What is ogive?

[Eaglet]

He said it's that part of the bullet between the full diameter and point.

+1

When it comes to bullets that's it!!!!

The ogive is that section from point of tangency in this photo to the tip of the bullet.
That whole section is the ogive.

 

[MontanaRifleman]

+1

When it comes to bullets that's it!!!!

The ogive is that section from point of tangency in this photo to the tip of the bullet.
That whole section is the ogive.

Yeah... the curvy part... right???

 

[Eaglet]

Yeah... the curvy part... right???

Right??? YES!!! Bullet ogive are sections of circular arcs. (In the profile of the picture)

 

[boomtube]

"It's like uhhh... the curvy part of the bullet between the bearing surface (outer shank) and the tip of the bullet "

Originally Posted by MontanaRifleman
Yeah... the curvy part... right???

"Right??? YES!!! Bullet ogive are sections of circular arcs. (In the profile of the picture) "


Well, it's usually curved. But then some guy would come along and point out that section doesn't need to be curved to be an ogive.

Decreasing circular sections? Yes, but even that gets a bit more technical than it need be. AND, from what I read on the net, it's clear that some think the "ogive" is ONLY the circle that matches the bore diameter (rifleing contact point), ignoring all the rest of it. Oh well, it's a harmless error.

 

[Jinx-)]

There are more to it then just curvy side, I did some research and here what I came up with:

Most supersonic aircraft, rockets, and missiles use a nose shape very similar to a cone but a little more rounded to provide more internal volume. This shape is called an ogive (pronounced "oh-zheeve" or "oh-zhive"). The faster the vehicle is designed to go, the more pointed the ideal aerodynamic nose shape becomes.

The ideal nose shape for a projectile that minimizes its drag and maximizes its altitude depends on how fast the projectile is designed to travel

Tangent ogive
Next to a simple cone, the tangent ogive shape is the most familiar in hobby rocketry. The profile of this shape is formed by a segment of a circle such that the rocket body is tangent to the curve of the nose cone at its base; and the base is on the radius of the circle. The popularity of this shape is largely due to the ease of constructing its profile.

The radius of the circle that forms the ogive is called the Ogive Radius ρ and it is related to the length and base radius of the nose cone as expressed by the formula : ρ = (R^2 + L^2) / 2R The radius y at any point x, as x varies from 0 to L is: y = sqrt(ρ^2 - (x - L)^2)+R - ρ The nose cone length, L, must be equal to, or less than the Ogive Radius ρ. If they are equal, then the shape is a hemisphere.

Secant ogive
The profile of this shape is also formed by a segment of a circle, but the base of the shape is not on the radius of the circle defined by the ogive radius. The rocket body will not be tangent to the curve of the nose at its base. The Ogive Radius ρ is not determined by R and L (as it is for a tangent ogive), but rather is one of the factors to be chosen to define the nose shape. If the chosen Ogive Radius of a Secant Ogive is greater than the Ogive Radius of a Tangent Ogive with the same R and L, then the resulting Secant Ogive appears as a Tangent Ogive with a portion of the base truncated.


ρ > {R^2 + L^2 / 2R} and alpha = arctan ({R / L}) - arccos ({sqrt{L^2+R^2} / 2ρ})

If the chosen ρ is less than the tangent ogive ρ, then the result will be a Secant Ogive that bulges out to a maximum diameter that is greater than the base diameter. The classic example of this shape is the nose cone of the Honest John. Also, the chosen ogive radius must be greater than twice the length of the nose cone.

Told you just get bullet comparator...

 

[Firearrow]

Finally a redneck answer that I can understand, and it even has a picture. Still alittle fuzzy. Actually I just wanted to know how to measure from the base of the casing to the ogive, instead of to the tip of the bullet. Is a bullet compareitor the best way? Looking for the best way to measure OAL.

 

[RockyMtnMT]

I figured I would revive this old thread and also start a discussion about base to ogive measuring.

There is good info here to define ogive. I many have been mislead as to what an ogive is.

 

[Edd]

I think bullet makers should define the Ogive as the spot on the bullet that is bore diameter.

 

[Mikecr]

It doesn't help. Ogive datum (as a meaningful standard) is still undefined. There is a lot of math involved in determining a real 'land contact' point, and while ogives vary in radius, and land angle vary more & more with every shot down the tube.
What you measure with BTO provides nothing regarding the individual drag sections. There is a lot of math involved in calculating drag from each section, if carefully determined. Then there is the measure & math behind the ogive itself, including meplat diameter. And aerodynamics science does not rely on calculations alone, but also on validating testing.

So there are no credible actions to be taken from a mere BTO measure.
It's silly

 

[J E Custom]

Here is a good description of both types of ojive.

https://www.google.com/search?q=bul...4KHdcWDXMQ9QEwAXoECAUQCQ#imgrc=iaaS5J3-UJXXKM:

J E CUSTOM

 

[RockyMtnMT]

The simplest way I can put it is the ogive is the shape of the nose.

Base to ogive measuring tools will give you false length readings based on slight dia variances that are shown exponentially in length.

 

[MNbogboy]

It doesn't help. Ogive datum (as a meaningful standard) is still undefined. There is a lot of math involved in determining a real 'land contact' point, and while ogives vary in radius, and land angle vary more & more with every shot down the tube.
What you measure with BTO provides nothing regarding the individual drag sections. There is a lot of math involved in calculating drag from each section, if carefully determined. Then there is the measure & math behind the ogive itself, including meplat diameter. And aerodynamics science does not rely on calculations alone, but also on validating testing.

So there are no credible actions to be taken from a mere BTO measure.
It's silly

Agreeing here on above.
What is important is whatever BTO you calculate and measure with your test bullet, on a given day, is your baseline for your rifle and your rifle only.
From that baseline you can set distance from the lands on handloads or determine relative throat erosion at a later date providing you use the same test bullet.
Never rely on someone else's results per mikecr's explantion.

 

[MNbogboy]

In addition the test bullet must be at least similar to the rest of the bullets in a given lot. Bullet sorting (bullet base to ogive) and averaging recommended before choosing your test bullet. Keep in mind bullet lot change will also change bullets dimensionally (possible need for additional load development).
Finally all bullet types/brands require their own BTO baseline.

 

[RockyMtnMT]

I will speak only for our bullets. They are for the most part tangent ogive. We hold a .0002" tolerance in the dia. As you slide a ring down the ogive of the bullet and get closer to the shoulder the more parallel the ogive gets to the baring surface. A diff of .0002" from one bullet to the next will allow the measuring devise to move much father down the ogive toward the shoulder on the smaller of the two than the actual .0002" dia diff. The reason for these devises is to find a better place to measure than to this actual overall length die to the fact that swaged bullets become more imperfect closer to the meplat from the swaging process.

I think a better way to measure is to uniform the meplat on the swaged bullets and measure actual coal or just measure coal on the machines bullet.

Ogive measuring devices become a tale chasing effort.