1. Critical Design Review NASA SL 2016-2017
Iowa State University
Critical Design Review
NASA SL
College of Engineering

2. Agenda Project Overview Design Overview Subscale Safety Project Plan
Budget
Closing

3. College of Engineering
Iowa State University
Project Overview
College of Engineering

4. Team Structure

5. Mission Overview Requirements: Reach an apogee of exactly 5,280 ft
Safely recover rocket and land within 2,500 ft of the launch pad
Fully reusable for another launch on the same day
Perform one onboard experiment
Roll control system
Vehicle requirements (launch rail velocity, stability margin, etc.)

6. College of Engineering
Iowa State University
Rocket Design
College of Engineering

7. Rocket Overview Rocket Specifications: Rocket Features:
• Length – 132 in.
• Body Diameter – 6 in.
• Weight – 49 lb
Rocket Features:
• Carbon fiber air brakes
• Split fin design
• Three-parachute recovery system
• Onboard flight data processing and recording
• Carbon fiber roll induction fins

8. Rocket Sectional Diagram
OpenRocket Diagram:
Nose Cone
Parachute Bay 2 (120” Main and 24” Pilot)
Parachute Bay 1 (18” Drogue)
Motor Mount
Camera Bay
Avionics Bay
Flight Computer Bay

9. OpenRocket Design Stability:
Center of gravity: 89.3 in (from nose cone)
Center of pressure: in (from nose cone)
Stability margin: 2.55

10. Performance Parameters/Motor Choice
Motor selection: Cesaroni 5015L1115-P Classic
Max/avg thrust: 385/251 lbf
Total impulse: lbf-s
Thrust/weight: 7.86 (max)/5.12 (avg)
OpenRocket Simulation Results:
Max acceleration: 219 ft/s2 (6.80 g)
Max velocity: 587 ft/s (Mach 0.53)
Apogee: 5,481 ft
Launch rail exit speed: 54.2 ft/s
86” launch rail travel on a 12’ launch rail
Cesaroni L1115 (el-eleven-fifteen) - this is a change from our previous reports, said change will be covered more in depth later in the presentation
At lift off, a 7.86 Maximum thrust/weight ratio will be present
5.12 is average thrust/weight ratio. this reflects a standard 5:1 thrust/weight ratio for most rockets
Openrocket Simulation Results
This simulation results reflect the performance of the el-eleven-fifteen. Here, we have a max acceleration of 219 ft/s squared, and a max velocity of 587 ft/s. The projected apogee during this simulation is 5,481 feet, above our target apogee. Finally, we have a launch rail exit speed of 54.2 ft/s

11. Rocket Design Materials
6” Bluetube airframe with couplers
Five ½” birch plywood bulkheads
Fiberglass nose cone and main fins
Carbon fiber air brakes
Carbon fiber roll control fins
3D printed exterior fins
Aero-Epoxy
-Blue tube airframe with couplers: 6” diameter chosen to account for the camera system and electronics, it is also an incredibly durable material
-Five, ¼” birch plywood bulkheads -- meant to support the axial loads from the motor, also act as component housing with various bays in the rocket
-Fiberglass nose cone and fins
-Carbon fiber air brakes and roll control fins- carbon fiber is a light-weight, tough material
-3D printed exterior fins - 3d printing allows for easy customization
-Aero-Epoxy for strong adhering abilities, also forms a ½” fillet radius between components within our rocket

12. Nose Cone Design Nosecone – 5:1 Ogive 5:1 vs. 4:1
Filament wound fiberglass
Aluminum tip
30” long
5:1 vs. 4:1
Shifts CG forward
RCS fins behind CG
filament wound fiberglass
Roll control system is aft of the center of gravity

13. Motor Mount Subsystem Hardware: 75 mm Blue Tube motor tube
Aeropack flanged retainer
Load transfer through after compression
5 ½” Centering ring assemblies

14. Main Fin Design Main Fin Design: Split fins 4 sets of fins (8 total)
Material
G10 fiberglass
Light
Durable
Geometry optimization for fin flutter
45 different fin designs tested
increase drag, reduce stability, higher stability margin

15. Main Fin Design Front Main Fin Dimensions: Back Fin Dimensions:
Fin flutter velocity: ft/s
FoS = 1.54
Divergence Velocity: ft/s
Fin flutter velocity: ft/s
FoS = 1.78
Divergence Velocity: ft/s

16. Camera Bay 5 radially oriented Mobius cameras 360 degree field of view
2 downward facing cameras
airbrake/roll control confirmation
BRB900 GPS Transmitter
filament wound fiberglass
Roll control system is aft of the center of gravity

17. Camera Bay GPS Transmitter BRB900 900 MHz spread spectrum transmitter
Transmits at 250 mW
Easily integrated in Camera Bay
Can store 2.5 hours of data at 1 Hz
filament wound fiberglass
Roll control system is aft of the center of gravity

