science

Smart bullet

Smart bullet is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Smart bullet rather than just read about it. In short: A smart bullet is a bullet that is able to do something other than simply follow its given trajectory, such as turning, changing speed or sending data. Such a projectile may be fired from a precision-guided firearm capable of programming its behavior.

Key takeaways

Smart bullet belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Smart bullet to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Smart bullet from memory before moving on to harder problems.

Reference excerpt

A smart bullet is a bullet that is able to do something other than simply follow its given trajectory, such as turning, changing speed or sending data. Such a projectile may be fired from a precision-guided firearm capable of programming its behavior. It is a miniaturized type of precision-guided munition.

Types of smart bullets In 2008 the EXACTO program began under DARPA to develop a "fire-and-forget" smart sniper rifle system including a guided smart bullet and improved scope. The exact technologies of this smart bullet have yet to be released. EXACTO was test fired in 2014 and 2015 and results showing the bullet altering course to correct its path to its target were released. In 2012 Sandia National Laboratories announced a self-guided bullet prototype that could track a target illuminated with a laser designator. The bullet is capable of updating its position 30 times a second and hitting targets over a mile away. In mid-2016, Russia revealed it was developing a similar "smart bullet" weapon designed to hit targets at a distance of up to 10 kilometres (6.2 mi).

Guided bullet The guided bullet was conceptualized by Dr. Rolin F. Barrett Jr. and patented in August 1998. As first designed, the bullet would have three fiber-optic based eyes (at minimum, for three-dimensionality), evenly distributed about its circumference. To activate its guided nature, a laser is pointed at a target. As the bullet approaches its final destination, it adjusts its flight path in real time to allow an equivalent amount of light from the laser to enter each eye. The bullet would not travel in multiple directions as though it were an autonomous vehicle, but instead, would make small adjustments to its flight path to hit the target precisely where the laser was placed. Moreover, the laser would not have to originate from the source of the bullet, allowing the projectile to be fired at a target beyond visual range. To allow the bullet to modify its flight path, the body was designed as a metal and polymer combination. The polymer would act as a deformable surface that would deflect the air-stream and steer the bullet in real time. The guidance system is powered by a miniature lithium-polymer battery that is connected to the navigational circuits. Barrett went to great lengths to model the airflow of the bullet, studying butterflies with speed bumps to evaluate the effects of protruding surfaces. Due to a lack of ballistic programs at the time, custom simulations were written in Mathcad to solve for numerous flight variables. In addition to modeling the flight, the interior ballistics were modeled by continuously altering polynomial curves until they were in agreement with publicly available data. Due to a lack of available terminal ballistics data that would have been representative of the guided bullet, the data was compared to that of large game hunting bullets.

Changing trajectory One kind of smart bullet is a projectile that is capable of changing its course during flight. One use of this would be to enable soldiers to stay behind protective cover and shoot around corners. One implementation uses a spoiler and micro gyro to control the bullet.

Navigating Honeywell Aerospace has produced inertial measurement units based on MEMS and microelectronics technologies that it claims can survive the shock of being fired out of a gun.

Transmitting data Another type of smart bullet is one that can transmit data about the location that has been hit. A prototype has been created by researchers at the University of Florida in Gainesville, Florida, USA with funding from Lockheed Martin. The bullet (projectile) has the capability to send data up to a distance of 70 meters.

Worked examples

Example 1 — a first encounter with Smart bullet

Start with the simplest possible case. Write down what Smart bullet claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Smart bullet before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Smart bullet ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Smart bullet

In research: Smart bullet appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Smart bullet in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Smart bullet is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ammunition, Guided weapons, Smart devices, so understanding it makes those chapters shorter.
In everyday life: Look for Smart bullet outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Smart bullet in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Smart bullet means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Smart bullet out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Smart bullet in simple terms?

Why does Smart bullet matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Smart bullet?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Smart bullet.