The goal of maintaining a launch history is to keep a chronology of lessons learned from each launch, as well as documenting successes, failures, and keeping a log of last-minute fixes (which may need to get implemented into official checklists or may necessitate a change of design).

The individual launch pages should contain photos, description of off-nominal procedures (as well as the procedures followed during the launch, if possible), notable events, as well as lessons learned for the relevant sub-teams.

Post Launch Assessment Review Slides:

Minimum Diameter Rocket - Project MINDI

Table of Contents:

Abstract

Mindi is STAR’s first minimum diameter rocket, designed to be a one-semester project to optimize for apogee while practicing the necessary engineering techniques for the team’s future minimum-diameter projects, such as the lower stage of a future multi-stage rocket. The target apogee is 15,000 feet, and to this end the rocket is flying a K1103 Propellant X motor. Onboard electronics include an Altus Metrum TeleGPS for tracking purposes, 2 Eggtimer Apogee Deployment Controllers to deploy the accompanying Jolly Logic Chute Release, and 2 Mini WiFi Switches to arm the avionics from outside the rocket. The airframe consists of 54mm thin-walled fiberglass tubing, a 54TAC precision CNC-machined tail cone and an accompanying rail guide from the Wildman Mach 2 kit. The fins were cut from ⅛’’ fiberglass stock, secured to the rocket through a combination of JB Weld Steel and a robust fin glassing procedure, and manually airfoiled. Our electronics were mounted into a 3D-printed avionics bay, which was screwed onto the forward end of the motor retainer. This motor retainer, into which the motor’s forward closure was screwed, was epoxied into the airframe. An ⅛’’ aluminum annulus was epoxied into the airframe above the avionics bay, through which the assembly was inserted and screwed in, and an ⅛’’ aluminum bulkhead was screwed onto the annulus to close off the avionics section of our rocket. Mindi was designed to separate at apogee and fall freely until a height of 600ft, at which point the Jolly Logic Chute Release would deploy a 30’’ parachute. This deployment system was designed to expedite the physical recovery process for the rocket, as deploying a parachute at such a height would cause great drift. The duplicate electronics were intended for redundancy to ensure safe recovery.

Introduction

Team overview

Space Technologies and Rocketry (STAR) is affiliated with the University of California, Berkeley, and supported by the Associated Students of the University of California (ASUC), Boeing, Tameson, Procter & Gamble, Bay Area Circuits, Dassault Systems, Northrop Grumman, Technetics Group, Seamless Tanks, and Graphite Store. This project was a joint effort between members of our airframe and recovery subteams.

Airframe

Mindi was initially envisioned as an experimental airframe project. The airframe challenges in question are primarily twofold: 1) mounting and reinforcing the fins to support the rocket through its high-velocity flight, and 2) retaining the motor. A third challenge which became clear during the manufacturing process was inserting and securing components within the 54mm airframe.

To address the first point, we sought a way to ensure a rigorous mounting procedure for Mindi’s fins given the impossibility of traditional through-wall mounting. For phase one, we applied JB Weld Steel to the fin root chords and pressed them to the outer airframe. A 3D-printed jig was designed to ensure perpendicularity with the airframe, proper alignment and equal spacing. For phase two, we applied a 2-layer fiberglass cloth tip-to-tip layup with West Systems 207 as the resin and hardener of choice.

Motor retention proved easier than expected. We purchased a 54mm minimum-diameter motor retainer which screwed onto the motor’s forward closure, and then was installed by inserting the assembly into the airframe with JB Weld Steel applied in a ring at the desired location.

For the third challenge, a variety of jigs and special tools were designed and purchased to help us reach long distances down Mindi’s body tube. This included a pair of tongs, a specialty screwdriver, and various long, thin sticks.

