The sounding rocket TELL
Spaceport America Cup 2018
ARIS’ first project consisted of the design, manufacturing, and testing of the first-ever rocket built by the association. The sounding rocket TELL was designed to reach an apogee of 10’000ft at the Spaceport America Cup 2018 with a commercial off-the-shelf solid motor and to be recovered with a dual parachute system. Although the motor caused a catastrophic failure after 1.4s into the flight, TELL won the Charles Hoult Award for Modeling and Simulations.
Over 50 students of ETH Zürich and HSLU contributed voluntarily during 8 months to the project TELL and achieved the extraordinary. With their work, they paved the way for ARIS’ long-term vision and created life-long friendships.
To launch a rocket and to win an Award
At its very first participation at the Spaceport America Cup, ARIS won the Charles Hoult Award for Modeling and Simulations for its technical achievement – one of the ten main awards of the competition. Despite a motor failure and the resulting explosion of the rocket a few seconds into the flight, the project TELL was very well received for its technical and operational excellence.
A statement of technical excellence and teamwork
Team TELL carried the Swiss engineering and organizational excellence to an international platform. Thanks to close interaction and mentoring with partners from industry and academia, the student team managed to build its first own rocket with sophisticated subsystems from almost no experience in rocket science within 8 months.meet the team
Switzerland at its best – two teams, two awards
The Spaceport America Cup 2018 was a full success for Switzerland, its high-standard universities and pioneering spirit. Both the EPFL Rocket Team and ARIS won each an award for technical excellence with their inaugural projects:
Team TELL (ARIS): Charles Hoult Award for Modeling and Simulaitons
Team EIGER (EPFL Rocket Team): Jim Furfaro Award for Technical Excellence
To compete at the Spaceport America Cup
Operations in a harsh environment
The competition takes place in temperatures above 35° in a dusty and tiring surrounding. Preparation, procedures and safety are key.
Learning from established rocketeers
At the cup, ARIS interacts with student teams from renowned universities and experienced judges and aggregates knowledge from the best.
Learning from the experts – the Critical Design Review
The rocket TELL
TELL targets an apogee of 10’000 feet above ground level with a commercial off-the-shelf solid motor. For recovery, a drogue parachute is released by ejecting the nose cone at apogee followed by the main parachute out of the same compartment at 1500 feet above ground level.
As payload, the rocket carried a camera filming biological cells under the extreme launch conditions in a 1.5 CubeSat Unit. The rocket has an altitude control system consisting of three air brakes which are deployed after the motor has burnt out to bring the rocket as precisely as possible to 10’000 feet. Its controller is located on a sensor board with two redundant barometers in the lower body avionics. A WiFi connection links the lower body avionics with the ground communication and the GPS module in the glass fibre nose cone.
Lift-off dry weight: 20.5 kg
Length: 2450 mm
Diameter: 150 mm
Motor: Aerotech M2400T, commercial off-the-shelf
Target apogee: 3048 m / 10’000 ft
Static stability margin: 2.3 cal
Redundant avionics trigger the ejection of the nosecone by pressurizing the parachute compartment with inert CO2. As a result, two parachutes are being ejected after each other: First, a drogue after apogee to stabilize and slow down the descent to less than 32 m/s. At 400 m above ground level, the main parachute is released to reduce the descent rate to less than 9 m/s and provide a safe touch down of the rocket.
Altitude control: airbrake system
Using the aerodynamic characteristics determined with a wind tunnel test, a student-developed algorithm controls the airbrakes that increase the drag to accurately reach the target apogee of 10’000 ft. The algorithm is solving a chance-constrained infinite horizon optimal control problem. Using Monte-Carlo simulations accounting for uncertainty and other effects, a look-up table is stored on the on-board memory and enables a simple implementation on a rocket with limited in-flight computation capabilities.
Catastrophe at take-off
T – 69 minutes
After flawless preparations TELL was installed on the launch rail at 11:20h. The waiting time on the launchpad exceeded one hour.
