Slow Motion and Frame Capture Cannon fire with some analysis

[seacoastartillery]

   This is the place to post your Frame Capture and Slow Motion videos or comment on such.

This is a posting extracted from the 64-Pounder thread:

Max Caliber wrote:  "It would be great if you could slow that down to super slow motion."

      1,200 FPS (frames per second) is as fast as our company's camera will do, Max.  I have compared this mod. clip with an unaltered one and the speed is the same.  The lanyard whip is just as DD says and has nothing to do with wind.  
 
     Mike and I looked at that clip quite a few times and we guess that mass of concrete is traveling at 150 feet per second.  Parrott-Cannon will tell us if we are close or not.


From Parrott Cannon we now have the answer:

"Based on the video posted the velocity is 180 fps plus or minus 2.8 fps.  I have attached a word document that documents the analysis."  

Thank you Parrott-Cannon.  Now we can calculate muzzle energy per the std. formula.

ME=mxv(sq)divided by 450400.    The mass has to be in grains avoirdupois (7,000 per lb.) and the velocity in feet per second.  The 450400 is the modern constant which works well with most bullet shapes and ballistic coefficients.

ME=959000 x 32400 / 450400

ME=3.10716(10th power)/450400

ME=68,986.678 Foot Pounds


     Also we have this from Max Caliber:  

"I think the blast is especially impressive on that video and frames picked through the whole event would be very interesting."

    I did this for George Gaskill's excellent 30mm rifle shot at the Montana event and there was but one or two comments. Not much interest in an excellent series!  If I have time in the late evening someday, I might try another frame capture series.  But other than, "Oh, fire is peekin" or "Bright flash!" or "Projo's peekin!", what can you say about such a series?  Is there anything intelligent that you can say??

Double D,   Is it possible for you to post that Mod. of our clip that you made?  That might be a good starting point for any discussion.

Thanks,

T&M




    

[Parrott-Cannon]

I just noticed your PM about the shroud dia. being 25 inches instead of 35 inches.  This changes the velocity estimate from 180 fps to 129 fps or a kenetic energy of 35429 ft-ib.

[1Southpaw]

That is impressive , I thought it was the high light  of the Cut Bank Shoot , other than my dissapearing bowling ball   

[seacoastartillery]

    Thanks Double D., for transferring that modified clip.

I just noticed your PM about the shroud dia. being 25 inches instead of 35 inches.  This changes the velocity estimate from 180 fps to 129 fps or a kenetic energy of 35429 ft-ib.

    O.K. John, you are going to have to tell us in layman's terms, how the BLEEP is the O.D. of the tube going to have anything to do with the velocity of the projectile??  Come on Mr. Ballistician, do you realize how quickly that huge, heavy jug of concrete becomes just a black spec against that pale blue Montana sky?  I mean really, you're talking about only a trifle more than One-Third the Velocity of an arrow from an English Long Bow!  

T&M

[GGaskill]

... how the BLEEP is the O.D. of the tube going to have anything to do with the velocity of the projectile?p

He's using that distance as a yardstick to determine how far the shot flies in X number of frames.  There is no other scale in the image.  So if his "yard" is now 25" long instead of 35", the distance traveled is less.

[seacoastartillery]

     George, I have some days, like today, when I completely disprove Winston Churchill's assertion about the life-long political progression that most people go through.  Here I am a conservative over the age of 40 and I still have no brain!  That's why we keep you around here, George, to spot things like that!!   Thanks.      Tracy


     Ernie,  your quickly disappearing bowling ball probably went into the next section.  That's a shot Mike and I hope to repeat this winter out on the Colorado plains after we get some snow.  We need something for fire prevention.  The smoke-trailing BB will hopefully be filmed from 1 mile down range and 1/2 mile to the North of our East-West range.  A simple composition of KNO3 and sugar will provide the smoke for 30 to 40 seconds which should be good for a two mile shot.  We calculate that 2.5 pounds of Fg should get us there or pretty close.  A movie in 300 FPS speed should get us all the details without restricting the view or reducing the light too much.  Can't do this until we have mailed all those Krupp Howitzers in late January.  Then we will take a week off and 'BOOST' !! a bowling ball.  What was the weight on yours that disappeared, Ernie?

