NASA SL Critical Design Review · •Entire assembly can be removed Fin Interface University of Alabama in Huntsville USLI CDR 1/16/2018 18. Fin Can Assembly ... •3D printed in

University of

Alabama in

Huntsville

NASA SL

Critical Design

Review

University of Alabama in Huntsville

USLI CDR11/16/2018

LAUNCH VEHICLE


USLI CDR21/16/2018


USLI CDR31/16/2018

Vehicle Summary

• Launch Vehicle Dimensions– Fairing Diameter: 6 in.– Body Tube Diameter: 4 in.– Mass at lift off: 43.8 lbm. – Length: 103 in.

• Concept– L-Class Solid Commercial Motor– Rover Delivery– Electronic Dual Deployment– Fiberglass Airframe

Vehicle CONOPS

11/3/2017University of Alabama in Huntsville

USLI PDR4

Powered Ascent:

0 – 3.3 seconds

0 – 1,190 ft.

Deploy Drogue:

19 seconds

5,429 ft.

Deploy Main:

62 seconds

600 ft.

Landing:

121 seconds

0 ft. Deploy Rover:

Team Command


USLI CDR51/16/2018

Vehicle Summary

Rover Piston Main

Parachute

Drogue

Parachute

Coupler

12 in.

Tracking/Rover

Deployment

Avionics

Fins (x4)

Recovery

Avionics

Forward

Airframe

30 in.

Aft

Airframe

42 in.

Payload

Fairing

36 in.

CG

56 in.

CP

69 in.

• Upper Airframe houses the rover, piston ejection system, and GPS tracker

Upper AirframeOverview


USLI CDR61/16/2018

• 6 in. elliptical shape; 6.17 in. OD;

• ABS Plastic; 3-D printed in-house

• 1.75 in. shoulder; shear pinned to fairing

• 0.25 in. Aluminum bulkhead

Nose Cone


USLI CDR71/16/2018

• Houses payload and deployment device

• Fiberglass; 6.17 in. OD, 6 in. ID

• Shear pinned to nose cone; 10-32 bolt connection to transition

Fairing


USLI CDR81/14/2018

Transition


USLI CDR9

• Three piece design, two 3D printed ABS plastic, one 0.5 in. thick aluminum bulkhead

• Each piece has holes for threaded inserts• Held together using ¼-20 and 10-32 bolts

Forward Insert Aft

1/16/2018

Transition


USLI CDR10

• Three piece design allows for a 57% reduction in weight

• Max stress on aluminum bulkhead: 0.712 ksi• Yield stress: 42 ksi

1/16/2018

• Connects 4 in. body tube to the 6 in. fairing

• U-bolt for recovery harness attachment point

• Shear pins connect to 4 in. body tube

• Threaded rod with hex nuts for connection to fairing

Transition Coupler


USLI CDR111/16/2018

• CO2 Powered – 12 gram cartridge

• Spring driven spike used to release stored gas

• 60 lbf. test monofilament fishing line used as arming tether for spring

• Hot wire cuts tether to release spring

• Two main components: piston head and CO2

housing

Piston Overview


USLI CDR121/16/2018

• Ejects rover and nose cone

• Fiberglass coupler with aluminum bulkhead

Piston Head


USLI CDR131/16/2018

• Houses CO2 cartridge and release mechanism

• 3D printed ABS Plastic

• Allows for easy and quick modification upon testing results

CO2 Housing


USLI CDR141/16/2018

• CO2 housing positioned in transition shoulder

• Mounted to side using 3-D printed brackets and 4-40 bolts

• Keeps housing fixed during flight

Piston Configuration


USLI CDR151/16/2018

• Aft Subsystem Components

Aft Subsystem Overview


USLI CDR16

Recovery Bulkhead & U-Bolt

Fin(s)Fin Can Thrust Plate

Motor Retention RingMotor/Motor Case

1/16/2018

• Trapezoidal Fin Set (4)

– Maintain stability

• G10 Fiberglass

– Great strength/weight ratio

– 3/16” thickness

• Flutter Speed

– Calculated to be Mach 1.947 (2191.57 ft./sec)

