# Reply To: Is faster always better in the wind? New slug info page3

Forums › Pellets, Projectiles, Slugs, & Ammo › Is faster always better in the wind? New slug info page3 › Reply To: Is faster always better in the wind? New slug info page3

Thanks @edosan. Remember, we are not talking accuracy or precision here, just wind influence as related to pellet speed and BC. Perhaps your guns are more accurate at the higher speeds (1000 FPS?), and that outweighs any performance benefits of 950 FPS and less with regards to wind deflection. My assumption is/was that most guns (other than ST barrels) are pretty much just as accurate at 850 as at 950, so in that instance anywhere in that band is fine. I know for a fact that my old .30 Bobcat Mk2 shooting JSB Exact 44.8 grain pellets at 880 FPS is just as accurate as any gun I have shot or have seen at EBR or RMAC… Now if I could only shoot as good as you, or Alvaro, or Claudio… Its interesting just how often our "instincts" are totally wrong…

The MATH:

The math behind the physics, for all you nerds and geeks like me that like to see "proof" of this… What this basically proves mathematically is that the "lag time", who major influence is a pellet's BC is the significant influence on the amount of wind drift.

Its called Didion's Equation, shown at the bottom.

Didion's Approximation is called the "Delay Lag Theory" as explained in the Hard Air Magazine article quotes above. Given only the Drag coefficient and pellet dimensions, Deflection cannot directly be calculated. However, if the actual Flight time can be measured or calculated, then to calculate the Wind deflection is quite simple.

The term (t-sy/v0) is the difference between Flight time in Vacuum and actual Flight time, or the "Lag" time.

Didion's Equation derivation link

lateral Wind |

the Didion Equation |

- This reply was modified 4 months ago by Centercut.

Thanks @edosan. Remember, we are not talking accuracy or precision here, just wind influence as related to pellet speed and BC. Perhaps your guns are more accurate at the higher speeds (1000 FPS?), and that outweighs any performance benefits of 950 FPS and less with regards to wind deflection. My assumption is/was that most guns (other than ST barrels) are pretty much just as accurate at 850 as at 950, so in that instance anywhere in that band is fine. I know for a fact that my old .30 Bobcat Mk2 shooting JSB Exact 44.8 grain pellets at 880 FPS is just as accurate as any gun I have shot or have seen at EBR or RMAC... Now if I could only shoot as good as you, or Alvaro, or Claudio... ;) Its interesting just how often our "instincts" are totally wrong...

The MATH:

The math behind the physics, for all you nerds and geeks like me that like to see "proof" of this... What this basically proves mathematically is that the "lag time", who major influence is a pellet's BC is the significant influence on the amount of wind drift.

Its called Didion's Equation, shown at the bottom.

Didion's Approximation is called the "Delay Lag Theory" as explained in the Hard Air Magazine article quotes above. Given only the Drag coefficient and pellet dimensions, Deflection cannot directly be calculated. However, if the actual Flight time can be measured or calculated, then to calculate the Wind deflection is quite simple.

The term (t-sy/v0) is the difference between Flight time in Vacuum and actual Flight time, or the "Lag" time.

Didion's Equation derivation link

lateral Wind |

the Didion Equation |