Shockwave formula: Time to put some limits

[M3X_2.0]

Hello. After months using this new method, it's time to put some limits, as the title says. The formula is

(Density of Air/Time^2)*(Radius of Blast Wave/Ratio of Specific Heat of Air)^5

This formila is used to calculate shockwave of explosions or even physical attacks that caused a shockwave. But some people are abusing. Exaple: Attack is X, then you calc the shockwave and get 2X. It doesn't make any sense for the shockwave being stronger than the attack itself. This should be a good point to consider after calculating feats with this formula. And we should understand wich shockwaves should be calculated, originated by explosions only or literally all.

 

[Damage3245]

Watching this thread, because I definitely think this is a valid issue.

 

[M3X_2.0]

@Ugarik @DontTalkDT @Spinosaurus75DinosaurFan

 

[Rocker1189]

I believe it should be clarified that the shockwave did not show damage for this to be applicable it is quite a big case in fiction where the shockwave shows superior damage to the initial move. But if it doesnt show damage then yeah I agree with this.

 

[M3X_2.0]

@Dargoo_Faust

 

[TheRustyOne]

Is it a issue, I'm not familiar with how many calcs that use this.

Limiting it to explosions seems wrong. I need more clarification on that, what do you mean? Say a character isn't capable of producing explosions, but the wind pressure he created shatters multiple buildings, would that not qualify for the formula even though it's not a detonation?

I do agree that creating some wind that don't show any power, or just shakes some trees shouldn't be eligible for this formula.

 

[M3X_2.0]

I am not suggesting this, limiting it to explosions. I gave an example and said that we should discuss this first.

 

[M3X_2.0]

bumpo

 

[NotSoPrimal]

Bump

 

[Damage3245]

To give some context, the formula appears to be taken from here where it was used to estimate the yield of an atomic explosion.

 

[NotSoPrimal]

To give some context, the formula appears to be taken from here where it was used to estimate the yield of an atomic explosion.

Thanks for providing a reference for those who didn't know.

 

[Imaginym]

Apologies if this is off-topic or out of place for me to ask, but I'd like to ask about stuff on this topic:
If there's an explosion that itself generates a shockwave, is it valid to calculate both the explosion's yield and the shockwave's yield, then combine the two & apply that to the source of the explosion/shockwave?

Also, in which circumstances are the limitations being proposed in this thread to be applied?
When the shockwave's damage is less than the source's damage? When the shockwave's damage is greater than the source's damage? When the shockwave's is greater?
What circumstances are valid to use the formula in, & what circumstances are valid to apply the limitations in?

 

[DemonGodMitchAubin]

This definitely needs to be checked out, I'm the one who normalized usage of this calculation, this is the calculation I was told to use for shockwaves by AlexSolo, so I would like Don'tTalk to look over it and make sure it is acceptable to be used

 

[Dargoo_Faust]

The formula was specifically made to estimate the energy released by an atomic bomb through air.

The reason that it gives such inflated values for impacts that are clearly less than the shockwave value is because those aren't explosions, and the assumptions that were used to create the blast wave formula do not apply to pressure waves generated by things that aren't explosions.

It is not calculating the energy of the blast wave. It is calculating the energy of a (nuclear) explosion that caused a blast wave. There's a difference.

 

[DemonGodMitchAubin]

So this would only apply to calcs that use nuclear explosion shockwaves?

 

[Damage3245]

That makes sense to me.

 

[M3X_2.0]

I would like to see what Ugarik has to say too

 

[Dargoo_Faust]

So this would only apply to calcs that use nuclear explosion shockwaves?

It can probably apply to regular explosions too, since those are similar enough to nukes, however I'm no expert on the specific differences between nuclear/conventional explosions outside of yield so there might be factors I'm not aware of.

But yeah, in case someone needs to know where I'm saying this from:

In response to an inquiry from the British MAUD Committee, G. I. Taylor estimated the amount of energy that would be released by the explosion of an atomic bomb in air. ... The yield of the explosion was determined by using the equation E=(p/t^2)(r/C)^5

It calculates explosive yield and not the energy purely associated with the pressure wave. So when we apply it to impacts, the equation is assuming there is also a fireball at the center of the shockwave that doesn't exist, hence the inflation.

