University of Florida FRR Presentation

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Vehicle Design Changes The weight has increased from 26.3 lbs to 28.0 lbs due to underestimating the mass of the payload Because of the weight of the payload is larger, a 36” drogue parachute must be used for the payload drogue instead of streamers. A 60” X-type is used for the main parachute The mid airframe has been reduced from 30 inches to 15.75 inches. This leads to a total rocket length of 111.75 inches

Static Stability Diagram CP CG The center of gravity is located 69.7 inches from the nosecone The center of pressure is located 81.3 inches from the nose cone The maximum diameter of the rocket is 5.54ʺ. These dimensions result in a stability margin is 2.22

Upper Airframe Features 45” length Contains piston, payload, payload drogue, rocket drogue, and nose cone insert Shoe - centering ring inside UAF Protects avionics bay from payload bay Camera cover Contains mirror to deflect Avionics camera image downwards Holes for on switch, indicator lights

Avionics Bay Features 10” long Threaded inserts to stay fixed to UAF and MAF Easy Assembly with alignment notches Threaded Inserts Alignment notches

Avionics Bay Features Easy Ejection charge hookup with terminals on top and bottom of bulkhead Redundancy PerfectFlite altimeters Switches 9V batteries e-matches Video Camera GPS and transmitter (still to be installed)

Mid Airframe Features 15.75” long Contains Main Parachute 12” coupler glued to connect to LAF

Lower Airframe Features 30” long Contains motor mount, 3 centering rings, motor retention device 3 Fins mounted through the airframe to the motor mount 2 launch rail slides (for 1” 80/20 rail) Additional Mass compartment in between top and middle centering ring

Motor Choice The Loki L1400 will be used Characteristics of the L1400 Total Impulse: 2850.6 Ns Peak Thrust: Officially 2710.5 N, but RockSim reports 1906.4 N, large discrepancy Burn Time: 2.0 s Performance w/ Rocket Thrust-to-weight ratio: 11.1 Rail-exit-velocity: 72.4 ft/s (with 7 foot rail)

L1400 Thrust Curve Source: thrustcurve.org

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Payload Housing and Integration 4 legs separated ninety degrees from each other around the circumference of the payload tube Each leg consists of a “primary” leg, a “support” leg, and a “secondary” leg 4 sets of “shoulders” are welded to the tube

Payload Leg Design Slots in primary leg Support arm connected to slot with steel pin Slot allows primary leg to slide in so that the payload can fit inside rocket Linear spring pulls slot-pin down so that legs tend to spring out Slot Linear Spring

Linear Spring Force At rest (landing position): spring length is 2.4” In full tension (folded position) spring length is 4.4” 2 inches of elongation The spring constant is 3.99 lbs/inch The initial force is 1.75 lbs. Equation: f=kx+1.75 f=3.99(2)+1.75= 9.73lbs Linear Spring

Payload Leg Design Secondary leg added to dampen impact Attaches to end of primary leg; folds up over primary leg Torsion spring adds to dampening Torsion Spring

Spring dampening 1.51 lbs. for 45° deflection (experimentally measured) The spring deflection when secondary legs are flush with the ground is 46.5° 1.56 lbs. from each torsion spring, or 6.24 lbs total, if all secondary legs are flush with the ground. Torsion Spring 46.5°

Payload Leg Stress Analysis landing RDAS reported 60 g landing during subscale flight This corresponds to a 408 pound force for the full scale payload landing Dividing this among the four legs, each leg experiences 102 pounds of impact force

Payload Leg Stress Analysis Abaqus, finite element analysis software, was used to create a model of the legs Support leg parallel to x-axis, primary leg parallel to y-axis The equivalent force was applied to the end of the primary leg Boundary conditions applied to the shoulder connections Support leg Element breakdown Node breakdown Primary leg

Stress Analysis Results All stresses under the yield stress of the material (46ksi) Highest stress at support leg-primary leg joint (22.8ksi) Concern: the highest stress is located at the slot Reaction force at slot is 206 pounds

Shear Stress in Pins Cross sectional Area, A is .0491 in2 The force in the slot, F is 206 lbs The shear stress, τ, is equal to F/A τ = 4.195 ksi Pin material – 18-8 Stainless steel, Yield Strength of 30 ksi Pins will not yield under stress, S.F. of 7.15

Payload Electronics Contains two R-DAS Tiny altimeters (w/ redundant switches and e-matches) that control the payload’s main parachute deployment and record all sensor data. Each R-DAS Tiny has its own battery (for the full scale test, a PerfectFlite was used in place of one RDAS) Contains two analog temperature and two analog humidity sensors Contains a GPS and transceiver powered by an 11.1V battery

