It’s fair to say that there’s really no phase of spaceflight that could be considered easy. But the case could be made that the most difficult part of a spacecraft’s journey is right at the very beginning, within the first few minutes of flight. At this point the vehicle’s booster rocket will be fighting with all its might against its own immense propellant-laden mass, a battle that it’s been engineered to win by the smallest of margins. Assuming the balance was struck properly and the vehicle makes its way off of the launch pad, it will still need to contend with the thick sea-level atmosphere as it accelerates, a building dynamic pressure that culminates with a point known as “Max q” — the moment where the air density imposes the maximum structural load on the rocket before quickly dropping off as the vehicle continues to ascend and the atmosphere thins.
While the vast majority of rocket launches have to contend with the realities of flying through the lower atmosphere, there are some exceptions. By launching a rocket from an aircraft, it can avoid having to power itself up from sea level. This allows the rocket to be smaller and lighter, as it doesn’t require as much propellant nor do its engines need to be as powerful.
The downside of this approach however is that even a relatively small rocket needs a very large aircraft to carry it. For example, Virgin Orbit’s LauncherOne rocket must be carried to launch altitude by a Boeing 747-400 airliner in order to place a 500 kg (1,100 lb) payload into orbit.
But what if there was another way? What if you could get all the benefits of starting your rocket from a higher altitude, without the cost and logistical issues involved in carrying it with a massive airplane? It might sound impossible, but the answer is actually quite simple…all you have to do it throw it hard enough.
We aren’t sure if you really need lasers to build [HoPE’s] laser harp. It is little more than some photocells and has an Arduino generate tones based on the signals. Still, you need to excite the photocells somehow, and lasers are cheap enough these days.
Mechanically, the device is a pretty large wooden structure. There are six lasers aligned to six light sensors. Each sensor is read by an analog input pin on an Arduino armed with a music-generation shield. We’ve seen plenty of these in the past, but the simplicity of this one is engaging.
Since the first of our ancestors discovered that banging a stick on a hollow log makes a jolly sound, we hominids have been finding new and unusual ways to make music. We haven’t come close to tapping out the potential for novel instruments, but then again it’s not every day that we come across a unique instrument and a new sound, as is the case with this string-plucking robot harp.
Named “Greg’s Harp” after builder [Frank Piesik]’s friend [Gregor], this three-stringed instrument almost defies classification. It’s sort of like a harp, but different, and sort of like an electric guitar, but not quite. Each steel string has three different ways to be played: what [Frank] calls “KickUps”, which are solenoids that strike the strings; an “eBow” coil stimulator; and a small motor with plastic plectra that pluck the strings. Each creates a unique sound at the fundamental frequency of the string, while servo-controlled hoops around each string serve as a robotic fretboard to change the notes. Sound is picked up by piezo transducers, and everything is controlled by a pair of Nanos and a Teensy, which takes care of MIDI duties.
This plucky work in progress uses a strain gauge and an AD620 amplifier on every string to detect the tension when plucked. These amplifiers are connected to Arduinos, with an Arduino every nine strings. The Arduinos send MIDI events via USB to a Raspberry Pi, which is running the open synth platform Zynthian along with Pianoteq.
The harp is strung with guitar strings painted with silver, because he wanted capacitive touch support as well. But he scrapped that plan due to speed and reliability issues. Strain past the break to check out a brief demo video.
The harp is an ancient instrument, but in its current form, it seems so unwieldy that it’s a wonder that anyone ever learns to play it. It’s one thing to tote a rented trumpet or clarinet home from school to practice, but a concert harp is a real pain to transport safely. The image below is unrelated to the laser harp project, but proves that portable harping is begging for some good hacks.
Enter this laser harp, another semester project from [Bruce Land]’s microcontroller course at Cornell. By replacing strings with lasers aimed at phototransistors, [Glenna] and [Alex] were able to create a more manageable instrument that can be played in a similar manner. The “strings” are “plucked” with the fingers, which blocks the laser light and creates the notes.
But these aren’t just any old microcontroller-generated sounds. Rather than simply generating a tone or controlling a synthesizer, the PIC32 uses the Karplus-Strong algorithm to model the vibration of a plucked string. The result is very realistic, with all the harmonics you’d expect to hear from a plucked string. [Alex] does a decent job putting the harp through its paces in the video below, and the write-up is top notch too.
To exclude musical instruments in the overflowing library of possibility that 3D printing enables would be a disservice to makers and musicians everywhere. For the minds over at [Makefast Workshop], an experimental idea took shape: a single stringed harp.
The TuneFast Harp needed enough notes for a full octave, robust enough to handle the tension of the string, a single tuning mechanism and small enough to print. But how to produce multiple notes on a harp out of only one string? V-grooved bearings to the rescue! The string zig-zags around the bearings acting as endpoints that rotate as its tuned, while the rigid PLA printing filament resists deforming under tension.
After a bit of math and numerous iterations — ranging from complete reconfigurations of part placements to versions using sliding pick mechanisms using magnets! — a melodic result!
SparkFun has a new wing of hardware mischief. It’s SparkX, the brainchild of SparkFun’s founder [Nate Seidle]. Over the past few months, SparkX has released breakout boards for weird sensors, and built a safe cracking robot that got all the hacker cred at DEF CON. Now, SparkX is going off on an even weirder tangent: they have released The Prototype. That’s actually the name of the product. What is it? It’s a HARP, a hardware alternate reality game. It’s gaming, puzzlecraft, and crypto all wrapped up in a weird electronic board.
The product page for The Prototype is exactly as illuminating as you would expect for a piece of puzzle electronics. There is literally zero information on the product page, but from the one clear picture, we can see a few bits and bobs that might be relevant. The Prototype features a microSD card socket, an LED that might be a WS2812, a DIP-8 socket, a USB port, what could be a power switch, a PCB antenna, and a strange black cylinder. Mysteries abound. There is good news: the only thing you need to decrypt The Prototype is a computer and an open mind. We’re assuming that means a serial terminal.
The Prototype hasn’t been out for long, and very few people have one in hand. That said, the idea of a piece of hardware sold as a puzzle is something we haven’t seen outside of conference badges. The more relaxed distribution of The Prototype is rather appealing, and we’re looking forward to a few communities popping up around HARP games.