Radius of an ogive

[Grimstod]

Has anyone ever tried to calculate the radius of the ogive of there bullet. In the end I am trying to calculate the volume of the bullet but need the radius. And the manufacturer doesn't provide it. It's surplus am so what do you expect.
So far the internet and Google has been no help.

My motivation for this knowledge is, I would like to start build a database of info on many surplus and collectible bullets. Ammo collecting has sorta become an obsession lately. There are many bullets out there that are being lost or forgotten about.

 

[Dos XX]

http://www.accurateshooter.com/ballistics/tangent-vs-secant-vs-hybrid-ogive-bullets/

 

[Grimstod]

That's the difference between a tangent and secant ogive. What I need is the radius of that ogive. This is for a tangent ogive bullet however once I know how to do a tangent I can probably figure out how to do a secant ogive.

 

[mshelton]

What bullet is it?

Might be in the Litz book and I can look it up for you.

 

[XTR]

In the end I am trying to calculate the volume of the bullet ...

Drop it in a graduated cylinder half full of water.

 

[Outrider27]

Drop it in a graduated cylinder half full of water.

+1. Archimedes lives.....

 

[Eddie Harren]

Some people seem to make a career out of overcomplicating a situation.

 

[GerryM]

Is this what your looking for?
Length of a bullets ogive? = multiply ogive radius X2 Then 1/2 of bullet diameter {not caliber} Finally find the square root of that.
Gerry

 

[mikecr]

Grimstod, you know there is not a single radius but continual change along a bullet nose.
So the best way to calculate total volume is to calc volume of a number of slices within bullet length and add the volumes together.
Radius is just 1/2diameter at each slice, volume is Pi*R^2 times the thickness of each slice.
Your diameters minus jacket thickness*2 for internal volumes, etc..

 

[Syncrowave]

In the end I am trying to calculate the volume of the bullet ...

Drop it in a graduated cylinder half full of water.

Or do it with 10 or 100 and average it out by weight.

Pretty simple, really.

 

[BoydAllen]

If I remember correctly, one of the volumes of Ackley's books came with a chart that had drawings of various ogives that could be compared with the profile of a bullet, to determine what it's ogive's radius is. (I have it somewhere, but digging it out wouldn't do you any good.) I believe that many of the common bullet ogives are curved along a single radius. If I wanted to figure out an unknown bullet's ogive number was. I would first decide if it was secant or tangent, by inspection, and then I would carefully take a picture of it and print it as large as I could, then I would measure the shank diameter of the print, and draw arcs with various likely radii using multiples of the measurement of the picture. Then I would compare them to the picture to see which was the best fit. This essentially what the Ackley chart was to be used for, but because of digital photography, we can do it at a larger scale.

 

[mikecr]

Basically, it isn't easy..
But Ackley didn't have excel. He probably had Lotus

Today we can graph shapes & crunch a lot of numbers.
Here I slice a nose 1500 times along it's length to define it's shape. I can't take 1500 hundred measurements, but I can trial & error length from a couple datums to match a shape really well and resolve it's overall radius in cals. It would be easy here to calc volume for each slice, given already existing radius for each slice[Y].

 

[expiper]

Ackley had a slide rule and lots of common sense,,,,Roger

 

[Grimstod]

What bullet is it?

Might be in the Litz book and I can look it up for you.

Its Extra Match 7.62x54r 200gr. Same stuff the Russians used to use in the olympics before they made everyone switch to kid sized 22s

 

[Grimstod]

In the end I am trying to calculate the volume of the bullet ...

Drop it in a graduated cylinder half full of water.

This only works for bigger stuff. Very hard to measure it down to a 10th of a cc when working with small stuff.

 

[Grimstod]

Here is an example of how to find the area of a bullet with great precision. In the example the Radius of the ogive is know. I can determine almost any of the other dimensions very easily with a micrometer and calipers. The radius is the only thing thats bogging me down and preventing me from completing this.

This example is a tangent ogive.

I am mostly working off this sites info. I have emailed the author to see if he know how to determine the radius.
https://mathscinotes.wordpress.com/2011/01/12/ballistics-ogive-and-bullet-shapes-part-2/

 

[Toolbreaker]

Cast the ogive & bearing surface, then the boat tail, with Cerrosafe or no-shrink epoxy. Then measure each part of the casting with a graduated syringe. A larger syringe can be had at a vet clinic.

 

[wwbrown]

In the end I am trying to calculate the volume of the bullet ...

Drop it in a graduated cylinder half full of water.

Or do it with 10 or 100 and average it out by weight.

Pretty simple, really.

Grimstod, Read the above and do it if you want the volume of the bullet like you say.

 

[wwbrown]

Here is an example of how to find the area of a bullet with great precision. In the example the Radius of the ogive is know. I can determine almost any of the other dimensions very easily with a micrometer and calipers. The radius is the only thing thats bogging me down and preventing me from completing this.

Mathematics is capable of great precision (actually infinite with time), but I doubt very much that surplus bullets are capable of similar precision. Do you want the area or the volume?

 

[Grimstod]

Here is an example of how to find the area of a bullet with great precision. In the example the Radius of the ogive is know. I can determine almost any of the other dimensions very easily with a micrometer and calipers. The radius is the only thing thats bogging me down and preventing me from completing this.

Mathematics is capable of great precision (actually infinite with time), but I doubt very much that surplus bullets are capable of similar precision. Do you want the area or the volume?

These are pretty darn consistent. Ogive length is with in .0005ths of variance. length is almost tack on so is diameter. Every bullet I have measured with my micrometers is .3096-.3095 Even the round cavity in the base is really consistent in depth down to the .0005-+ They are almost as consistent as my berger VLDs but not quiet. Its Russian so what can you expect. I also have a few armor piercing rounds. They cost me $3 a bullet. I have taken one apart to dissect but will only be doing one since they banned there import and now they will never be available again.

To answer your question, since area is a 2dimension thing I would prefer volume.