Muzzle brake

[Vibe]

I guess to really burn up some bandwidth we should resurrect the Mother Of All Wind Drift Threads and let vibe have at it eh!

al

You can keep your wind drift threads. Even I won't touch one of those. Some of you folks are just down right fanatical in your mystcism when it comes to wind. (And the rimfire shooters are worse - they have to deal with transonic turbulence).

 

[alinwa]

Al
Damage absorbs energy - not "weak", it's a fact. How many fortunes did Mercedes make when they incorporated "Crumple zones" into their car designs? Ever wonder why that works? Because it disipates energy away from the momentum "reaction" and prevent's it from being transfered to the driver. It takes force and energy to deform a material, deform it beyond it's elastic limit and only a small fraction of that force and energy gets returned as rebound. The beanbag has a very low elastic limit, practically non existant, same as the deadblow hammer much lower than the steel plate target. The steel ball and the steel plate have similar limits, though one may be harder than the other, The softer of the two will sustain the most yeilding due to the very small initial contact area, and a permanent mark will be left indicating where this "failure" occured. The superball will fully deform, but not past it's elastic limit, and will spread the force over a large enough area that it will not damage the steel plate, and then rebound leaving no mark on either target or ball (A rubber ball will act similarly, but will lose more energy to internal hysteresis heating) point being that the superball loses the least amout of energy to by products and keeps closer to the same energy in the opposite direction. Now the force that causes the ball to bounce is also "felt" by the target.

Has your son ever seen one of the "real" old school Super Balls? They did act lot like Flubber, or as close as one could get without defying the laws of nature. Drop one from 10' up and it would bouce back to 9'-6".
Now where do you suppose it gets the power to lift itself over 9' in the air?
And did it have to shove against the ground once to stop and once again to bounce back?

Nope.

Mostly true this time, except for the purple part Even it is "true" in that the target does "feel" the super ball, but not very much. (And herein lies the problem...)

Speaking of superballs and my son, YES he's seen them. I kept a few of the big black ones. I do stuff like that..... I've got several large boxes of opened and unopened toys from the last 35yrs. Toys which fall into the category of "Good Stuff." I've got multiple copies of all Erno Rubiks' puzzles, at least a dozen gyroscopes from different eras, NiTi metal "motors" and other "perpetual motion" or oddly powered devices, spring powered cars from Germany, Jacobs Ladders in several permutations, optical puzzles, flying toys from ornithopters to air screws to Xylo's..... I collect this stuff. I feel that if you teach a kid to THINK and to enjoy it that it prepares them for anything.

ANYway....... here's the thing you're missing.

YES, the target "feels" the superball but not nearly as much as it feels the beanbag. (And BTW THIS is the function of a deadblow hammer, to transfer nearly all of it's energy to the target, NOT to "limit damage.") You ever get hit with a sap? I have.


So, point by point:

- Crumple zones...... designed to crumple when you hit a tree to dissipate and redirect as much energy as possible via the mechanisms of "heat" and spreading the impulse over a longer time. irrelevant unless the tree is the rifle.....

- Bean bag, elastic limits, heat hysteresis blah blah blahhh, all TRUE, but irrelevant. You're forgetting that we're talking about THE STEEL PLATE here, the muzzle brake, we don't WANT the ejecta (superball) to retain energy... we want it to transfer its energy to the rifle.

- And your last point, phrased as a question...."And did it have to shove against the ground once to stop and once again to bounce back?"



What does the Law Of Conservation Of Energy have to say on the subject? (Answer- "The total amount of energy in an isolated system remains constant.......and se")


You see, on the surface your answer "looks" right. You're saying that the superball expends itself fully against the steel plate while still storing ("retaining") a bunch of energy WHICH IT THEN REUSES to launch itself back up for another go...

This defies the laws of physics.


Given an enclosed system:

You build a box on the moon which includes a launching platform on top and a steel plate on the bottom. Under the steel plate you plant a force measuring device.... (This can be done any number of ways but we'll just call it a device) Or, to make it simpler you could build it here on earth and exhaust the chamber. Not simple, but cheaper than going to the moon.

