Calguns.net  

Home My iTrader Join the NRA Donate to CGSSA Sponsors CGN Google Search
CA Semiauto Ban(AW)ID Flowchart CA Handgun Ban ID Flowchart CA Shotgun Ban ID Flowchart
Go Back   Calguns.net > CALIFORNIA SHOOTING CLUBS AND ORGANIZATIONS > California Precision Rifle Club
Register FAQ Members List Calendar Mark Forums Read

California Precision Rifle Club California Precision Rifle Club Forum

Reply
 
Thread Tools Display Modes
  #1  
Old 04-07-2008, 12:49 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default Rotation of the Earth: Affects on External Ballistics

We've all heard of it now either from the movies or people quoting the movies, but does it really effect external ballistics enough for us to worry about even if we're shooting up to 2000 yds?

Certainly the Coriolis effect comes into play on long range projectiles(traveling many miles), but does it actually effect long range rifle shooting? I mean even assuming you were able to calculate wind and atmospheric conditions perfectly, what is the MAXIMUM influence of the rotation of the earth.

I say MAXIMUM because it will vary depending on which direction you are shooting relative to the earth's axis.
Reply With Quote
  #2  
Old 04-07-2008, 1:30 PM
hoffmang's Avatar
hoffmang hoffmang is offline
No, I am not a Moderator!
 
Join Date: Apr 2006
Location: Peninsula, Bay Area
Posts: 18,494
iTrader: 14 / 100%
Default

You're forgetting about relativity and relative motion. You are in motion from the point of view of someone standing on the moon when you fire regardless of direction fired. The only marginal impact that the earths rotation has on a shot fired in the atmosphere is the movement of the atmosphere being relatively caused by the spin of the earth (windage.)

-Gene
__________________
Gene Hoffman
Chairman, The Calguns Foundation

DONATE NOW
to support the rights of California gun owners. Follow @CalgunsFdn on Twitter.
Opinions posted in this account are my own and not the approved position of any organization.
I read PMs. But, if you need a response, include an email address or email me directly!


"The problem with being a gun rights supporter is that the left hates guns and the right hates rights." -Anon
Reply With Quote
  #3  
Old 04-07-2008, 1:31 PM
Prc329's Avatar
Prc329 Prc329 is offline
Calguns Addict
 
Join Date: Oct 2006
Location: Ramona, CA
Posts: 5,601
iTrader: 40 / 100%
Default

According to Mack on Futureweapons it does
__________________
Reply With Quote
  #4  
Old 04-07-2008, 1:41 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default

Quote:
Originally Posted by hoffmang View Post
You're forgetting about relativity and relative motion. You are in motion from the point of view of someone standing on the moon when you fire regardless of direction fired. The only marginal impact that the earths rotation has on a shot fired in the atmosphere is the movement of the atmosphere being relatively caused by the spin of the earth (windage.)

-Gene
I understand this point. From a stationary point in outer space, the projectile would appear to move in a striaght line, but for a person on the surface the projectile will appear to be moving in a curvalinear motion across the surface (depending on direction). But does this simply translate into wind? Or is there more to it?
Reply With Quote
  #5  
Old 04-07-2008, 1:54 PM
Timberwolf's Avatar
Timberwolf Timberwolf is offline
Calguns Addict
 
Join Date: Oct 2004
Location: Antelope Valley
Posts: 6,301
iTrader: 11 / 100%
Default

At the operative distances of the small arms we use (say 1K or less) there would be very little, if any, impact on POA/POI caused by the Coriolis effect. This normally comes into play (IIRC) at distances exceeding 1200 - 1300 (ergo 338 LM and 408 Chey Tac).

What does effect trajectory and be accounted for normally at distances exceeding 600, in normal 30 cal applications, beyond the normal atmospheric conditions, is compensation for the effects of bullet yaw caused by the rifling twist.

Ever notice how long range shooting is similar to being in the arty . . .
Reply With Quote
  #6  
Old 04-07-2008, 2:09 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default

Don't laugh.. I just learned a ton reading this: http://en.wikipedia.org/wiki/External_ballistics

Now if I could just figure out "how much" these factors actually effect the projectile and i'll be happy.
Reply With Quote
  #7  
Old 04-07-2008, 2:20 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default

Not that I have seen the formula for it, but it looks like the affects can be ROUGHLY calculated by simply knowing the speed the earth rotates at the target and the time it takes for a projectile to reach the target. This will then change depending on the angle you will be shooting at. Sigh.. too much to think about. It's rather quite similar to shooting a moving target.
Reply With Quote
  #8  
Old 04-07-2008, 2:29 PM
hoffmang's Avatar
hoffmang hoffmang is offline
No, I am not a Moderator!
 
Join Date: Apr 2006
Location: Peninsula, Bay Area
Posts: 18,494
iTrader: 14 / 100%
Default

Varying gravity due to core density of the earth above which the projectile flies is going to have more (and harder to calculate) effects on the shot than any other motion past wind.

