It adds a shit ton of drag limiting range and negatively affecting accuracy. Also when firing from a long precise barrel like a tank you need a discarding sabot which is another bunch of wasted energy (used to accelerate the sabot that just disappears anyway).
A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place. Mortars are simple, cheap and lightweight - but also inaccurate and limited range. Their trajectory are also generally much steeper than artillery, and the fins help flip it the right way at apogee.
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place >Fin stabilized >why do they use fins
How else do you plan to rotate a projectile from a smoothbore barrel?
it is better to increase speed than mass. At least kinetic energy formula says so, so should be true or whatnot.
But honestly, what is the point to discuss these issues when Gayrapeans have no shells anyway, both with fins and without.
APFSDS rounds aren't spun. Theyre more effective with as little spin as possible.
"The spin from standard rifling decreases the performance of these rounds (rifling adds friction and converts some of the linear kinetic energy to rotational kinetic energy, thus decreasing the round's velocity, range and impact energy). A very high rotation on a fin-stabilized projectile can also increase aerodynamic drag, further reducing impact velocity. For these reasons APFSDS projectiles are generally fired from smoothbore guns, a practice that has been taken up for tank guns by China, India, Israel, Italy, Japan, France, Germany, Pakistan, Turkey, Russia, and the United States. Nevertheless, in the early development of APFSDS ammunition, existing rifled barrel cannons were used, (and are still in use), such as the 105 mm M68/M68E1 cannon mounted on the M60/A1/A3 main battle tank or the British 120 mm Royal Ordnance L30 of the Challenger 2 tank. To reduce the spin rate when using a rifled barrel, a "slip obturator", (slip obturation ring), is incorporated that allows the high pressure propellant gasses to seal, yet not transfer the total spin rate of the rifling into the projectile. The projectile still exits the barrel with some residual spinning, but at an acceptably low rate. In addition, some spin rate is beneficial to a fin-stabilized projectile, averaging out aerodynamic imbalances and improving accuracy. Even smooth-bore fired APFSDS projectiles incorporate fins that are slightly canted to provide some spin rate during flight; and very low twist rifled barrels have also been developed for the express purpose of firing APFSDS ammunition."
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place.
because such slender projectiles require hideous twist rates to stabilize. remember, for any given projectile density, the stabilization is a function of how long the projectile is vs. how wide it is. a 10:1 l:w projectile would not be practical to stabilize with spin.
for mortars, they are fired by dropping the round down the barrel from the muzzle
so in order for it to hit the firing pin at the bottom with enough force to trigger it, it would need to be loose, and it wouldnt engage with rifling anyways
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place.
spin-stabilization has less effect the longer and thinner an object is
but ideal penetrators are very long and very thin in order to beat armor, so rounds eventually got to a point where it was no longer feasible to rely solely on rifling
guns were also packing so much propellant, that the rifling would wear out crazy fast
so early APDS were still squat enough to benefit from rifling
but the transition to long-rods meant that they would lose accuracy quickly unless they put a driving band to counter-act the spin and rely on fins
mortars have fins because they are fired out of a smooth bore and require additional stabilization
artillery shells are spin-stabilized so do not require fins
The length to diameter ratio of a tank round means spin stabilization is detrimental to accuracy and the loss of velocity from the drag induced by the fins is much less important than having the pointiest part aligned to the target to impart maximum kinetic energy on the smallest area.
Spin vs fin stabilization.
Tanks use fins because smoothbore gives higher velocity and better pen.
Mortars use fins because you don't have to line up rifling on the shells greatly increasing rate of fire and at extremely high angles spin stabilization can enter a bi-stable state, video related.
It adds a shit ton of drag limiting range and negatively affecting accuracy. Also when firing from a long precise barrel like a tank you need a discarding sabot which is another bunch of wasted energy (used to accelerate the sabot that just disappears anyway).
A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place. Mortars are simple, cheap and lightweight - but also inaccurate and limited range. Their trajectory are also generally much steeper than artillery, and the fins help flip it the right way at apogee.
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place
>Fin stabilized
>why do they use fins
How else do you plan to rotate a projectile from a smoothbore barrel?
Put the rifling on the shell itself, I am a genius
then you'd have to use small diameter barrels that can only shoot APFSDS-type metal rods, losing the versatility of modern guns.
