Further consequences of Thrust Vectors

[Lazarus]

Intense thread on the subject of recoil. Obviously, it is not that intuitive for everyone. I guess that's why the world had to wait for Newton. I re-read Kuhnhausen's thrust vector explaination and it is obvious to me that he was having trouble at that point. The language gets vague and no wonder, when you have to make up some magic forces to get your ideas to work. Just after the thrust vector hypothesis, I came across another section that appears incorrect. This section deals with the linkdown phase and appears in Illustration 5. Here is the questionable part:

"...vertical lug disengagement begins after the barrel locking lugs have reached max rearward position..."

If I understand this statement, he is saying that the vertical movement (unlocking) of the upper lugs begins after the barrel lower lugs have struck the VIS. Well, folks, if that is the case then we have described a major barrel crash and the result would be a trashed barrel and possibly a trashed slide. Anyway, it seems like the thrust vector theory may have led to yet another fanciful conclusion about barrel unlocking.

-Lazarus

[Hawkmoon]

Kuhnhausen has a few things wrong in his discussion/analysis of barrel retraction and unlocking

[1911Tuner]

Very true, Lazarus. If you'll look in Volume 2, Page 124 at the top...you can see another mistake in the diagram where he refers to the barrel chamber face as the recoil face. Again...when we start to understand that the barrel doesn't recoil...doesn't move backward until the slide pulls it...we see that this just can't be.

Kuhnhausen's shop manuals have long been considered the 1911 bible...and I use them for reference often...but many people simply accept what is contained therein as though it were the Ten Commandments. A little careful study and a full understanding of exactly how the gun works will reveal the mistakes. Trying to point them out and explain them however, is akin to blasphemy for some...often sparking some pretty intense flame wars and even personal hard feelings...but I will endeavor to persevere. ;)

One thing that I've often said is that, while Kuhnhausen is a very sharp gun guy, he ain't exactly Papa Hemmingway when it comes to the written word.
I suspect that some of his mistakes aren't so much that he didn't know...but that he didn't convey it clearly and missed it on the final editing. Just look at how long it's taken me to get the recoil thing 'splained. :D

For those who missed the other thread...Here it is:

Bullet<==Bang==>Slide&Barrel-->{linkdown}-->Slide

The slide starts to move before the bullet exits...not AFTER the bullet exits, as per Kuhnhausen's Balanced Thrust Vector explanation.

[Hawkmoon]

And because the barrel sits atop a pivoting link that is at 90 degrees of verticality when the pistol is locked up, simply geometry (this has nothing to do with thrust vectors or conservation of energy, just simply geometry and mechanics) dictates that the rear of the barrel begins to drop down (which also means begins to unlock) as soon as the slide and barrel move backward relative to the receiver. Because if the nature of arcs and angles, the vertical component of the unlocking increases exponentially the farther back the slide & barrel move ... but the unlocking begins the instant the slide and barrel begin to move.

Again, this may be another example of Kuhnhausen's lack of skill with the written word. He may have meant that unlocking is not completed until the barrel has seated against the stop surface in the receiver ... but that ain't what he wrote.

[1911Tuner]

Look at it again Hawk...The link isn't dead vertical when the gun is in-battery...at least it shouldn't be. It's actually a bit overcentered by about 3 degrees or so. If you pull the slide back slowly and watch the barrel, it doesn't start to drop until the slide has moved a little. Nominally, .100 inch, but it can move as much as .125 before the barrel reaches the linkdown point.

The link can't disengage the lugs vertically until the bullet is gone. There's too much horizontal pressure. At least, it can't do it without damage to the link, the pin, the slidestop crosspin...or the lugs themselves.

To demonstrate, do this simple test:

Stand in front of a door that opens toward you. A closet door will do. Have a 12 year-old (or so) child that weighs about a hundred pounds stand on the other side...place his/her hands on the door just above and just below the knob and push hard, putting the legs into it too. Try to turn the knob.

Saying that the link "unlocks" the barrel is technically incorrect...although it's widely used to describe the function. The breech locks under 20,000 pounds psi, and unlocks when the pressure is off the lugs. The link can then disengage the barrel vertically from the slide. If the link tried to do that when the pressure was still on, it would quickly stretch or break, and the front corners of the the barrel and slide lugs would round off in a short time.

Think about it...If you could move fast enough, do you think that you could lift the bolt on a Mauser at the instant of peak pressure? And...if you could...
what would happen?

So many little things to consider... ;)