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Discussion Starter · #1 ·
Among the least known of all types of guns is the research cannon. Research cannon come in a variety of calibers, from about .177 (BB sized) to 3 inches. Research cannon are primarily used to conduct terminal ballistics experiments on material samples. Chiefly, these samples are armor and occasionally they are used for other purposes, such as to study the effects of debris impacts on spacecraft.

Research cannon larger than about 20mm normally use highly compressed air for the propellant. The reasons for air propulsion are economy, safety, cleanliness, predictability and turn-around time. Economy becomes a factor when you burn vast quantities of powder with each shot. Safety is a concern when handling large quantities of powder in an enclosed laboratory. Cleanliness is a factor the same as it is for any cannoneer, you swab between shots just like folks did 200 years ago.

Air is more predictable than any powder. As a result, air yields a shot-to-shot consistency that powder cannot match. Cleaning and reloading after each shot takes time. With a 3 inch cannon you can fire six times as fast as you can with powder. Note that sometimes a research cannon is called by two different numbers. For example a 20mm cannon may take a 19mm projectile when driving bands are used. Most of my experience with research cannon has been U.S. Army owned 20mm, powder fired. I had the option of converting to air, but at heart I'm a powder burner.

Research cannon can be highly versatile. With a 20mm gun you can load for muzzle velocities slower than 500 feet per second (fps) or faster than 4400 fps. This is because reseach cannon are normally smooth bores. It is desirable to fit the barrels within pipe sleeves equipped with adjustment bolts to remove barrel sag or bending. Research cannon are modular and can be reconfigured at will.

The projectile can be of any shape or length and uses driving bands or a sabot to fit the bore. Each projectile is custom machined for the experiment at hand. The projectile may be a model of a shell or a saboted rifle bullet.

The cannon is customarily fitted with a long, steel target chamber. The target (tested piece) is mounted inside of the target chamber. The reason for fitting a sealed target chamber is to allow the removal of air from both the cannon and target chamber. Removing the air lessens the chance that the projectile will yaw over the brief distance from muzzle to target. The target chamber also protects the researchers from debris hurled at high velocity by the impact. On occasions, sections of railroad cross-ties that I used to brace the targets were obliterated by the kinetic energy of the projectile. A few times only toothpick sized pieces remained.
 

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Cool, can you describe some of the projectiles and targets you've used?

This has been very interesting so far...

:devil:
 

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Discussion Starter · #3 ·
I've used pointy, conical bullets machined from steel and polycarbonate. I designed a round nose (hemispherical) bullet with a deeply recessed middle that has been used for testing composite armor. It had to be extremely stable from a smoothbore, yet attain velocities on the high end. I redesigned the driving band grooves on a series of cylindrical bullets that were used for damage wave tests on composite armor. All of these were steel or polycarbonate.

The best bullet shape for reading what is happening inside of the armor on impact is the wadcutter (cylinder). It gives the cleanest signal.

I designed and conducted "flyer plate experiments" for damage wave tests on composite armor, too. The flyer plate thing is where you place a larger-than-bullet-diameter metal disc between the bullet and the target. It simulates a large, but short wadcutter. Then you fire the bullet at maximum velocity into the flyer plate, causing it to strike the target. It gives you a more readily distinguishable damage wave signal.

I have designed and tested saboted rifle bullets on composite armor.

I have tested a variety of small arms on composite armor.

The barrel wall thicknesses on these cannon are over one inch thick.

I have shot composite armor samples at such high velocities that the matrix was pulverized and flowed out, leaving only the fiber weave.
 

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for measuring the damage waves in the targets, what kinds of sensors are used?

Do you use transducers, high speed phototagraphy, or piezo strips (might not have the correct name, but basically IIRC, strips of material that either generate an eletric charge or change their resistance when force is applied to them)?

All of this stuff is interesting.

:devil:
 

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I find that the technology and techniques for measuring results can be as interesting, or more, than the actual tests - sometimes.

When I was in college, I had a job where I built particle detectors for use at a particle accelerator. It was fascinating, and amazingly simple how the detectors were bult.

Basically we constructed a huge frame that was composed of many layers. On the inside of a frame layer we placed wires accross the opening. Each wire was placed using a custom built precision measuring machine. there were two types of wires, and they alternated: a sensing wire and a high voltage wire.

Each layer of the detector had the wires running in one of three directions: horizontal, vertical, or on a 45 degree angle. (giving us X,Y, and U coordinates - couldn't do Z as it was not possible to have wires running between frames)

The ends of the frame were sealed using mylar. the detector would then be connected to a camac rack (computer interface) with several hundred coax cables. The detector was then filled with a mixture of argon and ethane gas.

This mixture had a really interesting property (other than being flammable), namely that ions of this gas had a constant drift rate.

so, how the detector worked was that particles would pass through the detector, ionizing some of the gas molecules. In turn these ions would create a circuit between a voltage wire and a sensing wire.

You could determine the path of the particles based on which wires showed voltage. All it took was a little geometry (and a very accurate accounting of the postion of every single wire.)

:devil:
 

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Dang!Gbullet,your posts just keep getting more interesting.I have a picture in my minds eye about building a shoulder fired,air propelled,saboted,.30 cal rifle.
I can see it being expensive,dangerous,odd,expensive,heavy,& expensive.

It could be kinda neat though...

Please keep the posts coming!Thanks!
 

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41mag said:
Dang!Gbullet,your posts just keep getting more interesting.I have a picture in my minds eye about building a shoulder fired,air propelled,saboted,.30 cal rifle.
I can see it being expensive,dangerous,odd,expensive,heavy,& expensive.

It could be kinda neat though...

Please keep the posts coming!Thanks!
I'm thinking, some air cylinder tubing, a couple fittings, the right valves, a little nitrogen (or compressed air), and you've got a really cool device.

Though I wonder where it would fall in terms of the BATF's views on things...

:devil:
 

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Aslan said:
I'm thinking, some air cylinder tubing, a couple fittings, the right valves, a little nitrogen (or compressed air), and you've got a really cool device.

Though I wonder where it would fall in terms of the BATF's views on things...

:devil:
I wonder how much pressure would be required.
I was thinking more along the lines of a 200gn projectile @ around 5000fps +.

I've seen a site where a fellow makes big bore air rifles at least .40 cal.IIRC he used a "scuba"type valve/filling arrangment.IIRC the velocities he worked with were comparable only to black powder though....
 

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Discussion Starter · #10 ·
CAV said:
G,

Are you doing DOD/contracting or private research?
My work with research cannon was financed by the U.S. Army and U.S. Navy.

Currently, I work as a consulting engineer. At this time, my ballistics research relates to my patents and is self-financed.
 
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