Desktop Wind Tunnel Brings Aerospace Engineering To The Home Gamer

November 20, 2020 by Mike Szczys 10 Comments

Computer simulation is indispensable in validating design and used in every aspect of engineering from finite element analysis to traffic simulation to fluid dynamics. Simulations do an amazing job and at a fraction of the time and expense of building and testing a scale model. But those visceral ah-ha moments, and some real-world gremlins, can be easier to uncover by the real thing. Now you don’t need a university research or megacorp lab to run aerodynamic study IRL, you can just build a functional desktop wind tunnel for a pittance.

[Mark Waller] shows off this tidy little design that takes up only about two feet of desk space, and includes the core features that make a wind tunnel useful. Air is pulled through the tunnel using a fan mounted at the exhaust side of the tunnel. The intake is the horn-like scoop, and he’s stacked up a matrix of drinking straws there to help ensure laminar flow of the air as it enters the tunnel. (The straw trick is frequently used with laminar flow water fountains). It also passes through a matrix of tubes about the diameter of a finger at the exhaust to prevent the spin of the fan from introducing a vortex into the flow.

For analysis, five tubes pipe in smoke from an vape pen, driven into the chamber by an aquarium pump. There’s a strip of LEDs along the roof of the tunnel, with a baffle to prevent the light shining on the black rear wall of the chamber for the best possible contrast. The slow-motion video after the break shows the effectiveness of the setup.

Whether you’re a Hackaday Editor cutting their own glider wing profiles using foam and hot wire, or just want to wrap your head around how different profiles perform, this will get you there. And it’ll do it at a fraction of the size that we’ve seen in previous wind tunnel builds.

Continue reading “Desktop Wind Tunnel Brings Aerospace Engineering To The Home Gamer” →

Ask Hackaday: What Tools Do You Really Need For A Life On The Road?

November 20, 2020 by Jenny List 45 Comments

How do you dispose of an old hard drive? Inventive stories about heat and flame or industrial shredders will no doubt appear in the comments, but for me I just dismantle them and throw the various parts into the relevant scrap bins at my hackerspace. The magnets end up stuck to a metal door frame, and I’m good to go. So a week or so ago when I had a few ancient drives from the 1990s to deal with, I sat down only to find my set of Torx and Allen drivers was missing. I was back to square one.

What A Missing Tool Tells You About Necessities

Clint Eastwood always seemed to have just what he needed, why can I never manage it! Produzioni Europee Associati, Public domain.

Life deals an odd hand, sometimes. One never expects to find oneself homeless and sofa-surfing, nearly all possessions in a container on a farm somewhere. But here I am, and somewhere in one of those huge blue plastic removal crates is my driver set, alongside the other detritus of an engineer scribe’s existence. It’s all very well to become a digital nomad with laptop and hotspot when it comes to writing, but what has the experience taught me about doing the same as a solderer of fortune when it comes to hardware? My bench takes up several large removal crates and there is little chance of my carrying that much stuff around with me, so what makes the cut? Evidently not the tools for hard drive evisceration, so I had to borrow the set of a hackerspace friend to get the job done. Continue reading “Ask Hackaday: What Tools Do You Really Need For A Life On The Road?” →

Hackaday Podcast 094: Fake Sun, Hacked Super Mario, Minimum Viable Smart Glasses, And 3D Printers Can’t Do That

November 20, 2020 by Mike Szczys 3 Comments

Hackaday editors Elliot Williams and Mike Szczys traverse the hackerscape looking for the best the internet had to offer last week. Nintendo has released the new Game & Watch handheld and it’s already been hacked to run custom code. Heading into the darkness of winter, this artificial sun build is one not to miss… and a great way to reuse a junk satellite dish. We’ve found a pair of smartglasses that are just our level of dumb. And Tom Nardi cracks open some consumer electronics to find a familiar single-board computer doing “network security”.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~60 MB)

Places to follow Hackaday podcasts:

Continue reading “Hackaday Podcast 094: Fake Sun, Hacked Super Mario, Minimum Viable Smart Glasses, And 3D Printers Can’t Do That” →

New Part Day: Bouffalo Labs BL602 RISC-V Wi-Fi/Bluetooth SoC

November 20, 2020 by Jenny List 20 Comments

We should all by now be used to microcontrollers with wireless hardware on board, with Espressif or Nordic Labs dominating the hacker scene. There have been several other contenders in this arena over the years that haven’t really caught the attention of our community, usually because of the opacity of their available information.

A new contender should be worth a second look though. The BL602 from Bouffalo Labs is a Wi-Fi- and Bluetooth LE-capable microcontroller with a 32-bit RISC-V derived core. If that doesn’t interest you much, perhaps news that the PINE64 folks are spearheading an effort to reverse engineer it for a fully open-source blob-free wireless implementation might sharpen your attention.

