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Eipi10 wrote: I like how GW gave some thought to the redemptor to make it look like a thing that can actually walk, I just wish they would do the same for their guns. Sometimes I wonder if whoever designed the bolter had ever looked at a gun in real life. I guess on a tiny plastic model your mind fills in all the details to make it plausible, that doesn't work on these detailed 3D models.
At least the ejection port actually lines up with the barrel.
Meanwhile the Palanite Enforcers get a sniper rifle (bottom middle) where the bolt wouldn't be able to move backwards without the bolt handle immediately hitting the receiver frame...
That hurts me. It might even be worse than Azrael’s bullpup combibolter.
Waiting for my shill money from Spiral Arm Studios
The bolt action sniper rifle is even dumber because IT STILL HAS A SELF-LOADING GAS SYSTEM!(that second tube attached to the bottom of the barrel)
So clearly the bolt handle is only necessary to manually clear jams. But it's obstructed so nothing on it will work...
This message was edited 2 times. Last update was at 2020/01/22 16:48:57
Self-proclaimed evil Cat-person. Dues Ex Felines
Cato Sicarius, after force feeding Captain Ventris a copy of the Codex Astartes for having the audacity to play Deathwatch, chokes to death on his own D-baggery after finding Calgar assembling his new Eldar army.
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
This message was edited 3 times. Last update was at 2020/01/22 16:58:37
Guardsmen, hear me! Cadia may lie in ruin, but her proud people do not! For each brother and sister who gave their lives to Him as martyrs, we will reap a vengeance fiftyfold! Cadia may be no more, but will never be forgotten; our foes shall tremble in fear at the name, for their doom shall come from the barrels of Cadian guns, fired by Cadian hands! Forward, for vengeance and retribution, in His name and the names of our fallen comrades!
Waiting for my shill money from Spiral Arm Studios
Yeah, frisbees are a terrible projectile choice. They'd be better off shooting small BBs at high velocity. At least a round ball is somewhat stable in flight. Not as good as a cone, but you'd have some range, accuracy, and more mass.
Self-proclaimed evil Cat-person. Dues Ex Felines
Cato Sicarius, after force feeding Captain Ventris a copy of the Codex Astartes for having the audacity to play Deathwatch, chokes to death on his own D-baggery after finding Calgar assembling his new Eldar army.
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Citation is 3e Eldar Codex.
Frisbees turn in flight because the relative air velocity over one side of it is different than the relative velocity over the other side. One side experiences a faster airflow, and therefore generates more lift and more drag than the other side. They will always do this, it's a fact of aerodynamics.
Spinning rifle bullets do not experience this because the axis of rotation is parallel to the direction of travel.
As for a molecule thick frisbee, it will experience drag from skin friction & the boundary layer which doesn't care how thick it is [only it's surface area], and it will experience shockwave drag which is theoretically affected by how thick it is [the strength of a shockwave is determined by the flow turn angle]
This message was edited 2 times. Last update was at 2020/01/22 17:43:15
Guardsmen, hear me! Cadia may lie in ruin, but her proud people do not! For each brother and sister who gave their lives to Him as martyrs, we will reap a vengeance fiftyfold! Cadia may be no more, but will never be forgotten; our foes shall tremble in fear at the name, for their doom shall come from the barrels of Cadian guns, fired by Cadian hands! Forward, for vengeance and retribution, in His name and the names of our fallen comrades!
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Citation is 3e Eldar Codex.
Frisbees turn in flight because the relative air velocity over one side of it is different than the relative velocity over the other side. One side experiences a faster airflow, and therefore generates more lift and more drag than the other side. They will always do this, it's a fact of aerodynamics.
Spinning rifle bullets do not experience this because the axis of rotation is parallel to the direction of travel.
As for a molecule thick frisbee, it will experience drag from skin friction & the boundary layer which doesn't care how thick it is [only it's surface area], and it will experience shockwave drag which is theoretically affected by how thick it is [the strength of a shockwave is determined by the flow turn angle]
So is this why shuriken catapults are 12" (18" for the ASC) range instead of the 30" of bolt rifles?
So is this why shuriken catapults are 12" (18" for the ASC) range instead of the 30" of bolt rifles?
Well, certainly not the actual reason, since I highly doubt the stats of "a gun that shoots ninja stars" are in any way derived from anything that might even remotely resemble reality. If you're going to postulate something so ridiculous in the first place, do you think you care about the variety of reasons that there are currently no in-production weapons that might be described as a gun that shoots ninja stars?
The actual reason was that somebody wanted it to be different in stats and more importantly playstyle than a space marine with a bolter or a guardsman with a lasgun.
Once you've decided on what you want, then you find physical justification for it. In this case, it basically boils down to: "a gun that shoots ninja stars is actually pretty stupid".
This message was edited 2 times. Last update was at 2020/01/22 18:24:20
Guardsmen, hear me! Cadia may lie in ruin, but her proud people do not! For each brother and sister who gave their lives to Him as martyrs, we will reap a vengeance fiftyfold! Cadia may be no more, but will never be forgotten; our foes shall tremble in fear at the name, for their doom shall come from the barrels of Cadian guns, fired by Cadian hands! Forward, for vengeance and retribution, in His name and the names of our fallen comrades!