T – 0
At 12:29h the ignition was successfully initiated, and the rocket lifted off. TELL cleared the launchpad nominally, but a tilt and/or rotation of the rocket could be observed after leaving the launch rail.
T 1.4 seconds
In the middle of the 3 seconds boost phase, the lower body of the rocket violently disintegrated, and the connection to the rocket was lost. Multiple debris could be observed. A catastrophe at take-off (CATO) was detected, and the range was closed.
The CATO was a great shock for everyone, but team TELL didn’t just take the hit and stayed on the mission. A detailed analysis on the ground with judges, experts of the competition and the manufacturer was conducted the same and following day and concluded a a malfunction of the rocket’s motor due to overpressurization from backside burning. The measured thrust curve suggested a non-nominal burning which was confirmed by the manufacturer. Most probably, just had the statistically possible bad fuel grain batch.Download the post flight analysis report
All parts recovered and (almost) intact
The parts of the rocket, including unburnt grain, could be recovered and were subjected to a detailed analysis. The outer structure was almost intact. The inner structure, the payload and the avionics, however, were heavily damaged. Surprisingly, no serious damage could be observed on the motor casing. The distorted lightweight fin section remains as a memorable artefact from the CATO.
Overpressurization from backside burning
The recovered grains, the outside-burnt and burst insulation liner and the observed overperformance suggest that the fuel grain burned faster than nominal, which resulted in backside burning along the wall of the casing.
This created an abnormally high pressure in the motor and the threads of the rear closure of the motor casing weakened, leaving visible abrasion marks on the threads. As a result, the motor disintegrated, released all pressure (explosion) and stopped burning.
The intentional fail-safe mechanism by the failing threads at overpressure prevented further burning and a bigger explosion.
Never give up – the post flight evaluation after the CATO
Spaceport America Cup – Livestream of the launch
Before the launch of the TELL rocket, the project manager tells more about the rocket and the organization.
Spaceport America Cup – House of Switzerland
We proudly represented our country with some raclette and chocolate in the desert of New Mexico.
Spaceport America Cup – Failure Analysis
Here’s a first look at the potential reasons for the break up on the ascent of our rocket during the launch.
Spaceport America Cup – Poster Session
Jonathan Firth (Exec. VP of Spaceport and Program Development of Virgin Galactics) was impressed by our airbrake design.
Spaceport America Cup – Assembly
Before our rocket is inspected by the judges, it needs to get assembled first. Check out the timelapse of the assembly!
Spaceport America Cup – the journey to the USA
We arrived safely in El Paso. We met the vice president of the Experimental Sounding Rocket Association!
Spaceport America Cup – Teaser
Time to explain what the Spaceport America Cup is and how our rocket actually works.
Windtunnel testing at Sauber Aerodynamics
Find out in this video how we prepared for finding aerodynamic parameters of our rocket with the help and know-how from Formula 1 experts of Sauber Aerodynamics in Hinwil, Switzerland.
Making of: the nosecone
The nosecone of TELL 1 is made of glass fiber prepreg. The half-shell mould is closed after the layup and subsequently cured in the autoclave at CMAS Lab of ETH Zürich. Do not feed the students while building rockets!
Full scale recovery test: launch in Val de Ruz
It is the first time the team launches a Tripoli Level Two rocket. The self-built recovery worked perfectly, and the team had a blast in the beautiful Jura region of Switzerland.
The Critical Design Review – feedback requested
With the help of our partners from industry and academia, the team figures out what the best final design of the rocket will be like. Thank you very much RUAG Space, Sauber Aerodynamics, Maxon Motor, ETH Zürich and HSLU for your education!
Use of 3D-printers for rapid testing
Christian explains to us how additive manufacturing helps to have a good idea of what the final object will actually look like.
Test-rocket for the airbrake mechanism
Passion starts early: ARIS’s first rocket launched in Kaltrbrunn, Switzerland, with ARGOS. The rocket MESTRAL I tested our first electronics of the airbrake mechanism.