radio control

R/C Whirlygig Is Terrifyingly Unstable

February 6, 2019 by 10 Comments

In the days during and immediately after World War II, aerospace research was a forefront consideration for national security. All manner of wild designs were explored as nation states attempted to gain the upper hand in the struggle for survival. The Hiller Hornet was one such craft built during this time – a helicopter which drove the rotor through tip-mounted ramjets. Unsurprisingly, this configuration had plenty of drawbacks which prevented it from ever reaching full production. The team at [FliteTest] had a soft spot for the craft, however, and used it to inspire their latest radio controlled experiment.

Initial experiments consisted of a modified foam wing from a model seaplane, with two left wings facing opposite directions, and joined in the middle. Two motors and props were fitted to the wings to provide rotational motion. After some initial vibration issues were solved, the improvised craft generated barely enough lift to get off the ground. Other problems were faced with centripetal forces tearing the propellers off the wing due to the high rotational speeds involved.

A second attempt started from scratch, with a four wing setup being used, with much higher camber, with the intention to generate more lift with a more aggressive airfoil, allowing rotational speeds to be decreased. The craft was capable of getting off the ground, but instabilities likened to the pendulum rocket fallacy prevented any major gain in altitude.

We’d love to see a redesign to solve some of the issues and allow the craft to sail higher into the air. If you think you know the solution to the whirly bird’s dynamic problems, be sure to let us know in the comments. It should be possible, as we’ve seen successful designs inspired by maple seeds before. Video after the break.

[Thanks to Baldpower for the tip!]

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Brushless R/C Rocket Tests Different Flight Regimes

January 25, 2019 by 29 Comments

Quadcopters are familiar, and remote control planes are old hat at this point. However, compact lightweight power systems and electronic flight controllers continue to make new flying vehicles possible. In that vein, [rctestflight] has been experimenting with a brushless electric rocket craft, with interesting results. (Youtube, embedded below.)

The build uses a single large brushless motor in the tail for primary thrust. Four movable vanes provide thrust vectoring capability. To supplement this control a quadcopter was gutted, and its motors rearranged in the nose of the craft to create a secondary set of thrusters which aid stabilization and maneuverability.

The aim is to experiment with a flight regime consisting of vertical takeoff followed by coasting horizontally before returning to a vertical orientation for landing. Preliminary results have been positive, though it was noted that the body of the aircraft is significantly reducing the available thrust from the motors.

It’s a creative design which recalls the SpaceX vertical landing rockets of recent times. We’re excited to see where this project leads, and as we’ve seen before – brushless power can make just about anything fly. Even chocolate. Video after the break.

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Arduino RC Transmitter For Homebrew Projects

January 15, 2019 by 3 Comments

The field of radio control has benefited much from the onward march of technology. Where a basic 2-channel setup would once have cost hundreds of dollars, it’s now possible to get a high-end 2.4GHz 9-channel rig for well under $100, shipped to your door. However, the vast majority of these systems are closed-source and built for purpose. Sometimes, there are benefits to doing things your own way, and that’s precisely what this project does.

At its heart, it’s a simple combination. An Arduino Pro Mini talks to a NRF24L01 which handles the wireless communication. At that point, it’s up to you – throw in as few or as many controls as you like. For this build, [HowToMechatronics] has gone with a twin-stick setup, with a pair of potentiometers and twin toggle switches to round out the options.

The build comes in handy, as it’s possible to program in whatever features you may need for a given project. [HowToMechatronics] has used it to control a hexapod robot, among other projects. It’s a build that shows that with cheap and readily available parts, it’s possible to whip up a custom solution to suit your needs.

If this topic interests you.it’s worth saying that even those closed source radio control products can sometimes be hacked.

[Thanks to Baldpower for the tip!]

Radio Control Buggy Gets V10 Power

January 12, 2019 by 12 Comments

Amongst the more difficult machining tasks in the world are those involved in the production of internal combustion engines. Thanks to the Internet, it’s now possible to watch detailed videos of master craftsmen assembling tiny desktop V8 and V12 engines in home workshops with barely a CNC in sight. However, up until now, most of these builds have been left on the test stand to bark and wail away. No longer – [Keith] has decided that needs to change.

