Autonomous Ground Effect Vehicle Demonstrator Aims To Speed Up Maritime Shipping

Ground effect vehicles, or ekranoplans, have the advantage of being more efficient than normal aircraft and faster than boats, but so far haven’t been developed beyond experimental prototypes. Fortunately, this doesn’t stop companies from trying, which has led to a collaboration between [ThinkFlight] and [rctestflight] to create a small-scale demonstrator for the Flying Ship Company.

The Flying Ship Company wants to use unmanned electric ekranoplans as high-speed marine cargo carriers that can use existing maritime infrastructure for loading and unloading. For the scale model, [rctestflight] was responsible for the electronics and software, while [ThinkFlight] built the airframe. As with his previous ekranoplan build, [ThinkFlight] designed it in XFLR5, cut the parts from foam using a CNC hot wire cutter (which we still want a better look at), and laminated it with Kevlar for strength. One of the challenges of ground effect vehicles is that the center of pressure will shift rearward as they leave a ground effect, causing them to pitch up. To maintain control when moving into and out of ground effect, these crafts often use a large horizontal stabilizer high up on the tail, out of ground effect.

A major feature of this demonstrator is automatic altitude control using a LIDAR sensor mounted on the bottom. This was developed by [rctestflight] using a simple foam board ekranoplan and [Think Flighs]’s previous airframe, with some custom code added to ArduPilot. It works very well on smooth, calm water, but waves introduce a lot of noise into the LIDAR data. It looks like they were able to overcome this challenge, and completed several successful test flights in calm and rough conditions.

The final product looks good, flies smoothly, and is easy to control since the pilot doesn’t need to worry about pitch or throttle control. It remains to be seen if The Flying Boat will overcome the challenges required to turn it into a successful commercial craft, and we will be following the project closely.

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Solar Powered Autonomous Tugboat For Rescuing Autonomous Vessels

[rctestflight] has built several autonomous boats, and with missions becoming longer and more challenging, he bought an inflatable kayak to serve as a dedicated rescue vessel. Instead of relying on outdated manual paddling, he built an autonomous solar-powered tugboat.

Towing test with kayak
♪ “Rum, treasure, ArduRover, Pixhawk 4 and so much solar, break of dawn till the day is over, the ship will surely go…” ♪

The tugboat uses a pair of molded fiberglass hulls in a catamaran configuration. The wide platform allows a pair of 100W solar panels to be mounted on top. It was [rctestflight]’s first time molding anything out of fiberglass, so there was quite a bit of trial and error going on. The mold was 3D printed in sections, aligned with dowel pins, and glued together. After the epoxy had cured, the mold halves could be split apart for easier removal of the hull.

As with most of [rctestflights] autonomous vehicles, control is handled by a Pixhawk 4 running ArduPilot/ArduRover. A pair of 76 mm brass propellers powered by brushless motors provide propulsion and differential steering. The motors get power from six LiFePO4 batteries, which charge from the solar panels via MPPT charge controllers. The hulls are covered with plywood decks with removable hatches and inspection windows. After a bit of tuning, he took the boat for a few test runs, the longest being 5.1 km with himself in tow in the kayak. At less than 5 km/h (3 mph) it’s no speedboat, but certainly looks like a relaxing ride. Many of [rctestflight]’s previous vessels were airboats to avoid getting underwater propellers tangled in weeds. It was less of an issue this time since he could just haul the tugboat close to the kayak and clear the propellers.

[rctestflights] are always entertaining and educational to watch, and this one certainly sets the standard for sea-shanty soundtracks at 13:32 in part two.

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Eliminate Vertical Stabiliser With ArduPlane

Flying wings are popular options for fixed-wing FPV flying, but they have one rather annoying characteristic: yaw wag. The flying wing will wobble on the yaw axis while flying, and this side-to-side movement is visible on the pilot’s FPV video feed. With a combination of split rudders and ArduPilot, [Think Flight] eliminated wing wag without using any vertical stabilizers.

Yaw wag usually occurs on flying wings that use a pair of small winglets instead of a large vertical stabilizer on the centerline. Split rudders, also known as differential spoilers, can be used for active yaw control by increasing drag on either wing independently. However, this requires very rapid corrections that are very difficult to do manually, so this is where ArduPilot comes in. [Think Flight] used its yaw dampening feature in combination with differential spoilers to completely eliminate vertical stabilizers and yaw wag. This is the same technique used on the B-2 stealth bomber to avoid radar reflecting vertical stabilizers. [Think Flight] also used these clamshells spoilers as elevons.

Using XFLR5 airfoil analysis software, [Think Flight] designed built a pair of flying wings to use these features. The first was successful in eliminating yaw wag, but exhibited some instability on the roll axis. After taking a closer look at the design with XFLR5, he found air it predicted that airflow would separate from the bottom surface of the wing at low angles of attack. After fixing this issue, he built a V2 to closely match the looks of the B2 bomber. Both aircraft were cut from EPP foam with an interesting-looking CNC hot wire cutter and laminated with Kevlar for strength. Continue reading “Eliminate Vertical Stabiliser With ArduPlane”

Ground Effect Drone Flies Autonomously

There are a number of famous (yet fictional) sea monsters in the lakes and oceans around the world, but in the Caspian Sea one turned out to be real. This is where the first vehicles specifically built to take advantage of the ground effect were built by the Soviet Union, and one of the first was known as the Caspian Sea Monster due to the mystery surrounding its discovery. While these unique airplane/boat hybrids were eventually abandoned after several were built for military use, the style of aircraft still has some niche uses and can even be used as a platform for autonomous drones.

