Balance Flight – Projectile Stabilization for Increased Distance and Accuracy
A projectile begins its trajectory once it emerges from the bore and from the A projectile begins its trajectory once it emerges from the bore and from the
accompanying expanding
accompanying expanding gases. gases. The signature The signature of the prof the projectile’s trajectory in ojectile’s trajectory in flight isflight is influenced by a number of factors – some associated with the projectile itself, some influenced by a number of factors – some associated with the projectile itself, some associated with the atmosphere in which the projectile translocates and some associated associated with the atmosphere in which the projectile translocates and some associated with the earth’s gravitational forces.
with the earth’s gravitational forces.
To present a complete picture of a projectile’s trajectory in flight, one should integrate all To present a complete picture of a projectile’s trajectory in flight, one should integrate all three factors.
three factors. In this particular In this particular case, we shall case, we shall focus on the focus on the projectile itself with only projectile itself with only passing reference to the atmosphere and to the earth’s gravitational forces.
passing reference to the atmosphere and to the earth’s gravitational forces.
A projectile’s mass, diameter, shape as well as axial spin rate are characteristics that A projectile’s mass, diameter, shape as well as axial spin rate are characteristics that
influence its
influence its trajectory signature in trajectory signature in flight. flight. These characteristics are These characteristics are only important whenonly important when viewed in relation to a defined speed of the projectile in flight.
viewed in relation to a defined speed of the projectile in flight.
If the projectile travels far enough without first hitting a target, it will experience three If the projectile travels far enough without first hitting a target, it will experience three speed zones:
speed zones: supersonic, transonic supersonic, transonic and subsonic. and subsonic. Conditions in Conditions in the atmosphere the atmosphere affectaffect speed.
speed. It is considered It is considered to be a to be a fluid with vfluid with varying characteristics arying characteristics including its including its density,density, temperature, vis
temperature, viscosity and wind cosity and wind directory. directory. Speed in flight Speed in flight is measured as is measured as a value calleda value called Mach (M).
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There are five factors that separately contribute to drag force. There are five factors that separately contribute to drag force.
•
• Skin frictionSkin friction •
• Pressure dragPressure drag •
• Base dragBase drag •
• Wave drag Wave drag •
• Yaw-dependent drag Yaw-dependent drag
Skin friction results from
Skin friction results from the viscosity of the fluid. the viscosity of the fluid. Viscosity is defined as the Viscosity is defined as the resistance of resistance of the shearing
the shearing motion of motion of the fluid. the fluid. When a When a projectile moves through projectile moves through the atmosphere,the atmosphere, molecules immediately adjacent to the surface cling firmly to the surface while those
molecules immediately adjacent to the surface cling firmly to the surface while those adjacentadjacent to the surface
to the surface flow parallel to it. flow parallel to it. So there is So there is an area where an area where shearing occurs;shearing occurs; i.e i.e ., boundary ., boundary layer.
layer. This contrThis contributes to ibutes to pressure drpressure drag.ag.
Generally, the average static pressure at the front of a projectile is greater than that found at Generally, the average static pressure at the front of a projectile is greater than that found at
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The total drag is the sum of all drags.
The total drag is the sum of all drags. Taking into effect the air density and forward speed of Taking into effect the air density and forward speed of the projectil
the projectile, a ve, a value withoualue without units t units can be can be determined. determined. This is This is drag coeffdrag coefficient. icient. DragDrag coefficient is used as a measurement of
coefficient is used as a measurement of projectile efficiency during flight depending upon theprojectile efficiency during flight depending upon the speed of the projectile.
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Balanced Flight Balanced Flight
It is clear that a projectile being able to retain stability throughout its flight will go farther It is clear that a projectile being able to retain stability throughout its flight will go farther and will be more accurate.
and will be more accurate.
Warren Jensen, partner and designer at Lost River Ballistic Technologies® identified the Warren Jensen, partner and designer at Lost River Ballistic Technologies® identified the conditions that could be translated into projectile design, which would exhibit very long conditions that could be translated into projectile design, which would exhibit very long distance accuracy
distance accuracy. . The concept is called Balance Flight and is patented (6,629The concept is called Balance Flight and is patented (6,629,669).,669). Working with PRODAS software, Jensen designed projectiles in
Working with PRODAS software, Jensen designed projectiles in multiple calibers, where themultiple calibers, where the linear drag on a
linear drag on a projectile is matched to its rotational drag. projectile is matched to its rotational drag. In other words, forward rate In other words, forward rate of of deceleration and an axial rate
deceleration and an axial rate of deceleration are balanced. of deceleration are balanced. The gyroscopic stability remainsThe gyroscopic stability remains constant resulting in the projectile remaining on its original trajectory path.
constant resulting in the projectile remaining on its original trajectory path.
Non-balance flight occurs when a projectile’s spin is too great, thus leading to an "over spin" Non-balance flight occurs when a projectile’s spin is too great, thus leading to an "over spin"
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Balanced Flight’s improvements of projectiles in the 40 caliber went far beyond expectations. Balanced Flight’s improvements of projectiles in the 40 caliber went far beyond expectations. Could a Balanced Flight
Could a Balanced Flight improve the 50 cimprove the 50 caliber projectiles? aliber projectiles? The answer is yes, The answer is yes, but it wouldbut it would require specific changes to standard 50
require specific changes to standard 50 BMG land, groove, and BMG land, groove, and twist configurations.twist configurations. Combined with the CheyTac
Combined with the CheyTac®® cartridge case, the .408 projectile has found an idealcartridge case, the .408 projectile has found an ideal launching platform.
launching platform. This platform represents the best long-This platform represents the best long-distance cartridge to date – in alldistance cartridge to date – in all ballistic-char
ballistic-characteristic, including kinetic acteristic, including kinetic energy.energy.
CheyTac
CheyTac®® AssociatesAssociates
363 Sunset Drive 363 Sunset Drive Arco,
Arco, ID. ID. 8321383213
November, 2004 November, 2004