When we last left off, the Hackaday Drone Testbed was just a box of parts on workbench. Things have changed quite a bit since then! Let’s get straight to the build.
With the arms built and the speed controls soldered up, it was simply a matter of bolting the frame itself together. The HobbyKing frame is designed to fold, with nylon washers sliding on the fiberglass sheets. I don’t really need the folding feature, so I locked down the nylock nuts and they’ve stayed that way ever since. With the arms mounted, it was finally starting to look like a quadcopter.
Using the correct screws, the motors easily screwed into the frames. I did have to do a bit of filing on each motor plate to get the motor’s screw pattern to fit. The speed controls didn’t have a specific mount, so I attached them to the sides of the arms with double-sided tape and used some zip ties to ensure nothing moved. In hindsight I should have mounted them on the top of the arms, as I’m planning to put LED light strips on the outside of edges of the quad. The LEDs will help with orientation and ensure a few UFO sightings during night flights.
Power distribution is a major issue with multicopters. Somehow you have to get the main battery power out to four speed controls, a flight controller, a voltage regulator, and any accessories. There are PCBs for this, which have worked for me in the past. For the Hackaday Testbed, I decided to go with a wiring harness. The harness really turned out to be more trouble than it was worth. I had to strip down the wires at the solder joint to add connections for the voltage regulator. The entire harness was a bit longer than necessary. There is plenty of room for the excess wire between the main body plates of the quad, but all that copper is excess weight the ‘bench’ doesn’t need to be carrying. The setup does work though. If I need to shed a bit of weight, I’ll switch over to a PCB.
Click past the break to read the rest of the story.
Chances are, you take color for granted. Whether or not you give it much thought, color is key to distinguishing your surroundings. It helps you identify fire, brown recluse spiders, and the right resistor for the job.
Each color that makes up the spectrum of visible rays has a particular wavelength. The five principal colors—red, yellow, green, blue, and violet—make possible thousands of shades and hues, but are only a small slice of the electromagnetic spectrum.
We’ve probably all experimented with a very clear demonstration of the basic principles of lift: if you’re riding in a car and you put your flattened hand out the window at different angles, your hand will rise and fall like an airplane’s wing, or airfoil. This week’s Retrotechtacular explains exactly how flight is possible through the principles of lift and drag. It’s an Army training documentary from 1941 titled “
Airfoil models are also unit tested in wind tunnels. They are built with small tubes running along many points of the foil that sit just under the surface. The tubes leave the model at a single point and are connected to a bank of manometer tubes. These tubes compare the pressures acting on the airfoil model to the reference point of atmospheric pressure. The different liquid levels in the manometer tubes give clear proof of the pressure values along the airfoil. These levels are photographed and mapped to a pressure curve. Now, a diagram can be made to show the positive and negative pressures relative to the angle of attack.
