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FEATURE LINEAR MOTION
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W
hen it ended in disappointment earlier this year, the first international launch for Virgin Orbit highlighted the complexity
of space missions – and the importance of every single component specified. While investigations into the reason for the
project’s failure are still ongoing, preliminary evidence suggests that the filter in the rocket’s second-stage propulsion system was dislodged, causing issues downstream and ultimately leading to premature shutdown of the engine. Space missions, however, also need reliable
products such as micromotors. Most orbital launch vehicles, including Virgin
Orbit’s rockets, rely on RP-1 fuel for power. This is a highly refined form of kerosene, which has had additional unwanted compounds removed to produce a cleaner burn and prevent engine damage. RP-1 is mixed with liquid oxygen (LOX) to create a combustion reaction. The nature of this reaction means precise ratios aren’t required –
valves are installed onto the fuel tank pipes. Controlled by servo motors, these valves allow precise control of reactant flow, which means that the fuel mixture can be kept as close to its ideal ratio as possible.
LINEAR SOLUTIONS Unmanned space probes have been used for a more cost-effective and safer method of space study since the first unmanned space mission, Sputnik, in 1957. Small samples of rock and dust are collected from other planets, with return capsules responsible for bringing these samples safely back to Earth for analysis. These have a smooth, dome-like shape for
Feature
The success of space missions relies on components that can operate in the harshest
of conditions while withstanding extreme force and vibration. Dave Walsha, sales manager at DC motor supplier EMS, explains why linear DC servo motors are specified for unmanned space probes
help to stabilise it in flight. In some cases, the weight of the motor can be sufficient to act as a counterweight, but additional weights can be added if a higher mass is needed. Such motors must be able to operate in
the harshest of conditions – whether it’s the extreme heat of re-entry or the absolute zero temperatures of space. They must also be able to withstand extreme force and vibrations, with no loss of integrity. To provide stability in real-time, the motors
need to be able to quickly change direction. The linear servo motors in sample return capsules may need to travel along their axes up to four times a second. In addition, they must be as compact as possible and highly reliable as they can be significant in ensuring safe and efficient spacecraft operation. FAULHABER motors, supplied in the UK and
provided both reactants are present in some capacity – but if the ratio does begin to stray significantly from the ideal, then one reactant is likely to run out before the other, leaving the remainder as dead weight. To avoid this from happening, butterfly
greater aerodynamics, but with no exterior flaps, how can the capsule retain its stability and avoid spinning off course? The answer is to use linear DC servo motors within the capsule. By moving up and down the X and Y axes, the motors can help to shift the capsule’s centre of mass and
Ireland exclusively by EMS, are able to deliver to such a specification. In fact, there are already numerous FAULHABER motors hard at work in space, in applications ranging from seismometers and rovers to satellites and artificial assistants.
EMS
T: 0118 981 7391
www.ems-limited.co.uk
HOW LINEAR ACTUATORS HELPED BUILD A 3D PRINTER FOR STONE
Rotterdam-based Concr3de has developed the Armadillo White, a 3D printer for stone, which is being used in the reconstruction of Notre-Dame Cathedral in Paris. The founders of the company, architects Eric Geboers and Matteo Baldessari, proposed using the burnt remains of the cathedral as raw material to repair the damaged masonry. Needing components that would function
reliably for a long time under difficult conditions and be easily scalable, Concr3de turned to Festo when developing the 3D printer. The Festo ELGA actuator was then specified. Of benefit, the actuator can have a positive
pressure applied internally to prevent the ingress of dust, it can be supplied in long lengths, and it has a protective cover. Festo also mounted the actuator upside down so that no dust could fall into it. In
42 DESIGN SOLUTIONS APRIL 2023
addition to the ELGA axis, the control system, the Z-axis components, and the fluid supply for the binder and piping, also came from the Festo range. Using data from Concr3de, Festo calculated
the axes, gearbox, motor and control to obtain the correct inertia ratio. They also integrated a Siemens controller. All Concr3de then had to do was drag the appropriate function blocks for the communication lines from Festo's standard software libraries into the right place. Thanks to Festo’s configuration tool, only the positions to be moved had to be entered and a plan of each movement could be created. The scans needed for the 3D reconstruction
were readily available because American scientist Andrew Tallon fully 3D mapped the building in 2013. Concr3de used one of his scans to reconstruct a
striga (a bird-like demon) sculpture from Notre- Dame. The company printed a 30cm high model of the stone carving, using limestone powder and a binder, in five hours. Tests have shown that the result is not inferior to real limestone.
Festo
T: 01252 775000
www.festo.com/gb
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