Recovery

The recovery system on Mindi is fairly straightforward. However, our team has never worked with the Jolly Logic Chute Release before, so this was tested by our recovery subteam and redundancy was incorporated into our avionics system to ensure the intended operation. As the rocket was designed to separate at apogee and fall freely for around 14,000 feet, the parachute also had to be selected to be able to deploy at such speed and remain undamaged – the ramifications of this will be discussed in a later section. Black powder charges were used to separate the rocket at apogee, and controlled by the Eggtimer Apogee Deployment controllers.

Systems Architecture Overview

General Airframe

Since we knew our rocket would be going transonic during flight, we could not rely on our usual simulation software of choice (OpenRocket) and turned instead to engines which are particularly suited for simulating trans- and super-sonic flights. RasAERO II was the software we used to model our general airframe setup. The only involved parameters were the total weight of the rocket and motor, all external geometry (body tube, fins, and tail cone), basic recovery deployment altitudes, and the K1103X thrust curve. From this information we were able to generate altitude, drag, and stability plots, to name just a few. We mainly used this software for its apogee estimate, as well as to demonstrate the importance of surface finish on the rocket, as varying the “smoothness” parameter to increase roughness lead to an apogee loss of up to 3,000 feet. We addressed this by developing a robust procedure for our paint job. We also discovered that including the tail cone increases the apogee by up to 1,000 feet.

Body tube

As Mindi was intended as an experimental project, the diameter of the body tube was arbitrarily determined; choosing such a small diameter later posed some interesting engineering challenges. Due to the high forces experienced during flight, we knew that body tube materials such as blue tube would not be suitable for the vehicle, and turned instead to fiberglass. Although we originally planned to purchase fiberglass components from Apogee Rocketry, a contact of our team offered to sell us parts from his Mach 2 kit, and after conducting a cost comparison, we eagerly accepted, gaining in the process a filament-wound, thin-wall, 35-inch 54mm body tube. The main factor in the improved cost-benefit was that we were able to use the RMS 54/1706 motor casing on loan (granted no damage) rather than purchasing it for around $200.

We wanted our shear pins to be as small as possible, so that they would better conform to the rocket’s outer surface and not add tremendously to drag. We selected 2-56 nylon shear pins, since by using their reported maximum and minimum shear strengths in PSI we calculated a shear force range of 93-137 lbf for later use in black powder calculations. The PSI range for our shear pins fell well within the fiberglass tensile strength range of 45,000 - 50,000 PSI so we were confident that we could use 2-56 shear pins without damaging the rocket’s airframe. Three corresponding holes were drilled into the top of the body tube, halfway down the nose cone coupler, to secure these.

Two vent holes were drilled into our avionics section (discussed in Avionics, below) to allow the vehicle’s internal pressure to equalize with the external atmospheric pressure. Considering an atmospheric pressure of about 101.325 kPa at ground level and about 57.2 kPa at our target apogee of 15,000 feet, and combining this data with our body tube diameter of 54mm, or about 2 inches, we obtain an upwards force of about 80 lbf on our nose cone with no vent holes. This is not enough to shear the shear pins, but the primary purpose of our vent holes was to provide our altimeters with accurate enough static air pressure to effectively report altitude.

The rocket was recovered with no tube delamination or failure, which validated our design choices.

Nose cone

Our 13’’ fiberglass nose cone also came with the Mach 2 kit, and it featured an aluminum tip with an eye-bolt which we epoxied in with JB Weld Steel, and to which we then attached the shock cord.

Due to the nose cone and body tube being a part of Wildman’s Mach 2 kit, we felt confident making assumptions that these rocket components could handle Mach 2 speeds and the accompanying forces, so we focused more attention on the vehicle components which we were designing and manufacturing, which is what follows.

Fins

Our fins were water-jetted from ⅛’’ fiberglass. We determined the dimensions, such as root chord and tip chord length, based on what yielded a favorable stability (one-tenth of the length-to-diameter ratio, about 1.8 calibers) on the OpenRocket simulation software.