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Citation is 3e Eldar Codex.
Frisbees turn in flight because the relative air velocity over one side of it is different than the relative velocity over the other side. One side experiences a faster airflow, and therefore generates more lift and more drag than the other side. They will always do this, it's a fact of aerodynamics.
Spinning rifle bullets do not experience this because the axis of rotation is parallel to the direction of travel.
As for a molecule thick frisbee, it will experience drag from skin friction & the boundary layer which doesn't care how thick it is [only it's surface area], and it will experience shockwave drag which is theoretically affected by how thick it is [the strength of a shockwave is determined by the flow turn angle]
Awesome. Ok, non physicist here. Ignorant questions incoming!
1. But doesn't lift require a thickness? My understanding was that wings require the shape they do so that one side of the wing has more area. That would suggest a molecule-thick projectile wouldn't experience the same effect.
2. So how does shockwave drag work for something with a thickness close to 0?
3. Let's say the Shuriken Catapult has a much higher initial velocity than the rifle bullets. Could it theoretically not reach the same effective range?
Also: Found the bit in 3rd Ed Eldar book. "The downside of the firing mechanism is the lack of rifling on the barrel, which drastically reduces it's accuracy, keeping the weapons effective range below that or standard solid ammunition types of similar size." which . . . okay . . . It is what it is. But it's irritating to have it explicitly stated in-fluff that the Eldar are using inaccurate weapons. One wouldn't peg them for that sort of thing.
This message was edited 2 times. Last update was at 2020/01/22 18:25:25
Waiting for my shill money from Spiral Arm Studios
The thickness of a wing is only a means to an end. What matters is the surface area. Wings are thickened so that the top has more surface than the bottom, creating a lift in the upwards direction. Shurikan would still have lift because they have surface area. It would be different than an airplane wing but it would still be there.
The real reason its problematic is because as soon as the Shurikan start to drift they will be blown off course. Just try throwing a frizzbee in even a slight wind. As soon as the frizzbee gets its flat side caught by the wind it will be tossed aside from its original course. Shurikan would experience the same effect in even completely still air because they are so lightweight.
Self-proclaimed evil Cat-person. Dues Ex Felines
Cato Sicarius, after force feeding Captain Ventris a copy of the Codex Astartes for having the audacity to play Deathwatch, chokes to death on his own D-baggery after finding Calgar assembling his new Eldar army.
As I said, the quote came from the 3rd ed codex and it specifically ascribes the inaccuracy to the lack of rifling. AND it's written as inuniverse training information for imperials, making it as unreliable as the imperial infantrymans uplifting primer...
That line has never been used since that book and in the two previous editions it had a 24" range and was superior to a storm bolter.
From 4th onwards they even describe the avenger catapult as pinpoint accurate despite its function being the same.
To hit hard enough to do damage it needs to be going fast (which it states in the attached quotes). Going fast means it travels far. For something that weighs nothing to do the kind of damage it is described as doing, it must be going VERY FAST. Which means it will also be found very far as well.
You would have to deliberately deisgn it to be bad for all of these requirements to result in a short ranged gun. As rifling has no bearing on the function of the weapon, the comment is completely irrelevant. It would be like saying that a car's speed is affected by its engine not being rifled. It has nothing to do with the object in question.
This message was edited 1 time. Last update was at 2020/01/22 22:18:47
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Citation is 3e Eldar Codex.
Frisbees turn in flight because the relative air velocity over one side of it is different than the relative velocity over the other side. One side experiences a faster airflow, and therefore generates more lift and more drag than the other side. They will always do this, it's a fact of aerodynamics.
Spinning rifle bullets do not experience this because the axis of rotation is parallel to the direction of travel.
As for a molecule thick frisbee, it will experience drag from skin friction & the boundary layer which doesn't care how thick it is [only it's surface area], and it will experience shockwave drag which is theoretically affected by how thick it is [the strength of a shockwave is determined by the flow turn angle]
Awesome. Ok, non physicist here. Ignorant questions incoming!
1. But doesn't lift require a thickness? My understanding was that wings require the shape they do so that one side of the wing has more area. That would suggest a molecule-thick projectile wouldn't experience the same effect.
2. So how does shockwave drag work for something with a thickness close to 0?
3. Let's say the Shuriken Catapult has a much higher initial velocity than the rifle bullets. Could it theoretically not reach the same effective range?
Also: Found the bit in 3rd Ed Eldar book. "The downside of the firing mechanism is the lack of rifling on the barrel, which drastically reduces it's accuracy, keeping the weapons effective range below that or standard solid ammunition types of similar size." which . . . okay . . . It is what it is. But it's irritating to have it explicitly stated in-fluff that the Eldar are using inaccurate weapons. One wouldn't peg them for that sort of thing.