From the launching platform you drop a beanbag massing 1 kilogram .....'Plop!".... and you measure the force applied (transferred) to the plate.

NOW..... (And here's where your train derails) ... you drop the superball.... BOING, BOINg, BOIng, BOing, Boing, boing, oing, oinoin-oin- oi o ........ and you measure the force applied (transferred) to the plate.


Seee?


YOU are telling me that the superduperball just keeps on a'hammering applying and reapplying force such that it's "transferring more energy!"

Or making energy?

STORING energy and RE-releasing it???


???

My kid was RIGHT!

In 15 seconds he was right. He didn't even THINK, he just reacted, RIGHTLY..

"flubber"

Muddy thinking.

(Unless you can show me that the superball somehow makes more energy than was loaded into the system)


al


On another note..... I nearly got expelled my junior yr over one of those superduperballs. You see we had this cool gym with a solid ceiling and walls. No sheetrock, no celotex.....solid.

And I had an 86mph throwing arm AND I was wicked adept with a sling....

And I'm a curious sort.

It took me several weeks to find myself totally alone in the gym WITH a 3oz black superduperball over 2" in diameter and WITH a 4' long sling 'specially built to hurl it and WITH the bleachers folded in.........

I fired that mother off (frickin'wickedAWESOME!!)and the ball was on its second circuit and starting to work horizontal when the girls' coach walked in.








And no one was hurt while conducting this experiment in elemental physics.

I'd do it again.

 

[alinwa]

This reminds me of something.....since anyone interested is already here

This question hasn't been up on the board for several years now:



Juggler Problem (abridged version)

A juggler wants to cross a bridge rated at 200lb.

HE weighs 190 lb and he's carrying 3 bowling pins @ 5lb each, total 205lb.

Can he juggle his way across?


This is actually the same problem as the muzzle brake/steel plate problem but not everyone recognizes it.

al

 

[alinwa]

LOLOL!!

Nope....

even your edit can't salvage your face on this one vibe

al

 

[sbindy]

When you run the calculator you will see that an added grain of powder produces more recoil than an added grain of bullet weight. The law of conservation of momentum tells you why this is -- it's because the velocity of a grain of powder (gases) is greater than the velocity of the bullet. Of course, this can't be true until the bullet leaves the barrel, allowing the propellant gases to accelerate to their maximum velocity.

Toby Bradshaw
baywingdb@comcast.net

I am in total agreement with this and it is easily proven. In my .308, the recoil is mild whether it is loaded with 150gr or a 180 gr bullet. The case only uses 42-45grs of powder. My .300 Win Mag uses 72-75grs of powder and it doesnt matter if your shooting 150 or 180gr bullet, it kicks 3 times as hard as that .308. I wouldn't even want to think about what a .30-378WBY would kick like. Worse than my .375 H&H I bet, and that rifle kicks enough.

The whole point being that 30grs of powder accounts for alot more recoil force than 30grs of bullet weight.

 

[Vibe]

Assume a muzzle brake that captures all 50grains of the gas and redirects is around a semi toroidal path of radius 2" essentially all of the gas will then experience and transfer force due to
Fc = mv2/r Integrated for forward acting components from 0 to Pi (0° to 180°)
Which is going to be larger than the F=M(Aof turbulent dispersion)

The fact that you recognize that the juggler problem is the same should give you the answer here. When the juggler accelerates the pin to launch it back aloft, he is exerting much more than just the "weight" of the single pin, so his weight at that time is 190 +the mass*accel of the pin he is catching + the mass * accel of the pin he is launching. This is going to be much higher than the 205 pounds he might have weighed just keeping them still.

There's no escape from Newtons Third Law. For every action there is an equal and opposite reaction. So if you Stop a mass, the reaction can not be as great as it would be to not only stop it, but to cause it to reverse direction at something close to it's initial velocity. In the bean bag vs the superball, assuming equal mass, the superball has the greater reaction force - per this same Law.

