Proyectos | Leem

El proyecto Hefesto comenzó en 2022 con la idea de construir un cohete sin piezas impresas en 3D ni uniones atornilladas, a diferencia de lo que hacíamos en los proyectos LEEMUR y FORTVNA. El objetivo era hacerlo lo más económico posible, con electrónica mínima, y construido íntegramente en fibra de vidrio.

Durante el lanzamiento del 23 de diciembre de 2022 se lanzó el Hefesto v1. Era un cohete muy pequeño que sentó las bases para el desarrollo posterior del Hefesto v2. Estaba propulsado por un motor Julian, y debido a un fallo en el diseño de estabilidad al salir del riel de lanzamiento, el cohete se volvió inestable y cayó al suelo a pocos metros del riel. No obstante, la fabricación del soporte del motor usando fibra de vidrio y corcho, así como la construcción de las aletas y el soporte de aletas en fibra de vidrio, estableció la base para el Hefesto v2.

El Hefesto v2 se lanzó el 13 de mayo de 2023. Era un cohete muy similar a LEEMUR, pero con muchas menos piezas impresas en 3D, reduciendo significativamente su peso, y sin uniones atornilladas. La punta del cohete, junto con algunos otros componentes, continuó siendo fabricada en PLA impreso en 3D, ya que no se encontró una alternativa viable para producirlos en fibra de vidrio u otros materiales dentro del tiempo y recursos disponibles. Este lanzamiento fue un éxito rotundo: el Hefesto v2, propulsado por un motor Julian, alcanzó una altitud de 950 metros, marcando nuestro apogeo más alto hasta la fecha. La separación y recuperación del cohete también fueron impecables, representando uno de los mayores éxitos en la historia reciente de LEEM

Inspired by the Roman mythology goddess Fortuna, the Fortvna rocket is a prototype of a CanSat Launcher that began development at LEEM in 2022, with Gabriel Arenas as the project leader. The design initially included space to launch 12 CanSats to an apogee of 1 km, although it was later updated to accommodate 9 CanSats. The rocket had a height of 202 cm in version 1, and 177 cm in version 2, both with a diameter of 181 mm, and it used an SRAD Conde Julian motor for propulsion.

The first launch of this rocket took place on December 23, 2022, resulting in a partial success, as the Conde Julian motor experienced some performance issues, preventing the rocket from achieving stable flight. The weights simulating the CanSats were successfully deployed, but the mechanical separation system did not operate optimally.

The second launch was carried out on May 13, 2023, resulting in an explosion on the launch rail due to an unexpected failure in the Conde Julian motor. This version of the Fortvna, named Fortvna 2.0, featured improvements to the separation system and aerodynamics to achieve better stability upon exiting the launch rail, although these improvements could not be tested.

The Fortvna project continued as a learning project for the new team members during the following academic year (2023–2024). Two teams, Frigg and Freya, were formed, each tasked with building their own rocket and competing to see which would achieve better results. Ultimately, these rockets were intended to be launched in a campaign that never took place, as the program was canceled before it could conclude. The program was canceled due to organizational issues, a lack of team resources, and the infeasibility of conducting a launch that year.
Nevertheless, despite its cancellation, the Frigg and Freya teams' program is considered a success, as it served as fundamental training for the new members of the association.

El proyecto URSA es el cohete que presentó LEEM para la competición EuRoC24. Es el cohete más grande jamás construido por el equipo LEEM y representa el mayor desafío tecnológico que el equipo ha enfrentado hasta la fecha. Con este cohete, el objetivo era competir en la categoría de motores sólidos de 3 km, y en este caso el motor era SRAD (Student Researched And Developed).

URSA tenía unas dimensiones de 3 m de altura y 158 mm de diámetro. El motor diseñado para esta misión fue el SM12, que utiliza Rocket Candy como propelente y es hasta la fecha el motor sólido SRAD más potente de España. El cohete llevaba dos paracaídas: un paracaídas de frenado (drogue chute) y un paracaídas principal, junto con un sistema de separación basado en la liberación de aire comprimido.

Las cargas útiles transportadas por URSA fueron creadas por CREA, una asociación de robótica y electrónica de ETSIDI (UPM). Una de ellas consistía en un experimento de fluidos en microgravedad, que no pudo volar debido a problemas de fugas, y la otra era un sistema de transmisión de vídeo en tiempo real.

