SAR-Venus Atmospheric Exporer

Venus Atmospheric ExplorerEfrain Ortiz | Christopher Bill | Julius Chua

05/05/2016

SAR Outline❖ Introduction

➢ Objective

➢ Requirements

➢ Mission Profile

❖ System Overview

➢ System Specifications

➢ Mass Statement

❖ Subsystem V&V

➢ Entry and Deployment

➢ Structure

➢ Propulsion

➢ Power

➢ Avionics

❖ Future actions

ObjectiveThe purpose of this project is split into three main objectives:

● Demonstrate the ability to enter target altitude/latitude and

deploy payload.

● Demonstrate feasibility of extended operation of unmanned

system in the Venusian atmosphere.

● Collect data with scientific instruments on the Venusian altitude of

55-65 km.

Customer Requirements

● Entry capsule deploys blimp at target optimal location

● 6 month continuous flight duration

● Cruise altitude of 55-65 km for the mission duration

● Must be solar-powered

● System should carry a 20 kg scientific payload

● Communicate data back to Earth

(1)Entry at 200 km altitude

Ve= 11 km/s

Time of descent- 25 sec

(2)Drogue parachute deploy

Mach 1.5125 km

Front cover release

Terminal Velocity-170 m/s

Duration 17 seconds

(3)Payload separation from aft cover.

105 km

Gondola falling at terminal velocity

(4)Main Parachute Deploys

Mach .8 100 km

Average Descent rate of 82 m/s

Duration 13 min

(5)Partial inflation under main parachuteTime of inflation: 10 minTank Jettison

Operational conditions:Cruise Altitude: 57 kmCruise Latitude: 75°Wind Speed: 40 m/s

(5)

Mission Profile

System Overview➢ System Characteristics

○ Deploys blimp at optimal

destination

○ Cruise altitude: 55 km

○ Cruise latitude: 75o

○ Thrust: 9.17 kN

○ Flexible Solar array efficiency: 12%

○ EoL Power loss: 10% or 8144 Watts

○ EoL Volume Lost: 0.4%

○ Carries 20 kg science payload

Length: 27 m

Diameter:8.2 m

[4] Jenkins, C. H. "Inflatable Solar Arrays." Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications. Vol. 191. Reston, VA: American Institute of Aeronautics and Astronautics, 2001. 464-68. Print.

Basic Mass (kg)

Growth Allowance

Predicted (kg)

Required (SRD)

Margin (Kg)

Propulsion/PWR 26.04 1.302 27.342 35 7.658

Structure 235 11.75 246.75 140 -106.75

Communications 11.8 1.77 13.57 10 -3.57

Entry/Deploy 235 14.1 249.1 300 50.9

Total w/o margin 429.84 25.022 454.862 495 -41.762Margin 35

Total Allocated 429.84 25.022 454.862 530 6.762

System Mass Statement

Heat Shield Verification by similarity:

Venus Huygens Model Actuals

Convective W/cm2 101 46 40-50

Radiative W/cm2 334 185 143

Combined W/cm2 436 231 193

Max Heat Flux (J/cm2)

4033 4634 3500-4000

Thickness (mm) 11.5 13.2 17.4-18.2

Mass (kg) 40.5 21.3 30

Heat Shield Validation

● PKW3-IRS: Plasma Generators ● The select few devices capable of reaching heat fluxes needed● Test Objectives:

○ Total Heat Flux of 4033 J/cm2 ○ Duration of 20 seconds○ Demonstration of material behaviour

[5] Wright, Micheacl J. "POST-FLIGHT AEROTHERMAL ANALYSIS OF HUYGENS PROBE." WPP-263 (n.d.): n. pag. Web.

ParachuteRequirements:

• Drogue shall lower the velocity of the payload and aft from mach 1.5 to a velocity suitable for Disk Band Parachutes.

• Main Parachute shall deploy carrying the gondola and release at operating altitude. • Conditions:

• Drogue: Opening Shock-> 776 N ( 172 lbf )• Main: Opening Shock -> 30,000N ( 6744 lbf)• Gemini Mission: Drogue opening shock -> 143 psf• No main parachute was found with similar characteristics

● Full size testing will be conducted in the National Full-Scale Aerodynamics Complex in Ames. ( Wind Tunnel)

