Re: Army experiments with new bullet jacket design
04/01/09
04/01/09
Re: Army experiments with new bullet jacket design
i came up w/ that idea when my engineer brother was telling me how they were starting to dimple the back of cruise ships to save gas money....too bad it isn't true..(the bullet thing, the cruise ship thing is real)
i came up w/ that idea when my engineer brother was telling me how they were starting to dimple the back of cruise ships to save gas money....too bad it isn't true..(the bullet thing, the cruise ship thing is real)
Re: Army experiments with new bullet jacket design
LOL i have been toying with this idea for a lot longer then they have. This type of design is not new and it should work well but has its flaws. Its tough to work this into a current bullet because of the cost and the fact that a bullet has to spin when its in flight to create stability. I wish you good luck because you will need it trust me.....
LOL i have been toying with this idea for a lot longer then they have. This type of design is not new and it should work well but has its flaws. Its tough to work this into a current bullet because of the cost and the fact that a bullet has to spin when its in flight to create stability. I wish you good luck because you will need it trust me.....
Re: Army experiments with new bullet jacket design
Good article.
Good article.
Re: Army experiments with new bullet jacket design
NotAGuru, golf balls also spin while they fly through the air. When you compared actual angular velocities, they are spinning at almost the same rate.
NotAGuru, golf balls also spin while they fly through the air. When you compared actual angular velocities, they are spinning at almost the same rate.
Re: Army experiments with new bullet jacket design
Your telling me they "spin" the same?
Your telling me they "spin" the same?
Re: Army experiments with new bullet jacket design
would be nice if it works... Shoot match VLD's for game and still get the expansion.
would be nice if it works... Shoot match VLD's for game and still get the expansion.
Re: Army experiments with new bullet jacket design
I wonder how that design would work on a race car?
I wonder how that design would work on a race car?
Re: Army experiments with new bullet jacket design
LOL! I love the picture of the "advanced Doppler Radar"...having worked with that equipment in the Army I can safely say it has absolutely nothing to do with radar or is even close to it...pretty convincing to the untrained eye, however
LOL! I love the picture of the "advanced Doppler Radar"...having worked with that equipment in the Army I can safely say it has absolutely nothing to do with radar or is even close to it...pretty convincing to the untrained eye, however
Re: Army experiments with new bullet jacket design
This must be why all advanced fighter aircraft have "dimpled" radomes.
The idea is not completely stupid, but it is ranking high on the dumb scale.
I liked the comment about the "dual radius" nose which was excluded from the running (Try about twelve radii before optimal nose forms can be approximated, I use twenty-two). These people do not understand anything about supersonic flight, or laminar flow. The irony is that this level of ignorance exists within an environment enjoying the kind of R&D funding available to the "developers".
It is maddening.
This must be why all advanced fighter aircraft have "dimpled" radomes.
The idea is not completely stupid, but it is ranking high on the dumb scale.
I liked the comment about the "dual radius" nose which was excluded from the running (Try about twelve radii before optimal nose forms can be approximated, I use twenty-two). These people do not understand anything about supersonic flight, or laminar flow. The irony is that this level of ignorance exists within an environment enjoying the kind of R&D funding available to the "developers".
It is maddening.
Re: Army experiments with new bullet jacket design
Calm down Noel,
It's not maddening, it's a joke.
April fools.
On the subject of optimal nose design, that's a highly velocity dependent geometry. In other words, the nose (ogive) that's <span style="font-style: italic">optimal</span> for Mach 2.5 is different than the shape that's <span style="font-style: italic">optimal</span> for Mach 2.0, and that's different than the <span style="font-style: italic">optimal</span> shape for Mach 1.5, etc. If the designer knew the exact velocity range that the projectile would always fly between (3000 fps to 1800 fps for example), an ogive shape could be designed that was optimal for that velocity range. However, the reality is that bullets will experience a range of different flight speeds. This makes the idea of a <span style="font-style: italic">one and only 'optimal'</span> nose profile impossible.