Tracy and Mike

T&M

[gulfcoastblackpowder]

Just for clarification, the constant of 450400 does have units (as do all the other numbers), and the formula is acrually slightly inaccurate (which is why it took me an extra second to see where the constant was derived from):

The base formula for kinetic energy:
KE=1/2*m*v^2

Your constant requires that you use grains, but you don't really need to if you use the base formula:

KE = 1/2 * 137lb(mass) * (180ft/s)^2
KE = 1/2 * 137lb(mass) * 32400ft^2/s^2


As you can see, this will leave us with units of lb(mass)*ft^2/s^2, which is a unit of force, but not as we like to understand it.  To convert it to force, you apply the gravitational constant of 32.2ft/s^2:

F=m*a => 1lb(force) = 1lb(mass) * 32.2ft/s^2, which resulsts in the following:

KE = 1/2 * 137lb(mass) * 32400ft^2/s^2 * (1lb(force)/(1lb(mass) * 32.2ft/s^2))

This can be rewritten as:

KE = 1/2 * 137lb(mass) * 32400ft^2/s^2 * ((1lb(force)*s^2)/(1lb(mass)*32.2ft))

You'll see the units cancel, leaving only lb(force)*ft, which can be rewritten as ft-lb.

What happened to the constant?

KE = 137lb(mass) * 32400ft^2/s^2 * [1/2 * ((1lb(force)*s^2)/(1lb(mass)*32.2ft))]

KE = 137lb(mass) * 32400ft^2/s^2 * ((1lb(force)*s^2)/(1lb(mass)*64.4ft))

In this case, our constant is 1/64.4 + units of (lbf*s^2)/(lbm*ft).

Why does this work without converting to grains?  Because the constant of 450400 is the same thing, but in grain form:

Constant = ((1lb(force)*s^2)/(1lb(mass)*64.4ft)) * 1lb(mass)/7000gr = (1lbf*s^2)/(450400gr*ft)

Because the constant already had the lb mass conversion to grains, you needed your mass in grains.

Here's the same formula with the new velocity (129ft/s) as proof:

KE = 137lb(mass) * 16641ft^2/s^2 * (1lb(force)*s^2)/(1lb(mass)*64.4ft) = 2279817/64.4ft-lb = 35,400ft-lb.

Slight difference in results because I used 32.2 for the gravitational constant rather than 32.1739ft/s^2 or 32.163ft/s^2, which is often used for muzzle velocity calculations.

[Parrott-Cannon]

I just noticed your PM about the shroud dia. being 25 inches instead of 35 inches.  This changes the velocity estimate from 180 fps to 129 fps or a kenetic energy of 35429 ft-ib.

    O.K. John, you are going to have to tell us in layman's terms, how the BLEEP is the O.D. of the tube going to have anything to do with the velocity of the projectile??  Come on Mr. Ballistician, do you realize how quickly that huge, heavy jug of concrete becomes just a black spec against that pale blue Montana sky?  I mean really, you're talking about only a trifle more than One-Third the Velocity of an arrow from an English Long Bow!  

T&M

GGasStill is correct.


I measure the number of pixels across the mortar shroud and calculate a conversion factor feet/pixel.  As the frames in the movie advance the projectile moves X pixels.  The conversion factor is then used to convert this pixel movement in to feet.  Each frame is 0.00083 seconds.  The slope of a linear regression analysis of the distance vs time is the velocity.

I routinely use this method to mortar velocities.  I have demonstrate the validity of this technique by measuring the acceration due to gravity and statictical comparasion with a shooting chrony (errors are less than 2%).  The only difference, in my setup, I have a "Tape" of known length just below the trajectory path.

If you would provide me with the diameter and length of the projectile I can make another set of calculation.

I just realized that the orginal quicktime movie was converted to wmv format this many have changed the pixel ratio.  If you still have the orginal movie please provided a copy.
 

[seacoastartillery]

     The series below reveals quite a bit about the flow of gasses produced by the rapid burning of the Fg powder.  Even the vent plume was interesting.  We will not try to explain everything, because YOU probably have ideas and suppositions just as good as ours.  The 1 Lb. of powder filled only 40% of the chamber which is 4" dia. X 8" long with a hemi end at the bottom.  There was a Dickens designed quick match in the vent, initiated by a friction primer.  Why was it so slow?  There is one pic per every 5 frames in the vent sub-series, one pic per each 2 frames in the entire flame emergence sub-series and one pic per each 3 frames after the projo shows up.  How much horse-power did we lose to blow-by gasses?  The actual shell dia. is 10.660", so you can see that we have plenty of windage between the projectile and the bore dia. of 11.002".  We did this on purpose to reduce the pressure, even at the expense of efficiency.  Can you tell when the back end of the shell clears the muzzle?

