Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: When does recoil occur???

  1. #11
    Join Date
    Dec 2004
    Location
    Sherman's Kitchen, GA
    Posts
    980
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas

    Re: When does recoil occur???

    While “recoil” is certainly related to Newton’s third law of motion that for every action there is an equal and opposite reaction, recoil is actually the phenomena which occurs when the expanding gas column which propels a projectile inside a cylinder suddenly clears the end of the cylinder and the gas rapidly expands, and it is this force that once it has transferred to the barrel causing it to move in the opposite direction which we call “recoil.” Therefore, it may be observed that a shorter barrel produces a far greater recoil than a does a longer barrel because the shorter barrel has less internal volume for the gas to expand and is thus under a greater pressure when it vents than does a longer barrel which because of its greater volume contains a lower pressure when it is vented (i.e. when the projectile clears the muzzle). Until this point, the internal expansion of the gas does not translate into any measureable motion within the barrel, and if any part of the explosive chain could be felt, depending on the relative mass of the barrel it would perhaps be the movement of the projectile's mass within the barrel affecting the equilibrium or balance of the barrel, but not causing or contributing to any kind of recoil force, least not until the projectile escapes from the cylinder. So it is the internal gas pressure at the moment it escapes and expands from the barrel rather than the mass of the projectile that equates to the force of the recoil. The weight (i.e. mass times gravity) of the projectile is but a small portion of the total recoil force. Theoretically, if a barrel was long enough to compensate for the full volume of the gas pressure, the forward motion of the projectile would literally stop and there would be no recoil.
    First Cousin (7 times removed) to Brigadier General Stand Watie (1806-1871), CSA
    1st Cherokee Mounted Rifles | Principal Chief of the Cherokee Nation 1862-66

  2. #12
    Join Date
    Dec 2004
    Location
    Sherman's Kitchen, GA
    Posts
    980
    Region:
    Deep South - Georgia, Louisiana, Tennessee, Mississippi and Texas

    Re: When does recoil occur???

    Sir Alfred George GREENHILL, Kt., F.R.S. (1908) Notes on Dynamics: For the Advanced Class of the Ordnance College, Woolwich.

    http://books.google.com/books?id=nO_mAA ... &q&f=false

    Page 24 addresses “long recoil” while on page 38 illustrates the calculations involved in working out the ‘problem of recoil when the gun in its carriage or cradle is mounted on a railway truck or in a boat, of total weight M-lb, and checked by a buffer or frictional resistance of R-lb between the cradle and truck or boat, ignoring the weight P of the powder charge.’

    As noted ‘the experiment can be made also with a gun suspended as in (12), firing at close range at the ballistic pendulum. Supposing, first, that the resistance does not come into action till the shot has left the muzzle; the gun will begin recoiling with velocity (w/W)V, and finally, when the recoil has ceased, the whole system M will be moving with velocity (w/M)V, the time occupied in the recoil and the length of recoil will be [see equation] during which the truck or boat will move W/M of this length.’
    First Cousin (7 times removed) to Brigadier General Stand Watie (1806-1871), CSA
    1st Cherokee Mounted Rifles | Principal Chief of the Cherokee Nation 1862-66

  3. #13
    Kevin Tinny is offline
    Team:
    Tammany Regiment, 42nd New York
    Member
    13667
    Join Date
    Apr 2014
    Location
    North Florida
    Posts
    573
    Region:
    New England - New York, Connecticut, New Jersey and Massachusetts
    Hello and please forgive replying to an old Thread:

    Saw McAuley's post and thought about it and the "When Does Recoil Occur?" question.

    For me, the question would be:
    Does the gun MOVE WHILE the bullet is IN the bore ("barrel time")?
    This might be different from the technical "recoil" aspect.

    I like John Wells' pebble under the wheel suggestion.

    NOT to disagree with McAuley, rather to learn, my experience with rifles off a well setup bench is that with a correct, uniform sight picture, the slightest bit of variation in one's body resistance will move the shot because of "barrel time". So my conclusion is that the gun moves WHILE the bullet IS IN the barrel.

    McAuley IS the expert and I respect that.

    What am I missing here, please? Thanks.

    Kevin Tinny
    Tammany Rgt, 4w NY 13667

  4. #14
    Des is offline
    Team:
    1st Regiment Virginia Volunteers
    Member
    12385
    Join Date
    Mar 2008
    Location
    Yorktown, Virginia
    Posts
    202
    Region:
    Tidewater - Virginia and North Carolina
    From the high speed cameras that filmed our cannons firing it definately looked like the projectile was out of the barrel before the cannon moved
    Des Donnelly
    1st Regiment Virginia Volunteers
    12385

  5. #15
    Kevin Tinny is offline
    Team:
    Tammany Regiment, 42nd New York
    Member
    13667
    Join Date
    Apr 2014
    Location
    North Florida
    Posts
    573
    Region:
    New England - New York, Connecticut, New Jersey and Massachusetts
    Thanks on the high-speed info:

    I recall a UTUBE guy with ultra high speed camera footage of cannon firing.
    Search UTUBE for: Try "Smarter Every Day" "Cannon Shock Waves..."

    In every sequence that is clear enough, the first thing out of the muzzle was a large "initial" cloud of gas and then the projectile in the rear of the initial cloud. Then the main cloud of FIREY colored gas and particulates were last. If gasses beyond the muzzle contribute to recoil and a small amount blow BY the projectile IN the bore and seem to exit first ....?

    Am still unsure about why one must "hold" a gun the same if the bullet is gone before gun moves.

    I suspect there is a technical difference in physics and dynamics involved.
    Hopefully brother McAuley can help.

    Very respectfully,
    Kevin Tinny
    Edited for spelling.
    Last edited by Kevin Tinny; 01-10-2020 at 09:43 AM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •