How about we make a bullet shaped roughly like this, fire it

>Due to the more aerodynamic shape than that which is found in normal bullets this bullet would have better long range capabilities.

No. The added mass would counteract the benefits of being more aerodynamic. This would also fill up much more of casing reducing even further the amount of gunpowder.

>>33216946
>added mass
Where'd you get that from? The weight of the bullet was not mentioned in the post.
>reducing even further the amount of gunpowder
The size of the casings wasn't mentioned in the post either.

>>33217012
Are you retarded? Do you know how bullets are fired? Do you know that bigger = more mass (usually)?

>>33217012
>The size of the casings wasn't mentioned in the post either.
Doesn't matter if the case is .22lr or .50BMG. A football shaped projectile is always going to take up more room in a case than a traditional projectile.

>>33216946
Not OP, but you sound pretty fucking dumb.

If you cut off a bit of the trailing tail, you have a typical boat tail rifle bullet.

>>33216915

Brilliant idea! Since it also vaguely resembles a boat, let's call it a "boat tail" bullet too!

>>33217112
Nowhere has the density of the material that makes up the bullet been mentioned, why do you presume that there is only one material bullets can be made out of?
>>33217123
And? You claimed that this bullet shape would reduce powder load and i just said that the casing size wasn't mentioned.

>>33216915
The base shape of a bullet has a pretty large effect on pressure and velocity. With a shape like op's, both would be reduced.

Once you got it moving, it would have less axial drag, so it would retain velocity better. However the transverse area is probably larger than a bt bullet of the same weight/caliber, so it would be more effected by wind drift.

At least in my opinion. I'm only a mechanical engineer, but have dealt with ballistics quite a bit.

>>33216915
Without being stabilized by rotational inertia the slightest crosswind would make it tumble.

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>>33217183
This

>>33217194
lol

>>33217183
>>33217194
This is untrue on many fronts.

The shape i proposed has a higher length/width ratio than is practical for normal rifling stabilized rounds.

Also, usual boat tail bullets aren't even close to the LD-Haack, or Von Karman as it is commonly called, nose cone design.

>>33216915

How about I fuck your mother instead?

>>33217202
How come?
>>33217201
Yes, i see crosswinds being a major problem for accuracy of this shape.

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A basic search would tell you why bullets aren't made like your image.

Namely termial ballistics and what happens to propellant behind an aerofoil-like tail design. It would be worse.

>>33217198
I claimed nothing, that was my first post in-thread.

And yes. Having a football shaped bullet will reduce powder charge compared to a traditional bullet, no matter what case. Unless you don't load it to the widest point, in which case I'd imagine it'd be a motherfucker to design a way to feed it.

>>33217237
Because the bullet shape has been optimized for minimal air resistance assuming that the airflow is going to be precisely parallel to the radial symmetry axis.

Any deviation in the airflow vector is going to cause cavitation on the opposite side of the bullet- which is a problem for all non-spherical projectiles, but normally it's mitigated with either gyroscopic or fin stablization.

>>33217270
>This would also fill up much more of casing reducing even further the amount of gunpowder.
Is this not a claim?

The first part is true, this bullet design would indeed take up more space from inside the casing. The second part however is not true since the size of the cartridge was not specified anywhere.

>>33217287
Not op, that's interesting. So just make it spin then?

>>33217364
Yes, it's a claim.
I however, am not that poster.

>>33217364
This. It doesn't matter if the bullet takes up more space, you can just make a longer cartridge if you need more powah. OP, however, is bad at saying that

>>33217368
Yes, make it spin.

Getting it to engage the rifling effectively might be a challenge on that shape, though. The flatter the edges, the closer the performance would be to a monolithic FMJBT.

>>33217287
Why can't it be mitigated by just having the center of mass forwards of the symmetry axis?

Isn't this how all fin stabilized projectiles work? By adding shapes to the rear of the projectile you are moving the symmetry axis backwards. So why not move the center of mass forwards while maintaining the symmetry axis in place?

>>33216915
> fire it out of a smoothbore barrel, and stabilize it by having the center of gravity forwards of the symmetry axis of the bullet.
A forward Centre of mass means that it will tumble almost immediately, darts are biased forwards as the fins apply more drag than the head mass.

>Due to the more aerodynamic shape than that which is found in normal bullets this bullet would have better long range capabilities.
Due to the shape any force applied to the bullet are acting on surfaces over 60 degrees from the direction of travel, this is a mechanical loss of energy that would cripple the velocity. the flat on the back of the bullet exists to give a good acting surface

If you cannot see this try this.
You need to push a car
Do you
A. go behind the car and push on somewhere you can rest your hands
B, go to the car door and try push your hands along the car's sides

>>33217572
>good acting surface

Is that actually an issue when you're riding an explosion in an enclosed space?

