Many readers are already familiar with the so-called drug submarines used to smuggle drugs from South America into Florida and the region. can be targeted – and legal – application.
Drug submarines come in many forms, most of which are not really true submarines. Instead, they are user-built semi-submersibles that are mostly underwater, but with a small conning tower/snorkel that protrudes slightly above the surface.
This design makes them very difficult for authorities to spot while avoiding the expensive and complex requirements of a true submarine. No abilities are required.
Scientists at Washington State University, led by Professor Konstantin Matveev, recently set out to further evaluate the merits of such semi-submersibles. To that end, they created a remote control model semi-sub that is 45 cm long and 10 cm wide (17.7 x 3.9 inches). It was tested at Wawa Wai Bay on the Snake River in Washington state and reached a top speed of 1.5 meters (4.9 feet) per second.
Experiments have shown that, at high speeds, full-size semi-submersible craft are more energy efficient than conventional surface craft. This is mainly due to the fact that a semi-submarine has a small horizontal surface area, which is the horizontal cross-section of the vessel at the same height as the waterline.
“There are essentially two components of drag on a ship: one is due to friction (proportional to wetted area) and the other is wave drag (depending on several factors such as surface area and speed). depends),” explained Matveev. “When frictional drag dominates, the semi-sub has more drag at low speeds. […] Wave drag becomes dominant. The semi-sub has a small surface area, so the wave resistance is low. Therefore, they will be more efficient than surface ships at their high speeds. “
Matveev also pointed out that due to the small surface area of the water, a full-size semi-sub should be less affected by waves. As a result, ocean-going cargo ships must slow down in heavy seas to stabilize their cargo, while cargo-carrying semi-submarines can maintain higher speeds.
A paper on this research, which Matveev co-authored with Washington State University alumnus Pascal Spino, was recently published in a journal. unmanned systemYou can see the model semi-sub in action in the following video.
semi-submersible
Source: Washington State University