A constant radius secant ogive with a radius equal to twice the radius of a tangent ogive is a practical minimum drag shape for a wide range of supersonic flight speeds. For subsonic flight, a tangent ogive has less drag than a secant.
Boat tail angle and length shares the same velocity dependence.
I'm not trying to pull your chain, just didn't want anyone to go away with the idea that the government if actually funding a dimpled bullet project. At least in this case, thankfully, the madness is a farse.
Take care,
-Bryan
Calm down Noel,
It's not maddening, it's a joke.
April fools.
On the subject of optimal nose design, that's a highly velocity dependent geometry. In other words, the nose (ogive) that's <span style="font-style: italic">optimal</span> for Mach 2.5 is different than the shape that's <span style="font-style: italic">optimal</span> for Mach 2.0, and that's different than the <span style="font-style: italic">optimal</span> shape for Mach 1.5, etc. If the designer knew the exact velocity range that the projectile would always fly between (3000 fps to 1800 fps for example), an ogive shape could be designed that was optimal for that velocity range. However, the reality is that bullets will experience a range of different flight speeds. This makes the idea of a <span style="font-style: italic">one and only 'optimal'</span> nose profile impossible.
A constant radius secant ogive with a radius equal to twice the radius of a tangent ogive is a practical minimum drag shape for a wide range of supersonic flight speeds. For subsonic flight, a tangent ogive has less drag than a secant.
Boat tail angle and length shares the same velocity dependence.
I'm not trying to pull your chain, just didn't want anyone to go away with the idea that the government if actually funding a dimpled bullet project. At least in this case, thankfully, the madness is a farse.
Take care,
-Bryan
Re: Army experiments with new bullet jacket design
Bryan,
Thanks for the clarification Bryan, I guess I have an underdeveloped sense of humor.
I understand that "optimal" nose shape is velocity dependent. I also agree that there is an optimal nose shape for a given "velocity range". Where I think we are diverging is in the assumption that bullets "will experience a range of different flight speeds". I am working from precisely the opposite premise, at least as it applies to my work.
What is "practical", is something quite different than what is "optimal". A "constant radius secant ogive" is never optimal... in any specific velocity, or speed range.
Ditto for the boat-tail. A "specific (planar) angle" is never optimal, but it is practical... especially where manufacturing methods do not permit the type of shapes, and tolerances necessary to even mitigate in-bore cant.
Best,
(a calmer, and less maddened)... Noel
Bryan,
Thanks for the clarification Bryan, I guess I have an underdeveloped sense of humor.
I understand that "optimal" nose shape is velocity dependent. I also agree that there is an optimal nose shape for a given "velocity range". Where I think we are diverging is in the assumption that bullets "will experience a range of different flight speeds". I am working from precisely the opposite premise, at least as it applies to my work.
What is "practical", is something quite different than what is "optimal". A "constant radius secant ogive" is never optimal... in any specific velocity, or speed range.
Ditto for the boat-tail. A "specific (planar) angle" is never optimal, but it is practical... especially where manufacturing methods do not permit the type of shapes, and tolerances necessary to even mitigate in-bore cant.
Best,
(a calmer, and less maddened)... Noel
Re: Army experiments with new bullet jacket design
Noel,
Thanks for your reply. On re-reading my post, it sounded a bit more abrasive than I meant to be; this sometimes happens with posts like this, but thanks for not taking it badly.
I gather from your statements about minimum drag that you have a specific speed range in mind for which your designs are optimized, and that's certainly reasonable.
As for minimal drag nose shapes, I paraphrase from Bob McCoy:
<span style="font-style: italic">"The optimum secant ogive nose shape Rt/R = 0.5, with a small meplat or inscribed hemispherical nose tip, gives slightly more drag than the optimum nose shapes illustrated in Figure 4.47 [includes: cone, 3/4 power law, Sears-Haak, and parabaloid]. For all practical purposes, there is no significant difference, and both the secant ogive and the 3/4 power-law shapes may be considered to be practical minimum drag nose shapes at supersonic speeds."</span>
Of course if you're making projectiles on a CNC lathe, it's just as easy to program it with a slightly more optimal shape, even if the difference isn't very much.
