A DIY Functional F-35 Is No Simple Task

The advent of affordable gear for radio-controlled aircraft has made the hobby extremely accessible, but also made it possible to build some very complex flying machines on a budget, especially when combined with 3D printing. [Joel Vlashof] really likes VTOL fighter aircraft and is in the process of building a fully functional radio-controlled F-35B.

The F-35 series of aircraft is one of the most expensive defence project to date. The VTOL capable “B” variant is a complex machine, with total of 19 doors on the outside of the aircraft for weapons, landing gear and thrusters. The thruster on the tail can pivot 90° down for VTOL operations, using an interesting 3-bearing swivel mechanism.

[Joel] wants his model to be as close as possible to the real thing, and has integrated all these features into his build. Thrust is provided by two EDF motors, the pivoting nozzle is 3D printed and actuated by three set of small DC motors, and all 5 doors for VTOL are actuated by a single servo in the nose via a series of linkages. For tilt control, air from the main fan is channeled to the wing-tips and controlled by servo-actuated valves. A flight controller intended for use on a multi-rotor is used to help keep the plane stable while hovering. One iteration of this plane bit the dust during development, but [Joel] has done successful test flights for both hover and conventional horizontal flight.  The really tricky part will be transitioning between flight modes, and [Joel] hopes to achieve that in the near future.

The real Lockheed Martin F-35 Lightning II project is controversial because of repeated budget overruns and time delays, but the engineering challenges solved in the project are themselves fascinating. The logistics of keeping these complex machines in the air are daunting, and a while back we saw Marine ground crew 3D print components that they were having trouble procuring through normal channels.

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Hackaday Podcast 039: Elliot <3 Lightning Detectors, Ikea Dark Mode, The Smartest Watch, Solar Sailing The Sky, And VAWT Controversy

Hackaday Editors Elliot Williams and Mike Szczys recap a week full of hacks from the solar sailing RC plane that has zero power storage, to geeking out about lightning detectors and hacking Ikea LED controllers to unlock real dimming to building backyard wind turbines. We look up an IoT egg tray with appreciation not for the concept but certainly for the engineering, and scratch our heads on why one-hacker-smartwatch-to-rule-them-all seems like something that should happen but so far has only been a fleeting concept.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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Soaring With The Sun: 4 Years Of Solar RC Planes

Many of us have projects that end up spanning multiple years and multiple iterations, and gets revisited every time inspiration strikes and you’ve forgotten just how much work and frustration the previous round was. For [Daniel Riley] AKA [rctestflight] that project is a solar powered RC plane which to date spans 4 years, 4 versions and 13 videos. It is a treasure trove of information collected through hard experience, covering carbon fibre construction techniques, solar power management and the challenges of testing in the real world, among others.

Solar Plane V1 had a 9.5 ft / 2.9 m carbon fibre skeleton wing, covered with transparent film, with the fragile monocrystaline solar cells mounted inside the wing. V1 experienced multiple crashes which shattered all the solar cells, until [Daniel] discovered that the wing flexed under aileron input. It also did not have any form of solar charge control. V2 added a second wing spar to a slightly longer 9.83 ft / 3 m wing, which allowed for more solar cells.

Solar Plane V3 was upgraded to use a single hexagonal spar to save weight while still keeping stiff, and the solar cells were more durable and efficient. [Daniel] did a lot of testing to find an optimal solar charging set-up and found that using the solar array to charge the batteries directly in a well-balanced system actually works equally well or better than an MPPT charge controller.

V4 is a departure from the complicated carbon fibre design, and uses a simple foam board flying wing with a stepped KF airfoil instead. The craft is much smaller with only a 6 ft / 1.83 m wingspan. It performed exceptionally well, keeping the battery fully charged during the entire flight, which unfortunately ended in a crash after adjusting the autopilot. [Daniel] suspects the main reasons for the improved performance are higher quality solar panels and the fact that there is no longer film covering the cells.

We look forward to seeing where this project goes! Check out Solar Plane V4 after the break.

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Tacking Against The Sun: Flying A Batteryless Solar RC Plane Is Almost Like Sailing

Flying on the power of the sun is definitely not a new idea, but it usually involves a battery between the solar panels and the propulsion system. [ukanduit] decided to lose the battery completely and control the speed of the motor with the output of the solar panels. This leads to some interesting flying characteristics, almost akin to sailing.

When a load tries to draw more current than a solar panel can provide, its output falls dramatically, so [ukanduit] had to take this into account. Using a ATTiny85, he built a MPPT (Maximum Power Point Tracker) unit that connects between the RC receiver and the motor speed controller. It monitors the output of the panels and modulates the speed of the motor accordingly, while ensuring that there is always enough power to run the servos and receiver. The airframe (named the Solar Bear) is a small lightweight flying wing, with a balsa and carbon fibre frame covered with clear film, with the solar cells housed inside the wing. Since the thrust of the motor is directly proportional to how much sunlight hits the top of wings, it requires the pilot to “tack” against the sun and use momentum to quickly get through turns before orienting into the sun again.

If you want to build your own controller, the schematics and software is up on RC Groups. Check out the Solar Bear in action, flown here by [AJWoods].

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Mini Quadcopter Becomes Paper Airplane

Several of us got Cheerson CX-10 mini quadcopters last year. We even bought some more to hand out as Christmas gifts. If you haven’t seen them, they are diminutive little flyers about the size of an English muffin. Thee’s no denying they are fun to fly around the house, and they do annoy the dogs.

However, like all cute toys, you eventually get bored just buzzing the dogs and cats. [JustforFun Media TK] decided that his needed a facelift, so he converted it into a paper airplane. This isn’t the paper airplane you folded up in school, either. This is a slick-looking jet aircraft.

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Move Over Red Bull, Hot Wire Foam Cutter Now Gives You Wings

Not many people will argue with flying RC airplanes is super fun. One big bummer is when a crash damages a part beyond repair. Sure, the RC pilot could keep buying replacement parts but doing so will add up after a while. RC plane builder and general guy with a cool name, [HuckinChikn], decided to build a hot wire foam cutter so making replacement wings would be quick and cheap.

The actual hot wire part is nothing special, just some wire pulled taut across a frame and a 24 vdc power supply pumping out current and heating the wire so it melts any foam in its path. The unique part of the build is that one side of the hot wire frame is secured in place and only allowed to pivot about that point. The other side of the frame traces an airfoil-shaped pattern. This setup allows [HuckinChikn] to make tapered wings. The difference between a straight wing and a tapered wing is similar to that of a cylinder and cone.

hotwire foam wing cutter

Check out the video after the break for a quick demonstration how easy it is to make a wing when you have the right tool!

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An Extremely Tiny 5.8GHz FPV Transmitter

Flying RC aircraft with a first person view is the latest and greatest thing in the hobby. In a fact that I’m sure will be shocking to 90% of people, you don’t need to buy a Phantom quad fly FPV. The guys at Flite Test show how you can build a tiny 5.8GHz FPV transmitter for under $100.

The parts used for this build are pretty much jelly bean parts at this point, but [Peter] at Flite Test is going for extremely lightweight parts for this build. He found an NTSC board camera that only weighs 1g and added a wide-angle lens. The transmitter is a tiny 200mW module that only weighs about 2g.

Why are the Flite Test crew going for small and light FPV setups? They just launched a new line of planes that can be built from a single piece of foam board. If you have a small micro quad, you can easily add FPV to it with this rig.