Quote:
|
what's the deal with UUV "Gliders"? Its not like "lift" is a problem in water like it is in air. Why would a "glider" in water have increased range?
|
I am going to tackle this one first because I think it is pretty cool.
General categories of "flying"
-Alright, so you have powered flight (using engines, jets etc.) using thrust to move, and non-powered flight (gliders, jets with broke engines, squirrels etc.) using another force to move.
-You can also say you have heavier than air craft (planes, gliders), and lighter than air craft (baloons, zeplins etc.).
-You generally see wings on heavier than air craft, and wings work best once they are moving at speed, and do little when you are stopped.
Okay, so now to fly we need a way to get moving. A jet uses engines producing thrust to get the speed to have its wings work. A glider uses gravity (mostly) to get the speed to gets its wings going. Once the wing gets going, it uses the resistance (and 'suction') of air to direct it's path regardless of other forces, we call this "lift", though it doesn't really always have to do with gravity.
Okay, so how does this apply to underwater? Well water can be thought off as really-really thick air. So once again, you take a heavier than water craft, and put wings on it. Once again gravity is going to give the craft some force and speed, and the underwater wings, once they get going, are going to provide "lift". This allows an underwater glider to "glide" from a high point in the water, until it eventually lands on the sea floor. See how this can make something with wings travel farther?
Now another effect that is even cooler is this: Things can both, sink AND float in water. Fish do this with swim bladders, and submarines do this with balast tanks. By making themselves less dense than water (filling up with air) they float, and by making themselves more dense than water (usually pumping that air out, or letting water in) they sink! Make a UUV with balast tanks like a sub, and a battery allowing water in, and pushing the water back out again, and you have a vehicle that can sink, float, sink, float etc. Throw a wing on it, and it 'glides' along laterally to the bottom of the sea when sinking, then glides along laterally back up to the top when floating! This can go on forever or until the batter runs out, which ever is first.
Flying underwater with no engine producing thrust, and almost no moving parts: Efficient and quiet!
Super Cool huh? (yeah I am a geek).