Okay hear me out: Two barrels
ayo
BIGGER!
increase the size of the dart and add more propellant
are you german?
So, basically go back to WW2 AP rounds? Penetration is achived by having a small diameter anon
Except when I penetrated your mother last night.
it is better to increase speed than mass. At least kinetic energy formula says so, so should be true or whatnot.
But honestly, what is the point to discuss these issues when Gayrapeans have no shells anyway, both with fins and without.
What if we increase gamma instead?
That doesn't work very well, also the AP part of APFSDS doesn't function as well with a spin stabilized projectile
APFSDS rounds aren't spun. Theyre more effective with as little spin as possible.
"The spin from standard rifling decreases the performance of these rounds (rifling adds friction and converts some of the linear kinetic energy to rotational kinetic energy, thus decreasing the round's velocity, range and impact energy). A very high rotation on a fin-stabilized projectile can also increase aerodynamic drag, further reducing impact velocity. For these reasons APFSDS projectiles are generally fired from smoothbore guns, a practice that has been taken up for tank guns by China, India, Israel, Italy, Japan, France, Germany, Pakistan, Turkey, Russia, and the United States. Nevertheless, in the early development of APFSDS ammunition, existing rifled barrel cannons were used, (and are still in use), such as the 105 mm M68/M68E1 cannon mounted on the M60/A1/A3 main battle tank or the British 120 mm Royal Ordnance L30 of the Challenger 2 tank. To reduce the spin rate when using a rifled barrel, a "slip obturator", (slip obturation ring), is incorporated that allows the high pressure propellant gasses to seal, yet not transfer the total spin rate of the rifling into the projectile. The projectile still exits the barrel with some residual spinning, but at an acceptably low rate. In addition, some spin rate is beneficial to a fin-stabilized projectile, averaging out aerodynamic imbalances and improving accuracy. Even smooth-bore fired APFSDS projectiles incorporate fins that are slightly canted to provide some spin rate during flight; and very low twist rifled barrels have also been developed for the express purpose of firing APFSDS ammunition."
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place.
because such slender projectiles require hideous twist rates to stabilize. remember, for any given projectile density, the stabilization is a function of how long the projectile is vs. how wide it is. a 10:1 l:w projectile would not be practical to stabilize with spin.
for mortars, they are fired by dropping the round down the barrel from the muzzle
so in order for it to hit the firing pin at the bottom with enough force to trigger it, it would need to be loose, and it wouldnt engage with rifling anyways
the M30 is rifled and works fine. it has an expanding obturator skirt.
>A better question is why APFSDS tank rounds and most mortars use fin stabilization in the first place.
spin-stabilization has less effect the longer and thinner an object is
but ideal penetrators are very long and very thin in order to beat armor, so rounds eventually got to a point where it was no longer feasible to rely solely on rifling
guns were also packing so much propellant, that the rifling would wear out crazy fast
so early APDS were still squat enough to benefit from rifling
but the transition to long-rods meant that they would lose accuracy quickly unless they put a driving band to counter-act the spin and rely on fins
One of these things is rifled.
Its not the tank barrel or the mortar.
Velocity, required precision, and flightpath.
mortars have fins because they are fired out of a smooth bore and require additional stabilization
artillery shells are spin-stabilized so do not require fins
There are shells that do.
The length to diameter ratio of a tank round means spin stabilization is detrimental to accuracy and the loss of velocity from the drag induced by the fins is much less important than having the pointiest part aligned to the target to impart maximum kinetic energy on the smallest area.
Spin vs fin stabilization.
Tanks use fins because smoothbore gives higher velocity and better pen.
Mortars use fins because you don't have to line up rifling on the shells greatly increasing rate of fire and at extremely high angles spin stabilization can enter a bi-stable state, video related.
Interesting, Thanks anon.
>Why do mortar rounds have fins
Not all of them, only smoothbore
You know what they say. Smoothbore, smoothbrain.
Spin stabilisation vs fin stabilisation
because artillery guns are rifled
Because mortar and tank rounds are fish, while artillery shells are mammals.
mammals can have fins, look at whales
iirc most arty guns are rifled whereas mortars and tank guns are generally smoothbore