Project HEIDI

Spaceport America Cup 2019 – Project HEIDI

In September 2018 the second sounding rocket project of ARIS – Project HEIDI launched their journey towards Spaceport America Cup 2019. Together, 30 students from ETH Zurich, HSLU and ZHAW aimed to build a launch vehicle that can reach exactly 10’000 ft while carrying a payload of 4 kg. Additionally, a highly reliable recovery system should guarantee reusability.

On the morning of the launch, the team was greeted by favourable wind conditions. With the whole team waiting anxiously, the rocket was installed on the launch pad, and the launch button was pressed. Subsequently, a stunningly beautiful flight presented itself to the spectators. After lift-off, HEIDI flew on an unperturbed, straight flight path to apogee, after which the rocket separated, and the drogue parachute deployed. Close to the ground the main parachute then deployed as expected, and the rocket could be recovered without any damage to non-replenishable parts.

From on-board flight computer read-outs after the launch, the apogee was obtained – 9298 ft or 2834 m. The reason for this shortcoming was a combination of mass added to the rocket for increased safety and an underperforming motor burn. Accordingly, the team entered the award ceremony with mixed feelings and expectations.

Nevertheless, the hard work paid off. Project HEIDI reached 1010 points out of 1000 (bonus points for early launch and payload form-factor), scored second out of 46 teams in its category and fourth place out of 122 competing teams overall. Additionally, Team HEIDI’s effort to put safety in the middle of their operations was recognized with an honourable mention for safety.

Second participation. Second place.

Rocket engineering into the next round

Building upon the lessons learned from project TELL, team HEIDI aimed to increase the reliability of ARIS’ sounding rockets and strived for an award-winning system.

With project HEIDI, ARIS – in the second year of its existence – competed for the second time at the Spaceport America Cup in New Mexico and made the second place in its category of 10’000ft and commercial-off-the-shelf solid motors with a nominal flight. Project HEIDI was a full success.

To increase reliability and maximize the scoring

In the first phase of the project, the team combining ten different nationalities and eight fields of study concentrated on finding the most promising concepts and designing the system. With the help of a review board consisting of experts from academia and industry, the best concepts were evaluated in a preliminary design review (PDR) in October 2018, and critical design input was gathered in a critical design review (CDR) in November 2018. Both reviews were conducted in cooperation with the EPFL Rocket Team. The focus during this phase laid on building upon the knowledge from TELL and focusing on maximum reliability.

Reliability

Critical components were analyzed, and strategies to reduce specific risks implemented in this year’s design. Testing efforts were increased up to a maiden flight before the competition.

Pretdictability

To achieve a stable and precise trajectory, the rocket’s structure was tuned for dynamic stability. The rockets shape was optimized aerodynamically to reduce drag and increase efficiency.

Improved control

To better control the final altitude of the rocket and reach 10’000ft as precisely as possible, the airbrake mechanism was redesigned and aerodynamically improved.

Advanced payload interface

HEIDI enables to integrate up to three experiments at the same time and exchange these payloads within less than two minutes. The standardized interface structures simplify the process.

Second place, honorable mention for safety

The special focus on safety during the whole period of the project was not only leading to no incidents whatsoever but also was rewarded with an honorable mention at the spaceport cup.

The Rocket HEIDI

A sounding rocket specially developed to reach 10’000 ft above ground transporting a payload of 8.8 lbs.

Lift-off weight

Length

Diameter

Peak thrust

Total impulse

 Payload experiments

Subsystems

Every single system is specifically developed and tuned for maximum reliability and performance.

Solid motor

When reaching its peak thrust of 3400N, the commercially available solid rocket motor accelerates the system with 10 g to transonic velocities of up to 670 mph. Like the space shuttle boosters, it burns an ammonium perchlorate based solid propellant.

Airframe

The airframe is lightweight, yet sturdy enough to handle the high accelerations during the flight. This is achieved by using fibre composites for the fairings and nose cone as well as aerospace grade aluminium for the bulkheads and other interface structures.

Payload

The system carries three scientific experiments massing to 8.8 lbs distributed over five CubeSat units. A miniature microscope visualized biological cells during flight, a multitude of accelerometers estimate velocity and position of the system with high precision and electric energy is harvested from the system’s vibrations in flight.

Recovery system

Redundant, commercially available recovery electronics provide firing signals for a timely deployment of rocket separation, main parachute and drogue parachute. This dual event system ensures minimal drift from the launch pad. Here, the drogue parachute stabilises the descend after apogee while the main parachute, deploying at 700 ft AGL, slows the rocket to a safe touch down speed.

