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I know a few of us have seen this document, but I know a lot of others have not. This is basically a big research project done (by someone else, not myself) to describe the physics of an airsoft BB. Almost anything you want to know about a BB being shot will be in this link: http://mackila.com/airsoft/atp/
Content:
I. Physics Principles and Equations
A. Physical Characteristics of BB's, Pellets, Paintballs, Etc.
1. Diameter
2. Volume / Density and Terminal Velocity
B. Air Density
C. Kinetic Energy
D. Forces Governing Trajectory
1. Drag Force
2. Velocity
3. Distance
4. Magnus Force
5. Terminal Velocity
6. Spin Decay
7. Drag Coefficient
8. Lift Coefficient
9. Gravity
II. Testing and Model Validation
A. Verifying Velocity Calculations
III. Effects of Hop-Up
IV. Effective and Maximum Range for 6mm BB's
A. Definitions of Effective and Maximum Range
B. Effective Range and Recommended BB Weight
C. Effective Range Observations
V. Environmental Effects
A. Effect of Wind on Trajectory
1. Headwind / Tailwind Component
2. Crosswind Component
B. Effect of Altitude on Trajectory
C. Effect of Temperature on Trajectory
VI. Minimum Engagement Distance
A. Determining Muzzle Energy
B. Safe Impact Energy
C. Recommended Universal MED's
VII. Modeled Data
A. Velocity Comparisons Using BB's of Equal Masses
1. Velocity Comparison Using 0.20 Gram BB's
2. Velocity Comparison Using 0.25 Gram BB's
3. Velocity Comparison Using 0.28 Gram BB's
4. Velocity Comparison Using 0.29 Gram BB's
5. Velocity Comparison Using 0.30 Gram BB's
6. Velocity Comparison Using 0.36 Gram BB's
7. Velocity Comparison Using 0.43 Gram BB's
8. Velocity Comparison Using 0.88 Gram BB's
9. Velocity Comparison Using 0.34 Gram 8mm BB's
10. Velocity Comparison Using 0.45 Gram 8mm BB's
B. Mass Comparisons of Projectiles Fired at Equal Energies
1. Effects of Different BB Masses Fired at 0.37 Joules (200 fps Using 0.20g)
2. Effects of Different BB Masses Fired at 0.47 Joules (225 fps Using 0.20g)
3. Effects of Different BB Masses Fired at 0.58 Joules (250 fps Using 0.20g)
4. Effects of Different BB Masses Fired at 0.70 Joules (275 fps Using 0.20g)
5. Effects of Different BB Masses Fired at 0.84 Joules (300 fps Using 0.20g)
6. Effects of Different BB Masses Fired at 0.98 Joules (325 fps Using 0.20g)
7. Effects of Different BB Masses Fired at 1.14 Joules (350 fps Using 0.20g)
8. Effects of Different BB Masses Fired at 1.49 Joules (400 fps Using 0.20g)
9. Effects of Different BB Masses Fired at 1.88 Joules (450 fps Using 0.20g)
10. Effects of Different BB Masses Fired at 2.32 Joules (500 fps Using 0.20g)
11. Effects of Different BB Masses Fired at 2.81 Joules (550 fps Using 0.20g)
12. Effects of Different BB Masses Fired at 3.35 Joules (600 fps Using 0.20g)
13. Effects of Different BB Masses Fired at 3.93 Joules (650 fps Using 0.20g)
14. Effects of Different BB Masses Fired at 4.55 Joules (700 fps Using 0.20g)
VIII. Closing Remarks
IX. References
X. Online Calculators
A. MilDot Scope Calculator
B. Relative Energy / Minimum Engagement Distance Calculator
Content:
I. Physics Principles and Equations
A. Physical Characteristics of BB's, Pellets, Paintballs, Etc.
1. Diameter
2. Volume / Density and Terminal Velocity
B. Air Density
C. Kinetic Energy
D. Forces Governing Trajectory
1. Drag Force
2. Velocity
3. Distance
4. Magnus Force
5. Terminal Velocity
6. Spin Decay
7. Drag Coefficient
8. Lift Coefficient
9. Gravity
II. Testing and Model Validation
A. Verifying Velocity Calculations
III. Effects of Hop-Up
IV. Effective and Maximum Range for 6mm BB's
A. Definitions of Effective and Maximum Range
B. Effective Range and Recommended BB Weight
C. Effective Range Observations
V. Environmental Effects
A. Effect of Wind on Trajectory
1. Headwind / Tailwind Component
2. Crosswind Component
B. Effect of Altitude on Trajectory
C. Effect of Temperature on Trajectory
VI. Minimum Engagement Distance
A. Determining Muzzle Energy
B. Safe Impact Energy
C. Recommended Universal MED's
VII. Modeled Data
A. Velocity Comparisons Using BB's of Equal Masses
1. Velocity Comparison Using 0.20 Gram BB's
2. Velocity Comparison Using 0.25 Gram BB's
3. Velocity Comparison Using 0.28 Gram BB's
4. Velocity Comparison Using 0.29 Gram BB's
5. Velocity Comparison Using 0.30 Gram BB's
6. Velocity Comparison Using 0.36 Gram BB's
7. Velocity Comparison Using 0.43 Gram BB's
8. Velocity Comparison Using 0.88 Gram BB's
9. Velocity Comparison Using 0.34 Gram 8mm BB's
10. Velocity Comparison Using 0.45 Gram 8mm BB's
B. Mass Comparisons of Projectiles Fired at Equal Energies
1. Effects of Different BB Masses Fired at 0.37 Joules (200 fps Using 0.20g)
2. Effects of Different BB Masses Fired at 0.47 Joules (225 fps Using 0.20g)
3. Effects of Different BB Masses Fired at 0.58 Joules (250 fps Using 0.20g)
4. Effects of Different BB Masses Fired at 0.70 Joules (275 fps Using 0.20g)
5. Effects of Different BB Masses Fired at 0.84 Joules (300 fps Using 0.20g)
6. Effects of Different BB Masses Fired at 0.98 Joules (325 fps Using 0.20g)
7. Effects of Different BB Masses Fired at 1.14 Joules (350 fps Using 0.20g)
8. Effects of Different BB Masses Fired at 1.49 Joules (400 fps Using 0.20g)
9. Effects of Different BB Masses Fired at 1.88 Joules (450 fps Using 0.20g)
10. Effects of Different BB Masses Fired at 2.32 Joules (500 fps Using 0.20g)
11. Effects of Different BB Masses Fired at 2.81 Joules (550 fps Using 0.20g)
12. Effects of Different BB Masses Fired at 3.35 Joules (600 fps Using 0.20g)
13. Effects of Different BB Masses Fired at 3.93 Joules (650 fps Using 0.20g)
14. Effects of Different BB Masses Fired at 4.55 Joules (700 fps Using 0.20g)
VIII. Closing Remarks
IX. References
X. Online Calculators
A. MilDot Scope Calculator
B. Relative Energy / Minimum Engagement Distance Calculator
