1.Arrow
The correct length of the shaft is the distance from the top of the shaft to the deepest part of the groove of the arrow tail. This distance includes the length of the arrow tail and part of the base, but the length of the arrowhead and the base outside the shaft is not counted. The recommended length of the arrow should keep the front end of the shaft at least 1 inch (25 mm) away from the base of the arrow, after the normal arching is full. This is to prevent the arrow from falling from the base of the arrow if the pull distance increases unexpectedly.
The significance of the arrow length is to match the pull distance of the shooter and provide the basis for the deflection selection of the shaft.
The following figure shows the measurement criteria for the correct length of arrows.
If the arrow is too short, there is a risk of pulling the arrow down the platform
Generally, the length of the original long arrow is 32 inches. If the arrow is adapted by cutting the length of the arrow, the dynamic deflection of the arrow shaft becomes hardened and the weight of the arrow becomes lighter. However, the static deflection of the arrow remains unchanged.
For the arrows with hunting arrowheads, if the arrow platform and the bow window do not have space for accommodating hunting arrowheads and the arrowhead must extend out of the bow back, then the proper length of the arrowheads should be taken after the bow is normally built. Keep the hunting arrows at least 1 inch (25 mm) away from the bow. Of course, there are other recommended values for arrow length, but they are not commonly used. For details, see the Arrow Compilation in the EASTON Arrow Tuning and Maintenance Guide.
Measurement criteria for correct arrow length after installing hunting arrow.
2.Arrow Weight and Related Impacts
Arrow weight generally refers to the weight of the whole arrow, including the overall weight of the arrow (including the arrow seat), the shaft, the arrow feather and the arrow tail (including the arrow seat or the anti-tapping nail).
The weight of the arrows, in the case of the same weight and length, will affect the speed of the arrow, the aim, the wind resistance of the arrows, the efficiency conversion, and the vibration of the bow. When the weight of the arrow increases and the weight of the bow does not change, the initial velocity of the arrow will decrease, the wind deflection resistance will be improved, and the rate of attenuation of the arrow speed will decrease (the inertia of the heavy arrow is greater). Under the condition of constant firing range, because of low speed of heavy arrow, higher trajectory parabola apex is needed to increase the space time of arrow flight, which requires increasing the initial launching angle, It is also necessary to adjust the aim or sight settings when shooting arrows.
Secondly, the increase or decrease of arrow weight within a certain range will also affect the efficiency of the bow and the kinetic energy of the arrow. Generally speaking, the heavier the arrow, the higher the efficiency of the bow, the bow will feel less vibration, although the arrow speed is slowed, but the arrow's kinetic energy will increase accordingly. However, it is important to note that these correlation changes in the weight of the arrow only make sense to a certain extent, and if the arrow is too heavy, it will have a semi-empty effect. This is because a light arrow cannot convert most of the elastic potential energy into kinetic energy to carry away. As a result, the bow piece needs to absorb the energy of its own rebound. The heavy arrow can convert most of the elastic potential energy into the kinetic energy of the arrow. At the same time, the speed of the arrow and the rebound speed of the bow will be relatively slow, so there will be light arrows, bows raised by heavy arrows.Arrow weights are generally described in the terms of GPI (Grains per Inch) and GPP (Grains per Pound). GPI is related to the length of the arrow shaft. Generally, only the weight of the arrow is calculated as the nominal GPI of the arrow shaft. GPP is related to the pull weight and usually calculates the weight of the whole arrow. (including arrowhead, arrowhead, arrowhead, arrowhead, arrowhead). Due to a light arrow wound bow, some bow chambers prescribe a minimum GPP value for arrows, below which the warranty may be lost. The GPP value of the American Hunter's arrows ranges from 8 to 13 frames per pound, and the common arrows range from 9 to 11 frames per pound. For example, a 30-pound bow will weigh 10 frames per pound. So the arrow weighs 300 grains. Generally, the high weight bow, with a higher GPI/GPP value of the arrow is better, besides protecting the bow, the arrow's flight posture and flight path will be better, and the distance between the target sight points of the gap shooting method will be reduced, which is convenient for aiming. If it is used for outdoor archery, the GPP value can be reduced to obtain a faster arrow speed. Some low-pound bows, such as the 20-pound practice bow, may have a GPP value of between 5 and 9 frames per pound for better speed and trajectory, but less than 5 frames per pound is not recommended.
3.Center Ratio of the Arrow's Center of Gravity
The center of gravity of the arrow (FOC) mainly describes the position of the center of gravity of the arrow relative to the center of the length of the arrow, which will affect the flight attitude and flight path of the arrow, but this parameter belongs to the category of fine adjustment of arrows, and novices need not care too much. ATA Standard (ATA: Archery Trade ).
Association of Bow and Arrow Trade Association, formerly AMO: The formula for calculating the FOC of Archery Manufacturers' Association is as follows:FOC(%)=100%x(A-L/2)/L
where A is: whole arrow (Arrows, Arrows, Arrow Tails Fully Fitted) The distance from the center of gravity to the bottom of the arrow tail chord groove;
L is: the correct length of the arrow, that is, the distance from the top of the shaft (excluding the length of the arrow) to the bottom of the arrow tail chord.
The following figure shows the calculation parameters of FOC.
For example, if a whole arrow with L = 810mm long is an arrow, and the distance from the center of gravity to the bottom of the tail chord slot is A = 495mm, then the FOC ratio of the arrow is 100% x (495-810/2) /810 = 11.1%. The FOC ratio or the center of gravity of the whole arrow can be adjusted by changing the weight of the arrow and the arrow tail. The heavier the arrow, the lighter the arrow tail, the closer the center of gravity will be, and the lower the center of gravity will be moved. The change of FOC has a significant effect on the trajectory of an arrow at long range, but the effect of FOC adjustment is not obvious at short and medium range, but the change of FOC still affects the aim or sight setting of an arrow.
