Spacecraft rocket engines come in a variety of forms and use a variety of fuels, but most rely on chemical reactions to blast propellants out of a nozzle, with the reaction force driving the spacecraft in the opposite direction. These rockets offer high thrust, but they are relatively fuel inefficient and thus, if you want a large change in velocity, you need to carry a lot of heavy fuel. Getting that fuel into orbit is costly, too!
Ion thrusters, in their various forms, offer an alternative solution – miniscule thrust, but high fuel efficiency. This tiny push won’t get you off the ground on Earth. However, when applied over a great deal of time in the vacuum of space, it can lead to a huge change in velocity, or delta V.
This manner of operation means that an ion thruster and a small mass of fuel can theoretically create a much larger delta-V than chemical rockets, perfect for long-range space missions to Mars and other applications, too. Let’s take a look at how ion thrusters work, and some of their interesting applications in the world of spacecraft!
Continue reading “Ion Thrusters: Not Just For TIE Fighters Anymore”
When electric cars first started hitting the mainstream just over a decade ago, most criticism focused on the limited range available and the long recharge times required. Since then, automakers have been chipping away, improving efficiency here and adding capacity there, slowly pushing the numbers up year after year.
Models are now on the market offering in excess of 400 miles between charges, but lurking on the horizon are cars with ever-greater range. The technology stands at a tipping point where a electric car will easily be able to go further on a charge than the average driver can reasonably drive in a day. Let’s explore what’s just around the corner.
Continue reading “Longer Range EVs Are On The Horizon”
All feats of engineering build on a proper understanding of the basic engineering concepts. Learning these concepts from a book or class tends to be a rather uninspiring exercise, unfortunately. To make this task a lot more enjoyable, [The Efficient Engineer] has produced a series of high-quality, easy-to-watch videos on the concepts.
The videos focus mainly on mechanical and structural engineering and contain excellent animations and just enough math to give you a basic understanding. There are 22 videos so far and cover a wide variety of topics, including FEA analysis, stress and strain, aerodynamics, and Young’s modulus. Each video starts with the basics, then digs down into the topic, all the while visualizing the subject being discussed. For example, for FEA he starts with the applications, then covers discretization (meshing) and how to solve the calculations.
For more excellent educational videos, check out [Real Engineering] and [Practical Engineering]. Continue reading “Learn Engineering Concepts With Some Cool Animations”
We have to admire a YouTube channel with the name [Less Boring Lectures]. After all, he isn’t promising they won’t be boring, just less boring. Actually though, we found quite a few of the videos pretty interesting and not boring at all. The channel features videos about mechanical engineering and related subjects like statics and math. While your typical electronics project doesn’t always need that kind of knowledge, some of them do and the mental exercise is good for you regardless. A case in point: spend seven minutes and learn about 2D and 3D vectors in two short videos (see below). Or spend 11 minutes and do the whole vector video in one gulp.
These reminded us of Kahn Academy videos, although the topics are pretty hardcore. For example, if you want to know about axial loading, shear strain, or free body diagrams, this is a good place to look.
Continue reading “Engineering The Less Boring Way”
The name Rube Goldberg has long been synonymous with any overly-built contraption played for laughs that solves a simple problem through complicated means. But it might surprise you to learn that the man himself was not an engineer or inventor by trade — at least, not for long. Rube’s father was adamant that he become an engineer and so he got himself an engineering degree and a job with the city. Rube lasted six months engineering San Francisco’s sewer systems before quitting to pursue his true passion: cartooning.
Rube’s most famous cartoons — the contraptions that quickly became his legacy — were a tongue-in-cheek critique meant to satirize the tendency of technology to complicate our lives in its quest to simplify them. Interestingly, a few other countries have their own version of Rube Goldberg. In the UK it’s Heath Robinson, and in Denmark it’s Robert Storm Petersen, aka Storm P.
Rube Goldberg was a living legend who loved to poke fun at everything happening in the world around him. He became a household name early in his cartooning career, and was soon famous enough to endorse everything from cough drops to cigarettes. By 1931, Rube’s name was in the Merriam-Webster dictionary, his legacy forever cemented as the inventor of complicated machinery designed to perform simple tasks. As one historian put it, Rube’s influence on culture is hard to overstate.
Continue reading “Rube Goldberg’s Least Complicated Invention Was His Cartooning Career”
I was reading Joshua Vasquez’s marvelous piece on the capstan equation this week. It’s a short, practical introduction to a single equation that, unless you’re doing something very strange, covers everything you need to know about friction when designing something with a rope or a cable that has to turn a corner or navigate a wiggle. Think of a bike cable or, in Joshua’s case, a moveable dragon-head Chomper. Turns out, there’s math for that! Continue reading “Run The Math, Or Try It Out?”
I fell in love with cable driven mechanisms a few years ago and put together some of my first mechanical tentacles to celebrate. But only after playing with them did I start to understand the principles that made them work. Today I want to share one of the most important equations to keep in mind when designing any device that involves cables, the capstan equation. Let some caffeine kick in and stick with me over the next few minutes to get a sense of how it works, how it affects the overall friction in your system, and how you can put it to work for you in special cases.
A Quick Refresher: Push-Pull Cable Driven Mechanisms
But first: just what exactly are cable driven mechanisms? It turns out that this term refers to a huge class of mechanisms, so we’ll limit our scope just to push-pull cable actuation systems.
These are devices where cables are used as actuators. By sending these cables through a flexible conduit, they serve a similar function to the tendons in our body that actuate our fingers. When designing these, we generally assume that the cables are both flexible and do not stretch when put in tension. Continue reading “Cable Mechanism Maths: Designing Against The Capstan Equation”