Tras varias revisiones por parte de los responsables de EuRoC, finalmente se autorizó el lanzamiento de URSA el último día de la competición, el 14 de octubre. La ignición del motor SM12 fue nominal, al igual que el ascenso inicial de URSA. Sin embargo, después de solo unos segundos de vuelo y a una altitud desconocida (ya que no se obtuvo telemetría), el cohete se desintegró en vuelo.

Tras analizar los pocos restos de URSA que pudimos recuperar, se determinó que el problema fue una activación prematura del sistema de separación de CO₂ por parte de la electrónica. Este sistema debería haberse activado cuando el cohete estaba cerca del apogeo, momento en el que su velocidad habría sido mucho menor y, por lo tanto, la presión dinámica que actuaba sobre él mucho menor. Al activarse prematuramente, la presión dinámica externa impidió que el sistema de separación funcionara correctamente. Como resultado, la presión generada internamente por el cartucho de CO₂ activado no tuvo forma de liberarse, provocando finalmente la explosión del cohete.

URSA es, hasta ahora, la misión más grande llevada a cabo por LEEM en su historia, y ha sentado las bases para muchas misiones futuras y posteriores participaciones en EuRoC y otras competiciones.

URSA es, hasta ahora, la misión más grande llevada a cabo por LEEM en su historia, y ha sentado las bases para muchas misiones futuras y posteriores participaciones en EuRoC y otras competiciones.

The LEEMUR rocket series began development in 2021, being the first rockets developed at LEEM during the team’s new stage, which started in 2020. The main goal of the LEEMUR rocket series is to serve as technology demonstrators, allowing the team to test manufacturing processes and new systems developed in the workshop. The person who led most of the design work for the entire LEEMUR series was the head of the design department, Víctor Santurino Salmerón.

The design of the LEEMUR series evolved with the development of the different rockets that composed it, but most LEEMUR rockets shared the following characteristics:

Apogee

LEEMUR series rockets have a theoretical apogee of 1000 m

Payload

Able to carry 1kg of payload allowing it to be perfect for testing subsystems

Deploy system

This rocket has a mechanical separation system that allows it to be reusable

Propulsion

LEEMUR rockets are powered by LEEM-Made JULIAN motor

Size

Height: 1.6 m, Diameter: 7.5 cm

Other Characteristics

LEEM-Made parachute
LEEM-Made electronics LIAS I or LIAS II
Phenolic cardboard fuselage in the first versions, later fiberglass. The progress in fiberglass fuselage manufacturing was largely thanks to the work of design department members Juan Martínez Vázquez and Rafael Gamero Redondo.
Motor mount, electronics bay, nose cone, and other structural parts manufactured with 3D-printed PLA

These features made the LEEMUR an extremely versatile rocket for testing a wide variety of subsystems, as well as an extremely cheap and quick one to manufacture. 3D printing played an important role throughout the entire development of the LEEMUR series, and the low cost of Julian motors allowed for many launches of these rockets: 12 launches in total, with 11 rockets built, since 2 of them were relaunched, although one was never launched (LEEMUR 3).

The first launch of a LEEMUR rocket took place on February 18, 2022. LEEMUR 1 was different from the rockets that followed: it had a phenolic cardboard fuselage, electronics without telemetry that stored data on an SD card, and was powered by a commercial category I motor. The separation system worked with the pyrotechnic charge installed in the commercial motor. The ascent of the flight was nominal; however, the separation did not occur, so the rocket crashed, although the data from the SD card was recovered from the wreckage. This flight was very important for the development of the association, as it allowed us to obtain data and move forward with new manufacturing methods and the implementation of new systems.