The larger the FOC ratio, the closer the arrow center of gravity is to the arrow, the larger the correction moment of the arrow feathers, the better the correction and the better the stability. However, in the medium and long distance range, the more forward the center of gravity is, the more obvious the bending and falling at the end of the trajectory is. It is necessary to increase the elevation angle of launch, and the accuracy of the arrow's landing point is more sensitive to the initial velocity and angle of launch, but the arrow at the end of the trajectory can convert more gravitational potential energy into the kinetic energy of the arrow, which can compensate for the terminal velocity.
The smaller the FOC ratio, the closer the center of gravity of the arrow to the midpoint of the arrow length, the lower the efficiency of the arrow feather correction, but the flight path of the arrow will be smoother, and the sensitivity of the landing accuracy to the initial conditions will be reduced.The recommended FOC ratio is about 9% to 15%.The recommended values for FOC in the EASTON Arrow Tuning and Maintenance Guide are also broken down: The recommended FOC value of aluminum target arrow is 7% ~ 9%, and the A/C/C target arrow (Aluminum/Carbon /Composite Arrow).The recommended FOC value of Composite Arrow is 9% ~ 11%, A/C/E (Aluminum/Carbon/Extreme Composite Arrow) is 11% ~ 16%, and hunting arrow is 10% ~ 15%. General senior shooter or professional shooter will be in the adjustment of the arrow and fixed a relatively appropriate FOC value.
The following figure shows the trajectory comparison of different FOCs of arrows
4.Arrow Speed
The arrow speed is the initial velocity measured at close range after the arrow branch is away from the string. Currently, there are two main standards for the measurement of arrow speed, one is the IBO standard (IBO: International Bowhunting Organization (ATA: Archery Trade Association). Because different weights and weights produce different speeds, the speed measurement under the standard system limits the pull and weight of the bow. The IBO measure is the speed measured at 350 reams of arrows at a distance of 30 inches and a distance of 70 pounds, i.e. the speed of arrows weighing 5 reams per pound. The ATA (formerly AMO) measures the speed of an arrow measured at 540 reams at a 30-inch pull and 60-pound pull, i.e., an arrow weighing 9 reams per pound. It can be seen that the IBO's arrow speed is measured in the case of light arrows, so the measured arrow speed is usually higher, and the ATA's measurement standard is more close to the actual weight of the arrows used by the American Hunt, and the reference is more accurate.
Arrow speed is usually measured in FPS (Feet Per Second) feet per second, although it can also be divided by 3.28 (1 meter = 3.28 feet).
Under the configuration of common pounds and arrow weight, the US arrow hunting speed is generally 170FPS ~ 190FPS. (51. 8m/s ~ 57.9m/s) In between, if you use a high-pound, high-performance conversion bow, or if you use a lighter arrow, you can reach speeds of 200 to 240 FPS (61m/s ~ 73.2m/s) Of course, there is also a record for archery speed exceeding 300 FPS (91.4 m/s), but this record for compound archery level requires a very high number of pounds for Beauty Hunt, which is of little practical significance.
The speed of the arrow mainly affects the trajectory of the arrow over medium and long distances and its relative resistance to wind deflection. At the same range, the higher the speed of the arrow, the slower the trajectory, the lower the trajectory, and the shorter the flight time of the arrow. the less the influence of wind deviation. In addition to the weight of the bow and the weight of the arrow, the efficiency of the bow will also have a significant impact on the speed of the arrow. If the bow with the same distance and weight is higher, the speed of the arrow will be faster if the bow is the same weight. The speed of the arrows is usually measured by an astronomical velocimetry, in which the shooter simply shoots the arrow from the astronomical frame at close range, and is usually measured in feet per second and meters per second.
The following figure shows the comparison of the trajectory of different arrows
The following figure shows the sky curtain
5.The effect of consistency of the whole arrowEveryone knows that a shooter's skill level will determine his final result. Only a reasonable technical system and a high degree of consistent repetition of movements can achieve the best result. However, there is also a condition that each arrow used by the shooter must be consistent in all parameters. so as to ensure the stability of the output of the action result; Specifically, each arrow must have a high degree of consistency or only a slight error in the length, weight, specifications of arrow and tail, shaft diameter, static deflection, feather size, and even the tightness of the tail. (For example, a dozen arrows of high quality can be controlled within ± 1 grain.) can make the shooter establish a stable archery system, ensure that when the arrow falls off, the first time can eliminate the cause of the equipment, more accurate and effective adjustment to the movement.Conversely, if there are different specifications between the arrows, even if the movement system achieves a high degree of mechanical consistency, the arrow's landing point will be significantly deviated. For example, the length of the arrow, weight, FOC and other differences, there will be high and low drop; If the static deflection of the arrow and the specification of the arrow tail are different, the arrow may cause the left and right falling points, and due to the interference of equipment, it will be difficult for the shooter to analyze the cause of the deviation from the falling point of the arrow. It is difficult to distinguish, and the more the action is adjusted, the more disorderly the result, which is not conducive to the stable shaping of the action.
Generally, after the bow is adjusted, the output of the bow will not be much different as long as the consistency of the bow is ensured. Therefore, the consistency of the archery is generally the key to the accuracy of archery. The consistency of the arrow is the second, and the output performance of the bow is the last. Therefore, a dozen arrows of consistent quality and consistent parameters are essential for accurate shooting. Of course, if the shooter has a high level of movement consistency, it can in turn be able to detect deviations of the equipment.