The document outlines a proposed Venus Atmospheric Explorer mission to deploy a solar-powered blimp at 55-65 km in the Venusian atmosphere for 6 months. It describes the objectives to demonstrate entry and deployment capabilities and collect scientific data. Key requirements include a 20 kg payload and continuous solar-powered flight for 6 months. The system overview specifies characteristics of the blimp including a 27 m length and 8.2 m diameter. Subsystems including the heat shield, parachutes, propulsion and power are analyzed, and future work is identified to address issues with the parachutes, envelope design, and helium tank failure.

1. Venus Atmospheric Explorer
Efrain Ortiz | Christopher Bill | Julius Chua
05/05/2016

2. 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

3. Objective
The 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.

4. 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

5. (1)
Entry at 200 km altitude
Ve= 11 km/s
Time of descent- 25 sec
(2)
Drogue parachute deploy
Mach 1.5
125 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 parachute
Time of inflation: 10 min
Tank Jettison
Operational conditions:
Cruise Altitude: 57 km
Cruise Latitude: 75°
Wind Speed: 40 m/s
(5)
Mission
Profile

6. 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.

7. 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 -41.762
Margin 35
Total Allocated 429.84 25.022 454.862 530 6.762
System Mass Statement

8. Heat ShieldVerification 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

9. 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.

10. 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)

11. 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
MEOP
Maximum Expected
Operating Pressure
Yield Str Max
stress
Min FOS
7e7 pa 1.57e9 pa 1.02e9 pa 1.75

12. 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.

13. 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)

15. 1,000x 10,000x

16. Septum
Stress Strain
Displacement FS4%
Break
limit
Break
strain:
4e-2
True SizeSeptum Simulation

17. PropulsionRequirements
Cruise Speed: 40 m/s
Power Required: 40311 Watts
Thrust Required: 9.17 kN
Test:
-Wind tunnel with Vin
= 40 m/s
-Air density = 1.225 kg/m
-Propeller RPM = 2700 Target Velocity:
43.31 m/s
Characteristics
Propeller Efficiency: 80%
Propeller Diameter: 12.55 m
Number of blades: three
Motor power density: 5.92 kW/kg
Motor weight: 6.81 kg

18. Power
Requirements
EoL Power Required: 40.55 kW
Lifespan Required: 6 months
Characteristics
Mass/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
Testing
Life 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

19. 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

20. 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

21. 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.