3D Printing May Be The Key To Practical Scramjets

The first scramjet, an airbreathing jet engine capable of pushing an aircraft beyond Mach 5, was successfully flown in the early 1990s. But while pretty much any other technology you could imagine has progressed by leaps and bounds in the nearly 30 years that have passed, the state-of-the-art in hypersonic scramjets hasn’t moved much. We still don’t have practical hypersonic aircraft, military or otherwise, and any missiles that travel at those sort of speeds are rocket powered.

NASA’s X-43 hit Mach 9.6 in 2004

This is somewhat surprising since, at least on paper, the operating principle of the scramjet is simplicity itself. Air rushing into the engine is compressed by the geometry of the inlet, fuel is added, the mixture is ignited, and the resulting flow of expanded gases leaves the engine faster than it entered. There aren’t even any moving parts inside of a scramjet, it’s little more than a carefully shaped tube with fuel injectors and ignitors in it.

Unfortunately, pulling it off in practice is quite a bit harder. Part of the problem is that a scramjet doesn’t actually start working until the air entering the engine’s inlet is moving at around Mach 4, which makes testing them difficult and expensive. It’s possible to do it in a specially designed wind tunnel, but practically speaking, it ends up being easier to mount the engine to the front of a conventional rocket and get it up to speed that way. The downside is that such flights are one-way tickets, and end with the test article crashing into the ocean once it runs out of fuel.

But the bigger problem is that the core concept is deceptively simple. It’s easy to say you’ll just squirt some jet fuel into the stream of compressed air and light it up, but when that air is moving at thousands of miles per hour, keeping it burning is no small feat. Because of this, the operation of a scramjet has often been likened to trying to light a match in a hurricane; the challenge isn’t in the task, but in the environment you’re trying to perform it in.

Now, both Aerojet Rocketdyne and Northrop Grumman think they may have found the solution: additive manufacturing. By 3D printing their scramjet engines, they can not only iterate through design revisions faster, but produce them far cheaper than they’ve been able to in the past. Even more importantly, it enables complex internal engine geometries that would have been more difficult to produce via traditional manufacturing.

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Go Subterranean With This DARPA Challenge

Whether it comes to rescuing people from a cave system or the underground maze of sewers, tunnels and the like that exist underneath any major city, having accurate maps of the area is always crucial to know what the optimal routes are, and what the expected dangers are. The same is true for combat situations, where such maps can mean the difference between the failure or success of a mission. This is why DARPA last year started the Subterranean Challenge, or ‘SubT’ for short.

This challenge seeks new approaches to map, navigate, and search underground environments during time-sensitive combat operations or disaster response scenarios, which would allow for these maps to be created on-demand, in the shortest amount of time possible. Multidisciplinary teams from the world are invited to create autonomous systems that can map such subsurface networks no matter the circumstances.

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DARPA Goes Underground For Next Challenge

We all love reading about creative problem-solving work done by competitors in past DARPA robotic challenges. Some of us even have ambition to join the fray and compete first-hand instead of just reading about them after the fact. If this describes you, step on up to the DARPA Subterranean Challenge.

Following up on past challenges to build autonomous vehicles and humanoid robots, DARPA now wants to focus collective brainpower solving problems encountered by robots working underground. There will be two competition tracks: the Systems Track is what we’ve come to expect, where teams build both the hardware and software of robots tackling the competition course. But there will also be a Virtual Track, opening up the challenge to those without resources to build big expensive physical robots. Competitors on the virtual track will run their competition course in the Gazebo robot simulation environment. This is similar to the NASA Space Robotics Challenge, where algorithms competed to run a virtual robot through tasks in a simulated Mars base. The virtual environment makes the competition accessible for people without machine shops or big budgets. The winner of NASA SRC was, in fact, a one-person team.

Back on the topic of the upcoming DARPA challenge: each track will involve three sub-domains. Each of these have civilian applications in exploration, infrastructure maintenance, and disaster relief as well as the obvious military applications.

  • Man-made tunnel systems
  • Urban underground
  • Natural cave networks

There will be a preliminary circuit competition for each, spaced roughly six months apart, to help teams get warmed up one environment at a time. But for the final event in Fall of 2021, the challenge course will integrate all three types.

More details will be released on Competitor’s Day, taking place September 27th 2018. Registration for the event just opened on August 15th. Best of luck to all the teams! And just like we did for past challenges, we will excitedly follow progress. (And have a good-natured laugh at fails.)

DARPA Enlisting Nemo And Dory To Find You

The ocean is a hostile environment for man-made equipment, no matter its purpose. Whether commercial fishing, scientific research, or military operations, salt water is constantly working to break them all down. The ocean is also home to organisms well-adapted to their environment so DARPA is curious if we can leverage their innate ability to survive. The Persistent Aquatic Living Sensors (yes, our ocean PALS) program is asking for creative ideas on how to use sea life to monitor ocean activity.

