[trip286]

Thread went from this...

Originally Posted by Vincine

This is from another forum and concerns .22lr long range shooting. What do you guys here know about this? So the rotational speed of a bullet interacting with a side wind has a larger effect on its trajectory than the amount of time a bullet is subjected to the side wind??

Higher speed bullets have a flatter trajectory than lower speed bullets. Under 'No Wind' conditions, the higher speed bullet will be more 'accurate'. That is, it requires less adjustment of POA than a slower speed bullet.

This implies that there is a wind speed/bullet fps crossover point at which the flatter trajectory of the higher speed bullet is negated by the effect of a side wind. Right?

To this.

Originally Posted by Eturnsdale

Hold on a sec. <looks in her pants> Yup an inny.

I enjoyed our chat as well.

Just one of the reasons I love this forum!

[Intheshop]

The one son thats still living at home(moving out after huntin season,which is rediculously funny........he's going to miss home cooking AND Deer whackin)


He graduated first team accademics with a dble major....Math and Physics.His answer was "beats me".Well,it was a little more involved....something about models and parameters in physics being pulled out of ones arse,or some such.IOWs,you can change a cpl things and sort of swing results in different ways....all brain numbing.

I'm only slightly more interested.I like to know a few terms and relationships....but like #3 son above,can pretty much throw wrenches in the discussion at will.And not for reasons of argument...more to show how little things can skew results.One for instance is most folks take for granted a projectile has "perfect" balance........uhhh,they don't.Its like a "straight" arrow.Straight to what degree?Just sayin....I'm more of a test it and see if you can get things clear in "your" mind.

I will say....from shooting tournament archery that a "bent" arrow.....(and "how bent" affects this)....will and does "go to sleep" at some point in its rate of rotation and velocity.The more bent,the longer(translates to slower)it takes on the flight path,to go to sleep.

[Vincine]

Originally Posted by Intheshop

. . . . .I will say....from shooting tournament archery that a "bent" arrow.....(and "how bent" affects this)....will and does "go to sleep" at some point in its rate of rotation and velocity.The more bent,the longer(translates to slower)it takes on the flight path,to go to sleep.

Please do continue. Tell us all about how the degree of flex in the shaft, affects the 'archer's paradox'. I promise I won't go to sleep.

[Eturnsdale]

Originally Posted by Vincine

I don't know that that's what we all were saying, but what you're saying sounds right.

I was saying exactly what TCH2FLY said, but in what I thought were much more simple terms.

Originally Posted by TCH2FLY

The RPM (revolutions per minute) of the round will increase with velocity using a given twist.

muzzle velocity fps x (12/twist rate in inches) x 60 = rpm of bullet
1020fps x (12/16) x 60 = 45900 rpm
1270fps x (12/16) x 60 = 57150 rpm

Originally Posted by trip286

Thread went from this...



To this.



Just one of the reasons I love this forum!

It happens so naturally sometimes.

[Vincine]

Originally Posted by Eturnsdale

I was saying exactly what TCH2FLY said, but in what I thought were much more simple terms. . . .

Initially I was asking about the effect on a bullet when the wind flows over the top of the bullet in the same direction of the its spin vs. when it flows over the top of a bullet in the opposite direction of its spin. I forget which causes lift and which causes drop. Apparently it’s NOT called the Magus Effect. This is a separate issue from wind drift and transonic issues which would occur in either case. But then thread explored other ballistic (& non-ballistic ) issues as well, which is okay with me.

[Flat Tire]

Originally Posted by pranc2

the speed of sound is a majority of the time well above 1080fps it is only that low with high altitude and or cold weather because the air is thinner. at sea level and 70 degrees F the speed of sound is around 1165 fps. the trans-sonic flight is affect more in a .22 because of more drag or ballistic coefficient ( someone did say that) and the mass. A .308 weighs at least 4 times as much and streamed lined. Even in trans-sonic flight the .308 is more predicable.

I live at 6300' above sea level

[Vincine]

SoS @ 6300' = 1034.5 fps @ 45F

http://www.engineeringtoolbox.com/elevation-speed-sound-air-d_1534.html

[Eturnsdale]

Originally Posted by Vincine

Initially I was asking about the effect on a bullet when the wind flows over the top of the bullet in the same direction of the its spin vs. when it flows over the top of a bullet in the opposite direction of its spin. I forget which causes lift and which causes drop. Apparently it’s NOT called the Magus Effect. This is a separate issue from wind drift and transonic issues which would occur in either case. But then thread explored other ballistic (& non-ballistic ) issues as well, which is okay with me.

Yeah, if you ask five people you will get six different answers. Though from most of the physics folks Ive talked to say there isn't any lift from air transfer over or under a spinning projectile unless it is completely spherical.

But then again to see that a bullets shape will alter it's drop all you have to do is look at two different bullets, of the same weight fired at the same velocity to see this.

Maybe I am getting off track again.

[partdeux]

Originally Posted by Intheshop

I will say....from shooting tournament archery that a "bent" arrow.....(and "how bent" affects this)....will and does "go to sleep" at some point in its rate of rotation and velocity.The more bent,the longer(translates to slower)it takes on the flight path,to go to sleep.

Anybody else think of LaMont from revenge of the nerds?

[vincent]

Originally Posted by partdeux

Anybody else think of LaMont from revenge of the nerds?

Now I did...and his limp wristed throwing style!!!