>>33217613
Yes, Any lost mechanical force like the results in more energy transfer to the barrel as heat and barrel being stretched by the force that should be acting primarily on the bullet

>>33216915
How do you feel about Glider Infantry?

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>>33217572
>will tumble almost immediately
Look at this picture, the shape on the left will correct itself so that it is parallel to the airflow, the shape in the middle will not move because there is as much area behind and in front of the center of mass, the shape on the right is the same as the shape on the left and will also eventually orient itself parallel to the airflow.

There exists a gas seal inside the barrel of a firearm, therefore your example does not apply.

>>33217632
I'll take your word on it.

>>33217519
There are several reasons this shape never took off for man portable firearms. First is cartridge size the base of the projectile would infringe on the section of the case reserved for powder and expansion. The reloaders that ever tried heavy 30-06 intended bullets in 308s know where that goes. So right from the get go you have a need for speciality wildcat cartridge. Now if that is not a problem one has to deal with chamber pressures. To get the most of this will likely require some reinforcement so mauser or ruger #1 may be what one is looking for. I am not sure how stable the bullet will be in terms of being able to wiggle so I would hesitate on magazine feeding. Finally the barrel...... I do not know enough to tell you what twist or length will support your monstrosity and that is before considering what bullet weight and construction will entail. Could you do it sure would it work maybe will it be cost effective not a chance in hell

>>33217678
> the shape in the middle will not move because there is as much area behind and in front of the center of mass
Far too simplistic a view of the issue, there are more forces acting upon the bullet, the second you have misalignment you are creating vortex patterns which also act on the bullet.

As for the forward COM bullet idea, i'll try get you to engage your thought processes yourself

If a Bullet with a forwards CoM was inherently stable, why would darts, sabot rounds and rockets in general need fins to create drag to correct them?

>There exists a gas seal inside the barrel of a firearm, therefore your example does not apply.

There exists a temporary gas seal that degrades over usage
The powder in a cartidge is a finite energy and it has a specific expansion rate
If the bullet has not been accelerated to optimal speeds at the rate of expansion more of the energy is lost as heat into the barrel.
The reason for this is any energy not used by the projectile is acting outwards on the barrel and the barrel acting in compression.

metal is elastic to within certain tolerances, if the force exerted on the barrel exceeds this tolerance then the barrel is deformed and swaiged wider by the round
Repeated instances of this will reduce the gas sealing effect, which then causes the fall of in velocity to be far more drastic

>>33217983
>If a Bullet with a forwards CoM was inherently stable, why would darts, sabot rounds and rockets in general need fins to create drag to correct them?
The thing is that darts, sabot rounds, and rockets do not have a forwards CoM and therefore they use fins to move the symmetry axis backwards so that the symmetry axis is behind the center of mass.

OP based on your responses you are a genius/expert engineer and therefore do not need the input of us mere mortals. I suggest you get to manufacturing prototypes of these puppies and change the world of firearms forever.

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The amount of bullshit in this thread is astonishing

>>33216915
You'd need a sabot to get it out of the barrel straight. And the c.g. would need to be very far forward so that the moment arm between c.g. and a.c. is long enough to provide sufficient self stabilization. For comparison look at the big fins of tank ammo.

>>33217112

>Different shape=bigger

Take off your helmet, little stevie. Its time to take your medicine and have nap time.

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>>33216915
So basically a Sears-Haack boolit?
https://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body
The terminal ballistics would probably be pretty lousy, but you're right that it would have excellent external ballistics.

One question though, why smoothbore?

>>33216946
>The added mass would counteract the benefits of being more aerodynamic.
Two things:
1. Mass and sectional density can be a GOOD thing, and
2. OP said the CG should be forward, so the tail would in all likelihood be hollow. It wouldn't necessarily be significantly heavier than a Spitzer bullet of the same caliber.
>This would also fill up much more of casing reducing even further the amount of gunpowder.
True. This would be best-suited to shouldered cartridges which have large case volume already.
>>33217183
Also this. Though OP's cigar would have even better pressure recovery and even less drag.

>>33217244
>what happens to propellant behind an aerofoil-like tail design.
Care to elaborate?

