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UNIVERSITY OF MINNESOTA TWIN CITIES

2012 – 2013 University Student Launch Initiative Post Launch Assessment Review

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2012-2013 University of Minnesota Team

Mark A.

Senior, Aerospace Engineering and Mechanics, Team Lead

Aboto001@umn.edu

Amir E.

Senior, Aerospace Engineering and Mechanics, Financial Officer

Devin V.

Senior, Aerospace Engineering and Mechanics, Structural Lead

Tim C.

Junior, Aerospace Engineering and Mechanics, Structural Team

Nathan K.

Senior, Aerospace Engineering and Mechanics, Recovery Lead

Greg Z.

Freshman, Mechanical Engineering, Safety Officer

Vishnuu M.

Junior, Aerospace Engineering and Mechanics, Payload Lead

Hannah W.

Junior, Aerospace Engineering and Mechanics, Payload Team

Table of Contents

1 SUMMARY OF FLIGHT 4

1.1 Team Summary 4

1.2 Launch Vehicle Summary 4

1.3 Payload Summary 4

2 RESULTS 7

2.1 April 7th Crash 8

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2.2 Analysis of components 8

2.3 Summary of damage 9

3 ANALYSIS 9

3.1 Elimintaion of causes 9

3.2 Determined Failure modes 10

3.3 Root cause 10

4 CONCLUSION 11

4.1 Mitigation of future failure 11

4.2 Addendum for verification proceddure 11

4.3 Lessons Learned 12

4.5 Summary of Overall Experience 13

4.6 Education Engagment summary 13

4.7 Budget Summary 14

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1 Summary of Flight

1.1 Team Summary

Name: ‘Gopher Throttle Up’ Rocketry

School: University of Minnesota

107 Akerman Hall

110 Union St SE

Minneapolis, MN 55455

Chapter 1 Team Official: Dr. William Garrard

Team Mentor: Gary Stroick (TRA 5440 – Level 3 Certified)

1.2 Launch Vehicle Summary

Overall Length (in):

111 inches

Diameter: 6 inches Gross Weight: 524.8 oz Motor Selection: L1720 – WT Total Impulse: 3696 N-sec Recovery: Duel Deploy, ARRD

1.3 Payload Summary

Our scientific payload is a remote controlled rover Inquisitivity, based on the concept of

an extra-terrestrial space exploration vehicle and also on that of a rescue bot.

specifically, the payload is a ground deployed, 2 wheeled rover with onboard camera

and antenna. Once deployed, the rover transmits a live video feed to a ground station

where the rover can also receive commands to maneuver and investigate the terrain.

Overall Length (in):

14 inches

Diameter: 5.5 inches Gross Weight: 54 oz Power Plant: 2, 6.0 volt Servos Power Supply: NiMH 5 Cell, 6.0 volt

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Figure 1. Side and exploded view of vehicle as launched with components. The payload was not included for the test

launch.

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Figure 2. Diagram of launch trajectory with significant flight events observed.

A single event was reported at

after the craft had rolled over

apogee. Smoke could be seen

exiting the vehicle, but the

drogue chute did not deploy

Vehicle lifts off on

L1720 - WT

No further flight events

could be determined

from ground

observations

Ground impact

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Figure 3. Map of launch and crash site. Fortunately, the crash occurred in an empty

corn field where no persons were harmed or injured.

2 Results

Figure 4. Layout of wreckage components recovered. A reference of for this image can

be found in the back of this report.

500 m

Launch Site

Crash site

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2.1 April 7th Crash

During the first test launch of the vehicle, a malfunction within the drogue

deployment system prevented the drogue chute from deploying at apogee. Since the

main deployment was coupled with the drogue deployment, the vehicle did not

successful deploy any parachute upon reaching apogee.

The vehicle impacted the ground with sufficient speed to destroy all but a single

component from the flight. Because we were unable to recover any data from the

altimeters, the only results from the flight were eye witness accounts from the launch

team.

Figure 5. ARRD after being recovered from crash. The damage to it is superficial.

The ARRD design may make a good candidate for a black box.

2.2 Analysis of components

All structural components in the airframe performed as designed from launch to

apogee. At apogee when the ejection sequence was supposed to initiate, there was a

system failure which is unknown as to the origin due to the destruction of the altimeters.

With the best knowledge and observations available from video footage and

observations it is known at least one ejection charge deployed. However, because the

E-matches used to ignite the black powder during flight go off due to pressure as well as

electrical charge, the impact force which flattened the canisters could have also set off

the second charge making it impossible to determine the at what point that canister

fired.

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Figure 11. The canisters from the vehicle were found crushed after the crash,

making it impossible to determine which on fired at apogee.

2.3 Summary of damage

The damage inflicted upon the airframe was catastrophic. The airframe is

completely destroyed and all components in the crash, with the exception of the ARRD,

are not flight capable. For future flights, a completely new aircraft must be assembled.

Analysis will continue to find the cause of the failed separation, and shall be verified

though a final ground test that accurately simulates the final configuration on launch.

The payload was not aboard during the test flight, and a mass simulator was used

instead.

3 Analysis

3.1 Elimintaion of causes

From observation, it is quite clear that the drogue parachute failed to deploy from

the vehicle. The team began an investigation by identifying the key systems involved

with the deploying the parachute as well as systems who’s failure could have resulted in

a decrease in the pressure needed to deploy the drogue chute.

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3.2 Determined Failure modes

The systems built into the vehicle that can contribute to a separation failure are

summarized in the table below.

