Tomatoes Are Not Guncotton

[Integza] hates tomatoes, but loves rocketry. Thus, he decided to see if he could process his most-loathed fruit into some sort of rocket fuel, or at least something relatively flammable. The experiment ended poorly, but the science behind it is interesting.

The basic idea is that tomatoes are largely made up of water, sugar, and cellulose. Thus, if you nitrate that cellulose, it becomes nitrocellulose, also known as guncotton. Guncotton is was once used to replace gunpowder in firearms, though today it’s often used by magicians to create ashless flashes of flame.

To achieve this, [Integza] first attempted to make regular guncotton using a 50:50 mixture of nitric acid and sulfuric acid. The cotton was then neutralized with a baking soda and water mixture to remove excess acid, and the cotton dried. Once tested, it burned quickly as you’d expect from guncotton.

After removing the sugars from tomatoes with water, soap, hydrogen peroxide, and bleach, the tomatoes were then dried to remove excess water before also getting the acid treatment. They were then similarly neutralized, dried, and tested. One tomato did burn rather quickly, while the others merely fizzled.

One of the reasons behind this may have been due to the composition of the tomatoes. Tomatoes often consist of a mixture of cellulose, hemicellulose, and lignin, these latter components are known for producing inferior guncotton. The ramshackle preparation may have had some effect on the results. Let’s just say and it’s not advisable to work with fuming acids without protective gear and a fume hood, either.

The video’s title claims that the tomatoes were turned into rocket fuel, which is far beyond the actual results of the experiment. However, with some more advanced chemical processing, we could certainly see the fruit becoming a mite more flammable than it was. You’re probably better off just sticking to straight cotton though, for the best results. Video after the break.

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30 Days Of Terror: The Logistics Of Launching The James Webb Space Telescope

Back during the 2019 Superconference in Pasadena, I had the chance to go to Northrop Grumman’s Redondo Beach campus to get a look at the James Webb Space Telescope. There is the high-bay class 10,000+ cleanroom in building M8, my wife and I along with fellow space nerd Tom Nardi got a chance to look upon what is likely the most expensive single object ever made. The $10 billion dollar space observatory was undergoing what we thought were its final tests before being packaged up and sent on its way to its forever home at the L2 Lagrange point.

Sadly, thanks to technical difficulties and the COVID-19 pandemic, it would be another two years before JWST was actually ready to ship — not a new story for the project, Mike Szczys toured the same facility back in 2015. But the good news is that it finally has shipped, taking the very, very slow first steps on its journey to space.

Both the terrestrial leg of the trip and the trip through 1.5 million kilometers of space are fraught with peril, of a different kind, of course, but still with plenty of chances for mission-impacting events. Here’s a look at what the priceless and long-awaited observatory will face along the way, and how its minders will endure the “30 days of terror” that lie ahead.

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Building A Water Rocket That Lands Via Parachute

Water rockets are plenty of fun, but they can be even more fun if you go wild with the engineering. [The Q] is one such experimenter, who built a dual-thrust water rocket that even has a parachute for landing!

The testing took place in an area strangely reminiscent of a certain operating system.

The dual-thrust concept is an interesting one, and is well explained by fellow YouTube channel [Air Command Rockets]. The basic idea is to use several chambers on the water rocket, one which provides an initial short “boost” phase of high acceleration, followed by a longer “sustain” level of acceleration from a secondary chamber.

It’s a great way to send a water rocket ever higher, but [The Q] didn’t stop there. The build was also fitted with a wind-up module from a little walking toy, colloquially referred to as a “Tomy timer” in the water rocket scene. A rubber band is wound around the timer’s output shaft, holding a door shut containing a parachute. At launch, the windup mechanism is released, and its output shaft turns, eventually releasing the parachute. The trick is setting up the timer to release the chute just after the rocket is done with its thrust phase.

It’s a neat build, and one that would serve as a great guide to those eager to start their own journey down the rabbit hole of advanced water rockets. We’ve seen similar work before, too. Video after break.

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Building A Devil’s Toothpaste Rocket Motor

When it comes to weird and wacky homebrew rocket experiments, [Integza] keeps himself fairly busy. He’s now attempted a design repurposing Devil’s Toothpaste for propulsion.

Devil’s Toothpaste is really the same as the famous Elephant Toothpaste experiment, just executed with higher concentration hydrogen peroxide. In this case, [Integza] is using 50% hydrogen peroxide combined with potassium permanganate as a catalyst. When the two are combined, the hydrogen peroxide breaks down into oxygen and water, which [Integza] uses here to propel a skateboard.

