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AAE450 Spring 2009 Kelly Leffel 3/26/09 Structures and Thermal Lunar Descent Phase Lander Integration Lander Thermal Control (Day) Kelly Leffel Structures and Thermal 1

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AAE450 Spring 2009 Thermal Control Day System MLI Blanket –Covers the outside of the lander, the propulsion system, and the space balls’ compartments (100 gram payload case) Heaters –Used on the propulsion system and the space balls’ compartment Cooling System –Aluminum Plate 0.1 m 2 Underneath communication equipment –Heat Pipes Ammonia working fluid –Radiators Used to radiate excess heat Kelly Leffel Structures and Thermal 2 Not to Scale

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AAE450 Spring 2009 Thermal Control Total Kelly Leffel Structures and Thermal 3 100 gram payload10 kg payloadArbitrary payload MLI blanket2.35 kg2.38 kg21.4 kg Heaters0.5 kg0.45 kg34.1 kg Cooling System6.72 kg6.73 kg1.03 kg TOTAL9.57 kg9.56 kg56.53 kg

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AAE450 Spring 2009 BACK-UP SLIDES Kelly Leffel Structures and Thermal 4 MLI Blanket Lander surface, propulsion system, and space balls’ compartments (100 g) 30 layers Aluminized Mylar (0.007 g/cm^2) Effective emissivity= 0.005 Q = e*(A)*sb*(Th^4-Tc^4) e = Effective emissivity = 0.005 A = Surface area (changes for each lander) sb = Stefan-Boltzmann constant = 5.67 *10^-8 J/K^4.m^2.s Th = Hot temperature (temperature in the sun) = 393 K Tc = Cold temperature (temperature in the lander) = 293 K Additional 0.4 kg on the 100 g case for the ball storage box

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AAE450 Spring 2009 Kelly Leffel Structures and Thermal 5 Heat needed to be removed Assume 70% efficient equipment With 40 Watts required, 12 Watts of heat released Communication Equipment Heat 100g – 49 Watts 10 kg – 38 Watts Arbitrary – 282 Watts

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AAE450 Spring 2009 Communication Equipment has a Max Temperature of 313 K, keep at 303 K as a factor of safety Keep Lander Operating Temperature around 293 K Similar Thermal Control as the OTV –Area of Plate : 0.1 m^2 –Aluminum (Al) thermal conductivity : 236 W/(m*K) –Al density: 2700 kg/m^3 –Thickness < AK(T 1 - T 2 )/q < 3.8 m (for both cases) Choose 0.5 cm ( 0.005 m) –Mass of plate = density * thickness * area = 1.4 kg Kelly Leffel Structures and Thermal 6 Aluminum Plate

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AAE450 Spring 2009 Ammonia Latent heat of vaporization of Ammonia: 1371 kJ/kg Mass (100 g) = 0.061 kW * 450 sec /(1371 kJ/kg) = 0.02 kg Mass (10 kg) = 0.050 kW * 450 sec /(1371 kJ/kg) = 0.017 kg Aluminum Heat Pipes (100g) Volume needed to simulate P=1 atm : 0.02313 m^3 Choose pipe of 5 m long 0.00463 m^2 cross sectional area pi*r i ^2 = 0.00463 m^2 : r i = 0.0384 m, r o = 0.0394 m Mass = 2700 * pi * (r o ^2 – r i ^2) * length = 3.3 kg Kelly Leffel Structures and Thermal 7 Heat Pipes

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AAE450 Spring 2009 Heat Pipe Continued Aluminum (10 kg) –Volume : 0.01532 m^3, choose length = 5 m –0.00306 m^2 cross sectional area –pi*r i ^2 = 0.00306 m^2 : r i = 0.0312 m, r o = 0.0322 m –Mass = 2700*pi*(0.0322^2-0.0312^2)*5 = 2.7 kg Radiators –Dissipate 61 and 50 Watts –Emissivity of 0.92 for white paint –Area of the radiators:0.1762 m^2(100 g) and 0.1444 m^2 (10kg) –Mass = 2.38kg(100 g), 1.95kg (10 kg) Kelly Leffel Structures and Thermal 8

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AAE450 Spring 2009 Overall Numbers Kelly Leffel Structures and Thermal 9 100 gram ComponentMass (kg) Dimensions (m) MLI blanket2.35lays on equip Al plate1.40.005 x 0.1 m 2 Heat pipe2.65 m, Ø 0.0560 Radiators2.7 0.005 x 0.311 x0.311 Ammonia0.021- Heaters 0.5 0.005 thick

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AAE450 Spring 2009 Kelly Leffel Structures and Thermal 10 10 kilogram ComponentMass (kg) Dimensions (m) MLI blanket2.38lays on equip Al plate1.40.005 x 0.1 m 2 Heat pipe2.515 m, Ø 0.0575 Radiators2.8 0.005 x 0.38 x0.38 Ammonia0.0215- Heaters 0.5 0.005 thick

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AAE450 Spring 2009 Arbitrary Kelly Leffel Structures and Thermal 11 ComponentMass (kg)Dimensions (m) MLI blanket 21.4 lays on equip Al plate 1.40.5 x 0.1 m^2 Heat pipe 10.5312 m, Ø 0.1039 Radiators 220.5 x 0.81 x 0.81 m Ammonia 0.1727 - Heaters 1.03 0.005 thick

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AAE450 Spring 2009 References Ryan Nelson for Lander Dimensions Adham Fakhry for MLI/hydrazine help Ian Meginnis for heat pipe help Spacecraft Thermal Control Handbook Volume I and II for Thermal Control data Robert Manning for MLI effective emissivity Kelly Leffel Structures and Thermal 12

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