Building a Ranque-Hilsch vortex cooling tube

The Ranque-Hilsch vortex tube is an interesting piece of equipment. It can, without any moving parts or chemicals, separate hot and cold compressed gasses that are passed through it. Interestingly enough, you can cobble one together with very few parts for fairly cheap. [Otto Belden] tossed one together in a weekend back in 2009 just to see if he could do it. His results were fairly good and he shared some video tutorials on its construction.

His latest version, which you can see in the video below, takes compressed air at about 78degrees and spits out about 112degrees on the hot side and  8degrees on the cold side. Not too bad!

Continue reading “Building a Ranque-Hilsch vortex cooling tube”

Helicopter light painting continues to snuff out physics lesson on your brain

Cool picture, huh? Wait until you see the video footage of this LED-adorned RC helicopter flying on a dark night. But this isn’t an art project. Analyzing the long-exposure photography turns out to be a great way of clearing up some of the physics of flight which otherwise are not at all intuitive. The helicopter used here has different colored lights on the nose and tail, as well as lights on the rotors.

Depending on how the aircraft is moving, different 3D spirography is captured by the camera. When you zoom in on part of the flight path it becomes clear that there are wider arcs on one side of the fuselage than there are on the other. This has to do with the forward progress of the aircraft and the rotation of the blades. The phenomenon is well known by helicopter enthusiasts, and accounted for in the design. But what we didn’t realize is that it actually translates to a theoretical speed limit for the aircraft. Our childhood love of Airwolf — the TV helicopter that could outrun jets — has been deflated.

You should remember the helicopter physics videos featured here last month. This is the latest offering and we’re still wanting more!

Continue reading “Helicopter light painting continues to snuff out physics lesson on your brain”

(Model) Helicopter Physics

sideways helicopter

If you’ve ever wondered how a helicopter is able to fly, or would just like to see some awesome RC piloting, the four videos after the break should be just the thing! Although the basic physics of how one works is explained in the last three, one would still be hard pressed to explain how [Carl] is able to fly his RC helo the way he does. The video has to be seen to be believed or even explained, but one of the simpler tricks involved taking off a few feet, doing a forward flip, and flying off backwards and upside-down!

As explained in detail in the other videos, a helicopter is controlled by something called a swash plate on the main rotor, which in short translates a linear action into a rotational one. The same thing is done with the tail rotor, but you’ll have to check out the videos after the break for a full explanation! Really ingenious that someone could come up with this analog control system to use before computers were available.

Of particular interest to physics geeks, an explanation of gyroscopic precession is given in the fourth video. Controlling a helicopter may not work exactly the way you thought!

Continue reading “(Model) Helicopter Physics”

Marble machines roundup

[Denha’s] been building marble machines for years and decided to look a back on some of his favorite marble-based builds  (translated). There’s a slew of them, as well as some thoughts about each. Our favorite part is the digital simulations of the projects. For instance, the image above shows a flip-flop marble machine that was built in a physics simulator. This makes it a lot easier to plan for the physical build as it will tell you exact dimensions before you cut your first piece of material. Both of these images were pulled from videos which can be seen after the break. But this isn’t the most hard-core of pre-build planning. SolidWorks, a CAD suite that is most often used to design 3D models for precision machining, has also been used to model the more intricate machines.

Continue reading “Marble machines roundup”

Old Computer Parts Demonstrate How Particle Accelerators Work

[Ameres Valentin] writes in to let us know about his DIY particle accelerator model. The model, made mostly out of old computer stuff, mimics a linear high-energy particle accelerator which use drift tubes to toss particles around. Drift tubes work by first attracting a particle (in this case, ball bearing) until it crosses a charged plate (in this case, coil), then flipping the charge polarity and repelling the particle.  In this case the accelerators function more like a multiple coil gun, as they can’t exactly push the bearing away. Regardless of the specifics the model is an excellent visual aid.

As the bearing rolls along the rails of the CD spindle it shorts bits of foil tape placed just ahead of the magnets. This (appears) to flip a relay that switches on the magnet. Once the magnet coil is energized it pulls the bearing towards its center, accelerating it. The foil stops just before the point where the magnet would pull back the bearing. We are not sure if [Ameres] is using any trickery to get the magnets to individually power, as schematics are not available. The circuit should be simple enough to figure out with a couple relays. In the video [Ameres] adds a lamp to the coils to display when they are powered. Nice work! This could make a fun distraction desk accessory, better than those clicky Newton’s cradles.

Check out [Ameres]’ site for a video of the model in action.

The basics of building a multitouch table

Here is a bare-bones multitouch table setup. We looked in on [Seth Sandler’s] multitouch work a few years ago when he completed the MTmini build. He’s scaling up the size a bit with the MTbiggie, and showing you how easy it is to put together. The demo rig seen above is just a couple of chairs, a sheet of acrylic, a mirror, a projector, a computer, and a diy infrared webcam.

The rig uses ambient infrared light to detect the outlines of your fingers when they touch the acrylic surface. A webcam with an exposed camera film filter feeds an image of the infrared light received below the surface to the computer. The incoming video is processed using Community Core Vision, where each individual point is isolated and mapped. Once the data is available the sky’s the limit on what you can develop. [Seth’s] demo packages include a mouse driver, some physics applications, an Angry Birds implementation, and a few others. See for yourself in the video after the break.

Continue reading “The basics of building a multitouch table”

Super refined Kinect physics demo


Since the Kinect has become so popular among hackers, [Brad Simpson] over at IDEO Labs finally purchased one for their office and immediately got to tinkering. In about 2-3 hours time, he put together a pretty cool physics demo showing off some of the Kinect’s abilities.

Rather than using rough skeleton measurements like most hacks we have seen, he paid careful attention to the software side of things. Starting off using the Kinect’s full resolution (something not everybody does) [Brad] took the data and manipulated it quite a bit before creating the video embedded below. Skeleton data was collected and run through several iterations of a smoothing algorithm to substantially reduce the noise surrounding the resulting outline.

The final product is quite a bit different than the Kinect videos we are used to seeing, and it drastically improves how the user is able to interact with virtual objects added to the environment. As you may have noticed, the blocks that were added to the video never rarely penetrate the outline of the individual in the movie. This isn’t due to some sort of digital trickery – [Brad] was able to prevent the intersection of different objects via his tweaking of the Kinect data feed.

We’re not sure how much computing power this whole setup requires, but the code is available from their Google Code repository, so we hope to see other projects refined by utilizing the techniques shown off here.

[via KinectHacks]

Continue reading “Super refined Kinect physics demo”