Underwater DPW Formula

[nuke11]

Has anyone come up with a modification to DPW as it travels thru water?

I found this: https://apps.dtic.mil/sti/pdfs/ADA527409.pdf and this https://ia904707.us.archive.org/6/items/handbookofnavalc00unit/handbookofnavalc00unit.pdf

I was thinking about dropped hand grenades in pools, ponds that sort of thing.

[mmartin798]

While I never really considered it, I know the concussive wave will travel different in a denser medium than air. Though there is the fact air is less dense than water, so the total energy loss over distance should also be less.

Not being one to shy away from a good read of highly technical material to get a game play result out of it, I will take a look and see what I can make of it all.

[nuke11]

Here are some more papers I found;

https://www.researchgate.net/publication/251393757_Underwater_Explosion_Phenomena_and_Shock _Physics

https://libjournals.unca.edu/ncur/wp-content/uploads/2021/03/2696-Austin-John-FINAL.pdf

https://ffi-publikasjoner.archive.knowledgearc.net/bitstream/handle/20.500.12242/3092/22-02062.pdf

https://apps.dtic.mil/sti/tr/pdf/ADA352831.pdf

https://www.researchgate.net/publication/266606168_Calculating_the_Effect_of_Surface_or_Und erwater_Explosions_on_Submerged_Equipment_and_Stru ctures

https://www.researchgate.net/publication/305760969_Modeling_the_Effect_of_Underwater_Explos ion_on_a_Submerged_Plate_Structure

https://books.google.ca/books?hl=en&lr=&id=c3mfEAAAQBAJ&oi=fnd&pg=PA301&dq=Modeling+the+Effects+of+Underwater+Explosions+o n+Submerged+Structures&ots=6mEJkqn1dJ&sig=CCJJKtuvMc4K6m00MmB5Oa7SpBk#v=onepage&q=Modeling%20the%20Effects%20of%20Underwater%20Exp losions%20on%20Submerged%20Structures&f=false

https://www.mdpi.com/2076-3417/7/9/880

[mmartin798]

I did some looking and this is a non-trivial problem with no simple model that is able to predict outcomes. Most models are computationally derived and are difficult to make into a game mechanic.

That being said, I did find an article in the National Medical Library which is part of the National Institute on Health which looked at outcomes from various recorded underwater explosions. While the entire article looks at many different aspects of this, including evaluating protective measures advocated over the years, there was one chart that I think can be the basis of some underwater explosion rules. The article can be found here (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4659630/).

Figures 3 through 6 nicely combine and simplify the dataset used and can probably be the genesis of a convenient rule for DWP underwater. If you want the actual data set, you can download it as well from a link towards the end of the article. I will try and build a simplified rule set for underwater explosions in the next few days if my schedule stays relatively open.

[mmartin798]

I do want to get an opinion. We need to establish what amounts of DPW would constitute a 10% and 50% risk of injury and also what amount yields 10% fatality rates and 50% fatality rates.

[nuke11]

I do want to get an opinion. We need to establish what amounts of DPW would constitute a 10% and 50% risk of injury and also what amount yields 10% fatality rates and 50% fatality rates.

Here is some information I found while researching the Mk80 125lb GPLD Bomb. I researched the Mk80, 81 and 82 for an Aircraft supplement I have been working on and off for a number of years.

This might help establish a baseline.

E-FACTOR: 35, 14 average fragment (3 to 300 grains)
DPW: 41,979
BLAST RADIUS;
Lethal: approximately 15.00 m (10 psi, 100% Mortality)
Effective: approximately 30.00 m (3.5 psi, 50% Mortality)

[mmartin798]

Do you happen to know the weight of the explosive in the Mk80 125lb GPLD Bomb? I can't find a Mk 80 series bomb at the 125lb point. I can assume approx 60lb. I can pop it into my spreadsheet and get a damage vs distance plot for air. Then I think I can use the curves from the papers to come up with something more general for underwater.

[nuke11]

Do you happen to know the weight of the explosive in the Mk80 125lb GPLD Bomb? I can't find a Mk 80 series bomb at the 125lb point. I can assume approx 60lb. I can pop it into my spreadsheet and get a damage vs distance plot for air. Then I think I can use the curves from the papers to come up with something more general for underwater.
Sorry for the delay.

Depending on the filler.

18 Kg Composition H6
20 Kg TNT

What you are looking for is from central america. Columbia produces a 125 lbs GP bomb I used. I figured if the US did produce one it would be very similar to this one. The name came from an extrapolation of the family.

https://indumilweb.dugalu.com/producto/bomba-imc-xue-125-lb-pg/
https://publicacionesdigitalessite.wordpress.com/wp-content/uploads/2017/09/8c13b-bombasindumil.png?w=840

[mmartin798]

Just a quick update as to where I am in the process and the future direction. Using the data I have, I have a very nice looking curve of survivability versus range with a 10Kg TNT blast. But it is not proving to be easily converting fatality percentage to damage.

I have the paper from the Plos One, so I think I will be able to make aa couple injury versus range plots and then pick some values for points where you are definitely dead and one for barely injured. The rest should fall in and then I can look to see if there is an "easy" scaling to be done between air and water explosions.