Tank Verification

Burst Testing Result

Pressure (x2) 14e7 pa

Max Stress 2.033e9

Yield Str 1.57e9

Min FOS 0.75

Failed Before 2.0 FOS

Tank Test Result Material Carbon fiber-T1000

MEOPMaximum ExpectedOperating Pressure

Yield Str Max stress

Min FOS

7e7 pa 1.57e9 pa 1.02e9 pa 1.75

Leak Rate Summary

Mission Duration 6 Months

Material Mylar & Kapton

Volume Leak Rate 2.52E-04 m3/hr

BoL Lift 2,352 N

Lift Lost 8.86 N or 2 lbs

% in Volume Lost 0.4%

Leak Rate Verification

[1] "958. Permeation and Outgassing of Vacuum Materials." Vacuum 23.12 (1973): 472. Outgassing and Permeating. Professional Engineering Computations (PEC, Inc), 31 Mar. 2003. Web. Oct.-Nov. 2015.[2] Hogat, J. T. "Investigation of the Feasibility of Developing Low Permeability Polymeric Films." /tardir/mig/a304557.tiff (n.d.): n. pag. The Boeing Company, NASA, Dec. 1971. Web. Oct.-Nov. 2015.

Envelope Verification

• Requirements:• ΔPressure of 7290 N/m2

• Minimum FOS: 1.5• Load bearing material: Dyneema fibers

• Challenges• Meshing

• Assumptions (hoop Stress)• Simulation

• thickness/pressure [ (x1,000), (x10,000) ]

[3] Nicolai, Leland M., and Grant E. Carichner. Fundamentals of Aircraft and Airship Design. Reston, VA: American Inst. of Aeronautics and Astronautics, 2013. Print.

(xC)

(xC)

1,000x 10,000x

SeptumStress Strain

Displacement FS4%Break limit

Break

strain:

4e-2

True SizeSeptum Simulation

PropulsionRequirements

Cruise Speed: 40 m/s

Power Required: 40311 Watts

Thrust Required: 9.17 kN

Test:-Wind tunnel with V

in= 40 m/s

-Air density = 1.225 kg/m

-Propeller RPM = 2700 Target Velocity: 43.31 m/s

CharacteristicsPropeller Efficiency: 80%

Propeller Diameter: 12.55 m

Number of blades: three

Motor power density: 5.92 kW/kg

Motor weight: 6.81 kg

Power

Requirements

EoL Power Required: 40.55 kW

Lifespan Required: 6 months

CharacteristicsMass/Area of solar array: 0.178 kg/m2

Area of solar array: 241.29 m2

Total mass of solar array: 42.95 kg

Power generated: 76.9 kW

Solar cell degradation: 3 %/year

EoL power generated: 68.8 kW

TestingLife cycle test (6 months) in cyclic corrosion chamber at -13°C in sulfuric

acid environment

Testing power output with simulated solar input of 2.61 kW/m2 at 1 month intervals

Maximum power generation loss of 30% after 6 months Image credit: Astroinstruments

Image credit: Vanguard Space Technologies

Future Actions Parachute

● Result: Opening Shock Force exceeded cluster loads of parachutes on market. ○ Action: Decrease the diameter of the main parachute ○ Consequence: Faster decent, meaning shorter time of inflation

○ Alternate Action: Delay drogue deployment ○ Consequence: Drogue will expect higher loads

Future Actions (Enveloped & Tank)Envelope

• Investigate Envelope FOS discrepancy• Simulated: 1.92• Predicted: 3.1

• Need Weight reduction• 28 kg overweight

Action

• True scale simulation• Use other verification methods

Repercussions

• Subsystem Design may change

Helium Tank

• Failed Burst Test• Need thicker tank shell

Action

• Thicken shell wall• Thicken heat shield

Repercussions

• Will be heavier on entry• Less inflation time• Faster orbit entry• Changes on heat shield

References[1] "958. Permeation and Outgassing of Vacuum Materials." Vacuum 23.12 (1973): 472. Outgassing and Permeating.

Professional Engineering Computations (PEC, Inc), 31 Mar. 2003. Web. Oct.-Nov. 2015. <http://lpc1.clpccd.cc.ca.us/lpc/tswain/lect8.pdf>.

[2] Hogat, J. T. "Investigation of the Feasibility of Developing Low Permeability Polymeric Films." /tardir/mig/a304557.tiff (n.d.): n. pag. The Boeing Company, NASA, Dec. 1971. Web. Oct.-Nov. 2015. <http://www.dtic.mil/dtic/tr/fulltext/u2/a304557.pdf>.

[3] Nicolai, Leland M., and Grant E. Carichner. Fundamentals of Aircraft and Airship Design. Reston, VA: American Inst. of Aeronautics and Astronautics, 2013. Print.

[4] Jenkins, C. H. "Inflatable Solar Arrays." Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications. Vol. 191. Reston, VA: American Institute of Aeronautics and Astronautics, 2001. 464-68. Print.

[5] Wright, Michael J. "POST-FLIGHT AEROTHERMAL ANALYSIS OF HUYGENS PROBE." WPP-263 (n.d.): n. pag. Web.