Gun Recoil Replicate with a Solenoid

get the mass of the bullet(hand gun, or any as you will), multiply it with half of the square of its exit velocity, then you got the energy then divide it with the time it takes the bullet to leave the barrel from the point of burst.

(1/2(m_bullet)(V_exit)² /time) --> then you got the ideal wattage.

Since you have 1 joule/t = wattage, time for your solenoid to exert pulse signal to drive a bullet(whatever), t= 1J/wattage multiply it with some factor to compensate actual losses.

i am on it !

Thanks alot :)

(1/2(m_bullet)(V_exit)² /time)

Mbullet = 4 gram

Vexit = 880 M/s

time = barrel length / muzzle velocity ? = 0.37 / 880 = 0.00042

0.5 * 0.004 * 774400 / 0.00042 =~ 3,680,000
3.7 million what ?

What's wrong with that?

That is 1,548.8J at 0.42 millisecond or 3.69MW power.

so, you need a set up, that would generate 1 J at 270 nanoseconds.

3.6 MW from a few grams of black powder (or whatever)? Methinks the sums need revisiting.

Something's really wrong here, as you say.

That's appx the weight of a 22 caliber bullet traveling at about twice the normal muzzle velocity from a rifle.

I'd say they are many orders of magnitude over reality.

Merry Boxing Day.

Power is just the rate of energy, and two ways to manipulate rates as we know it. You either manipulate the denominator, or the numerator. As in this case energy is fixated at 1 joule (numerator), we can only do something on the time rate of exerting that energy.

3.6 MW from a few grams of black powder is not unreasonable.

Taking Lyn's point that 880m/s is a bit fast (I thought bullets went at about Mach 2 ~ 660m/s, but I'm no expert) so assuming charge and bullet mass the same 4 gm (charge volume > bullet volume).

I make bullet energy 1.55kJ = 0.39MJ/kg charge. Hydrocarbon fuels have a calorific value ~ 44MJ/kg. Taking account of the oxygen for combustion it's ~ 10MJ/kg total reactants. Obviously not all of that goes into the bullet, but there's plenty to spare!

It's because the time is short that the power appears high. I don't know, but would guess 0.4ms is not unreasonable for the time taken to explode, or burn if you prefer. Not sure about small arms, but for big guns the propellant, guncotton or something, burns much slower (still milliseconds) than high explosive, or it would blow the gun to bits. That's my understanding anyway.

I have hunted wild pig with .22 caliber ammo with a muzzle velocity of 1,200 m/s, so I don't think 880m/s is unreasonable for a military round.

OK, I was just going by what you said in #6, 880m/s is 2x velocity of a rifle bullet. I don't think anybody said it's a military round (if it affects anything).

Wild - I bet the pig was absolutely livid after being hit by that (royalties to the Gerald the gorilla sketch).

My first assumption, based only on the meager bit of information regarding bullet weight was a .22 caliber civilian rifle round.

When OP finally released the second dribble of info, m4a1 was mentioned.

The M4A1 is indeed a military weapon, with a standard muzzle velocity of 880m/s.

The pig hit the ground dead. Even such a light bullet (55 grains) carries a lot of energy at 1,200m/s.

On reflection, I'm inclined to agree - it was my mental estimate of the combustion time (and the energy density of the propellant, for that matter) that was out. I should've used the back of my trusty old envelope.

As a by-the-by, our company is currently working on a target positioning system for use with a petawatt (10¹⁵W) laser. That's rather more than the world total installed electricity generation capacity, by as the pulse duration is about a femtosecond (10^-15s), the lights don't all go dim when it fires. The beam diameter at the focus is about 10μm.

That's some power density! Anything particular you're hoping to do with it, if it's not an official secret?

It's an experimental set-up at Rutherford Appleton Labs (in Oxfordshire). We're just providing the target positioner.

Not sure exactly what they zap with it. As far as I know, anyone (with enough money) can hire time on it to blow crumbs of whatever to smithereens.

Here's the abstract of a paper based on experiments using it (paper's 10 years old - the laser's been souped up a bit since then):

http://iopscience.iop.org/article/10.1088/0741-3335/47/12B/S65/meta;jsessionid=338E64FC14032F666F11D385E002E40F.c3.iopscience.cld.iop.org

Interesting. I'd heard of an approach to initiate fusion by aiming a number of laser beams at a pellet of hydrogen isotopes in the form of lithium hydrides, and there's a mention of something similar.

