Golf balls not too accurate...Help

[30/40]

Took my replica 1897 French 75 muzzle loading cannon out today.  I fired golf balls for projectiles.  Using 200 gr cannon BP, the balls fly fairly straight for around 50 yards and then curve to the right, left, up, down or may continue straight at radom.  Going to 300 gr, they seemed to fly fairly straight for around 75 yards before curving.  I am patching with 1 layer of paper towel (tried patching with newspaper, but the results were more erratic than with paper towels and the newspaper would sometimes tear). Without a patch, the golf ball loads go "bloop" and the balls hit the ground not too far away.

I am thinking that golf balls are simply too light for accurate shooting
with the velocities I am achieving and that my accuracy will improve with
lead balls.  I am not a golfer, but I can't help but wonder if a golf club
puts spin on the ball which the cannon isn't.

I also think that a patch won't be needed with a lead ball...its weight will
help ensure burning of the powder.

On the plus side, golf balls are cheap.

Opinions?

Thanks,
30/40

[CU_Cannon]

The inaccuracy is most likely due to the spin on the ball as it leaves the barrel.  Since golf balls are so light any spin will cause them to curve.  I believe golf clubs are designed to introduce spin that is perpendicular to the line of travel.  This helps to add lift and range.  

The pressure for the unpatched balls would be much less explaining the less than stellar range.  The heaver balls should be more accurate.

[GGaskill]

By patching the balls, I think you are getting zero spin and, consequently, the knuckleball performance.  Since you appear to need something to seal the bore, try using a wad between the golf ball and powder so the ball is free to pick up spin from the bore but the powder gasses are restrained.  You may even have to go with sabots to confine the powder better.

[intoodeep]

30/40,

 Did you by chance retrieve any of the golfballs? I am curious as to the condition of them.

 I have made a golfball mortar with a nice fit (Boy, do they fly....   ). Anyway, the last time I was in the desert launching a few balls I noticed that a couple of the balls (that I was able to find) had a slight buldge in them.  What I am wondering is. Since, golfballs are made of plastic and rubber, is that maybe the heat from firing them is just enough to slightly deform them. I will need to get back out and make an extra effort to find most of the balls next time.

 Also, I have heard that the golfballs will start to self destruct at a certain velocity. Since, I heard this from "Cannonmaker" maybe he could let us know those details as I can't remember them....

[Cat Whisperer]

30/40 -

Your experience is common.  I've recovered a few with powder burns on exactly one side, indicating no major rolling in the barrel (perhaps later).

Hooking and slicing is par for the course (pun intended).  

I've noticed more curve in the line of flight with higher velocities.

AND, WELCOME to the forum!

Any pictures?

[bloomautomatic]

I've launched a lot of golf balls and have the same results.  I've watched some go up and curve left then curve back to the right.  The no spin thing seems to do interesting things to them.  Also, we were in a valley, so possibly when they cleared the hills they may have had some different wind acting on them.  Golf balls are going to be more susceptible to wind than a heavier ball.

Vince

[Cannonmaker]

intoodeep,
I have been told a couple of times that the termonal velocity of a golf ball is around 2250 fps.  These people did seem to be quit knowlegable of the subject at hand.  I have conagraphed them at 1380 fps and they seem to be allright at that speed.[/quote]

[Powder keg]

A friend told me that if you shoot 2 golfballs they will fly straight. I haven't tried it yet though.

Later

[Double D]

Could it be the ballistic coefficient?

Sounds like its time get one of our sponsors to make you a ball mould.

I would be inclined at golf ball diameters to try cast some zinc balls. 1.7 inches is getting into the area where lead is to heavy and will  over stress everything.

As George said also use a sabot.

Another thing to do is got the resource list.  I think we have a guy selling golf ball size lead balls. Buy a few and see it they work.  

What ever you do lead or zinc refer to the safe loads chart that we now have up courtesy of Matt Switlik and don't exceed the loads on that chart.

[Cat Whisperer]

A friend told me that if you shoot 2 golfballs they will fly straight. I haven't tried it yet though.

Later

Sometimes.

The first one goes further, though.

[Cat Whisperer]

One could mark one half of the little dimpled sphere with paint or majic marker - it would be 'easy' to see if it were spinning.

[jeeper1]

According to this article http://fi.edu/wright/again/wings.avkids.com/wings.avkids.com/Book/Sports/instructor/golf-01.html
the dimples are there to induce lift when the ball spins in the correct direction (the axis of the spin is horizontal and the top of the ball is coming towards the shooter). If the axis of spin is any other way, the ball can go any direction.
Therefore to get maximum distance and straightness
from each shot there needs to be a slight groove cut into the bottom of the barrel from chamber to muzzle to let a small amount of burning gasses to blow by the ball and induce spin in the proper direction.

[Cat Whisperer]

Jeeper1 -

THANKS!  I knew there was a reason for the dimples, but was benighted as to the acutual physics behind how they worked.  Now we know.

[guardsgunner]

This mat sound like a dumb idea, but, try dipping the golf ball in wax.
It will enlarge it and fill the dimples.

[30/40]

I have emailed the person that is supposed to make lead balls the size of golf balls, but both his email addresses are bad.  I have emailed 3 places that make cannon ball sinker molds, but no replies.  One gentleman said he could make a mold for me for $150 and it would take 2 months before he could get to it.  I hope to get a cannon ball sinker mold, and a retired welder friend said he would weld up the eyelet holes for me.  

I have retrieved some golf balls.  They appear to have a rounded portion that has been blackened by the powder.  All appear round.

