Jump to content
Sturgeon's House

Nose Ogive Volume Formula searched


Impulse
 Share

Recommended Posts

I found a formula on a Parabolic Nosecone -> V= Pi * d² * h : 8   (and additionally :1000 for mm³ in cm³ for g/cm³ calculation)

The descripion notes that diffrent shapes of parabolic nosecones exist.

The question is , for what version is the given formula?

Quote: " K' = 0 for a cone , K' = 0.5 for a 1/2 parabola , K' = 0.75 for a 3/4 parabola , K' = 1 for a full parabola , For the case of the full Parabola (K'=1) the shape is tangent to the body at its base, and the base is on the axis of the parabola. Values of K' less than one result in a slimmer shape, whose appearance is similar to that of the secant ogive. The shape is no longer tangent at the base, and the base is parallel to, but offset from, the axis of the parabola."

= is the given formula for a Tangent Ogive/ or another shape? + Is the "tangent" a true Tangent Ogive or just as quoted "tangent at its base"

The reason for this question is that the formula results in a rather small volume, so a diffrent shape seems possible, (because a diffrent angle towards the base where the diameter is the largest, would result in high volume loss).

 

+ does anyone knows the formula for a truly tangent nosecone?

Thanks for any answers.

Link to comment
Share on other sites

Hello,

 

I'm not sure which nosecone variety your formula corresponds to, it doesn't look like any that I am familiar with (although it might just be in a different form).

 

Here is the formula for a tangent ogive (via wiki);

 

Nose_cone_tangent_ogive.png

uVctndo.png

3V3GqqW.png

 

This site also has a discussion; http://tmtpages.com/tech/tangent_ogive.htm

Unless you make the ogive cover the whole semicircle, there will be a discontinuity in the curve at the nose (a point), is this what you meant by a true tangent ogive.

 

For whatever reason, most of the results when you google "tangent ogive" relate to bullet design, surprisingly few about rocketry or aircraft. Then again, most rockets probably use Sears-Haack bodies, which have less drag but are more complex to construct.

 

Finally, welcome to SH. :)

Link to comment
Share on other sites

@LostCosmonaut

Ive read the site a few days ago, and calculated p a few weeks ago. Whats y for?

A formula for V is hard to find i quess, but i have an idea. I tought about measuring my drawing, but its ofcourse too tiny, so i scale it up and draw it on quad paper with a string. Then slice the Ogive to dozends of cylinders and calcualte theyr volume.  :wacko: Thats gonna be a lot of math.

Thanks everyone for taking a look and the answers. Great site, just donated 20$

I commonly have my pc running over the day, so i propably now always have the site open.

Im always open for conversations, basicly on any topics. While my main points of interest are in Military Smallarms and Ammunition. Eighter you use this as open thread/ make a group/ or write me if its superduper secret :ph34r: like that the .300blk actually isnt that great, or rare secrets like that 5.56x45 actually does (much) more than ".22cal holes". Thanks!

Link to comment
Share on other sites

@LostCosmonaut

Ive read the site a few days ago, and calculated p a few weeks ago. Whats y for?

A formula for V is hard to find i quess, but i have an idea. I tought about measuring my drawing, but its ofcourse too tiny, so i scale it up and draw it on quad paper with a string. Then slice the Ogive to dozends of cylinders and calcualte theyr volume.  :wacko: Thats gonna be a lot of math.

Thanks everyone for taking a look and the answers. Great site, just donated 20$

I commonly have my pc running over the day, so i propably now always have the site open.

Im always open for conversations, basicly on any topics. While my main points of interest are in Military Smallarms and Ammunition. Eighter you use this as open thread/ make a group/ or write me if its superduper secret :ph34r: like that the .300blk actually isnt that great, or rare secrets like that 5.56x45 actually does (much) more than ".22cal holes". Thanks!

 

y is the distance from the centerline of the ogive to the outside (given by that formula). Basically, it's the radius of your ogive at any given point along it.

 

For calculating the volume of it, I'd recommend learning calculus (hard and long), finding somebody who knows calc (probably shorter and easier), or using something like Wolfram Alpha; https://www.wolframalpha.com/

 

Here's that site calculating the volume of a parabolic nose cone with length 4, radius .75, and K = 1; https://www.wolframalpha.com/input/?i=volume+of+revolved+solid+.75*(2*(x%2F4)-(x%2F4)%5E2)+from+0+to+4

Link to comment
Share on other sites

I did read almost everything of him on TFB. Im like 40times a day on there. Also did read everything on 196800rpm. Still thanks for recommending it in case.


___NEW Topic:  about Barrels->  whats the minimum wall thickness thats save for a chamber (55000psi). + what would be the smallest that even would hold up. And whats the wall thickness you would use on an automatic Rifle (not for the "automatic rifleman", just for a rifle that can technically shoot fullauto).

Link to comment
Share on other sites

___NEW Topic:  about Barrels->  whats the minimum wall thickness thats save for a chamber (55000psi). + what would be the smallest that even would hold up. And whats the wall thickness you would use on an automatic Rifle (not for the "automatic rifleman", just for a rifle that can technically shoot fullauto).

 

Look up something called "hoop stress."  The minimum necessary barrel thickness will be a function of the cross sectional area of the cartridge, the peak pressure of the cartridge, and the tensile yield strength of the steel times whatever safety factor.

Link to comment
Share on other sites

Thanks. Did just read the definition of Hoop Stress, etc, known the physic behind it but not the math. Now found this calculator http://www.engineeringtoolbox.com/stress-thick-walled-tube-d_949.html, there seem to be no savety factor notes. Also theyr always called "calculation for thin/thick walled cylinder". Which one should i use thin/ or thick?

Chamber: 55000psi , 10mm case diameter, 22mm Chamber diameter (6mm walls).

Used data: 55000psi  ; 14,69594878psi as standart atmospheric pressure  ;  0,19685" inside radius  ; 0,433071" outside radius  ;  0,314961" radius to the middle of the wall.

Axial Stress: 14304
Hoop: 41376
Radial Stress: -12767,5

Does the results make sence? Is it safe/or unsafe with verry high quality steel? How to include savety factor.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...