Table 1. Summary of components that could have contributed to a the failure

3.3 Root cause

At this time no single root cause for the failure of separation can be ascertained.

One charge was visually confirmed to fire so the cause for the lack of separation was

most likely a mechanical combination of several subsystems.

However, the systems that could have contributed to this have been identified are

ground testable, assuming the vehicle can be rebuilt accurately to its configuration

during the test flight.

One canister

fires

Separation Fails

System Significance Effect

Rail Buttons Does not provide an air tight seal

Gas form ejection can leak

Coupler Seal 1mm gap was observed between two tubes prior to launch

Vehicle is given a distance that could “jam” the components together

Black powder amount Was not test at final mass, only calibrated

Insufficient amount

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4 Conclusion

4.1 Mitigation of future failure

The ground tests conducted to verify that the recovery system was ready for

integration had been conducted with a sub assembled vehicle. This was done to meet

testing deadlines while other portions of the vehicle were under construction.

Although this tradecraft is recognized in high powered rocketry, the dynamics of

the chosen drogue eject system are highly experimental, and even though procedure for

adding the additional amount of black powder to calibrate for a fully weighted vehicle

was applied, its scaling may not be identical for the requirements of the experimental

channel design.

This, and the absence of the retractable rail buttons, compromised to accuracy of

the test, and more investigation must be placed in black powder amount if this

configuration is chosen again.

Lastly, the ground tests did not account for the compressive effects that occur

during launch. Future tests for all vehicles shall account for this factor. Thus, improper

management of the project has contributed to the failure and inability of the team to

meet deadlines.

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4.2 Addendum for verification proceddure

Since initial ground testing confirmed the functionality of all onboard systems, the

verification procedure must be modified to include ground testing of a fully configured

vehicle. Simply put, initial ground testing must be followed up with a final ground test

immediately prior to any flight to the upmost accuracy of real flight conditions.

This is the only method to verify vehicle funcitonality in the presence of complex

and experimental systems, and ensure mission confidence.

4.3 Lessons Learned

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A table of shortcomings and mitigation procedures for next year can be

found below

Shortcoming Mitigation Plan

Insufficient testing of exerimental design

Increase the amount and varity of ground tests. Account for all variebles, and construct test articles sooner

Lack of funds till late january Begin fundraising this summer and seek additional donors

Difficulty finding appropriate launch windows in later winter

Finish test vehicle early to take advantage of clearer early winter weather

Fluxating team composition compromissed quality of work

Build a larger team to reduce the hazards of lossing a team member

Ineffectiveness of systems integration meathods slowed progress

Steamline process to build and verify test components, reduce dependency of systems on eachother to start testing sooner. Form dedicated systems integration team

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4.5 Summary of Overall Experience

In many regards, the 2012 -2013 USLI competition was the first for the Univeristy

of Minnesota. This year brought new energy to project but without the guidence needed

to overcome new hurdles that had not been anticipated in the previous year. Many

ideas from the start of the project had to be removed due to their complexity, but the

process helped the team focus on their goals.

The team overcame many financial, technical, and personal crises to make it

where they did. Although the crash may seem to marginalize the accomplishments for

the year, the truth remains that the team has improved since last year, and is poised to

continue to improve.

Overall, the experience has enlighted everyone on the complexities and details

within various engineering disciplines. It has given us the chance to pursue our own

ideas through an emprical approach that solves problems and inspires others. We have

learned how to over come failure, and how to prevent failure in the future.

4.6 Education Engagment summary

We have already begun creating new networks between the University and the

local community. We plan on doing a variety of outreach projects at local area schools.

We also plan on gaining additional community and University support through these

outreach projects. We will be working with the Center for Compact and Efficient Fluid

Power (CCEFP), North Star STEM Alliance, and the Minnesota Space Grant

Consortium (MnSGC).

Events: - Straw rockets - Plastic cup air cannons - CD Mini Hovercrafts - Water hydraulic pet racers - Air pneumatic circuit kit - Water hydraulic excavator demonstrator

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- 1 foot tall rubber based, air propelled rocket - Large Hovercraft demonstrations - Angular Acceleration demonstrations - Parachute launchers - 4 inch water propelled plastic rockets

4.7 Budget Summary

This year, the team was able to secure $8,150 in funding. Approximately $1,600

was lost in all the destroyed components in our full scale rocket, as well as $300 from

our first half-scale test rocket, and another $500 was spent but not lost on our second

half-scale test rocket (more because the leftover materials from previous years were

used up in the first test rocket). Just over $450 was spent on necessary tools as well as

$300 on extra materials used in experimental tubing techniques, preliminary designs,

and currently shelved but usable left-over materials. We also have two leftover L1720-

WT motors valued at around $200 each that will be used in future projects. The funding

that went towards our payload was just over $1,200 and is reusable for following

projects as it was not involved in the crash.

Because of the catastrophic crash, we chose to send four members instead of

seven down to Alabama to participate in the Rocket Fair and other USLI events. This

choice cut our expenses from $1800 down to $700, because we were able to use the

smaller vehicle of a team member rather than renting a van, as well as only requiring

one hotel room.

Our team currently has $2600 leftover that will go towards projects planned for

this summer as well as help kick start next year’s USLI project.

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Reference for recovered components:

Airframe Tube Aft Bulkhead

Retainer Piece

Centering

Ring

Canisters

9 Volt

ARRD

AV Aft Bulkhead

AV Forward

Bulkhead

Nose cone

shoulder