Tracy and Mike


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[Double D]

If you want to see the a cool effect if you have a roller wheel on your mouse roll the those picture by.

May suggest I suggest you contact our sponsors found in the GBO BPM&C Sponsors sticky found at the top of our forum and have them build you 10.723 diameter mould to cast zinc projectiles. This is a non paid recording.

[Parrott-Cannon]

I recalculated the velocity base on the wmv video and using the dia. of the projectile.  The cal. velocity is 131 fps.  I also examined the wmv vedio using Camtessa Studio.  There was some distortion and frame rate changes created in the conversion from quicktime to wmv.  These distorations and frame rate changes were caused with what ever program was used for the conversion.  For normal viewing these distorations are of no importance but for video analysis they my cause errors.  I was not able to correct  the distorations or frame rate changes.  A valid video analysis can only be conducted on the orginal quicktime movie or on a conversion done with quicktime pro (26 dollars) or an expensive conversion editing program such as Camtessa Studio (over 800 dollars).

[BoomLover]

T & M, it looks like the back end cleared the muzzle in frame 18, just before frame 19, given the frames vs pic arrangement...2/3's thru frame 18...? + or - 1/3 frame....BoomLover

[Parrott-Cannon]

Terry & Mike

Do you have any range data for this mortar.

[Max Caliber]

Great stuff! Looks to me like frame 16 is where the shot has cleared the barrel since the blast appears to be forced to the side by the base of the shot. Frame 17 shows the blast being directed again to the front.

After further review. The base of the shot could be even with the face of the muzzle somewhere in frames 11 and 12.

[Zulu]

Look at the difference in flame between frames 14 and 15.  I think the shell cleared the muzzle then.
Zulu

[Parrott-Cannon]

Using frame 26 as a reference the projectile cleared the mortar between frames 18 and 19.  The math says frame 18.7.  Assuming each picture is a consective frame in the video.  It also appears there is an off axis shift down from the initial trajectory.  The projectile is falling toward mother earth before it leaves the barrel.  Terry & Mike I think indicated the projectile was undersized would this have caused to tilt as it left the barrel?

[gulfcoastblackpowder]

I think the difference in the flame seen in 15-18 is due to the presence of the projectile in the muzzle.  Once the projectile is obstructing the muzzle, the gasses are forced outward rather than forward, but this doesn't mean the projectile has cleared the muzzle, but rather that it is still there.  For that reason, I think the projectile reached the muzzle between 14 and 15, and escaped the barrel between 18 and 19.  Looking at the progression backwards (like Parrott-Cannon did), I agree with his findings as well, that timing wise, it appears to clear the barrel mid 18.

[seacoastartillery]

If you want to see the a cool effect if you have a roller wheel on your mouse roll the those picture by.

May suggest I suggest you contact our sponsors found in the GBO BPM&C Sponsors sticky found at the top of our forum and have them build you 10.723 diameter mould to cast zinc projectiles. This is a non paid recording.

     Roller wheel slide show!  Reminds me of the stick figure movies I used to make in the back of my Math class in Jr. High School on the back 20 pages of my spiral bound notebook!  I had the teacher doing jumping jacks on one of them as I recall.  Ended up going to summer school to complete Algebra!!

     Double D.,  We will have to consider your idea of finding a mold maker very carefully.  THAT size mold would be BIG BUCKS!!  The solid shot of 11.0" dia. would weigh close to 170 pounds in zinc.  We have a steel shot once used in the petroleum refinery near Denver that weighs 177 pounds. It's just a little over 11" maybe by .050" or so.  How much does 170 Lbs. of zinc cost?

     Our guess for the frame which displays the emergence of the projectile is the first frame to display a different flame shape, No. 15.  There is no 'Right Answer' on this question, however, because our ability to see beyond the flame front is exactly what yours is, and that is:  Zilch!  Nothing!  So who really knows?

     I just sent a whole new set of data from my range notebook to John who has developed the internal and external ballistics programs.  And yes, some of my assumptions from memory were wrong.  I also sent him a copy of my original movie, the 10 Meg. one without those convenient alterations DD accomplished for those of us too impatient to wait 6 or7 minutes for some action to occur, (Mike and I include ourselves in this group)!!  Now he will have much more accurate results for us, but we must be patient, or try to be.

