Team: 46
School: LAS CRUCES HIGH
Area of Science: Physics
Interim:
Problem Definition: In the times before firearms, special archers trained to hit certain people. They were the medieval versions of snipers. Since the invention of the gun, snipers have been used in every major conflict. However, not every army trained people specifically as snipers. Most of the soldiers who learned sniping skills were sharpshooters (elite infantry). However, with the advent of automatic weapons, snipers became their own category. They used to use bolt action rifles because of their accuracy and stealth. Semi-automatic sniper rifles that were accurate proved too expensive to manufacture in the past. However, due to recent advances in technology, the sniper rifle currently used by the US Army (M107) is an accurate semi-automatic sniper rifle. There are some problems related to the M107, though. It's very loud, which can give away the sniper's position. The only compensation for this is that they are usually aiming at distant targets. Also, the scope has a zoom of 500, 1000, and 1500 meters. This unfortunately causes shots between 1000 and 1500 to be inaccurate. Lastly, shooting at an uphill angle can injure the sniper.
The focus of our project is on the targeting systems. For shots over 1000 yards, the targeting systems used to be inadequate. Mil dots in the scope are used to measure the angle of the target. This is 1/1000th of a radian. The mil dots form a coordinate plane on the scope. Once zoomed in to the appropriate zoom level, the sniper calculates the angle at which he has to aim at the target in order to hit. The scope magnification tells the sniper the distance, which in turn determines what angle above horizontal the shot must be made at to compensate for gravity. An experienced sniper can estimate this very well, or use a Bullet Drop Compensator (BDC). The BDC and other devices that measure elevation, wind, and other relevant factors are built into the scope. These devices have knobs that are turned to calculate the effects of the factor, when matched to the appropriate value of a known variable. In the case of gravity, the known variable is distance to the target. However, the height of the target must be guessed. Replacing this with visible laser rangefinders is not encouraged because lasers can be seen by the target, especially if the target is employing night vision goggles, which gives away the sniper's position. Some lasers are invisible, but those are weak magnifiers, so they take a lot of power in order to travel distances in excess of a mile. Under the old system of scopes, magnification could only go up to 11X, so the target's height wasn't too easy to calculate. Also, the target was blurry due to glare problems. A large (50mm)objective lens that's coated to allow more light to enter restricts glare problems, and the magnification limit has been raised to 14X on commercial models. This allows snipers to make shots at a maximum of 2000 meters, though the scope can only zoom up to 1500 meters. At such distances, gravity plays a much larger role in the bullet's trajectory. The BDC solves this problem but the distance has to be inputted manually. With the other measurement rings, the sniper can obtain information on other factors such as wind speed, elevation, and other factors. Experienced snipers already know how to estimate these factors that are built into the scope but it still requires calculation or input time. Likewise, aiming at moving targets requires estimation. Any form of estimation creates chances of error. A machine or computer program would be much more precise and faster. If the scope could measure the distance, wind speed, elevation, movement, and other relevant factors, it could feed this data directly into a program that tells the sniper where to aim. No more calculation time is required. We want to make a program that obtains the relevant factors, then applies them. This program would be incorporated into the scope and would automatically tell the sniper where to aim. Our program will allow snipers make much more frequent shots. If we could get such an opportunity, we want to measure how much time this saves for every shot. Also, we want to measure the increase in accuracy. Both of these factors will be considered at short and long distances. We want to see if there's any significant difference in the short and long difference data. Lastly, we want to see if this can increase a gun's effective range. If we can't get an actual person to do such things, we will have to research average accuracy at such ranges as well as average times between shots.
Problem Solution: Ideally, we want to have a professional sniper team with the M107 for the experiments. We'll measure the relevant factors on the testing grounds before they shoot at targets from 500 meters. We will input those into the computer and we'll see if the computer comes up with the same angle as the sniper. This is to test the program's accuracy. Then, we will measure their average time between shots. We will give them 20 targets per trail and have around 10 trials. While they fire at these targets from 500 meters, we measure their accuracy as a percentage. Then, we extend trails into 1500 meters. We again measure time and accuracy. We then compare and analyze the results between the two, especially if distance effected time and accuracy. To see if our scope improves accuracy or time, we must have a scope with this program on it, and then see if the gunners can improve their ability to aim with this scope. Similar data will be measured and this will be compared to the control (without scope trials). To see if the new scope increases range, we will have to set up a target that exceeds the gun's maximum effective range and see if the snipers can consistently hit the target. The maximum range is 1869 meters so we'll set this up at 2200 meters. Consistency is an accuracy rate greater than 50%. Realistically, we might have to use research instead to obtain the data of normal snipers and make a model of a sniper with the scope. This model will simulate the bullet's trajectory that includes temperature, wind velocity, elevation, barometric pressure, and distance as input variables. This model has gravity, air resistance (ballistic coefficient or how much the bullet slows down over a given amount of time), and momentum as formulas. This model is set on the appropriate zoom magnification which is determined by distance. Bullet type, weight, and speed, gun model, and curvature of the earth are givens. The output variable is the angle of attack.
Progress to Date: Our project is going well. The webpage is completed. The research containing the specifics of snipers, lasers, and current technology is finished. The research dealing with factors that effect trajectory (wind, bullet type and weight, elevation) is also complete. The program will contain a basic model of a sniper's bullet trajectory. Proportion of scope vision to real world space, bullet type, weight, and speed (match-grade .50 caliber with 660 grains that initially moves at 2800fps), gun (M107), elevation (flat), and curvature of earth (none) are givens for now. Gravity is one of the formulas we'll use as well as air resistance (ballistic coefficient) and momentum. The wind speed and distance are input variables. All these variables determine angle of shot (output). Then, we will add the other relevant factors.
Expected Results: Given the accurate scope of the M107, I doubt we could improve accuracy. I think the program will decrease time because the scope adjusts to the next target almost instantly and there's no calculation time. I don't think the range will be increased because there's a limit on how far the bullet can actually go consistently. I think that limit is the maximum effective range.
Sources: http://www.globalsecurity.org/military/systems/ground/m107.htm
http://www.uslink.net/~tom1/calcbc/calcbc.htm
http://en.wikipedia.org/wiki/Sniper
www.thehighroad.org/showthread.php?s=&threadid=2265
http://science.howstuffworks.com/laser10.htm
appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&...
Team Members: Justin Cross, Chris Smith, Mi Deng, Ryan Dailey, Daniel Parrott
Teacher: Greg Marez
Team Members:
Mi Deng
Justin Cross
Christopher Smith
Ryan Dailey
Sponsoring Teacher: Gregory Marez