lowlow: Все сообщения за 24 Мая 2009 года

au> з.ы.2 Ламинарный поток отрывается и станановится турбулентным сразу за максимальным диаметром, присоединяется(?) турбулентно уже на самом хвосте.

The aft part of the hull of the seaglider is longer than your design..

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au>> з.ы.1 Испытания показали что у этой формы сопротивление пропорционально скорости в степени 1.5. Вах...
S.I.> В каком диапазоне скоростей?

25 cm/s

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lowlow>> The aft part of the hull of the seaglider is longer than your design..
au> The aft part is about 38% in Seaglider. I made that crude sketch before I found a good drawing, just to ask people if this hull type is familiar to anyone. The Seaglider design is inherited from Advanced Expendable Mobile Target (AEMT), which in turn is based on some serious hydrodynamics research dating back to 1974. I'm just surprised that they found this unusual hull shape 30 odd years ago, and it was used only in some obscure target vehicle and than this glider.

2 m/s

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au> Nice photo there The hull is similar, but.. I am regularly amazed when I see some meticulously perfected hydrodynamic design later completely messed up by hatches and all kinds of added "warts". Those guys say that when they were testing the full-size model in an air tunnel, they put some sensor on it (just for testing). That sensor took 2% of front area, but added over 25% of drag, and I guess destroyed their laminar flow joy too until removed.

The behaviour in the air and in the water is not the same.
Molecules have not the same dimension, and the water is uncompressible.
But you know that already...

au> I have an impression that Seaglider is one of the best AUVs from the efficiency point of view. It's hull is based on some serious work, designed by one man who knew what he was doing, so their laminar flow over the forward section was kept intact. The fins and all is placed in the aft area where the flow is turbulent anyway. And the forward section does look like (slimy=laminar?) squid indeed.

The Seaglider has the advantage to have no engine.
With the pump-jet as you want, it will be necessary to define the better form of the aft part of the hull.

The complexe form is certainly much difficult to equip. For all the team, torpedo form is certainly the better form to equip the inside. And you don't need to a second hull (for exemple Los Angeles class SSN...)
Better performances or chip design ? With the crisis it's easy to found the answer...

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