I am not a physicist either. I'm an aerospace engineer, which some may say is "close enough" but at the end of the day I'm happy when I can pretend enough terms of the equation are small enough to ignore so the rest of it is easy to solve and give and answer close enough to reality for the rocket or plane to fly. Advance Disclaimer: fluid flow is modelled using the Navier Stokes Equations. The Navier Stokes Equations are very complicated, and proving that they have a solution at all points and are continuously differentiable is one of the most important unsolved problems in mathematics, and proving or disproving it will win you a lot of money and maybe a nobel prize. My joke about crossing off terms by pretending they're small is entirely accurate, we make assumptions that make terms small, and then cross them off as insignificant, so that we may work with them and get answers that are functionally close enough to reality using just the easy parts. So close enough.
1: No, but to understand why airfoils are shaped the way they are requires an understanding of where lift and drag develop from. The simple explanation is that lift develops from the pressure across the surface of the object [specifically, the components of the pressure force perpendicular to the free stream flow]. Basically, by integrating the pressure force across the surface of the wing and taking the up component, you get the lift. Pressure force is a vector. For the simplest case, a thin, flat, long airfoil at 0 degrees angle of attack, the integration of the pressure over the top surface will be equal to the integration of pressure over the bottom surface, but pointing in the opposite direction, and therefore the total lift will be zero. If you tip the airfoil to a nonzero angle of attack, there will be an experienced pressure differential between the top and the bottom of the airfoil [and also the fluid flow will experience a change in direction, necessitating a reaction force], and the total lift will be upwards. Likewise, making the airfoil asymmetric will affect the velocity of the flow over the airfoil to create a pressure differential.
Now, let's say we have a long cylinder that's rotating in the free stream flow. On the side of the cylinder that's travelling against the flow, the apparent flow velocity is higher than the apparent flow velocity on the side travelling with the flow. Simple vector subtraction, yes? Anyway, this creates lift and drag, and is known as the Magnus Effect [no relation to smiting for 2d6 damage]. A frisbee, or monomolecular ninja star, spinning through the flow will experience the magnus effect pointing to one side, and will thus drift in that direction as it flies. The less fast it spins and the lower the free stream velocity, the less severe the effect. Artillery shells and bullets experience the magnus effect too, however, the effective free stream flow is much lower since it would be the wind across the shell's flight path, as opposed to the velocity of the shell itself, so it only matters in high crosswind and long range.
Theoretically, if you spin less, you'll get less magnus effect. However, if you spin less, you'll also be much more prone to tumbling, which will bring your flight to an end much more quickly than the magnus effect. Spinning also takes energy that could be going to going forward. In general, you want to spin just enough to stay stable and no more.
Drag, of course, develops from a lot of sources. There's aerodynamic drag, which is the element of that integration that points parallel to the free stream flow and perpendicular to lift. There's also skin friction drag, turbulent drag, shockwaves, and etc.
2: Shockwaves are discontinuities in a flow that form in supersonic flows. Oblique shocks form when the flow is forced to change directions and turns inside the corner [imagine a ramp upwards. The supersonic flow is going flat, and then goes up the ramp. An Oblique Shock occurs at the base of the ramp so the flow can turn]. Prandtl-Meyer Expansion Fans are the opposite, when the flow goes around a corner outside the corner [imagine a ramp downwards. The supersonic flow turns and goes down the ramp. An expansion fan occurs at the start of the ramp so that the flow can turn]. A bunch of properties of the flow change when it experience a shock, including density, pressure, and velocity, and energy is required to affect these changes, hence the drag that's generated.
For a supersonic aircraft, this is how the airfoil generates the pressure differential that results in lift. A big curvy bulbous airfoil isn't good for supersonic aircraft, the'd like to have a thin flat plate at an angle, which will generate 2 oblique shocks and 2 expansion fans.
Theoretically, an infinitely thin frictionless plate at 0 angle of attack would go unnoticed by the flow.
Infinitesimal disturbances on a surface generate something called mach waves, which show up on schlieren photographs but have fairly negligible effect on the flow.
Now, one more thing: the boundary layer. Unless the atmosphere is highly rarefied, we can assume a "no-slip condition". That is to say, the air in contact with the surface is moving at the same speed as the surface. Far away from the surface, the flow is moving at the free stream velocity. The boundary layer is the region of the air where the flow is accelerating from 0 at the surface of the object to the free steam velocity. It's good when the boundary layer is thin and laminar, but it grows further down the surface until it transitions into turbulent conditions.
3: Yes. If it goes much faster than bullets, it could in theory reach the same effective range. Effective range is governed by two things: ability to hit the target, and ability to kill the target if you hit. If the shuriken was appreciably faster, then it could in theory remain lethal and accurate out to longer ranges just because in the time the deviation from any given acceleration accumulates enough to drive it off target, it'll have traveled further downrange. Of course, there's a lot of stuff in play, and there isn't a rule or anything. That said, when in doubt, make like the 17pdr and go faster until things stop working, then change your shell geometry and material until it works.
On a completely different tangent, have a schlieren photograph of a circle in a supersonic flow I found on google. Kind of cool looking. The black lines are shockwaves.
This message was edited 9 times. Last update was at 2020/01/22 23:03:55
Guardsmen, hear me! Cadia may lie in ruin, but her proud people do not! For each brother and sister who gave their lives to Him as martyrs, we will reap a vengeance fiftyfold! Cadia may be no more, but will never be forgotten; our foes shall tremble in fear at the name, for their doom shall come from the barrels of Cadian guns, fired by Cadian hands! Forward, for vengeance and retribution, in His name and the names of our fallen comrades!
