Transcript Slide 1

Notre Dame Rocketry Team
Preliminary Design Review
November 12, 2014
1:30 PM CT
Mission Objectives
• Launch rocket to precisely 3,000 feet AGL
– Success: +/-50 feet
•
•
•
•
•
Autonomously load payload into rocket
Erect rocket to 5 degrees off-vertical
Autonomously install igniter
Eject payload at 1,000 feet AGL
Successful recovery
Vehicle System: Overview
Downward
facing camera
Section
Label Composed of
Nose Cone/ 1st Drogue Parachute Bay
A
Hollow nose cone of 13 inch length
Payload Bay
B
20 inch carbon fiber body tube & 12 inch phenolic coupler
2nd Drogue Parachute Bay
C
28 inch phenolic body tube (shared with the avionics bay and the main parachute bay)
CRAM (Compact Removable Avionics Module)
D
3D printed cylindrical module; has the diameter of a coupler.
Main Parachute Bay
E
28 inch phenolic body tube (same as section C)
Altitude Controller
F
15 inch phenolic coupler and 6 inch carbon fiber body tube
Fin Can
G
27 inch body tube
Vehicle System - Dimensions
Length of Rocket (in)
Diameter of Rocket (in)
Number of Fins
Fin Span (in)
Weight with Motor (oz)
Weight without Motor (oz)
Estimated Stability Margin with
Motor
Estimated Stability Margin
without Motor
94
5.54
4
15
432
374
1.96
2.79
• Three parachutes (two
drogues, one main)
• Separates into two
sections
• Has an altitude control
mechanism
• Structure made of kraft
phenolic, with carbon
fiber reinforced sections
• Top speed of 490 ft/s
• Center of pressure at
altitude controller
Vehicle System - Subscale Rocket
• Three different launch
configurations:
1. Altitude controller deactivated
2. Altitude Controller activated
3. Payload bay with door
•
•
•
•
•
Interchangeable sections
0.4 Scale factor
2.276in diameter body-tube
Aerotech G78 Motor
1250ft Apogee
Vehicle System: Propulsion
• Cesaroni K1200 Motor
– Necessary impulse
– Subsonic
• Thrust to Weight: 9.9:1
• Rail Exit Velocity: 45 ft/s
– Stable flight
Max Thrust (lbs)
308
Avg. Thrust (lbs)
268
Burn Time (s)
1.69
Total Impulse (lbf-s)
452
Loaded Weight (lbs)
3.6
Empty Weight (lbs)
1.43
Simulations and Thrust Curve
Source
Peak Altitude (ft)
Peak Velocity (ft/s)
OpenRocket
3137
489
Structures System: Materials
• Nosecone: polypropylene plastic
– High compressive strength
• Airframe/couplers: phenolic and carbon fiber
– Standard high power rocket material
– Carbon fiber used in areas where extra support is
necessary
• Hatched Door
• Altitude Control System
• Fins: Aircraft plywood MIL-P-6070
– 0.2” thick
Structures System: Attachments
• Bulkheads/centering rings
– 0.5” thick Birch plywood
• Quick Links
– Rated at 2000 lbs
• Adhesives
– Long cure epoxy
– JB Weld
– Wood glue
• Success from previous years
Recovery System: Hardware
• Triple Deployment System
– 50” elliptical drogue parachute with bleed hole at
apogee
– 50” elliptical drogue parachute with bleed hole at
1,000 feet
– 96” elliptical main parachute with bleed hole at 650
feet
• Tubular Kevlar recovery harness
– 30 feet ~ 3 times length of rocket
Recovery System: Electronics
• Redundant Altimeters
– 2 Featherweight Ravens
– Independent power sources
– Shielded by RF absorbing tape
• Black powder ejection charges
– 2.3g for main
– 1.3g for drogue
– Ground test coming
Recovery System: Deployment Stages
1. Ascent
2. Drogue
Deploy at
Apogee
3. Payload bay separation and deployment of
second drogue at 1000ft
4. Main parachute deployment at 650 ft
Recovery System: Descent
• Descent Rates
– 36.3 ft/s under drogue
After rocket separates into two untethered sections
– 15.2 ft/s under main
– 21.5 ft/s under drogue
Section
Bottom Section (Main)
Weight (lbf)
Kinetic Energy (ft-lbf)
KE Margin
17.1
50.7
32.4 %
Hazard Bay (Drogue)
5.6
31.4
58.1 %
Nose Cone (Drogue)
1.7
2.9
96.1 %
Recovery System: Drift
• MATLAB recovery code
– Calculated using wind speed and descent time
Wind Speed:
0 mph
5 mph 10 mph 15 mph
Top Section
Under Drogue.