 

[alinwa]

Assume a muzzle brake that captures all 50grains of the gas and redirects is around a semi toroidal path of radius 2" essentially all of the gas will then experience and transfer force due to
Fc = mv2/r Integrated for forward acting components from 0 to Pi (0° to 180°)
Which is going to be larger than the F=M(Aof turbulent dispersion)


Correct, irrelevant but correct. Of course a suppressor is even MORE efficient. The acting agent here is to capture, redirect or otherwise utilize ALL THE GAS..... what you DO with the gas, where you send it. point it or otherwise spindle it is irrelevant.



There's no escape from Newtons Third Law. For every action there is an equal and opposite reaction. So if you Stop a mass, the reaction can not be as great as it would be to not only stop it, but to cause it to reverse direction at something close to it's initial velocity. In the bean bag vs the superball, assuming equal mass, the superball has the greater reaction force - per this same Law.

Huhhh??

And here's where we part ways.... "the superball has a greater reaction force"......

You're still making energy.

We HAVE let's say 30% of the total energy available to use, it's being wasted and we can recapture it....... We can use all or part of it.....

We can't get it to work coming and going!

al

 

[Vibe]

And here's where we part ways.... "the superball has a greater reaction force"......

You're still making energy.

Nope, just utilizing ALL of it.

We can't get it to work coming and going!

al

Newton says we can. Now since the most simplistic use of this says that the muzzle blast is then directed right back at the shooter, we might have cause to not WANT to, but the possibility of doing so still exists. The ideal option would be to again redirect the gas at the rear of the barrel, by using a containment shroud, after the redirected muzzle gas has lost a lot of it's velocity and will not provide another rearward thrust. Alternately we could simply extend the containment shroud back past the shooter like the Croatian RT-20 mentioned earlier.

 

[alinwa]

Nope, just utilizing ALL of it.

But you're NOT. If it escapes the system it's not being transferred.


Newton says we can. Now since the most simplistic use of this says that the muzzle blast is then directed right back at the shooter, we might have cause to not WANT to, but the possibility of doing so still exists. The ideal option would be to again redirect the gas at the rear of the barrel, by using a containment shroud, after the redirected muzzle gas has lost a lot of it's velocity and will not provide another rearward thrust.

There IS NO "another rearward thrust!" The energy of the reaction mass was already used when it impinged upon the redirection plates. Anything escaping to the rear is waste. And why run it 'way back to the "rear of the barrel?" If you just catch it at the muzzle, (suppressor), we're done.


Alternately we could simply extend the containment shroud back past the shooter like the Croatian RT-20 mentioned earlier.

And if we "simply extend the containment shroud...." we're only doing it to protect the shooter, NOT to somehow make it more effective. In a perfect world we'll rob the gas of nearly ALL its inertia and what's left will escape as a gentle hisssss.......

Let's keep this wicked simple vibe..... IF ENERGY ESCAPES THE SYSTEM.... then how can it be anything but waste? I don't care whether it's "heat," mass or synthesized chicken fat, it's LEFT the BUILDING Elvis!! It did NOT expend its energy.......

Unlike a rocket, we're not using live reaction mass. The reaction is OVER, all we're doing is catching the gaseous ejecta which would be wasted.

To hearken back to our vacuum drop-box, both the beanbag and the superball will transfer "one Ft/Kg" of energy to the plate but the beanbag does it more efficiently because it expends 'wayyy less as "heat" which will not register on the plate.

And BTW NEITHER the chicken truck nor the juggler actually translates to the muzzlebrake. In fact, to an Engineer (note Cap) the two problems are DISSIMILAR because both the juggler and the chicken truck will smash their respective carriers to flinders...... Because there's another factor at work. Anyone care to point out the tremendous difference between the two? (When I brought in the juggler I fully expected someone to raise their hand and say "but, but BUT!!! There's another factor at work!! NOT the same puzzle!!)

The chicken truck and the juggler are the same problem.

The muzzle brake and the moon box are the same problem.

But the puzzles with living creatures in them ARE NOT the same as the two puzzles using dead weights.

What's different?

al

 

[alinwa]

The ideal option would be to again redirect the gas at the rear of the barrel, by using a containment shroud, after the redirected muzzle gas has lost a lot of it's velocity and will not provide another rearward thrust.

I had to add this sub-quote separately.

