welderman- I think we could calculate the rotational speed at 40 yards if we assumed that the rotational speed decreased at the same rate as the forward motion of the target. The problem is, I suspect this would be a false assumption. The air resistance to the forward motion of the target would be greater than the air resistance against the rotary motion.
MrkSLC- Your question of why is simple to answer. Questions like this one might allow us to learn something new and we never know when new knowledge might become useful. Also, some believe mental exercise is as important to the brain as physical exercise is to the rest of the body. Some of us are lacking in mental exercise or physical exercise or both.
No big mystery here. I am planning to take high speed photos of shot strings as they hit a target. A moving target is more difficult to photograph, but a stationary target rotating at about the same velocity as an actual target would not be too difficult. I need to know the rotation speed of an actual target so I know where to set the motor controller. Tom S. (welderman)
Hi Tom, For a bunker shooter, knowing the rotational speed of the target is important. Some foreign made traps , seen infrequently here but more frequently overseas, throw low RPM targets that are noticably harder to break and require more choke. There is a formula to compute rpm's. Please e-mail me. I am very interested in your experiment. Les
I think the initial rotation of the target could be calculated from the speed of the tip of the arm, not the length of the arm. That speed can be measured with my radar gun. This would require the additional assumption that the target is not slipping as it travels across the rubber and I think that some slipping takes place is a reasonable assumption.
As long as we are making unconfirmed assumptions, how about these two? The rate that target rotation slows is linear. Then a rotating target could be dropped into a fluid (water) and the time required for the rotation to stop could be measured. This time could then be adjusted for the density difference between water and air and an estimate of the time for the target to stop rotating in air could be extrapolated. From this time, the initial rotary speed of the target could be adjusted for the time the target requires to travel 40 yards. Of course, if the assumptions are incorrect this exercise would be meaningless.
If you discount slippage, the formula for spin is easy; it's just how fast a target is turning when it's rolling 67 ft/sec for American trap. (Be sure to watch for the seconds-to-minute conversion easily left out.)
But you can't ignore slippage, in my opinion (Brindle, in American Rifleman, even said that targets can spin too fast.)
So figure somewhere under 3000 rpm off the arm, and a bit (what's slowing it down?) slower, RPM-wise, when hit.
Tom, wouldn't it be easy to paint a thin silver stripe on some targets and using the sort of high shutter speed available on many digital cameras, see how wide the stripe appears in the photo? You have your "scale", the target size, right in the picture, after all.
Pat, Forget reality, I don't have clue where you're at.LOL. What color is the water you are using, it's too early in the day for that amber liquid.More seriously, there does seem to be a significant difference in spin rate from different machines. I think that also contributes to being able to keep a more consistant target into the wind. Please don't ask me WHY Neil, because I don't have a clue, only my impression. It was an easy process,and always the first thing you did setting targets for a large shoot on the old WW handsets, was to wipe the arm with an abrasive to insure good spin rather than "sliders". Having said that, the arms on the new automatics in use today are not as easy to access for cleaning. There are also a few different materials in use today.I think determining the actual spin rate would be quite difficult to do with any certainty.Having said all that, I haven't contributed beans toward a positive conclusion to the discussion have I.But I do agree a clean arm to promote spin rate contributes to a quality target. Have fun in the sunny South next week fellows. Bob
Yes, the down range rotation could be measured with a strobe, or streak technique. For now, I'm interested in bracketing the possibilities. My White Flyer targets measure 4.23" diameter which would be 1.107 feet per revolution. At 67 ft/sec with no slippage, it would be spinning at 3630 rpm off the arm. For now I will guess 1000-2500 rpm down range. If anyone comes up with better numbers, please let us know. At least now I will be able to select an appropriate motor. Tom S. (welderman)
Gary, a static clay is much harder to break when it's sitting still. I'm working on a device to spin a target forward and reverse so I can shoot some stationary targets to check out a few things. Reading breaks, patterns, shot sizes and so forth at the same average distances I break my birds. Hap
Jim410 I sent U a note."
Another thing that's always been a question for me is, "reading the break" on clays. This will definitely answer that question also! Hap
Bob, as you go through this year's rulebook, you will see that I'm making progress in getting rid of unrealistic accuracy (targets 4.125 inches) and the metric stuff got axed a year or two ago to keep people like you from making things so difficult.
Thanks Neil, I didn't know the bird was powered at the band. That ups the perfect friction example to 4084 rpm. Why don"t they mold some gear teeth into the band and throw them with a rack instead of a rubber clad arm? It would make for fewer assumptions on my part. Another way might be to run the bird hard against a surface prior to throwing it, like a pe-launch burn-out. Tom S.(welderman)
Bob_K, how about a clay sitting motionless? Without rotation, they are much harder to break. Then you read the break or chip as being shot too far in front of or behind the bird? Sorry I didn't make it more clear. Hap
Neil,Thank you for your efforts and intuitive reply. I guess your answer only begs the question, why in the world would any intelligent, sane person want to be President of a bunch of Nit-Wits like us. Thanks again, Bob Hawkes