Drift (ft)
0
1157
2316
3473
Bottom Section
Under Main and
Drogue.
Drift (ft)
0
1248
2497
3746
Recovery System: CRAM
• Innovative concept replaces the
traditional avionics bay design
• Altimeters and power supplies
contained in 3D-Printed
Compartment
– Less than two inches in length, same
diameter as a coupler
– Dedicated cavities for each component
provide protection and organization
– Provides independent electromagnetic
shielding for each altimeter
Recovery System: CRAM
• Module is inserted in
body tube and rests on
small glued coupler
ring, fastened as well
by four screws
• Increases structural
integrity of the vehicle
(one solid body tube
for parachute bays)
• Arming screw switches
are accessible through
holes on the exterior,
yet are not fully
exposed and thus
better protected
Altitude Controller Payload
• Purpose: Increase drag
– Reduce rocket apogee
• Requirements: fast acting
– Minimal stability affects
– Must be reusable
• Terms of Success
– Apogee ≈ 3,000 feet
– No catastrophic failure of rocket
Altitude Controller: Design
•
•
•
•
•
“Skirt” design
Deployed by solenoids
Retracted passively by aerodynamic forces
Electromagnet locking mechanism
Controlled by Arduino Uno
– Accelerometer and altimeter for measurements
• Battery banks
• Support core and structural stringers
Altitude Controller: Aerobraking Tabs
• 0.41”x1.5” rectangular tabs
• Four pairs of tabs
– Equally spaced around the fuselage
•
•
•
•
Held in place by electromagnets at launch
Each tab deployed by its own solenoid
The tabs will hinge out in a “skirt” design
Retracted passively by aerodynamic forces
Altitude Controller: Solenoids
•
•
•
•
Eight linear “pull” solenoids
Require 12 V and 8.4 W each
Rechargeable batteries in series
Generate 1.94 lbf at 0.25” stroke
– Sufficient for needed tab design
• Expect high reliability under operating
conditions
Altitude Controller: Electromagnets
• Located within fuselage
• “Latch” tabs closed during powered flight
• Prevent unequal/premature deployment of tabs
– Unequal deployment → loss of stability
– Premature deployment → structural failure
Electronic Control System
• Built around Arduino Uno
• Measure time, altitude and
acceleration
• Calculate velocity and
predicted apogee
• Deploy tabs to adjust apogee
accordingly
LIS331 Accelerometer
MPL3115A2 Altimeter
Altitude Controller: Control Algorithm
•
•
•
•
Tabs deployed immediately after burnout
Apogee calculated using work-energy equations
Continuous apogee calculations during flight
Once predicted apogee reaches 3,000 ft.
– Solenoids are powered off
– Tabs retract and are re-locked
Altitude Controller: Power Control System
• Relays controlled by the Arduino to connect and
disconnect the solenoids and electromagnets to
power
• Additional relay to connect the Arduino to power
controlled by main flight computer
Altitude Controller: Structural Support
• Payload design requires changes to fuselage
• Measures to maintain structural stability
– Four metal rods acting as stringers
– Wooden support structure
• Run the length of tabs
Verification
• Electronics System
– Simulations
– Flight testing
• Physical Mechanism
– Ground Testing
– Wind Tunnel
– Full Scale Test Flight
Aerodynamic Payload Subsystem
Verification Plan
Subsystem
Requirements
Verification Method(s)
Arduino/Sensors
Record and store data
throughout flight.
