Is a Supersonic Projectile possible?

[Rezialn]

How can a single PC fire a super sonic projectile? No peasent railguns. The PC should be able to use the super sonic projectile without a huge amount of preparation, and should be able to carry around any required materials.

Let's say no real restrictions beyond that a single PC should be able to reasonably manage it. The lower level it's possible to pull off at, the better.

[avr]

Sure. I'm pretty sure that I worked out once that a character with far shot, rapid shot, high BAB and a returning boomerang qualified, which implies that a bow with minimal shenanigans would have to be firing supersonic arrows also to hit a target at max range in the same round.

[Kelb_Panthera]

You're going to need to be a little more specific in your restrictions.

IIRC, the maximum, fully optimized range for an arrow, when compared with the fact that an arrow has to cover that distance in as little time as a hurled dagger, as thrown by an untrained commoner, covers 50ft, results in an arrow that approaches or even slightly exceeds C. Even if I'm misremembering, I -know- it exceeded the speed of sound by several fold.

[Rezialn]

Let's say no real restrictions beyond that a single PC should be able to reasonably manage it. The lower level it's possible to pull off at, the better.

[Kalaska'Agathas]

With the Epic Feat Distant Shot (http://www.d20srd.org/srd/epic/feats.htm#distantShot) and a sufficiently distant target, a projectile reaching high mach numbers (and even relativistic velocities) is easy.

In fact, using this feat, firing upon any target greater than six light-seconds (http://www.wolframalpha.com/input/?i=6+light-seconds) distant results in a projectile velocity in excess of C.

[Rabidmuskrat]

In DND, all ranged attacks are 'supersonic'. See, we generally accept rounds to be 6 seconds and all attacks hit in the same turn that they are made. It is also possible to extend the range of an archer to over 5000ft. Since it is possible to move first and then attack, we can assume that the attack part must take under 3 seconds, otherwise there would not be time for a move first. So 5000/3 = 1666.67 ft/s which is greater than the speed of sound, about 1200 ft/s. Therefore, your attack must exceed the speed of sound.

Since having this excessive range does not increase damage or armour penetration in any way at closer range, it seems reasonable that there is no change in projectile speed based on the range your character can attack. Therefore, all (at least arrow) attacks travel faster than the speed of sound.

And this does absolutely nothing from a RAW perspective, since we have no idea even whether sound travels the same speed in the DND universe.

[Uncle Pine]

There was a thread one month ago about really long range sniping. (http://www.giantitp.com/forums/showthread.php?t=321808) Counting that an arrow reaches its target in an istant, supersonic projectiles become easily available:


I believe there is a build somewhere on the forum that managed to shoot arrows at more than 40 miles. 40 miles! In an istant. Mach 1 is 0.21126620536069 miles per second. Go nuts. :smallbiggrin:

EDIT: Found it (http://www.giantitp.com/forums/showthread.php?t=253910). Maximum range is 43.2 miles. However, by reading the eagle's cry bow effect in a certain way, you can go up to 56.07 miles with the same build.


Magical or not, those arrows are still travelling at Mach 200+ (assuming that an istant is 1 second, which isn't true because an istant is much less than a second). :smalltongue:

[TroubleBrewing]

Does this mean that, with spell range extending metamagic, it would be possible to fire an Energy Ray (Sonic) spell which moves faster than the speed of sound? :smallconfused:

[Angelmaker]

Does this mean that, with spell range extending metamagic, it would be possible to fire an Energy Ray (Sonic) spell which moves faster than the speed of sound? :smallconfused:

If it hasn't occured to you alrady that it is silly beyond measure having an arrow travel at mach 40 or the speed of a projectile increasing depending on the distance of the target as the only variable changed, then here is your answer:

Dpending on the time you assume for the attack needed to hit it is either yes or no. If you assume the spell travels more than 1.126 ft per second then yes. Which it does not if you assume 3 seconds casting time and travel time ( move and standard attack ) . Otoh if you quicken metagmagic the spell also then maybe it is only two seconds for the spell to hit?