>>33217572
>A forward Centre of mass means that it will tumble almost immediately
You've got that backwards. It's tail-heavy bullets which upset more readily. Hence why 5.45x39 has a hollow nose (despite not actually being hollow-point).
>>33217678
Nice grafic m8

So yeah... I kinda like OP's idea, even if it's only useful for competitive benchrest shooting.

>>33217123
This guy is right, unfortunately.
I would ms paint proof if I were on my computer.
My knowledge of fluid dynamics isnt great enough to determine whether the new shape would offer aerodynamic advantage, though.

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>>33217983
>If a Bullet with a forwards CoM was inherently stable, why would darts, sabot rounds and rockets in general need fins to create drag to correct them?
For the latter two, it's because their CG isn't substantially forward of center. For the latter, it's because hand-thrown darts don't go that fast and so there's not much aerodynamic pressure to stabilize them before they reach the dartboard - hence both FOC CG *and* large fins are required to get the job done.

Without rifling, realistically OP's projectile would still require fins. The CG would have to be VERY FOC to do without them, meaning most of the bullet (except the nose) would have to be hollow or polymer-filled (making for a very light, low-BC bullet). But in principle it is possible.

But with spin-stabilization, OP might not need fins.

>>33218485
>My knowledge of fluid dynamics isnt great enough to determine whether the new shape would offer aerodynamic advantage, though.
It would, ceteris paribus.
http://docs.desktop.aero/appliedaero/compress3d/SearsHaack.html
Also the longer the better, but there are of course practical limits to fineness when designing a firearm projectile.

>>33218409
There is a straight walled portion in the picture, therefore a sabot is not necessary.

>i've got this idea for something that I just thought of in a few minutes to replace something that has been worked on and improved for centuries

/k/

>>33218773
There is a reason i said "How about" and not "ive got this revolutionary idea" ,this thread was borne of my own curiosity on the subject.

I wished to know why these kind of bullets aren't used, not broadcast that i've got a new bullet design because that is indeed not the case.

>>33217198
>the casing size wasn't mentioned.
Are you really this dense?
The casing size doesn't matter a football shaped projectile will always take up more casing space than a traditional bullet regardless of the fucking casing size.

>>33218925
The shape does take more space from the casing ,yes, but since the casing size wasn't mentioned that doesn't necessarily lead to less gunpowder.

>>33216915

The practical reality is you have to have a flat surface in the back for expanding gas to push on. If it is a true sear-haack, the gas will expand past the back pointy end further, reaching the middle of the bullet and expanding hard at the case, chamber, barrel, etc. For the same reason a pistol bullet (short, fat, heavy) is so much more efficient than a rifle round, this would be even less efficient. And contribute to grenading your gun.

>>33217217

Hey, Aluminum-Haack-anon. I remember you from yesterday. Your bullet is still too long to spin stabilize.

Just start loading those VLD projectiles like we discussed.

>>33219027
>Your bullet is still too long to spin stabilize.
Why is it that longer bullets require more twist?
Is it because their principal moments are different? An inertia coupling kind of thing?
Is it because the longer profile has higher aerodynamic moments?
Is it just because longer bullets are more massive and have lower muzzle velocities, and thus require more twist to reach the same RPM?

>>33219097

The actual gyroscopic physics equations are beyond my ken.

Limitations on rifling, poor gyroscopic inertia when diameter is small compared to length and increased movement arm relative to screwball center of mass moving back towards the rear of the bullet for VLD designs are top hits in google results.

Good luck, fingers crossed you come up with something cool.

>>33218980
>he practical reality is you have to have a flat surface in the back for expanding gas to push on.
>I don't know what a driving band is

>>33220291
>Ancient Greek lead sling bullets with a winged thunderbolt engraved on one side and the inscription "DEBNTS" on the other side, 4th century BC, from Athens, British Museum.

>>33220303
Not that guy but a driving band wouldn't make much difference. The whole point is that with a sear-haack, there would be a significant pressure loss, and inefficient "piston" shape (bullets are essentially pistons) that would reduce velocities and possibly be dangerous. Adding a driving band doesn't mitigate that, and would only serve to increase drag on the projectile.

Bump so it doesn't die

>>33216915
>Due to the more aerodynamic shape than that which is found in normal bullets this bullet would have better long range capabilities.

Fine for target shooting, but inherently stable bullets don't have good terminal performance. Most projectiles rely upon either being inherently unstable once they lose speed (thus tumbling and possibly fragmenting), or expansion to cause tissue damage. Neither of these are really possible for a projectile that's inherently stable. This is one of many reasons why we don't typically use fin-stabilized sabot rounds for small arms.