The boat tail is a tricky one. I understand how a slight advantage is possible from blending the bearing surface into the boat tail instead of an abrupt junction, but I wouldn't let the slope of the boat tail ever get beyond 8-10 degrees. The flow will still separate if the angle becomes too steep. What's worse, on a curved boat tail, the flow separation will not be well defined and could cause dynamic stability problems at certain flight speeds. I can't remember how steep the boat tails get on your projectiles (been a while since I've seen the pics), but this is something that turned projectiles often go overboard with (meaning, the slope of the boat tail often gets too steep). It's better for dynamic stability to have a clean sharp base on the bullet for the flow to separate from instead of a long curved heal.
I'm fostering a growing interest in larger calibers and extended range shooting. I'll be very interested to give your projectiles a go at some point in the future. Can you please point me to some information on your bullets? I remember seeing something about them on here a while ago, is there a website? I'm having a 338 Edge built with a gain twist (1:10 to 1:9) Bartlien, I hope that's fast enough to stabilize your bullets.
Take care,
-Bryan
Noel,
Thanks for your reply. On re-reading my post, it sounded a bit more abrasive than I meant to be; this sometimes happens with posts like this, but thanks for not taking it badly.
I gather from your statements about minimum drag that you have a specific speed range in mind for which your designs are optimized, and that's certainly reasonable.
As for minimal drag nose shapes, I paraphrase from Bob McCoy:
<span style="font-style: italic">"The optimum secant ogive nose shape Rt/R = 0.5, with a small meplat or inscribed hemispherical nose tip, gives slightly more drag than the optimum nose shapes illustrated in Figure 4.47 [includes: cone, 3/4 power law, Sears-Haak, and parabaloid]. For all practical purposes, there is no significant difference, and both the secant ogive and the 3/4 power-law shapes may be considered to be practical minimum drag nose shapes at supersonic speeds."</span>
Of course if you're making projectiles on a CNC lathe, it's just as easy to program it with a slightly more optimal shape, even if the difference isn't very much.
The boat tail is a tricky one. I understand how a slight advantage is possible from blending the bearing surface into the boat tail instead of an abrupt junction, but I wouldn't let the slope of the boat tail ever get beyond 8-10 degrees. The flow will still separate if the angle becomes too steep. What's worse, on a curved boat tail, the flow separation will not be well defined and could cause dynamic stability problems at certain flight speeds. I can't remember how steep the boat tails get on your projectiles (been a while since I've seen the pics), but this is something that turned projectiles often go overboard with (meaning, the slope of the boat tail often gets too steep). It's better for dynamic stability to have a clean sharp base on the bullet for the flow to separate from instead of a long curved heal.
I'm fostering a growing interest in larger calibers and extended range shooting. I'll be very interested to give your projectiles a go at some point in the future. Can you please point me to some information on your bullets? I remember seeing something about them on here a while ago, is there a website? I'm having a 338 Edge built with a gain twist (1:10 to 1:9) Bartlien, I hope that's fast enough to stabilize your bullets.
Take care,
-Bryan
Re: Army experiments with new bullet jacket design
Bryan,
There was no offense taken by your language... I did over-react to a joke. Occasionally I am just slow at picking up on humor.
I was unaware of McCoy's statement, and I agree with it for the most part. For what it is worth, a simple secant radius ogive can be more efficient than a number of the more complex, volumetrically equal, nose geometries which he named within the velocity ranges possible in small arms. I am looking at no more than a 5% gain over a secant ogive equivalent.
Tail design is where most of the interesting stuff is being discovered, and it happens within an eight degree recurve angle (as roughly averaged from shaft to tail-termination). The primary gains are in high-velocity stability, and low-velocity efficiency. Much of this was learned only recently. While I do agree with the "clean sharp base" standard, it turns out that even this feature can be improved upon. It is not as simple as I thought.
