Stratos IV

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At the end of August 2018, work on Stratos IV began. The team was determined and committed to achieving their mission:

“Design, build, test, and launch a rocket which will break boundaries in Fall 2021.”.

Many new design choices and modifications were implemented onto the Stratos III design, which showed potential but had room for improvement. 

Unfortunately, when at the launch site, the team decided to not go through with the launch. Troubleshooting with the Quick Disconnect (QD) throughout the day did not lead to a solution that the team was confident in or predictable, but most of all safe. After discussions between management and the crew at the pad, it was deemed infeasible and unsafe to continue any further. As this was their final launch window, the team had no other option than to return to Delft.

The goal of launching the Stratos IV rocket was, besides showcasing the huge leaps in the capability of students and breaking the European record, to allow students to gain hands-on experience with designing, building, testing and finally launching a real, space-capable rocket. Of course, it was disappointing for the team that not all mission goals were met, but it’s still a great achievement to have finished the rocket, fundraised enough to launch, and made it to this point, all through the Covid-19 pandemic. The most important part of launching is doing so safely, especially when things don’t go according to plan. Therefore, we knew this was the right decision as safety is always DARE’s top priority, but a challenging one to take given how much work has gone into this.

We want to extend our thanks to all of you. Family, friends, sponsors, professors, fellow rocket enthusiasts and students alike, you have all had a part in our journey and for that we are eternally grateful. We would also like to thank @intaespanaet for their support through the years.

The Team

Stratos IV is designed and built by a team of 16 full-time and 60 part-time engineering students from Delft University of Technology.

Our Partners

Stratos IV could never have been built without the support of all her partners from industry and academia. 

The Launch Site

Stratos IV is launching from El Arenosillo Test Center (CEDEA) located near Mazagón, Spain

Stratos IV is a 8.3m tall sounding rocket designed break records. Over 120 students over the span of 3 years have dedicated their time and effort to make it a reality.

All of the components were designed, produced, and tested by us. However, some parts require help from our partners, such as the 3D-printed titanium nozzle.

Flight Computer:

The brain of the rocket. 7 custom-designed PCBs control parachute deployment, flight data storage, control of the telemetry systems, and more. It  includes IMUs to measure the accelerations in flight, redundant black boxes, and static pressure sensors.

Recovery Module:

Ensuring a safe landing. A dual parachute system, with a drogue and a main parachute, slows down the nosecone before touch-down. A new hot gas deployment device allows for drogue parachute deployment in supersonic flight conditions. The recovery plate, takes all the parachute forces, and can hold more than 1600 kg! A heat shield protects the delicate parachute wires.

Drogue Parachute:

Designed by our recovery team, ejected after nosecone separation, and pulls out the main parachute.

Roll Control:

Making sure that the rocket is stable during flight. 4 nitrous oxide monopropellant thrusters, producing 40N each, keep the roll rate of the rocket within reasonable bounds.

Oxidiser Tank:

Holds 174kg of nitrous oxide, stored at 60 bar. It uses an 1.5mm thick aluminium liner overwrapped with carbon fibre to increase strength and stiffness. The oxidiser tank makes up most of the rocket, standing over 4.7m tall.

Engine Bay:

Controlling the engine. It allows for the flow of 6kg/s of nitrous oxide from the oxidiser tank to the combustion chamber through the feed system in its centre. The engine control unit controls all the valves and motors in the engine bay. The flight termination system allows for a safe launch, automatically terminating the flight if the vehicle flies out of a predetermined safe-to-fly zone.

Composite Combustion Chamber:

Using multiple layers of composite materials to hold the pressure and heat from the hot gases inside the combustion chamber. Large fins ensure stability of the rocket during ascent.

3D printed Titanium Nozzle:

This design saves 10kg from the full graphite design that was used in Stratos III. Small pieces of graphite is used in the hottest parts of the gas flow, which can reach 3000K, while a titanium shell coated with zirconium-oxide is used at the cooler parts of the combustion gases.


8.286 m

27.2 ft


27.8 cm

10.9 in

Dry Mass

108 kg

238.1 lb

Propellant Mass

226.1 kg

498.5 lb

Average Thrust

10000 N

2248.1 lbf

Specific Impulse

180 s

The Mission

Stratos IV is launched from El Arenosillo Test Center (CEDEA) located near Mazagón, Spain. After ignition, the vehicle starts its journey to space, powered by the DHX-400 ‘Nimbus’ hybrid rocket motor. 29 seconds in the flight, the vehicle runs out of propellant and the engine is shut down.
However, the vehicle still has an unprecedented velocity and has already passed the most dense layers of the atmosphere, giving it enough kinetic energy to reach beyond the current European record at 32.3 km. After the rocket has reached its apogee, the nosecone with recovery payload separates from the booster and starts a re-entry, followed by a series of two parachute deployments to slow down the nosecone for sea recovery. The booster is not recovered.

History of Stratos

The first Stratos rocket was launched from Kiruna, Sweden in 2009. This two-stage, solid propellant rocket reached an altitude of 12.3km, which at the time set the European altitude record for student rocketry. Stratos II, the successor of Stratos I, was meant to fly even higher than that, but unfortunately did not lift off due to a misfire of the engine. This lead to a redesign of the rocket, namely Stratos II+. Launched in October 2015 from an INTA facility in Huelva, Spain, Stratos II+ flew to an altitude of 21.5km, breaking our own record set by Stratos I.

Recently the record was broken by the Hybrid Engine Development from Stuttgart, Germany, setting it to 32.3km. Consequently, DARE decided to combine the knowledge that was gained during the Stratos I and Stratos II projects to develop Stratos III, which was being designed to go well beyond that boundary and improve the European student altitude record. The rocket was launched on the 26th of July 2018 from INTA in Spain. 20 seconds into the flight it encountered an anomaly and the vehicle disintegrated. The Stratos III team worked incredibly hard over the past two years and while we were disappointed by the failure, the Stratos IV team recognizes the potential of the Stratos III design. The Stratos IV rocket will, therefore, be heavily based on Stratos III.


A special thank you goes to everyone who supported us during the crowdfunding campaign of Stratos IV:

Jeroen Nijhof
Tammy Holohan
Keppel Aerospace
Bruno van Dunne

Chris Woudstra
Daniel Hooft
Sonia van Lynden
Willem van Lynden
Arjan Fraters

Jesse Rodrigo
Pjotr Lengkeek
Stan van der Lans
Jeroen van Straten
Steven Engelen
Froukje de Groot van Embden-de Jong

Cees en Jacquelien Noordhoek
Manfred Josefsson
Fabio and Paula van Roon
Hoye Lam
Martijn de Milliano
Jos van ‘t Hof

Jasper de Reus
Peter van Gemert
Joao Matias
Mike Spekreijse
Emilio Diaz de Mera
Sander Jahilo
Julio Rivera
David and Ingrid Oliver
Alex van Hooijdonk
Jillis Noordhoek
Marta Mena Gomez
Max Hallgarten La Casta
Christ Akkermans
William Hartwell


Project Stratos is carried out under the flag of Delft Aerospace Rocket Engineering, however it falls under the legal responsibility of Stichting Students to Space.

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