Separation mechanism

After reaching apogee, a separation of the rocket by C02 charges provides access to the parachute bay. Before that, the launcher is held together by shear pins proven in extensive ground testing as well as in flight.

Airbrake and control

The wind tunnel tested air brakes together with a highly sophisticated, student-developed control algorithm ensures that the system reaches the 10’000 ft apogee to very high precision.

Highly integrated electronics hardware

The active altitude control system of HEIDI is controlled using multiple sensors and significant computational power.

The team

Together, 30 students from 10 different fields of study combining 8 nationalities challenged universities from all over the world to reach the second place at Spaceport America Cup 2019. Photo credits: ESRA

A focus on reliability

Team HEIDI focused on increasing the reliability of the whole system during development. Critical components were analyzed, and subsystem testing increased.

HEIDI’s validation & verification principles

In project HEIDI, we followed a three-step plan to ensure reliability in all our systems as well as in the fully integrated launch vehicle.

1

Critical Components

Thorough FE-Analysis of structurally critical parts and early testing of mission-critical components

2

Subsystems

Parachute drop test and wind-tunnel characterization

3

Full System

Assembly & operations trainings and two full system launches to reduced altitude: one success, one fail.

Critical component testing and analysis

Finite Element Analysis of critical structural components

To ensure a safe flight of HEIDI, Finite Element Analysis has been performed on all critical load-bearing components. This helped us during the design to improve and optimize all the parts to gain performance and lose weight.

Shear pin testing

One of the most critical parts to design were the shear pins. These needed to be sized perfectly such that they can withstand the forces acting due to air brake deployment. However, they need to break when the CO2 is deployed in order to allow for the parachute release. A lot of testing has been performed on these components. Gaining insights with universal testing machines to verify calculations and a multitude of ejection tests.

Aerodynamic analysis of the airbrake system

The air brakes from project TELL were analyzed carefully in order to find room for improvement. We were able to optimize two parameters at the same time: we were able to create more drag with a bigger plate as well as the addition of a lip. At the same time, this lip helped us reducing the wake behind the airbrakes which resulted in a more laminar airflow around the fins leading to a more stable flight. These results could be backed up with our wind tunnel test performed in march 2019.

Subsystem Testing

Droptest: Re-assure the reliable function

In order to validate our preliminary test, we were able to perform a drop test form 70 meters above ground in spring, using a ropeway in the heart of Switzerland. Thereby we could see that our chosen recovery concept worked fine and we could proceed towards a test under flight conditions in the upcoming weeks.

Windtunnel Test: identify and verify the aerodynamic parameters

This test was a major milestone for the team since it was able to characterize our rocket at different stages during flight as well as validate our computational fluid dynamic simulations performed over the past months. Testing at angles of up to 9 degrees and extracting the air brakes during these tests gave us lots of data to analyze and improve our simulations for higher wind speeds.

Full System Testing

Full system flights to reduced altitudes in Switzerland

After successfully passing the previous testing stages, we were cleared for a maiden flight of HEIDI end of march 2019. A successful flight was the result with HEIDI reaching an altitude of more than 1000 m above ground level. With a speed of more than 300km/h and a peak acceleration of 6g, we were ready for the final push towards the Spaceport America Cup.

Assembly and operations dry runs

After our full system flight, we were not only optimizing our system, but also our procedures to have a fast assembly at the competition. This was done by multiple trainings at external facilities in order to mimic not only assembly but also packing and supply procedures all along. This helped greatly for the development of checklists and served as training for the whole team.

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HEIDI Maiden Flight, March 2019

HEIDI had its successful maiden launch to 1’141m above ground in Val de Ruz, Switzerland, with ARGOS in March 2019.

Rocket Windtunnel Testing at Sauber Aerodynamics, May 2019

To characterize the aerodynamic parameters of the rockets, both Team HEIDI and Team EIGER (EPFL Rocket Team) tested their rockets at Sauber Aerodynamics facilities in Hinwil, Switzerland.

A team to make it happen

For 10 months, 30 students worked voluntarily on project HEIDI besides their studies. They were mechanical engineers, electrical engineers, physicists, computer scientists, material scientists and management & technology students – a mix of Bachelor, Master and PhD students.

Driven by the passion, they made the impossible possible for ARIS and carried a statement about interdisciplinary teamwork and the strength of Swiss Universities into the World!

>> get to know the rest of the ARIS team

Moments after the award ceremony – what a year!

Partners to make HEIDI fly

Without the tremendous amount of support from our academic and industrial partners, our success story would not have been possible. Thank you very much for supporting project HEIDI and ARIS!

– The enablers of project HEIDI –

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