BUT...........
What exactly makes you think that the nose is riding high, (EXCEPT nennstiel-Ruprecht's questionable numbers/illustrations). What DRIVES the "nose high"....?
"Gyroscopic stability" right? It "wants" to keep going straight, right?
You're going to have to do a little experiment to understand some of this, because it's not all real "obvious". You'll need a bicycle front wheel and axle. It can still be attached to the bicycle, but holding it in your hands will work better.
Let the axle be the the initial axis of bullet rotation and the direction that the barrel is pointed. Have someone spin the wheel up to a good speed (fast enough so that you can feel the gyro action, but slow enough to be safe - an electric drill chuck held against the tread should do it). OK So you're standing there holding the spinning wheel (For grins and giggles make sure that it is spinning in the same direction as a bullet would be if traveling from your left to your right. Now try and pull your right hand toward you, as if your "bullet" had run into a right to left wind. Which way did your Bullet try to point? Up or down? Because it will only be one or the other depending upon which direction it was rotating. It is NOT just going to let you turn it without a fight.
IF THIS IS TRUE.....then the bullet does NOT always point directly into the airstream.....it DOES NOT search to center it's nose on the neutral wind vector. It in fact flies with it's nose well outside the neutral zone, SO FAR outside that it's presenting an "oblong profile" to the wind......thereby showing a decrease in BC because of it's larger presented frontal area.
A PROPERLY stabilized bullet will damp out these "wobbles" and keep the nose in the center of the shock wave like a top spinning on a sheet of saran wrap, and the nose WILL stay inside the "Zone" as you called it, and will not present an oblong profile. And so long as the arc of the trajectory is not too drastic, it will "nose over" and maintain a minimalist profile to the air field flow.
You will notice that in the specific example used - the rifle was launched at a 40° angle - now that is pretty drastic, and a lot to ask of a projectile that is steadily gaining in "stability" (Rotational velocity slows down MUCH slower than downrange velocity)
Somehow, what you're saying is that the concept of the bullet "balancing" on the apparent wind direction doesn't apply to a falling bullet?
I guess it would IF the "falling bullet" were spinning in excess of 160,000 to 220,000 RPM. I think Hatchers vertical firing tests had the bullet (the very few that were recovered) still spinning and still pointing upwards (no arcing trajectory to nose over into) when they landed.
IF THIS IS TRUE..... then why does the precessing nose find center on the horizontal plane BUT NOT ON THE VERTICAL??
Who said it "found center" on the horizontal? As it tries to nose over and follow the trajectory, the precession forces are side ways, not vertical. So a RH twist will "drift" one way, and a LH twist will "drift" the other way...even in a dead calm.
AND..... why does this proposed "lift force" work exactly OPPOSITE the force which drags a bullet off line horizontally?
I'm not at all sure of what you are trying to say here. Haven't seen a lot of bullets "drift" into the wind much...which looks to be what you are saying. But a well stabilized bullet WILL try and fly "into the wind" and will drift less than none which is not so well stabilized. But you also have to remember that "Ballistic Coefficient" is not a number calculated from the shape of the bullet - it's a measured and statistically averaged number obtained from actual test firings, and measuring the amount and rate of velocity loss. Everybody would like to treat it as a "Form Factor", but it's not. The reason folks can use it as a predictor, is because that's the way that particular bullet had behaved previously. And it does change, depending upon the velocity - The same bullet, launched at 3000fps will not exhibit the same BC as it would if launched at 1000 fps. But that's a common misconception that the BC is somehow a constant.
You're saying that a falling bullet shows a "lift force" (drag force acting "up"... hence "lift force?")
Nope. I said nothing of that sort.
you're saying that there's a drag component acting on the side the nose is pointing. Or is this "lift" force something other than a drag component? (your description belies this...)
There is the pressure on the point of the bullet which is off to one side of the flight path, which is what causes what they call the "Overturning Moment", and which the rotational momentum is resiting. If THAT's what you are talking about. And there is more pressure applied to the surface that is "more" broadside to the air flow field, which would tend to push the bullet toward the direction that the bullet is pointing.
YOU'RE SAYING that the bullet forges through the airstream slightly COCKED, it doesn't fly straight....
The better the stability, the more slight the offset, but OK, Yeah.
and that it's dragged into (it's trying to fall into) the low pressure area behind it's own nose.
When crossing
straight across a river in a motorboat - is this what keeps the nose pointed into the current?
It's flying crossways......a little.... at least on the VERTICAL plane.... in your model (and the ruprecht stuff) your bullet is popping a wheelie and falling through the air like Evel Kneivel, air on the bellypan.... nose UP, lift force UP.
right?
What about on the horizontal plane? Is the nose also pointed in the direction of drag? Lets say nose LEFT, drag LEFT?
al
Nose points up, bullet wants to continue in that direction, if it points left then yeah, it will fly left a bit, and then down for a bit, right for a bit, etc. In fact if you catch them on a clear day at a long enough range , you can see the bullets flying in little corkscrew flightpaths. Particularly if the humidity is just right enough to leave vapor trails. It's just how it works. Do the bicycle wheel experiment and you'll understand better. It ain't really about generating a vacuum anywhere.