     Also, from frame 8 up to frame 11 you can see jets of incandescent gas (flames) coming from different points around the projectile.  Is this because the projo is moving or tilting as it starts to move out of the bore, blocking egress of the hot gasses here and there as it moves?  We really don't know.  Maybe you have a better explanation for this phenomena?

     In addition, do you see those two specs that appear in frame 19 just ahead of the projectile emergence from the smoke cloud?  They stay ahead of the projectile and diverge slightly, increasing the distance between them out to frame 27, when the leading one disappears.  What the heck are they??  We loaded no gravel in with that shot.  No chips off the concrete were observed on any shot, either.  What are those speeding specs?

We appreciate your participation;  we ARE NOT experts in this area of ballistics and projectile flight phenomena.  Not at all!

Mike and Tracy

[dan610324]

if you look at the last picture
take a caliper and messure the length of the projectile on your monitor
and then messure the length from the front of the projectile to the mortars muzzle face on your monitor
check the distance it travels between every picture from the last one until it disappears in smoke and flames
then you will find out that the back of the projectile most probably clear the bore in picture 15

the time between the first evidence of ignition in picture #2 till the projectile have cleared the bore in #15 is just over 1/100 of a second
is it anyone who ever have been asking himself how fast bp really burns ??
how is it possible for the pressure to be able to reduce itself until its out in the low pressure part of the barrel ??
we talk about 1/1000 of a second or so here from nothing to full pressure and another to hold full pressure and another to start lowering pressure
it would be extremely interesting to get the real pressure from a shot at the bottom , middle and front(top) of the chamber and on maybe 4-5 places in that short bore

[Double D]

     Double D.,  We will have to consider your idea of finding a mold maker very carefully.  THAT size mold would be BIG BUCKS!!  The solid shot of 11.0" dia. would weigh close to 170 pounds in zinc.  We have a steel shot once used in the petroleum refinery near Denver that weighs 177 pounds. It's just a little over 11" maybe by .050" or so.  How much does 170 Lbs. of zinc cost?
 

Mike and Tracy

$200 or $300 for a mould and $2400 for zinc for 10 round balls and your $25,000 mortar is now worth $30,000...and by time you are old enough to retire who knows how much its worth...

[GGaskill]

It would most likely be a candidate for a sand mould in a size like this.  Then the windage would actually be used for its real purpose--allowing for variation in shot diameter.  And it really should be hollow for the bursting charge.   

Zinc was about a dollar a pound the last time I bought any.

[Double D]

I pulled th price from the Rortmetal website at $1.39, but a buck would be even better; only $1700 for ten rounds...

[GGaskill]

An 11" shell should weigh approximately 122 pounds.  A solid aluminum 11" shot would weigh about 68 pounds.  Unless you were trying for a distance record, I would think aluminum would be the way to go since you would use about half the material.

[Victor3]

 I wonder what percentage of energy is lost due to gas escaping around the projectile before it exits the bore? Looks like it might be substantial, considering that the fireball appears to peter out quite a bit before the jug is seen.

[seacoastartillery]

     From now on I will consult my range notes which are fairly thorough and usually made at each stage of a particular artillery test of range, accuracy, new projectile, different powder charge, etc.  Relying on memory alone is not only inaccurate, but can be the cause of scewed analysis reports, something we will try hard never to do again.  Our corrective action will be to provide data from our range results every time we have a request for such and not from memory.  Parrott-Cannon, Dr. John Gallagher, was kind enough to run these new results through several various programs he has developed and has some interesting results of his analysis to report to the membership.  Permission to publish these new results  were obtained prior to initiating our posting today.

Tracy and Mike

     The data presented in this report was developed on computer programs written by John B. Gallagher.   The following data was provided by SeacoastArtillery:

•   A QuickTime movie of the mortar firing.  The movie was taken with a Casio Exilim EX-F1 at 1200 frames per second.
•   Mortar Data
o   Outside Diameter – 25 inches
o   Bore – 11 inches
o   Grains Fg –  10,500
•   Projectile Data
o   Diameter – 10.66 inches
o   Length – 14.5 inches
o   Weight – 90 pounds
 
Method:
•   TrackIt a computer program developed by Dr. Gallagher was used to measure the distance traveled by the projectile from frame to frame in the movie.  Statistical analysis using JMP software was used to calculate the velocity from the distance versus time data extracted with TrackIt.
•   Drag a computer program developed by Dr. Gallagher was used to calculate the coefficient of drag curve for the projectile.
•   Lock’nLoad a computer program developed by Dr. Gallagher was used to calculate the trajectory of the projectile.  It was also used to calculate a velocity for the projectile described above to achieve a 1200 foot range.