18. CFD Simulations Pressure 20.23 lbs (~90 N) Worst case scenario
For four air brakes
80.92 lbs (360 N)
Maximum torque of the servo
Velocity
Maximum velocity for testing
580 ft/s (176.8 m/s)

19. Air Brake Subsystem Air Brake Functions:
The air brakes are actuated by a servo controlled by the flight computer
The flight computer will continuously perform apogee calculations to see if brakes are needed
If the expected apogee is greater than 5,280 ft, the computer will rotate the servo which will pull on cables connected to the air brakes
This process is repeated until apogee is reached

20. Feedback Control Loop

21. Simulated Air Brake Deployment
Air Brake Subsystem
Simulated Air Brake Deployment

22. Air Brake Subsystem Apogee Prediction: Design: Nucleo STM-32
Inertial measurement unit (IMU)
Kalman filtering
Design:
High torque/speed servo (611 oz*in)
Simple cable/pulley system to extend air brakes
Nucleo STM-32 (Flight Computer), Inertial Measurement Unit (accelerometer), [uses kalman filtering to eliminate background noise]

23. Rocket Changes Since PDR
Motor Change: L1350 to an L1115
As a result of adding weight up from 41 lbs to 49 lbs
128” to 132”
Parachute bays needed to be longer
Camera location moved back
GPS transmitter included

24. College of Engineering
Iowa State University
Avionics Overview
College of Engineering

25. Roll Control System Roll Control Requirements:
Read roll rate at motor burnout
Rocket must initiate a roll after motor burnout
Must complete at least two rotations
Counter rolling motion to return to roll rate of motor burnout
Halt the roll for the rest of the flight
Have the ability to be fully removed from the launch vehicle

26. Roll Control System
Two secondary fins, controlled by a single servo, induce and control roll during ascent
6-Degree of Freedom IMU
IMU reads rotational velocity
Generates data for flight computer
Flight computer
Flight computer (Nucleo STM32) controls servo
Servo activates to induce roll
Flight computer will be simultaneously controlling air brakes

27. Roll Control System Roll Control Function:
Flight computer and servo control RCS fins
Barometric pressure sensor and 6-DOF IMU inside flight computer bay
Neutral start position
RCS fins will actuate to a calculated deflection angle after motor burnout
After two rotations, the computer will switch to active roll control and adjust the fin deflection to stop roll
Safeguards in place to ensure no RCS deflection occurs when airbrakes are deployed
Roll Control Function:
Barometric pressure sensor and a 6-DOF IMU will be located inside the flight computer bay with the flight computer and servo controlling the RCS fins
Fins will start in the neutral position during launch (0o deflection)
After motor burnout, the RCS fins will actuate to a calculated deflection angle—inducing a roll in the rocket
Once two rotations have been completed, the computer will switch to active roll control and actively adjust fin deflection to prevent roll
Safeguards will be put in place to ensure no RCS deflection occurs when airbrakes are deployed

28. Roll Control System Roll Control Fin Design: Approximately ⅛” thick
Carbon fiber
Aspect Ratio = 1
Reason behind carbon fiber:
Light, durable, easy to fabricate

29. Avionics Bay Avionics Bay:
Deploy parachutes at proper time and sequence
Two redundant altimeters of different brands to reduce brand specific errors
One “official” altimeter to record flight apogee for competition

30. Avionics Bay Altimeters Entacore AIM 3 rocket altimeter
PerfectFlite StratoLogger CF
Capable of multiple events
Powered by 9V batteries
Securely attached to the avionics bay sled with screws

31. Flight Computer Bay Nucleo STM 32 Barometric pressure sensor
Inertial measurement unit
Runs airbrake Kalman filtering program
The Nucleo is the brains of the flight computer bay
Nucleo takes data from the barometric pressure sensor and acceleration and angular acceleration from its internal measurment unit.
This data then goes through a common filtering program that works with the code running the airbrakes and roll control system.

32. College of Engineering
Iowa State University
Recovery
College of Engineering

33. Recovery Subsystem Recovery Hardware: ⅜” U bolts
⅜” Quick links / ¼” quick links
½” nylon shock cord
Kevlar shock cord protector
Kevlar chute protectors
Anti-zipper ball
Slider release ring
Deployment bag

34. Mission Profile

35. Configuration 1 - Drogue Configuration 2 - Main and Drogue
Recovery Subsystem
Configuration 1 - Drogue
Rocket Weight (on descent)
43 lb.
Parachute Size
18 in.
Descent Rate
119 ft/s
Configuration 2 - Main and Drogue
120 in and 24 in.
14 ft/s
Configuration 1 (Drogue):
Descent rate: 119 ft/s
Parachute: 18” elliptical
Shock cord: 33 ft nylon
Configuration 2 (Main):
Descent rate: 14 ft/s
Parachute: 24” elliptical and 120” elliptical
Shock cord: 27 ft nylon
Forward Section
Avionics Section
Motor Mount
Section Weight
8.0 lb.
9.0 lb.
18.5 lb.
Impact Energy
32.6 ft-lb
36.7 ft-lb
70 ft-lb