Payload Wiring Schematic

Outline Vehicle Design Payload Design Recovery System Component Testing Full scale Flight Simulations Outreach Future Work

Recovery Method Two separate recovery systems because of payload separation Redundant PerfectFlite altimeters will control the rocket’s dual deployment Redundant R-DAS Tiny altimeters will control the payload’s dual deployment All altimeters will have their own switch, battery, and e-match for full redundancy Rocket Drogue: 36” round Descent Rate: 64 ft/s Rocket Main: 96” round Descent Rate: 21 ft/s Payload Drogue: 36” round Descent Rate: 32 ft/s Payload Main: 60” X-type Descent Rate: 12 ft/s

Ejection Charge Amount Test Apogee deployment Has to push out piston, payload, both drogue chutes, and the nose cone 8 grams was determined sufficient Main chute deployment Has to push apart the Lower and Middle airframe, break the shear pins, and eject the main parachute 7 grams was determined sufficient

Ejection Charge Amount Test Apogee Deployment Video

Ejection Charge Amount Test Main Deployment Video

Dual Deployment Avionics Test The PerfectFlite altimeters have been tested and proven in static tests and in the subscale and full scale flights The RDAS still needs to be tested on the ground thoroughly to ensure that it will ignite the ejection charges appropriately

Payload Main Parachute Ejection System The main parachute is secured to the bottom in a parachute pack Is deployed by pulling the ripcord which in turn pulls a pin holding the pack together Ripcord is attached to a slug which is shot out of the ejection tube A cable secures the slug to the payload.

Payload Main Parachute Ejection System The pin attached to the ripcord holds the four flaps of the parachute pack in place until the ejection sequence is initiated

Payload Main Parachute Ejection System Video of Ejection Charge Test

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Payload Bay Testing The predicted load on the “shoe” was tested 75 pounds of total predicted force No damage occurred during static test or full scale flight Payload leg testing Legs spring open once separated from the rocket Load testing on slot in primary leg Static Shoe-load test

Payload Leg Opening Test

Load Test on Slots Weights were hung from the slots of an extra primary leg 30 lbs to yield for ½ of the slot, so 60 pounds overall 170 lbs to failure for ½ half of the slot, so 340 lbs overall Assuming the stress analysis is close to actual, the slot will yield during the payload landing but will not fail Yielding is not a mission failure, so this is acceptable

Payload Testing Temperature and humidity sensor testing complete by seeing change in voltage in varying temperature and humidity climates GPS and transceivers have been tested statically and in motion RDAS altitude data was comparable to the PerfectFlite in the 1st subscale launch

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Full-Scale Flight March 19th, at TTRA field 0-5 mph calm winds Successful deployment of drogue chutes and payload at apogee Rocket’s main parachute was deployed at apogee because shear pins were dislodged during the event Payload main chute deployed at appropriate altitude of 500 feet. Lander suffered minor damages during landing but no failure occurred. It was determined reusable

Full-Scale Flight Video

Full-scale Altitude Results Two PerfectFlite altimeters in the avionics bay, PF1 and PF2 PF1 reported max altitude of 3794 ft PF2 reported max altitude of 3752 ft Both altimeters ran out of memory before landing, due to early chute deployment

Full-scale Altitude Results One PerfectFlite in the payload, PF3 Max altitude measured as 3797 ft The spike at apogee shows that airflow passed around piston during the rocket’s first ejection charge Drogue descent: ~32 ft/s Main descent: ~12 ft/s

Full-scale Altitude Results Possible causes for not reaching a mile Initial launch angle 18.75 oz. of clay in additional mass compartment Drag coefficient uncertainty Thrust uncertainty Total mass uncertainty

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Initial Flight Simulations Wind Condition (mph) Launch Angle (°) Mass Added (oz.) Max Altitude (ft) Downrange landing (ft) Stability Margin 13 5280 2.09 2.5 196 5 12.5 418 2.10 7.5 12 654 10 11 749 2.11 6.5 547 2.16 15 4.5 735 2.18 17.5 5228 641 2.22 20 5187 897 RockSim was used to predict the flight performance of the rocket The effect of wind condition on altitude was investigated Launch angle was changed so that the downrange landing stayed below 1000 ft The mass added to the rocket to achieve a mile was calculated for each wind condition/launch angle combination

Coefficient of Drag RockSim predicts that the drag coefficient changes with velocity CD approaches 0.448 at zero speed to .337 at max speed of 665 ft/s Equivalent drag coefficient constant: 0.37 Full Scale Test Flight maximum altitude using the CD from RockSim: 5215 ft The drag coefficient was fit to full scale flight so that the maximum predicted altitude matched the actual maximum altitude (about 3790 ft). New constant CD = .814 The flight simulations were performed again, this time with the new CD Velocity (ft/s)