Fin dimensions

For the first step of securing the fins to the airframe, we designed a jig to support the fins throughout their root chord length, to ensure that they were perpendicular not only to the outside of the airframe tube, but also to the lower edge of the airframe itself. Additionally, this 3D-printed jig helped us ensure that each of the 3 fins was 120° from the next. After applying JB Weld Steel to the fin root chords and attaching them to the airframe under jig, we were able to reach into the jig’s slots to make fillets at the fin bases. In retrospect, the height of the jig should have been increased to allow our fillets to run the length of the fin root chords, but in order to stay on our timeline we did our best with the jig which was printed. CAD is available in the Appendix.

Fin jig on the rocket, pre-epoxy

For the second step, we glassed the fins. To this end, we sized 3 cuts of cloth for each pair of fins – two to cover the fillet areas, and one piece which extended from one tip chord to the other, running along the area of each fin and the section of body tube separating them. We lay down the corresponding sizes of fiberglass cloth with 45° translation between layers, where each layer was also separated by a thin layer of West Systems 207 Resin and Hardener, brushed on with a paintbrush. This was our first time performing this procedure on a rocket and we practiced extensively before glassing Mindi. Considering that the fins only showed some paint damage post-launch, we consider this effort successful.

After glassing, the excess cloth was removed with a dremel. We then manually airfoiled the fins with an orbital sander, ⅜’’ from the fin edges, leaving 1/16’’ of fin thickness to ensure stability. This proved to be a difficult task, since our fins are so small, and we used a dremel in conjunction with sandpaper to ensure a smooth finish. They are far from professional airfoils but we decided to include them to further increase apogee and reduce drag on the fin section of the vehicle.

Post-airfoiling with West Systems applied above fins to patch glassing

Additionally, we used the fin simulation software AeroFinSim to ensure that our fin design was robust enough to handle the forces which it would be subjected to during flight.

AeroFinSim results

We aimed for our simulated velocity not to exceed either the divergence or flutter velocities, (3098.59 ft/s and 4215.16 ft/s, respectively) both of which would indicate fin instability. From our RasAERO II simulations, the maximum in-flight velocity was 2200 ft/s, which is comfortably under the two critical velocities.

Motor hardware

We used the RMS 54/1706 casing in conjunction with our K1103X motor. Since we did not use the motor’s ejection charge to deploy a parachute, we had to purchase a plugged forward closure, which featured a threaded hole compatible with our motor retainer. On the aft end, our tail cone acted as an aft closure. Additionally, we initially planned to use the aluminum seal disk included with the motor casing, but upon research we discovered that the high burn temperature of the K1103X motor would damage this disk, and we sought a stainless steel alternative instead.

To assemble the motor, we first cleaned the inside of the casing with acetone and water. We then sanded the casing interior and the outsides of the 4 grains to create more surface area for our glue to bond to. As per recommendation from Aerotech, we used Elmer’s Glue-All Max. We then applied lube to the O-rings for the tail cone and forward closure and let the grains set.

A cleaning and inspection post-launch confirmed that the casing and hardware incurred no damage.

Parachute

Our recovery team selected a 30’’ octagon-shaped nylon parachute with a shroud line length of 30’’. In retrospect, after analyzing flight data from our TeleGPS, Mindi was falling at roughly 100 ft/s at the time of chute deployment at 600 feet from the ground, and this parachute was not rated to handle such forces. In fact, selecting a parachute to withstand such a high snatch force is near impossible and we should have re-evaluated our drogueless design in light of this. This will be discussed more in the Lessons Learned section.

Avionics

Mindi flew one Altus Metrum TeleGPS, 2 Eggtimer Apogee Deployment Controllers, and 2 Mini WiFi Switches. These were selected mainly due to their size, which made them the simplest recovery electronics available. Our avionics bay design took several iterations to perfect, and we settled on essentially mounting the boards and the batteries required to power them to a long block with a 10-24 threaded rod on the bottom to screw into the motor retainer, and a handle at the top to aid in the insertion process. See Appendix for the CAD model.

