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Bullet lift, does it exist?

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Unread 12-09-2007, 12:17 PM
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Join Date: Oct 2005
Location: Michigan
Posts: 2,232
Brown dog,

What about the diagram? Doesn't it show that the axis of the bullet varies from the trajectory (up to 25 degrees from the chart)?

Unless I'm reading this incorrectly, it shows that the nose DOESN'T follow the trajectory.

Also, just curious what 'appropriately stabilized' is? In the real world, would you say a 300gr SMK spun at 1 revolution in 10" is Over, Under or appropriately stabilized for 3300fps? That's about 240,000 rpm. If it is in your definition Over Stabilized, then according to your last post
"or the spin rate is excessive, there WILL be a tendency for the projectile to retain its firing attitude, but such a projectile would be described as 'overstable'."

And we all agree.

from BRown Dog:
"Just popped back again, Your link actually states "Although, for the example shown in the drawing, the yaw of repose never exceeds half a degree" under the graph

I didn't see that, and was reading the label on the right as the angle of Yoaw of repose.

If some is good and more is better, then too much is just right.

My mind is a raging torrent, flooded with rivulets of thought, cascading into a waterfall of creative alternatives

Last edited by AJ Peacock; 12-09-2007 at 12:20 PM. Reason: to add clarification from BD's post.
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Unread 12-09-2007, 12:24 PM
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Join Date: Sep 2003
Location: Blighty
Posts: 637

Since my last post, I notice you've reworked your earlier post rather substantially.

Can't say I like the ad hominem stuff, but sadly that appears to be your style.

I won't degrade myself to match.

As regards the discussion; the piece you've added in about the overturning moment is spot on.

What you don't understand












I typed that slowly for you

Read my answer to AJ above. I doubt you'll understand, but the least you can do is try...isn't it?

Meanwhile please have a go at my earlier question:

In your simple "I once saw tracer burn out" understanding of ballistics;

enlighten me as to how point detonating impact fuzes function.

Base your answer on a shell fired at a 47 degree elevation.

Last edited by Brown Dog; 12-09-2007 at 12:29 PM.
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Unread 12-09-2007, 12:36 PM
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Join Date: Jun 2001
Location: Potomac River
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Smooth bore mortars are fin stabilized much like an arrow. If you put the drag force far behind the CG then you will achieve a slightly different result than with spin staiblized projectiles. As stated a 4.2 mortar is spin staiblized.

Fin stabilized projectiles have a whistle from the holes in the fins and you will know when to make your peace with your maker from the sound of the whistle, except sometimes you are just lucky and there is a lot of humus and it buries far into it before it detonates.

Unstable spin stabilized projectiles (known as "short rounds") actually tumble and you will also hear them coming and they make a "whoop, whoop, whoop" sound that gets louder as it comes closer. Your ears can actually calculate whether you are fixing to be meeting St Peter in the next few nanoseconds. Because they are tumbling they come at you pretty slow so you can jump right or left or just grit your teeth and pray. Once again, if you have been living right and eating your brocoli it may land badly and not detonate immediately, at which time you run like a sumbitch and wait a while and carefully ease back and get your rifle and ammo and gear. You do not go close to that round because St Peter might change his mind and decide he wants to see you.
The Smokin Fur Rifle Club
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Unread 12-09-2007, 12:39 PM
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Join Date: Sep 2003
Location: Blighty
Posts: 637

Another quote from your link (well, the page preceding the one linked)

"In other words, the maximum yaw angle, which occurs close to the muzzle, is damped out as the bullet moves on. After a traveling distance of a few thousand calibers, depending on the damping rate, the transient yaw angle practically approaches zero."

If you're happy with the concept described (of bullets being rather unstable at launch, but stabilising as they get further downrange).......Simply apply it to the apparent yaw angle produced by the trajectory falling away from the bullet....all that's happening is that that yaw is being gyroscopically damped out to match the changing just the same way that transient yaw is damped.

Hope that makes it a little clearer!
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Unread 12-09-2007, 02:03 PM
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Wow all this typing on such a mute subject must be at best for all involved an "exercise in futility".

So we have the mathematical equations, theory, and test data to make a 3500 yard first shot cold bore on a p-dog sized target with 1000% accuracy.

I think not it still takes a few shots to hit the dog despite whatever amount of spin drifting yaw dropping gravity pushing drag defying bullets we use lol.

Yall have fun, active lasers solve all this if you can afford them!!
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Unread 12-09-2007, 09:50 PM
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Location: on the rifle range in Utah
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Originally Posted by daveosok View Post
Wow all this typing on such a mute subject must be at best for all involved an "exercise in futility".
Yes. I don't even know what we're debating anymore or who is saying what. I thought this was a thread about bullet's rise above LOS in atmosphere as opposed to a bullet fired in a vacuum?
Find it
Range it
Click it
Pull it
Dump it

If it's not far, it's boring.
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Unread 12-09-2007, 11:03 PM
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Location: Memphis, TN. Soon to be Casper, WY.
Posts: 494
...and my head hurts from reading all this.
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