Make Physics Fun With A Trebuchet

What goes up must come down. And what goes way, way up can come down way, way too fast to survive the sudden stop. That’s why [Tom Stanton] built an altitude recording projectile into an oversized golf ball with parachute-controlled descent. Oh, and there’s a trebuchet too.

That’s a lot to unpack, but suffice it to say, all this stems from [Tom]’s obvious appreciation for physics. Where most of us would be satisfied with tossing a ball into the air and estimating the height to solve the classic kinematic equations from Physics 101, [Tom] decided that more extreme means were needed.

Having a compound trebuchet close at hand, a few simple mods were all it took to launch projectiles more or less straight up. The first payload was to be rocket-shaped, but that proved difficult to launch. So [Tom] 3D-printed an upsized golf ball and packed it with electronics to record the details of its brief ballistic flight. Aside from an altimeter, there’s a small servo controlled by an Arduino and an accelerometer. The servo retracts a pin holding the two halves of the ball together, allowing a parachute to deploy and return the package safely to Earth. The video below shows some pretty exciting launches, the best of which reached over 60 meters high.

The skies in the field behind [Tom]’s house are an exciting place. Between flying supercapacitors, reaction wheel drones, and low-altitude ISS flybys, there’s always something going on up there.

Continue reading “Make Physics Fun With A Trebuchet”

High-Altitude Ballooning Hack Chat

Join us on Wednesday at noon Pacific time for the high-altitude ballooning Hack Chat!

The Cope brothers are our hosts this week. Jeremy, a computer engineer, and Jason, a mechanical engineer, have recently caught the high-altitude ballooning (HAB) bug. In their initial flights they’ve racked up some successes and pushed the edge of space with interesting and varied missions. Their first flight just barely missed the 100,000 foot (30,000 meter) mark and carried a simple payload package of cameras and GPS instruments and allowed them to reach their goal of photographing the Earth’s curvature.

Flight 2 had a similar payload but managed to blow through the 100K foot altitude, capturing stunning video of the weather balloon breaking. Their most recent flight carried a more complex payload package, consisting of the usual camera and GPS but also a flight data recorder of their own devising, as well as a pair of particle detectors to measure the change in flux of subatomic particles with increasing altitude. That flight “only” reached 62,000 ft (19,000 meters) but managed to hitch a ride on the jet stream that nearly took the package out to sea.

The Cope brothers will be joining the Hack Chat to talk about the exciting field of DIY high-altitude ballooning and the challenges of getting a package halfway to space (depending on how that’s defined). Please join us as we discuss:

  • The basics of flight – balloons, rigging, payload protection, tracking, and recovery;
  • Getting started on the cheap;
  • Making a flight into a mission with interesting and innovative ideas for payload instrumentation;
  • Will hobbyist HABs ever break the Kármán Line? and
  • What’s in store for this year’s Global Space balloon Challenge?

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the High-Altitude Ballooning Hack Chat event page and we’ll put that in the queue for the Hack Chat discussion.

 

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 6, at noon, Pacific time. If time zones have got you down, we have a handy time zone converter.

join-hack-chatClick that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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.

Why No Plane Parachutes? And Other Questions.

This week I was approached with a question. Why don’t passenger aircraft have emergency parachutes? Whole plane emergency parachutes are available for light aircraft, and have been used to great effect in many light aircraft engine failures and accidents.

But the truth is that while parachutes may be effective for light aircraft, they don’t scale. There are a series of great answers on Quora which run the numbers of the size a parachute would need to be for a full size passenger jet. I recommend reading the full thread, but suffice it to say a ballpark estimate would require a million square feet (92903 square meters) of material. This clearly isn’t very feasible, and the added weight and complexity would no doubt bring its own risks.

Continue reading “Why No Plane Parachutes? And Other Questions.”

Quadcopter Beer Delivery System

One of the major design challenges when it comes to building an efficient quadcopter is weight. The idea here is that the more you can trim down the weight of the frame, motors, and circuitry, the longer the batteries will last. Or, in [dalbyman]’s case, the more beer it can carry.

[Dalbyman]’s housemate built the actual quadcopter, but then [dalbyman] got a little inebriated and decided that, while the quadcopter was exciting on its own, it would be even better with this modification. The actual device is a modified Pringles can with two servo motors on the bottom with arms that hold the beer. A parachute is attached to the beverage can and the assembly is loaded in. With a simple press of a button, the servos turn the arms and the beer falls out of the tube. Hopefully the parachute deploys and gently (and accurately) floats the beer to the thirsty person on the ground!

This project is a simple step that goes a long way towards a beer delivery system even Amazon could be proud of, and also shows off the capabilities of quadcopters in general. Perhaps the next step could be to automate the beer delivery system!

 

Nose Cone Parachute Deployment From A Soda Bottle, Rubber Band, And Servo

nose-cone-parachte

This piece of engineering is so simple and elegant, you’ll want to build a pretty serious water rocket just so you can try it out. It’s an automatic parachute deployment system that you build into the nose-cone of your rocket. The main portion of the build is made out of plastic soda bottles (2 liter size) to end up with a chamber to store the chute, as well as a friction joint that holds the thing together.

The video after the break shows a complete tutorial on how to build one of these. It starts by tracing out a sine-wave-like pattern on the wall of the bottle. The staggered tongues that are left after cutting along this line make up the friction joint. After gluing a cone (the blue thing) to the bottom of the bottle, it receives the parachute and is then slipped over another bottle that makes up the body of the rocket. The rubber band wraps around the outside of the chassis, holding those plastic tongues in place. The loose end of the rubber band is hooked around the horn of a servo motor, which can then be triggered remotely, or by using a sensor of your choosing. There is even a spring made out of a loop of plastic bottle — you can see it just on top of the chute in the image above.

Need a launching system that is as fancy as the parachute system? Here you go.

Continue reading “Nose Cone Parachute Deployment From A Soda Bottle, Rubber Band, And Servo”

Adding Payload To An RC Cessna

For just a few bucks you can add a payload to your flying toys. In this case it’s a Cessna RC plane which now has an added surprise. The first thing to be dropped was a parachute with a weight on it (for testing purposes). But there are hints of future projects that will use the same system for different purposes.

As you can see in the image above, the system depends on an additional compartment attached to the bottom of the plane. It was built from foam board to keep the weight down and connects using rare earth magnets. The bottom of the enclosure acts as the door, hinging on a servo motor with a bamboo skewer as the axle. So far the test drops have gone pretty well, but some more work needs to be done with the parachute design. It only opens about 60% of the time. We can sympathize, having had to work out some of our own parachute issues.

Don’t miss video from the plane as well as the ground after the break.

Continue reading “Adding Payload To An RC Cessna”