Paint

The paint job for this rocket proved non-trivial. Ensuring a smooth finish after all of our hard work was essential, so we developed a schedule to apply primer, paint, and then gloss to the rocket in several coats, with the appropriate amounts of time between each to allow for complete curing.

Mission Concept of Operations Overview

1. Design & Manufacturing

2. 1. Due to the small diameter of the rocket, the airframe tube also serves as the motor mount tube. This eliminates the need for centering rings.

   2. Attaching fins will be different from other rockets built in the past

   3. 1. Will need to be attached to the tube since there will not be slots for them

      2. 1. JB Weld on the root, then make fillets with 30 minute epoxy reinforced with carbon fiber threads. Fin glassing will be done for maximum support.

3. Pre-launch Preparation and Arming:

4. 1. Vehicle is prepared for flight on or before the day of launch. Preparations end with the arming of energetic systems while the rocket is on the pad.

   2. Ground Test

   3. 1. Recovery systems are tested for functionality. Minor modifications for testing are allowed.

   4. Flight Preparation

   5. 1. Recovery systems are prepared in a flight configuration.

   6. Arming

   7. 1. Vehicle is loaded onto the rail and armed for flight.

5. Ignition and Boost:

6. 1. The motor is ignited and the vehicle exits the launch rail with an appropriate velocity. It later enters a powered, stable flight.

7. Coast:

8. 1. The motor burns out after 1.6 seconds and the rocket continues an unpowered, stable flight.

9. Recovery:

10. 1. Apogee

    2. 1. Vehicle separates.

    3. Descent and Chute Deployment

    4. 1. Jolly Logic Chute Release deploys parachute at 600ft.

    5. Landing

    6. 1. The vehicle descends while drifting an acceptable range for the launch site. It lands with an acceptable amount of kinetic energy. An additional parachute may be deployed to meet drift and kinetic energy requirements.

       2. 1. Drift radius must be less than 2500 ft in 20 mph wind.

          2. Each component must not land with greater than 75 ft-lbs of kinetic energy.

    7. Tracking

    8. 1. Vehicle is located and recovered

Conclusion and Lessons Learned

Designing, building and launching Mindi proved to be a wonderful learning experience for our team.

Design lessons

As our design process happened over the summer, there were some choices that were made and then never revisited during the school year; we simply operated as if these were absolutes. For example, selecting a 54mm diameter was arbitrary at first but not questioned during our design reviews. In the end, this proved useful because our members, particularly new members, were able to confront and think their way around the challenges of securing components into such a thin tube, but we could have avoided this at least in part by selecting, for example, a 98mm body tube. Additionally, after we chose to use the Jolly Logic Chute Release, we should have done the necessary calculations to discover that the parachute would end up deploying at an unsuitably high speed. Instead, we mistakenly used our numbers for apogee deployment. The reasons for never revisiting this are more complex, though, and will be discussed in the Project management lessons section below.

Manufacturing lessons

Many of these issues could have been resolved had we had a more lenient timeline, but since we aimed to launch this rocket within a semester, we were often forced to work with what we had rather than iterating. For example, our fin jig for the first step of attaching fins was a bit too short, meaning that our fillets did not fully extend to the tops of the fin root chords. This was somewhat remedied by post-processing the layups, but having that thick, smooth fillet as a base would have helped us lay down fiberglass cloth and be more secure that bubbles would not arise during the glassing process.

On the day of launch, we discovered that our simulated center of pressure and measured center of gravity were about two times as close as desired (2 inches, which, divided by the rocket diameter, yields a starting stability of 1.0 calibers – too low). To mitigate this, we were forced to create a last-minute ballast of 160 grams, consisting of sand in a Ziploc bag, and secure this to the parachute shock cord. We calculated the appropriate weight using center-of-mass equations. This increased our measured on-the-rail stability to 1.75 and proved effective, but in the future the center of pressure and gravity should be marked during integration.