[Rickk]

there is a chart of sizes vs weights for "Do-it" brand molds up to 1.69" (16 ounces) located here :

http://www.merricktackle.com/PDF/Tackle/molds.pdf

and also here:

http://www.luremaking.com/catalogue/catalogue-index/catalogue-items/molds/cannon_ball_sinker_molds.htm


for molds over 1# look for diameter info here:

http://www.luremaking.com/catalogue/catalogue-index/catalogue-items/molds/cannonball-large_mold_ind.htm

I have the 2 # mold... runs about 2.11" with my calipers, just like the chart says it should. The protrousions caused by the recesses for the wires come off easily with just a fingernail, so welding them up probably isn't needed. The mold is aluminum, so welding is a hastle anyway.

JB-weld (epoxy) might do the job just as well if you wanted to try it... I have heard of it being used in alot worse applications and somehow it holds up.

[Double D]

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These are our board sponsors.  Contact them for you needs.

Fishing sinkers  make fair cannonballs, but if you aren't happy with the way a golf ball flies, I don't think you will be happy with a fishing sinker either.  

My experience is that they don't cast a truely round ball.

Besides you can order a custom mold from the sponsors to more closely fit your cannon than a sinker mould.

I think in the long run you will find it well worth the investment.

[Rickk]

The sinker mold I got is pretty round, it was fairly cheap, in stock, but somewhat undersize.

I also have a mold from one of the members here on order, and I know it will fit a lot tighter. It costs more (expected...custom always does), and I was told right up front that it would be 6 or maybe more weeks before my order would come up in queue.

So, there is the quick/cheap/maybe-compromise or the custom that will take a while, cost what custom costs, and maybe fit better. Depending on your needs you may want to order both. The cheaper Do-it mold in approximately your size has two cavities... a 1.54 and a 1.69 cavity (both are possibilties for a golf ball substitute) , and you are only risking $40. It will take you thru the wait for the custom mold.

One last thing... the nice thing about a custom mold is that you get to pick the size rather than just taking what they crank out of the assembly line. That means that you can get a lot tighter fit in your bore (less blowby, bouncing). While that means that it will probably work better, there is also more chance of having a damaged ball get stuck in the bore while loading. While you are ordering that custom mold, ask about a ball gauge as well. That way you can roll each ball thru the gauge just prior to loading to check for damaged balls.

[Double D]

Excellent point Rick aboutr the ball gauge.

[GGaskill]

If you're still using golf balls, you might consider placing a nail at the top of the bore at the muzzle that just contacts the balls.  The idea is that contact with the nail point will give the ball some backspin which will give you lift as well as a uniform spin orientation from shot to shot.  

If you are willing to modify your barrel, the nail could be put just short of the end or a pointed screw could be used, which would be self-retaining and adjustable.

I haven't ever tested this so it would be an experiment.

[jeeper1]

It would have to be removable for loading and the first shot would bend it.

[Rickk]

Maybe try e-mailing topflite and ask their engineers??

I am an engineer (electrical), and where I work all profitable work stops when we get a really screwy question that hasn't been asked before.

They might enjoy giving the advice, and if it is free, it couldn't hurt.

[Cat Whisperer]

Rick -

What a fabulous idea!  I'll bet there are a dozen or so major manufacturers of golf balls (and numerous patents).

What an opportunity for them - an endorsement of (xxxxxx  <-- insert brand of cannon or mortar) coupled with their (perhaps their competitor's) golf balls.  "Top Flight goes 20% further than the competition with standard charges of FFg Goex (or other brand of choice)!"

You might get lucky and get a real reply, but I would expect more of a disclaimer and warning not to use their product as a projectile propelled by black powder.

[Rickk]

Maybe, maybe not...

the question will get forwarded to engineering (as are all hard questions).

Engineers hate lawyers and legal stuff, and love to do something less boring than whatever they are doing at the moment.

My guess is that the reply will be sent long before any liability warning bell rings in the senders mind :-)

[guardsgunner]

Rickk, it would be worth it to me,just knowing that now a large number of golfers will be standing it the sun , perplexed with the new disclaimer, max charge and velosity warnings which would then encompass his golf ball. :-D

[Rickk]

I live 2 miles from 3 golfcourses....
nah... bad thoughts... stop stop

[Terry C.]

BOOM!!!


"Fore!"

[Rickk]

Maybe this can lead to a totally new sport.

I already have an appropriate golf cart for hauling the mortars ... er... I mean "clubs" (what clubs? we don't actually have "clubs". )

http://www.lioby.com/im/golfcart/cart1.jpg  <--- picture

http://www.lioby.com/im/golfcart/golfcart.mpg  <--- 6 meg video - 6 meg... If you are on dialup, you were warned.

[Victor3]

If you're still using golf balls, you might consider placing a nail at the top of the bore at the muzzle that just contacts the balls.  The idea is that contact with the nail point will give the ball some backspin which will give you lift as well as a uniform spin orientation from shot to shot.  

If you are willing to modify your barrel, the nail could be put just short of the end or a pointed screw could be used, which would be self-retaining and adjustable.

I haven't ever tested this so it would be an experiment.

This is probably the best suggestion. I don't have experience with shooting golf balls with powder, but I did make a Co2 golf ball "bazooka" that I learned some things from...



There is a ring machined in the chamber that holds the ball in place. When this ring was full circumference in the chamber, the balls went all over the place due to the spin that was induced non-uniformly as the ball squeezed past the chamber ring. Removing all but a section at the top of the ring induced backspin uniformly, made the thing more accurate and gave it more range.

Paintballers and airsoft guys have long known that bending their bbls DOWNWARD slightly puts a backspin on their balls and gives increased range. I read some years ago of testing done in the 1800's on smootbore muskets that came to the same conclusion.

BTW, I found that glof balls are not of uniform "caliber" from one brand to another...

[Cat Whisperer]

Victor - Thanks for the info.  Well written, good stuff - interesting that we are experiencing (again) what folks dealt with over a hundred years ago.