This is a silly question and as far as I read it ALL your actions in your round are instantaneous. Otherwise, if you would have to measure the relative speeds of attacks you could have hilarious effects like wizard a killing wizard b while wizard b's projectile is still taveling and then killing wizard a after he has already been hit. It does not work that way. :smallsigh:

Or multiple iterative attacks would have to be solved one after another from different combatants. Kelb mentiones projectiles traveling at the speed of light and I am sure in terms of raw this is pretty much true, because of how ranged attacks are resolved.

Edit: if you need the illusion of having supersonic spells just quicken a sonic boom afteer evéry spell or take leadership and grab a bard cohort who casts a sonic boom after each one of your sprlls. :smallbiggrin:

[Uncle Pine]

Funny thing: if you combine Malphas' bird's eye viewing, Distant Shot and a way to planeshift your summoned dove/raven, you can shoot arrows to targets on other planes. Find a way to shoot drills and you're done. :smallcool:

[rmnimoc]

Does this mean that, with spell range extending metamagic, it would be possible to fire an Energy Ray (Sonic) spell which moves faster than the speed of sound?
I'd say so because screw physics, I've got magic. Or because metamagic that manipulates range and area of effect do so with spacial manipulation.

Also:
1. Get planar ring gates.
2. Drop one on the material plane.
3. Drop one on a time-accelerated plane.
4. Punch someone through the ring gate.
Since F=MA the punch will single-handedly cause all the catgirls everywhere to implode. All of them.

[TuggyNE]

I'd say so because screw physics, I've got magic. Or because metamagic that manipulates range and area of effect do so with spacial manipulation.

Also:
1. Get planar ring gates.
2. Drop one on the material plane.
3. Drop one on a time-accelerated plane.
4. Punch someone through the ring gate.
Since F=MA the punch will single-handedly cause all the catgirls everywhere to implode. All of them.

*tears of joy*

[gomipile]

Funny thing: if you combine Malphas' bird's eye viewing, Distant Shot and a way to planeshift your summoned dove/raven, you can shoot arrows to targets on other planes. Find a way to shoot drills and you're done. :smallcool:

That, and do it while piloting a construct the size of galaxies.

[Cicciograna]

1) Build Chuck E. Cheese (http://community.wizards.com/forum/previous-editions-character-optimization/threads/1164211) (or any other build who runs pretty fast).
2) Give him a javelin.
3) Make him run, and thorw the javelin when top speed is reached.
4) ...
5) Profit!

Relativity notwithstanding, obviously.

[Kelb_Panthera]

Technically, the speed of sound is a variable. Its actual value depends on the medium it's traveling through. Generally when people talk about the speed of sound they're talking about the speed of sound in normal atmosphere at sea level.

So, technically, sound can travel faster than the speed of sound.

:biggrin:

[supermonkeyjoe]

1) Build Chuck E. Cheese (http://community.wizards.com/forum/previous-editions-character-optimization/threads/1164211) (or any other build who runs pretty fast).
2) Give him a javelin.
3) Make him run, and thorw the javelin when top speed is reached.
4) ...
5) Profit!

Relativity notwithstanding, obviously.

It will travel exactly as far and as fast as a javelin thrown by someone standing still according to the rules, a 200 foot high person throwing a 250 foot long javelin would still only be able to throw it 150' max according to the rules

[JusticeZero]

The other issue is that sound traveling at a finite speed is a rules quirk from RAW in Reality. That rules quirk isn't referenced in the D&D physics texts PHB and DMG, etc. As such, it's meaningless.

[Powerfamiliar]

The other issue is that sound traveling at a finite speed is a rules quirk from RAW in Reality. That rules quirk isn't referenced in the D&D physics texts PHB and DMG, etc. As such, it's meaningless.

