The Comparative Analysis of Airflow Around a Rocket
Dec 30, 2015
MAJOR MILESTONE SCHEDULE
• March 21 Second test flight of full-scale vehicle
• April 12 Rocket ready for launch• April 16 Rocket Fair/Hardware & Safety check• April 19 SLI Launch Day
1. First stage burn 2. Stage separation.3. Booster coasts to its apogee
and deploys main parachute.4. Booster lands safely5. Second stage motor burn6. Sustainer reaches apogee,
deploys drogue parachute7. Sustainer descends under
drogue parachute to 700ft 8. Main parachute deploys,
slowing rocket to safe landing speed of 15-20 fps.
9. Sustainer lands safely.
FLIGHT SEQUENCE
SUCCESS CRITERIA• Stable launch of the vehicle • Target altitude of one mile reached• Smooth stage separation. • Proper deployment of all parachutes• Safe recovery of the booster and the
sustainer
Length 156.5”Diameter 6”Liftoff weight 37.4 lb.Motor K1275 Redline (54mm)
CP 118.8” (from nosetip)CG 101.8” (from nosetip)Static Margin 4.23 calibers
ENTIRE ROCKET
Length 94”Diameter 4”Liftoff weight 12.7 lb.Motor J380 Smokey Sam (54mm)
CP 83.8” (from nosetip)CG 63.6” (from nosetip)Static Margin 5.04 calibers
SUSTAINER
Letter Part Letter PartA Nosecone H Payload Bay
B Main Parachute I Payload Electronics
C Sustainer E-Bay J Drogue Parachute
D Fins K Motor Mount
E Transition L Main Parachute
F Booster E-Bay M Payload Electronics
G Fins N Motor Mount
ROCKET SCHEMATICS
• Fins: 1/32” G10 fiberglass + 1/8” balsa sandwich• Body: fiberglass tubing, fiberglass couplers• Bulkheads: 1/2” plywood • Motor Mount: 54mm phenolic tubing, 1/2” plywood
centering rings • Nosecone: commercially made plastic nosecone• Rail Buttons: large size nylon buttons• Motor Retention system: Aeropack screw-on motor retainer• Anchors: 1/4” stainless steel U-Bolts• Epoxy: West System with appropriate fillers
CONSTRUCTION MATERIALS
Booster SustainerFlight Stability Static Margin
4.23 5.04
Thrust to Weight Ratio 6.15 5.29
Velocity at Launch Guide Departure:
54 mph(launch rail length 144”)
FLIGHT SAFETY PARAMETERS
Wp - ejection charge weight in pounds. dP - ejection charge pressure, 15psiV - free volume in cubic inches. R - combustion gas constant, 22.16 ft- lbf/lbm R for
FFFF black powder.T - combustion gas temperature, 3307 degrees R
EJECTION CHARGE CALCULATIONS
Ejection charges have been verified using static testing.
CALCULATED EJECTION CHARGES
Section Ejection ChargeBooster 2.15 g (of FFFF black
powder)Sustainer (Drogue) 2.0 g
Sustainer (Main) 3.15 g
Stage Separation Charge 1.0 g
Component Weight Parachute Diameter
Descent Rate
Booster(predicted)
399 oz 92 in.(main)
17.6fps
Sustainer (measured)
211 oz 24 in.(drogue)
54.7 fps
Sustainer(measured)
211 oz 60 in.(main)
17.5 fps
PARACHUTES
Tested Components
• C1: Body (including construction techniques)• C2: Altimeter• C3: Data Acquisition System (custom computer board and sensors)• C4: Parachutes• C5: Fins• C6: Payload• C7: Ejection charges• C8: Launch system• C9: Motor mount• C10: Beacons• C11: Shock cords and anchors• C12: Rocket stability• C13: Second stage separation and ignition electronics/charges
VERIFICATION MATRIX
Verification Tests• V1 Integrity Test: applying force to verify durability.• V2 Parachute Drop Test: testing parachute functionality.• V3 Tension Test: applying force to the parachute shock cords to test • durability• V4 Prototype Flight: testing the feasibility of the vehicle with a scale model.• V5 Functionality Test: test of basic functionality of a device on the ground• V6 Altimeter Ground Test: place the altimeter in a closed container and decrease air pressure
to simulate altitude changes. Verify that both the apogee and preset altitude events fire. (Estes igniters or low resistance bulbs can be used for verification).
• V7 Electronic Deployment Test: test to determine if the electronics can ignite the deployment charges.
• V8 Ejection Test: test that the deployment charges have the right amount of force to cause parachute deployment and/or planned component separation.
• V9 Computer Simulation: use RockSim to predict the behavior of the launch vehicle.• V10 Integration Test: ensure that the payload fits smoothly and snuggly into the vehicle, and
is robust enough to withstand flight stresses.
