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Water Bottle Rocket Team 9: Darren Combs, Lauren Darling, Andrew Moorman, Esteben Rodriguez, Amanda Olguin
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OVERVIEW Sensitivity Adjustments Modified Rocket Predictions Results
Introduction Static Testing Methods Baseline Rocket MATLAB Rocket Design Sensitivity Adjustments Modified Rocket Predictions Results Lessons Conclusions Team 9
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Introduction Goal Process model manufacture Fly analyze
Apply previous aerodynamic and thermodynamic knowledge to build a bottle rocket trajectory code Process Team 9
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Overall Concepts 3 (4) Phases of flight Drag, thrust and weight
Depends on model used Drag, thrust and weight The rocket fins will align themselves parallel to free stream Assumption: rocket will point into the wind Team 9
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Governing Equations πΉ=0 π π
= π π΅
πΉ= π π π π π΄ π‘ π π 2 +( π π β π π ) π΄ π‘ Phase 3 Phase 2 πΉ= π π π +( π π β π π ) π΄ π‘ Phase 1 Team 9
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Static Testing Allows measurement of the total force that is exerted throughout firing Load Cells push against a stationary structure with a load cable attached that measure force Long string of data is cut down and then adjusted in order to correctly approximate Isp βπ= πΌ π π π 0 lnβ‘( ππππ‘πππ πππ π πππππ πππ π ) Team 9
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Wind tunnel π·πππ= 1 2 π π β 2 π π π΄ π΅ The wind tunnel allows us to come up with a coefficient of drag for our rocket. Spinning vs. non-spinning rocket: making a rocket spin provides stability. Solve for Cd π π =2β π·πππ π π β 2 π΄ π Team 9
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Baseline Rocket 4 fins Set parallel to the airflow close to the nozzle
triangular in shape 3.25 inch base by 3 inch height Set parallel to the airflow close to the nozzle Payload consist of an altimeter and packing peanuts (27 grams) Weight of rocket: 160 grams Payload hub is at the nose of the rocket encapsulated by extra casing (bottom of a 2 liter bottle) Payload nose of rocket included holes for accurate pressure readings Team 9
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Thermo Model Pros: Cons: Takes into account most variables
So many inputs to keep track Most are variable throughout Team 9
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Thermodynamic Matlab modeling
Input Values Wind tunnel data Initial conditions Wind conditions ODE 45 Results & Plots Team 9
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Isp Model Pros: Cons: Easiest to model
Ballistic for majority of launch Cons: Initial ΞV gives rocket initial momentum propelling it to go further. Team 9
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Isp MATLAB Modeling Input Values Set Conditions
Upload Wind Tunnel Data/ Compute Drag Upload Static Test Data / Compute ο³V Adjust Wind Data ODE 45 Plots/ Angle Computation Outputs Team 9
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Interpolation model Pros: Cons: Pulling real thrust values
Interpolation/finding values gets tricky Data collection is very sensitive Team 9
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Interpolation MATLAB Modeling
Input Values Set Conditions Upload Wind Tunnel Data/ Compute Drag Adjust Wind Data Upload Static Test Data / Compute Thrust ODE 45 Plots/ Angle Computation Outputs Team 9
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Sensitivity adjustments
Exit Area 20.7 ft increase per 1 in decrease of diameter exit 15.5 ft increase per 0.1 decrease in Cd 48.5 ft increase per 1 kg decrease in water mass 0.011 ft increase per 1 kg/m^3 decrease of water density 3.38 ft increase per 1 psi increase of pressure Drag Coefficient Water Mass Water Density Pressure Team 9
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Modified Rocket design
How did you choose your design? Changing water fraction yielded the highest range change The final design became the base TA rocket with an adjusted water mass of 600 grams. Team 9
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Uncertainties Random Gaussian Wind Wind Angle Temperature Air Density
