Poly students launch ping pong ball faster than speed of sound

They call it the Ballistic Accelerator Device (BAD).

It can launch a ping pong ball faster than the speed of sound and with such force that it can punch a hole right through a ping pong bat.

And it does this using just compressed air.

Put together by three Singapore Polytechnic (SP) mechanical engineering students as part of their final-year project, the BAD broke a Singapore Record last Wednesday by firing a ping pong ball that reached a speed of 428.6m/s, or Mach 1.25, which is about how fast an F16 fighter jet can fly close to sea level.

This is the first device in Singapore that can fire an object faster than the speed of sound without the use of pyrotechnics or combustion, said Singapore Book Of Records president Ong Eng Huat.

"While there may be other devices that can launch projectiles faster than the speed of sound, none has used air pressure alone," he said.

Singapore

Wind beneath his wings

Jun 13, 2018

Mr Leong Ying Wei, 32, a mechanical and aeronautical engineering lecturer at SP, was the one who suggested the idea of the ping pong gun to his students Daryl Heng, Kendrick Hu and Douglas Wong.

He was inspired to do a project like this after coming to know of a similar project by graduate students at Purdue University in the US.

SUPERSONIC

Mr Leong, who supervised the team, said the BAD is essentially an extremely high-powered air gun that uses high-pressured air combined with the low resistance in a vacuum to accelerate the ping pong ball to supersonic speeds.

Plastic sheets are placed between the two main tubes to let air pressure build up on one side before breaking, letting the pressurised air propel the ball.

It took the team three months to put together the first working prototype of the BAD. They said their biggest challenge was picking the right materials for the plastic sheets.

Mr Douglas Wong said: "The material cannot be too weak, but also cannot be too strong, or it will not burst when the air in the vessel has reached a high-enough pressure."

After two days of testing, the team succeeded.

"We never thought that an object as light as a ping pong ball could have the power to destroy something as hard as a ping pong bat," the group said.

"We were thrilled and also extremely satisfied when we succeeded."

During the record-breaking attempt last Wednesday, the team used pillows to catch the supersonic ball after it was launched.

With a bang, the ball tore through the pillow case and buried what was left of itself within the cushion, causing the entire target set-up to topple off the table.

Mr Leong said there are many potential applications for a device like this in the military sector, highlighting that this would be ideal in launching Unmanned Aerial Vehicles at high speeds.

While the BAD may sound like a really cool science project, he warned that the experiment should be conducted only in a controlled environment.

"When at object travelling at that kind of speed hits a vital organ, it can kill. Do not try this at home," he said.

BY THE NUMBERS

428.6m/s

The speed at which a team of three Singapore Polytechnic mechnical engineering students shot a ping-pong ball, breaking a Singapore Record

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