis

Stagnation Point Heating Analysis– Driven by density of fluid, radius of curvature, instantaneous velocity, surface

temperature, atmospheric enthalpy

– High-altitude/low-density atmosphere drastically reduces heating• Still primary concern for nose cone requirements

Pressure Loading– Axial compression of nose cone

• Atmospheric loading due to stagnation pressure• G-loading of solid titanium tip• Axial stringers (Aluminum) added to increase strength

Materials– Solid nose tip: Titanium– Remaining surface: Titanium upper half/Aluminum 7075 lower half– Stringers: Aluminum 7075

AAE 450 Spring 2008Structures

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AAE 450 Spring 2008Structures

References Auman, Lamar M. and Wilks, Brett, “Supersonic and Hypersonic Minimum Drag for

Bodies of Revolution.” AIAA 2003-3417, Orlando, FL, June 2003.

Santos, W. F. N., “Leading Edge Bluntness Effects on Aerodynamic Heating and Drag of Power Law Body in Low-Density Hypersonic Flow,” AIAA Journal, Vol. XXVII, No. 3, 2005, pp. 236-242.

Schneider, Steven P., “Methods for Analysis of Preliminary Spacecraft Design,” AAE 450, Spacecraft Design, Purdue University

Aerospace Structural Metals Handbook, 2000 Edition

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Final Nose Cone Design

AAE 450 Spring 2008Structures

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AAE 450 Spring 2008

Final Nose Cone Masses

Launch Vehicle Mass (kg)

200g 1.7507

1kg 2.0435

5kg 1.7927

Nose Cone geometry/mass is a function of third stage diameter

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AAE 450 Spring 2008

Stagnation Point Heating Analysis

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0 10 20 30 40 50 60 70 80 900

1000

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6000

7000

8000

9000Enthalpy vs. Time for Proposed Trajectory

Time (sec)

Ent

halp

y (k

J/kg

)

Local enthalpy, ha

Enthalpy due to velocityTotal enthalpy, ho

Code co-written with Jason Darby

AAE 450 Spring 2008

Stagnation Pressure

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0 20 40 60 80 100 120 140 1600

200

400

600

800

1000

1200Pressure vs. Time for 5kg Payload

Time (sec)

Pre

ssur

e (P

a)

Atmospheric Pressure, Ps

Dynamic Pressure, qStagnation Pressure, P0