Left: ballast, Right: center of mass calculations on day of launch

Additionally, we extended our glassing cloth too far outside the fin leading edges, causing unfavorable geometry above the fins which had to then be sanded down and patched up with epoxy. This was due to a miscommunication and we will adjust our procedures accordingly.

Excess fin glassing cloth

Project management lessons

The main lesson we learned from Mindi was the importance of communication. The cooperation of the recovery and airframe subteams on this project in particular was imperative and fell short at some times, as the project was headed by two airframe members. In the future, having one airframe lead and one recovery lead co-manage the project would be more beneficial. Additionally, having joint planning meetings throughout the course of the project and sharing a timeline, which we only did in the last month of the project, would be valuable from the beginning.

In general, though, all of our team members contributed their ideas, skills, and enthusiasm to the project. We are proud of what we were able to accomplish and that so many new members were exposed to the design, manufacturing, and launch process, and we look forward to what we can accomplish together next.

Appendices

System weights and measurements

Airframe length: 45.5 inches

Airframe diameter: 54mm, ~2.126 inches

Fin span: 6.236 inches

Mass with motor: 7.2 pounds

Number of stages: 1

Propulsion type: Solid

Off-the-rail velocity: 80 ft/s

Target apogee: 15,000 ft

Projected apogee: 13,975ft (OpenRocket), 18,726ft (RASAero II)

Stability: 1.75 cal

Maximum velocity: 2,200 ft/s (RASAero II)

Preliminary FMEA

CAD

Avionics bay

Fin jig

Founding - 2016 Spring

STAR was founded in Spring 2016 by a small group of students who were interested in model rocketry. The team's core activities consisted of building commercial-off-the-shelf model rockets and launching them from Martin Luther King Jr. Civic Park. Additionally, a few members were working toward National Association of Rocketry Level 1 certifications. By the end of this semester, there were around 10 members.

NASA Student Launch - Fall 2016 to Spring 2017

Initial activities in the 2016-2017 School Year involved recruitment at the College of Engineering Activities Fair during the first week of school. After recruitment, a decision was made by the whole team (around 25 people at this point) to participate in NASA Student Launch.

Rapid Unscheduled Disassembly of Ursa Major. This is a skeleton article.

This was the first flight of Ursa Minor. This is a skeleton article.

Ursa Minor flew on a J800 motor.

Disclaimer: These notes should be verified and compiled into a more permanent document, maybe a spreadsheet. This information is routinely lost to the sands of time each time we compile it..

Ursa Minor

• 4” diameter

• Some reference dimensions exist on GitBook

• NASA Student Launch 2016-2017 Sub-Scale

• Blue Tube airframe material

Ursa Major

• 6” diameter

• 75mm motor mount

• Single-side dual deploy with independently recovered payload section

• ORK exists, reference dimensions appear to match manual measurements.

• NASA Student Launch 2016-2017 Full-Scale (competition vehicle)

• Blue Tube airframe material

Sub-Arktos

• Single-side dual deploy

• Blue Tube airframe material

• 2.6” booster, 4” upper section

• Fiberglassed printed 2.6” -> 4” transition

• Flown 2019-04-20 successfully

• ORK exists and is generally known to be correct.

• NASA SL 2017-2018 Sub-Scale

Arktos

• 54mm motor mount, functional 4” booster

• Blue Tube airframe material

• 4” booster, 6” upper section

• No undamaged 4” -> 6” printed transition parts in stock

• ORK exists and is generally known to be correct.

• Have had several anomalies with this design and no successful launches with recovery

• NASA SL 2017-2018 Full-Scale

Spectre

• Design only, never made it to build phase

• Overly ambitious two-stage COTS solid + SRAD liquid engine with complex stage separation mechanism

• Started design for IREC 2017-2018, entered in IREC 2018-2019, did not participate (instead launched Sub-Arktos again that year). Project permanently canceled while liquid engine tech is matured.

