Wind V Air Pellets V Rimfire Bullets

Bill Collaros

Bill Collaros

Shoot to Thrill
A question that has come up Down Here, that maybe our more experienced US Air Friends could answer.

Do Air Pellets get affected the same way and direction as Rimfire Bullets by Wind ?

EG: In Rimfire, Wind right to left will see the bullet go left and and up & Wind left to right will see the bullet go right and low.
 
The up/down component is caused by the extra friction between the spinning projectile and the air. In my experience, and since the pellets in most air rifles rotate at similar rates relative to their forward velocity to that of rimfire bullets, they are affected in the same way.

Edit: This appears to be inaccurate. Ignore.
 
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Quartering winds from the rear cause some strange shifts for me that don't jive with the rimfire wind clock. Anyone else see this? Headwinds are a bit better but still not like rimfire. The up/down component seems very erratic.
 
Go to the Yellow forum and do a search for vidios of pellet flight, Done by one of your compadres over there in Aussy land. I think his first name is Harry. some are slow motion so you can see the spiraling of the projectile which is quite a bit different than RF.
 
The spiraling is seen when there are problems and are not the norm. When everything is working correctly a pellet does not spiral. If the pellet is spiraling then reading the wind is irrelevant. One must first stop the spiraling.
 
blades said:
Go to the Yellow forum and do a search for vidios of pellet flight, Done by one of your compadres over there in Aussy land. I think his first name is Harry. some are slow motion so you can see the spiraling of the projectile which is quite a bit different than RF.
Click to expand...

Thus the question, Dan/Todd any thoughts ?

I am testing but the jury is still out.
 
If there is any alteration to normal dialling for range shooting at an air rifle may with left to right wind increase diagonally usually 45 degrees. Same applies but opposite when right to left wind is applied but very rare maybe 2 times per year shot weekly.
 
Bill,
I agree with SciGuy- Quartering winds from the rear cause some strange shifts for me that don't jive with the rimfire wind clock. Anyone else see this? Headwinds are a bit better but still not like rimfire. The up/down component seems very erratic. And JonnyH if I understand correctly what he's saying-less elevation shift from right to left than left to rigth?
The hardest thing to learn for me when I switched from RF BR to AR after 9 yrs was the difference in the way pellets act in the wind, and the fact that a minor quartering change has much more effect on elevation than it does with a bullet.
Todd
 
The effect is called aerodynamic jump. Let us assume a left to right wind that is consistent between the shooter and target and a right hand rifling twist. When the pellet is fired and leaves the barrel it is pointing along the line of sight. The air it is traveling through is moving across its line of sight. The pellet wants to travel nose forward. If there were no wind it would be flying nose forward relative to the ambient air. Since the air is moving to the right the pellet must yaw to the left to be nose forward in the wind. Since the pellet is spinning the act of yawing to the left causes the pellet to pitch upward due to gyroscopic precession.
Gyroscopes have a funny reaction to a force applied, they want to turn 90 degrees to that applied force. Pellets do the same since they spin. This upward pitch causes the pellet to lift slightly. The lifting action only happens while the pellet is steering into the wind which is why with long range shots the effect of aerodynamic jump is less obvious. The pellet only yaws for a short distance, assuming a constant even wind. The effects are reversed when the wind is to the left, the pellet hits low. If the rifling is left hand the effect will be opposite right hand twist.
Pellets react opposite bullets with respect to aerodynamic jump. The reason is because a pellet's center of gravity is forward of its center of form.
I have noticed some pellets, e.g. exact express, do not exhibit AJ. I guess because the CG is balanced with the center of form.
One of the reasons I've been experimenting with slow twist barrels is to minimize the effects of aerodynamic jump.
Dan
 
You are the Bill Calfee of the Air Rifle World Dan :cool:

I will continue testing to convince my own mind which is 3/4 of the battle.
 
Not exactly, left to right wind will do either of two things, stay the same height or increase up to a 45 degree angle at target.
Right to left will either see no change or a drop right to left up to 45 degrees at target.
Thats from actually shooting, its a rarity perhaps three shoots a year all year round whether -6 or 100+ degrees.
 
Up or down with winds from left or right.

I almost never hold windage only I most always add elevation up or down. What kills my score if I am holding for a left wind at a moderate velocity and the wind drops without a direction change I go out in the direction of the wind.

Logical I guess but sure ruins some scores.

Bob Z
 
BobZ holding off or adjusting do the same thing but in different ways, you are correct though i think when the wind dies and you have clicked or held off you are in no mans land.

What i am trying to ascertain is thoughts on what the wind does do these little pellets, i think Johnyh has summed up what i was told by Harry Fuller and what i am finding in simple terms.
 
Bill Collaros said:
A question that has come up Down Here, that maybe our more experienced US Air Friends could answer.

Do Air Pellets get affected the same way and direction as Rimfire Bullets by Wind ?

EG: In Rimfire, Wind right to left will see the bullet go left and and up & Wind left to right will see the bullet go right and low.
Click to expand...

Bill and others interested:

In 2010 I carried out this project to compare the vertical dispersion resulting from "waisted" diabolo pellets with that of "bullet-like" pellets. This had grown out of an ongoing discussion with Don Matzeder since 2004 and the repeated experience I had of diabolo pellets seeming to react differently to RF bullets.

Note the obvious difference in the slopes of the two groups' shot in the same 9:00 oclock (see flags) wind; the degree of right displacement upward or downward depending upon the wind strength.

Note also in the ensuing discussion the excellent explanation given by Ron Burnett (echoed here by Dan above).

The rifle was sighted in for the heavier "bullet-like" Monster Stratons; hence the higher impacts of the lighter, faster JSB diabolos.

http://www.network54.com/Forum/7953...t++group+pics+for+Don+Matzeder+and+others+---

My SM videos of spiral/ helical flight of pellets is not relevant to this discussion. As is pointed out by SciGuy here, that phenomenon is a separate issue.

Best regards, Harry.
 
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See you next week Harry, Sydney International Shooting Centre should put up some good strong 3 Oclock winds we can play with, I imagine you have that TM1000 humming by now :)
 
Bill Collaros said:
See you next week Harry, Sydney International Shooting Centre should put up some good strong 3 Oclock winds we can play with, I imagine you have that TM1000 humming by now :)
Click to expand...

Looking forward to it Bill. Bring on the dreaded wind!
Have caught Dan's disease. Preferred pellet at sub 12 fpe : 7.9 gr JSBs Lewis sent me; 2006 vintage but the few in the old tin have just about run out! Not to worry, second best 8.4 gr are doing OK. With Dan's and others' advice, I have the regulator working for sub 12 fpe to march in step with the Holy EV 11s.

Getting a .22RF rifle may be a problem for that event. ... See you there. Best regards, Harry.
 
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