Fail Of The Week: Hard Lessons In 3D-Printed Bushings For A Giant RC Car

December 25, 2018 by Dan Maloney 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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Go Up A Creek Without A Paddle

December 4, 2018 by Bryan Cockfield 31 Comments

Kayaks are a some of the most versatile watercraft around. You can fish from them, go on backpacking trips, or just cruise around your local lake for a few hours. They’re inexpensive, lightweight, don’t require fuel, and typically don’t require a license or insurance to operate. They also make a great platform for a solar-powered boat like this one with only 150 watts of panels and a custom-built motor with parts from an RC airplane.

[William Frasier] built his solar-powered kayak using three solar panels, two mounted across the bow of the boat using pontoons to keep them from dipping into the water, and the other mounted aft. Separating the panels like this helps to prevent all three of them being shaded at once when passing under bridges. They’re all wired in parallel to a 12V custom-built motor which is an accomplishment in itself. It uses custom-turned parts from teak, a rot-resistant wood, is housed in an aluminum enclosure, and uses an RC airplane propeller for propulsion.

Without using the paddles and under full sun, the kayak can propel itself at about 4 knots (7 kmh) which is comparable to a kayak being propelled by a human with a paddle. With a battery, some of the shading problems could be eliminated, and adding an autopilot to it would make it almost 100% autonomous.

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Henry The Hoover Gets A Weapons Upgrade

December 1, 2018 by Lewin Day 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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9 Planes Combine To Make One Giant Flexible Flier

November 28, 2018 by Adam Fabio 18 Comments

[Ran D. St. Clair] has created a unique flying machine in the Flex 9. It’s not every day that you see a completely new and unusual aircraft, but the Flex 9 definitely fits the bill. [Ran] took 9 radio controlled planes, connected them together, and made one giant plane — and with an 18-foot wingspan, giant isn’t a misnomer.

The planes that make up the Flex 9 are simple aircraft – foamboard wings, a boom, and a basic tail. The individual planes only have elevator control – no rudder, no ailerons. Power comes from a standard LiPo battery, ESC and brushless outrunner motor. The control system is interesting – every plane has a KK board flight controller running OpenAeroVTOL firmware. The center plane has a radio receiver and communicates to the other KK boards over standard servo wires. Rudder (yaw) and aileron (bank) control are achieved through mixing handled by flight controllers.

Even the couplings between the planes were carefully designed. [Ran] used an EPP foam core as a rubbery dampener, with plywood to strengthen the joint. Each joint is mounted at a 20-degree angle. As the planes bank relative to each other, the angle forces the airframe to twist, which should help the whole system stay level.

Check out the videos below for an explanation and a flight test. The Flex 9 launch isn’t exactly stable – there’s some crazy sinusoidal wobbling going on. But the mechanical and electronic dampeners quickly spring into action smoothing the flight out.

If you’d like to know more about the KK board, you can read about right here.

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Foam Airboat Is Cheap RC Fun

November 15, 2018 by Lewin Day 7 Comments

Archer fans and residents of Louisiana will already be familiar with the concept of the airboat. Put a powerful engine running an aircraft prop on a flat-bottomed hull, and you’ve got an excellent way to traverse the marshes of the American South. While a fully-fledged airboat might run you the best part of $100,000, this no-frills radio-controlled version is great fun at a much lower price.

The hull is built on a sheet of foam, which is cheap, readily available, and suitably buoyant for the task. It’s then kitted out with a brushless motor to run the prop and a servo to control the rudder. Lace it up with a radio receiver and speed controller and you’re good to go.

The build could readily be completed in well under a couple of hours, and is a great one to tackle with kids due to its mechanical simplicity. There’s room for extra creativity too – you can always substitute a watermelon if you’re feeling peckish. Video after the break. Continue reading “Foam Airboat Is Cheap RC Fun” →

Centurion Bridge Layer, Now In RC

November 14, 2018 by Lewin Day 1 Comment

Radio controlled models are great fun. Most of us have had a few RC cars as children and maybe dabbled with the occasional helicopter or drone. It’s a rare breed of modeler, however, that gets to drive a radio-controlled bridge laying tank.

The lads prepare to fight the good fight.

The model is a replica of the British Centurion Bridgelayer – a modified tank designed to allow mechanized units to readily cross rivers and similar obstacles in European battlefields. While the genuine article relied on hydraulics, the RC version takes a different tack. [hawkeye3guns] built custom linear actuators out of motors, gears, and brass to deploy the bridge.

The build shows other smart techniques of the enterprising modeler. Rather than start from scratch, the Centurion is built on a modified KV tank hull. After the modifications were complete, the tank received a lick of paint in the requisite British Army green. The final result is rather impressive.

It goes to show what can be achieved with some off-the-shelf parts and ingenuity. We’ve seen other impressive RC tanks before – like this French build with a homebrew targeting computer.

Fail Of The Week: Leaf Blowers Can’t Fly

November 12, 2018 by Dan Maloney 31 Comments

Leaf blowers, the main instrument of the suburban Saturday symphony, are one of the most useful nuisances. It doesn’t take much work with a rake to convince even the most noise-averse homeowner to head to the Big Box Store to pick one up to speed lawn chores. Once you do buy one, and feel the thrust produced by these handheld banshees, you might wonder, If I let go of this thing, would it fly?

[Peter Sripol] had that very thought and set about building a couple of leaf blower powered planes to answer the question. It’s probably not a spoiler alert to report that the answer is no, but the video below is a fun watch anyway. The surprising thing is just how close both planes came to succeeding. The first plane was a stripped-down Ryobi two-stroke leaf blower suspended from a giant wing and tail section that very nearly got off the ground. Version 1.1 gained a retractable electric boost propeller – strictly for take-offs – and lost a lot of excess weight. That plane practically leaped into the air, but alas, servo problems prevented [Peter] from shutting down the electric and flying on Ryobi alone. Even a servo fix couldn’t save the next flight, which cratered right after takeoff. A version 2.0, this time using a brutally modified electric leaf blower, was slightly more airworthy but augured in several times before becoming unflyable.

What can we learn from all this? Not much other than it would take a lot of effort to make a leaf blower fly. We appreciate all of [Peter]’s hard work here, but we think he’s better off concentrating on his beautiful homebrew ultralight instead.

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