Author Topic: Magnus effect (Read 2445 times)

kevthebassman · « **Reply #30 on:** February 14, 2009, 01:25:38 PM »

I think you'd only need a few inches of it at the muzzle, it ought to be something you could accomplish with a steady hand and a cutting wheel on an air grinder.

Disclaimer: This advice is worth what you paid for it!

dan610324 · « **Reply #31 on:** February 14, 2009, 01:48:56 PM »

but aint you thinking backwards now ??
you cant grind the ribbing , you must add something .
how else would it come in contact with the golfball ??
if you have a 1,75 inch bore you cand add grinded ribbing .
this will just do nothing .
you must add something that will reduce the bore diameter . you cant take away material .

sorry if this is an odd explenation , but my english skills aint good enough for me to explain this in any better way .

kevthebassman · « **Reply #32 on:** February 14, 2009, 01:56:47 PM »

I see what you're saying. I still think it may produce the desired effect. But, now that you mention it, if one had a welder, you could lay down a few "speed bumps" at the muzzle, then grind to desired height.

dan610324 · « **Reply #33 on:** February 14, 2009, 02:10:34 PM »

that should do it .
or at least would do it .

GGaskill · « **Reply #34 on:** February 16, 2009, 08:16:16 PM »

But, now that you mention it, if one had a welder, you could lay down a few "speed bumps" at the muzzle ...

Good idea. Much less work than drilling and tapping for set screws, although not as adjustable. I may give that a try.

Victor3 · « **Reply #35 on:** February 17, 2009, 03:27:19 AM »

Quote from: GGaskill on February 16, 2009, 08:16:16 PM

But, now that you mention it, if one had a welder, you could lay down a few "speed bumps" at the muzzle ...

Good idea. Much less work than drilling and tapping for set screws, although not as adjustable. I may give that a try.

I'd thought of welding the projections in, but as you say, they would lack the 'tune-ability' of screws. Screws could be set into position with a jam nut, or you could use those locking set screws with the plastic pellet in the threads. Tips of screws can also be easily modified into points, radii, etc.

I'm thinking now that two sets of screws (one set right near the muzzle and one about 2" back, for a total of four screws) might be better. The first set would 'rough in' the position of the ball in the bore and start the spin. The final set would add the finishing touch just before the ball exits.

Maybe...

dan610324 · « **Reply #36 on:** February 17, 2009, 03:53:18 AM »

not a bad idea , could be worth testing .

2 or 3 mounted half an inch from the muzzle ,
then another 2 or 3 , 2 inch further into the barrel .

with radius tip and a locking nut that it cant change position .

Artilleryman · « **Reply #37 on:** February 17, 2009, 05:17:37 AM »

I have been following this thread and trying to make sense of it. I will be the first to say that I do not have any experience with shooting golf balls, and can only relate what I know about large smoothbore cannons. In them the ball bounces in the bore supposedly three times before it leaves the gun, and the movement or direction the round shot takes has a lot to due with uneven density in the projectile.

Now as I understand this thread (I may be wrong) the idea is to put a back spin on the golf ball to improve accuracy and distance. My question is, what kind of spin does it have on it in the first place, and how did you figure it out?

Cat Whisperer · « **Reply #38 on:** February 17, 2009, 06:27:23 AM »

Good questions.
My experience is with mortars.
Watching them - the slow spin is obvious. I've fired a few cannons many times but not seen many rounds flying.

Using a golfball mortar, the recovered round is black on one side, white on the other - indicating to me not much spin if any.

With lots of powder the ball hooks or slices.

Theory holds that with backspin it does so less.

Artilleryman · « **Reply #39 on:** February 17, 2009, 06:43:37 AM »

Quote from: Cat Whisperer on February 17, 2009, 06:27:23 AM

Good questions.
My experience is with mortars.
Watching them - the slow spin is obvious. I've fired a few cannons many times but not seen many rounds flying.

Using a golfball mortar, the recovered round is black on one side, white on the other - indicating to me not much spin if any.

With lots of powder the ball hooks or slices.
Theory holds that with backspin it does so less.

I have experience with 24 pdr coehorns and an 8 inch siege mortar. You are right the shell does have a slow spin. The shells recovered usually have one side blackened. So from your description of the golf ball I would say it spins also. What I have never really paid attention to is which way the shells from my mortars spin. I guess someone with high speed camera equipment will have to give us the evidence we need.

Cannoneer · « **Reply #40 on:** February 17, 2009, 06:44:17 AM »

Quote

My question is, what kind of spin does it have on it in the first place, and how did you figure it out?

Norm, other than some type of theoretical formula, the only empirical (and really provable) way to find out, that I can think of, would be to use the same thing that modern ammunition manufacturers use, namely super slo-mo film lit by high intensity strobes, that can readily capture the movements of the projectile in flight.

Well Norm, I guess when one sees the red message flash, that tells a person another member has made a post, that it would be a good idea to read that post before making his own.

