theory long shot

Discussions on high/extreme altitude and mach busting rockets.

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mulga metal
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theory long shot

Postby mulga metal » Wed Aug 09, 2017 6:22 pm

Not knowing much engineering but enough to get confused , I tried analysing forces of a sharp blade on solids . For advice I tried a boat hydro dynamics forum , Yank Physics forums , UK Forensic forum and Oz Archaeology forum . Apart from the Yanks who can't read plain English , the others don't know nothing . Oz Wood Research don't know and everyone at universities doesn't know what happens to bone under stress . The Bulk Modulus of bone and hardwoods are similar.They say air at Mach becomes like water which is maybe similar as trabecular bone has about 40% fluid marrow .

So what happens to a projectile rocket when it yaws off-centre and moves obliquely? How does resistance vary with angle as it approaches 90degrees ? The purpose is to find the difference between a blunt 10mm thick boomerang and an Indonesian sword striking a skull . More info will follow if anyone has the time to spare / waste .

Catalyst: Toorale Man murder mystery - ABC TV Science
http://www.abc.net.au/catalyst/stories/4211835.htm
Apr 7, 2015 - ....Bizarrely the wounds on Toorale Man appear similar to those on gladiators in Imperial Rome.

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SpaceManMat
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Re: theory long shot

Postby SpaceManMat » Wed Aug 09, 2017 9:18 pm

Hmm.. Sounds like an experiment out of myth busters or CSI involving pig carcasses may be in order...
But not sure about the skull bit, think a pigs will be harder.
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SpaceManMat
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Re: theory long shot

Postby SpaceManMat » Wed Aug 09, 2017 10:07 pm

Having watched the documentary a few thoughts come to mind. The historical naritive that aboriginals lived in Australia for thousands of years in isolation is overly simplistic. If they could get here then certainly others could too. For instance we know northern Australia was visited and traded with people from Indonesia and New Guinea, we also know that there was some contact with Europeans along the WA coast, think Batavia. Now I'm not sure of the exact timing of these but it's irrelevant, there is no reason why contact, trading etc could not happen earlier it's just that there is no remaining record of it. Or what evidence there is has been misinterpreted or attributed to later events.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

mulga metal
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Re: theory long shot

Postby mulga metal » Thu Aug 10, 2017 5:44 am

Right on , data from Mythbusters and ceiling fans on pig , radiology of skull trauma and uni tests of mulga on pig skull give some evidence . Here are graphs of cutting force and normal perpendicular force at high angle of chisel in wood.
Resistance drag is sine frontal area and forces may be tan of tool angle . Does any of that ring a bell?

https://bioresources.cnr.ncsu.edu//BioR ... d_1402.pdf

page 3698 .

Canadian ice hockey puck of .16kg at about 47 metres /sec is a headache.
Mark Fraser Injury: Skull Purportedly Shows Impact Of Puck
http://www.huffingtonpost.ca/2013/05/13 ... 68980.html

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Re: theory long shot

Postby mulga metal » Thu Aug 10, 2017 6:06 am

Mulga- wood boomerang blades are about 5-10mm thick at 10mm back from edge at 30-60 degrees where a sword is 3mm. The wood is bi-convex and needs a clearance angle next to the wood to allow cutting by the sharp edge. This rough sketch needs to adjust to the angles given with the bi-convex tip adding about 20degrees either side at contact.
The thickest blades are perpendicular at leading edge contact or maximum possible resistance .



I /cutting angle , rake 15 degrees
I /
I /
I / / / cross-section of blade, tool angle. Skull is cut at about 45 degrees.
/ /
/ /
/ /
/ /
/ /
' /
\ ,
Bi-convex curve \ < 5-10mm> ,
\ ,
\ ,
\ ,
75 degrees \ , ) clearance angle 5 degrees
----------------------------------v ----------------------------------------------------
^ ____________cortex bone
-_
8mm - _ trabecular marrow
skull cortical bone v __-___________________
-----------------------------------------------------------------------

mulga metal
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Re: theory long shot

Postby mulga metal » Thu Aug 10, 2017 6:09 am

aaaargh
no edit.
anyway imagine a chisel drawn as / shaped like the small end of an egg with a point .

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Re: theory long shot

Postby mulga metal » Thu Aug 10, 2017 1:59 pm

The web address above is no good , should be :

https://bioresources.cnr.ncsu.edu//BioR ... d_1402.pdf

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Re: theory long shot

Postby mulga metal » Thu Aug 10, 2017 2:01 pm

https
://bioresources.cnr.nscu.edu//BioRes_06_4_3687_Porankiewicz_AGM_Main_Norm_Cut_Forces_Wood_1402.pdf.


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