I'm curious why your trying replicate "a" gun recoil? Your dealing with varieties of variables, like 1) type of gun 2) the calibar/guage of the said gun, 3) the lenght of the barrel, 3) weight and balance of the said gun, ect. If the said gun is a shot gun, does it have a full choke, modified choke, or no choke?

Is ISIS looking to arm childern with guns they can handle? I know it wouldn't be good for them if their mini- soldier went in-op after their first shot.

The problem, as I see it here, is the two way operation of the solenoid...A spring loaded solenoid will balance out the acceleration of the mass of the plunger and the full stop at extension...a recoil from a rifle is one direction only....air actuated or hydraulic with a measured slow release after impact would work....they do make simulators for real weapons....

Here's a supplier/dealer

http://eli.ee/products/1/recoil-simulation-equipment

The problem, as I see it here, is that this is very likely just a homework question.

The only problem the OP is trying to solve is how to get the correct answer to his homework.

Of, course, I'm just a cynical old bastard.

Putting that aside for a moment, you're still going to have the same problem, unless the solenoid is mounted separately from the gun....

This part was worrying me too.....

If one accepts that it will not be exactly the same with the solenoid, then shooting the slug to the rear, will "pull" the gun forwards for a split second, before the end stop is reached and the gun is pushed backwards....

How good that "feels" in reality I haven't a clue.....But a really heavy slug and progressive acceleration might make it a bit better......

Recoil is a consequence of the conservation of momentum. The momentum of the gun + bullet before and after firing is the same. Figure the momentum delivered to the bullet, i.e. the bullet's mass times its muzzle velocity. This will be the same change in momentum delivered to the gun.

I am assuming you wish to accelerate the core of a solenoid to strike the end of the gun barrel to simulate the recoil. The momentum of the solenoid core needs to have the same momentum as the bullet when it strikes the gun, which is its mass times its velocity.

Let p = momentum, m=mass of solenoid core, and v=velocity of solenoid core. Then p=mv. If E is energy, E = .5mv^2. Solve for energy in terms of mass, assuming momentum is constant. Substitute v=p/m into the energy formula:

E=.5m(p/m)^2 = (.5/m)p^2. So energy required is inversely proportional to the solenoid core's mass for a constant momentum.

E = 1 joule (given). Determine p from bullet mass x muzzle velocity. Solve for m, the mass of the solenoid core.

1 joule would be like a .22 cal short....

• In a Glock 22 frame, using the empty weight of 1.43 lb (0.65 kg), the following was obtained:
• 9 mm Luger: Recoil impulse of 0.78 lb_f·s (3.5 N·s); Recoil velocity of 17.55 ft/s (5.3 m/s); Recoil energy of 6.84 ft·lb_f (9.3 J)
• .357 SIG: Recoil impulse of 1.06 lb_f·s (4.7 N·s); Recoil velocity of 23.78 ft/s (7.2 m/s); Recoil energy of 12.56 ft·lb_f (17.0 J)
• .40 S&W: Recoil impulse of 0.88 lb_f·s (3.9 N·s); Recoil velocity of 19.73 ft/s (6.0 m/s); Recoil energy of 8.64 ft·lb_f (11.7 J)
• In a Smith & Wesson .44 Magnum with 7.5-inch barrel, with an empty weight of 3.125 lb (1.417 kg), the following was obtained:
• .44 Remington Magnum: Recoil impulse of 1.91 lb_f·s (8.5 N·s); Recoil velocity of 19.69 ft/s (6.0 m/s); Recoil energy of 18.81 ft·lb_f (25.5 J)
• In a Smith & Wesson 460 7.5-inch barrel, with an empty weight of 3.5 lb (1.6 kg), the following was obtained:
• .460 S&W Magnum: Recoil impulse of 3.14 lb_f·s (14.0 N·s); Recoil velocity of 28.91 ft/s (8.8 m/s); Recoil energy of 45.43 ft·lb_f (61.6 J)
• In a Smith & Wesson 500 4.5-inch barrel, with an empty weight of 3.5 lb (1.6 kg), the following was obtained:
• .500 S&W Magnum: Recoil impulse of 3.76 lb_f·s (16.7 N·s); Recoil velocity of 34.63 ft/s (10.6 m/s); Recoil energy of 65.17 ft·lb_f (88.4 J)

https://en.wikipedia.org/wiki/Recoil

You don't demonstrate exactly what dj95401 is saying, but close.