I am not a physicist either. I'm an aerospace engineer, which some may say is "close enough" but at the end of the day I'm happy when I can pretend enough terms of the equation are small enough to ignore so the rest of it is easy to solve and give and answer close enough to reality for the rocket or plane to fly.
Advance Disclaimer: fluid flow is modelled using the Navier Stokes Equations. The Navier Stokes Equations are very complicated, and proving that they have a solution at all points and are continuously differentiable is one of the most important unsolved problems in mathematics, and proving or disproving it will win you a lot of money and maybe a nobel prize. My joke about crossing off terms by pretending they're small is entirely accurate, we make assumptions that make terms small, and then cross them off as insignificant, so that we may work with them and get answers that are functionally close enough to reality using just the easy parts. So close enough.
1: No, but to understand why airfoils are shaped the way they are requires an understanding of where lift and drag develop from. The simple explanation is that lift develops from the pressure across the surface of the object [specifically, the components of the pressure force perpendicular to the free stream flow]. Basically, by integrating the pressure force across the surface of the wing and taking the up component, you get the lift. Pressure force is a vector. For the simplest case, a thin, flat, long airfoil at 0 degrees angle of attack, the integration of the pressure over the top surface will be equal to the integration of pressure over the bottom surface, but pointing in the opposite direction, and therefore the total lift will be zero. If you tip the airfoil to a nonzero angle of attack, there will be an experienced pressure differential between the top and the bottom of the airfoil [and also the fluid flow will experience a change in direction, necessitating a reaction force], and the total lift will be upwards. Likewise, making the airfoil asymmetric will affect the velocity of the flow over the airfoil to create a pressure differential.
Now, let's say we have a long cylinder that's rotating in the free stream flow. On the side of the cylinder that's travelling against the flow, the apparent flow velocity is higher than the apparent flow velocity on the side travelling with the flow. Simple vector subtraction, yes? Anyway, this creates lift and drag, and is known as the Magnus Effect [no relation to smiting for 2d6 damage]. A frisbee, or monomolecular ninja star, spinning through the flow will experience the magnus effect pointing to one side, and will thus drift in that direction as it flies. The less fast it spins and the lower the free stream velocity, the less severe the effect. Artillery shells and bullets experience the magnus effect too, however, the effective free stream flow is much lower since it would be the wind across the shell's flight path, as opposed to the velocity of the shell itself, so it only matters in high crosswind and long range.
Theoretically, if you spin less, you'll get less magnus effect. However, if you spin less, you'll also be much more prone to tumbling, which will bring your flight to an end much more quickly than the magnus effect. Spinning also takes energy that could be going to going forward. In general, you want to spin just enough to stay stable and no more.
Ok, so what I'm reading from that is that the cylinder rotating along it's axis through the air/fluid is in large part being pulled off it's trajectory by some amount in part because of the amount of surface area that is "doing the spinning". The entire side of the cylinder is causing the Magnus Effect. So I'm guessing that a projectile with a monomolecular edge will have very, very little surface area along it's edge to produce a similar effect. Maybe not zero, but certainly much, much less.
In our case the "added" surface area would be the top and bottom of the Shuriken projectile, but the magnus effect on those would essentially counteract. The top and bottom of the Shuriken are traveling at the same rate, the vectors applied (up and down) cancel each other out. So in total I'm thinking there's an infinitesimally small effect pulling the shuriken laterally, and a net 0 effect pulling the spinward side up and down.
Drag, of course, develops from a lot of sources. There's aerodynamic drag, which is the element of that integration that points parallel to the free stream flow and perpendicular to lift. There's also skin friction drag, turbulent drag, shockwaves, and etc.
In mah brain I'm modelling the amount of drag on a monomolecular shuriken as being less than that of a bullet, just based on the cross-section pointing into the flow of air. I suppose with the exception of "skin drag", which could be more as the amount of surface area on the shuriken may be more than that of a bullet. But I don't really know anything about "skin drag", so guessing.
I can understand that even with less drag overall, the effect of drag on the projectile might be greater because a monomolecular disc is going to have very little mass, and thus less momentum if travelling at similar speeds. Although it would appear that one could just increase the velocity and you'd increase your momentum to something comparable.
2: Shockwaves are discontinuities in a flow that form in supersonic flows. Oblique shocks form when the flow is forced to change directions and turns inside the corner [imagine a ramp upwards. The supersonic flow is going flat, and then goes up the ramp. An Oblique Shock occurs at the base of the ramp so the flow can turn]. Prandtl-Meyer Expansion Fans are the opposite, when the flow goes around a corner outside the corner [imagine a ramp downwards. The supersonic flow turns and goes down the ramp. An expansion fan occurs at the start of the ramp so that the flow can turn]. A bunch of properties of the flow change when it experience a shock, including density, pressure, and velocity, and energy is required to affect these changes, hence the drag that's generated.
For a supersonic aircraft, this is how the airfoil generates the pressure differential that results in lift. A big curvy bulbous airfoil isn't good for supersonic aircraft, the'd like to have a thin flat plate at an angle, which will generate 2 oblique shocks and 2 expansion fans.
