Recoil and my concern.

[Blaster]

>>Finally, with the Assault Weapon Ban to expire this coming week, looks like I can remount the bayonett lug back on my cannon.  


Yea.  I think I remember a CW mortar with bayonet lug, folding stock, separate pistol grip, muzzle brake and removeable 30 shot mag too.

[Cat Whisperer]

blaster -

OOPS - I aimed for the 'QUOTE' and hit the 'EDIT' button and TORE UP your post.  SORRY.

But, regarding recoil.  With the mortars, at about 45 degree elevation, the movement is minimal - a few inches back when on wet grass.  If you crank it down to 15 degree elevation then the whole rig will slide back a foot or so (flat base 100 LB + ), if on wheels someone who does cannons can respond with experience.

Having a good backstop is a must.  If you're shooting a projo down range it's more than just OOPS if something goes wrong.  Cement filled beer cans and 7.5 lb pieces of 4"pvc concrete filled cylinders tear limbs off trees with resound.

[Blaster]

OH thats OK, CW, that post was probably a little on the lengthy side anyhow. At any rate, I'm pretty confident in my mortars remaining in their positions, it's the cannon that I'm mainly concerned about.  My original inquiry was that I was wondering if a CANNON projectile is normally well out the bore and heading downrange before the cannon begins it's recoil movement.  It would seem that the initial recoil would have little influence on the of flight of the projectile.  Any thoughts y'all ??
Thanks, Blaster (Bob in CO)

[Cat Whisperer]

There will be some difference in impact depending on how solid the cannon is.

First let's look at movement.  At the moment of firing both cannon and ball are at rest.  In milli or micro seconds the ball is moving and the cannon is moving, however the cannon is moving slowly and the ball at high speed.  How well supported the cannon is will affect the point of impact, but very little compared to where the cannon will hit if not repositioned.  

Second, look at digging in the piece.  With 105mm and 155mm howiters, the trails are dug in to provide a solid base.  Before each shot the sights are checked and the azimuth and elevation are adjusted.  After the first few shots not much adjustment is needed.

[Double D]

Before, firing at rest, note position of the ropes.



Firing.


It is my experience that the Naval guns will flip on the back if not restrained.

I don't have a firable field gun right now,  and no pictures to show of the ones I had firing, but they tend to to jump and slide back on there tail skid.

[Calamity Jane]

My 1/3 scale 6 pounder weighs about 85 pounds. It fires a 1" ball weighing 1,400 grains. On smooth level ground (grass), the cannon recoils about 18" to 24" straight back.

Physics dictates equal and opposite reactions so the mass times the velocity for the cannon (less frictional losses) must be equal to the mass times velocity for the ball when shooting level.

Though I have not chronographed my cannon balls (yet) the best minds at the range are estimating 1200 FPS.

Of course, when shooting a mortar, a lot of the force of the shot goes into driving your carriage into the ground!

[John N]

A 1400 grain projectile at 1200 fps generates about 4500 foot-pounds of muzzle energy, equivalent to a very heavy high-power rifle round. It's certainly nothing I'd want to put my shoulder behind.

I've been looking at a golf-ball sized cannon. A 1.67" lead round ball weighs 7000 grains (or 1 pound). At the same 1200 fps velocity, that load would generate in excess of 22,000 foot-pounds of ME!

Going up the scale to a 3 pound ball, ME is a whopping 67,000 ft-lbs.

A 12 pound ball at 1200 fps generates 268,000 ft-lbs of ME. Now that's exciting.

[Double D]

One of the safety rules says don't stand behind the cannon when firing. Now you under stand why.

[Max Caliber]

Blaster: Back in the 70's we shot artillery at major muzzleloading matches around the state of Florida until they put a stop to it because we were causing damage to the backstops. During this time, we experimented with improving accuracy. It is generally known that when fired, some recoil occurs in a cannon before the projectile leaves the barrel. It is therefore very important that all looseness be removed from the various parts of the cannon. The barrel trunnions should fit their sockets snugly and the carriage should be constructed tightly so the recoil will be transmitted evenly to the wheels from shot to shot. One of the most important items is that the wheels should fit the axle without excessive wobble or end to end play and should turn on the axle with the same resistance - one wheel should not be tighter than the other. Cannon shooting is much the same as rifle shooting. You won't get consistent accuracy with loose stock screws and holding the rifle differently from shot to shot.

You will never get rifle accuracy from a conventional style cannon but you can improve it so it will shoot with more consistency. generally, accuracy goes down with the reduction in scale. There's a point where recoil gets all out of proportion to the weight on the cannon. Accuracy can be improved somewhat by using close fitting channel iron or wooden troughs for the wheels and trail to run in when being fired.

[Cat Whisperer]

Though I have not chronographed my cannon balls (yet) the best minds at the range are estimating 1200 FPS.

A one inch lead ball would take the chrono to at least the 50 yard line.

[Cat Whisperer]

It is therefore very important that all looseness be removed from the various parts of the cannon.

I saw one mortar where the trunion was glass-bedded, as rifles are, for just that reason.