The potassium permanganate catalyst is impregnated into 3D printed porous ceramic parts. The peroxide is thenĀ  injected into this matrix via a compressed air mechanism, where it decomposes, creating a jet of water and oxygen that then blasts out of a 3D printed rocket nozzle to generate thrust.

It works surprisingly well, even if it’s a messy and unconventional way to build a rocket. It’s also a lot less fiery than most of [Integza]’s previous projects. Video after the break.

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3D printed rocket laying on grass

3D Printed Rocket’s Features Are Out Of This World

We’re delighted to see the progress on [Foaly]’s 3D-printed Cortex 2 rocket, and the latest build log is full of beautiful pictures and design details. Not only is this rocket jam-packed with an efficiency of electronics and smart design, but it almost seems out to single-handedly prove that 3D-printing is far from the novelty some think it is.

Electronics and wires packing the fuselage of a model rocket
Cable management and component layout is far from a trivial task in a rocket like this.

There is so much going on in the Cortex 2 that it simply wouldn’t be possible to do everything it does without the ability to make one’s own parts exactly to specification. In fact, there is so much going on that cable management is its own challenge.

Everything in the build log is interesting, but the design of the parachute system is of particular note. [Foaly]’s original Cortex rocket met it’s end when the parachute failed to deploy, and Cortex 2 is determined to avoid that fate if it can. For the parachute and any cords and anchors, a careful layout maximizes the chances of a successful deployment without anything tangling, but there are some extra features as well. The panel covering the parachute is mounted with the help of four magnets, which are mounted with opposing polarities. This provides an initial repulsing force when the door is unlocked by a servo, which should help wind immediately rush in to the opening to blow the panel away. The recovery system even has its own dedicated microcontroller and can operate autonomously; even if software for everything else crashes, the parachute will still get deployed. Locking connectors for all cables also ensure that acceleration forces don’t dislodge any contacts.

Everything about the rocket looks great, and the amount of work that has gone into the software is particularly evident. The main controller even has an interactive pre-flight checklist, which is a fantastic feature.

The last time we saw the Cortex 2 it was still only about half built, and we can’t wait to see how it performs. Rocketry is a field that has benefited greatly from things like 3D printing, the availability of highly-integrated electronics, and even such things as a rocket design workbench for FreeCAD. Better tools enable better work, after all.

Three-Stage Thrust Vectoring Model Rocket With Tiny Flight Computers

Flying a thrust-vectoring rocket can be a challenge, and even more so if you stack multiple stages and a minimalist flight computer on top of it all. But [Joe Barnard] is not one to shy away from such a challenge, so he built a three stage actively guided rocket named Shreeek.

[Joe] is well known for his thrust-vectoring rockets, some of which have came within a hair’s breadth of making a perfect powered landing. Previous rockets have used larger, more complex flight computers, but for this round, he wanted to go as small and minimalist as possible. Each stage of the rocket has its own tiny 16 x 17 mm flight computer and battery. The main components are a SAM21 microcontroller running Arduino firmware, an IMU for altitude and orientation sensing, and a FET to trigger the rocket motor igniter. It also has servo outputs for thrust vector control (TVC), and motor control output for the reaction wheel on the third stage for roll control. To keep it simple he omitted a way to log flight data, a decision he later regretted. Shreeek did not have a dedicated recovery system on any of the stages, instead relying on its light weight and high drag to land intact

None of the four launch attempts went as planned, with only the first two stages functioning correctly in the test with the best results. Thanks to the lack of recorded flight data, [Joe] had to rely on video footage alone to diagnose the problems after each launch. Even so, his experience diagnosing problems certainly proved its worth, with definitive improvements. However, we suspect that all his future flight computers will have data logging features included.

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Image of detonation engine firing

Japanese Rocket Engine Explodes: Continuously And On Purpose

Liquid-fuelled rocket engine design has largely followed a simple template since the development of the German V-2 rocket in the middle of World War 2. Propellant and oxidizer are mixed in a combustion chamber, creating a mixture of hot gases at high pressure that very much wish to leave out the back of the rocket, generating thrust.

However, the Japan Aerospace Exploration Agency (JAXA) has recently completed a successful test of a different type of rocket, known as a rotating detonation engine. The engine relies on an entirely different method of combustion, with the aim to produce more thrust from less fuel. We’ll dive into how it works, and how the Japanese test bodes for the future of this technology.

Deflagration vs. Detonation

Humans love combusting fuels in order to do useful work. Thus far in our history, whether we look at steam engines, gasoline engines, or even rocket engines, all these technologies have had one thing in common: they all rely on fuel that burns in a deflagration. It’s the easily controlled manner of slow combustion that we’re all familiar with since we started sitting around campfires. Continue reading “Japanese Rocket Engine Explodes: Continuously And On Purpose”