If your employer will allow you to sign an NDA, I would be happy to share more information... and get you set-up with the right barrel for your project.
Best,
Noel
Bryan,
There was no offense taken by your language... I did over-react to a joke. Occasionally I am just slow at picking up on humor.
I was unaware of McCoy's statement, and I agree with it for the most part. For what it is worth, a simple secant radius ogive can be more efficient than a number of the more complex, volumetrically equal, nose geometries which he named within the velocity ranges possible in small arms. I am looking at no more than a 5% gain over a secant ogive equivalent.
Tail design is where most of the interesting stuff is being discovered, and it happens within an eight degree recurve angle (as roughly averaged from shaft to tail-termination). The primary gains are in high-velocity stability, and low-velocity efficiency. Much of this was learned only recently. While I do agree with the "clean sharp base" standard, it turns out that even this feature can be improved upon. It is not as simple as I thought.
If your employer will allow you to sign an NDA, I would be happy to share more information... and get you set-up with the right barrel for your project.
Best,
Noel
Re: Army experiments with new bullet jacket design
This is a joke? Not funny.
This is a joke? Not funny.
Re: Army experiments with new bullet jacket design
It was POSTED ONE friggin APRIL. jeez ...
It was POSTED ONE friggin APRIL. jeez ...
Re: Army experiments with new bullet jacket design
Yes Will,
But it was a very polished post!
-Noel
Yes Will,
But it was a very polished post!
-Noel
Re: Army experiments with new bullet jacket design
Yessir, I have to agree it was well done, almost as well done as the post about Kalifornicate (aka Left Coast) having "Air stations" for air rifles and a $95 refill license. However, at this time there are no state authorized stations. I wouldn't put it past them but ... look at what else was written !!!
Yessir, I have to agree it was well done, almost as well done as the post about Kalifornicate (aka Left Coast) having "Air stations" for air rifles and a $95 refill license. However, at this time there are no state authorized stations. I wouldn't put it past them but ... look at what else was written !!!
Re: Army experiments with new bullet jacket design
... guess I have become jaded in the extent to which government organizations (even the military) can be expected to indulge idiocy.
And the situation does not appear to be improving with time.
... guess I have become jaded in the extent to which government organizations (even the military) can be expected to indulge idiocy.
And the situation does not appear to be improving with time.
Re: Army experiments with new bullet jacket design
The part that most appeared to be close to actually viable , was the reference to a non-lead core , of some exotic metal , I remember a couple of bullet makers experimenting with heavier than lead metal , ie Tungsten , and saying they where getting very good long range results
The part that most appeared to be close to actually viable , was the reference to a non-lead core , of some exotic metal , I remember a couple of bullet makers experimenting with heavier than lead metal , ie Tungsten , and saying they where getting very good long range results
Re: Army experiments with new bullet jacket design
Chris,
The chances are that you read about a tungsten/polymer composite projectile. Non-saboted tungsten is much too dense, although armor defeating cartridges were developed by both the British, and the Germans, during WWII based on this idea. Barrel life was less than spectacular, and there are more practical ways to elevate sectional density... unless the objective is strictly penetration, in which case tungsten is still not the best choice of material.
The specific gravity of lead can be matched exactly with a non-toxic polymer-blend. It is my understand that "green" bullets have already been produced with tungsten in a Torlon matrix.
Chris,
The chances are that you read about a tungsten/polymer composite projectile. Non-saboted tungsten is much too dense, although armor defeating cartridges were developed by both the British, and the Germans, during WWII based on this idea. Barrel life was less than spectacular, and there are more practical ways to elevate sectional density... unless the objective is strictly penetration, in which case tungsten is still not the best choice of material.
The specific gravity of lead can be matched exactly with a non-toxic polymer-blend. It is my understand that "green" bullets have already been produced with tungsten in a Torlon matrix.