GGaskill · « **Reply #41 on:** February 17, 2009, 02:39:20 PM »

I make no claim to having seen the spin itself. I have observed that a golf ball will curve to the right on one shot; curve to the left on the next; hit the ground at fifty yards on the next and 150 after that; all with the same powder charge. I interpret those observations as saying that the ball is spinning one direction on the first shot and almost the opposite on the second. Since there is nothing to force a particular spin on the shot, this interpretation seems reasonable.

It is currently my plan to add a couple of spots of weld just inside the muzzle to my golf ball mountain howitzer and see what effect that has the next time I take it to the range.

subdjoe · « **Reply #42 on:** February 18, 2009, 04:16:11 AM »

Instead of doing anything to the bore itself, couldn't you mount a bracket at the muzzle to hold some pins or brushes? Or maybe something like a curved comb out of spring steel. Just a thought.

dan610324 · « **Reply #43 on:** February 18, 2009, 06:43:53 AM »

that one could work , but its also possible that it just will help to change the balls direction to the ground as it doesnt have any support beneth the ball .

Cat Whisperer · « **Reply #44 on:** February 18, 2009, 12:14:19 PM »

Quote from: subdjoe on February 18, 2009, 04:16:11 AM

Instead of doing anything to the bore itself, couldn't you mount a bracket at the muzzle to hold some pins or brushes? Or maybe something like a curved comb out of spring steel. Just a thought.

A 'bracket' under the barrel, close to the line of flight should be built VERY strongly as the pressure is strong enough to snap an inch board (I know).

If there's a baffle just under the ball at the end of the barrel there would be SOME pressure redirected. Effect ? who knows? It might just deflect it up, it might add back spin.

GGaskill · « **Reply #45 on:** February 18, 2009, 02:47:12 PM »

Well, one experiment at a time. If the welded bits don't work, I will try something else.

dan610324 · « **Reply #46 on:** February 18, 2009, 03:21:19 PM »

cw , I know that the russian khalashnikov have an very odd muzzle shape , but I dont know why .
at least it cant be to produce a backspinn on the bullets

but there must be a reason to why they are shaped as they are ,
so maybe the idea to create the backspinn outside the barrel aint that wrong .

Cat Whisperer · « **Reply #47 on:** February 18, 2009, 03:48:55 PM »

Quote from: dan610324 on February 18, 2009, 03:21:19 PM

cw , I know that the russian khalashnikov have an very odd muzzle shape , but I dont know why .
at least it cant be to produce a backspinn on the bullets

but there must be a reason to why they are shaped as they are ,
so maybe the idea to create the backspinn outside the barrel aint that wrong .

My understanding is that the bevel is to deflect some of the presure to push the muzzle down. It is rotated to one side to keep the push opposing the tendency of the muzzle to climb to one side.

My thought is that the push can be 'tuned' to an effect desired on the sphere. There is a definite effect if the base of a flat-based bullet is not even - it will disrupt the flight of the bullet causing larger groups (if randomly oriented) or it will move the group if oriented the same way each time (see Dr. Franklin Mann's book: The bullet's flight published in the 1920's.)

dan610324 · « **Reply #48 on:** February 19, 2009, 11:27:58 AM »

now it popped up a new idea in my head , or maybe a combination of ideas .

think a coupple of set screws or some weld in the barrel , when the ball passed that point in the barrel you open it up in the bottom to have the expanding gasses to escape under the golfball , it could help to create an better spin as you still have an short support on top of the ball .

see sketch below

crazy or not , I dont know .
just brainstorming now .

Victor3 · « **Reply #49 on:** February 20, 2009, 03:54:31 AM »

What effect (other than the Magnus) could cause a golf ball to exhibit wild trajectories?

I think that the word "theory" here might not be appropriate to descibe what's happening to our cannon ammo in flight - I can't imagine anything other than spin that would account for what we've seen...

Double D · « **Reply #50 on:** February 20, 2009, 01:40:21 PM »

How much effect does deformation, then rebound back to form play? Do you your golf balls hook and slice more or less with increase/decrease in pressure?

Victor3 · « **Reply #51 on:** February 21, 2009, 01:19:58 AM »

Quote from: Double D on February 20, 2009, 01:40:21 PM

How much effect does deformation, then rebound back to form play? Do you your golf balls hook and slice more or less with increase/decrease in pressure?

After looking at several websites containing info on golf ball physics, all I can find concerning deformation is focused on either initial velocity off of the club face, or how much surface area of the ball will be in contact with it (either increasing or decreasing potential spin).

Since there doesn't seem to be anything discussed concerning deformation alone being related to trajectory, I assume it's not an issue.

However, something I learned is that that there are different "compression ratings" for golf balls. I always assumed that it was the same on all of them. This would be a factor for us; all balls should be of the same rating for any experimentation lest they be squished differently from one to another in the bore. Ambient temperature and age of the balls can cause compression variations too.

They also vary in diameter from one maker to another, and can have different dimple patterns that supposedly have an effect on lift.

So, a new pack of balls should be used to perform any test.