So where can you get your hands on one? Hold your horses, this chip is at an early stage in its gestation. We can see that there are some exciting possibilities in store, but we’re still figuring out the hardware interfaces and other software required to make it work. A community is hard at work reverse engineering it, which leads us back to the PINE64 story we mentioned earlier.

You can find BL602 modules from AliExpress vendors, but the PINE64 folks will offer you a free one if you join their blob reverse engineering effort. Take note though, this offer is for those prepared to show commitment to the project, so don’t spam them in the hope of free stuff if you won’t be helping deliver the goods.

We might see the BL602 gaining an open-source toolchain and internal blobs over the coming months thanks to the efforts of those working on it. Just as the ESP8266 did back in 2014, it’s starting as a black box with a relative scarcity of information. But if this hacking effort pays off, we’ll have a cheap RISC-V Wi-Fi and Bluetooth module with entirely open-source software from the silicon upwards. What a time to be alive!

Thanks [Renze] for the tip.

This Week In Security: SAD DNS, Incident Documentation Done Well, And TCL Responds

November 20, 2020 by Jonathan Bennett 6 Comments

One of the big stories from the past few days is the return of DNS cache poisoning. The new attack has been dubbed SADDNS, and the full PDF whitepaper is now available. When you lookup a website’s IP address in a poisoned cache, you get the wrong IP address.

This can send you somewhere malicious, or worse. The paper points out that DNS has suffered a sort of feature creep, picking up more and more responsibilities. The most notable use of DNS that comes to mind is LetsEncrypt using DNS as the mechanism to prove domain ownership, and issue HTTPS certificates.

DNS Cache poisoning is a relatively old attack, dating from 1993. The first iteration of the attack was simple. An attacker that controlled an authoritative DNS server could include extra DNS results, and those extra results would be cached as if they came from an authoritative server. In 1997 it was realized that the known source port combined with a non-random transaction ID made DNS packet spoofing rather trivial. An attacker simply needs to spoof a DNS response with the appropriate txID, at the appropriate time to trick a requester into thinking it’s valid. Without the extra protections of TCP connections, this was an easy task. The response was to randomize the txID in each connection.

I have to take a moment to talk about one of my favorite gotchas in statistics. The Birthday paradox. The chances that two randomly selected people share a birthday is 1 in 365. How many people have to be in a room together to get a 50% chance of two of them sharing a birthday? If you said 182, then you walked into the paradox. The answer is 23. Why? Because we’re not looking for a specific birthday, we’re just looking for a collision between dates. Each non-matching birthday that walks into the room provides another opportunity for the next one to match.

This is the essence of the DNS birthday attack. An attacker would send a large number of DNS requests, and then immediately send a large number of spoofed responses, guessing random txIDs. Because only one collision is needed to get a poisoned cache, the chances of success go up rapidly. The mitigation was to also randomize the DNS source port, so that spoof attempts had to have both the correct source port and txID in the same attempt. Continue reading “This Week In Security: SAD DNS, Incident Documentation Done Well, And TCL Responds” →

3D Printable Cloth Takes Advantage Of Defects

November 20, 2020 by Al Williams 24 Comments

Normally, a 3D printer that under extrudes is a bad thing. However, MIT has figured out a way to deliberately mix full extrusions with under extruded layers to print structures that behave more like cloth than normal 3D printed items. The mesh-like structure apparently doesn’t require any modification to a normal 3D printer, just different software to create special code sequences to create the material.

Called DefeXtiles, [Jack Forman] is producing sheets and complex structures that appear woven. The process is known as “blob-stretch” because of the way the plastic makes blobs connected by fine filaments of plastic.

Continue reading “3D Printable Cloth Takes Advantage Of Defects” →

Mushroom Canoe Is Rooted In Nature

November 20, 2020 by Kristina Panos 38 Comments

Mushrooms might be the most contested pizza topping after pineapple, but can you build a boat from pineapples? Probably not, but you can from mushrooms. Mushrooms, or rather their mycelium root systems, can be used for things like packaging, insulation, and furniture, and it could be the next thing in floatation, too. Just ask [Katy Ayers], a Nebraska college student who built an eight-foot canoe molded almost entirely of mycelium.

[Katy] got into mushrooms when she was tasked with researching solutions to climate change. She loves to fish and has always wanted a boat, so when she found out that mycelium are naturally buoyant and waterproof, she decided to try using it as a building material.

[Katy] floated the idea by the owner of a local mushroom company and they got to work, building a frame suspended in the air by a hammock-like structure. Then they covered the boat’s skeleton with spores and let it proliferate in a hot, humid growing room. Two weeks later, they had a boat made of live mycelium, which means that every time it goes out on the water, it spawns mushrooms. The total cost including tools was around $500. The boat experiment spawned even more mycelium projects. [Katy] has since experimented with making lawn chairs and landscaping bricks from mycelium.

Don’t want to wait to grow your own mycelium boat? You can build one out of stretch wrap, packing tape, and tree branches.

Thanks for the tip, [ykr300]!

Main image by Katy Ayers via NBC News