Fins


USLI CDR171/16/2018

• 4 bolts perpendicular to fin face

• 6 bolts normal to body tube to hold shape

– Also used to hold fin can in vehicle

• Entire assembly can

be removed

Fin Interface


USLI CDR181/16/2018

Fin Can Assembly Overview

• Consists of: Fin Can, Motor Retention Ring, Thrust Plate, and Rail Button Press fit nut


USLI CDR191/16/2018

Exploded View of the Fin Can Assembly


USLI CDR201/16/2018

Fin Can

• 3D Printed in house

• Material: ABS plastic

• Purpose: Fin retention and centering of the motor

• Attached to the body tube using 4-40 bolts which maintain the shape of the Body tube


USLI CDR211/16/2018

Fin Can Dimensions


USLI CDR221/16/2018

Thrust Plate

• Machined in house

• Material: 6061 Aluminum

• Purpose: Transfer motor thrust to the airframe

• Attached to the fin can using the motor retention bolts

• Part was added due to concern of shearing the Fin Can while duringmotor burn


USLI CDR231/16/2018

Thrust Plate Dimensions


USLI CDR241/16/2018

Motor Retention Ring

• 3D printed in house

• Material: ABS plastic

• Purpose: Motor retention

• Attached to the fin can using the motor retention bolts

• Aft retention was chosen due to the difficulty of disassembling the forward retention system


USLI CDR251/16/2018

Motor Retention Ring Dimensions


USLI CDR261/16/2018

• Aerotech L1420R-PS

– Best met altitude target

• Avg. Thrust: 326.18 lbf.

• Burn Time: 3.2 sec

Motor Selection

27

Motor Altitude

Aerotech L2200 6107 ft.




USLI CDR

• Dimensions

– Total length – 103 in.

– Wet mass – 43.80 lbm.

– CP location – 68.93 in.

– CG location – 55.60 in.

OpenRocket Flight Simulation

28

55.60 inches

68.93 inches


USLI CDR

Stability Margin

29

Motor Burnout (3.28 cal.)

Initial Stability (2.22 cal.)

Apogee


USLI CDR

OpenRocketFlight Simulation


USLI PDR30

Attribute Value

Apogee (ft.) 5429

Length (in.) 103

Max. Mach Number 0.60

Rail Exit Velocity (ft./s) 60.6

Static Stability (cal.) 2.22

Motor Designation AT L1420R – P

Thrust-to-Weight Ratio 8.7

CG 56 in.

CP 69 in.

OpenRocket Flight Simulation

31

Motor Burnout (3.27 sec.)

Apogee (18.62 sec.)

Main Deploy (62.39 sec.)


USLI CDR

• 1-D method used to verify OpenRocket sim

– Goal: Determine uncertainty in projected altitude

– Randomly varies conditions by a percentage

▪ drag coeff., vehicle mass, propellant mass, case mass

▪ Varied between ±6.25% and ±2.5%

– Use drag coefficient from subscale flight

▪ 𝐶𝑑 = 0.56

– 10,000 flights per simulation

Full Scale Monte Carlo Simulation


USLI CDR

Full Scale Monte Carlo Simulation

33

Mean: 5626.31 feet

Median: 5617.45 feet

Std. Deviation: 192.29 feet

Max Altitude: 6463.91 feet

Min. Altitude: 5010.83 feet


USLI CDR

• Central Subsystem responsibilities:

– Coupler between airframes

– Flight Avionics

– Ejection System

– Tracking and Ground Station

– Recovery System

Central Subsystem Overview


USLI CDR

https://www.apogeerockets.com/Building_Supplies/Parachutes_Recovery_Equipment/Parachutes/High_Power/84in_Iris_Ultra_Parachute?zenid=a1aiv1itb71rpsg0g4pb66elc2

Drift Analysis

Vwind

35

• Monte Carlo Drift Model

– Assumes:

• Apogee is directly above the launch rail

• The parachute does not open immediately

• The drift distance stops once a component lands

• Horizontal acceleration is solely based on relative velocity

• Drogue parachute is negligible once the main is fully deployed

Vrelative

Wind Speed (mph) 0 5 10 15 20

OpenRocket Drift

Distance (ft)17.6 465.8 946.7 1461.9 1995.7

CRW Model Drift

Distance (ft)0 573.19 1148.9 1741.9 2311.8


USLI CDR

• Requirement: No individual section will have a kinetic energy greater than 75 ft.-lbf. upon landing

• Terminal velocity under drogue: 112.7 ft./sec.

