The Hound – Sustainer near Apogee (Background Source/wikipedia, Mission Patch by Maximilian Trenkmann)

Short Description

Simulation details (OpenRocket)

The Hound, a two-stage rocket with commercially available motors to achieve the highest possible altitude:

  • Booster: Cesaroni Pro 98 N5800
  • Sustainer: Cesaroni Pro 75 M2245
  • Peak Altitude: > 100km (Sustainer)
  • Peak Velocity: > Mach 5 (Sustainer)


The Project

Our objective is to build a two-stage rocket based on commercially available motors, which is optimized to achieve the highest possible altitude. Nevertheless, up until now anything above 32.3 km (current record holder HyEnD/Stuttgart) would set a new “European university amateur club record” – and that is what we want to go for! In Spring 2019, a US based student team successfully passed the Kármán line and established a new world record for university teams.

The selected motors have a combined total impulse of about 30,000 Ns. For comparison purposes, this would be enough to accelerate a motorcycle to about 400kph (250 mph). Because our rocket is much lighter, it will accelerate to about 5500 kph (3400 mph). At this speed, a marathon race would be finished in less than 30 s. Our simulations indicate that, dependent on actual aerodynamic parameters, an altitude of more than 100 km (62 mi) above ground could be achieved.

These numbers present quite a challenge in various aspects. On one hand, we need to build different parts as light and small as possible to be able to obtain that speed and altitude. On the other hand, those values raise the requirements e.g. for toughness and heat resistance, demanding special materials and manufacturing techniques. All in all this is a tricky multi-variable optimization problem.

Other challenges include:

  • Ignition of upper stage motor
  • Determination of apogee altitude
  • Apogee detection and barometric altitude detection for two-stage parachute deployment
  • On-board video recording
  • Radio transmission of sensor data and – most importantly – landing coordinates.

All that said, the biggest challenge for Europeans is to find a launch site with an appropriate altitude waiver and safety radius. Two viable options are known to us:


Key Components

  • Flight Computer: inertial measurement; GPS data; liftoff detection, separation, upper stage motor ignition and recovery initiation; telemetry
  • Central Ground Station: direct connection between operator and rocket, visualizes relevant parameters in real time
  • Autonomous Ground Stations: multiple distributed RF repeaters extend reception area of central ground station; autonomous logging of received data
  • Airframe: nose cone manufactured out of high-temperature resistant glass fiber reinforced plastics; rocket motors are structural parts of the airframe
  • Staging Adapter: integrated into sustainer tail cone: lightweight, stiff and compact
  • Recovery: two-stage design based on aramid drogue parachute and nylon main parachute
  • Fincan: lightweight but full-metal design manufactured by Direct Metal Laser Sintering (DMLS), for heat dissipation and high strength; interior isogrid-spar structure enables a superior strength-to-weight ratio

Presentation of the project “42km – The Hound”

Further details about the project are included in the following videos:

See the presentation of the project by the project lead Christoph Fröhlich at the Space Events 2019 (German only):

Chronology and Milestones

Early Launches

  • In August 2016 the Space Team attended a rocket launch event in Manching, Germany, where the Space Team’s first ever two-stage flight took place. A motor with low thrust was intentionally chosen in order to be able to easily observe the sequence of the two-stage flight from the ground. This flight served as a successful proof of concept for the two-stage flight.
  • Not long afterwards the team’s very first supersonic flight took place. With a maximum acceleration beyond 30g, the rocket was accelerated to a velocity of 390m/s (Mach 1.14) within 1.4s. Despite aerodynamic disturbances, that affected the barometric sensor while passing the transonic speed region, the flight computer’s apogee detection worked without a hitch.
  • After many hours of construction, “The Hound” began to take its final shape. In May 2017, the upper stage of The Hound celebrated its maiden flight in Roitzschjora, Germany. The goal of this launch event was to test the new recovery system, the automatic apogee detection, the attitude estimation, and the radio modules with configurations almost identical to the planned final configuration, that will be used for the European record attempt.
  • In early 2018 final tests were conducted in Roitzschjora, Germany, and “The Hound” was launched in a two-stage configuration before the rocket was shipped to the US.