This is actually kinda' funny! Your sub brain is GETTING IT

What your sub brain is saying is that "if you STOP the gas...... NO rearward thrust..." then you've achieved your goal.


Now WHY go through with all the twisting and turning and redirecting histrionics?? "Extend the tube back past the shooter"...... WHY??? "Rearward thrust"....... WHY???

Just CATCH THE WAD OF EJECTA... Bimm..... and you're done!

al

 

[alinwa]

The whole point being that 30grs of powder accounts for alot more recoil force than 30grs of bullet weight.

Steve, this is most certainly true. And the REASON it's true is because energy builds as the SQUARE of velocity whereas it's linear to charge weight.

(I worded this poorly but it's essentially true)

al

 

[alinwa]

OK now vibe...... I need one simple answer re the moon box.

Beanbag VS bouncing ball.

DO YOU BELIEVE that the bouncing ball is "expending more energy" because it's "stopping and starting" every time it hits the plate, "bounding and rebounding?"

Yes or No.

No figures, they muddy the waters.

No ergs, no joules nor watts nor calcs.....

Just YES or NO.

al

 

[tobybradshaw]

Just so Vibe doesn't have to do all the talking (that is, all the talking that contains the correct answers), perhaps this Walter Lewin lecture will be helpful:

http://academicearth.org/lectures/elastic-and-inelastic-collisions

Of course, Walter Lewin, like Galileo, Newton, and Einstein, doesn't "make stuff," so maybe they can't be taken seriously. Luckily, the aforementioned do make one thing that has been scarce in this thread: sense.

It's a good thing that one need not understand how a firearm (or an automobile, or sexual reproduction) functions in order to use it.

Toby Bradshaw
baywingdb@comcast.net

 

[alinwa]

When are you'se guys going to understand that the rifle IS NOT A CLOSED SYSTEM unless you close it? "Turning the gas around" isn't closing the system. The moon box is enclosed. While calc'ing the net energy loss of the beanbag VS the superball in the box would be fun.... the ANSWER is that both will transmit very nearly all of their energy to the plate, BECAUSE you've mfgd a closed system. The superball would take a long time to do it, but IN THE END it would come to rest having transferred some of its energy to the plate and expended the rest as "heat." THE TOTAL ENERGY in the system was generated by accelerating the 1Kg object over 1ft. There is no more no matter how you parse it. The superball will not "exert more reaction force" on the measuring plate just because it spreads out the reaction.

To "close" the muzzle brake system you must capture and use all the gas.

Lewin understands this stuff,he can answer the questions. But nothing in this video was enlightening, just a simple explanation of conservation.

You two just talk it, poorly, you don't get it, you don't feel it.


BTW, neither the juggler nor the chicken truck are closed systems either. Lewin would describe them as "superelastic" because within the system you've got potential being unleashed in the form of muscular energy which is being added into the system being described......this muscular energy fuels the juggling/flying to produce a higher net effect on the bridge/truck.


BTW, this statement sure looks convincing... "So if you Stop a mass, the reaction can not be as great as it would be to not only stop it, but to cause it to reverse direction at something close to it's initial velocity." until you apply it to the moon box problem. What vibe is SAYING is that when the 1Kg superball hits the plate in the moon box and bounces the plate will register say 9/10 of the available energy...... then on the next bounce 8/10..... and then 7/10 and so on until the ball quits bouncing.


'AT's a lotta' tenths right thar!


What you'se guys can't understand is that the superball IS NOT STOPPED just because it momentarily came to rest and reversed direction.



al

 

[Vibe]

Just so Vibe doesn't have to do all the talking (that is, all the talking that contains the correct answers), perhaps this Walter Lewin lecture will be helpful:

http://academicearth.org/lectures/elastic-and-inelastic-collisions

Toby Bradshaw
baywingdb@comcast.net

Thanks Toby. I can use all the help available. I would suppose it's obvious why I did not go into teaching.
It's been a long time since I was in first year Physics that snot nosed kids fresh out high school were expected to understand.