Theoretically, an infinitely thin frictionless plate at 0 angle of attack would go unnoticed by the flow.
Infinitesimal disturbances on a surface generate something called mach waves, which show up on schlieren photographs but have fairly negligible effect on the flow.
I'm seeing the potential "ideal" Shuriken projectile to be as close to 0 friction and 0 thickness as possible. Soo, maybe something is there?
Now, one more thing: the boundary layer. Unless the atmosphere is highly rarefied, we can assume a "no-slip condition". That is to say, the air in contact with the surface is moving at the same speed as the surface. Far away from the surface, the flow is moving at the free stream velocity. The boundary layer is the region of the air where the flow is accelerating from 0 at the surface of the object to the free steam velocity. It's good when the boundary layer is thin and laminar, but it grows further down the surface until it transitions into turbulent conditions.
I'm having trouble parsing this. It sounds like you are saying that the boundary layer grows as it passes over the surface we're talking about. But again I have to assume that if there's as little perturbation as possible up front because of the thin edge, that the boundary layer will grow across the surface at a much lower rate. No?
3: Yes. If it goes much faster than bullets, it could in theory reach the same effective range. Effective range is governed by two things: ability to hit the target, and ability to kill the target if you hit. If the shuriken was appreciably faster, then it could in theory remain lethal and accurate out to longer ranges just because in the time the deviation from any given acceleration accumulates enough to drive it off target, it'll have traveled further downrange. Of course, there's a lot of stuff in play, and there isn't a rule or anything. That said, when in doubt, make like the 17pdr and go faster until things stop working, then change your shell geometry and material until it works.
So given all this, I'm thinking the monomolecular thickness shuriken could still give fairly reasonable areodynamics if it's thin enough (near 0) and fast enough (faster than a typical rifle bullet), bringing it up to a similar amount of momentum to reduce the effects of drag, the stabilization coming from spinning, and still not much of a net Magnus Effect because of the extremely thin surface area pointing laterally. Perhaps if there was some lateral pull, the predictability of the projectile firing could allow a ranging adjustment similar to how we'd normally provide for bullet drop when aiming at long distances. Just, instead of adjusting vertically, the Eldar would adjust laterally. (or diagonally if correcting for both drop and magnus effect.
Ok, so what I'm reading from that is that the cylinder rotating along it's axis through the air/fluid is in large part being pulled off it's trajectory by some amount in part because of the amount of surface area that is "doing the spinning". The entire side of the cylinder is causing the Magnus Effect. So I'm guessing that a projectile with a monomolecular edge will have very, very little surface area along it's edge to produce a similar effect. Maybe not zero, but certainly much, much less.
In our case the "added" surface area would be the top and bottom of the Shuriken projectile, but the magnus effect on those would essentially counteract. The top and bottom of the Shuriken are traveling at the same rate, the vectors applied (up and down) cancel each other out. So in total I'm thinking there's an infinitesimally small effect pulling the shuriken laterally, and a net 0 effect pulling the spinward side up and down.
Yes, the Magnus Effect I believe only comes from the edge surface, which would be small but existing, which also basically describes the mass of the disk. Theoretically I could prove that it either matters a lot or doesn't matter, but then I'd have to do math and I don't really want to do that, and am just going to observe that since the magnus effect of a frisbee is not small compared to its mass, then the magnus effect of a similarly shaped but smaller object will also not be small compared to its mass.
As a side observation, the Magnus Effect force changes with area [x^2], while the mass changes with volume [x^3], so in theory it'll have a more significant effect on the very small shuriken ammunition than a frisbee of similar proportions but greater size.
As for lift etc, it'll only be 0 at 0 angle of attack. Angle of attack is how "tipped" into the wind the airfoil is, if you tip back you generate lift. To know whether a shuriken or bullet will produce more lift at any given angle of attack, you'd have to consider Cl vs alpha charts for each and consider the planform area of the object. I don't have one for either on me, and most are for infinite wings of a given cross section [nor do I have permission to put ninja stars and bullets inside of wind tunnels to find them]. That said, a bullet shape has a small planform area compared to a disk.
Insectum7 wrote: So given all this, I'm thinking the monomolecular thickness shuriken could still give fairly reasonable areodynamics if it's thin enough (near 0) and fast enough (faster than a typical rifle bullet), bringing it up to a similar amount of momentum to reduce the effects of drag, the stabilization coming from spinning, and still not much of a net Magnus Effect because of the extremely thin surface area pointing laterally. Perhaps if there was some lateral pull, the predictability of the projectile firing could allow a ranging adjustment similar to how we'd normally provide for bullet drop when aiming at long distances. Just, instead of adjusting vertically, the Eldar would adjust laterally. (or diagonally if correcting for both drop and magnus effect.
Yes, something like that, given calm conditions. I imagine the shuriken would probably have more issued with non-ideal conditions than a bullet would though, and would require tighter tolerance the projectile and weapon. But yes, the Eldar probably correct diagonally at any given range.
