Friday, July 11 14:36:21
The European Space Agency has contracted engineers at University College Dublin (UCD) to find new ways to reduce vibrations during lift-off in future launcher designs.
The E250,000 contract will see the UCD engineers design a "control algorithm" which can tell the launcher's rocket engines and thrusters how they should most effectively be fired and controlled to absorb vibrations on their journey out of the Earth's atmosphere and into space, UCDinnovation said today.
Too much vibration can damage the launcher's structure and certainly reduces "payload comfort". The payload could be, for example, supplies for the International Space Station, or satellites for communication, for Earth monitoring, for global positioning, or large astronomical telescopes. The less vibration such delicate devices experience the better.
Reducing vibrations also helps to maintain the finely calculated trajectory of a launcher from lift-off into orbit. Any departure from this course must be corrected, usually by steering the rocket motors, but this reduces the main thrust forward and so consumes more fuel.
Dr William O'Connor, UCD School of Mechanical and Materials Engineering, University College Dublin, who will lead the research, told UCDinnovation, "Keeping launchers on course when immensely powerful engines are violently shaking the structure is a complex problem. This is made even more complex when you consider that there are tonnes of liquid fuel like liquid hydrogen and oxygen sloshing around inside a relatively delicate structure."
To lift-off, overcome the Earth's gravity, and enter orbit, launchers must quickly reach a speed of 28,000 km/h from a standstill. This requires an immense amount of fuel. They also need enough additional propellant to complete their mission.
At lift-off, about 90pc of the weight of the launcher is fuel. About 90pc of the thrust coming from burning the fuel is used just to lift the fuel itself. All the other weight, including the launcher structure, rocket motors, control systems, communication systems and of course the precious payload, must fit into the remaining 10pc.
"The weight calculations are precise and literally every gram counts. If the ratio of thrust to weight from the chemicals in the fuel was a few percent lower, we would be stuck on Earth," explains Dr O'Connor.
With designs tending towards lighter and lighter structures, launchers are becoming even more prone to vibrations and oscillations.
"Our work aims to design more stable launchers, giving improved performance and a smoother ride than is currently possible," he added.
Dr David McKeown, a UCD research engineer and partner on the research programme said, "Ultimately, it is all about safely delivering the payload into space with the most precision and minimum fuel consumption."
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