Al. Did you not notice the "Tennis ball homework"?
The Momentum transferred to a wall by a beanbag would be MV
The Momentum transferred to the same wall by an elastic ball was 2MV

Not a lot of confusion there.

The momentum transferred to the rifle by a perfect suppressor that catches all the gas will be MV (Actually mV=(M+m)v)
The Momentum transferred to the rifle by a perfect brake that redirects the gas direction, without appreciably slowing it down, is 2MV - after being turned around the gas is no longer "in the system", as you've noticed.

Our 50 grains of gas will remove 4.76 ft/sec from the recoil velocity of our 9lb rifle using a perfect suppressor, about the same as a side directing brake.

But
The same 50 grains of gas will remove 9.5ft/sec from the same rifle if we simply turn it around and point it to the rear.

I just plugged the numbers we've been using into the equations provided in the lecture.
Can you see the difference?

 

[tobybradshaw]

I would suppose it's obvious why I did not go into teaching.

Actually, you are doing a great teaching job. You just need pupils, like 4Mesh in the horsepower thread, who are really trying to understand the physics.

Toby Bradshaw
baywingdb@comcast.net

 

[alinwa]

Actually, you are doing a great teaching job. You just need pupils, like 4Mesh in the horsepower thread, who are really trying to understand the physics.

Toby Bradshaw
baywingdb@comcast.net

Toby, plugging numbers into someone else's equation is not indicative of understanding the physics.

the only problem with the horsepower thread is that somewhere "a horsepower" got defined as a THING, as in unit of measure (the work required to lift 550lb 1ft in 1 second) instead of a RATE.







Ok, vibe

So you're calling the suppressor an "inelastic collision" and your reversing muzzlebrake an "elastic collision."

But you don't understand the concepts....you plug in numbers having made invalid assumptions. "Doing" the physics without understanding the physics will get you through school but not through a job of building something that works.

In truth a bouncing ball is an inelastic collision as much as the velcro'd cars in the vid. "inelasticity" from the frame of a removed observer refers to converting momentum, to heat, mainly. Watching the car that struck the other car and STUCK with velcro isn't really a good example of an inelastic collision. From the observers frame momentum WAS preserved, just in the original direction. (less a good portion of gunk due only to the velcro interface)

You state, QUOTE...... "The Momentum transferred to the rifle by a perfect brake that redirects the gas direction, without appreciably slowing it down, is 2MV - after being turned around the gas is no longer "in the system", as you've noticed."

"without appreciably slowing it down....."


heLLOOOO!!!!

The rifle is a SLED not a WALL.....


The gas is friggin' COASTING!!! If it doesn't slow down then it HASN'T TRANSFERRED ANYTHING! It's taken it all back with it just like a superball does off a wall. REGISTERING a momentary force is not work (force over distance) because the wall did not move.

"LOSE speed"...... slow down...... TRANSFER energy to the rifle, that IS the func we're looking for hey....movement of the rifle.

LOSE energy, momentum, heat, rate of displacement WHATEVER..... if it doesn't transfer then no work is done. It CANNOT change direction, state, mass, etc without an energy transfer. (loss from the original object/state)

Conversely if you magically get it to change (direction, state, velocity, mass etc) WITHOUT LOSING then you've mfgd energy.

In the vid the little air sleds exhibit conservation nicely but notice, NO FREE ENERGY!! Energy is transferred and conserved. The little sled hits the big sled and LOSES VELOCITY, it doesn't return having "not appreciably slowed down"..........


duhhhh


Your raceway is flawed on many fronts. There are vectors being generated and resisted in all sorts of directions. But we needn't GO there until you've shown me where you're generating the extra energy in your superball analogies....the problem with all your supposed examples is that you've never HARVESTED your momentum. Registering the potential for work by measuring a momentary impulse in a scalar sense does NOT measure work. Catching the impulse and transferring it to another object completely (harvesting it) LEAVES NOTHING.... You can't feel that. You haven't factored it in. Instead you're accusing me of "not understanding" steenking high school physics!


I think that where you're screwing up is in treating the steel plate (or the muzzle brake) as a WALL...... (tennis ball analogy anyone??) which DOES give back. (no harvest, no transfer) But I don't know this, I only know that your contentions are flawed.