I think you'd have to go much faster than a typical rifle bullet to achieve similar levels of accuracy and range, and you might have some severe problems with tumbling [and going fast]
At the end of the day, I've never studied the aerodynamics of ninja star guns. I'd have to do experiments, or at least an unpleasant amount of math, to prove anything, This is really just an offering of things that might affect a shuriken catapult ammunition piece in flight. Most of these also affect bullets, but to different degrees, so the question is whether it matters more to a bullet or ninja star.
Of note, a bullet remains lethal long after it's maximum effective range, and the shuricat is officially stated to be range-limited by lack of accuracy, not lack of lethality at that range. [a bolt shell is definitely limited by lack of accuracy, since it's an explosive]
So odds are that some of these forces that are strictly retarding forces, like the skin friction drag and drag from flow separation, are probably not really relevant concerns. What concerns us most are the forces pushing to the side, up or down, which I think that the shuriken definitely experiences more of.
And I guess I'm also somewhat biased, since we can build guns that shoot bladed disks. We just don't because bullets work better.
Spoiler:
Insectum7 wrote: In mah brain I'm modelling the amount of drag on a monomolecular shuriken as being less than that of a bullet, just based on the cross-section pointing into the flow of air. I suppose with the exception of "skin drag", which could be more as the amount of surface area on the shuriken may be more than that of a bullet. But I don't really know anything about "skin drag", so guessing.
I can understand that even with less drag overall, the effect of drag on the projectile might be greater because a monomolecular disc is going to have very little mass, and thus less momentum if travelling at similar speeds. Although it would appear that one could just increase the velocity and you'd increase your momentum to something comparable.
Insectum7 wrote: I'm having trouble parsing this. It sounds like you are saying that the boundary layer grows as it passes over the surface we're talking about. But again I have to assume that if there's as little perturbation as possible up front because of the thin edge, that the boundary layer will grow across the surface at a much lower rate. No?
No?
Does the boundary layer concept make sense to you? For all intents and purposes, we're going to attach our reference frame to the plate. To us, it looks like the plate is standing still and the flow is going around it, like it's in a wind tunnel.
At the surface of the plate, the flow is not moving. This is because of the no-slip condition, which states that the flow sticks to the surface of the plate and does not slide against it [also, the flow sticks to itself]. This is true for basically all non-rarefied gas conditions, we only really discard it if you're dealing with micro-atmosphere in orbit. In the free stream, far away from the plate, the flow is moving at a velocity V. As we go away from the plate, the flow velocity profile is continuous, it smoothly goes from 0 to V as opposed to jumping at any point. This distance where the flow is speeding up from 0 to V is known as the Boundary Layer.
On most of a wing or flying object, the boundary layer is laminar. That means that all the streamlines run parallel to each other, and is the opposite of turbulence. At the leading edge, the boundary layer is laminar and small. However, it grows and becomes thicker over the course of the airfoil, until at some point it becomes turbulent. Turbulent boundary layer is bad, but the laminar boundary layer still produces drag.
The more surface area you have, the more drag will come from the boundary layer unless there are severe differences in where the turbulent transition point is.
A bullet has complete flow separation on the back end of it though, which is probably a lot more drag.
The perturbation at the front of the plate will come from the shockwaves.
This message was edited 8 times. Last update was at 2020/01/24 01:17:31
Guardsmen, hear me! Cadia may lie in ruin, but her proud people do not! For each brother and sister who gave their lives to Him as martyrs, we will reap a vengeance fiftyfold! Cadia may be no more, but will never be forgotten; our foes shall tremble in fear at the name, for their doom shall come from the barrels of Cadian guns, fired by Cadian hands! Forward, for vengeance and retribution, in His name and the names of our fallen comrades!
Thanks for that breakdown, I didn't know drag increased with speed. This is why I find the physics around the catapult so interesting, nothing about it makes sense. Its firing mechanism is most closely aligned to a coil or rail gun (using gravity waves over electricity), but it fires something that no one fires today.
Based on design and description it:
Fires low mass thin flat discs ~20-30mm in diameter
It has a very high rate of fire
It is an accurate infantry weapon (it isn't a spray and pray weapon)
Id be making the numbers up, but I doubt the shuriken weigh more than a gram each (at the thickness indicated, the material would need to be denser than lead to have a higher mass).
Current descriptions state that the gravitic pulse it uses to fire the disc also shears it off a solid core of ammunition, which would itself require a substantial amount of force. One stick is good for hundreds of rounds, so maybe they're 300mm long and therefore the discs are ~1mm thick reach?
Lexicanum states that it's an inaccurate weapon which is what limits it's effective range [IE: the range of 12" is the maximum range at which aimed fire expects to hit anything, not the range the gun can shoot.
Lexicanum is quoting the 3rd ed codex and says that 'due to the lack of rifling in the barrel' it's inaccurate. Which is a nonsense statement in the same vein as 'due to the lack of rifling in the barrel buckshot is inaccurate'. Because Rifling isn't going to have any affect on a disc fired by a linear accelerator... That line disappeared in subsequent codices because it's ridiculous
Have you ever tried to throw a frisbee without spinning it? Have you ever observed the flight of a frisbee even with spin on it?
