Airbus Sloshing Rocket Workshop 2021
Competition Regulation

1. Introduction

1.1. Background

Modelling the behaviour of sloshing liquids is of significant interest in various fields of the aerospace industry.

In aircraft design, the study of fuel movement in tanks is of paramount importance for the design of the fuel management control system, the evaluation of the handling characteristics of the aircraft and ultimately the assessment of the structural integrity of the containment structure [1].

For modern satellites, the design is often driven towards lightweight structures, high pointing accuracy and long life expectations. These can result in a large proportion of the overall weight being allocated to the liquid propellant. Therefore the movement of the liquid fuel within its containers can significantly affect the dynamics of these systems, during in-orbit controlled manoeuvers and atmospheric gust encounters in the launch phase [1].

1.2    Competition Background

The Airbus Sloshing Rocket Workshop 2021 is an online competition in which teams are tasked to design a low cost reusable rocket which is destabilised by the movement of water stored within an unpressurised tank. The rocket design shall incorporate mechanisms to manage the dynamic forces introduced by the sloshing water to maximise its range, time of flight and liquid payload capacity. The controlling mechanism can be designed based on passive and/or active means and its performance is a key aspect of the design.

This challenge aims to simulate the conditions experienced by real world aerospace vehicles containing liquid propellant.

The participants would be provided with a series of lectures focused on the sloshing and rocket designing challenge.

The objective of the competition is to design the rocket and stabilisation system. The description and justifications for the design are to be presented in the format of a design report and supported by calculations, simulations and/or results from prototype testing.

Reports must be submitted before May 15th at 00:00 UTC.

The 5 best teams from this round would promote to the final round. In this stage, the teams would meet the AIRBUS team to discuss their design proposals and defend their reports in a 20 minutes presentation format plus 10 minutes for questions.

2. Technical Requirements

The rocket design must conform to the requirements outlined in this document.

2.1    Physical

The rocket’s total dimensions shall not exceed the following:

  • Maximum length = 1.5 m;
  • Maximum wingspan = 2.25 m;

The launch angle will be 85 degrees, an offset of 5 degrees from vertical, with a tolerance of +/- 3 degrees.

The primary structure of the vehicle shall be formed of readily available items, such as plastic bottles, forming two or more water tanks:

  • 1 unpressurised tank containing a minimum of 500ml of water. The tank must contain 50% water and 50% air to generate sloshing loads. The fill level at 50% volume must be clearly marked to facilitate easy visualisation for the judges.
  • 1 or more pressurised tanks containing water for propulsion. The total mass of the propellant must be no greater than the mass of the sloshing liquid.

The total rocket weight at take-off shall not exceed 5 kg when filled with liquid.
The arrangement of the tanks does not have to conform to a traditional rocket shape. Teams are encouraged to consider a range of aircraft concepts and evaluate their potential benefits and drawbacks.

2.2    Launch Mechanism

The rocket must be launched vertically at a pressure less than 10 atmospheres [or 147 psi].

The rocket design shall incorporate a means of pressurising the propulsion tanks with air. The design should present how the tanks would be filled.

Only air is permitted as an inflation gas and no propellant other than water is permitted. This forbids the use of propellers, propulsive gas, engines and lighter than air gases such as helium.

The ratio of air-to-water inside the propulsion tank or tanks (not the payload tank) is customisable and should be exploited to optimise the performance of the vehicle.

2.3    Control Mechanism

The design shall incorporate a means of controlling the descent of the rocket to counteract the destabilising motion of the sloshing liquid. Details of how the sloshing liquid behaviour has been predicted and justification for the embodied solution shall be provided as part of the design submission. This could be achieved by using passive or active means or a combination of both:

  • Passive Control: e.g., baffles. Any singular baffle inside the tank cannot cover more than 50% of the cross-sectional area of the tank.
  • Active Control: e.g. control surfaces.

2.4    Materials and Cost Items

The rocket design shall not rely on COTS (Commercial off-the-shelf) items costing in excess of €300. A bill of materials and cost breakdown is required as part of the design submission. Cost efficient solutions will be awarded more points.

The total cost of the rocket must not exceed €500.

2.5    Flight Performance

The simulated flight would be marked attending the following ecuation:

                                                                 Flight Score = (Distance [m] +Time [s]) x Payload [kg]/TOW [kg]

3. Competition Marking

The overall competition winner will be decided based on the overall score punctuation between 0 and 400 with the following details. The primary submission will be a report, supported by (if possible) evidence of any physical testing, which will be eligible for extra marks.

Introduction [5%]
 – Background information on the challenge of sloshing liquid propellants in the aerospace industry.
 – Overview of the design approach taken.
 – Team organisation.

Requirements Capture [5%]
– Using a table format, define the requirements for the design.
– Mandatory and optional requirements shall be clearly identified.

Concep Design [15%]
– Descriptions of several design concepts including explanations of how each concept is derived from the design requirements.
– Justification for concept selection, supported by explanations of how the mandatory requirements will be met by the chosen concept.
– Concept selection may include basic sizing and performance calculations.

Detailed Design [45%]
– Explanation of how the sloshing behaviour has been predicted and how the control mechanism has been designed to tackle the dynamic loads introduced.
– Finalised vehicle geometry, possible generated from a 3D CAD model.
– An accompanying analysis which may include design trade studies and optimisations to maximise mission performance.
– Simulations that support your design.
– Detailed description of manufacture including: Bill of Materials, component manufacture, assembly sequence and a cost breakdown.
– Explanations of how safety and operability have been considered in the design of the vehicle. 

Design V&V [15%]
– An assessment of the final design against the requirements showing how all the mandatory requirements have been met.
– A test plan showing the means by which compliance with each requirement has been demonstrated by simulation or prototype testing.

Conclusion [5%]
– Conclusion summarising design outcomes, reflecting on initial objectives.

General Report Quality [10%]

4. Participation Fee

The participation fee covers access to the Webinars provided  by Airbus and Ariane Group and is as follow:
Team: 75€ (1)

Important remarks:
(1) Each non-EUROAVIA member in the team is subject to the payment of an extra 40€.
EUROAVIA International will verify the membership status for every member in every team and reserves the right to issue the extra fee in (1) to each non-EUROAVIA or inactive EUROAVIA member.
Shall you have any questions, please enqurie us at

5. Application

The applications will be processed based on the rule first come, first served.
Once you submit your team application you will receive a confirmation e-mail. This does not mean your place in the competition is secured.
After the applications close and have been processed the selected teams to participate will receive an email confirming their acceptance and further information on the payment of the participation fee.

The applications start on Jan 15th at 16:00UTC in

The application period would be opened until Jan 31st at 23:59UTC.

6. Bibliography

[1] F. Gambioli und A. G. Malan, “Fuel Load in Large Civil Airplanes” in International Forum on Aeroelasticity and Structural Dynamics, Como – Italy, 2017.