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Evan
09-10-2005, 12:18 PM
I watched a very interesting show last night on the history and development of field artillery. In one part of the show they showed the flight of various full scale rounds to show the effects of the shape of the projectile as well as the effect of rifling on the stability in flight.

Somehow they followed the shells with a camera in realtime from beside them with the landscape flying by in the background for long periods of time. These were not wind tunnel tests. How the heck do they do that?

maddog
09-10-2005, 12:35 PM
Smoke and mirrors.

topct
09-10-2005, 12:45 PM
They used a twin barreled cannon. It fired a test round out of one barrel, and a special camera out the other.



------------------
Gene

JRouche
09-10-2005, 12:45 PM
My guess is it was simulated. I worked on a cannon that had roughly 3000 feet per minute muzzle velocity. That is about 2000 MPH. Say the round traveled for 15-20 miles it would take an aircraft flying at 2000MPH. What was the age of the film? JRouche

mochinist
09-10-2005, 12:53 PM
They gave this guy a video recorder.
http://www.gottawiz.com/images/Comics/DC/Superman/superman%5B1%5D%5B1%5D.gif

meho
09-10-2005, 01:01 PM
Here ya go,

I have a friend that recently retired as a weapons developer for the USAF. He kept me informed as much as he could about these things and where to find them.

The "easy way",
Synchroballistic photography overcomes both the problem of synchronization and exposure time by making the image of the object pass over an open slit while at the same time the recording medium passes below the slit at approximately (or exactly if possible) speed as the image. Since in this manner the image does not move with respect to the film a sharp record can be secured even at relatively long exposure times, these being a function of the width of the slit and the rate of film movement.

http://www.rit.edu/~andpph/text-strip-synchro.html


The "hard way",
Ten tracking telescopes produce still photographic output from test events. Seven of the units are ME16 Newtonian telescopes with 16-in. apertures and 117.5-in. focal lengths. Four of the units are mobile and three are mounted at fixed sites. The largest range telescope is an LA24 Newtonian with a 24-in. aperture and 235-in. focal length and is a fixed unit. Both the 16-in. and 24-in. provide high resolution resulting in very clear images at long distances.

The SM2/SM3 are two smaller telescopes with 12-in. apertures and 60-in. focal lengths. Both have multiple cameras and are mounted on pedestals with a high performance slew rate of 50 degrees per second. The SM3 is also equipped with an autotracker.

Two additional camera and tracking stations each mounting an automatic 4E camera with interchangeable 6-in. and 40-in lens. The 35-mm cameras can run from one to 360 frames per second.

All of the optical trackers have the Tracking Vector Translation Systems (TVTS) installed which receive target acquisition and focusing data via UHF link from each operating radar station to drive the tracking mounts.

Tracking Vector Translation System
The Control Center multiplexes the information from the radars together and distributes the data over a single RF carrier to all radar, telemetry and optical tracking stations in operation.

TVTS modules at each tracking station provide focus information for optical trackers and space points for radars.

http://www.serve.com/mahood/nellis/ttr/ttrbook.htm

James

lynnl
09-10-2005, 01:14 PM
Was that a recently made film? ...or older?
I can't remember his name, but there was a professor, who I'm sure is dead now, who pioneered much of the difficult/incredible photography techniques. I'm pretty sure he started at the Univ of Nebraska, and later moved on to MIT.

AIRC he was the first to capture a speeding bullet in flight. Also falling water droplets, and a lot of other incredible photos and film shots.

Not to divert the thread topic, but for any who haven't seen it, I recommend seeing the documentary film "Winged Migration". It has fantastic scenes of birds (mostly geese) in flight. Of course that's a bit slower than an artillery shell. But still fascinating.

Evan
09-10-2005, 01:48 PM
High speed photography was professor Edgerton. He developed the cameras for taking pictures of atomic weapons as well as high power strobes that could take flash pictures from 20,000 feet.

This is a very recent film showing among other things every development from the original banded wood stave black powder cannons to the latest M777A1 155M ultralightweight field howitzer which is nearly all titanium. They actually made some of the weapons on the show in a well equipped shop and also showed the forging of barrels as well as the lathes and turning of the barrels. They also showed a foundry actually casting a bronze cannon about like a 12 pounder.

The photos of the shells in flight were definitely not simulations. What meho describes as the "hard way" must be what they did. You could actually see the shock waves off the front of the shells in flight. This wasn't a low budget show.

Buckshot
09-11-2005, 12:32 AM
.......Not the same thing but if you have a slight breeze to clear the smoke, or as a close bystander you can track the flight of a 58 cal Minie'. When shooting long range muzzle loading match rifles (800, 900, 1000 yds), with a high quality scope you can watch the slug for quite some distance.

Shooting cast lead from a Savage M112, 223 with a 24X scope, it was intrigueing to watch the bullet appear in the scope on it's ballistic arc to the target. Then a fraction of a second later disappear and a tiny hole appear on the paper.

Rick

BillH
09-11-2005, 12:45 AM
OK, Sounds awsome, I always wondered how some of those nature shows did that with insects, like bumble bees flying around and landing on flowers.

bobbybeef
09-11-2005, 03:10 AM
Ah gunners,
Taking the picture is simple;hitting the target is another thing altogether.
Bobby.