Rifle: A machine rated in horsepower

M

Montana Pete

Guest
Are there any engineers, science/math teachers, or others out there who love math?

Challenge: Can you take a specific cartridge in a specific rifle and determine the horsepower generated by the rifle?

Bear in mind that a rifle is a machine that produces useful work. Work is measured in foot/pounds. That's a simple calculation and can be found in most reloading manuals.

Now . . . horsepower is a measure of work plotted vs. time. In other words, the power of this machine that is the rifle. A machine rated at 10 horsepower can perform more useful work in a given unit of time than a machine rated at 5 horsepower.

Now, take any rifle and any load you want, and see if you can determine the horsepower produced by said rifle.

I would try this, but I'm an English major, unfortunately, and incapable of the analysis.

I've often wondered about this . . . hope someone takes me up on it.

Montana Pete
 
Horsepower is weight over time. You'd have to define the time. You can calculate the energy generated because that's a finite amount. Horsepower is something that is assumed to be continous.

You could calculate how many horsepower is generated during the acceleration phase of the bullets path down the barrel, but would have to have an accruate time of acceleration to do so. Of course the "horsepower" ends when the powder is burnt.

Energy is easiser. Measure how fast the bullets going, how much it weighs and whalla.
 
4Mesh--

I have thought about this. You can only consider the "machine" (rifle) to be operating when it is actually accelerating the bullet down the barrel.

You need to come up with an estimate of the duration the "machine" operates. That is, what is the time element between ignition of the primer and departure of the bullet from the muzzle? If we do not have an actual acceleration curve, we would need to average the rest speed at ignition against the muzzle velocity-- which contains a time factor.

Once you get the duration that the machine operates -- accelerates one round from rest to the muzzle -- then you have the information needed to assess the horsepower.

I'm the English major, you are the engineer or math teacher -- whatever.

You should be able to do this. Just be prepared for a large number.

I read in the Speer Reloading Manual a situation involving the .223, I believe-- not sure -- where a 1/7 twist barrel would put the spin on a 3500 fps bullet of -- get this -- 330,000 rpm. In this instance, most varmint bullets would literally blow up out of the muzzle due to incredible angular rotation.

The numbers are huge, but that's no reason not to do the numbers.

Hope you can give it a try--
 
Pete

Then there are Rifles that sacrifice ALL other aspects of Rifle performance for one thing. The ability of that Rifle to stack one bullet on top of another in a Competitive Arena......jackie
 
Stolen from elsewhere

Power is the measurement of how much work can be done per unit of time. It can be expressed in either watts or horsepower, depending on whether metric (International System) or English (Imperial) units of measure are used to calculate it. Horsepower is a term first coined by James Watt, who calculated that a single horse can do 33,000 foot-pounds of work in 1 minute.


Step 1
Calculate how much work is done by the device. Work is the measure of force times distance. For instance, raising an object weighing 1 Newton 1 meter results in 1 Newton-meter (or 1 Joule) of work. In English units, raising an object weighing 1 pound 1 foot results in 1 foot-pound of work.

Step 2
Understand the definition of "weight." Weight is a measurement of mass multiplied the acceleration of gravity. In SI units, kilogram is a measurement of mass, although it is commonly used to refer to weight. 1 kilogram of mass multiplied by the acceleration of gravity is 1 Newton of weight. Similarly, in English units, a pound is a measurement of weight, and slugs is a measurement of mass, making a pound equal to 1 slug multiplied by the acceleration of gravity.

Step 3
Learn how to define "work." To do work, you must move an object in the same direction as the force that was applied to it. For instance, if you try to lift a box, but can't, you haven't done any work even though the attempt my tire you. If you lift the box and carry it across the room, only the distance that you lifted the box counts as work.

Step 4
Determine how much time was required to do the work. If it took 1 second to raise the 1-Newton weight 1 meter, the power of the device that raised the weight is 1 Joule per second or 1 watt. In English units, the device that raised a 1-pound weight 1 foot in 1 second is 1 foot-pound per second.

Step 5
Convert foot-pounds per second into horsepower by dividing by 550. You can also convert watts to horsepower if you know that 746 watts equals 1 horsepower.
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There you go. I have to load ammo and all I'm concerned with is how well they group and score. HP don't win, and this ain't a race!
 
It seems to me if the horsepower were determinable as associated with a rifle/cartridge combination, that there would be two horsepowers that you would be looking at. The first would be the indicated or calculated amount within the barrel (I guess you could say as related to internal ballistics), and would have to include in the equation all of the losses associated with that process. The other horsepower would have to do with the bullet at the moment it exits the muzzle. In my way of thinking (i know, that could be very bad:confused:), the bullet would have to be immediately arrested, and it's energy available put into a device for measuring brake horsepower. Perhaps we might call this external horsepower. It too would have losses that would have to be taken into consideration.

So, we would be talking about the produced h.p., or the delivered h.p.

The internal portion would seem to come from an elaborate laboratory test and associated with calculation.
The external portion might be pulled off if there were a device suitable for that determination.

