Ground-Effect Vehicle To Carry Passengers Around Hawaii

Although Hawaii used to have a ferry service to access the various islands in the archipelago, due to environmental and political issues, air travel is now the only way to island-hop. Various companies have tried to fill this transportation gap, but have all been stymied for one reason or another. The latest to attempt to solve this problem is a unique one, however. The Hawaii Seaglider Initiative is currently testing a ground-effect vehicle for inter-island passenger service that hopes to use the unique characteristics of this type of aircraft to reduce costs and limit environmental concerns.

The Seaglider, with backing from the Hawaii state government and various corporate interests like Hawaiian Airlines, is actually an amalgamation of three different types of vehicle. It’s capable of operating like a normal, hulled boat at low speeds but has a hydrofoil for operating at higher speeds. Beyond that, its wings give it enough lift to leave the water but stay in ground-effect flight, flying low to the water to reduce drag and improve lift when compared to an aircraft flying out of the ground effect. The efficiency gains from this type of flight are enough that the Seaglider can use electric motors and batteries to make the trips from island to island.

While the ferry is not yet in service, flight testing of the vehicle is scheduled for this year. Ground-effect vehicles of this type do have a large number of obstacles to overcome, whether they’re huge military vehicles like the Ekranoplanes of the Soviet Union or even small remote-controlled crafts, including difficulty with rough seas and having to operate in a harsh salt water environment.

A Paddle Wheel Ground Effect Vehicle

Who said paddle wheels were just for leisurely riverboat cruises? [rctestflight] is smashing that image with a high-speed twist on the concept, using paddle wheels to propel a ground effect vehicle across water. In the video after the break, witness this blend of old and new as he tests various designs.

Over the past few years he’s worked on a series of ground effect vehicles which exploits the increased lift and reduced drag when flying close to a surface. Unlike full-sized counterparts, smaller RC models struggle to stay in this sweet spot due to less pronounced self-stabilizing feedback loops. This means a small scale vehicle tends to touch the water rather often, and bleeding a lot of momentum in the process.

He wanted to convert these losses into gains by giving the vehicles a boost of speed whenever it touches the water. It’s a popular trick with RC cars which will hydroplane for long distances as long as they can maintain speed. All the designs still required air propellers for takeoff and to help maintain speed. The final design didn’t really need the paddle wheel when the air and water was calm, but it definitely helped when things got choppy. He is already experimenting with different paddle designs but also plans to test some other types of surface drives.

For covered a number off small scale ekranoplans, including a previous version by [rctestflight] that uses lidar for altitude control. He has also collaborated with [Think Flight] to build a autonomous small scale prototype for a maritime shipping startup.

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This Machine-Vision Ekranoplan Might Just Follow You Home

What is it that’s not quite either a plane or a boat, but has characteristics of both? There are probably a lot of things that fit that description, but the one that [Nick Rehm] is working on is known as an ekranoplan. Specifically, he’s looking to make the surface-skimming ground-effect vehicle operate autonomously.

If you think you’ve heard about ekranoplans around here before, you’d be right — we’ve covered a cool LIDAR-controlled model ekranoplan that [rctestflight] worked on about a year ago, and more recently, [ThinkFlight]’s attempts to make an autonomous ekranoplan that can follow behind a boat. The latter is where [Nick] enters the collaboration, and the featherweight foam ground-effect vehicle shown in the video below is his test platform.

After sorting out the basic airframe design and getting the LIDAR integrated, he turned his attention to the autonomous bit, which relies on a Raspberry Pi 4 running ROS and a camera with a wide-angle lens. The Pi uses machine vision algorithms to find an “AprilTag” fiducial marker in the scene, which gives the flight controller information about the relative orientation of the ekranoplan to the tag. [Nick] tested tag tracking using an electric longboard, and the model ekranoplan did an admirable job of not only managing the ground-effect, but also staying on target right behind him. And hats off to [Nick] for keeping all the balls in the air and not breaking his neck in the process.

We’re looking forward to seeing what [Nick] built here end up in [ThinkFlight]’s big ekranoplan build. Ground-effect vehicles like these are undeniably cool, and it seems like they’ve got the potential to solve some interesting transportation problems.

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Ground Effect Aerodynamics On An RC Car

Ground effect aerodynamics will return to Formula 1 in a big way in the 2022 season, hopefully washing away the bad taste left in fan’s mouths after the recent controversial season decider. [Engineering After Hours] has experimented with F1 aerodynamics on RC cars before, and decided that it was time to try and implement a proper ground-effect design himself.

The aim of ground effect aerodynamics is to create a constriction for airflow between the bottom of the car and the ground underneath. This constriction accelerates the flow beneath the car, and as per Bernoulli’s principle, causes a corresponding pressure drop, sucking the car down onto the track. Viscosity also plays a role; from the car’s perspective, the road beneath the vehicle is moving backwards at some speed, pulling on the fluid thanks to the boundary layer on the ground itself. This further helps increase the strength of the effect.

A vacuum-formed undertray complete with side skirts was installed on the RC car in order to generate ground effect downforce. A quick test with a leaf blower indicates the system works, and that the side skirts are a key component.

Lateral acceleration was significantly improved by around 20% in testing with the ground effects installed, though [Engineering After Hours] admits that without a wind tunnel, the results aren’t the most scientific. However, with the undertray being relatively lightweight, we suspect the aero elements are likely providing plenty of benefit without too much of a negative effect on acceleration or handling.

Check out some of the other aero experiments [Engineering After Hours] has undertaken, too. Video after the break. Continue reading “Ground Effect Aerodynamics On An RC Car”

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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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 Ground Effect Vehicle Skims Over The Water

In the 1960s the Soviet Union began experimenting with what they called ekranoplans, ground effect vehicles (GEVs) that were something of a hybrid between a ship and a large airplane. Their stubby wings didn’t provide enough lift for the vehicle to fly in the traditional sense, the craft essentially rode on a cushion of pressurized air produced by the aerodynamic interaction between the wings and the surface of the water. But after decades of testing, the ekranoplan never became much more than a curiosity for American intelligence agencies to ponder over.

Now [Peter Sripol] has built his own version of what the CIA dubbed the “Caspian Sea Monster”, and judging by the video of him “flying” it around a lake, the design seems to tick all the boxes. The advantage of a GEV is that it’s far faster than a ship and more fuel efficient than an aircraft of similar size. They also operate low enough to avoid enemy radar, which made them very appealing for military applications. Not that any of those characteristics apply to an RC vehicle, but at least it looks cool.

Ironically, it took some extra effort for [Peter] to keep his scratch built ekranoplan from getting airborne. Built out of foam covered with aluminum tape, the craft was light enough that even the tiny wings were enough to break it free from the ground effect if it got going fast enough. It didn’t help that the electric ducted fan motors used were probably a bit too powerful as well.

But by carefully adjusting the throttle and control surfaces, [Peter] was able to keep his craft firmly planted in the ground effect most of the time. Seeing the large RC craft floating just a few inches over the water is very impressive, and thanks to the application of some Soviet-style iconography on its burnished aluminum body, it looks like found-footage from a Cold War test program.

Hackaday readers will likely be familiar with [Peter] and his exploits. From building his own human-scale airplane out of foam board to convincing a cordless drill that it can fly, he’s creations have never been overly concerned with the status quo.

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