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Schlieren picture of how silencers work

How silencers on guns work has come up on this list several times and opinions have been "diverse". There's an article in the January-February

2006 "American Scientist" on modern versions of Schlieren photography (with a good clear explanation of how they work, which had always eluded me) that has some great pictures, including what a silencer really does. On p. 30 of the magazine there is a picture of the same .45 pistol with and without a silencer. Pretty impressive. Essentially what a silencer does is suppress the supersonic shock wave that comes off the end of the muzzle into a narrow cone, that sounds more like a gas jet hiss.

It's also available on line if you're quick (I think it's only up while it's the current issue). Go to

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, pick "High Speed Imaging" and jump to page 5. Actually the whole article is worth reading and the pictures are great. The .30-06 picture on the first page is awesome.

Jim

Reply to
Jim McGill
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Ouch. That site requires a login, it lets you pick one, then it won't take that for the actual article.

Grant Erwin

Reply to
Grant Erwin

I didn't log in. Just clicked on the article and viewed away...

Reply to
Clif Holland

jk

Reply to
jk

Reply to
Grant Erwin

In my many years of working at NASA, I enjoyed using the world class Schlieren system at NASA Glenn's 8x6 Transonic Wind Tunnel. The system was built in the early 1950's and I believe it was the biggest in the world at that time (it may still be).

It used 40" diameter front surface, concave, mirrors to place a 40" light path through the windows of the test section of the wind tunnel. The mirrors were mounted on what looked like converted lathe beds so they could be translated back and forth in two directions as well as tilted.

The light source and the knife edge were remote controlled in all three axis, and in addition, the knife edge could be rotated around the focused beam to place the cutoff at the optimum point. Tuning it was quite an artful task!

We converted it to a rainbow Schlieren in the 1970's. This system replaces the knife edge with a translucent film which has a standard color spectrum on it. This allows the image of the shock waves to take on colors which correspond to their density.

Dennis

Reply to
DT

I've always been fascinated by Schlieren photography, and high-speed photography. These guys have combined the two! Fantastic!

Jon

Reply to
Jon Elson

Thanks, Jim. That is a great article! I clicked the link for a printable version and then copied the resulting URL and pasted that onto an email to a couple of gun nut friends.

Paul

Reply to
pdrahn

I have a pretty good idea of how Schlieren photography works ( I recommisioned the camera here at work, replacing the old 9" camera with a ccd). The camera has a light source that has lines that block 1/2 the light. The camera has a precisely located matching grid that overlaps the other grid by

1/2. The straight line light path only allows 1/4 the light to get through. In our system the light source grid is ~ 5' dia and the lines are ~3/8" spaced about 1/4" apart. The camera is focused at the model and through the camera grid, you don't see the grid at all. The way it works is that different air pressures defract light different amounts, so areas of different pressures get either more light or less light making it throught the grating.. Pat
Reply to
Pat Ford

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