AirBears

• 4” diameter

• 75mm motor mount

• Damage to booster tube: 6” long tear from shear pin, probably

• Functional upper section

• ORK exists and is definitely correct

• Flown twice

• Test vehicle; flown with payloads and intended to fly with CAS, rip CAS

• Less documentation than competition vehicles as focus was on rapid development

Bear Force One

• 6” diameter

• 98mm motor mount

• Fiberglass airframe material

• Completely undamaged except its nose cone tip needs epoxy

• The payload tube has DAVE ejection hardware epoxied in it

• ORK exists and is definitely correct

• IREC 2019-2020 entry, postponed to 2020-2021

• Flew completely successfully (except for the IRIS/Muons payload and the MFC payload)

• Only rocket to have onboard cameras

• Reached 10,128ft flying on an Aerotech M2500 motor

• Intended to refly as the test vehicle for DAVE, rip DAVE

Pinkbeary

• 5.5” diameter

• The club’s first two stage rocket, intended as test vehicle for staging

• 75mm motor mount with K1000 staging to 54mm motor mount with J800

• Bluetube airframe material

• ORK exists and is definitely correct

• Flown twice, exactly one year apart

• Successfully staged both flights

• RUD of 2nd stage on first flight ~1s after secondary ignition, interstage not recovered

• Second flight testing improved staging mechanism, SS-DD recovery on the first stage, and custom avionics, no motor in second stage to save money

• Multiple recovery failures due to human error on second flight leading to critical damage to the adjustable ballast section at bulkhead, multiple zippering areas due to both sock cord and shear pins, not flyable

• Reached ~2200-2300ft both times

MINDI

• 2” diameter (yes, really)

• The club’s first minimum diameter rocket

• 54mm “motor mount” since minimum diameter, flying an Aerotech K1103 motor

• Fiberglass airframe material

• ORK exists and is definitely correct

• Flown once to 14.3kft, current Berkeley altitude record-holder

• Mysterious recovery failure(?) with drogue-less descent followed by main deployed with Jolly Logic Chute Release. Eye of parachute ripped by parachute but still landed 2ft from rocket. Body undamaged, nose cone “intact” but sheared, not flyable

CalVisitor

• 6” diameter

• 98mm motor mount flying Aerotech M1939 motor

• Fiberglass airframe material

• ORK exists and is definitely correct

• Entry for IREC 2022-2023, originally planned for IREC 2021-2022 under the name “HighBearNation”

• 4th place in the apogee competition, reached 10023ft, 23ft off of perfect

• Recovery deployed successfully but the booster section completely sheared off the rocket upon main deployment at the airbrakes fin holes. Then dragged ~5 miles across the desert in the wind before finally being recovered 22hrs after landing. No section survived this event in a flyable condition

• Probably the closest the club will ever get to the target apogee in IREC

Alula

• In development, scheduled to fly January 21st, 2024

• 6” diameter

• Ethanol + LOx biprop blowdown liquid engine

• Test vehicle, the club’s first liquid engine-powered vehicle

• ORK exists (mostly) and will definitely be correct

• Entry for FAR’s Dollar-Per-Foot competition

This was the first flight of Ursa Major. This is a skeleton article.

We flew successfully at Huntsville, AL. This is a skeleton page.

Ursa Major was flown on an L1150 motor, with hardware borrowed from David.

Members In Attendance

Airframe

• Megan Joseph (MINDI Project Manager)

• Anjana Saravanan

• Anant Ayyar

Recovery

• Cassidy Powers (LEAD)

• Jonah Henry (SSEP Project Manager)

• Max Gu

• Shadi Hassani

• Andrew Zhu

Systems

• Cassiopeia Young (LEAD, Recovery)

PVP

• Aarabhi Achanta (President)

Media

• Saranyu Nel (LEAD)

• Jingyuan Chen (Prospective)

September 16

Evening Departure Logistics

• Launch logistics were organized a week in advance with a spreadsheet listing cars and drivers.

• No one shuffled between cars.

• Cars left around 4:30 PM on 16 Sep. Two left from Hearst Mining Circle. One directly went to pick members up and then went to buy groceries for the launch, leaving Berkeley around 5:30 PM.