-Gene
__________________
Gene Hoffman
Chairman, The Calguns Foundation

DONATE NOW
to support the rights of California gun owners. Follow @CalgunsFdn on Twitter.
Opinions posted in this account are my own and not the approved position of any organization.
I read PMs. But, if you need a response, include an email address or email me directly!


"The problem with being a gun rights supporter is that the left hates guns and the right hates rights." -Anon
Reply With Quote
  #9  
Old 04-07-2008, 3:12 PM
Vu 308's Avatar
Vu 308 Vu 308 is offline
Senior Member
 
Join Date: Oct 2007
Location: Nor Cal
Posts: 2,380
iTrader: 12 / 100%
Default

Ask marky Mark.
Reply With Quote
  #10  
Old 04-07-2008, 3:15 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default

Quote:
Originally Posted by Vu 308 View Post
Ask marky Mark.
Sadly, that's the first time I heard of it. Then i started hearing other people quote it and decided to do some fact checking. To top it off, my girlfriend told me about the "Coriolis" effect as I was talking about it even though I'm the one with the physics background. It has been an embarassing journey..
Reply With Quote
  #11  
Old 04-07-2008, 3:18 PM
EastBayRidge's Avatar
EastBayRidge EastBayRidge is offline
Member
 
Join Date: Apr 2007
Location: East Bay, CA
Posts: 478
iTrader: 0 / 0%
Default

Snipers Hide had longish threads on the topic here and here.
__________________
Leave the cannoli, take the gun.



Jest tylko ziemia. Jedna ziemia i pory roku nad nią są.

ΜΟΛΩΝ ΛΑΒΕ
Reply With Quote
  #12  
Old 04-07-2008, 3:24 PM
rksimple's Avatar
rksimple rksimple is offline
Calguns Addict
 
Join Date: Jan 2006
Location: T-Town
Posts: 6,218
iTrader: 11 / 100%
Default

The SH threads were good. Some funny stuff in there.
Reply With Quote
  #13  
Old 04-07-2008, 3:31 PM
wildcard's Avatar
wildcard wildcard is offline
Veteran Member
 
Join Date: Aug 2006
Location: Arcadia, CA
Posts: 4,914
iTrader: 11 / 100%
Default

Quote:
Originally Posted by EastBayRidge View Post
Snipers Hide had longish threads on the topic here and here.
I just read through the threads and there is one thing that everyone seems to be forgetting, even though the effect is maximized when shooting N and S, the further you are from the equator, the less the effect is going to be. In fact, if your targets were at the north and south poles (the ends of the axis), there would be no coriolis effect because the targets would be stationary (though rotating).

Or maybe i'm wrong?
Reply With Quote
  #14  
Old 04-07-2008, 3:35 PM
Prc329's Avatar
Prc329 Prc329 is offline
Calguns Addict
 
Join Date: Oct 2006
Location: Ramona, CA
Posts: 5,601
iTrader: 40 / 100%
Default

I was just messing around with the Mack comment. I do believe it is something that most of us will never encounter. It is hard enough to shoot 1000 yards in CA. Shooting long enough to see the Coriolis effect is banned by name.
__________________
Reply With Quote
  #15  
Old 04-07-2008, 4:57 PM
PistolPete75's Avatar
PistolPete75 PistolPete75 is offline
Calguns Addict
 
Join Date: Jan 2007
Location: Los Angeles
Posts: 5,223
iTrader: 44 / 100%
Default

didn't this come out of the movie shooters with marky mark?
Reply With Quote
  #16  
Old 04-07-2008, 6:14 PM
Vu 308's Avatar
Vu 308 Vu 308 is offline
Senior Member
 
Join Date: Oct 2007
Location: Nor Cal
Posts: 2,380
iTrader: 12 / 100%
Default

No....the movie just made it more known.

This type of thing only matters at EXTREME long ranges in my opinion.

The wind and other factors will kick ur arse before this will.

Got my arse handed to me this weekend by the wind...doubt the rotation of the earth did much at 1K to me. LOL
Reply With Quote
  #17  
Old 04-07-2008, 9:02 PM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 39,084
iTrader: 88 / 100%
Default

Quote:
Originally Posted by Prc329 View Post
According to Mack on Futureweapons it does
<whisper>be vewy vewy quiet, I'm hunting wabbits at 1600yds with this 416 barrett.</whisper>
__________________
Randall Rausch

AR work: www.ar15barrels.com
Bolt actions: www.700barrels.com
Foreign Semi Autos: www.akbarrels.com
Glock, XD and M&P pistols, Benelli and Remington shotguns: barrel, sight, trigger and receiver work.
Most work performed while-you-wait, evening and weekend appointments available.
Founding member of the CAPRC
Reply With Quote
Reply

Thread Tools
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 -8. The time now is 7:57 AM.




Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Proudly hosted by GeoVario the Premier 2A host.
Calguns.net, the 'Calguns' name and all associated variants and logos are ® Trademark and © Copyright 2002-2016, Calguns.net an Incorporated Company All Rights Reserved.