Water β 2 grams Pressure β 1 psi Cd β 0.2 Thrust (Interp model) β 10 lbf Launch Stand β 1 degree Initial Velocity (ISP model) β 10 mps Angle Finder β 5 degrees Time of Flight β 1 sec Team 9
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Thermodynamic Flight Prediction
Semi major Axis: 271 ft Semi minor Axis: 127 ft Data scatter represents 100 runs Team 9
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ISP Flight Prediction Semi major Axis: 389 ft Semi minor Axis: 130 ft
Data scatter represents 100 runs Team 9
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Interpolation Flight Predictions
Semi major Axis: 34.4 ft Semi minor Axis: 31.4 ft Data scatter represents 100 runs Team 9
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Results from Launches 4/16 Max Height Distance Deflection Duration S1
Β 4/16 Max Height Distance Deflection Duration S1 S2 S3 Actual NA 233β8β 4Β° Left 4.7 sec 31Β° 36Β° 28Β° Isp 189β10β 323β2β 4.1Β° Right 5.3 sec 56.7Β° 30.2Β° 23.7Β° Interp 72β8β 199β7β 6.9Β° Right 3.9 sec 62.9Β° 16.8Β° 11.2Β° Thermo 44β7β 165β 58Β° Right 3.1 sec 50.9Β° 10.5Β° 6.8Β° Altimeter Launch Angle: 45Β° Pressure: 40 PSI Water: 600g Wind speed: 5 mph from ENE Launch Angle: 45Β° Pressure: 40 PSI Water: 530g Wind speed: 7 mph from NNE Β 4/16 Max Height Distance Deflection Duration S1 S2 S3 Actual NA 206β6β 0Β° 4.54 sec 32Β° 40Β° 31Β° Isp 195β3β 323β10β 6.0Β° Right 5.3 sec 33.8Β° 27.6Β° Interp 95β6β 222β 9.9Β° Right 4.3 sec 24.1Β° 24.2Β° 16.6Β° Thermo 64β1β 157β 39.2Β°Right 3.6 sec 18.3Β° 18.4Β° 11.6Β° Altimeter Team 9
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Results from Launches Launch Angle: 45Β° Pressure: 40 PSI Water: 600g
Wind speed: 2 mph from S Β 4/21 Max Height Distance Deflection Duration S1 S2 S3 Actual NA 211β 0Β° 4.24 sec 26.5Β° 28Β° 36Β° Isp 186β3β 310β 0.8Β° Right 5.2 sec 33.5Β° 33.6Β° 27Β° Interp 29β7β 74β4β 3.5Β° Right 2.6 sec 10.1Β° 10.2Β° 5.3Β° Thermo 77β8β 140β10β 18.3Β°Right 3.9 sec 24Β° 24.1Β° 14.6Β° Altimeter 84β 4.64 sec Β 4/21 Max Height Distance Deflection Duration S1 S2 S3 Actual NA 221β 4Β° Left 4.83 sec 35Β° 32Β° 23Β° Isp 192β10β 328β9β .3Β° Right 5.4 sec 55.4Β° 29.9Β° 23.7 Interp 134β5β 268β9β 4.8Β° Right 4.9 sec 28.8Β° 28.7Β° 21.6Β° Thermo 60β 162β8β 3.3Β° Right 3.5 sec 57Β° 15.2Β° 9.7Β° Altimeter 89β10β 4.69 sec Launch Angle: 45Β° Pressure: 40 PSI Water: 600g Wind speed: 2 mph from NNE Team 9
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Altimeter Data Altimeter data
Raw Data Adjust and Zero data to flight Pressure Altitude Converter to find height Altimeter data Validation of code comes from comparing it to the data accrued from the various launches the rocket performed. Subtract altitude of launch site to find height of launch Team 9
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Lessons learned Parameters that likely had the greatest effect on the flight in our case was water fraction and PSI. Donβt give rockets to small children as it is possible fins will be removed. Rockets that are unstable can be stabilized if fins are oriented to spin the rocket. The process of physically manufacturing and testing a model design. Team 9
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Discussion/conclusions
Greatest Uncertainty Factors: Wind, Initial momentum, Exit coefficient, integration techniques. Interpolation Model performed most accurately to our launch results Error issues come from the difficulty in modeling each factor and the configuration of air holes for the payload Future Improvements: Find scientific way to determine coefficient of friction on test stand. Soap is rather viscos. Maximize height of rocket along with distance. Team 9
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sources Wind Tunnel Rocket Test Procedure. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. Static Test USB VI Procedure. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. Static Test Firing Procedure. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. Launch Pad Procedure. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. TA Rocket Specifications. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. Rocket Lab Presentation Criteria. Boulder: University of Colorado Aerospace Engineering Sciences Department, 27 Apr PDF. Team 9
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