Gun recoil is specific to the weapon being fired for a specific round. That is to say, bullet weight, powder charge and the specific weapon all come into play here.

AR-15s use a buffer/recoil spring to reduce the felt recoil. So, how do you deal with that?

So, the homework question is not soluble in its present form, unless a non-specific, generic number is the goal.

Then, what's the use?

A solenoid pulls as much as it pushes = 0 external force...

http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law

A 1-joule impact is caused by a weight of 102 grams falling a distance of 1 metre before impact. If the solenoid 6 inches long with a diameter of 1.5 inches were to release the weight as it falls, job done, and such a device fits the specification in the original post, so no critique would be due.

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Wow, Thanks for all the replys !!!!

let me explain my self better :

i am trying to design a pc gun controller that eumlates (somewhat) the recoil of a gun.

the preffered gun model is an m4a1.

the approach i am considering is to utilise a solenoid to act as a hammer.

i thought i can power it through a high power capacitor and and a portable car jumper kit: lipo battery, 100,000 mah @12V

i cant figure out, how newton thirds law would behave: what system will generate a force that pushes on the player.

the design idea was to make a coil around a tube and to put a free metal rod inside as the hammer.

after the cap fires, and the rod hits a plate, a current in the opposite direction would flow, and return the hammer to its original location, where it will be held in place with a magnet, until it fires again

obviously, much less force is needed to reset the hammer....

the recoil is hard to calculate because there is a recoil suppression system

but, from a quick search on wikipedia i got "free recoil" of 4.3 joules,(is this possible ?)

and i am curious how mach BANG i can get SAFELY from such system.

Thanks everybody !

So, the information needed to work out a sensible response is only to be released at reply #16? How quaint.

Exactly.

And for such a worthwhile cause. A video game.

I think my paint is almost dry. Have to run and check.

I dunno... the gaming market is pretty big.

Training sims help preserve life, and is being utilized within armies and security forces all around the world.

maybe u should go watch the paint dry

You would need to buy one of these and tweak the design...

design a more compact power supply...

...the secret would be in the timing of the acceleration of the rod...

http://www.roadtovr.com/striker-vr-virtual-reality-weapon-recoil-hands-on-interview/

OK, here's how Newton's third law behaves. If your solenoid is contained within the controller, then the average force generated is zero. That doesn't mean it's zero all the time.

If you accelerate a mass (the solenoid core) quickly and decelerate it slowly, you get a big force for a short time rearward (recoil) followed by a smaller force forward for a longer time, the average being zero force.

Obviously this cannot exactly duplicate firing a bullet which is accelerated inside the gun but not decelerated generating an impulse force (recoil) only in the rearward direction.

If you can figure out how to generate a force in only one direction without expelling something (a bullet or rocket exhaust), please give NASA a call.

Hey Johny, I could help you with this in upwork =) if you are willing.

Pardon me for jumping into this blog at such a late time B U T to me and I am sure many others, putting the force of the recoil of a gun into a pc gun game controller is about as dumb, idiotic and unsafe things you can do! One of the main purposes of a pc game controller is to take the danger of actually doing something out and replacing it with much safer visual, low physical levels of force and auditory stimulation. Even the recoil of a Daisy air rifle like the one Ralphy had in the "The Christmas Story" is too much for this application. As his father, mother and teacher all said "You'll shoot your eye out". This could be done very easily by some youngsters holding the controller up to the face, eyes, ears, nose, teeth, jaw, Adam's apple, or any other part of the body and activating the recoil simulator. Just think how rich those legal sharks will get! Even better than the John Manville asbestos and Gulf oil spill settlements!

Would you want your child/grandchild to have one of these simulators in their hands? Make things similar to the gun controller for them. Give them a few pounds of ANFO, a primary detonator and a secondary detonator. Why not some det cord? Maybe, if the kid is smart and can figure things out, give a pound of aluminum powder and petroleum jelly to them. Even better yet, give them 500 lbs of ANFO, the appropriate detonators, and an old car. Boy will that stimulate his senses. You won't need a solenoid to recreate that force. Anything less than a half mile will be its own "solenoid". Last time I did that, under professional supervision, the largest piece left was the torque converter!

