RPG Forums

Go Back   RPG Forums > Role Playing Game Section > Twilight 2000 Forum

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 09-02-2020, 07:04 PM
Vespers War Vespers War is offline
Registered User
 
Join Date: Nov 2018
Posts: 504
Default Varying wood AV by physical qualities

Wood AV is a flat 0.2 per cm, but this overlooks (for the sake of simplicity) that woods have widely varying densities and hardnesses. One of the tests used on wood is the Janka test, which examines how many lb-ft of force it takes to embed a .444" steel ball halfway into a sample of wood. It varies from 380 lbf for Eastern White Pine to around 4-5,000 lbf for Australian Buloke. Buloke is also noted for being as hard as aluminum. I haven't worked this all the way through, but my first idea is that roughly every 500 lbf of Janka hardness might be 0.1 AV per cm, which would give the following examples:

0.1 - white pine, yellow poplar, chestnut
0.2 - red maple, black walnut, cherry
0.3 - hard maple, red pine, zebrawood
0.4 - osage orange, African rosewood, tigerwood
0.5 - live oak, southern chestnut, red mahogany
0.6 - bloodwood, ebony, ironwood

Part of this originates from reading recently about how the USS Constitution's layer of live oak in its hull is thought to be the reason the ship was so hard to penetrate. Near the waterline, it had roughly 12 inches each of white oak and live oak, in a 7-12-5 thickness from outside to inside. This would be AV 12 using the 0.2 AV per cm calculation. Using variable wood, it would be between AV 21 and 24 (white oak is right on the cusp between 0.2 and 0.3). That may not seem like a huge difference when looking at modern artillery, but black powder smoothbores tend to max out penetration at around 10-8-7-5 (it's hard for them to get over the 5 MJ threshold that allows Pen to go up to 28-25-21-13), so at medium range an AV 12 is often penetrated, while either of the higher AVs will see the shot bounce.

Feedback on how to improve the system or other systems for varying the quality of wood are highly welcome, since this is a very rough first draft of an idea.
__________________
The poster formerly known as The Dark

The Vespers War - Ninety years before the Twilight War, there was the Vespers War.
Reply With Quote
  #2  
Old 09-02-2020, 07:47 PM
Wolf sword Wolf sword is offline
Registered User
 
Join Date: Feb 2013
Location: Inver Grove Heights MN
Posts: 48
Default

If you really want to get into the math with this you could also factor in the woods crushing strength rating.
https://www.wood-database.com/wood-a...hing-strength/
The above site also has janka hardness ratings listed on the woods and where the range that the tree grows and all sorts of info, well if you are woodworker.
Reply With Quote
  #3  
Old 09-02-2020, 09:25 PM
Legbreaker's Avatar
Legbreaker Legbreaker is offline
Registered User
 
Join Date: Dec 2008
Location: Tasmania, Australia
Posts: 5,070
Default

Just to muddy the waters a little more, some woods will shatter rather than absorb the impact too. I've noted this is often true of the exceptionally hard woods.
And then there's moisture content to throw in - green/wet wood has more of a dampening effect than seasoned wood.
Not enough factors yet? How about temperature? Sub-zero and you could end up with ice crystals within the fibres and cells making the wood even more brittle than usual.
__________________
If it moves, shoot it, if not push it, if it still doesn't move, use explosives.

Nothing happens in isolation - it's called "the butterfly effect"

Mors ante pudorem
Reply With Quote
  #4  
Old 09-20-2020, 08:13 PM
swaghauler swaghauler is offline
Registered User
 
Join Date: Jan 2015
Location: PA
Posts: 1,481
Default

I'll follow you down the rabbit hole!
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 11:21 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.