SpudFiles

Yeah, actually looking at the frames, it does look like the blades are moving much faster during one half of the rotation, originally I though I'd taken the picture at an angle making one side look bigger in perspective.

My brain is fine with distortion due to side to side scanning along a line (like a flat bed scanner), and I can quite easily picture what a clock would look like too, the first GIFs are crazy though

I remember being really bored a few years ago and adjusting the speed of a PC fan, in order to make another look like it was static when looking through the spinning blades.

Could we repeat the test with a long (possibly bulb) shutter speed and a flash? A strobe light would provide interesting effects, but I'm not sure mine has much power. I don't have anything with which to shoot a die at the moment either. vivitar 283's are cheap and can be as short as ~1/40,000

New videos...

[youtube][/youtube]

Edited by jrrdw.

Just bought an FH100 and a kodak Zi8 (720p @ 60fps) for a steal on Ebay... Can't wait to get some footage of 10 gallon throwing canned foods and beverages at appliances

Interesting high speed video:
[youtube][/youtube]

Now that couldn't have been better, shame the turkey wasn't going that fast though.

I've just been to a corrida, while I'm not a fan of the spirit of the event, I respect it as a tradition. I've got quite a lot of high speed footage, so unless anyone objects on animal cruelty grounds I'll make a youtube compilation.

Due to the subject it may be best to do the video but not directly link to them. Those interested could simply look at other videos on your youtube channel. My lighting a campfire video would be like that. It is there for those who want to find it.

Ontopic, I'm working on a burst mode high speed strobe that will flash a burst of very precise flashes at 1,000 flashes per second. It would be to clock marshmallows. I'm looking at bursts selectable from 2 to 9 flashes for use with either a film camera on the Bulb setting or a digital on a manual exposure of several seconds.

One of the guys I work with is claiming supersonic marshmallows clocked with a shooting chronograph. I'm looking to verify the results with a high speed strobe shot.

The basic circuit is a series of modified disposable camera strobes triggered by a CMOS decade counter, a 4017, driven by a crystal time base at 1KHZ. The count would be held in reset until a wire break releases the enable starting the firing the string of flash units.

For a lower intensity flash and a shorter flash duration, the flash units would have the original photoflash cap replaced with mylar caps of a much lower value. The flashes can then be placed closer to the subject and the total of the flashes could add to one proper exposure of the scene with the projectile illuminated in flight by the string of flash units. For near SOS they could be strung out about a foot apart. This should give good projectile illumination along the shot path.
The resulting photo would look something like this;

Technician1002 wrote:Due to the subject it may be best to do the video but not directly link to them. Those interested could simply look at other videos on your youtube channel.

Posted on photobucket, PM for links.

Ontopic, I'm working on a burst mode high speed strobe that will flash a burst of very precise flashes at 1,000 flashes per second.

1000 frames per second is good enough to see medium sized sub 500 fps projectiles from the side, you should get good results.

[youtube][/youtube]

I am looking to clock mini and regular size marshmallows. If the other guy's results are valid a 1 inch sprinkler valve coupled to a 1/2 inch barrel can launch mini marshmallows just over SOS on compressed air at 150 PSI. I am looking to validate the results or disprove it. He is clocking mini marshmallows at nearly 1400 fps.

Technician1002 wrote:I am looking to clock mini and regular size marshmallows. If the other guy's results are valid a 1 inch sprinkler valve coupled to a 1/2 inch barrel can launch mini marshmallows just over SOS on compressed air at 150 PSI. I am looking to validate the results or disprove it. He is clocking mini marshmallows at nearly 1400 fps.

Surely you need not a practical explanation to try validate those claims but simply theoretical physics? I wouldn't have thought it possible to send anything like that supersonic with those specifications let alone that far past supersonic.

What are the diameter and weight of mini marshmellows? I'm not familiar with them.

They are just under 1/2 inch in diameter.

http://www99.epinions.com/reviews/Kraft ... Jet_puffed

looks like there are about 571 of them in a 10.5 oz bag so they don't weigh much.
http://wiki.answers.com/Q/How_many_mars ... in_one_bag

I figure some good HS strobe photography will see if those claims are out of line.

I do have some HS video of my larger cannon showing what appears to be a pressure front traveling about 15 inches in 1 ms. It may be possible.

I ran some numbers in GGDT and 800fps seems like a more realistic number although a valve with a CV of around 18 could definitely achieve such velocities. A 1" sprinkler valve has a CV of around 6.5 I believe.

I share MrC's scepticism, exceeding mach 1 with a relatively slow (compared to burst disk) valve and shop pressures sounds a bit unrealistic, even with a light projectile.

It would be interesting to quiz your colleague on his exact chrony setup. A strobe light and camera capturing the projectile against a graduated scale would be a much more reliable indicator of true velocity.

I do have some HS video of my larger cannon showing what appears to be a pressure front traveling about 15 inches in 1 ms. It may be possible.

can we see the vid? sounds interesting.