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AAE450 Spring 2009
Final SlidesLunar Lander Structure
April 9, 2009
Lunar Descent Phase Group
[Ryan Nelson] [STRC]1
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AAE450 Spring 2009
Basic Frame Design Drivers in frame mass
– Total Lunar Lander (LL) mass at lunar touchdown
– Volume of LL
Shape: Conic Frustum– Stores all Lunar Lander subsystems
while minimizing volume
All frame components hollow– Small leg diameter allows for storage
within side supports prior to lunar touchdown
Schematic of frame listing components
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AAE450 Spring 2009
Backup Slides (Mass/Volume)
Lunar Lander Volume Height Top Diameter Bottom Diameter Mass
100g 1.05 m3 1.0 m 1.0 m 1.3 m 11.44 kg
10kg 1.15 m3 1.1 m 1.0 m 1.3 m 19.97 kg
Large 14.33 m3 2.0 m 2.4 m 3.6 m 104.86 kg
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AAE450 Spring 2009
Backup Slides (Frame Design) Thickness of all frame components varies
– First mode of failure (factor of safety = 1.5)– Payload case
Cross sectional shape is circular or rectangular for all components
0.5 mm magnesium skin place around Lunar Lander frame– Micrometeorite protection– Thermal protection
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AAE450 Spring 2009
Backup Slides (Floor Supports) Support a majority of landing loads
Thickness altered until load is supported Hollow Rectangular Cross section
– Moment of Inertia
– Bending Stress acting on beam
I
My
I
My
12
)2)(2( 33 thtbbhI
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AAE450 Spring 2009
Backup Slides (Side Supports/Legs)
First mode of failure is buckling
– K=0.5 for side supports (both ends fixed)– K=2.0 for legs (one end is free to move)– Hollowing the rod decreases moment of
Inertia and critical load
2(kl)
EI
2(kl)
EIFcr =
)( 21
22 rrI
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AAE450 Spring 2009
Backup Slides (Side Supports/Legs)
Compression failure occurs after buckling for both side supports and legs– Despite small cross sectional area– Compression failure
Top, Bottom, and Engine Support rings all designed to have same cross sectional dimensions
A
F
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AAE450 Spring 2009
Backup Slides (Cross Sectional Dimensions)
100g Payload CaseStructural Component Cross sectional shape Outer Dimensions Thickness
Outer Ring Circular 10 cm Diameter 4mm
Engine Support Ring Circular 10 cm Diameter 4mm
Rectangular Floor Supports Rectangular 10 cm Height, 6 cm Width 6mm
Side Supports Circular 10 cm Diameter 2mm
Top Ring Circular 10 cm Diameter 4mm
Legs Circular 6 cm Diameter 3mm
10kg Payload CaseStructural Component Cross sectional shape Outer Dimensions Thickness
Outer Ring Circular 10 cm Diameter 5mm
Engine support Ring Circular 10 cm Diameter 5mm
Rectangular Floor supports Rectangular 10 cm Height, 6 cm Width 7mm
Side supports Circular 10 cm Diameter 2mm
Top Ring Circular 10 cm Diameter 5mm
Legs Circular 5 cm Diameter 3mm
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