BPS.Space Succesfully Lands A Model Rocket

If you’ve been following [Joe Barnard]’s rocketry projects for the past few years, you’ll know that one of his primary goals has been to propulsively land a model rocket like SpaceX. Now, 7 years into the rollercoaster journey, he has finally achieved that goal with the latest version of his Scout rocket.

Rocket touching down
We have touchdown!

Many things need to come together to launch AND land a rocket on standard hobby-grade solid fuel rocket motors. A core component is stabilization of the rocket during the entire flight, which achieved using a thrust-vectoring control (TVC) mount for the rocket motors and a custom flight computer loaded with carefully tuned guidance software. Until recently, the TVC mounts were 3D printed, but [Joe] upgraded it to machined aluminum to eliminate as much flex and play as possible.

Since solid-fuel rockets can’t technically be throttled, [Joe] originally tried to time the ignition time of the descent motor in such a manner that it would burn out as the rocket touches down. The ignition time and exact thrust numbers simply weren’t repeatable enough, so in his 2020 landing attempts, he achieved some throttling effect by oscillating the TVC side to side, reducing the vertical thrust component. This eventually gave way to the final solution, a pair of ceramic pincers which block the thrust of the motors as required.

Another interesting component is the landing legs. Made from light carbon fiber rods, they are released by melting a rubber band with nichrome wire and fold into place under spring tension. They also had to be carefully refined to absorb as much impact as possible without bouncing, which killed a few previous landing attempts.

Scrolling back through [Joe]’s videos and seeing the progress in his engineering is absolutely inspiring, and we look forward to his future plans. These include a functional scale model of the belly-flopping starship, a mysterious “meat rocket”, and the big one, a space shot to exceed 100 km altitude.

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From Table to Orbit: Salt

Saving Martian Colonists Using Table Salt And Rocket Science

Imagine for a moment that you are a member of an early Mars colony. You’re stranded, and the only way to get a message home is to launch a radio well above the surface. To make matters worse, you’ve got no rockets! It was this thought experiment that has motivated [Thoisoi2] to experiment with making a rocket motor using only ingredients and methods available to your average Martian colonist. The methods he has chosen can be seen in the video below the break.

If you skipped Rocketry 101, a quick refresher might help: Rockets work by burning a fuel in an enclosed chamber and then expelling it at high speed in one direction. To get the fuel to burn more quickly (and therefore adding more oomph to the angry end) a complement to the fuel called an Oxidizer is added. It serves to create an oxygen rich environment for the fuel to burn in. It’s the same reason a oxy-propane torch burns hotter than propane by itself.

Sugar Fuels Go Boom
The Sugar Powered Rocket Motor says “Boom!”

Firstly, a stranded Martian would need rocket fuel. If you recall the 1999 movie October Sky, four high school kids used table sugar as their fuel. You might also recall that those tended to get all explody. This volatility caused [Thoisoi2] to eschew sugar as a fuel in favor of a fuel that would also be available to any Martian colonist but be far less likely to cause Rapid Unplanned Disassembly.

What about the oxidizer? In October Sky, the boys experimented with Potassium Chlorate. This is commonly used in rockets but may be more difficult to obtain for your average Mars colonist. But, it turns out that Potassium Chlorate and Sodium Chlorate which can be prepared from table salt will work equally. It’s quite a bit more involved than that however.

Simply adding salt and fuel does not a rocket motor make. The nuances, the science, and the chemistry are all laid out in the wonderful video that [Thoisoi2] has put together, and we are sure you’ll enjoy it as much as we did.

You’ll also get to find out if our stranded Martian ever makes it home or if his potato farming was for naught.

We’d also like to echo the warning in the video: This is an experiment that is pretty dangerous, so don’t try this at home! Definitely try it at somebody else’s house first. Or on the surface of Mars.

Recently Hackaday covered another great attempt at making a rocket motor at home, although this one was a bit less successful, but every bit as interesting! Continue reading “Saving Martian Colonists Using Table Salt And Rocket Science”

A Promising Start For The Doritos Space Program

Rocketry is tricky stuff, but as long as you’re not trying to get into space, the whole idea can basically be boiled down into a simple concept: if you put enough thrust behind it, anything can fly. At least, for awhile. It’s this basic premise that allows what hobbyists sometimes refer to as “Odd-Rocs” fly; these unusual objects might not be ideal rockets, but put a big enough motor in there, and it’ll get off the pad.

Recently, [concretedog] thought he’d try putting together his own oddball rocket, and set out to modify a Doritos STAX tube for powered flight. There’s plenty of precedent for turning Pringles tubes into rockets, but of course, that’s hardly surprising. After all, what’s a rocket if not a strong and lightweight cylinder? But the rounded triangular shape of the STAX tube promised to be an interesting change of pace. Plus it looked cool, so there’s that.

Turning the snack container into a rocket was actually pretty straightforward. To start with, [concretedog] sketched around the outside of the tube on a piece of paper, and then took a picture of that with his phone. That image was then brought into Inkscape, and turned into a vector file that he could fiddle around with in CAD.

Between the thin plywood cut on his laser and PETG loaded into his 3D printer, he was able to come up with a strong enough motor mount to take an Estes D12-5. He then created some fins to glue on the side, and a triangular nosecone. A simple recovery system was installed, and the whole thing was finished off with a Doritos-appropriate orange and black color scheme.

The unusual shape of the rocket meant simulating its flight characteristics on the computer wouldn’t work without custom software, so [concretedog] had to use the old school method of checking stability by swinging it around in a circle on a string. After trimming it out so it would orient itself properly on the tether, he was fairly sure it would fly straight under power. Sure enough, the video below shows the nacho cheese flavored rocket streaking skyward with impressive speed and stability.

