The flight speed of the bow arrow in meters per second (m / s) directly depends on the tension strength of the bowstring, the weight of the arrow itself and the efficiency of a particular bow model. For a standard 22 kg Olympic recursive bow, the initial speed of the light training boom is approximately 50-55 m/s, while a powerful block bow can accelerate the projectile to 90-100 m/s and above. These indicators are critical for the calculation of the flight trajectory, since even a small deviation in the initial speed significantly changes the point of hit at distances over 50 meters.
It is important to understand that the manufacturer’s stated speed (often referred to as IBO speed or FPS) is always measured under ideal laboratory conditions using a strictly defined weight boom. In real shooting conditions, the actual speed is always lower than the nominal speed due to the use of heavier pointed tips, additional stabilizers and individual features of the shooter's technique. That is why the calculation of ballistics should be based on the real parameters of your equipment, and not only from the data on the box.
To accurately determine the speed of the arrow, it is necessary to take into account the interaction of three main components: the accumulated energy of the bow shoulders, the mass of moving parts (the bow, the arrow, part of the mass of the shoulders) and losses to friction and vibration. Understanding the physics of this process allows the arrow to correctly match the stiffness of the pole (spine) and the mass of the tip to minimize the spread of hits. Below we will discuss in detail how these values are calculated and what affects the final result in meters per second.
Physics of the shot and calculation of speed
The firing process is the conversion of potential energy accumulated in the bow's bent shoulders into the kinetic energy of the flying arrow. According to the laws of physics, not all energy is transferred to the projectile; a significant part is spent on the movement of the bow string itself, the shoulders of the bow and overcoming air resistance. Kinetic energy Arrows are calculated by the formula, which takes into account the mass of the arrow and the square of its speed. This means that even a small increase in flight speed requires exponentially more energy from the bow.
Efficiency of energy transmission, or Onion efficiencyIt varies depending on the design. In traditional onions, this figure can be about 70-75%, while modern block bows with eccentrics reach 80-85% and above. It is the high efficiency that allows block models to develop record speeds with a relatively comfortable retention force for the shooter. However, it is worth remembering that an overly light arrow causes excess energy to return to the bow's shoulders, causing strong vibrations and potentially damaging the structure.
Foot-per-second (FPS) velocity calculations are often used, as most international standards and chronographs use the imperial system. The formula is simple: the FPS value is divided by 3.28. For example, a speed of 280 FPS corresponds to about 85.3 m/s. The accuracy of this calculation is critical for setting sighting slats, especially when shooting at long distances, where an error of 1-2 m / s can lead to a miss vertically of several centimeters.
⚠️ Attention: Using arrows too light for your bow (less than 5 grains per pound of tension) can cause shoulder breakage or damage to eccentrics due to a high-recoil “idle” shot.
The effect of the mass of the boom on the speed is inversely proportional: the heavier the projectile, the lower its initial speed, but higher is inertia and penetration. Light arrows fly faster from the bow and have a gentler trajectory, which makes it easier to aim at unknown distances, but they are more susceptible to wind demolition. Heavy arrows fly slower, the arc of their flight is steeper, but they retain energy better at a distance and are less dependent on gusts of lateral wind.
Factors affecting flight speed
The final speed of the arrow is influenced by many variables that are often overlooked by novice arrows. The primary factor is tension (Draw Weight) An increase of 1 pound of tension typically adds about 1.5-2.5 m/s (5-8 FPS) to the flight speed, provided the boom weight is maintained. However, the infinite increase in tension has its limits, determined by the physical capabilities of the shooter and the structural strength of the bow.
The second critical parameter is traction (Draw Length) The longer the thrust of the shooter, the greater the path the bowstring passes, dispersing the arrow, and the more energy is stored in the shoulders. An increase in thrust length by 1 inch can add 3 to 5 m/s to the speed. This explains why the same bow tuned to different arrows will show different results on a chronograph. It is also important to consider the type of bowstring and its weight: lighter threads (e.g., from Dyneema material) allow for higher speeds compared to heavy Kevlar counterparts.
The ambient temperature also makes its own adjustments to ballistics. In cold weather, the shoulder materials become stiffer, and the lubrication in the mechanisms of block bows is thicker, which can slightly reduce speed. In addition, the density of air depends on temperature and pressure: in hot rarefied air, the arrow flies with less resistance, theoretically maintaining the speed better, although the initial speed from this changes insignificantly.
The impact of accessories on speed--
Installation of heavy stabilizers, shelves and kivers increases the total weight of moving masses or creates additional resistance, which can reduce speed by 1-3 m / s. Accurately adjusting the equipment requires re-shooting.
And we must not forget that shot-playing. A sharp but controlled break from the lead, the absence of a blockage of onions and clean back work ensure the most efficient transfer of energy. Errors in the technique, such as "hitting" the bow at the time of shooting or uneven extension of the hands, lead to loss of speed and, as a result, to deterioration of accuracy.
Comparison of the speed of different types of onions
Different bow designs demonstrate fundamentally different speed indicators due to the peculiarities of energy accumulation and return. Traditional bows, such as long bows (Longbow) and recursive bows without blocks, have the lowest speed in terms of tension. Their shoulders work linearly, and a significant part of the energy remains in the shoulders themselves at the time of the bowstring.
Block bows (Compound) are leaders in speed characteristics due to the system of eccentrics. This mechanics allows you to accumulate maximum energy with less retention force at the end point (let-off), as well as optimize the acceleration of the boom at different stages of thrust. Speed characteristics Blockers often exceed 90 m/s, making them preferred for hunting and 3D shooting, where trajectory decking is important.