Perhaps a rocket scientist could calculate the whole thing in a few moments.

My $.02
 
Montana Pete said:
Are there any engineers, science/math teachers, or others out there who love math?

Challenge: Can you take a specific cartridge in a specific rifle and determine the horsepower generated by the rifle?

Bear in mind that a rifle is a machine that produces useful work.
Montana Pete
Click to expand...


Mr. Montana Pete would you believe, that it can be calculated.

Mr. Montana Pete in your own words please explain to us, why do you feel to know how many horsepower a particular cartridge will have?

Mr. Montana Pete would you believe, that to any non-scientist shooter who can't already flawlesly calculate the horsepower, this information is totally useless.

Con
 
550 foot pounds per second is 1 horsepower.
How it can be related to a bullet I have no idea and I don't think the math exists as it has never been required as far as I know .
Very loosely if you have 1100 foot pounds of muzzel energy you could loosely describe the the gun as 2 HP at the muzzel and a half dead Donkey at 1000 yards .:D
 
I could be waaay off but taking a quick stab at it I came up with this based on a 300 win mag load.

3633 ft/lbs energy at muzzle = .001835 hp/hour
Time from ignition to bullet exit from muzzle according to quick load .0012 seconds

Number of .0012 time slices per hour = 3,000,000

.001835 hp/hr x 3,000,000 = 5505 hp

As I said above I could be way off but maybe it will get someone smarter thinking.

Stephen Hall
 
SBH said:
I could be waaay off but taking a quick stab at it I came up with this based on a 300 win mag load.

3633 ft/lbs energy at muzzle = .001835 hp/hour
Time from ignition to bullet exit from muzzle according to quick load .0012 seconds

Number of .0012 time slices per hour = 3,000,000

.001835 hp/hr x 3,000,000 = 5505 hp

As I said above I could be way off but maybe it will get someone smarter thinking.

Stephen Hall
Click to expand...


Yup Steve, that's WAYYY!!! off :)

There's really nothing to "think about" here....... this idea that the discharge of a rifle is super-duper powerful or "mega-horsepower" is what's way off.

The act of firing a rifle is no more "powerful" nor mystical than the controlled deflagration or "explosion" that goes on inside of an internal combustion motor. The difference is that the rifle only does it ONCE.......perty wimpy really......EVERY DAY when you drive your car you fire hundreds of thousands of "rifle shot equivalents".


BUT..... with a huge difference. ONE firing stroke of your 350Chev has more energy that a shot from a rifle, and it fires OVER and OVER and OVER.....

Now a Gatling gun or another sort of machine gun makes "horsepower" over time BUT, to any of you service guys who've actually held the power....... just how much "power" does that little thing have if you were trying to power your APC or HumVee with it? Think about it.....


Now, if one were to actually take the firing cycle of a submachine gun over time......say 3000rds firedX cyclic rate..... one could then quite easily express this in "horsepower". Meaningless but easy.


The problem here is in the terminology,the definition of horsepower VS the thing that a rifle does. It doesn't take a "rocket scientist" nor an Engineer nor even any sort of a math whiz to figure this out, just a basic understanding of "work" and "horsepower".......... given a proper definition the "horsepower" can easily be computed.expressed with any unite from watts to ergs to joules to BTU's if you'd like....

al
 
if i were trying to decide the best method, i would chose SBH'S method first, because he mentioned 300 win mag, and we all know that that is the finest cartridge in north america, and alot of the world.

second best method would go to 4MESH, because he obviously has an honest handle on it. he would have been first, but he didn't mention 300 win mag.

third best method would go to jackie schmidt, because he mentioned accuracy, which is what we are all after.

next best method would go to alinwa, because, well, as my father used to say, "that's so far out, it's almost back in again!"
 
longshooter said:
if i were trying to decide the best method, i would chose SBH'S method first, because he mentioned 300 win mag, and we all know that that is the finest cartridge in north america, and alot of the world.
Click to expand...


Gentleman, what do you think?

Con
 
During my freshman year in collage I took Physics 1 and 2 and got very interested in Newton's laws of motion. I actually built a ballistic pendulum to test the velocities of various rifles.

The ballistic pendulum was a 3" pipe filled with sand and paper and capped with a piece of inter-tube rubber. I suspended this thing from thin wire and when I shot into the pendulum it moved forward and upward. The total upward movement would tell you by calculation how fast the pendulum was moving. The pendulum weighed 14 pounds or (14 x 7000) grains. Going to Newton's laws you can determine the weight of the bullet times its velocity= the weight of the pendulum times its velocity.

To make a long story brief, I tested a .222 and several other rifles including a full blown 300 H & H Ackley improved. The 300 Ackley improved with a 150 grain bullet at about 3500 feet per second lifted the pendulum less than 1 foot.

I am not getting into the math again, but that is not much horse power.

Concho Bill
 
On the 300 Win Mag, I'll give another try.

210 grain Bullet. = .03 Lbs.
Launched at 3000 FPS

Muzzle pointed vertically and plumb. Firing straight up.

.03x3000=90 Ft Lbs per second of energy created. (though the energy is created in far less time than 1 second.)

