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Active Sonar: Air to Water


indy523

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Hi everone

 

Basic science from using Google says

 

Speed of Sound is the following

Air 343 m/s normal Atmosphere 20 degree C

Water 1484 m/s

 

The average human reaction time to audio stimulus (which I place Sonar for this purpose) is 0.17 sec

 

Thus allotting for the fact that the sound must travel to the location and back this means the range for reaction is as follows (Reaction Time (0.17) x Speed of Sound in Format /2)

 

Air         29.1m

Water  126.1m

 

So how do I reflect this is the game to make water a better medium for perception than air.

 

I could use the limited range penalty but this is already at -1/4L the lowest allowed so no differentiation between water and air could be made and in reality the limitation does not mean that sonar can't see past 30m in air, just that it distorts it.  If the target is 60m away than it is twice as long to the reaction time.  It will essentially appear 0.17 seconds further back in time.

 

So what if I do it this way

 

I assume that the 126m, one football field length for water is not that far off than normal sight because sight is affected by wind and other items as snipers try to hone in on where the target is and the distortion at two football fields is small enough one 0.17 second interval that the mind of the Sonar user can calculate and allot for the distance.  Plus sight cues have a 0.27 sec delay anyways.  So I treat Active Sonar in Water for Telescopic and OCV range modifiers the same for ease of game rules..

 

I add a limitation Double or Triple Range Modifiers for Active Sonar Range penalties with the condition only in Air not in water.  This can be thought of as a 1/4L for each increase at 1x .  I could assume this is reduced by 1/4 for the not in water condition.  So if this is bought as 3x multiplier for range, not in water (-1/2L reduced by +1/4 to -1/4L) and I use the by one point chart then 28m is (-5*3) or 15 if that sense has to be used to target things in air.

 

The character could by Telescopic Range enhancements for the sense and range penalty levels  to reduce the penalty and could limit the cost to only in air if they so wished or bought reductions that worked in Air or water and separate reductions limited for air to account for the penalty.

 

A similar distortion system could be applied to starship sensors bought to a mega scale level that exceeds the speed of light (300,000,000 m/s).

 

What do you think?

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Wow, is Hero the right game for you!

 

Every GM gets to decide when/how to implement the laws of physics are in games that essentially rely on ignoring the laws of physics (well, in Champions, anyway).

The key thing is not "what would my physics professor say?", but "what do you want to happen in your game?"

 

If you and your players love the idea of using physics wherever possible, and you don't mind the extra possible fiddliness ("If I'm flying 20m above the ocean using sonar to find something 60m below, what is my modifier again? What if I'm 60m below the water using sonar to track something 20m above?"), then you go for it!

"The Physics of Superheroes" is a brilliant book that let me have fun while actually learning stuff and you should totally look at it*.

 

Alternatively you could call it an "Advanced Transmedium Sonar Device with Automated Distortion Correction", ditch the complexity and everybody is STILL a winner :- )

 

 

*Unless you wrote it, in which case - Hi, James, it's a honour to speak to you...

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I don;t need to replicate the laws of physics exactly but their is a reason SONAR works better in water thsn air and a couple simplified rules can refect this.  Trust me this is the 6th grade version of this.

 

The whole point is do you want a soft sci fi story like Star Wars or Star Trek or di you want harder scifi such as books like Star ship Troopers or Haldemans Fotrever War or books by Forward such as Camelot 30/k.

 

Sometines realism of physics adds more.  For instance  all radar should be bought with the limitation does not work in water since the radio waves diffuse through the water making the mrdium useless.  Each style has its charm.

 

That being said I think doubling range penalties should be a 1/2L increased to -1/4L for not in water.   This makes the penalty -10 in Air. 

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I wasn't being snarky, honest - I really am delighted you are looking at this.

If someone wanted to come up with a list of limitations for powers that better reflect real life, I'd be super happy.

And I'd learn stuff!

 

On the other hand, I really do mean that the level of detail is down to the individual group.