Results:

•   The video analysis gave a velocity of 203.5 feet per second (fps) plus or minus 5 fps.
•   Trajectory (calculated using Lock’nLoad)  :
o   Range - 1215.5
o   Time to target  - 8.8 seconds
o   Angle of Impact - -46.5 degrees
o   Terminal Velocity – 192.3 fps
o   Kinetic energy at impact – 51,762 ft. lbs.
o   Maximum Projectile Height – 312 feet
o   Ballistic coefficient – 0.9293 (calculated using Drag)
•   Velocity based on Range and Ballistic Coefficient – 202.1 fps calculated using Lock’nLoad
 

[Double D]

Range, what unit of measure?

[seacoastartillery]

   I think we will stick to the jugs of concrete fellas.  The cost of that much zinc, even with a hollow shell, would be prohibitive, unless we look at it like DD suggests and develop a whole gun, ammo, trailer and kit package and then haul it around to the MG and cannon shoots until we are to feeble to set it up anymore.

     

An 11" shell should weigh approximately 122 pounds.  A solid aluminum 11" shot would weigh about 68 pounds.  Unless you were trying for a distance record, I would think aluminum would be the way to go since you would use about half the material.

     Our local aluminum cut-off dealer charges about $2.50 per pound for small pieces of any grade, 6061, 7010, etc.  For a billet end of 100 pounds, which could be turned on our lathe, the cost would be about $2.00 per lb.  $200 per shot is still way too steep for us.  Thanks George and everyone for the info, but our cost for materials is only $12.00 per concrete jug, pretty cheap by comparison.  We could make some interesting variations on the standard 19", 137 pound plug or the 13", 88 lb. plug or the 14.5", 90 pound variant with two 10.66" Dia. circular pieces of Baltic Birch plywood forming a base protector plate to prevent concrete chipping during firing.  This last was the type we shot in the movie clip.  You can see the outer ply burning as the projectile ascends. 

I wonder what percentage of energy is lost due to gas escaping around the projectile before it exits the bore? Looks like it might be substantial, considering that the fireball appears to peter out quite a bit before the jug is seen.

     Victor,   Somewhere in all this I did mention that we gave this Paixhans Monster Mortar and concrete filled water jug projectile a very generous windage to keep the pressure low.  11.00"-10.66"=.340" Windage  A standard windage of 1/40th would be .275", or 19% less windage that the big Paixhans has.  Sure it is less efficient, but we want our lumber yard carriage to last, so more gentle ascensions of concrete masses are wanted.  Who really cares how many pounds of powder per mile we burn?  Actually we like watching a slower take off and you actually have time to watch it rise toward 300 or 400 feet as it slips the surly bonds of earth.  Even at a terminal velocity of only 192.3 fps, the big, heavy, jug still has 51,762 ft. lbs of energy to expend at impact.  Can you imagine what that would do to the roof of the family truckster??  How far is Hernando, Florida Cannon shoot from Denver anyhow?

     Dan, you are right, it would be really cool if we could get pressure readings from the chamber and several places in the bore as well.  I bet the reduction is dramatic per the mortar's High/Low Pressure principle.

     Double D.  I mentioned several times in these postings that the range for that shot was 400 yards.  Mike and I both measured our pace at the local High School football field before we left for Montana and recorded an average of 4 trips of 100 yards each.  As long as you know how many average paces you need to travel 100 yards, you can pace off distances quite accurately.  So, what is the unit of range measure, Marine?

Mike and Tracy

[GGaskill]

I don't know if these would survive being launched but they aren't too expensive--http://www.save-on-crafts.com/stoneball.html

[Victor3]

 Neat. They kinda look like the moon. Paint it with glow-in-the-dark stuff and shoot at night. 

[Double D]

The range I refer to is the range in the tabualation---1215.5.  If its feet then that equates to 400 yards