• Terminal velocity under main: 17.45 ft./sec.

Recovery System Calculations

36

Vehicle

Section

Mass (lbm.) KE (ft.-lbf.)

Fairing 14.35 67.85

Coupler 11.15 52.72

Aft 9.89 46.76


USLI CDR

• Drogue Parachute Deployment:– Deployment at apogee– Fruity Chute CFC-18 (Cd = 1.5)– Shock Cords: 1 inch Nylon (50 ft)– Connected between forward motor

retention bulkhead in lower airframe and avionics bay housing.

– Descent speed under drogue: 112.7 ft/s

• Main Parachute Deployment:– Deployment at 600 ft above ground

level– Fruity Chute 96” Iris Ultra (Cd = 2.2)– Shock Cords: 1 inch Nylon (50 ft)– Connected between fairing

bulkhead and avionics bay housing. – Descent speed under main: 17.45

ft/s

Recovery System


USLI CDR

https://fruitychutes.com/buyachute/l3-elliptical-72-to-120-c-8/120-custom-parachute-50lb-20fps-p-6.html

https://www.apogeerockets.com/Building_Supplies/Parachutes_Recovery_Equipment/Parachutes/High_Power/84in_Iris_Ultra_Parachute?zenid=a1aiv1itb71rpsg0g4pb66elc2

Recovery Avionics Subsystem

• 2 PerfectFlite StratoLoggerCF altimeters; each with an independent 9V battery and pull pin + SPDT momentary activation switch

• 4 Safe Touch terminals, e-matches, and black powder charges

• Full redundancy in avionics and ignition

Avionics


USLI CDR

Coupler


USLI CDR

Charge Well

U-Bolt

Screw Terminal Strip

Flight Computer

Batteries

RBF Switches

12 in.

Recovery Deployment Avionics

40

• Normally Closed SPDT Pull Pin Microswitch– Prevents ignition during assembly– Helps preserve battery life

• Primary Drogue charge fired at apogee– Secondary fired one second after

• Primary Main charge fired at 600 ft.– Secondary fired at 550 ft.

• Primary charges contain 4 g. of black powder

• Secondary charges are 2 g. larger than primary


USLI CDR

GPS Tracking & Rover Deployment Subsystem

41

System• CRW will use a custom PCB that contains an Xbee Pro-PRO

900HP RF module, Teensy LC, and MTK3339 GPS Chip

• Xbee transmits GPS coordinates to a receiver connected to the ground station laptop

• GPS sentences are parsed and written to file for flight data

• Rover Deployment Electronics operated via XBee

Structure Integration• 3D printed mount to secure tracker and deployment

electronics PCB within transition section of the rocket

• Three axis security and battery retention to ensure components are kept intact


USLI CDR

Subscale Design

42

Scaling Factors:• Geometry of the design• Average Thrust of Motor and Thrust Curve• Kinetic Energy


USLI CDR

• Successful recovery of all three subscale flights

• Altimeters ignited the black powder charges at the correct altitudes

Subscale FlightResults


USLI CDR

• Flight 1- Apogee 2884 ft., some weathercocking

• Flight 2- Apogee 2323 ft., severe coning

• Flight 3- Apogee 3165 ft., vertical flight

Subscale FlightResults


USLI CDR

• Using data gathered from the altimeters, the drag force and coefficient for the vehicle were found

• Using a weight of 6.33 lbs, an acceleration of 60.128 ft/s, an A of 0.0533 ft2, a 𝜌of 0.0751 lb/ft3, and a velocity of 396.55 ft/s:

– Cd = 0.56

SubscaleDrag Coefficient


USLI CDR

▪ A = Area of the exposed section, ft2

▪ 𝜌 = density of the air, lbm/ft3

▪ Cd = Coefficient of Drag▪ u = Velocity, ft/s▪ m = mass, lbm▪ A = acceleration of the vehicle, ft/s2

▪ g = acceleration of gravity, ft/s2

• Diameter: Deployed 16.2 in., Integrated 5.7 in.

