Formation Flying Does More Than Look Good

June 26, 2023 by Bryan Cockfield 14 Comments

Seeing airplanes fly in formation is an exciting experience at something like an air show, where demonstrations of a pilot’s skill and aircraft technology are on full display. But there are other reasons for aircraft to fly in formation as well. [Peter] has been exploring the idea that formation flight can also improve efficiency, and has been looking specifically at things like formation flight of UAVs or drones with this flight planning algorithm.

Aircraft flying in formation create vortices around the wing tips, which cause drag. However, another aircraft flying through those vortices will experience less drag and more efficient flight. This is the reason birds instinctively fly in formation as well. By planning paths for drones which will leave from different locations, meet up at some point to fly in a more efficient formation, and then split up close to their destinations, a significant amount of energy can potentially be saved. Continue reading “Formation Flying Does More Than Look Good” →

Optimize Your Paper Planes With This Cardboard Wind Tunnel

March 22, 2023 by Robin Kearey 6 Comments

We at Hackaday are great fans of hands-on classroom projects promoting science, technology, engineering and math (STEM) subjects – after all, inspiring kids with technology at a young age will help ensure a new generation of hardware hackers in the future. If you’re looking for an interesting project to keep a full classroom busy, have a look at [drdonh]’s latest project: a fully-functional wind tunnel made from simple materials.

Built from cardboard, it has all the same components you’d find in a full-size aerodynamics lab: a fan to generate a decent stream of air, an inlet with channels to stabilize the flow, and a platform to mount experiments on. There’s even some basic instrumentation included that can be used to measure drag and lift, allowing the students to evaluate the drag coefficients of different car designs or the lift-generating properties of various airfoils. Continue reading “Optimize Your Paper Planes With This Cardboard Wind Tunnel” →

One Method For Removing Future Space Junk

March 22, 2023 by Bryan Cockfield 18 Comments

When sending satellites into space, the idea is to place them into as stable an orbit as possible in order to maximize both the time the satellite is useful and the economics of sending it there in the first place. This tends to become rather untenable as the amount of space junk continues to pile up for all but the lowest of orbits, but a team at Brown University recently tested a satellite that might help solve this problem, at least for future satellite deployments.

The main test of this satellite was its drag sail, which increases its atmospheric drag significantly and reduces its spaceflight time to around five years. This might make it seem like a problem from an economics standpoint, as it’s quite expensive to build satellites and launch them into space, but this satellite solves these problems by being both extremely small to minimize launch costs, and also by being built out of off-the-shelf components not typically rated for spaceflight. For example, it gets its power solely from AA batteries and uses an Arduino for its operation and other research.

The satellite is currently in orbit, and has already descended from an altitude of 520 km to 470 km. While it won’t help reduce the existing amount of debris in orbit, the research team hopes to demonstrate that small satellites can be affordable and economically feasible without further contributing to the growing problem of space junk. If you’re looking to launch your own CubeSat one day, take a look at this primer which goes over most of the basics.

A Look At The Most Aerodynamic Cars Ever Built

April 20, 2021 by Lewin Day 77 Comments

Whether gasoline, diesel, or electric, automakers work hard to wring every last drop of mileage out of their vehicles. Much of this effort goes towards optimising aerodynamics. The reduction of drag is a major focus for engineers working on the latest high-efficiency models, and has spawned a multitude of innovative designs over the years. We’ll take a look at why reducing drag is so important, and at some of the unique vehicles that have been spawned from these streamlining efforts.

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How To Get Into Cars: Drag Racing Mods

December 17, 2020 by Lewin Day 20 Comments

While some love to carve up mountain roads, and others relish the challenge of perfectly apexing every corner at the track, many crave a different challenge. Drag racing is a sport all about timing, finesse, and brute power. Like any other discipline in motorsport, to compete you’ll need a vehicle finely honed for the task at hand. Here’s how you go about getting started on your first quarter-mile monster.

It’s All About Power, Right?

