Despite what extraordinarily overpowered quadcopters suggest, the air pressure of whatever a flying machine flys at is extremely important. Pressure is dependent on altitude and temperature, and there are hundreds of NTSB investigations that have concluded density altitude – pressure altitude corrected for nonstandard temperature variations – was the reason for a crash. Normally density altitude is computed through a slide rule or a flight computer, with the pilot entering in altitude and temperature, but somehow accidents still happen. For his entry to The Hackaday Prize, [Neil McNeight] is building an automated density altitude calculator to automate the process entirely.
Instead of having a pilot enter the altitude and temperature into a flight computer manually, [Neil]’s device grabs the current altitude from a GPS unit, and reads the temperature with a tiny sensor acquired from SparkFun. With just a little bit of math, this device will spit out the altitude an airplane or ‘copter thinks it’s at.
While the FAA won’t allow instruments that are cobbled together on a breadboard, this does have a few applications in the RC world. There are extremely high performance racing quadcopters out there now, and knowing how the craft will perform before flying it will save a few props.
There are a few AVR microcontrollers with onboard temperature sensors. These temperature sensors are neither accurate nor precise, but they do work for a few use cases. [Thomas] came up with a little bit of code that runs on all AVR microcontrollers, and is at least as accurate as the sensors in the rare AVRs that have them.
Although not all AVRs have a temperature sensor, they do all have RC oscillators, and these RC oscillators are temperature sensitive. By combining the RC oscillator and watchdog timer, [Thomas]’ code can get a vague idea if it’s getting hotter or colder.
To prove his code works, [Thomas] took an ATtiny13A chip loaded up with a few bits of code and placed a heated coin on it. The chip was programmed to turn on an LED when it detected a rise in temperature, and predictably, the LED lit up. With a coin chilled in a bowl of ice water, another bit of code ran, flashing the LED.
While we’re sure it’s neither accurate nor precise, it does have its uses – overheating protection or a simple thermostat. You can check out a video of the code in action below.
Continue reading “Measuring Temperature On An AVR Without A Sensor”
[Bauwser] had some spare RC Helicopter parts laying around and cobbled together an RC Hovercraft. It worked but not to his liking. That’s okay though, he know it was just a prototype for what was to come; a fully scratch built hovercraft with parts spec’ed out specifically to make it handle the way [Bauwser] wanted.
He started out by sketching out some cool faceted shapes that would both look good and be easy to construct. Sheets of a light but rigid foam were then cut into the appropriate shapes and glued together to create a three-dimensional body. The foam was then covered with a layer of fiberglass and resin to add some strength. A hole was cut in the body to mount a 55mm ducted fan which provides the required air to fill the skirt and lift the vehicle. Another ducted fan is mounted at the back of the craft and points rearward. This ducted fan provides the forward thrust and a servo vectors this fan in order to make turns.
[Bauwser] sewed the skirt himself. It is made out of an old beach tent. The fabric is extremly light and flexible, perfect for a hovercraft. During the test runs, dirt and debris was getting trapped in the skirt tube. A quick trip back to the sewing machine to add some gauze netting fixed that problem and keeps debris collection to a minimum. In the end, [Bauwser] shows what a great DIY RC build can look like with a little planning and experimentation.
Need more DIY RC hovercrafts? Check this out…
Video after the break…
Continue reading “DIY RC Hovercraft Makes Batman Action Figure Envious”
It’s winter, and that means terrible weather and very few days where flying RC planes and helicopters is tolerable. [sjtrny] has been spending the season with RC flight simulators for some practice time. He had been using an old Xbox 360 controller, but that was really unsuitable for proper RC simulation – a much better solution would be to use his normal RC transmitter as a computer peripheral.
The usual way of using an RC transmitter with a computer is to buy a USB simulator adapter that emulates a USB game pad through a port on the transmitter. Buying one of these adapters would mean a week of waiting for shipping, so [sjtrny] did the logical thing and made his own.
Normally, a USB simulator adapter plugs in to a 3.5mm jack on the transmitter used for a ‘buddy box’, but [sjtrny] had an extra receiver sitting around. Since a receiver simply outputs signals to servos, this provides a vastly simpler interface for an Arduino to listen in on. After connecting the rudder, elevator, aileron, and throttle signals on the receiver to an Arduino, a simple bit of code and the UnoJoy library allows any Arduino and RC receiver to become a USB joystick.