But this is completely irrelevant.

BOTTOM LINE...... a perfect suppressor sucks off nearly ALL the available energy, yeahh there's heat loss but no more than in a compressive muzzlebrake situation.......the only downside is that it has to drag the gas mass with it as it's bleeding pressure, but the gas ain't all that heavy compared to the rifle..(oops, the gas doesn't MASS much compared to the rifle...) and once you've robbed it of it's tremendous VELOCITY DERIVED energy load it's easy to carry.

It's TRANSFER guys......call it mv in and mv out all day but until you've USED that mass velocity, transferred it to another object, no work is done on the recipient object. A wall gives it back. YOUR RACEWAY ANALOGY gives it back. But your contention that using your raceway allows you to push twice AND TRANSFER is flawed.


This whole "sending the mass back along its own trajectory undiminished" while ALSO presuming that you've taken (transferred) the energy is just stupidsilly.

freakin' "tennis ball homework" Chuck a dodge ball against the wall and the wall gives it all back. Chuck an equally massive beanbag against the wall and it busts a hole through the sheetrock. YET you contend ........


whatever..


If you want to make the analogy truly valid then use a dodgeball and a lead plate of the same footprint.

Shoot, use a 6" diameter plate of massless yet infinitely rigid unobtanium on the wall to fix the footprint, Exhaust the chamber and hit the plate with a 1kilo bouncy ball and a 1kilo lead slug........avoid all the weird slide forces of the beanbag. Put an equally massless pole on it and hit it with a squishy 1kilo balloon. MV=MV=MV????

Hey.... now make the wall a SLED!!!.....so's you don't have to break it. Note that while the soft squishy balloon effects a nice elastic transfer of momentum it certainly doesn't return at undiminished velocity!




Hey, I just got it. You're ref'ing center of FRAME!!!!! (duhhhh )

And you're RIGHT!!! (Although your turnaround pipe still isn't very good)

vibe is RIGHT!

And Toby is RIGHT........

HALLe-freakin'-LUJAAA!!!!

I get to SAY IT!!!

vibe is right!

vibe is RIGHT!!

VIBE IS RIGHT!!!




Thank you for persisting......


And to all of you reading, following and helping The Vibermeister along here.....


THANK YOU TOO!

My perspective finally readjusted, I RODE THE LIGHTNING instead of standing back and watching it!

LOL

al


of course getting gas to behave in an elastic fashion......

I can at least agree that enormous cupped sails at right angles to the escaping gas SHOULD be as good if not better than a suppressor....

Hey now I'm excited!

 

[tobybradshaw]

I love a story with a happy ending.

Kudos to Vibe, Al, and Isaac.

Toby Bradshaw
baywingdb@comcast.net

 

[Vibe]

And I thought that that was heat lightning in the northwest sky last night. I must have been mistaken, that was the light finally breaking through from up Alinwa way.

But it was a fun discussion. Thanks Al, you did make me work for it, and I found I needed the practice.

But now I'm going to see if I can find the rest of the MIT lectures in that series.

http://academicearth.org/courses/physics-i-classical-mechanics

Toby. Thank you. That site is an absolute treasure trove.

 

[alinwa]

Does this mean Alinwa is going to have to teach this to his son?


Lynn

Already did..... our frames of reference are now more disassociated than ever from this whirling rock. In fact the other son, the one who actually HAS the physics has since checked this thread. I din't teach him NUTTIN' but think that we agree that standing and watching a thing is an inelegant position. 'Course he's more pragmatic than me so "elegant" wouldn't be his choice of phrase.... ..... that said, frame of reference WAS NOT the problem in the Wind Drift Thread! We was all riding the bullet, we just disagree(d) and I STILL contend I'm right on that one........ but we were straying so far from my contention that I felt it best to just drop out, start again another day.

And you must admit I pulled out gracefully.... unlike THIS steenking thread where I was just in the WRONG place at the WRONG time! Standing off and looking at it from the outside.

And yelling.......

Well I guess I was RIGHT from the outside looking in... can't see equal mass velocity coming back........

nawww, there's no saving it.





al