Steel is scarce. Wood is not an option. And you need a boat now. These wartime circumstances drove innovation in all kinds of crazy directions, and one somewhat less crazy direction — concrete boats. As [Peter Sripol] demonstrates in the video below the break, making an RC concrete boat isn’t hard. Making a fast one on the other hand is. But that didn’t stop him from trying, and we think the effort deserves a look.
Starting with a basic displacement style hull, [Peter] and his cohorts experimented with a simple RC boat that worked, but could only move at slow speeds. They turned things up a notch or two and instead modeled their concrete boat after an RC speedboat hull that they had on hand.
The construction methods left a lot to be desired though, and they even tried various wire meshes as rebar, but they proved too heavy. Eventually though, they got a working hull, and had some fun with it. Rather than try to make the hull watertight with a rudder and propeller, they opted for a ducted fan and an airboat style rudder to make what they call the “world’s fastest concrete boat”.
Whether it’s the fastest or not is unconfirmed, but it is fast and actually gets on step fairly nicely. We applaud the exploration of alternative materials and the experimentation with different build methods. If building things with concrete floats your boat, then be sure to check out this concrete pinhole camera.
What do you do when you have a whole warehouse sized facility and an industrial sized CNC foam cutter? Clearly, the only choice is to build giant RC aircraft, and that’s exactly what the folks at [FliteTest] teamed up with the illustrious [Peter Sripol] to accomplish. Did it work? Yes. Did it work well? We’ll let you be the judge after taking a gander at the video below the break.
[Peter Sripol], known for building manned ultralight electric aircraft from foam, was roped in as the designer of the aircraft. A very light EPS foam is used to cut out the flying surfaces, while a denser green foam board is sourced from the local home building store to construct the fuselage.
The build is anything but ordinary, and kids are involved in the construction, although the video doesn’t elaborate on it very much. You can see evidence of their excitement in the graffiti on the wings and fuselage- surely a huge success on that front! As for flying? Four large motors provide locomotion, and it’s barely enough to keep the beast flying. A mishap with the Center of Gravity demands a last minute design change which renders the rudder almost useless. But, it does fly, and it is a great step toward the next iteration. Just like every good hack!
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!
If there’s one thing you can count on [Peter Sripol] for, it’s for defining the the aviation category of “Don’t Try This At Home.” In the video below the break, [Peter] displays his latest terror of the skies: A powered paraglider backpack that has fifty electric motors. Does it fly? Yes. Was it a success? Eh… mostly.
As [Peter] even says in the video: Don’t try this at home. [Peter] has taken a paraglider, which is essentially a non-rigid fabric wing that to the untrained eye resembles a parachute, and powered it with fifty drone motors taken from other projects. Two motors each are mounted in a push/pull configuration inside a 5×5 array of 3d printed ducts.
While the experiment was essentially a success, it was also a failure due to not having enough power, too little battery life, and overall just not being that great. Does every experiment need to end in absolute success in order to have fun and learn lessons that can be applied to the next iteration? Definitely not! We applaud [Peter] for being willing to fail- although, we have to admit, failing is a lot easier when you’ve already got a parachute of sorts deployed!
Peter Sripol really likes building gravity defying death traps. He recently flew the fourth ultralight, which he designed and built himself. For a taste of what’s going on here, the wings have aluminum tube spars and are made of hot-wire-cut styrofoam sections.
To keep the plane simple, he got rid of ailerons entirely. For roll stabilization he angled up the wings noticeably, adding dihedral. This gives the aircraft passive stability, because as it rolls to a side, the upper wing’s lift decreases and the lower wing’s lift increases, forcing the plane to correct itself. Interestingly he kept the rudder controls on pedals instead of moving it to the stick, so the stick only controls the elevator.
It is powered by a single large brushless electric motor borrowed from the OpenPPG project. On the first test he used a two-bladed propeller, with a small pitch angle which required full throttle to keep flying. It can be compared to driving a car only in first gear. By moving to a three bladed propeller with a higher pitch angle, and increasing the length of the wings for more lift, [Peter] was able to cruise comfortably at about 30 MPH or 48 km/h.
Although this aircraft definitely performed better than [Peter]’s previous ultralight builds, piloting something like this isn’t for the faint of heart. Although he does extensive weight-loading and thrust testing before taking to the air, adding tail weight to piloted aircraft by simply taping a water bottle to the tail just felt wrong. But we aren’t aviation experts, so we won’t pass final judgement.
An electric wheelchair is at the heart of the build. After ripping out its internals, the two motors with gearboxes are directly connected to the two tracks, allowing differential steering. Holding everything together is a solid welded steel frame – essential for years of reliable sieging.
The tracks themselves are simple strips of wood, cut and assembled by hand onto a nylon belt. Meanwhile the track wheels and drive assembly are designed in CAD and cut with a CNC router from some plywood, a great choice for adding some precision to the most mechanically challenging part of the build. As always in [Peter]’s videos, a large portion is dedicated to testing – in this case with a rather large array of fireworks. We certainly wouldn’t want to be in his bad books considering his other souped-up weapons.
Mini indoor drones have become an incredibly popular gift in the last few years since they’re both cool and inexpensive. For a while they’re great fun to fly around, until the inevitable collision with a wall, piece of furniture, or family member. Often not the most structurally sound of products, a slightly damaged quad can easily be confined to a cupboard for the rest of its life. But [Peter Sripol] has an idea for re-using the electronics from a mangled quad by building his own RC controlled paper aeroplane.
[Peter] uses the two rear motors from a mini quadcopter to provide the thrust for the aeroplane. The key is to remove the motors from the frame and mount them at 90 degrees to their original orientation so that they’re now facing forwards. This allows the drone’s gyro to remain facing upwards in its usual orientation, and keep the plane pointing forwards.
The reason this works is down to how drones yaw: because half of the motors spin the opposite direction to the other half, yaw is induced by increasing the speed of all motors spinning in one direction, mismatching the aerodynamic torques and rotating the drone. In the case of the mini quadcopter, each of the two rear motors spin in different directions. Therefore, when the paper plane begins to yaw off-centre, the flight controller increases power to the appropriate motor.
Mounting the flight controller and motors to the paper plane can either be achieved using a 3D-printed mount [Peter] created, or small piece of foam. Shown here is the foam design that mounts the propellers at wing level but the 3D printed version has then under the fuselage and flies a bit better.