• Rover Length: 14.6 in., Chassis Length: 12 in.

Payload


USLI CDR

• Rover fits inside the piston, which ejects it from the fairing

• CO2 cannister pushes rover through nose cone

Payload Integration


USLI CDR

1. The rover is ejected from the rocket

2. Wheels deploy and rover moves 10 ft.

3. Rover stops and deploys solar panels

Payload CONOPS


USLI CDR

1

3

2

• Stores and protects tray of rover electronics

• 12 in. x 4 in. x 3 in., Aluminum 6061-T6

• Machined from single Aluminum block

• Connects to motors, electronics tray, and solar panel lid

Chassis


USLI CDR

• Spokes pulled by springs to expand wheel

• Wheel hub and spokes CNC milled aluminum

• Integrated Diameter: 5.7 in.

• Deployed Diameter: 16.2 in.

• Spoke 6 in. x 0.5 in. x 0.25 in.

Wheel


USLI CDR

• Used to keep chassis upright during deployment

• 3D printed ABS

• 11 in. x 0.25 in. x 0.5 in.

• Mounts to chassis using a hinge

• Torsion spring pushes out after deployment

Stabilizing Arm


USLI CDR

• This table details the normal load cases for each structural component

• The wheel hub is the weakest component but can withstand a 73% load increase

Strength Check Notes

52

Part Load Case Safety Margin

Chassis 210 lbf (sidewall) +2.45

Chassis 210 lbf (base) +1.37

Wheel Hub 210 lbf (sidewall) +0.73

Wheel Hinge 105 lbf (each) +5.11

Spoke 210 lbf (lengthwise force) +11.98

Spoke 7 lbf (Drive force) +6.42


USLI CDR

• Rover electronics contained inside chassis

• Tray designed to wire and organize electronics outside chassis

• Tray lowered into top of chassis once assembled

Electronics Tray


USLI CDR

• Designed to avoid interference with motors

• Tray Assembly: 11.6 in. x 3.8 in. x 2 in.

Electronics Tray


USLI CDR

• Lid is closed during rover travel for protection

• Gear slides top lid out to reveal solar panel in chassis

• 3D printed ABS lid, gear bought from McMaster-Carr

• 12 in. x 4 in. x 0.375 in. when closed

• 12 in. x 7.25 in. x 0.5 in. when open

Rover Lid with Mechanism


USLI CDR

• The mass of all components totaled 6.6 lbm.

• A 6% margin was added to the total weight to account for fasteners and adhesives

Rover Mass Budget

56

Component Mass (lbm.)

Chassis 2.0

Wheel Assembly 2.4

Lid/Solar Deployment 0.7

Tail 0.2

Electronics 1.3

6% Margin 0.4

Total 7.0


USLI CDR

Payload Power Budget


USLI CDR

Part Name Current

(mA)

Voltage (V) Adj Current Duty Cycle

(%)

Time (hr) Total (mWh)

Arduino Mega 0.17 5 0.0787 100 2.5 0.984

Camera 350 5 162.037 10 2.5 202.546

GPS 53 3.3 16.194 20 2.5 26.721

IMU 0.35 3 0.0972 100 2.5 0.729

Pressure/Temp 0.36 3.3 0.11 17 2.5 0.154

Wheel Motors 650 12 722.222 20 2.5 4333.333

Lid Motors 360 5 166.667 5 2.5 104.167

Radio transmit 229 3.3 69.972 10 2.5 57.727

Radio idle 44 3.3 13.444 90 2.5 99.825

Datalogger 100 3 27.778 10 2.5 20.833

Power

required

4847.01

Part Name Current

(mA)

Voltage (V) Adj Current Duty Cycle

(%)

Time (hr) Total (mWh)

