History: Stratos I

Introduction

Several years after DARE was founded the members of the team felt they had come to point were serious achievements could be made. They set their aim to shatter the altitude rockets for amateur rocketry in Europe at that time. Using their experience in KNO3-Sorbitol engines they designed a new system with a special clustered booster motor, and sustainer motor capable of reaching 15 km. Custom electronics and systems for stage separation  and recovery were designed and tested. Their efforts culminated in the launch of Stratos I in 2009 from Esrange in Sweden. The rocket reached 12.5 kilometer altitude due to a delayed second stage igniter and broke the European record for amateur rocketry in Europe. A record DARE still holds today.

Technical Specifications

The Stratos rocket consisted of two stages. The first stage was a cluster of four booster motors, each with a thrust of 1.5 kN, or 150 kg, which propelled the rocket close to the speed of sound within the first few seconds of flight. At burnout the boosters were jettisoned and the sustained motor further propelled the rocket in ten seconds to approximately three times the speed of sound (Mach 3, aproximately 3000 km/h).  Inertia then carried the rocket to its apogee at 12.3 km.

From the start it was decided not to recover the booster section of the rocket. Only the top section of the rocket with valuable data, electronics and experimental payload was to be separated from the main stage and land by parachute. The flight computers had a down-link for telemetry, ensuring complete evaluation of the flight, even if the payload was not recovered. The payload contained a Inertial Measurement Unit (IMU) from the TU Delft. This IMU had been developed by Aerospace Engineering students at the TU Delft as part of their final Bachelor design project and was built and flown as part of Stratos I.

The launch campaign occurred at Esrange, a professional rocket base in Kiruna, Sweden, 200 km above the polar circle. During the launch campaign the team kept a day-to-day weblog, which can be found here. There are also many pictures of the launch campaign on this weblog.

Challenges

B-payload-install

Insertion of payload and recovery system into sustainer stage at Esrange Space Center.

Unfortunately the intended separation of the flight computer and payload module from the main stage did not occur: due to the relatively low air pressure the pyrotechnic charge which would cause the separation was unable to fire. As a consequence the parachute never deployed and the rocket impacted the ground after a 12 km free fall.

A rescue mission was setup the following summer to recover the remains of the rocket which were discovered after a day long hike to the last known GPS location. The remains are currently on display at the korolev Lab as study material for aspiring DARE students.

Sponsors

The main sponsor for Stratos I was Dutch Space. Executive sponsors were the TU Delft and Swedish Space Corporation. Participating sponsors were Rebel Space, VSV Leonardo DaVinci, Inducar, Caveman Rocketry and NXP Semiconductors.