[sjtrny] went through a second iteration of hardware for this project with a Teensy 3.1. This version has higher resolution on the joystick axes, and the layout of the code isn’t slightly terrible. It’s a great project for all the RC pilots out there that can’t get a break in the weather, and is also a great use for a spare receiver you might have sitting around.
The massive engineering-defying Helicarrier from the Avengers is a brilliant work of CGI. Too bad it’d never actually fly… Like… Never.
Luckily, that didn’t stop our favorite RC hackers over at FliteTest from making a scale model of it — that actually works! If you’re not familiar, the Helicarrier is a fictional ship, the pride of S.H.I.E.L.D’s air force, or is it their navy.
It’s a massive aircraft carrier with four huge repulsor engines built into it, borrowing tech from Stark Industries. The shear size of it is what makes it completely ridiculous, but at the same time, it’s also unbelievably awesome.
Unfortunately, repulsor technology doesn’t seem to exist yet, so the FliteTest crew had to settle with a set of 8 brushless outrunner motors, with two per “engine”. The whole thing is almost 6′ long.
It doesn’t handle that well (not surprising!) but they were able to launch another RC plane off of it, mid-flight! Landing however… well you’ll have to watch the video. Continue reading “Lego Avengers Assemble to the Helicarrier!”
For some people, R/C cars just aren’t enough. [djMedic2008] has gotten his hands on a monstrous 1/5 scale wheel loader. The loader weighs in at 500lbs, and can lift up to 250 lbs. It was built several years ago as a prototype by [Richard] at Tiny Titan Earth Movers.
The design is based upon huge machines made by companies like Caterpillar and Komatsu. The 4WD system is driven a DC motor through a worm gear reduction. Bucket operation and steering are both operated by a hydraulic system driven by an electric pump. Just like the full-scale machines, the mini loader uses an articulated steering system. The front wheels are locked in place while the entire chassis bends at the middle pivot point. This allows for a much stronger solid front axle.
After several years of hard life, the loader came to [djMedic] in need of some TLC. The biggest issue was that the rear axle bevel gear had lost several teeth. This gear is under enormous loads when the loader is turning. A gear made of harder steel was the easy answer. Thankfully, you can order high carbon steel bevel gears from Amazon. The repair video gives us a look at the design of the loader. The main components of the machine are welded up from steel sheet and tube stock. This means that [djMedic] won’t have a hard time finding spare parts for his machine once he puts it to work clearing snow, dirt, or anything else that gets in its way!
Click past the break to see the loader in action!
Continue reading “R/C Wheel Loader Clears Snow, Lifts People”
In the past, creating accurate replicas of models and fantasy objects was a task left to the most talented of cosplayers. These props need not be functional, though. [Steve Johnstone] takes replica model-building to the next step. He’s designing and building a model airplane that flies, and he’s documenting every step of the way.
Armed with a variety of 3D printing techniques and years of model-building experience, [Steve] is taking the lid off a number of previously undocumented techniques, many of which are especially relevant to the model-builder equipped with a 3D printer in the workshop.
As he continues his video log, [Steve] takes you through each detail, evaluating the quality of both his tools and techniques. How does a Makerbot, a Formlabs, and a Shapeways print stand up against being used in the target application? [Steve] evaluates a number of his turbine prints with a rigorous variable-controlled test setup.
How can we predict the plane’s center-of-gravity before committing to a physical design? [Steve] discusses related design decisions with an in-depth exploration of his CAD design, modeled down to the battery-pack wires. Though he’s not entirely finished, [Steve’s] work serves as a great chance to “dive into the mind of the engineer,” a rare opportunity when we usually discover a project after it’s been sealed from the outside.
3D printing functional parts with hobbyist-grade printers is still a rare sight, though we’ve seen a few pleasant and surprisingly practical components. With some tips from [Steve], we may complete this video journey with a few techniques that bump us out of the “novelty” realm and into a space where we too can start reliably printing functional parts. We’re looking forward to seeing the maiden voyage.
Continue reading “3D Printing RC Airplanes that Fly: An Engineer’s Chronicle”