Students from Delft Aerospace Rocket Engineering, or DARE, will try to break the European height record for student and amateur rockets on 24 July. A larger and much heavier third version of the Stratos rocket is used for this.

With Stratos Iii, 130 TU Delft students from DARE want to break the current height record on Tuesday evening, July 24th. This record is in the hands of German students from Stuttgart, who reached a record high of 32.3km on 8 November 2016 with their 7.5 meter long Heros 3 rocket.

A spokesman for the student team does not want to make a prediction about the expected height that has to be achieved on Tuesday, but says that the goal is to exceed at least 32.3km. In the past it has sometimes been stated that the Kármán line must be reached at a height of 100 km, but according to the spokesman ‘that will not work with this generation of missiles’.

Stratos III is with a length of 8.2 meters and a weight of 330 kg longer and significantly heavier than its predecessor, Stratos II +, which reached a height of over 21 km in 2015. This previous fresh had a length of 6.9m and weighed 185kg. “The weight gain comes from the fact that Stratos III takes a lot more fuel and the empty weight of Stratos III is less than that of Stratos II + due to the use of more advanced, lighter materials,” said the spokesman.

The new missile uses the same type of DHX-400 rocket engine as the Aurora engine from the previous missile, although the height and diameter of the current Nimbus rocket motor are slightly larger. This is a hybrid rocket engine, in which elements of a solid fuel engine and of a rocket engine with liquid fuel are combined. As with the Aurora, N2O is used as an oxidizer and sorbitol, paraffin and aluminum form the fuel, or as the spokesman calls it: ‘coffee sweets, candle grease, aluminum powder and laughing gas’.

The main difference between the rocket engine of the previous rocket and that of the current Stratos III is the fact that the nitrous oxide is pumped into the combustion engine more quickly in larger quantities. With the Stratos II + this was 2.6 kg / s, while in the Nimbus engine 6kg / s happens. This achieves a higher thrust, which in combination with the larger amount of fuel should lead to a new European record.

Actually the record attempt should have taken place on Friday, but the moment has been postponed to Tuesday 24 July because an essential part is still missing. It concerns the so-called flight-termination receiver , which is crucial for safety. This part, which protects the launch platform during the launch, has been sent back to the American manufacturer for modifications. In principle, this part must be back in time for a launch on July 24, but it is not at all certain. Possibly the days after Tuesday can also be used for the launch.

Stratos IIIStratos III
On the left you can see the rocket engine and also the flight computer.

As far as electronics are concerned, the majority of the nose cone of Stratos III is occupied by the flight computer consisting of several specially made PCBs. This computer collects all data from the sensors and actuators, which are processed by NXP microcontrollers. In addition to flight data, the PCBs also send a live video feed back to Earth via antennas. The nose cone also contains a box with avionics from the Dutch Aerospace Center. With the help of gyoscopes and data from GPS and Galileo satellites, the location and position of the rocket are stored. This is then forwarded to a ground station via the flight computer.

The record attempt takes place at the El Arenosillo launch site in the south of Spain. This is owned by the Spanish Space Agency, the Instituto Nacional de Técnica Aeruspacial. We chose this location because the Spanish organization helps with the record attempt. Moreover, the weather conditions and the hustle and bustle of air traffic at this location are more favorable than, for example, in the Netherlands.