 

Some people like their mooks to use guns like this (Thank you Hyper-man!) :

 

Heckler & Koch P30L (9mm): (Total: 29 Active Cost, 15 Real Cost) RKA 1d6+1 (20 Active Points); OAF (P30L handgun; -1), STR Minimum 9 (STR Min. Cannot Add/Subtract Damage; -1), Real Weapon (-1/4), Beam (-1/4), Required Hands One-Handed (Semi-Automatic; -0), 15 Charges (2 clips of 9mm bullets; -0) (Real Cost: 6) plus RKA 1 point (5 Active Points); OAF (Polygonal Rifling; -1), STR Minimum 9 (STR Min. Cannot Add/Subtract Damage; -1), Beam (-1/4), Real Weapon (-1/4), 15 Charges (2 clips of 9mm bullets; -0) (Real Cost: 1) plus +1 OCV with the P30L (2 Active Points); OAF (-1), Real Weapon (-1/4) (Real Cost: 1) plus +1 to offset Range modifier with the P30L; OAF (-1), Real Weapon (-1/4) (Real Cost: 1) plus +1 to offset Recoil modifiers with the P30L; OAF (Type 1 Recoil Compensator; -1), Side Effects, Side Effect occurs automatically whenever Power is used (+1 to Hearing PER modifiers; -1/2), Real Weapon (-1/4) (Real Cost: 1)

 

Others are perfectly happy with 2d6RKAs, or even just 6d6 blasters.

 

That's why I say that Hero is perfect for you - it lets you tinker to find whatever level of complexity and realism you and your group want.

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I was just typing my response about adding rapid to sonar in water, when Christopher beat me to it. Here are the relevant details which if you squint hard enough kinda match your math. From 6E1 214:

 

 

A character with a Rapid Sense can use that Sense to “read” or otherwise take in or absorb data or sensations faster than normal. At its base level, Rapid lets the character perceive objects 10x faster than normal. Characters can buy Rapid multiple times [...] Rapid doesn’t provide any direct bonuses to PER Rolls. But as a guideline, the GM may assume each level of Rapid counts as +3 with appropriate PER Rolls, only to counteract penalties for performing tasks quickly (see 6E1 59). Thus, with Rapid x10, a character can perceive in a Phase what other characters take 1 Turn to perceive; with Rapid x100, he perceives in a Phase what others need 1 Minute to perceive; and so on.

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I'd think it's a bit of a distraction myself, but if I were to implement it, I'd say just give them a +8 Range mod bonus.  That will make spotting someone with sonar underwater as quick and as easy as spotting them next to you.

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Hey

 

Found the problem.  There is already a limitation that does this.  Innacurate.  IT halves the OCV and reduces the range modifiers to 6m from 8m.  -1/4L

 

For a 0 OCV and range modifier halved to 4m then this is a -1/2L

 

So for my purposes I could state that to have the range modifier affect the targeting senses ability to see as well is an increased of 1/4L to the limitation.  Also one can reduce the range modifiers by 3m and then another 2m (1/2DCV) 2m then 1m (0 DCV) each for another 1/4L increase in the limitation.

 

So buying inaccurate at 1/2 DCV (base 6m) at -1/4L  You can apply the limitation to the SONAR Sense (and it will apply to all attacks that use SONAR to target, set when purchased)  You could then reduce the range mod to 3m for an additional 1/4L and to 1m for 1/4 after that..

 

If you bought the 0 DCV base 4m version you have-1/2L, -1/4L to apply to the sense and then for 1/4L more reduce to 2m for -1/4L and 1m for 1/4L more than that.

 

So  for 1/2 OCV it is 6m, 3m or 1m increments and for 0 DCV it is 4m, 2m or 1m increments.

 

I don't like this as it requires creating a conditional limitation that involves editing the rules but there you go.  I'll have to think about this. 

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I'd think it's a bit of a distraction myself, but if I were to implement it, I'd say just give them a +8 Range mod bonus.  That will make spotting someone with sonar underwater as quick and as easy as spotting them next to you.

 

True but the issue is that using SONAR in Air would be much worse than using sight.

 

If a trained marksman has a normal rifle with a sight he can easily hit a mark 100 to 200 to 300m away without a scope.  Most people would be closer to 200 but lets use 210m as an example.  At 30m the sound has traveled one response increment for a human being to audio stimulus (0.17 seconds) lets increase that to 0.2 seconds for argument.

 

A target at 210m away is 210m/30m or 7 response increment from the shooter.  Thus if at the time the shooter sees the character to make a shot the target turns around and goes the other way the target could have run for 1.2 seconds in another direction before the shooter could notice.  Effectively an aware target could make oneself impossible to hit.  Using Sonar the Range in Air is very limited which is what I am attempting to do above.

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I'd think it's a bit of a distraction myself, but if I were to implement it, I'd say just give them a +8 Range mod bonus.  That will make spotting someone with sonar underwater as quick and as easy as spotting them next to you.

 

True but the issue is that using SONAR in Air would be much worse than using sight.