Li-Ion Battery 2600 10.8 N/A 100 1 28080

Power

Supplied

28080

Power

Supplied

28080 mHr Power

required

28080 mHr Factor of

Safety

5.793 mHr

Electronics Block Diagram


USLI CDR

Electronics Failure Path

59

• Emphasizes dependence of each lower level component on the component above it


USLI CDR

SAFETY


USLI CDR

• Training and communication are key to maintain safety and avoid mishaps

• Priorities in CRW safety program (in order of importance):1. Safety to personnel2. Safety to facilities & permanent systems3. Safety to flight hardware & objective success

• Established SOP and regulations to maintain safety practices

• Team is transitioning from designing to manufacturing and testing

Safety Overview


USLI CDR

• CRW team meets twice weekly

• Safety briefings are held to update the team with pertinent information

• All conducted tests have documentation of results and lessons learned

• Documents and test results are recorded to the team’s server for ease of access

Communication


USLI CDR

• Philosophy– Standardization of processes– Address risks and hazards with proper method

• Creation– Based on previous versions– In collaboration with team leads to adapt SOP steps to the features and

mission needs of the Vehicle and Payload

• Approval– Reviewed and approved by Red team members and faculty advisor

• Implementation:– Use latest version– Safety Monitor to ensure strict adherence to steps and safety aspects

Standard Operating Procedures


USLI CDR

Launch and Assembly Procedures

• Final rocket assembly procedures for the Full Scale have been developed to fit the design concept

• Minimum assembly or modification of airframe at field

• Field operations are limited to subsystem integration and loading of energetics

• Simulated runs of launch procedures will take place at least one week prior to any launch


USLI CDR

• Factors affecting launch vehicle and payload

– Sudden high winds

– Humidity

– Extreme temperatures

– Terrain

• Mitigations established:

– Minimum exposure to environment

– Constant monitor of the weather

Environmental Factors


USLI CDR

• Factors affecting the Environment and Local communities– Hot exhaust

– Landing in trees, difficult terrains

– Landing on infrastructure and private properties

– Waste from manufacturing and launches

• Mitigations Established:– Inspection and understanding of launch field

– Waste collection and proper disposal

– Constant monitor of wind conditions

Environmental Factors


USLI CDR

Training Activity Date

Red Cross First Aid CPR/AED/FA Completed

Basic Emergency Procedures Completed

Process Hazard Analysis Completed

Safe Testing Procedures Completed

Root-Cause Analysis Completed

Outreach Safety Procedures Completed

Sub-scale Launch Safety Procedures Completed

Hazardous Material Handling/Disposal Completed

Fire Extinguisher training Completed

Workshop Safety Briefings 1/23/2018

System Ground Tests Briefings 1/30/2018

TBD TBD

Upcoming Trainings

67

Safety Briefings are held based to relevant safety topics.


USLI CDR

• Test Plan changes since PDR

– Completed tests includes the subscale launch and subscale charge test.

– New tests planned for Rover and Launch Vehicle fairing systems.

– GPS test is on going to ensure constant compatibility.

Test Plan


USLI CDR

Test Plan

69

Test Number Test Type Test Status

T1 Subscale Ejection Charge Test ➢ Test has been conducted prior

to the subscale flight on 11-19-

2017

➢ Test shows that rocket has to

go drogue-less and use only

one shear pin on both main and

drogue for successful recovery.

T2 Subscale Flight ➢ Successful launch and recovery

➢ Vehicle did not reach initial

altitude prediction

T3 GPS tracker range and

capability/Telemetry

➢ Tracker currently Exhibit poor

performances.

➢ Team is currently learning how

to trouble shoot issues with

tracker.

➢ Telemetry test is planned for

Feb 10-11

T4 Fin Can Load Test ➢ Test will be planned for the end

of January to the early February

before the full scale launch.


USLI CDR

T5 Rover Piston Deployment test ➢ Test will be scheduled in

February when the piston is

manufactured.

T6 Fairing Vibration Test ➢ Test is planned for middle to end

of February once test articles

arrive

T7 Faring Drop Test ➢ Test is planned for middle to end

of February once test articles

arrive

T8 Fairing Transition Compression test ➢ Test will be conducted once FEA

results shows doubts in the

structures.