We’ve seen [Keith]’s work before – particularly, his 125cc V10 build, featuring fuel injection, dual overhead cams, and even a supercharger. With several micro engines under his belt now, it was time to put them to work – the V10 is getting a new home in a 1/3rd scale RC buggy.

We’re not sure [Keith] has heard the phrase “off the shelf” – even the suspension dampers on this build are custom machined. Currently up to part 5, the chassis is coming together and there are plans for a hybrid powertrain, too. Carbon fiber and anodized parts are in abundance – this build is truly a work of art.

We can’t wait to see this V10 monster tearing up the dirt – It’s an ambitious build, but if anyone can pull it off, it’s [Keith]. Video after the break.

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RC Controller Becomes XInput Controller

January 5, 2019 by 4 Comments

XInput is an API that is used by applications to interface with the Xbox 360 Controller for Windows. The 360 controller became somewhat of a “standard” PC gamepad, and thus many games and applications support the XInput standard.

[James] is working on an entry for a robotics competition, and wanted a controller to use with their PC that was more suited to their build. They took an RC controller, and converted it to work with XInput instead.

The controller in question is the JJRC Q35-01, a trigger-type RC controller available for under $20. The conversion is executed neatly, with the original STM microcontroller being removed from the board, and the PCB traces instead being connected to a Teensy 3.5 which takes over running the show.

The conversion is remarkably complete, with the team not stopping at just reading the buttons and steering potentiometer. A USB logic analyzer was used to figure out how to control the LCD, and a calibration mode implemented just in case.

[James] has shared the work on Github so it’s reproducible for the average maker. We’ve seen plenty of builds in this space, like this tilt controller from [Electronoobs]. Video after the break.

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Fail of the Week: Hard Lessons in 3D-Printed Bushings for a Giant RC Car

December 25, 2018 by 18 Comments

Can you turn 47 pounds (21 kg) of PLA filament into a gigantic working 3D-printed RC car? No, no you can’t — at least not if you eschew proper bearings in favor of printed bushings.

That’s the hard lesson that [Joel Telling] learned with his scaled up version of the OpenRC F1 car, an RC car that can be mostly 3D-printed. The small version still has its share of non-printed parts, mainly screws and bearings. In his video series documenting the build of the upsized version, [Joel] elaborates on some of the reasons for going with printed bushings rather than bearings, which mainly boil down to hoping that the graphite lubricant powder he added would reduce friction enough to prevent the parts from welding themselves together.

The car came out looking great, and even managed to scoot about nicely for a few seconds before its predictably noisy and unhappy demise. But what was unexpected was the actual failure mode. The plastic-on-plastic running gear seemed to handle the rolling loads fine; it was the lateral force exerted on the axle by the tension of the drive belt that was too much for the printed bushing to bear.

As [Joel] rightly points out, it’s only a failure if you fail to learn something, so kudos to him for at least giving this a try. And all that PLA won’t go to waste, of course — everything else on the car worked fine, so adding one bearing should get it back on the road. He should check out our primer on bearings for a few tips on selecting the right one.

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Henry the Hoover Gets a Weapons Upgrade

December 1, 2018 by 12 Comments

In this day and age of unprecedented military expenditure, we’re used to seeing weapons upgrades across all manner of war fighting hardware – tanks, helicopters, attack aircraft, you name it. We’re somewhat less accustomed to seeing the same on a domestic appliance. Regardless, we now have Henry the Hoover packing some serious heat.

Originally a mere vacuum cleaner, Henry was given movement through two motors and gearboxes sourced from a children’s ride on vehicle. A tank was created out of copper pipe to store the flammable gas (which appears to be butane, as used in cigarette lighters), and discharge is controlled with a solenoid valve. Ignition is then handled by a pair of electric ignitors fired by relay. It’s all controlled over a standard hobby radio controller, so you can stand at a safe distance while flambeeing your rug.

It’s a dangerous project, but one that is particularly fun when Henry’s dazed and amused countenance is taken into account. But then again, you might like your flamethrowers wrist mounted, instead. Video after the break.

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