Flight Simulations w/ New CD Wind Condition (mph) Launch Angle (°) Mass Added (oz.) Max Altitude (ft) Downrange landing (ft) Stability Margin 3934 2.22 2.5 3933 187 5 3930 378 7.5 3924 578 10 3916 765 12.5 3871 663 15 3853 819 17.5 3773 646 20 3746 883 Flight simulations repeated for adjusted CD = .814 According to simulations, the maximum altitude cannot reach a mile with the current design The team will discuss possibilities of reducing the mass and CD

Time to Apogee and Velocity Time to Apogee for Full Scale Test Launch RockSim predicts about 14.5 seconds Flight data shows between 16.2 and 17.1 seconds Velocity during burn time

Velocity The velocities were calculated with the central difference method Velocities for the avionics bay altimeters approached the transonic region and were greater than the payload altimeter during the motor burn time

Velocity The data from the avionics bay (PF1) showed a much higher peek in velocity than predicted The RockSim prediction resembled the data from the altimeter in the payload bay (PF3) more closely than the one in the avionics bay (PF1)

Location of Altimeters Payload Altimeter Avionics Altimeters Compressible flow phenomena like oblique shocks or expansion waves could be the cause of the pressure difference between the avionics altimeters and the payload altimeter

Returning to MATLAB 1DOF Both MATLAB and RockSim gave poor predictions of the actual altitudes and velocities experienced by the rocket Largest uncertainty remains in the drag coefficient Goal is to produce a model: CD - Total Drag Coefficient CDO- Initial Drag Coefficient (obtained from literature) CD(Ma) - Drag Coefficient as a function of free stream Ma

Curve-fitting Techniques As a first approximation we used a model: The velocity obtained using numerical differentiation of the PF1 altimeter was fitted with a fifth-order polynomial: The result was scaled to by the CD0 to achieve CD(t)

First Approximation Results Significant improvement in both rise time and altitude Rise time of 15.9 s. Error reduced to about 5.4% Maximum altitude of 3869 ft. Error reduced to about 2.5% Potential problems Repeatability with different launch angle, wind, etc No ability to predict the altitude before a full scale launch

Compressible Flow Correction Next, we attempt to use a similar expression to the Prandtl-Glauert rule to predict drag coefficient as a function of free-stream Mach number The result is not as accurate as the curve-fitting techniques Rise time: 15.5 s. Error: 6.9% Altitude: 4305 ft. Error: 14.1%

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Educational Engagement Presented to 150 5th graders at Hidden Oak Elementary School in December Presented to sixty 4th-8th graders at Millhopper Montessori School (private school) in January PowerPoint presentation taught students about the basics of rocketry, how to get involved, and how to remain safe Three model rockets were launched to give the students an first-hand example of rocketry

Educational Engagement Shared a booth with AIAA during Engineering Fair Students from middle and high schools from around Gainesville came and were shown two separate rockets and their various components There were also water-bottle rocket launches every half hour

Educational Engagement Presented to 110 8th graders at Howard Bishop Middle School on February 24th The same PowerPoint presentation used for the previous school presentations was used which covered the basics of rocketry, how to get involved, and how to remain safe Three model rockets were once again launched to get the students excited about rocketry

Educational Engagement Upcoming event: Aerospace Day, March 31st Event conducted by UF AIAA student chapter Middle School students from the Gainesville area will come to UF and learn about Aerospace Engineering There will be various hands-on activities such as launching small rockets, as well as tours of on-campus labs

Outline Vehicle Design Payload Design Recovery System Component Testing Full-Scale Flight Simulations Outreach Future Work

Payload Testing Solar and UV sensor testing RDAS testing Solar cell voltage to W/m2 conversion constant UV sensor voltage to W/m2 conversion constant (1.962) RDAS testing Duration of data storage Ejection charge testing

Recovery System Testing Additional full scale ejection charge ground testing Need to make sure main deployment ejection charge can overcome additional shear pins Payload landing testing At a maximum allowable velocity of 22 ft/s With horizontal motion, rotation, and tilt angles GPS testing in aluminum Payload Bay tube

Static Motor Testing The static motor test has been postponed until next week. The L1400 will be tested on a test stand provided by our mentor, Jimmy, which is capable of such large motors. This test will: help verify which motor characteristics that should be trusted- the official one provided by the NAR or the one provided by RockSim be used to adjust our flight simulations The motor will also be tested with the retention device connected, just in case it effects the exhaust flow at all

Possible changes Reduction of weight by removing material, so that flight simulations show we can reach a mile Reduction of drag coefficient by painting the rocket and closing off the aft end of the rocket (possible separation or recirculation effects)

Questions?