Yep an arrow traveling at the speed of sound still does 1d8 damage, just like when the commoner at the end of the peasant railgun lets go of the item it just falls to the ground with no effect. the same RAW quirks that let you break reality give you no bonuses RAW.

[Kalaska'Agathas]

Technically, the speed of sound is a variable. Its actual value depends on the medium it's traveling through. Generally when people talk about the speed of sound they're talking about the speed of sound in normal atmosphere at sea level.

So, technically, sound can travel faster than the speed of sound.

:biggrin:

Incidentally, the speed of light also varies depending upon the medium it's passing through (though C, which is the speed of light in a vacuum, is still probably the hard limit). And, when it passes through a medium at a velocity greater than the speed of light in that medium, you get this cool blue glow called Čerenkov radiation (http://en.wikipedia.org/wiki/%C4%8Cerenkov_radiation).

Not that it changes anything regarding the terminal effects of the projectile, in D&D.

[Snowbluff]

I'd say so because screw physics, I've got magic. Or because metamagic that manipulates range and area of effect do so with spacial manipulation.

Also:
1. Get planar ring gates.
2. Drop one on the material plane.
3. Drop one on a time-accelerated plane.
4. Punch someone through the ring gate.
Since F=MA the punch will single-handedly cause all the catgirls everywhere to implode. All of them.

The fist is moving at normal speed relative to the material plane.

Also, a waste of gates. Use a black hole instead if you want to get rid of something.

[Erik Vale]

How can a single PC fire a super sonic projectile? No peasent railguns. The PC should be able to use the super sonic projectile without a huge amount of preparation, and should be able to carry around any required materials.

Let's say no real restrictions beyond that a single PC should be able to reasonably manage it. The lower level it's possible to pull off at, the better.

Distance [or other name] weapon property, a epic one. Lets you shoot as far as you can see with no penalty. LOS at ground it supposed to be 8 k, done in 6 seconds for a average speed of just under mach 4.5

I say average, because an arrow going at mach 4.5 would be doing a lot more damage.

[Uncle Pine]

I was thinking... Talking is what? A free action? A nonaction? What's the max distance you can talk to someone (without relying on spell like message, that is)? We know that sounds goes at... well, the speed of sound, and if we find out the max distance someone could hear you speaking we could easily determine what's the speed of sound in D&D. I have a hunch that'll be higher than real world speed of sound.

[Maginomicon]

A Masterwork box/xbow can get the mundane "Long Range" construction property (Dragon Magazine #358 page 42) to get +20 to its RI for 100gp.

A flight arrow (Dragon Compendium page 110) gives +25 to the bow's RI for 0.5gp each.

Thus, a masterwork composite longbow (RI 110) that's constructed to be long range (RI 130) firing a flight arrow (RI 155) can fire to its maximum range (1550 ft) in 6 seconds. That's 176.136 mph or 23.14% mach 1.

The bow costs a mere 500gp (100+300+100) with 0.5gp for each arrow.

[TuggyNE]

I was thinking... Talking is what? A free action? A nonaction? What's the max distance you can talk to someone (without relying on spell like message, that is)? We know that sounds goes at... well, the speed of sound, and if we find out the max distance someone could hear you speaking we could easily determine what's the speed of sound in D&D. I have a hunch that'll be higher than real world speed of sound.

It's a free action, and Listen checks can be pumped probably over 100. Combine that with a really terrible Move Silently check or the sound of a battle, and you can figure out that it's probably somewhere well over a thousand feet. Unfortunately, we don't know how long free actions take, just that they're probably less than a second.

[Maginomicon]

That (258 feet/second) doesn't even reach real-world known limits.

Arrows have been loosed at speeds of 294 feet/second.

http://www.huntersfriend.com/carbon_arrows/hunting_arrows_selection_guide_chapter_5.htm

And?

I'm just saying, if you want a mundane base on which to build a shot to a speed of mach 1, there you go. 500.5 gp for almost 25% of the way there and you don't even have to have particular skill.

