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# Accelerating a Mass with pneumatics

## Accelerating a Mass with pneumatics

(OP)
Hey all,

Not sure I am posting in the right forum, but here it goes.

I need to simulate a mass falling from 10 meters, but only have about a meter of height to do it in. Therefore I need a method of accelerating the mass to a certain velocity, and then release the weight halfway through its travel so the mass is in free-fall at the time of impact.

The first thought that comes to mind is a pneumatic system with a magnet as a release. As long as the stroke of the piston is shorter then the 1 meter height, it would essentially give the weight a "boost" at the beginning of its drop. However i do not know if this is possible with pneumatics. Has anyone heard of a piston that would be capable of this kind of velocity? it is a 7 lbs mass.

OR if you have another method of how to accelerate a mass with these conditions, id love to hear about it.

Thanks,

Wes
Replies continue below

Gunpowder.

Fe (IronX32)

### RE: Accelerating a Mass with pneumatics

Pnuematics for motion control are typically not a good ideal.  Repeatablity and control using air (compressible gas).  If you want to accelerate a mass, maybe using a timing pulley and timing belt arrangement might be better.  This hooked to a motor with variable speed drive, might do the trick.  If you need more control and precision with acceleration then hook the system to a servo drive.

Rich....

Richard Nornhold, PE
http://www.personna.com

### RE: Accelerating a Mass with pneumatics

A flywheel?

Since you will be accelerating faster than gravity you would not need to release only at the bottom of stroke.  I was thinking of a punch press design.  You may need the ram to quickly reverse stroke and get out of the way of any bounce.  Have the down stroke of the ram trigger a mechanical release of the object at begining of stroke.  Vary the speed of flywheel as needed to tweak impact velocity.

Or just cut a hole in the roof....

Barry Payne, Titular Despot Emeritus

### RE: Accelerating a Mass with pneumatics

I'd just use a big compression spring with a pin release. Easy, adjustable (put a screw behind a plate at the top), and cheap.

"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." -Scott Adams

### RE: Accelerating a Mass with pneumatics

(OP)
Thanks all for the posts! Ill look into them further.

### RE: Accelerating a Mass with pneumatics

Consider a simple lever arrangement.
Pin the lever at one end and locate a weight of ten times (or 100 times if this varies with the square ? ) at 10% of the lever length from the pin. This will produce a 10 g acceleration. Provide a strong "stop bar" at the end of the lever at the opposite end from the pin at the height tou require for the "free fall" to start.

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