VERIFICATION MATRIX
VERIFICATION MATRIXV 1 V 2 V 3 V 4 V 5 V 6 V 7 V 8 V 9 V
10
C 1
C 2
C 3
C 4
C 5
C 6 P P
C 7
C 8
C 9
C
10
C
11
C
12
C13
• Liftoff Weight: 34 lbs
• Motor:Booster K1100 T
Sustainer I599N
• Length: 157 inches
• Diameter: 6in
• Stability Margin: Booster 4.53
Sustainer 5.88
Vehicle Parameters
• Test dual deployment avionics
• Test full deployment scheme
• Test validity of simulation results
• Test rocket stability
• Test staging scheme
Flight Objectives
• Apogee: 2519 ft– RockSim Prediction: 2479 ft
• Time to apogee: 12 seconds
• Apogee events: drogue
• Sustainer main parachute: 700 ft
Sustainer Flight Results
Apogee Events
Sustainer Main Parachute Deployment
Sustainer True Apogee
Sustainer Flight Data
Temporary Altimeter #2Power Failure
BoosterApogee
Description Initial Pointtime, altitude
End Pointtime, altitude
Descent Rate
Sustainer Descent with Drogue
13.5s, 2466ft 54.5s, 700ft43.0 fps
Sustainer Descent with Main
58.0s, 588 ft 97.5s, 0ft 14.9 fps
Booster Descent with Main (unopened)
10.6, 845ft 18.7, 0ft 104 fps
Measured Decent Rates
Recorded data
Simulation results(updated CD)
Apogee = 2519ft
Apogee = 2479ft
Flight Simulations vs. Data
EXPERIMENT CONCEPT• We will use an array of pressure sensors to
observe the airflow characteristics around several obstacles during a two stage flight.
• After flight, we will test the rocket in a wind tunnel and compare the results.
EXPERIMENT CONCEPT
Artificial protrusions (obstacles) will be placed on the sustainer body to create disturbances in airflow.
Airflow
Pressure sensors will measure the local pressure before and after the protrusions
PAYLOAD OBJECTIVES
• Determine the effect of obstacles on the surface of rocket on airflow around the rocket
• Determine the accuracy of wind tunnel testing
PAYLOAD SUCCESS CRITERIA
• Obstacles remain attached to the rocket during flight.
• Sensors will successfully collect and store measureable data during flight.
• Data collected is reliable and accurate.
The payload will measure the airflow around the rocket using an array of
pressure sensors.
The location of the pressure sensors are shown in red and obstacles are shown in
blue.
DATA ACQUISITION
Sampling rate: 100 times per second
Sampling resolution: 16 bits(2 LSB noise expected)
100kPa full scale range(15kPa ~ 115kPa)
Sampling locations: 12 on sustainer and 12 on booster
DATA ACQUISITION
DATA CONNECTIONSEach data acquisition board (DAB) reads and stores data from 6 pressure sensors
Analog signals from the sensors are carried to the digitizer (ADC) using a shielded cable
All DABs in the same stage are activated by the same G-switch
shielded cable
Common G-switch
sensor
Dataacquisition
Electronics
Data Acquisition Board: controls signal digitization, receives and storesdigitized data from pressure sensors
Sensor Board: hosts a single pressure sensor and signal conditioning (noise suppression) circuitry
Electrical schematics for DAB: shows the components and connections between them
SUSTAINER
Diagram of the sustainer showing the payload integration.
DPSUnit
TimerAlt
Sensor package Parachute Compartment
BOOSTER
Diagram of the Booster showing the payload integration.
Fin Tab
Fin
Motor
Alt
Alt
Parachute
DPS&S
Parachute Compartment
VARIABLES• Independent Variables
– Type and location of obstacles………….…. L– Air density outside of rocket……..……..…. D– Speed of air flow…………………………………. S– Air pressure………………………………………… P– Acceleration profile…………………………….. X,Y,Z
• Dependent Variables– Pressure at each sensor………….………….. Yi
CONTROLS• Identical rocket in wind tunnel and actual flight
• Identical obstacles on rocket in wind tunnel and actual flight
• Similar wind speeds in wind tunnel and actual flight of first stage
• Identical sensors and method of data storage
CORRELATIONS• Primary correlations
– Yx = f(L) (local pressure vs. location) – Yx = f(S) (local pressure vs. airspeed) – Data from wind tunnel test and actual flight will be
compared
• Further correlations from actual flight– pressure vs. selected independent variables
TEST AND MEASUREMENT
Test Measurement
Pressure Pressure will be collected at least 100 times per second by the sensor array
VERIFICATION MATRIXComponents
1.Pressure Sensors2.Battery Pack3.Altimeter4.3D Accelerometer5.Obstacles
Verification Tests
1. Drop Test2. Connection and Basic
Functionality Test3. Pressure Sensor Test4. Scale Model Flight5. Durability Test6. Acceleration Test7. Battery Capacity Test
VERIFICATION MATRIXP=PLANNEDF=FINISHED
T E S T S
1 2 3 4 5 6 7
COMPONENTS
1 F F P
2 F F F
3 F F F F F
4 F F F P
5 F F F
RELEVANCE OF DATA, ACCURACY AND ERROR ANALYSIS
Simulated pressure profile at 100mphPredicted pressure changes: -400Pa .. +300Pa
RELEVANCE OF DATA, ACCURACY AND ERROR ANALYSIS
Simulated pressure profile at 250mphSimulated pressure profile at 250mph
Predicted pressure changes: -2,000Pa .. +1,500Pa
RELEVANCE OF DATA, ACCURACY AND ERROR ANALYSIS
Resolution: true 14 bit(16 bit digitization with 2 LSB noise)
14 bits = 16,384 signal levelsSensor range: 100,000Pa (15,000 – 115,000Pa)
100,000Pa / 16,384 levels = 6.10Pa / level
Expected pressure differences:
@ 100mph: -400Pa ~ +300Pa 114 levels @ 250mph: -2,000Pa ~ +1,500Pa 573 levels