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240 Articles

Amphibious Dragster Drives On Water

November 17, 2022 by No comments

Dragsters are typically about peak performance on a tarmac drag strip. [Engineering After Hours] took a different tack, though, building a radio-controlled amphibious dragster intended to cross small bodies of water.

The build is based on a Traxxas Raptor RC car. However, it’s been heavily reworked from a pickup-like design to become a dragster with a motor mounted in the rear. It’s also been fitted with a foam underbody to allow it to float when stationary. The rear tires have been replaced with 3D-printed versions with large paddles, which provide propulsion in the water.

Initial tests showed the car struggled to make progress in the water, as the paddle tires tended to drag the rear end deeper under water. The tiny dragster tires up front didn’t help it steer, in water either. Large foam discs were added to the front tires to enable them to act as better rudders.

Fitted with its water tires and foam floatation aids, the car can only drive slowly on land, but [Engineering After Hours] points out this is enough to call it amphibious. It does a better job at skittering around on water, and it was able to cross a local pond at low speed.

We’ve seen some other creative techniques for making amphibious vehicles, like these crazy star-shaped wheels. Video after the break.

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[Tom Stanton] Builds An Osprey

October 8, 2022 by 20 Comments

The V-22 Osprey is an aircraft like no other. The tiltrotor multirole military aircraft makes an impression wherever it goes; coincidentally, a flight of two of these beasts flew directly overhead yesterday and made a noise unlike anything we’ve ever heard before. It’s a complex aircraft that pushes the engineering envelope, so naturally [Tom Stanton] decided to build a flight-control accurate RC model of the Osprey for himself.

Sharp-eyed readers will no doubt note that [Tom] built an Osprey-like VTOL model recently to explore the basics of tiltrotor design. But his goal with this build is to go beyond the basics by replicating some of the control complexity of a full-scale Osprey, without breaking the bank. Instead of building or buying real swash plates to control the collective and cyclic pitch of the rotors, [Tom] used his “virtual swashplate” technique, which uses angled hinges and rapid changes in the angular momentum of the motors to achieve blade pitch control. The interesting part is that the same mechanism worked after adding a third blade to each rotor, to mimic the Osprey’s blades — we’d have thought this would throw the whole thing off balance. True, there were some resonance issues with the airframe, but [Tom] was able to overcome them and achieve something close to stable flight.

The video below is only the first part of his build series, but we suspect contains most of the interesting engineering bits. Still, we’re looking forward to seeing how the control mechanism evolves as the design process continues.

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24 Hours Of Le Airplanes

September 27, 2022 by 22 Comments

There’s no more famous road endurance race than the 24 Hours of Le Mans, where teams compete to see how far they can drive in a single 24-hour window. The race presents unique challenges not found in other types of racing. While RC airplanes may not have a similar race, [Daniel] a.k.a. [rctestflight] created a similar challenge for himself by attempting to fly an RC airplane non-stop for as long as he could, and a whole host of interesting situations cropped up before and during flight.

In order for an RC plane to fly for an entire day, it essentially needs to be solar powered. A large amount of strategy goes into a design of this sort. For one, the wing shape needs to be efficient in flight but not reduce the amount of area available for solar panels. For another, the start time of the flight needs to be balanced against the position of the sun in the sky. With these variables more or less fixed, [Daniel] began his flight.

It started off well enough, with the plane in an autonomous “return to home” mode which allowed it to continually circle overhead without direct human control. But after taking a break to fly it in FPV mode, [Daniel] noticed that the voltage on his battery was extremely high. It turned out that the solar charge controller wasn’t operating as expected and was shunting a large amount of solar energy directly into the battery. He landed and immediately removed the “spicy pillow” to avoid any sort of nonlinear event. With a new battery in the plane he began the flight again.

Even after all of that, [Daniel] still had some issues stemming from the aerodynamic nature of this plane specifically. There were some issues with wind, and with the flight controller not recognizing the correct “home” position, but all in all it seems like a fun day of flying a plane. If your idea of “fun” is sitting around and occasionally looking up for eight and a half hours. For more of [Daniel]’s long-term autonomous piloting, be sure to take a look at his solar tugboat as well.

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Scratch-Built RC Excavator Is A Model Making Tour De Force

September 16, 2022 by 20 Comments

Some projects just take your breath away with their level of attention to detail. This scratch-built RC-controlled model excavator is not only breathtaking in its detail, but also amazing for the materials and tools used to create it.

