Where can I find the magnus effect chart that Speedy recommends for shot placement. Or I guess you could call it a wind drift chart. Thank you
Speedys magnus effect chart
- Thread starter clean hands
- Start date
If/when you employ this info, it's important to visualize that, "from the cross-hair", this chart presumes a dead-center, dead-calm ZERO!
Let's pretend I'm ZEROed in a 2:00 O'clock wind- the bullet impacts exactly on the cross-hair intersection: all other vectors then impact relative to THAT ZERO - not the points displayed on the chart(s)!
This stuff does work - I use it all the time, when I must make a SWAG to keep a shot on the X, or, at least, in the ten-ring!
The bullets impact relative to the ZERO condition, and also, in a rare constant vector (angle), move more, or, less as wind velocity varies. Different variations of this chart accommodate differing visualization aptitudes. One of my rather crafty pupils made a nice plastic over-lay, and picked up on this quite quickly. Keep 'em ON the X! RG
Last edited:
Perfect point, Randy.
Here's the one I like/use religiously.
I use the "mirage" pointer to remind me of the ZERO vector. RG
I use the "mirage" pointer to remind me of the ZERO vector. RG
Was that a Dunrud product, Randy?
butchlambert
Site $$ Sponsor
It ain't Mr. Gonzales's deal.
Butch is correct - these were made by a gentleman, from Colorado - I am embarrassed that I cannot recall his name. I've had mine since the mid-1990's; they were branded SHOOTING STAR. I believe they have been out of production for about ten years already - anyone know for certain? I've subjected mine to some abusive hauling the last couple of years, and the wear is showing . . .
Several of my peers simply print the star, laminate it, and keep it close by when shooting. RG
BountyHunter
Gold $$ Contributor
email comes back undeliverable!
I googled
Benchrest.com/shotstar and found it but now the guys on BR Central say the man died and it's no longer available.
Benchrest.com/shotstar and found it but now the guys on BR Central say the man died and it's no longer available.
I have heard that magnus effect affects smallbore bullets but have yet to see it for centerfire rifle.
Just for clarity, this chart has nothing to do with the Magnus Effect. It's a wind 'drift' chart showing the vertical effect of crosswind on drag. Crosswind components simply re-direct some of the base drag upward or downward.......the bullet is not "rolling on the air" as implied by the usage of the term Magnus Effect.
af
Don't agree. Look at the chart: if the wind is coming from 7 o'clock, the bullet is pushed to the right and DOWN. If it was a pure wind drag effect it would be pushed right and UP.
.
Fast14riot
Gold $$ Contributor
Is this dependant on a right hand twist?
The vertical component is due to precession - the free spinning bullet is a gyro, thus, it tries to avoid the applied force (drag) in the direction of its spin, perpendicular to the force. Most barrels, are right hand twist, a left hand twist will reverse the star. Left hand winds (7;8;9;10;11;12:00 O'clock) work in conjunction with gravity, thus vertical associated with 'drift' is usually greater than observed when the vector is from the right (1;2;3;4;5;6:00 O'clock), where the bullet 'wants' to move opposite gravity. Keep 'em ON the X! RG
pat fulghum
( ͡° ͜ʖ ͡°)
Very interesting....
Comparing the relative shift of a change from 12 to 1 as compared to a shift from 5 to 6 is not intuitive.
Comparing the relative shift of a change from 12 to 1 as compared to a shift from 5 to 6 is not intuitive.
I don't remember exactly the effect of precession, but I don't think precession results in linear displacement but in added rotation about another axis other than the bullet's axis.
I take it that will be with a rite twist barrel?
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.