Please post your comments, sources of information, books, Internet links, etc. in regards of Air Rifle balistics in here. The more technical, the better
This is gonna be interesting!
Let's ask a few questions to get people interested:
- What exactly influences air rifle accuracy?
- What effect does super-sonic speeds have on pellet ballistics?
- What effect does atmospheric conditions have on ballistics? (temperature, barometric pressure, relative humidity)
- Does pellet shape have anything to do with accuracy?
- What happens with all of that energy after you pull the trigger?
- Is it possible to make more efficient use of the energy and transfer more of it to the pellet?
- Why are some pellets more accurate than others?
- How much does external factors influence pellet flight, and why?
I can kind of answer no 2 - having studied aerodynamics (including supersonic aerodee) in the AirForce. I'll try and give you a short answer, but whole books have been written on the subject (not small books either!)
As you approach the speed of sound the pellet will be in a transonic state (Starts at around Mach 0.8). This, contrary to popular belief, is not an actual speed. The actual speed depends on a number of factors including altitude and temperature.
During transonic speed the air cannot "get out of the way" fast enough and builds up in front of the pellet. This makes it very unstable and new laws of aerodynamics start to come in.
Also while in this transonic state the drag on the pellet is increased by a huge amount with the introduction of wave drag combined with parasitic drag. Induced drag should no longer be a factor at these speeds.
Once the pellet passes through the transonic and into the supersonic (Mach 1.2) then things start to settle down in a properly designed pellet.
The sonic crack is caused by the shock wave that has been built up in front of the pellet and as the pellet passes through it radiates the shock wave out for us to hear.
This shock wave is used as a psychological tactic by some pilots to break windows etc without firing a shot.
Hope that helps!