I see no problem with the declaration that it's range-limited by the lack of ability to hit the thing you're aiming at longer distances. The projectile of choice is undeniably crap.
Yes, lack of rifling doesn't mean that it's not accurate. After all, tank guns are very accurate, and are not rifled at all. Tanks, however, are firing long, thin, dense and finned-stabilized projectiles, not bladed frisbees.
Not that I'm an expert, but I've seen frisbees thrown exceedingly straight and accurately. Generally the curve in a throw, when there is some, is towards the end when it's lost a significant amount of velocity. It would not surprise me if one could make a machine that threw frisbees very straight, consistently
The current description I can find says the projectiles themselves are a molecule thick. I'm trying to picture how that effects drag.
I wonder what the source is for the description of "inaccurate" from lexicanum.
Citation is 3e Eldar Codex.
Frisbees turn in flight because the relative air velocity over one side of it is different than the relative velocity over the other side. One side experiences a faster airflow, and therefore generates more lift and more drag than the other side. They will always do this, it's a fact of aerodynamics.
Spinning rifle bullets do not experience this because the axis of rotation is parallel to the direction of travel.
As for a molecule thick frisbee, it will experience drag from skin friction & the boundary layer which doesn't care how thick it is [only it's surface area], and it will experience shockwave drag which is theoretically affected by how thick it is [the strength of a shockwave is determined by the flow turn angle]
Eldar shuriken weapons are basically high-tech versions of this classic weapon:
Ok, so what I'm reading from that is that the cylinder rotating along it's axis through the air/fluid is in large part being pulled off it's trajectory by some amount in part because of the amount of surface area that is "doing the spinning". The entire side of the cylinder is causing the Magnus Effect. So I'm guessing that a projectile with a monomolecular edge will have very, very little surface area along it's edge to produce a similar effect. Maybe not zero, but certainly much, much less.
In our case the "added" surface area would be the top and bottom of the Shuriken projectile, but the magnus effect on those would essentially counteract. The top and bottom of the Shuriken are traveling at the same rate, the vectors applied (up and down) cancel each other out. So in total I'm thinking there's an infinitesimally small effect pulling the shuriken laterally, and a net 0 effect pulling the spinward side up and down.
Yes, the Magnus Effect I believe only comes from the edge surface, which would be small but existing, which also basically describes the mass of the disk. Theoretically I could prove that it either matters a lot or doesn't matter, but then I'd have to do math and I don't really want to do that, and am just going to observe that since the magnus effect of a frisbee is not small compared to its mass, then the magnus effect of a similarly shaped but smaller object will also not be small compared to its mass.
As a side observation, the Magnus Effect force changes with area [x^2], while the mass changes with volume [x^3], so in theory it'll have a more significant effect on the very small shuriken ammunition than a frisbee of similar proportions but greater size.
As for lift etc, it'll only be 0 at 0 angle of attack. Angle of attack is how "tipped" into the wind the airfoil is, if you tip back you generate lift. To know whether a shuriken or bullet will produce more lift at any given angle of attack, you'd have to consider Cl vs alpha charts for each and consider the planform area of the object. I don't have one for either on me, and most are for infinite wings of a given cross section [nor do I have permission to put ninja stars and bullets inside of wind tunnels to find them]. That said, a bullet shape has a small planform area compared to a disk.
Insectum7 wrote: So given all this, I'm thinking the monomolecular thickness shuriken could still give fairly reasonable areodynamics if it's thin enough (near 0) and fast enough (faster than a typical rifle bullet), bringing it up to a similar amount of momentum to reduce the effects of drag, the stabilization coming from spinning, and still not much of a net Magnus Effect because of the extremely thin surface area pointing laterally. Perhaps if there was some lateral pull, the predictability of the projectile firing could allow a ranging adjustment similar to how we'd normally provide for bullet drop when aiming at long distances. Just, instead of adjusting vertically, the Eldar would adjust laterally. (or diagonally if correcting for both drop and magnus effect.
Yes, something like that, given calm conditions. I imagine the shuriken would probably have more issued with non-ideal conditions than a bullet would though, and would require tighter tolerance the projectile and weapon. But yes, the Eldar probably correct diagonally at any given range.
I think you'd have to go much faster than a typical rifle bullet to achieve similar levels of accuracy and range, and you might have some severe problems with tumbling [and going fast]
At the end of the day, I've never studied the aerodynamics of ninja star guns. I'd have to do experiments, or at least an unpleasant amount of math, to prove anything, This is really just an offering of things that might affect a shuriken catapult ammunition piece in flight. Most of these also affect bullets, but to different degrees, so the question is whether it matters more to a bullet or ninja star.
Of note, a bullet remains lethal long after it's maximum effective range, and the shuricat is officially stated to be range-limited by lack of accuracy, not lack of lethality at that range. [a bolt shell is definitely limited by lack of accuracy, since it's an explosive]
So odds are that some of these forces that are strictly retarding forces, like the skin friction drag and drag from flow separation, are probably not really relevant concerns. What concerns us most are the forces pushing to the side, up or down, which I think that the shuriken definitely experiences more of.
And I guess I'm also somewhat biased, since we can build guns that shoot bladed disks. We just don't because bullets work better.