Its basic idea is simple: everyday business of life in the ocean are occasionally interrupted by a ship, a submarine, or some other human activity. If this interruption can be inferred from sea life response, getting that data could be much less expensive than building sensors to monitor such activity directly. Everyone who applies to this research program will have the chance to present their own ideas on how to turn this idea into reality.

The program announced it will “study natural and modified organisms” (emphasis ours.) Keeping an open mind to bio-engineering ideas will be interesting, but adding biohacking to the equation also adds to the list of potential problems. While PALS will keep its research within contained facilities, any future military deployment obviously will not. Successful developments in this area will certainly raise eyebrows and face resistance against moving beyond the lab.

But such possibilities are still far away in a future that many never arrive, as is common with DARPA initiatives. Very recently we talked about their interest in brain stimulation and we’ve been fascinated by many DARPA initiatives before that. If PALS takes off, their living sensor nodes might end up face to face with the open-source underwater glider project that won this year’s Hackaday prize.

[via Engadget]

Hackaday Links: May 28, 2017

Boeing and DARPA are building a spaceplane. Right now it’s only a press release and a few concept images, but it looks like this is an air-launched system kind of like a Tristar/Pegasus, only much higher and completely unmanned. It’s a ton and a half to low earth orbit, with a goal of 10 flights in 10 days.

Up in Albany? There’s a new hacker con happening in a few weeks. Anycon is a hacking, infosec, and cyber security conference happening June 16 & 17th in Albany, NY. The organizers of this con ([Chris], and his company Leet Cybersecurity) are loosely modeling this con after Derbycon. [Dave Kennedy] of TrustedSec will be attending as the keynote speaker.

GOOD NEWS! [Casey Neistat] is under investigation by the FAA. [Casey Neistat] is the YouTuber that flies drones right in the middle of the Hudson River corridor, and is a menace to general aviation around NYC.

This is neat. The Supplyframe Design Lab is the Hackaday Mothership right in the middle of Pasadena where we host our designers in residence, host a few meetups, and slowly fill every cubic inch of space with either dust or tools. The Design Lab just won a design award. You can check out the ‘design’ part of the Design Lab here, but keep in mind it will never be that clean ever again.

Here’s an interesting Twitter to follow. Alitronik is a curator of the weird and wonderful cheap crap that can be found on AliExpress. Need an Altera Cyclone dev board? Here you go. A desk-mountable OLED inspection microscope? Done. A seven dollar Tesla coil? Dude, you can totally fit this inside a hat.

[Drygol] had a nice old Commodore C16 with a broken TED chip. A shame, really. He did what anyone would do: put a C64 motherboard in the case for a fancy stealth upgrade.

Is the great crowdfunded 3D printer boom over? Some would say that ship sailed after dozens of 3D printer crowdfunding projects failed to deliver, or delivered very low-quality machines. These people were wrong. This Polaroid-branded 3D printing pen might not get funding. A year ago, this project would have been funded on day one. There would have been writeups in The Verge on how Polaroid is turning the corner after decades of wasted opportunities. Now, the Crowdfunded 3D printer boom is finally over.

The Hackaday crew was at the Bay Area Maker Faire last weekend and holy crap did we have a blast. Everyone came to the meetup on Saturday except for the fire marshall. The secret OSHPark bringahack on Sunday was even more impressive. We also saw a Donkey Car capable of driving around a track autonomously, but the team behind it didn’t have their work up on the Internet at the time.

DARPA Plans To Begin Hacking Human Brains

So [DARPA] wants to start hacking human brains, With the help of the biomedical device center at the university of Texas in Dallas. This does sound a bit crazy but DARPA does crazy. Conspiracy theorists are going to have a field day with this one.

The initial plans to turn us all into mindless zombies seem to be shelved for now, however they are working on what they call Targeted Neuroplasticity Training (TNT), which they explain means using the body’s nervous system to enhance and speed up the learning process. This could be achieved by using a process known as ‘synaptic plasticity‘ which opens and closes the brains synapses with electrical stimulation. They hope that by tuning the neural networks responsible for cognitive function it will enhance learning. Let’s just hope they don’t turn any humans into DARPA falling robots.

Gremlins Are Air To Air Drones

If you are like most people, your drone flights start on the ground and end either on the ground or–in more cases than most of us want to admit–in a tree. Earlier this year, DARPA awarded initial contracts for the Gremlins program. The idea is to produce unmanned aircraft that can launch from another aircraft and then later have another aircraft recover it.

The idea is to allow a plane to launch an unmanned sensor, for example, while out of range of enemy fire. Later another aircraft can retrieve the drone where a ground crew would get it ready for another flight within 24 hours. An aircraft facing missile fire could unleash a swarm of drones, confusing attackers. The drones have a limited life of about twenty flights, allowing for inexpensive airframes that use existing technology. You can see a concept video from DARPA about how air-launched drones might play a role in future air combat below.

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