[Uncle Pine]

It's a free action, and Listen checks can be pumped probably over 100. Combine that with a really terrible Move Silently check or the sound of a battle, and you can figure out that it's probably somewhere well over a thousand feet. Unfortunately, we don't know how long free actions take, just that they're probably less than a second.

We don't know how much time it takes for an arrow to reach its target either. We only know that it strikes its target almost istantly, which it's undoubtedly less than a second (as for the time needed to perform a free action, since there's no limit on the number of free action/round).
The above could reasonably lead us to say that "free actions" and "istant" are comparable units of time (note: obviously not RAW, it's mere speculation). So, if it's marginally possible for someone to hear something that's at least 56.07 miles away, this would turn the fastest arrow ever shot into a NOT supersonic projectile (if we assume the premises to be true).

[Talderas]

That (258 feet/second) doesn't even reach real-world known limits.

Arrows have been loosed at speeds of 294 feet/second.

That's assuming a flight time of 6 seconds which is vastly underestimated. Flight time of an arrow should be static and not dependent on how many attacks you have per round. Figure out the true maximum of how many attacks can be fired in a single turn to figure out flight time (ignore epic levels and magic).

The speed of sound is a little under 1,125 ft/s (1,116 ft/s to be precise) but that's a nice round number for D&D purposes and this purpose specifically. A dragonbone composite greatbow has a range increment of 150ft with 15 increments using Far Shot. That makes the max range for that bow 2,250ft. Using those two figures we can see that an arrow must have a flight time of 2 seconds or less to achieve supersonic speeds.

BAB - 4 attacks
Arrow Swam - +2 attacks
Rapid Shot - +1 attack (arrow swarm doesn't prevent using rapid shot and vice versa)
Whirling Frenzy - +1 attack

So that means a non-magically enhanced archer can fire 8 arrows during a full attack. 8 arrows in 6 seconds means 0.75 seconds of flight time per arrow. This is well below our mark of a 2 second flight time but what does this translate to?

2,250ft / 0.75s = 3,000 ft/s

If you can get the flight time down to 0.4 seconds (cut in half) then the arrow is not just supersonic.... it's hypersonic.

[Talderas]

You're assuming one arrow has to land before the next one is loosed.

That is not an assumption. That is a requirement. You may use some house rules for handling how combat works but damage is resolved immediately after a successful attack roll which would necessitate that an arrow must reach its target before the second arrow is fired. For further emphasis page 143 of the PHB even says for full attack action...


You do not need to specify the targets of your attacks ahead of time. You can see how the earlier attacks turn out before assigning the later ones.

[georgie_leech]

Maybe Adventurer's are so skilled that the second they loose an arrow/fling a dagger/hurl a hand axe they know whether it will do damage and whether it will be lethal. This explains why Archery gets so little love; the style comes with nigh-prescience by default, so it doesn't need anything else.

[Gotterdammerung]

The first level spell Launch Item moves pretty darn fast. At caster level one it goes 440 feet in an instant. The magic in the spell isn't solely devoted to propulsion, a line of text specifically describes the spell also protecting the launched item from being destroyed by the sudden acceleration. Im not exactly sure how fast the item is moving as it is hard to define an instant in specific units of time. If you further want to add in Enlarge spell metamagic and some warwizard of cormyr levels and boost up your caster level you can get that item going super fast. 1100 feet +110 feet per caster level in an instant is supa fast.

[Uncle Pine]

Maybe Adventurer's are so skilled that the second they loose an arrow/fling a dagger/hurl a hand axe they know whether it will do damage and whether it will be lethal. This explains why Archery gets so little love; the style comes with nigh-prescience by default, so it doesn't need anything else.

Of course adventurers would know whether the arrow/dagger/throwing axe they just used to attack their target hit or not because in the former case they'd feel the urge to roll for the damage.