It’s true that if you want to go faster, having more power on tap is a great way to do it. If that’s what you’re looking for, we’ve covered that topic in detail – for both the naturally aspirated and forced induction fans. However, anyone that’s been to the drag strip before will tell you that’s only part of the story. All of the power in the world isn’t worth jack if you can’t get it down to the ground. Even if you can, you’ve still got to keep your steering wheels planted if you intend to keep your nose out of the wall. So, if you want more power, consider the articles linked above. For everything else that’s important in drag racing, read on below.

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Custom Aluminum Wheels Teach A Thing Or Two About Casting

July 1, 2017 by Dan Maloney 35 Comments

For some mobile projects like small carts or rolling cabinets, your standard casters from Harbor Freight will do just fine. But some projects need big, beefy wheels, and these custom cast aluminum wheels certainly make a statement. Mostly, “Watch your toes!”

To be honest, [Brian Oltrogge]’s wheels are an accessory in search of a project, and won’t be crushing feet anytime soon. He made them just to make them, but we have no beef with that. They’ve got a great look that hearkens back to a time when heavy metal meant something else entirely, and things were made to last. Of course, being cast from aluminum sort of works against that, but there are practical limits to what can be done in the home foundry. [Brian] started with a session of CAD witchcraft followed by machining the cores for his molds. Rather than doing this as lost foam or PLA, he milled the cores from poplar wood. His sand mix is a cut above what we usually see in home-brew sand casting — sodium silicate sand that can be cured with carbon dioxide. All his careful preparation meant the pour went off without a hitch, and the wheels look great.

We’ve featured quite a few metal casting projects recently, some that went well and some that didn’t. [Brian] looks like he knows what he’s doing, and we appreciate the workmanship that he puts on display here.

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Retrotechtacular: Forces Acting On An Airfoil

August 19, 2014 by Kristina Panos 20 Comments

floating film title We’ve probably all experimented with a very clear demonstration of the basic principles of lift: if you’re riding in a car and you put your flattened hand out the window at different angles, your hand will rise and fall like an airplane’s wing, or airfoil. This week’s Retrotechtacular explains exactly how flight is possible through the principles of lift and drag. It’s an Army training documentary from 1941 titled “Aerodynamics: Forces Acting on an Air Foil“.

What is an airfoil? Contextually speaking, it’s the shape of an airplane’s wing. In the face of pressure differences acting upon their surfaces, airfoils produce a useful aerodynamic reaction, such as the lift that makes flight possible. As the film explains, the ideas of lift and drag are measured against the yardstick of relative wind. The force of this wind on the airfoil changes according to the acute angle formed between the airfoil and the direction of the air flow acting upon it. As you may already know, lift is measured at right angles to the relative wind, and drag occurs parallel to it. Lift is opposed by the weight of the foil, and drag by tension.

wind tunnel testing

Airfoils come in several types of thicknesses and curvatures, and the film shows how a chord is derived from each shape. These chords are used to measure and describe the angle of attack in relation to the relative wind.

The forces that act upon an airfoil are measured in wind tunnels which provide straight and predictable airflow. A model airplane is supported by wires that lead to scales. These scales measure drag as well as front and rear lift.

In experimenting with angles of attack, lift and drag increase toward what is known as the stalling angle. After this point, lift decreases abruptly, and drag takes over. Lift and drag are proportional to the area of the wing, the relative wind velocity squared, and the air density. When a plane is in the air, drag is a retarding force that equals the thrust of the craft, or the propelling force.

monometer tubes Airfoil models are also unit tested in wind tunnels. They are built with small tubes running along many points of the foil that sit just under the surface. The tubes leave the model at a single point and are connected to a bank of manometer tubes. These tubes compare the pressures acting on the airfoil model to the reference point of atmospheric pressure. The different liquid levels in the manometer tubes give clear proof of the pressure values along the airfoil. These levels are photographed and mapped to a pressure curve. Now, a diagram can be made to show the positive and negative pressures relative to the angle of attack.

In closing, we are shown the effects of a dive on lift as an aircraft approaches and reaches terminal velocity, and that lift is attained again by pulling slowly out of the dive. Remember that the next time you fly your hand-plane out the window.

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