This build from [Think Flight] started off as a simple foam model of just such a ground effect vehicle (or “ekranoplan”) in his driveway. With a few test flights the model was refined enough to attach a small propeller and battery. The location of the propeller changed from rear-mounted to front-mounted and then back to rear-mounted for the final version, with each configuration having different advantages and disadvantages. The final model includes an Arudino running an autopilot program called Ardupilot, and with an air speed sensor installed the drone is able to maintain flight in the ground effect and autonomously navigate pre-programmed waypoints around a lake at high speed.

For a Cold War technology that’s been largely abandoned by militaries in favor of other modes of transportation due to its limited use case and extremely narrow flight tolerances, ground effect vehicles are relatively popular as remote controlled vehicles. This RC ekranoplan used the same Ardupilot software but paired with a LIDAR system instead of GPS to navigate its way around its environment.

Thanks to [TTN] for the tip!

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RC Ekranoplan Uses LIDAR To Fly In Ground Effect

Ekranoplans are a curious class of vehicle; most well known for several Soviet craft designed to operate at sea, flying just above the waves in ground effect. [rctestflight] had accidentally come across the ground effect flight regime himself years ago, and decided it was time to build an ekranoplan of his own.

I want to see little ekranoplans in at least three top 10 pop film clips by summer’s end. Please and thank you.

While ground-effect flight can be quite stable for a heavy, human-scale craft, the smaller RC version suffered more from minor perturbations from the wind and such. Thus, a Pixracer autopilot was installed, and combined with a small LIDAR device to accurately measure altitude above the ground. With some custom tweaks to the Ardupilot firmware, the craft was able to cleanly fly along barely a foot off the ground.

The final effect is almost mesmerizing; it appears as if the craft is hovering via some heretofore unknown technology rather than just flying in the usual sense. It’s still sensitive to breezes and sudden drops in the terrain lead to a temporary escape from the ground effect region, but the effect is nonetheless impressive. It’s a nerve wracking video at times, though, with quite a few near misses with traffic and children. Regardless of the nature of your experimental craft, be cognisant of your surroundings. We’ve seen [rctestflight]’s Ardupilot experiments before, too. Video after the break.

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Drone Boat Sails Seattle

Thanks to the availability of cheap, powerful autopilot modules, building small autonomous vehicles is now well within the reach of the average maker. [rctestflight] has long been an enthusiast working in this space, and has been attempting long range autonomous missions on the lakes of Washington for some time now. His latest attempt proved to be a great success. (Video, embedded below.)

The build follows on from earlier attempts to do a 13 km mission with an airboat, itself chosen to avoid problems in early testing with seaweed becoming wrapped around propellers. For this attempt, [Daniel] chose to build a custom boat hull out of fiberglass, and combine both underwater propellers and a fan as well. The aim was to provide plenty of thrust, while also aiming for redundancy. As a bonus, the fan swivels with the boat’s rudder, helping provide greater turn authority.

After much tuning of the ArduPilot control system, the aptly-named SS Banana Slug was ready for its long range mission. Despite some early concerns about low battery voltages due to the cold, the boat completed its long 13 km haul across the lake for a total mission length of over three hours. Later efficiency calculations suggests that the boat’s onboard batteries could potentially handle missions over 100 km before running out.

It goes to show that, even with an off-the-shelf autopilot and mapping solution, there’s still a huge amount of engineering that goes into any successful long-range mission, whether land, sea or air.

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Six Degrees Of Freedom Omnicopter With Ardupilot

Modern multirotors are very maneuverable but are mostly limited to hovering in a single orientation. [Peter Hall] has gotten around this by building an omnicopter drone with six motors mounted in different orientations on a collapsed tetrahedron frame.

The shape of the frame consists of six tetrahedrons all joined together at a single point. With a motor in each frame, the drone can produce a thrust vector in any direction, to achieve six degrees of freedom. The control system is the challenging part of this project, but fortunately [Peter] is one of the Ardupilot developers. Unlike a standard multirotor, it doesn’t need to tilt to move around laterally but can keep its orientation constant. One of the limiting factors is that the motors need to stop and reverse rotation for direction changes, which takes time. At slow maneuvering speeds this isn’t a major problem, but at higher speeds rotation is noticeably less smooth.

Because the drone is symmetrical all around, keeping track of orientation is challenging for a human pilot, but it’s perfect for an autopilot system like Ardupilot. In the video after the break, [Peter] demonstrates this by flying the drone around while the autopilot rotates it randomly. The 6DoF control system is open source and a pull request is live to integrate it into the official version of Ardupilot. The obvious application for this sort of drone is for inspection in and around structures.

This omnicopter is an entry into the Lynchpin drone competition by the celebrity [Terrence Howard]. We’re not quite following his claims regarding the scientific significance of this shape, which he named the “Lynchpin”, but it works for drones. Continue reading “Six Degrees Of Freedom Omnicopter With Ardupilot”