 

[DontTalkDT]

That formula is the result of dimensional analysis. I think using explosion formulas usually makes more sense than this. It's the same application case (all our explosion calcs are shockwave calcs), but they usually are build using better data.

 

[M3X_2.0]

So, we should not use this formula and stick with ground explosion and air bust?

 

[DontTalkDT]

I would say so.

 

[M3X_2.0]

ok, thanks. You can close this thread (if you have the power to do so) or Dargoo.

 

[Dargoo_Faust]

I'll compile a list of calculations affected by this change.

 

[M3X_2.0]

I will create another thread to adress this issue, Dargoo

 

[Dargoo_Faust]

Well I think this effects such a massive number of calcs that more calc members should be here to comment, however it is pretty cut and dry here.

 

[Damage3245]

I don't think it is a massive number of calcs. I've only been seeing the formula come up in calcs in recent time.

It would still be good to have a list of the ones affected.

 

[DemonGodMitchAubin]

I don't think any of my shockwave calcs are currently being used, but I can move them from pages if they are, kinda sucks that equation was removed, it led to some fun and cool caclualtions

 

[Dargoo_Faust]

Okay, so M3X or me seems to have misunderstood something DontTalk posted here.

@DontTalkDT

Are you talking about applying explosion formulas to feats that aren't explosions? M3X seems to think you're saying that, if an impact (such as a punch or physical attack) causes a shockwave, we should use an explosion formula to get the yield of the impact.

Which is just silly, because explosion formulas are including the energy released by the fireball, which isn't present in (most) physical impacts.

 

[M3X_2.0]

No, I didn't say anything about impact. I made it clear

 

[Dargoo_Faust]

No, I didn't say anything about impact. I made it clear

I am considering a "physical attack that caused a shockwave" as per what your OP mentions, to be an impact for the sake of my comment, even if you didn't say the word specifically.

 

[M3X_2.0]

I said that now we can calc the shockwave, and not ONLY the fireball/explosion

 

[KLOL506]

None of my calcs use this formula and nor is it on the Explosion Yield Calculations page anyway so... yeah, can't help here.

Also nah, first time I saw the new formula is in a Bleach calc. So it's not as big of a widespread issue as y'all think.

 

[Dargoo_Faust]

I said that now we can calc the shockwave, and not ONLY the fireball/explosion

Our explosion formulas aren't for calcing shockwaves, they're for calcing explosions.

DT is saying that instead of using the shockwave calc for explosions we should use our standard explosion formulas.

 

[M3X_2.0]

That formula is the result of dimensional analysis. I think using explosion formulas usually makes more sense than this. It's the same application case (all our explosion calcs are shockwave calcs), but they usually are build using better data.

I am not sure

 

[Dargoo_Faust]

I am not sure

All of our explosion calcs are shockwave calcs because the thing that's being calced by the formula for shockwaves is literally the full explosive yield. This is what's being said here.

There is no explosion (specifically a fireball) present in physical attacks that just happen to cause shockwaves, ergo explosion calcs don't apply.

 

[M3X_2.0]

I want to read what DT has to say, because I don't trust you anymore after the "impact" thing in the Discord server

 

[Dargoo_Faust]

I want to read what DT has to say, because I don't trust you anymore after the "impact" thing in the Discord server

Well, I'm sorry that calling a "physical attack that causes a shockwave" an "impact" harmed your ability to trust me, but that's literally describing an impact.

It's just linguistics.

 

[DontTalkDT]

Are you talking about applying explosion formulas to feats that aren't explosions? M3X seems to think you're saying that, if an impact (such as a punch or physical attack) causes a shockwave, we should use an explosion formula to get the yield of the impact.

Which is just silly, because explosion formulas are including the energy released by the fireball, which isn't present in (most) physical impacts.

Actually the nuke based explosion formula is for calcing shockwaves. We subtract the fraction that in nukes is energy not used for shockwaves from the total result, in the standard method we use.
The ground-based one is only for explosions, though.

 

[Damage3245]

Here is the list of calcs affected by the removal by the way. Not a large number.

 

[M3X_2.0]

press F for Shinra's calc