COEUS Brandon Adams Alex Hart Logan Sailer Ben Veenema Brandon Adams Alex Hart Logan Sailer Ben Veenema UAV for Titan 1

Project Goal “Design an aircraft for Titan’s atmosphere, focusing specifically on the cryogenic characteristics of composite-weave materials, and its implications for composite structures operating in a cryogenic environment.” Titan as base requirement 2

Project Objectives Characterize the material properties of carbon-cloth composites at cryogenic temperatures, including Axis-dependant Ultimate & Yield Tensile Strength Flexural Strength Impact Strength Axis-dependant Modulus of Elasticity Axis-dependant Coefficient of Thermal Expansion 3

Project Objectives Compile a catalogue of mechanical properties for various carbon-cloth/resin-matrix combinations in the cryogenic temperature regime Identify optimum cloth/resin combination to meet the loading requirements of an aircraft on Titan with a Lift-to-Drag ratio of at least 12 4

Project Objectives Identify an approximate parameter of mass to wing loading (kg-m2/N) for composite structures at cryogenic temperatures Develop a folding wing system to package an aircraft into a 2.6-m diameter aeroshell, and build a small prototype to demonstrate it 5

Specifications Aircraft must fit into a 2.6-m diameter aeroshell in order to be deliverable to Titan Material must provide sufficient strength for a wing loading of (TBD) as specified by flight requirements Composites will allow for a structure mass to wing loading parameter of [?] Concise cryogenic composite database 6

Metrics Packaged volume & length (wing span) of aircraft fits within aeroshell Wing loading effectively translated through joint Folding structure is self-deploying Material supports loading Mass < 300 kg 7

Metrics Cl, Cd, Cm, L/D Low Temperature [K] Change in Properties between 295 & 73 K [ΔMPa] Coefficient of Thermal Expansion [m/m-K] Internal stressing from thermal expansion [MPa] 8

Budget 20+ Samples, Silicon Temperature Diodes 9

Modeling ASSUMPTIONS Constant weight distribution Elliptical lift distribution Symmetric airfoil, constant skin thickness Idealized wing structural loading Booms - Axial only Skin (webs) - Shear only 10

Modeling Symmetric Airfoil - Booms & Skin Booms - Axial Loads Webs - Shear Loads 11

Calculations Kutta-Joukouski Elliptical Lift Span dependent Required for wing loading 200-kg Wing structure 100-kg Payload 12

Calculations Lift and Weight Distribution 13

Calculations Shearing force from wing tip 14

Experimental Modeling Flexural, tensile, impact testing [0 n ] - bidirectional ply Uniform temperature (no temperature gradient) Time-varying temperature Temperature-strain relationship Assume bi-symmetric material 15

Calculations Shear force distribution: leads to shear flow Rate of Twist Structural cells Skin thickness Stress on longitudinal stringers Idealized “booms” 16

Calculations Longitudinal Stringers - ‘Booms’ Skin, Spars, & Ribs - ‘Webs’ 17

Experimental Research Limited data for most composites at cryogenic temperatures Data that does exist not compiled or inaccurate Most research done on cryogenic storage tanks Use the resins found in this research Materials properties tend increase with decreasing temperature

Experimental Research Aerospace Structures Lab - LN 2 dipped samples

Experimental Research Aerospace Structures Lab - LN 2 dipped samples

Experimentation Tensile Test Ultimate Tensile Strength Flexure Test Isotropic material: UTS Non-Isotropic material: Flexure Strength 21

Experimentation Impact Tests Impact Strength Short Beam Bending Shear stress Length to thickness ratio Shear Modulus, G 22

Difficulties in Experimentation Temperature variance. Difference between ambient and experimental conditions Cooling system Damage to testing devices 23