Tuskegee University

Cansat 2008

After – Action Report and Analysis

Overview of After-Action Report Attending Members Design Overview Data as recorded by ground station Results of flight (success, failure, and

omissions) Failure mode analysis Lessons learned Preparations for next competition

Attending Members

Software Lead: Christopher Coleman

Hardware Lead: Brandon Williams

Advisor: Eldon Triggs

Design Overview

2.8 inch diameter by 11 inch length planetary exploration payload

Parachute to surface and record altitude during entire flight

Transmit data to ground station during flight Land upright and detach parachute prior to

landing

Design Overview

Use of COTS hardware to collect data and transmit to ground station (ARTS2 altimeter and TX-900G transmitter/GPS)

Use hotwire connected to pyros to cut parachute loose

Use LDM (Lawn Dart Method) to land upright Use 9.6V battery to power all functions

Ground station data collection Heavy emphasis on collection of altitude

data1. Average descent rate was 14.1 feet/sec or 4.3

meters/sec

2. Max barometric altitude was 4852 feet / 1330 ft AGL

3. Max acceleration was 43.37 meters/sec^2

Results of Flight

Tuskegee University’s Cansat successfully flew on June 14th, 2008

First Cansat competition for Tuskegee

Some objectives/requirements met, some were not

Objectives achieved

Measurement of altitude and transmit to ground station. Good link with ARTS2 altimeter and TX-900G

transmitter throughout duration of flight (maximum signal strength)

Storage of data on ground station and flight computer successful

Objectives achieved

Proper parachute deployment

Parachute packing was correct and allowed proper deployment

Parachute deployed and slowed the Cansat to 4.3 m/s average

Objectives Missed

Landing upright Due to weight restrictions, landing legs were not

installed. Cansat impacted hard soil and was not able to

use landing pegs as LDM (Lawn Dart Method) Center of gravity higher than expected (roughly

centerline of spacecraft instead of low COG)

Objectives Missed

Parachute separation Ultimate altitude not determined correctly prior to

launch. As a consequence, pyros did not fire and cut

parachute cord. Method of parachute detachment outlined in PDR

and CDR was not able to be used due to weight concerns

Bonus Objectives Omitted

Due to weight issues, the vacuum motor, parachute release motor, stepper motor/drill, and temperature probe were omitted

Battery and component weights created issues that prevented attempting any bonus points

Failure Mode and Effect Analysis Anticipated failure modes based on severity1. Parachute deployment failure

Catastrophic failure (complete destruction of system, medium possibility)

2. Power system failure (battery disconnect/premature drain) Mission failure (not catastrophic, but part of basic requirements, medium

possibility)

3. Data downlink failure/transmission Mission failure (not catastrophic, but part of basic requirements, medium

possibility)

4. Parachute not detaching Mission failure (not catastrophic, but part of basic requirements, high possibility)

5. Not landing upright Mission failure (not catastrophic, but part of basic requirements, high possibility)

Failure Mode and Effect Analysis Actual failure modes based on severity1. Parachute deployment failure

Did not occur (successful)

2. Power system failure (battery disconnect/premature drain) Did not occur (successful)

3. Data downlink failure/transmission Did not occur (successful)

4. Parachute not detaching Mission failure ( failure occurred)

5. Not landing upright Mission failure ( failure occurred)

Failure analysis

Parachute detachment failure1. Pyro switch did not activate due to failure to

attain anticipated altitude (wind restrictions)

2. Pyro switch was calibrated on descent from apogee as well as time (not enough altitude or time)

3. Due to weight restrictions, the ultrasonic rangefinder was omitted and the process of parachute detachment was altered

Failure analysis

Cansat not landing upright1. Weight restrictions prevented landing legs from

being added

2. LDM (lawn Dart Method) was used, but the compacted soil prevented the pegs from penetrating the ground sufficiently (Cansat bounced rather than sticking)

3. Also, failure of parachute detachment mechanism caused the Cansat to be drug 1-2 feet AFTER landing

Lessons learned (generic)

Battery/Power source1. Battery did not fail, however last minute changes

increased the mass of the battery.

2. A larger current was needed to fire the pyro and maintain good downlink

3. Battery sizing needs to be more of a focus in the initial stages

4. Back up batteries on hand

Lessons learned (generic)

Structure1. Structure was satisfactory, but needed minor

modifications

2. Finite Element modeling of structure to properly reduce unnecessary mass

3. Consider alternative materials to reduce mass and increase durability

Lessons learned (generic)

Electronics1. Simplify wiring to reduce mass and possibility of

broken connections due to launch / MECO / Parachute deployment

2. Use of microprocessors to increase capability and reduce mass

3. Move from COTS to hand built parts to tailor functions to specific tasks/objectives

Lessons learned (specific)

Defining vertical landing. Some orientations were on the long axis instead of the circular diameter

Use of e-matches for pyros instead of high resistance / small diameter wire (used rocket igniters) as the wire was an abject failure.

Calibration of ARTS2 flight computer to provide more accurate data (i.e. redefine “up” and “down”

Lessons learned (specific)

Budget1. Funding: secure sources and commitments and

obtain funds EARLY

2. Find outside sources in the commercial community as well as academic

3. Use funding WISELY!

Lessons learned (specific)

Team organization1. Find members from other fields (electrical,

mechanical, etc) and recruit them. This year was aerospace engineering only.

2. Give members tasks based on their individual strengths and fields of study

3. Make team meeting regular and give specific outcomes for each meeting

Questions?