Video of the LEEMUR 1 launch: https://www.youtube.com/watch?v=7dlZnL3O6ME&pp=0gcJCYQJAYcqIYzv

On July 19, 2022, six rockets from the LEEMUR series were brought to launch. These rockets were LEEMUR 2, 3, 4, 5, 6, and 7. Some of these rockets were powered by commercial motors, and others by Julian motors. LEEMUR 3 was ultimately not launched that day, leaving the following launch outcomes:

LEEMUR 2: Partial success. Instabilities during guide rail exit due to ignition issues caused the trajectory to deviate significantly.
LEEMUR 4: Failure. The rocket became highly unstable due to propulsion problems and ascended only a few meters before flipping over and crashing into the ground.
LEEMUR 5: Success. Nominal trajectory and recovery.
LEEMUR 6: Success. Nominal trajectory and recovery.
LEEMUR 7: Success. Nominal trajectory and recovery. Successfully tested telemetry electronics developed by Carlos Serradilla Gil. An attempt was made to relaunch it given its good condition, but the attempt was eventually aborted.

For more information about the launches that day, watch the recap video of the live stream: https://www.youtube.com/watch?v=CmGN73k-r3A&t=1347s

The next launch took place on December 23, 2022. Four LEEMUR rockets were taken to the launch: LEEMUR 1.1E TF, LEEMUR 1.2ESA TF, LEEMUR 1.3AS TF, and LEEMUR 1.4S TF. Due to the unstable performance of the Julian motors that day, caused by last-minute modifications, only the first launch, that of LEEMUR 1.1E TF, was successful. The remaining rockets experienced unstable trajectories that caused the missions to fail.

Launch video 23/12/2022: https://www.youtube.com/watch?v=38NiaMIX_D0&t=1760s

The last LEEMUR rocket launch to date took place on May 13, 2023. Two LEEMUR rockets were brought to the launch, named simply LEEMUR “Telemetry” (its purpose being to test the LIAS II telemetry board) and LEEMUR “Drogue-Chute” (its purpose being to test a drogue parachute deployment system). These rockets were refurbished after being recovered from the previous launch. Both rockets achieved partial success: in the case of LEEMUR “Telemetry” due to a non-nominal trajectory despite good results with the electronics, and in the case of LEEMUR “Drogue-Chute” due to a non-nominal trajectory and the simultaneous deployment of both parachutes.

Launch video 13/05/2023: https://www.youtube.com/watch?v=pftNdJBzKy0&t=596s

The major advantages of the LEEMUR series (low cost, easy manufacturing, modularity, and high reliability) made it possible to test countless subsystems, ensuring that all technologies developed at LEEM were flight-tested. These rockets, together with the LEEM-Made philosophy, would define the identity of the team in this new stage of its history.

El SM12 “Aethon” es el motor cohete sólido desarrollado por estudiantes más grande de España. Su diseño fue liderado por Álvaro Albaladejo, entonces Líder del Equipo de Propulsión. Cuenta con cuatro granos de 1 kg de propelente Rocket Candy. El motor tiene un diámetro de 104 mm, una longitud de 853 mm y está fabricado íntegramente en acero. El motor SM12 fue diseñado específicamente para impulsar un cohete del tamaño y peso de URSA hasta una altitud de 3 km, de acuerdo con los requisitos de la competición EuRoC.

Su desarrollo implicó enfrentar nuevos desafíos, como la cocción y moldeado de granos de propelente mucho más grandes, lo que dificultó significativamente el desmoldeo y el posterior ensamblaje en el motor. También fue necesario añadir protecciones térmicas a ciertas partes del motor, ya que el tiempo de combustión era mucho más largo que en motores anteriores. Estas protecciones térmicas incluían ablativos de corcho fabricados por el equipo de propulsión, así como el uso de siliconas RTV, inhibidores de fibra de vidrio y separadores.

Se realizaron un total de dos pruebas estáticas completas del motor, y se utilizó una vez en vuelo, impulsando el cohete URSA en la competición EuRoC24 el 14 de octubre de 2024. Las pruebas de este motor se llevaron a cabo mientras se monitorizaban tantas variables como fuera posible: el empuje se midió con una célula de carga, la presión de cámara con nuestro sistema de medición de presión de cámara desarrollado internamente, y las temperaturas en varios puntos del motor con termopares, continuamente durante toda la prueba.

Gracias a todos los datos recopilados, el SM12 Aethon se ha convertido en el motor más fiable desarrollado por LEEM, y ahora sirve como base para futuros motores basados en Rocket Candy, mejorando y optimizando varios aspectos de este diseño.

