Ah, the simple pleasures of a bike ride. The rush of the wind past your ears, the gentle click of the derailleurs as you change gears, the malignant whine of the dual electric jet turbines pushing you along. Wait, what?
Yes, it’s a jet bike, and its construction was strictly a case of “Why not?” for [Tech Ingredients]. They recently finished up a jet engine build using a hybrid design with electric ducted fans as compressors and fueled with propane. It was quite a success, and pretty spectacular, but left an embarrassment of riches upon its passing in terms of spare parts. The ducted fans, monstrous 90-mm 12s beasts, along with dual 150A ESCs found their way onto a mountain bike by way of a rear luggage rack. Pannier bags on each side hold the batteries, and a quick control panel went on the handlebar. The video below shows the build details and a couple of test rides, which show just how fast you can go with this setup. It may not be very practical compared to a more traditional hub motor, but it’s nowhere near as cool. Just be sure to wear your hearing protection.
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.
We’re not entirely sure what to call this one. It’s got the usual trappings of a drone, but with only a single rotor it clearly can’t be called by any of the standard multicopter names. Helicopter? Close, but not quite, since the rotor blades are fixed-pitch. We’ll just go with “monocopter” for now and sort out the details later for this ducted-fan, thrust-vectored UAV.
Whatever we choose to call it — builder [tesla500] dubbed it the simultaneously optimistic and fatalistic “Ikarus” — it’s really unique. The monocopter is built around a 90-mm electric ducted fan mounted vertically on a 3D-printed shroud. The shroud serves as a mounting point for the landing legs and for four servos that swivel vanes within the rotor wash. The vanes deflect the airstream and provide the thrust vectoring that gives this little machine its control.
Coming to the correct control method was not easy, though. Thanks mainly to the strong gyroscopic force exerted by the rotor, [tesla500] had a hard time getting the flight controller to cooperate. He built a gimballed test stand to work the problem through, and eventually rewrote LibrePilot to deal with the unique forces on the craft and tuned the PID loops accordingly. Check out the results in the video below.
Some attempts to reduce the number of rotors work better than others, of course, but this worked out great, and we’re looking forward to the promised improvements to come.
[Mark Rehorst] has been on the hunt for the perfect 3D printer cooling fan and his latest take is a really interesting design. He’s printed an impeller and housing, completing the fan using a hard drive motor to make it spin.
We should take a step back to see where this all began. Many 3D printers us a cooling fan right at the tip of the extruder because the faster you faster you cool the extruded filament, the fewer problems you’ll have with drooping and warping. Often this is done with a small brushless fan mounted right on the print head. But that adds mass to the moving head, contributing to problems like overshoot and oscillation, especially on larger format printers that have longer gantries. [Mark] just happens to have an enormous printer we covered back in January and that’s the machine this fan targets.
Make sure you give [Mark’s] Mother of all print cooling fansarticle a look. His plan is to move the fan off of the print head and route a flexible tube instead. He tried a couple of fans, settling on one he pulled from a CPAP machine (yes the thing you wear at night to combat sleep apnea) found in the parts bin at Milwaukee Makerspace. It works great, moving quite a bit more air than necessary. The problem is these CPAP parts aren’t necessarily easy to source.
You know what is easy to source? Old hard drives. [Mark] mentions you likely have one sitting around and if not, your friends do. We have to agree with him. Assuming you already have a 3D printer (why else do you want to print this fan?), the only rare part in this mix is the ESC to make the motor spin. Turns out we just saw a BLDC driver build that would do the trick. But in [Mark’s] case he found a rather affordable driver that suits his needs which is used in the video demo below.
A while back, we wrote about the ducted fan, single rotor, VTOL drone that [Armin Strobel] was working on. It wasn’t quite finished then, and hadn’t got off the ground yet. He’s posted an update, and from the looks of it, he’s made tons of progress, including a first flight with successful take-off and landing.
The successful flight was no coincidence. Tuning any kind of ‘copter is a tricky business. Handling them manually during testing could be outright dangerous. So he built two different test-beds from pieces of wood, some 3D printed parts and bearings. One lets him mount the drone and tune its pitch (and roll), while the other lets him tune the yaw parameters. And just like they do in wind tunnel testing, he fixed short pieces of yarn at various points on the air frame to check for turbulence. Doing this also gave him some insight into how he could improve the 3D printed air-frame in the next iteration. He repeated the tests on the two test beds, going back and forth to make sure the tuning parameters were not interfering with each other. He also modified the landing gear to improve stability during take-off and landing and to prevent tipping. [Armin] is using the PixHawk PX4 for flight control and a BeagleBone Black for higher level functions and control.
Once the first flight showed that the drone could do stable flight, he attached a Go-Pro and recorded some nice video on subsequent flights. The next steps are to fine tune the flight control parameters to ensure stable hovering with position hold and way point following. He may also 3D print an improved air-frame. For details about the build, check out our earlier blog post on the Ducted Fan Drone. Check out the two videos below – one showing the first flight of the Drone, and the other one about the test beds being used for tuning.
Multi-rotor fixed-pitch aircraft – quad, hexa, octa copters – are the current flavor of the season with hobby and amateur flight enthusiasts. The serious aero-modeling folks prefer their variable-pitch, single rotor heli’s. Defense and military folks, on the other hand, opt for a fixed wing UAV design that needs a launch mechanism to get airborne. A different approach to flight is the ducted fan, vertical take-off and landing UAV. [Armin Strobel] has been working on just such a design since 2001. However, it wasn’t until recent advances in rapid-prototyping such as 3D printing and availability of small, powerful and cheap flight controllers that allowed him to make some progress. His Ducted Fan VTOL UAV uses just such recent technologies.
Ducted fan designs can use either swivelling tilt rotors that allow the craft to transition from vertical flight to horizontal, or movable control surfaces to control thrust. The advantage is that a single propeller can be used if the model is not too big. This, in turn, allows the use of internal combustion engines which cannot be used in multi-rotor craft (well, they’ve proven difficult to use thus far).
[Armin] started this project in 2001 in a configuration where the centre of gravity is located beneath trust vectoring, giving the advantage of stability. Since there were no hobby autopilots available at the time, it was only equipped with one gyroscope and a mechanical mixer to control the vehicle around the vertical axis. Unfortunately, the craft was destroyed during the first flight, after having managed a short flight, and he stopped further work on it – until now. To start with, he built his own 3D printer – a delta design with a big build volume of 400mm3. 3D printing allowed him to build a structure which already included all the necessary mount points and supports needed to fix servos and other components. The in-fill feature allowed him to make his structure stiff and lightweight too.
Intending to build his own auto-pilot, he experimented with a BeagleBone Black connected to a micro controller to interface with the sensors and actuators. But he wasn’t too happy with initial results, and instead opted to use the PixHawk PX4 auto-pilot system. The UAV is powered by one 3-cell 3500mAh LiPo. The outside diameter of the duct is 30cm (12”), the height is 55cm (22”) and the take-off weight is about 1.2kg (2.6 pound). It has not yet been flown, since he is still waiting for the electronics to arrive, but some bench tests have been conducted with satisfactory results. In the meantime, he is looking to team up with people who share similar interests, so do get in touch with him if this is something up your alley.