  • In the future, we should purchase groceries ahead of time to avoid getting stuck in rush hour traffic.

• Stop made at Denny's, In&Out for dinner & to allow the late-departing car to catch up.

• Arrived at Motel 6 in Mojave, CA at 12:45 AM on 17 Sep.

  • In the future, recommend departing earlier in the day (depending on availability) and stopping for less time in order to arrive earlier to allow for more time to rest.

September 17

• Departed from Motel 6 at 7:30 AM.

• Arrived at FAR at 8:30 AM.

• Began integration immediately. Integration completed by 11:30 AM but launch was delayed to allow for Michael Karish (former Recovery Lead and SSEP PM) to join a virtual call to watch launch.

• FAR officials did not hold safety talk, nor did they require a L2 cert.

Ground Test

• Not held due to extensive experience and testing in stage separation and parachute deployment.

• Ground tests may not be held during launches in the future. TBD by Recovery.

Launch

• Pinkbeary placed on launch rail and armed at 12:45 PM.

• Initial launch attempt scrubbed due to failed lower-stage motor igniter.

• Pinkbeary successfully launched at 1:46 PM after FAR officials provided STAR with a new custom-made motor igniter.

Flight

Several failed launches from earlier in the season left us with no choice but to drive down to Arizona and launch one last time and pray it would be successful.

For a ground-test, we drove over to David's house and performed it in his backyard as there was no other location available and no time to wait. Preparations went well however, the e-matches were likely placed too close to the side of the tube for parachute ejection leading to a smoking hole in the side of the airframe.

The hole was patched up with epoxy as we were able to locate the blue-tube fragment. Gorilla tape was also used to ensure the fragment would not be a significant weak point during the coming launch. These were all just "temporary" measures for the trip. With the mostly successful ground ejection test complete, we got 4 vials of 5 gram black powder and some shear pins we continued our drive through the night to reach the Arizona launch site.

Our preparations for launch at Arizona were expedited by the large amount of recovery sub team members and we were ready to launch before noon.

Another successful ground ejection test was performed at the Arizona launch site and the rocket was completely repacked and ready for an early launch so we could start the long drive back early.

However, around noon, winds began to pick up. There was sand flying everywhere blinding us and also accumulating within the rocket. Completing all the assembly, we decided to load the rocket into the van and relocating it at least temporarily into a nearby bunker and wait for the winds to die down before attempting to launch.

Around 2 pm, after almost losing hope there would be a launch at all, the winds died down enough for us to attempt a launch. All systems looked good as the rocket was loaded onto the launch rail. All the switches were turned on and everything was looking up.

The launch looked good for the first 400 meters before starting to spiral and cone. The nosecone appeared to pop off and the rest of the rocket continued to shoot up another few hundred meters. We did not reach the goal due to the additional drag from the missing nosecone. Thus, the apogee was less than expected but all recovery procedures went off perfectly and the remaining portion of the rocket was recovered perfectly without reaching the 5280 ft target apogee. The team went on a search for the rover that appeared to have dropped out of the nosecone from several hundred meters up and crashed to the ground. Most pieces were eventually recovered as the winds had died down dramatically so none of the pieces flew very far into the desert.

We are still unsure of what exactly happened to the rocket to cause such catastrophic damage but here are a few observations:

• 2 of the shear pins for payload were still in the airframe, the last one appeared to have ripped through the airframe.

• Scissor lift was deployed but there is no way of confirming when it deployed, whether it was before or after separation.

• Rover completely smashed to smithereens likely due to its several hundred meter fall.

• Recovery was successful without full apogee and no rushed environment.

• Radio failed to connect on the launch rail once again, investigating whether it has to do with rail interference.

• People at Arizona launch site said to look into coning, not sure if that is the full reason though.