T9 Rover Operational Test ➢ Test will be planned and carried

out when rover is constructed.

T10 Full Scale Charge Test ➢ Test will be conducted

approximately one week before

the first full scale launch date

T11 Full Scale Flight ➢ Flight will be held on Feb 17 and

18

Test Plan


USLI CDR

TESTING AND REQUIREMENTS VERIFICATION


USLI CDR

• Document template for tracking requirements verification

• Allows for all 4 methods to be tracked

• Place to record test procedures, personnel, and results

• Template is in Critical Design Review Appendix

Verification Reports


USLI CDR

• Expected/In-Progress Verification Reports

– Review of project plan and procedures

– Review of all submitted documents, website, and teleconference setup

– Review of Educational Outreach Reports

– Demonstration of reusability through full-scale flight

General Requirements Verification


USLI CDR

Test

Number

Test Type Description Test Status

T1 GPS tracker

range and

capability

o The GPS tracker of the launch vehicle and the

payload will be tested inside of their respective

fairing/compartment. This is to ensure that the GPS

can reliable transmit and receive signals.

o The test will also be conducted in obstacles such as

trees and buildings to reveal the limits of the GPS.

o The full test of GPS system performance and

reliability will be the subscale launch

o Single component tests (radio, GPS receiver), can

be done by a team member without supervision.

o Subscale launch tests will adhere to SOP.

➢ Tracker currently

Exhibit poor

performances.

➢ Team is currently

learning how to

trouble shoot

issues with tracker.

T2 Electrical Charge

on E-matches

o Spectrum analysis will be conducted to determine if

transmission waves will enter into the avionics

coupler and affect the electronic components

o The tracker can be placed inside the coupler to

determine how much transmission power exits. The

idea is if excessive power exits the coupler, an

excessive amount can enter.

o Shielding can then be implemented based on the

results.

o This test will require more than one team member.

However, Red team members and the mentor will

not be required for this type of test.

➢ Test is has not

been planned.

Test Plan


USLI CDR

T3 Altimeter Test o The functionality of the altimeter will be evaluated with

the Charger Rocket Works’ altimeter testing container.

o Only applied for in-house made altimeters. Third party

altimeters like Statologger will not require testing.

➢ Test will be scheduled

when altimeter has

been created.

T4 Ejection Charge Test o This is to experimentally verify the correct

amount of black powder to be used in the

ejection of the drogue and main parachutes.

o An SOP has to be developed for this test

o This test is dangerous and only Red Team

with the presence of the mentor can conduct

the test.

➢ Test has been

conducted prior to the

subscale flight on 11-

19-2017

➢ Test shows that rocket

has to go drogue-less

and use only one shear

pin on both main and

drogue for successful

recovery.

T5 Rover Piston Deployment test o Experimentally verify the functionality of the

rover deployment mechanism.

o The test requires no pyrotechnics so anyone

in CRW can conduct the test.

➢ Test will be scheduled

in February when the

piston is manufactured.

T6 Fairing Transition Compression test o Experimentally verify the compression strength of the

fairing transition

o Only the section in doubt from the FEA results shall

printed for test.

o Currently planned to be a destructive test

➢ Test will be conducted

once FEA results

shows doubts in the

structures.

T7 Rover Terrain Test o The Rover, once constructed, shall be put through its

paces in different terrain conditions (except water and

mud).

o Test is to verify the spoke wheel design.

➢ Test will be planned

and carried out when

rover is constructed.

Test Plan


USLI CDR

Full Scale Budget

Budget

Summary

Airframe $ 1763.11

Electronics $ 334.89

Recovery $ 899.09

Motors $ 1589.96

Rover Structure $ 438.97

Rover Electronics $ 682.34

Total Cost $ 5708.36


USLI CDR

On the Pad Budget

Launch Vehicle

Airframe $ 997.81

Electronics $ 167.45

Recovery $ 621.09

Motor $ 259.99

Rover $ 621.00

Total $ 2046.34


USLI CDR


USLI PDR78