Yea, go ahead, stimulate people with the simulated recoil of a gun. If they get really interested in this type of thing they may even become the identical or the mirror image of Jason Pierre-Paul. He doesn't like simulated or real fireworks any more! It started out with the small tiny ones, that could be easily simulated, and went up from there.

Yea, go ahead, the Emergency Rooms will love you!

Good Luck, Old Salt

how can this mechanism generate force feedback and doesnt cancel its forces out

Force: F = m x a

Mass: m = F/a

Acceleration: a = F/m

where, m = Mass, a = Acceleration(meters per second squared)

By varying the time of acceleration, you vary the force in time, this produces the illusion of a projectile being fired...one half of the cycle is slower than the second half of the cycle...Now if I was doing this I would go for a CO2 assisted start of the shaft to negate stiction, and then energize the coil, with perhaps a weak spring on the starting side of the chamber and a locking solenoid to hold the shaft in starting position....and then some return mechanism that would be slower than firing speed enough to enable single shot firing, and then for full auto, a CO2 switching valve to assist in both directions....but with realism you get complexity and with that perhaps cost...it's a trade off

https://www.easycalculation.com/physics/classical-physics/force.php

If I understand your question correctly, you have the force to eject the slug of the solenoid, but you need to stop the slug, too, so that it has a finite throw.

The answer is you can't, unless you eject the solenoid's slug out of the barrel and decouple it from the the firearm. The energy used to launch the slug is equal to the energy to arrest it.

What to do? Well, you could play with time. In other words, eject the slug at one velocity, but arrest it slowly over a longer period of time.

This gives you the illusion of the instant kick in the firearm at a small expense of a longer period of time where the slug slows down.

So, the operative word to explore is called impulse.

Ive been following the discussion with some interest and have some suggestions.

With 21 years in the Army, I remember that in 1960's Basic training we had to learn not to hold rifles away from our bodies, but to allow the energy of firing be tightly coupled to the additional mass tight contact with the shoulder provides. With the M-1 this was necessary to keep from getting more bruises the more we shot, which could lead to flinching that would make them worse.

I suggest you try to make your gaming accessory unable to hurt people who don't have that experience, as lasting injury is possible. Instead, provide a small fraction of the effect by holding the simulated weapon's butt-plate latched against springs electrically compressed between "shots" and released when the trigger is pulled.

In a second career, in engineering, I encountered a discipline called Requirements Verification. What do you really need? How much are you prepared to pay for it -- and what consequences are you ready to accept to get it?

Sounds good. My bid is $500 for the job.

Perhaps if you have a weight inside pushed against a spring toward the front of the controller. The trigger releases it and it moves toward the back and hits a stop. You will have a large impulse force when it hits the back that may be a fair simulation of recoil. You will have a smaller forward force over a longer period as the weight is accelerating which may or may not ruin the simulation.

Just keep it quiet rix, i'm trying to make a living for 2016.

So your wanting to replicate a M4A1 rife, you still have at least 2 more variables to put a number to. (1) which barrel are you going to use, 10.5" 14.5" etc.? And (2) which cartridge are you going to simulate?

You have the math formula, now jhony you have to solve the remaining 2 variables before you can solve what type of actuator/solenoid to use.

Good luck with your project

Given the lack of knowledge of firearms and ballistics of the OP, and their lack of technical savvy, I agree with you that this thread is misguided, if not dangerous.

We have contributed too much already to what may be homework or simply just a misguided attempt to make a kids video game.

A little knowledge is a dangerous thing.

He's working for ISIS, kid soldiers are no good if they have a broken shoulder after shooting the first round. His next thread he'll need the recipe for Semtex for his belt simulator design

"A little knowledge is a dangerous thing." Dude, you demonstrate that daily I hear!

Sorry to be so late to jump in on this. I may have missed the concern about cumulative damage to the device (simulated gun). Real guns need to be cleaned and lubricated fairly frequently or they quit working properly.

If the replication of that kind of power were to be realized in some form of a solenoid, it is going to cause the lights to dim every time the trigger is pulled. That is based on the assumption that you are storing the necessary energy and firing only about once every 5 to 10 seconds.

Have you ever seen a well used chisel? Did it keep it's original shape?