36. Calculated Drift from Launchpad
Drift Measurements
Drift Calculations:
Hand calculations - worst case scenario:
Calculated Drift from Launchpad
No Wind
5-mph
10-mph
15-mph
20-mph
Drift Distance
1175 ft
1475 ft
1708 ft
1863 ft
1915 ft

37. College of Engineering
Iowa State University
Subscale
College of Engineering

38. Subscale Design Subscale: Test aerodynamic properties of design
1:3 scale with full scale rocket
Replicate placement of CG and CP
Our open rocket model which is one third the main rocket

39. Subscale Launches Subscale Launches: November 12th, 2016
Boone County, IA
Cesaroni G88 motor
Max impulse: 84 N-s
Max thrust: N
Two Launches:
Ejected altimeter on first launch
Failed separation on second launch
Subscale Analysis:
Remedy altimeter ejection
Failure cause of second launch
Friction too great for motor ejection
Parachute packed too tightly
increase drag, reduce stability, higher stability margin
Sub scale analysis
We had two launches

40. College of Engineering
Iowa State University
Safety
College of Engineering

41. Safety Plan Safety Plan: Written Safety Plan:
Risk management and mitigation
Safety documents
Material safety data sheets
Team Safety Contract
Regulatory and legal compliance
Student Briefing Plan:
Personal protective equipment
Lab safety
Advanced machinery training
Launch Checklists:
Rocket
Avionics
Launch procedures

42. Safety Plan Risk Management and Mitigation: Risk Matrix Rockets
Avionics
Laboratory Safety
Environmental Safety
Probability
Catastrophic- 4
Critical- 3
Marginal- 2
Negligible- 1
Frequent- 5
High
Low
Probable- 4
Moderate
Occasional- 3
Minimal
Remote- 2
Improbable- 1

43. Safety Plan Risk Management and Mitigation: Risks posed by rocket
Failure/ Hazard
Cause(s)
Result(s)
Risk Level
Mitigation
Air Brake Failure
1. Cable fails
2. Wire falls off the pulley
1,2. a. Air brakes stay closed
1,2. b. Do not reach target apogee
1,2. c. The apogee will be significantly different from the target
Moderate
Do many preliminary tests of the air brakes.
Check functionality of air brakes before each launch.
Ejection Charge
1. Ejection charges are
handled inappropriately.
1. a. Damage to the rocket
1. b. Injury to personnel with close
proximity
Dual charges lowers severity if igniter fails
Black Powder charge tests prior to test launch
Handle charges with care

44. Safety Plan Risk Management and Mitigation: Risks posed by rocket
Failure/ Hazard
Cause(s)
Result(s)
Risk Level
Mitigation
Parachute Recovery System Failure
1. Parachute is improperly
packed
2. Parachute lines are
tangled
3. Separates from the
rocket
4. Rocket descends too
quickly
5. Rocket descends too
slowly
6. Parachute has a tear
1,2,3 a. Parachute will not deploy
1,2,3 b. Parachute will not slow descent
1,2,3 c. Parachute will take to long to descend
4. a. Could cause damage to the rocket
5. a. Could cause the rocket to drift to far
6. a. Parachute will not slow descent
6. b. Could cause damage to the rocket
Moderate
to Severe
Parachutes will be packed very carefully and checked by multiple members.
Calculations will be made to determine the descent rate.

45. Safety Plan Launch Operations: Rocket Checklist—Check:
General assembly
Parachutes and recovery systems
Motor assembly
Avionics Checklist—Check:
Wiring
Batteries are secure
Electronics are operational
Launch Procedure Checklist:
Complete rocket and avionics checklists
Position correctly on launch rail
Insert igniter
Handoff to range safety officer

46. Safety Plan Testing: Rocket: Axial load test of Blue Tube
Compressive load test on motor mount
Tensile test of parachute attachment points
Test of event charge
Test of drag separation
Avionics:
Test of power consumption/battery capacity
Compressive test of air brake
Wind tunnel test of air brake
Test of roll induction system

47. College of Engineering
Iowa State University
Project Plan
College of Engineering

48. Remaining Timeline ID Task Due Date 1
Fullscale Tensile/Eject Testing Completed
2/16/17 2
First Full Scale Test Launch
2/25/17 3
Second Full Scale Test Launch
3/4/17 4
FRR Report/ Presentation
3/6/17 5
LRR
4/5/17 6
Launch Days
4/8-9/17

49. College of Engineering
Iowa State University
Budget
College of Engineering

50. Budget
Rocket
$5,400
Avionics
$770
Travel
$3,500
Total
$9,670

51. Iowa State University
Questions?