Small scale flight test, full
scale flight test.
Control Algorithm
Successfully predict apogee
and signal controller
activation.
Team created simulation
program.
Physical Mechanism
Control ascent to target
altitude.
Simulation paired with
sensor test data.
Arduino/Motor activation
Activate motor according
to control algorithm.
Ground testing, small scale
flight test, full scale flight
test.
Communications System
Divided into 5 sections
1. Primary Control Unit
2. Secondary Control Unit
3. Radio Frequency Downlink System
4. Power Management Systems
5. Ground Station
Comm: PCU/SCU
• Responsible for managing all electronic aspects
of the rocket
• Capabilities include:
– Accept commands from ground station. Critical for
maintain 2 hour battery life while on pad
– Detect separation of rocket
– Collect all data/telemetry for transmission
Comm: PCU/SCU Communication
• Two Xbee modules used for short range
transmissions (~1000m)
• SCU → PCU → RFDS → Ground Station
• Halves of the rocket can communicate before
and after separation
• Xbee on ground station can also receive
transmissions from close range if needed
• Very efficient control system
Comm: Radio Frequency Downlink
• Link between the rocket and the ground station
• Transmitter is:
– Baofeng UV-5r - 145.750 MHz - 4 W
• One student, Benny, has a technician amateur
radio license, but looking to expand
• Compliant with amateur radio rules
– Station ID is broadcast with each packet sent
• Radio power extensively tested
Comm: Power Management System
• Critical that all electrical systems maintain
power for 2+ hours
• NiMH battery pack to be used for the following:
– PCU/SCU (arduino)
– Altitude controller
– Any other systems necessary
• NiMH battery packs rechargeable and allow for
higher current
Comm: Ground Station
• LCD Displays:
– Display GPS data, sensor information, voltages, etc.
• Control Panel:
– Uses switches to turn on various functions of the
system
– LEDs will verify proper functionality of payload
– Robust confirmation system to prevent errors (or
notify user if unavoidable/unfixable)
AGSS: Concept Features & Definition
• Creativity and originality
– Subsystems of AGSS
– Modular launch pad
• Uniqueness and significance
– Technology for Martian environment
• Suitable level of challenge
– Team’s first time developing an autonomous system
to launch a rocket
AGSS: Science Value
• Objectives
– Fully autonomous
procedures
– Payload integration
– Rail erection
– Igniter installation
– Within 10 minutes
– Systems must work in a
Martian environment
• Success criteria
– Schedule
– Quality
– Functionality
• Accuracy
• Consistency
AGSS: Science Value
• Experimental logic
– Minimize points of error
– Simplify systems
• Approach
– Compartmentalization
• Method of
investigation
– Separated tasks
– Developed systems
• Test and
measurement
– Structural
– Capability
• Variables
– Consistency and
accuracy
– Environment
• Controls
– System specifications
– Functionality and
objective
– Order of operation
AGSS: Science Value
• Relevance of
expected data
– Will determine
consistency of system
• Accuracy/error
analysis
– Programming motor
movement
– Error in physical build
• Preliminary
experiment
process
procedures
–
–
–
–
–
Finalize designs
CAD Models
Component selection
Prototyping
Testing and tuning
Requirements Verification
• Recovery
– Commercially available altimeter
– 2 untethered sections, each under 75 ft-lbs. at landing
• Launch Vehicle
–
–
–
–
2 hour preparation time
Can sit on pad for 2 hours
Full scale and subscale test will be completed
Checklists used
• AGSS
– Completely autonomous
– Pause Switch
Testing Plan: Recovery
• Ground testing
– Altimeters
– Black powder
– Electrical Interference
Testing Plan: Vehicle
• 3 Subscale flights planned
• Two full scale test flights planned
1. January 17 flying qualities, controller,
communications
2. February 14  AGSS, Contest Rehearsal
Questions?