DARPA’s Self-Steering Bullets

Think Angelina Jolie shooting curved trajectory shots with her gun in the movie Wanted. Well, the end result is not exactly fictional anymore (the technique is). I recently stumbled upon the following video demonstrating DARPA’s new self-steering bullet technology and it blew my mind.Here’s the video:

The video shows new missile-like self-steering projectiles hitting a moving target, only this time these are not missiles but 0.5 caliber sized sniper bullets (0.5 inches internal diameter of the gun’s barrel). As seen in the video, enabled by technology, a novice-sniper seems to be able to make a fairly good shot. On a funnier note, I see it like the autotune technology that helps music artists to fit their out of tune recording to a perfect tune.

Jokes aside, watching this smart bullet change its path mid-air, stirred up the curious cat that lives in my head. I would have had a tough time sleeping without knowing how DARPA’s self-steering bullet actually works. So, armed with free journal access (being a Ph.D. student has its perks), I fired up my google scholar and started looking for white papers with some mention of these keywords. With this technology being developed under DARPA, it’s of course one of those hush-hush things and was sure I won’t find much. Still, I was happy to glean a tiny hint of its inner workings.

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The Great Pyramid is not Your Average Square Pyramid

Over the years, I have been fed with one shocking new fact a time about the Pyramids the Egyptians built over 3,800 years ago. Although not anywhere even close to being a new fact, this is the latest fact I have uncovered about the Great Pyramid of Giza, or the Pyramid of Khufu – The largest and the oldest of all the three pyramids in the Giza pyramid complex.

When observed carefully, what actually looks like an average square pyramid with four visible sides, that actually isn’t the case. Technically, there are eight visible sides. Here’s an exaggerated cartoon of what I mean by the eight sides.

concave2

In fact, the Menkaure, the third pyramid at Giza and the Red Pyramid at Dahshur have also been observed to have a similar concavity to each of their faces!

I know it is hard to believe, just because not many a people talk about it. For that, here are a few images of what it looks like from up above.

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The Principles of Building Indestructible Sand Castles

Introduction

If you had a formal education that touched even a little bit of composite materials in the course, you will immediately be able to recall what these amazing materials can do. For others, Composite materials, as the name suggests, are materials that are composed of two or more different kinds of materials.

In a simple case think of your body, which is, in a broad sense, a combination of skin material and bone material. These materials are designed to take advantage of the contrasting properties of, say two different materials. For simplicity’s sake, skin is soft and bone is hard. The bone gives body a solid structure, while the skin and muscle tissues enables this hard skeleton to make fluid movements – flex or bend – and still be together.

Individually the materials that make up a composite material are not very capable. But when they come together, composite materials can blow your mind. To appreciate how this simple coming together of two humble materials can create a super material, and to appreciate the mind blowing properties it can have, let us first look at what most of us have heard of – “Carbon Fiber”. We will get into the more mind bending aspect of composites after that.

Carbon Fiber Reinforced Polymers (CFRP)

Now carbon fiber itself isn’t a composite material. As the name suggests, it is a fiber of carbon. The fiber is composed of strands of carbon each of which are much thinner than a single human hair. Hundreds of these come together to form a thicker fiber. This fiber can be woven to make sheets or the carbon fiber itself can directly be used in a composite material.

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