Photos: Cheljea Jang

After the rapid unscheduled disassembly of Ursa Major, we had 2 weeks to fix the broken parts of Ursa Major, build a new payload, and fly the rocket in order to qualify us for the final flight in Alabama. With the Snow Ranch launch site rained out, the closest launch site was the Mojave Desert Advanced Rocketry Society site near Edwards AFB in southern California.

A big thanks to everyone on the 2016-2017 team who were able to make this launch happen. Special shout-out to Adam's parents, who hosted us overnight during our rushed final preparations, and to the MDARS folks for staying at the site until we were ready to launch.

Photos: Brunston Poon

The first flight of AirBears constituted the largest launch we have had to date in terms of attendance, with a total of 47 members. It was also our first fully nominal launch in over a year (Sub-Arktos was successfully flown and recovered earlier in the year, but with off-nominal parachute deployment).

Morning Logistics

Launch logistics were well-organized with the a spreadsheet with assigned drivers and seats. Moving forward however, we should have contingencies in place for when drivers do not show up/wake up on time for launches. We left around 5:20 a.m. from Etcheverry Hall (nominal time to meet was set at 4:40 a.m.); in the future, we should pack the day before and leave from the Hearst Memorial Mining Circle to minimize disruption to residents.

We arrived at TCC around 9 a.m. and were able to get fully set up by 10 a.m. It is recommended that at least one car arrive before 9 a.m., as attendance at the flyers meeting is required, and setup help is much appreciated.

Ground Test

Recovery ground test originally used wire crimps but because the crimps were finicky and hard to get on, they were abandoned later. Ground test consisted of the use of two one-gram black powder charges. The drogue chute deployed very well, however, the main chute tube had separation of only a few inches so we sized up to two-gram black powder charges for both sides and performed a second ground test. This one went well, only testing the main parachute side with complete separation.

Ground test 2 video:

It must be noted that the scale we brought to use was not working well and failed to measure therefore black powder charges were measured based on volume of vial and estimated density (found online) and not actual weight. We will add a hundredth-gram precision or better scale to our checklists.

Payload and Avionics

The payloads flown were an SRAD electronic sensing package named IRIS (Iris Records Information via Sensors) and Muons, a cosmic ray detector. In addition to the Payload subteam's payloads, the Avionics subteam flew the avionics sled previously flown on Sub-Arktos on 2019-04-20.

While the avionics sled integrated smoothly, the payload stack was difficult to integrate, despite having done so successfully at integration a week earlier. As a result, the IRIS payload was subject to an unexpected loss of power during assembly. While the power was reconnected, the payload was never re-initialized, a manual step required to begin recording. As a result, IRIS did not record data for this flight. We are exploring software changes and hardware changes to make this impossible, as well as updating procedures.

Final Assembly and Arming

Once the payload, avionics, and sims altimeters were all mounted into the payload section, the many sections of the rocket were screwed together with pan head sheet metal screws and shear pins at separable interfaces. Everything closed properly but the main parachute was a bit tight.

Pictures were taken both before going out to the launchpad and on the launchpad. Once the pictures were taken, all non-essential personnel were asked to leave the launchpad and the rocket was loaded onto the launch rail. Note we did not bring Teflon lubricant to the pad as checklists instructed; it was judged this was an acceptable departure from procedure. It was exceedingly difficult to insert the retaining pin to hold the launch rail in place; recommend bringing a hammer.

With the rocket in place, the igniter was inserted according to procedure and successfully checked for continuity. Recovery altimeters were nominal and the Simulations subteam altimeter was instructed to start recording via Bluetooth.

Flight and Recovery

AirBears flew nominally, going up to 4509 ft apogee. This was incredibly close to the projected apogee of 4500 ft. The two recovery altimeters recorded 4508 and 4509 ft respectively. Drogue deployed at apogee and the main parachute deployed at 800 ft. There was very little wind thus the parachute drifted very close to the original launch location around 100 meters away. All black powder was fully burned off.

[payload and avionics]

Slight burns were noticed on all of the parachutes likely because of poor parachute bag sizing and the black powder charges ended up being quite large.