It’s far from the most advanced model rocket we’ve seen recently, but we really appreciate the simplicity of this build. It’s a great reminder that fun doesn’t have to be high-tech, and that by following some basic construction principles, you can knock out a safe park flier rocket on a weekend.

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A Rocket Powered Ejection Seat For Model Aircraft

As radio control planes don’t typically have human pilots onboard, the idea of installing an ejection seat in one is somewhat frivolous. But that doesn’t mean it wouldn’t be a lot of fun, and [James Whomsley] has set his mind to achieving the task.

The build process is an iterative one, with [James] solving problems step-by-step and testing along the way. The first task was to successfully launch a small action figure and his flight seat vertically in a controlled fashion. After a few attempts, a combination of rocket motors and guide rails were settled upon that could achieve the goal. Next up, a drogue parachute system was designed and tested to stabilize the seat at the height of its trajectory. Further work to come involves handling seat separation and getting the action figure safely back to the ground.

While action figures aren’t alive and the ejection seat serves no real emergency purpose, we can imagine it would be a hit at the local flying field – assuming the parachutes don’t get tangled in someone else’s model. For those interested in the real technology, our own [Dan Maloney] did a great piece on the topic. Video after the break.

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A Cheap And Easy GoPro Mount For Model Rocketry

Launching model rockets is fun, but the real meat of the hobby lies in what you do next. Some choose to instrument their rockets or carry other advanced payloads. [seamster] likes to film his flights, and built a nosecone camera package to do so. 

A GoPro is the camera of choice for [seamster]’s missions, with its action cam design making it easy to fire off with a single press of a button. To mount it on the rocket, the nosecone was designed in several sections. The top and bottom pieces are 3D printed, which are matched with a clear plastic cylinder cut from a soda bottle. Inside the cylinder, the GoPro and altimeter hardware are held in place with foam blocks, cut to shape from old floor mats. The rocket’s parachute is attached to the top of the nose cone, which allows the camera to hang in the correct orientation on both the ascent and descent phases of the flight. Check out the high-flying videos created with this setup after the break.

It’s a simple design that [seamster] was able to whip up in Tinkercad in just a few hours, and one that’s easily replicable by the average maker at home. Getting your feet wet with filming your flights has never been easier – we’ve certainly come a long way from shooting on film in the 1970s.

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Cortex 2 Is One Serious 3D Printed Experimental Rocket

Rocketry is wild, and [Foaly] is sharing build and design details of the Cortex 2 mini rocket which is entirely 3D printed. Don’t let that fool you into thinking it is in any way a gimmick; the Cortex 2 is a serious piece of engineering with some fascinating development.

Cortex 1 was launched as part of C’Space, an event allowing students to launch experimental rockets. Stuffed with sensors and entirely 3D printed, Cortex 1 flew well, but the parachute failed to deploy mainly due to an imperfectly bonded assembly. The hatch was recovered, but the rocket was lost. Lessons were learned, and Cortex 2 was drafted up before the end of the event.

Some of the changes included tweaking the shape and reducing weight, and the refinements also led to reducing the number of fins from four to three. The fins for Cortex 2 are also reinforced with carbon fiber inserts and are bolted on to the main body.

Here’s an interesting details: apparently keeping the original fins would result in a rocket that was “overstable”. We didn’t really realize that was a thing. The results of overstabilizing are similar to a PID loop where gain is too high, and overcorrection results in oscillations instead of a nice stable trajectory.

Cortex 2 uses a different rocket motor from its predecessor, which led to another interesting design issue. The new motor is similar to hobby solid rocket motors where a small explosive charge at the top of the motor blows some time after the fuel is gone. This charge is meant to eject a parachute, but the Cortex 2 is not designed to use this method, and so the gasses must be vented. [Foaly] was understandably not enthusiastic about venting hot gasses through the mostly-PLA rocket body. Instead, a cylindrical cartridge was designed that both encases the motor and redirects any gasses from the explosive charge out the rear of the rocket. That cartridge was SLA printed out of what looks to us like Formlabs’ High Tempurature Resin.

Finally, to address the reasons Cortex 1 crashed, the hatch and parachute were redesigned for better reliability. A servo takes care of activating the system, and a couple of reverse-polarity magnets assist in ensuring the hatch blows clear. There’s even a small servo that takes care of retracting the launch guide.

The rocket is only half built so far, but looks absolutely fantastic and we can’t wait to see more. It’s clear [Foaly] has a lot of experience and knowledge. After all, [Foaly] did convert a Makerbot printer into a CNC circuitboard engraver.

DIY Falcon Heavy 2nd stage test flight of BPS.space

Rocket Science With The Other SpaceX

When you say that something’s not rocket science you mean that it’s not as hard to understand or do as it may seem. The implication is that rocket science is something which is hard and best left to the likes of SpaceX or NASA. But that’s not the hacker spirit.

Rocket science with BPS.Space[Joe Barnard] recently had an unsuccessful flight of his Falcon Heavy’s second stage and gives a very clear explanation of what went wrong using those two simple concepts along with the thrust, which in this case is just the force applied to the moment arm.

And no, you didn’t miss a big happening with SpaceX. His Falcon Heavy is a homebrew one using model rocket solid boosters. Mind you, it is a little more advanced than that as he’s implemented thrust vectoring by controlling the engine’s direction using servo motors.

And therein lies the problem. The second stage’s inertia is so small and the moment arm so short that even a small misalignment in the thrust vectoring results in a big effect on the moment arm causing the vehicle to deviate from the desired path. You can see this in the first video below. Another issue he discusses is the high drag, but we’ll leave that to the second video below which contains his explanation and some chart analysis.

So yeah, maybe rocket science is rocket science. But there’s no better way to get your feet wet then to get out there and get building.

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