Below is a table showing approximate speed ranges for different types of bows under standard test conditions (tension about 27-30 kg, standard thrust length):
| Type of onion | Average speed (m/s) | Average speed (FPS) | Features |
|---|---|---|---|
| Traditional (Longbow) | 45 - 52 m/s | 150 - 170 FPS | Smooth shot, low noise |
| Olympic recursive | 50 - 60 m/s | 165 - 195 FPS | High accuracy, medium speed |
| Block (Compound) | 75 - 95 m/s | 250 - 310 FPS | Maximum speed and energy |
| Pneumatic (Airbow) | 100 - 120+ m/s | 330 - 400+ FPS | Record numbers, specific |
The choice of bow type should be based not only on the desire to get the maximum speed, but also on the tasks that the shooter faces. For the Olympic shooting at 70 meters, stability and repeatability are important, not record m / s. For hunting, high speed is critical so that the animal does not have time to react to the sound of the shot (since the sound goes at a speed of 340 m / s, and the arrow is slower, but the faster the arrow, the less the difference in the time of the arrival of the sound and the projectile).
Calculation and measurement of speed (Chronographs)
To obtain accurate data on the speed of your bow-arrow bundle, you need to use specialized equipment. chronograph. These devices, such as popular models Bushnell Velocity or LabRadarThey record the time of passage of a certain segment of the path and calculate the instantaneous speed. Using a chronograph is the only way to objectively assess the effectiveness of tuning the onions.
The measurement process requires strict safety rules and procedures. The chronograph is set at a certain distance from the firing line (usually 1-2 meters) so that the sensors have time to activate, but the boom has not yet lost a significant part of its speed due to air resistance. The arrow must fly strictly through the center of the measuring gate, otherwise the readings will be distorted or not counted at all.
☑️ Bow and arrows warmed up (made 10-15 blank or training shots)
When conducting a series of measurements, it is important to pay attention not only to the average value, but also to the spread (standard deviation). If one shot shows 80 m / s, and the next 75 m / s with the same technique, this indicates problems with consistency of equipment. The reasons may be in the heterogeneous weight of arrows, defects in plumage or unstable work of eccentrics. A good result is considered a spread within 1-2 m / s.
⚠️ Attention: Never shoot through a chronograph without a catcher box on the opposite side unless you are in a specially equipped dash. An arrow that flies past a target retains its deadly power.
Effect of arrow mass on ballistics
Arrow mass is the variable that the shooter can control most easily by changing tips or poles. There's a concept GPP (Grains Per Pound) The number of granular weights of the arrow per pound of the bow tension force. The optimal value for most bows is considered to be the range of 6-8 GPP. Decreasing this indicator increases speed, but increases the risk of damage to the onions.
A heavy arrow, despite its lower initial speed, often performs better on the hunt. This is due to the fact that it has a greater momentum and better penetrates tissue, passing through. A light speed boom can get stuck in a rib or lose energy when faced with an obstacle. In addition, the heavy arrow makes less noise when fired, as most of the energy goes into the movement of the projectile, rather than the vibration of the bow.
When the mass of the arrow changes, it also changes. spike (toughness). The heavier arrow behaves as softer in flight. Therefore, when switching to heavy hunting tips, it is necessary to check whether the group of hits becomes worse. Sometimes heavy arrows require a bow with greater tension or a stiffer pole.
For silent shooting, increase the weight of the arrow. This will reduce the speed by 3-5 m / s, but significantly reduce the vibration and sound of the shot, which is critical for hunting.
The practical importance of speed for shooting
Knowing the precise speed of the boom is necessary for the correct setting of the sighting bar or calibration of the optical sight. Modern sights allow you to enter the speed value (FPS or m / s), after which the electronics or mechanics recalculate the position of the horizontal thread for different distances. An error in the entered speed will lead to systematic errors: if the real speed is lower than the entered, the arrows will fall below the aiming point at long distances.
The trajectory accuracy provided by high speed makes it easier to fire at moving targets or unknown distances. At high speed, the arrow falls less under the influence of gravity, so the error in determining the distance to the target affects less. For example, at a speed of 90 m / s, the error in determining the distance of 5 meters will be less critical than at a speed of 50 m / s.
However, chasing speed records is not always justified. In disciplines requiring maximum accuracy (e.g. FITA/World Archery), arrows are often selected heavier than optimal for speed to obtain a more stable flight and less influence from external factors. Balancing speed and stability is the key to success in any kind of archery.
Speed is important, but stability and the right selection of equipment for your equipment is more important than record performance m / s.
FAQ: Frequently Asked Questions
How to convert FPS to meters per second (m/s)?
To convert feet per second (FPS) to meters per second, you need to divide the FPS by 3.28. For example, 300 FPS/3.28 ≈ 91.4 m/s. Conversely, to get FPS, multiply m/s by 3.28.
Why does my arrow fly slower than the manufacturer claims?
Factory speed is indicated for ideal conditions: a standard boom of 350 grains, a tension of 30 kg (70 lbs), a thrust length of 76 cm (30 inches). If your arrow is heavier, the tension is less or the thrust is shorter, the actual speed will be lower than the stated speed.
Does humidity affect the speed of the arrow?
The effect of humidity is minimal and in practical shooting is often negligible compared to the effect of temperature and pressure. However, high humidity can slightly increase the weight of wooden elements of the arrow or string, theoretically reducing the speed by a fraction of a percent.
Can I increase the speed of the bow without replacing the shoulders?
Yes, speed can be increased by using a lighter string (e.g., 100% Dyneema), setting speed modules to eccentrics (if design permits), reducing the weight of accessories, or using lighter arrows (within reasonable safety limits).
What speed is dangerous to humans?
Any arrow fired from a combat or sports bow is potentially fatal. Even bows with a tension of 10-15 kg can penetrate the skin and muscles. The speed of the archer for survival is usually 40-50 m / s, which is already enough to cause serious injuries.