Time already factored by the muzzle velocity. Power is only created for the hypothetical 1 or 2 ms.

90/550 = 0.1636HP

Now, lets say the estimate of ~1ms bullet in barrel is accurate for our discussion. You could then say the gun produces 163.6HP for one thousanth of a second, or you could say it produces 81.8HP for 2 thousanths of a second (milliseconds, ms).

Now, I can hang on to a gun that's 163.6 HP for no time, but would not want to hang onto the shaft of a 1HP motor when someone turns it on if that motor is to be on for any amount of time. The HP is pretty slight if you spread it out over 1 second.

So, if you were to fire continously you could make about enough horsepower to actually do something, but, to get to the numbers we are discussing here, the gun would have to fire at a cyclic rate of 60,000 rounds per minute to even produce 163hp. Unlikely?

Now, take a top fuel dragster that truly does have 5000hp (and then a bunch), can light the candles at the line, blow up or break instantly, and still cover the traps at pretty significant speed. Now THAT'S horsepower.

If the gun made thousands of HP, it would propel us pretty violently back into the cleaning area when shooting.

If someone sees an error in my math, please advise. Keep in mind, we are only talking about the production of HP during the acceleration phase, not some hypothetical HP of millions of shots being fired in succession for a greater timespan.
 
I should stay out, because I'm that English major again without the math or engineering savvy.

Who am I to comment? So don't take me too seriously.

However, I am for Steve. The time the "machine" is operating is very brief. Steve comes up with .0012 seconds. This seems about right.

During that time the rifle does measurable work, in feet/seconds. It is NOT necessary that the "machine" be operating continually over a period of time. Horsepower is force plotted against time. Probably Steve's estimate of 5500 hp. for the rifle is about right.

---------

I think about the example I gave earlier in the thread. Taking a .223 with a 1/7 twist. A bullet exiting the muzzle at 3300 fps will be spinning at 330,000 rpm and is likely to blow up within ten feet of the muzzle. (From the new Speer Manual #14.)

Big numbers and strange physics are actually rather common with high-power rifles.

I wish we could get one of the ballistics engineers from Speer or Sierra to comment here. They would have this totally nailed down, and they would be SURE what they were saying.

A good high-school physics teacher could probably handle this one also.

Not meaning to put down anyone. I honestly do not know for sure what the answers are.
 
Horrsepower is a rate of energy release, not unlike Watts in the metric system.
1 horsepower = 745.67 Watts
foot pounds (ft*lbf) is a unit of energy, not unlike Joules in the metric system
1 foot pound(f) = 0.73756 Joules
1 horsepower = 550 ft*lbf/sec (foot pounds force per second.
1 watt = 1 joule/second

note, lbf is a force not a weight.

So in J Valentines example if you fired a 300 Win Mag with 1100 ft*lbf muzzle energy repeatedly once per second the average energy rate would be two horsepower.

You could also describe the rate of enegy release for an individual shot such as the rate the rifle pumps kinetic energy into the bullet as its traveling down the bore. if that 1100 ft*lbf was put into the bullet in two milliseconds of bore time the horsepower would be 1100 ft*lbf / .002 sec / 550 sec/ft*lbf = 1000 horsepower for 2 milliseconds.

You could also apply horsepower to describe the rate of energy release when an inch long bullet from that 300 WIn Mag strikes and imbeds in a heavy thick armor plate at close range. (1100 ft*lbf energy * (3000 fps * 12 in/ft) / 550 sec/ft*lb = 72,000 horsepower for 27 microseconds.
 
Louis,

I'm not sure which of us is incorrect, but one of us is.

Our numbers are off by approximately one decimal place.

Mine is, 210gn = .03 pounds. 100 of these weigh 3 Lbs.

Launched at 3000 Feet Per Second, = .03 x 3000 or 90 ft Lbs / Sec.

Why is our energy number in such disparity? Am I doing something wrong with that calculation?

EDIT -------------

Possibly answering my own question. Mine is Ft Lbs/Sec where you are talking about Ft Lbs.

I see Sierra Infinity puts my bullet at 4195Ft Lbs, and if you divide by 90, you get 46.6 accelerations per second if a continous stream of bullets is sent. That's saying a millisecond and a quarter per bullet, roughly what we've accepted. Perhaps this is part of it. If so, I like my 163hp example better.
 
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Rifle horsepower.

I'm 63 and my 300 win mag (a Rem 700 Sendero) has been fired under 100 shots. That says it's delivered about one ten-millionth of a horsepower on average during the life of this owner. I doubt i'll ever put a total of 200 though it.

The only thing in question about appling the concept of horsepower to a rifle is what time period should be used. For a machine gun using the cyclic rate would be appropriate.
 
Sustained Fire

The 30mm cannon on a A-10 Thunderbolt with sustained fire would overcome the combined thrust of Both it's turbo-fan engines and push the plane backwards. That's at approx 4000 rounds per min. useing depleted uranium rounds.Check the Mil. specs for Vel. and proj.-powder weights.
 
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