We’ve got to be honest, we’ve been keeping an eye on the progress [Vang Hà] has been making on this build for a few weeks now. The first video below is a full tour of the finished project, which is painstakingly faithful to the original, a Caterpiller 390F tracked excavator. As impressive as that is, though, you’ve got to check out the build process that starts with fabricating the tracks in the second video below. The raw material for most of the model is plain gray PVC pipe, which is sliced and diced into flat sheets, cut into tiny pieces using a jury-rigged table saw, and heat formed to create curved pieces. Check out the full playlist for a bounty of fabrication delights, like tiny hinges and working latches.

We can’t possibly heap enough praise onto [Vang Hà] for his craftsmanship, but that’s not all we love about this one. There are tons of helpful tips here, and plenty of food for thought for more practical builds. We’re thinking about that full set of working hydraulic cylinders that operates the boom, the dipper, and the bucket, as well as the servo-operated hydraulic control valves. All of it is made from scratch, of course, and mostly from PVC. Keep that in mind for a project where electric motors or linear actuators just won’t fill the bill.

If this construction technique seems familiar to you, it could because we featured a toolbox made out of similarly processed PVC pipes back in June.

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Small Combat Robots Pack A Punch In Antweight Division

August 22, 2022 by 6 Comments

Two robots enter, one robot leaves! Combat robotics are a fantastic showcase of design and skill, but the mechanical contenders don’t have to be big, heavy, and expensive. There is an Antweight division for combat robots in which most contenders weigh a mere 150 grams, and [Harry Makes Things] shows off four participants for Antweight World Series (AWS) 64.

Clockwise: ReLoader, Shakma, Sad Ken, and HobGoblet antweight combat robots.

Each of them have very different designs, and there are plenty of photos as well as insightful details about what was done and how well it worked. That’s exactly the kind of detail we love to read about, so huge thanks to [Harry] for sharing!

In combat robotics, contenders generally maneuver their remote-controlled machines to pin or immobilize their opponent. This can happen as a result of damaging them to the point that they stop functioning, but it can also happen by rending them helpless by working some kind of mechanical advantage. Continue reading “Small Combat Robots Pack A Punch In Antweight Division” →

Autogyro Models Are Hard — Even For [Peter Sripol]

May 9, 2022 by 12 Comments

Aviation consists of two major groups. Airplane enthusiasts, and helicopter enthusiasts. The two groups rarely get along, each extolling the virtues of their chosen craft. Somewhere in between are autogyro folks. People who like vehicles that blend the best (or worst) of both airplanes and helicopters. Aviation master [Peter Sripol] has dipped his toes into the autogyro world, but not without some trouble.

Autogyros are propelled by a propeller, like a plane. They also have a tail section that works similar to a fixed-wing aircraft. That’s where the similarities end though. Lift for autogyros comes in the form of a rotating set of blades, much like a helicopter. Autogyro rotors aren’t powered during flight. They utilize autorotation. The blades freewheel, spun by the air as the craft moves forward.

[Peter] recently got his hands on a full-scale autogyro. So it made sense to build a model to help learn to fly. This isn’t [Peter’s] first attempt with autogyro models. He’s built a few in the past, with limited success. This time he started from scratch and ran into even more problems!

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Tracked RC Vehicle Is (Mostly) 3D Printed

March 17, 2022 by 2 Comments

While wheels might seem like a foundational technology, they do have one major flaw: they typically need maintained roads in order to work. Anyone who has experience driving a Jeep or truck off-road likely knows this first-hand. For those with extreme off-road needs the track is often employed. [Let’s Print] is working on perfecting his RC tracked vehicle to take advantage of these perks using little more than 3D printed parts and aluminum stock.

This vehicle doesn’t just include the 3D printed tracks, but an entire 3D printed gearbox and drivetrain to drive them. Each track is driven by its own DC motor coupled to a planetary gearbox to give each plenty of torque to operate in snow or mud. The gearbox is mated to a differential which currently shares a shaft, which means that steering is currently not possible. The original plan was to have each motor drive the tracks independently but a small mistake in the build meant that the shaft needed to be tied together. [Let’s Print] has several options to eventually include steering, including an articulating body or redesigning the drivetrain to be able to separate the shaft.

While this vehicle currently has no wheels in order to improve traction, [Let’s Print] does point out that a pair of wheels could complement this vehicle when he finished the back half of it since wheels have a major advantage over tracks when it comes to steering. A vehicle with both could have the advantages of both, so we’re interested to see where this build eventually goes.

Thanks to [Joonas] for the tip!

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