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Joined: Dec 2000
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Campfire Ranger
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Campfire Ranger
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I don't know. I don't how much Richard has, and I don't how much I have. Or which has the later date. (I suspect that Richard's is probably more up-to-date than mine.)
"Good enough" isn't.
Always take your responsibilities seriously but never yourself.
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Joined: Dec 2008
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Campfire Regular
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Campfire Regular
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I don't know. I don't how much Richard has, and I don't how much I have. Or which has the later date. (I suspect that Richard's is probably more up-to-date than mine.) This one is dated 4/13/2010
It's not that Liberals are unwilling to listen to another point of view, they are just simply amazed that another one exists.
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Joined: Oct 2008
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Campfire Regular
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Campfire Regular
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What I have is the newly-printed 2nd Edition of the book. This edition includes the corrections from that online errata list. It's a worthwhile 'upgrade' for owners of the 1st Edition, IMO.
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Joined: Dec 2000
Posts: 29,348
Campfire Ranger
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Campfire Ranger
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� It'd be interesting to hear/read the advantages of the secant ogive. � It would be interesting to hear what the interior ballistic advantages of secants are. � Basically, the secant ogive gives you the front end of a larger bullet's tangent ogive � that part of a .257 or .285 tangent ogive, say, on a .224 bullet � for a better ballistic coefficient and nearly the same mass and length as a bullet of the same diameter with a tangent ogive. A secant-ogive bullet is at it's best, of course, in a barrel with the leade reamed for it. A 75-grain .224 A-max in my .220 Howell, for example, engages the rifling when its cylindrical shank comes out of the case neck. The tangent ogive of a good bullet commonly curves along about an eight-caliber radius. A corresponding secant-ogive bullet curves on a longer radius but uses only the front portion of a larger bullet's tangent ogive. On a bullet of the same or shorter over-all length, it doesn't need the tighter twist that a longer bullet would need. A series of good drawings would make all this very clear, of course. I can't draw it since a couple of computer crashes cost me the old version of AutoCAD that I used to make all the drawings in my big cartridge book. I can't afford any of the later versions of AutoCAD, and I probably wouldn't know how to use it, anyway. Obsolescence is expensive! Let's see whether I can explain this more clearly another way, just a teensy bit over-simplified. � A 10- or 12-radius tangent ogive on any bullet would be much more aerodynamic than an 8-radius tangent ogive, but it'd make the bullet 'way too long to stabilize in the typical twist of a barrel of that caliber. � The eight-radius tangent ogive of, say, a .285 bullet would equal a 10.1786-radius ogive of, say, a .224 bullet (if I've done the math right). � Picture that bigger ogive as a curve-sided cone. � Somewhere between its 0.285 base and its near-0.0 tip, there's a place where it's 0.224 in diameter. � Now imagine that forward section of the 0.285 ogive � from where it's 0.224 in diameter out to its tip � on the forward end of a 0.224 shank. Clearer now? It'd be dog-simple to draw, but I can't, so I have to depend on your ability to visualize it from a word description. Hope this helps.
"Good enough" isn't.
Always take your responsibilities seriously but never yourself.
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Posts: 6,960
Campfire Tracker
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Campfire Tracker
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Ken, that's a very clear and simple explanation, thanks.
Mark
NRA Life Member
Anytime anyone kicks cancers azz is a good day!
~Molɔ̀ːn Labé Skýla~
Oh The Drama!
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Yes, I understand. One thing I find tremendously interesting is how the drag curve changes as one lengthens the radius of the circle which describes the ogive shape. Basically, a secant ogive of radius Rt/R=0.5 is more or less the minimum-drag shape at supersonic speeds, of circular-radius ogives. However, this nose shape exhibits much higher drag at low supersonic and into trans-sonic speed ranges. Naturally, we don't normally concern ourselves with transonic performance in a hunting context, but for some sports, for example, this may become a factor.
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Joined: Dec 2000
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Campfire Ranger
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Campfire Ranger
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That of course brings up an entirely different matter � giving the bullet enough muzzle velocity to enable it to maintain supersonic speed out to the maximum desired or practical range.
Then that matter leads us into other discussions � what's reasonable to expect or to aim for in situations X, Y, and Z, etc � far beyond the question of ogive shape.
Muzzle velocity loses a lot of its allure when you look into what the bullet is doing 'way out there where it meets meat or pierces paper.
"Good enough" isn't.
Always take your responsibilities seriously but never yourself.
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Joined: Oct 2008
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Campfire Regular
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That of course brings up an entirely different matter � giving the bullet enough muzzle velocity to enable it to maintain supersonic speed out to the maximum desired or practical range. Yes. Or, choosing a different nose shape that is better suited to a wider operating envelope. Information is great for the options and choices it opens up to us. As you say, there is much beyond the scope of an ogive shape discussion.
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Joined: Jun 2010
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Campfire Tracker
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Do you have the errata for the McCoy book? The publisher pushed the book into print before Bob had finished correcting the galleys, and Bob died before he could complete the errata. Bob's colleagues and collaborators, Don Miller and others, took-up the compilation � which took some time and may still be incomplete. (My friend Don has died, too, alas! He was the head of the errata project, I think.)  Send me (ken1931  gilanet.com) your e-mail address, with a reminder, and I'll send you the errata that I have. Ken, I believe you are correct about Don Miller heading the errata project. Dr. Miller was another of the great men who has moved on to the next age. For those who haven't seen it, here's his Obituary. Many on these pages know that one of Dr. Miller's many lasting contributions is the Miller stability formula that's used to know what twist rate is required to stabilize a bullet.
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Campfire Kahuna
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Campfire Kahuna
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I didn't know Don passed away.
We met maybe eight years ago at the SHOT Show, when Don asked if I'd be there and if so, if we could meet. We did and had a great conversation. At the time one of the things he was working on was my empirically formulated 4-to-1 Formula: Any difference in powder capacity in a centerfire rifle case of rhe SAME caliber at the SAME pressure results in 1/4 that difference in muzzle velocity, with the same bullet.
Don figured out why the formula worked--at least closely enough for practical purposes--and was gracious enough to ask to cite my original work when publishing his article. Of course I said GREAT!
We saw each other at various other gatherings over the next few years, and always had very interesting and enjoyable conversations, mostly about ballistics but sometimes about life in general, and kept in contact with e-mails until a couple of years ago.
He was a gentleman and a scholar, in the best sense of both words.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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