Vídeo de la prueba estática del motor SM12 Aethon: https://www.youtube.com/watch?v=iQndP1tIEH8

Vídeo de la prueba estática del motor SM12 Aethon: https://www.youtube.com/watch?v=iQndP1tIEH8

The Julian motor series was the first series of solid motors developed by LEEM, with development beginning in 2021. The design was led by Nicolás de Jong and Germán Pérez, and the manufacturing of the propellant and nozzles was carried out entirely by members of the propulsion department.

The Julian motor is capable of reaching 600 Ns of total impulse, measuring 373 mm in length and 38 mm in diameter, with a maximum nominal chamber pressure of 40 bar. The motor incorporated four grains of solid Rocket Candy propellant. Its casing was made of aluminum and its nozzle of stainless steel, not the optimal materials for this type of rocket motor, but the best in terms of material cost and ease of manufacturing.

It is the most frequently ignited motor by the association to date, with over 20 ignitions between tests and launches. The Julian motor was responsible for powering the vast majority of the LEEMUR series, as well as the Hefesto v1 and Hefesto v2 rockets.

After many tests, firings, and design iterations, the latest versions of the Julian motor became one of the cheapest and most reliable motors that can be used to propel a sounding rocket to altitudes below 1000 meters.

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The Conde Julian motor is the evolution of the Julian motor. It is larger, wider, and uses five grains of Rocket Candy instead of four, with each grain being bigger than in the previous version. The design of this motor was led by Nicolás de Jong, Germán Pérez, and Sara Santos, and, as with its predecessor, almost all of its parts were manufactured by members of the propulsion department.

Due to its configuration, the motor reached chamber pressures of over 100 bar, which added an additional structural challenge not present in the Julian motor. This configuration was necessary given the manufacturing limitations of the tools available at the time. For example, the stainless-steel nozzle had to be manufactured on a manual lathe in the team’s workshop, which, due to its small size, limited the maximum diameter that could be produced. This resulted in a motor with dimensions of 60 mm in diameter and 589 mm in length.

The Conde Julian motor was responsible for powering the Fortvna rockets, the “CanSat Launcher” project that began development at LEEM in 2022. In both launches, the motor behaved in undesired ways, despite having achieved successful static tests beforehand. In the first Fortvna launch, the motor failed to achieve nominal ignition, which meant it did not provide the necessary thrust for the rocket to reach stability upon exiting the launch rail. In the second Fortvna launch, the motor exploded after ignition, even though it had successfully passed a static test earlier that same day.

The challenges arising from the development of this motor brought the project to a critical point. Additional tests were carried out later with a new test stand and a chamber pressure measurement system, which provided information showing that the motor sometimes failed to withstand pressures above 90 bar with the structural configuration used at the time. Fernando Silva Cuenca, a member of the propulsion department, developed a new structural design for the Conde Julian motor, greatly increasing its reliability. Despite these improvements, the Conde Julian suffered another failed test due to irregular combustion that caused overpressure.

Because of all the ignition irregularities presented by this motor, and since the Fortvna project was indefinitely frozen, the development of the Conde Julian motor was also halted, as resources were redirected to the development of the new motor that would power our EuRoC24 rocket: the SM12 – “Aethon.”

En este proyecto se llevará a cabo el desarrollo del primer motor líquido de la asociación, un hito pionero que, en caso de completarse con éxito, se convertirá también en el primer motor líquido estudiantil de España.

El diseño elegido corresponde a un sistema pressure-fed que empleará óxido nitroso como oxidante y etanol como combustible, con una presión de cámara de aproximadamente 30 bar.

El objetivo final es embarcar este motor en un cohete y realizar un lanzamiento. Para alcanzar esta meta, se seguirá una estrategia progresiva: en primer lugar, se desarrollará un motor a escala reducida, que actuará como demostrador tecnológico y servirá para adquirir experiencia práctica en el diseño, la integración y las pruebas de propulsión líquida. Esta primera versión será destinada a ensayos en banco, mientras que la versión final será ensayada y, posteriormente, volará a bordo de un cohete experimental.

Con este proyecto, la asociación no solo busca un avance técnico significativo, sino también sentar las bases para futuros desarrollos dentro de la cohetería experimental. Además, lograr este objetivo supondría alcanzar un hito histórico: el primer motor líquido estudiantil desarrollado en España.

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