 

I suspect dstaow assumed you'd only apply the +8 Range mod bonus when in water. You could apply the standard HERO System range modifiers when in air, which stack up pretty fast without Penalty Skill Levels to reduce them.

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I suspect dsatow assumed you'd only apply the +8 Range mod bonus when in water. You could apply the standard HERO System range modifiers when in air, which stack up pretty fast without Penalty Skill Levels to reduce them.

 

Yup.  I figure the base ability is of most use in the air and would get the bonus underwater.  

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OK

 

Thinking out loud on line I checked the 6e2 book on determining OCV and anything that halves or percentages OCV does so after adding in skill levels and 0 OCV counts as 100%.  So one cannot effectively counteract innaccurate with skill levels and the 1/2L 0 DCV not at all.

 

In my Sonar example above I want the range reduction from 8m to 6m to 4m etc. but not the initial OCV percentage.  I need to house rule the system but something that is within the flavor of the rules, balanced to the Inacurate limitation as is that most gms would hopefully accept.

 

So I am doing this.  The reduction in the range increment will be 8m standard, 6m one level, 4m two levels, 2m three levels and 1m four levels.

 

At 1/4L is 1/2 OCV and one level range reduction to 6m or

No reduction in OCV and a 4m range reduction (2 levels) for -1/4L also.

 

At 1/2 is 0 OCV and two levels to 4m so I increase the base to -3/4L

 

These are the base sets

 

No reduction and 4m

1/2 OCV and 6m

  0  OCV and 4m

 

After this every step down is an increase in the limitation by 1/4L

 

Full OCV

Increments

4m -1/4L

2m -1/2L

1m -3/4L

 

1/2 OCV

Increments

6m -1/4L

4m -1/2L

2m -3/4L

1m -1L

 

0 OCV

Increments

No range attacks -1/2L

4m -3/4L

2m -1L

1m  -1&1/4L

 

This seems fair.

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Hmm... if the situation only comes up now and then (i.e. a land based superhero with a Bat motif that uses active sonar finds himself underwater) it falls under "environmental conditions" IMHO. His sonar gets a boost while his sight gets a penalty. And that assumes his special effect allows it to be used at all.

 

If underwater is a common situation, points would need to be spent. Aquaman, who is based underwater, would definitely need to shell out for telescopic sonar only while underwater, or alternatively if he has regular active sonar while swimming, he should suffer a penalty when sucking air. Something like a submarine just buys the sense normally.

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Hmm... if the situation only comes up now and then (i.e. a land based superhero with a Bat motif that uses active sonar finds himself underwater) it falls under "environmental conditions" IMHO. His sonar gets a boost while his sight gets a penalty. And that assumes his special effect allows it to be used at all.

 

If underwater is a common situation, points would need to be spent. Aquaman, who is based underwater, would definitely need to shell out for telescopic sonar only while underwater, or alternatively if he has regular active sonar while swimming, he should suffer a penalty when sucking air. Something like a submarine just buys the sense normally.

I am envisioning a Super Hero named Tadpole who is part of a group based in New Orleans who has the ability to live underwater (he is a cyborg experiment by an evil Hydra/Viper like group he is running from) who has a tail for swimming, gills to breathe underwater, immune to intense cold/ pressure etc. however while their will be adventures on and in the water, especially the swamp and gulf the bad guys are n more water based than others, so about half and half.

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I am envisioning a Super Hero named Tadpole who is part of a group based in New Orleans who has the ability to live underwater (he is a cyborg experiment by an evil Hydra/Viper like group he is running from) who has a tail for swimming, gills to breathe underwater, immune to intense cold/ pressure etc. however while their will be adventures on and in the water, especially the swamp and gulf the bad guys are n more water based than others, so about half and half.

 

Since he's primarily aquatic, I'd buy the Active Sonar from an underwater perspective and pitch for reduced effectiveness in air. Telescopic (only underwater, probably -1/2 since he'll be using it there a lot) feels about right. Using the rule of thumb that sonar is about four times faster under water than in air, +4 Telescopic works for me (offseting two range doublings). If you feel it should be eight times better, buy it to +6.

 

Don't be concerned about "that makes sonar better than sight!". It doesn't. Sonar will allow targetting and let you know how far away, how large and what it sounds like, but not much else. Sight often doesn't even need to make a detect roll... you can *see* that airliner plunging towards the ground 5,000 metres away, even if it's out of range of your powers and the range mod is too large for you to make a targeting roll. Underwater, sonar should be better than sight. At combat ranges the speed difference between sound and light will not matter in air OR water, even for a SPD12 character, let alone one that takes 2-3 seconds to act.

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