First Full-Configuration Launches

  • The first attempt to reach space was performed in 2018 in Nevada, USA. Due to an error with the ignition system, the upper stage motor was not ignited and only an altitude of approx. 13km was reached. Read more about the results in this blog entry.

Because the launch in the fall of 2018 was not successful, the TU Wien Space Team decided to extend the project for another attempt in 2019 – “The Hound 2” – with an adapted concept based on previous experiences:

  • Improved telemetry integration including new antenna design
  • Iridium satellite communication system for redundancy
  • New upper stage ignition concept
  • New on-board video cameras

In September 2019 another record attempt was performed. Despite several delays The Hound 2 was launched, but the flight ended too early: The upper stage broke apart shortly after engine burnout. Unfortunately, the avionics unit disintegrated, the data recording failed and neither of all four on-board cameras could be found afterwards. Additionally, the radio communication to the booster was interrupted midflight, which is why the booster couldn’t be recovered. A more detailed final report can be found at final report 2019.

During 2020 work on an update was done: “The Hound 3”.  The most important changes were:

  • Integration of an avionics unit inside the coupler between the two stages which contains a camera, an autonomous GPS tracker and a GPS independent tracker (“bird finder”).
  • A new backup device inside the booster
  • The top will be built from titan, instead of aluminum.
  • The electric connection of the headend ignition will be built more robustly as just before the start of “The Hound” a cable broke and had to be fixed in a short amount of time right at the launch pad.
  • A change in the starting procedure in order to be more independent from the quality of the radio communication near ground.
  • More tests and test flights are supposed to make the platform “The Hound” more reliable, get rid of possible difficulties and give the team the possibility to further bring the starting procedure to perfection.

In autumn 2020 another attempt was planned. Unfortunately, the event Balls — like many other events — got canceled due to the global COVID-19 pandemic. However, we were still able to implement all updates and improvements, which were planned for The Hound 3. Thanks to Portugal Space we even got a great opportunity to test all that on European soil: EuRoC 2020. With the sustainer reaching a max. altitude of about 9km the launch in Portugal marked our team’s highest rocket flight in Europe to that time and was a great success overall. The new and updated avionics worked flawlessly and, for the first time, we were able to watch five on-board videos after the launch (2x booster, 2x sustainer, 1x interstage). Despite all those achievements there is still work to be done since the main parachute of both stages did not deploy.

Again, in 2021 we did not have the chance for another record attempt due to active travel restrictions. But we used the time for test flights in Europe, because despite the successful flight in Portugal 2020 there was still room for improvements. Two successful two-stage test flights were performed in Poland in June and November 2021, increasing the team-internal altitude record on European soil to 11,800m.

True to the motto “the third time’s the charm”, the team was optimistic that the third attempt performed in 2022 will be a great success. Two rockets were launched successfully, “The Hound Minor” and “The Hound Major”. But both upper stages experienced an aerodynamic instability close to their maximum velocity after upper stage ignition, and reached a maximum altitude of 21.4 km only. But these launch campaign was still a great success for the team, read more about the results in this report.

Plans for 2023

We are currently evaluating options for another attempt in 2023, stay tuned!


Simulation Results

The software packages OpenRocket and RASAero were used to perform flight simulations. The results for “The Hound 2”, launched from the Black Rock desert, are presented below:

Project team

Past and present team members (in alphabetical order)

  • Christian Plasounig (Projektleiter bis 2018)
  • Christoph Fröhlich (Projektleiter ab 2019)
  • Andreas Bauernfeind
  • Tobias Bauernfeind
  • David Birschitzky
  • Florian Guggi
  • Alexander Hartl
  • Michael Hauser
  • Thomas Hirschbüchler
  • Patrick Kappl
  • Peter Kremsner
  • Benjamin Luxbacher
  • Ulrich Meisl
  • Simon Neumüller
  • Moritz Novak
  • Julian Präsent
  • Reinhard Rath
  • Stefan Schaffer
  • Stefan Schindler
  • Manuel Schleiffelder
  • Benedikt Stingl
  • Silvia Tirler