While hydrofoils lift out of the water thanks to an underwater fin, hydroplanes zoom along by riding directly on the surface of the water. A slick carbon-fiber scale model from startup CovaConcepts shows off the latter concept in a fun new video.
Both hydrofoils and hydroplanes are designed to make water travel faster, more efficient, and in many cases, more thrilling, but they do this in different ways.
Hydrofoils have one or more blades, known as foils, that sit beneath the water's surface. As an underwater propeller produces thrust, the foil provides lift and the boat or board above it rises up out of the water. This creates a condition where a passenger is effectively riding well above the water even though a part of the boat remains submerged. Because the boat is above the water's surface, and the engine and foil are below, hydrofoils provide extremely smooth rides, and are virtually immune to the water's chop. Drag is also reduced dramatically because most of the boat isn't touching the water at all.
Hydroplanes, on the other hand, also move by propellers in the water beneath their hulls. But when a hydroplane gets moving, the hull's design is what provides lift. As the speed increases, the wing-like shape of the boat causes it to rise slightly out of the water and basically skim across the surface on a cushion of air. Because hydroplanes have much more contact with the water's surface than hydrofoils, though, the ride can get a bit bumpy as you can see in this video of an H1 Hydroplane Racing competition in Madison, Indiana.
While both types of boats can crank up some serious speed thanks to their reduction in drag, it's likely due to the smoother ride offered by a hydrofoil that they've more easily entered the consumer market. The HydroBlade and the Sea-Doo Rise are two of the more enticing stand-atop personal foils we've covered, while the SpiritBARTech35EF is a gorgeous foiling passenger boat.
Now, a young inventor with a background in aerospace engineering, F1 wind tunnel testing, and aerodynamics has developed a scale model remote-controlled boat she calls the HydraJet, which you can see in action in the following video from her company, CovaConcepts.
As she explains, the electric boat is made from recycled carbon fiber and is powered by a 2,900-mAh battery. But what really makes it different from other hydroplanes out there is that the motor, a 70-mm electric ducted fan, sits on top of the boat, not under the water so in a way, the HydraJet is also an airboat in addition to being a hydroplane.
While this might seem like a concept that emerged from careful design, the inventor, who goes simply by her first name, Tamara, says that in fact, it was a way to save money in developing the HydraJet while she was a "stereotypically broke student." Developing an underwater motor would have required waterproofing multiple components which would have added cost. Keeping the motor out of the water was a simpler, and smart way to proceed on a budget.
Tamara says that in the future, she may experiment with new wing designs to see just how fast she can make the HydraJet travel so for now, it looks like the boat's design will be limited to its scale model. We're certainly hoping that one day she can scale it up and offer it to the masses. If that happens though, oddly, the design she says she'll pursue will be a foiling model so that it can deliver a smoother ride than the current iteration promises. Still, we think the HyrdaJet and its accompanying video offer a great look at the technology behind hydroplanes.
Source: YouTube