Insectum7 wrote: In mah brain I'm modelling the amount of drag on a monomolecular shuriken as being less than that of a bullet, just based on the cross-section pointing into the flow of air. I suppose with the exception of "skin drag", which could be more as the amount of surface area on the shuriken may be more than that of a bullet. But I don't really know anything about "skin drag", so guessing.
I can understand that even with less drag overall, the effect of drag on the projectile might be greater because a monomolecular disc is going to have very little mass, and thus less momentum if travelling at similar speeds. Although it would appear that one could just increase the velocity and you'd increase your momentum to something comparable.
Insectum7 wrote: I'm having trouble parsing this. It sounds like you are saying that the boundary layer grows as it passes over the surface we're talking about. But again I have to assume that if there's as little perturbation as possible up front because of the thin edge, that the boundary layer will grow across the surface at a much lower rate. No?
No?
Does the boundary layer concept make sense to you? For all intents and purposes, we're going to attach our reference frame to the plate. To us, it looks like the plate is standing still and the flow is going around it, like it's in a wind tunnel.
At the surface of the plate, the flow is not moving. This is because of the no-slip condition, which states that the flow sticks to the surface of the plate and does not slide against it [also, the flow sticks to itself]. This is true for basically all non-rarefied gas conditions, we only really discard it if you're dealing with micro-atmosphere in orbit. In the free stream, far away from the plate, the flow is moving at a velocity V. As we go away from the plate, the flow velocity profile is continuous, it smoothly goes from 0 to V as opposed to jumping at any point. This distance where the flow is speeding up from 0 to V is known as the Boundary Layer.
On most of a wing or flying object, the boundary layer is laminar. That means that all the streamlines run parallel to each other, and is the opposite of turbulence. At the leading edge, the boundary layer is laminar and small. However, it grows and becomes thicker over the course of the airfoil, until at some point it becomes turbulent. Turbulent boundary layer is bad, but the laminar boundary layer still produces drag.
The more surface area you have, the more drag will come from the boundary layer unless there are severe differences in where the turbulent transition point is.
A bullet has complete flow separation on the back end of it though, which is probably a lot more drag.
The perturbation at the front of the plate will come from the shockwaves.
*A few youtube videos, Wikipedia and diagram searches later* Fascinating! The no-slip condition is really not what I would have expected at all, especially the idea that under perfect conditions (zero turbulence) the air molecules on the surface of a wing would have 0 relative velocity to the surface. Although the more I think about it the more it's obvious that I've seen evidence of no-slip in the form of smoke trails or fluid mechanics simulations. What a drag. Though it must not net that much drag if it's still doing better than a bullet with it's flat rear end.
Thanks for taking the time, I learned a thing!
Makes me want to build a ghetto Shuriken Catapult device and try various solutions to see just how far and accurately one could sling a small metal disc.
So I'm going with the idea that one reason the Eldar favor the Shuriken Catapult because it's ammunition capacity is huge, given that each disc is only a molecule thick. The range in-game still bugs me though, especially as Bolt Rifles are now pushed out to 30". Thet range disparity is aggravating.
Waiting for my shill money from Spiral Arm Studios
Well, Bolt rifles have a number of advantages. 1) The rocket stage of the ammo ensures that it continues to accelerate once it leaves the barrel. 2) the longer rifled barrel means higher velocity+range over a regular bolter.
Self-proclaimed evil Cat-person. Dues Ex Felines
Cato Sicarius, after force feeding Captain Ventris a copy of the Codex Astartes for having the audacity to play Deathwatch, chokes to death on his own D-baggery after finding Calgar assembling his new Eldar army.
Grey Templar wrote: Well, Bolt rifles have a number of advantages. 1) The rocket stage of the ammo ensures that it continues to accelerate once it leaves the barrel. 2) the longer rifled barrel means higher velocity+range over a regular bolter.
Grey Templar wrote: Well, Bolt rifles have a number of advantages. 1) The rocket stage of the ammo ensures that it continues to accelerate once it leaves the barrel. 2) the longer rifled barrel means higher velocity+range over a regular bolter.
Sure seems like no1 makes no2 superfluous.
Not really. Both can work together. And indeed thats the point.
Bolters are based on the real life Gyrojet firearms. Basically a gun that fired a rocket instead of a normal bullet. the downside was that the gyrojet rounds were non-lethal within 30 ft of the barrel, you could literally put your finger down the barrel and keep the projectile from accelerating out, and they were insanely inaccurate(because the rockets sucked).
However, bolters add a normal smokeless powder charge inside a casing like a regular firearm. This means the bullet has an initial charge that gets it to lethal velocities immediately and it can take advantage of rifling(spin stabilization). Then via space handwavium the rocket stage works fine and doesn't cause it to spin off wildly.
So basically, its a normal bullet with an added rocket stage for additional power and range.
Self-proclaimed evil Cat-person. Dues Ex Felines
Cato Sicarius, after force feeding Captain Ventris a copy of the Codex Astartes for having the audacity to play Deathwatch, chokes to death on his own D-baggery after finding Calgar assembling his new Eldar army.
Though it must not net that much drag if it's still doing better than a bullet with it's flat rear end.
