256 upvotes, 4 direct replies (showing 4)
View submission: Why are submarines and torpedoes blunt instead of being pointy?
Yep! And the reason subs and aircraft have blunt leading edges and tapered trailing edges is so that the laminar boundary-flow layer converges better at the rear. (As another commenter said, it's much easier to push air or water out of the way of the front than it is to draw it back into place at the rear.) If you get flow separation, there's a lot of turbulent fluid rolling off the rear of the vehicle. In aircraft this is almost solely a drag management issue, but for submarines that turbulent wake also risks cavitation, which renders the vessel much more vulnerable to hostile detection.
Comment by Serial138 at 01/02/2022 at 00:45 UTC
39 upvotes, 2 direct replies
So Subs give away their position with cavitation noise, what’s the downside for passenger planes? Turbulence?
Comment by UnamedStreamNumber9 at 01/02/2022 at 02:31 UTC
4 upvotes, 0 direct replies
It’s actually to delay as long as possible the position along the hull which the laminar flow does detach and become turbulent. There’s also the desire to have a symmetrical hydrophone array on the nose to listen from inside that laminar flow
Comment by [deleted] at 01/02/2022 at 04:06 UTC
0 upvotes, 1 direct replies
[removed]
Comment by The-dude-in-the-bush at 01/02/2022 at 04:52 UTC
1 upvotes, 1 direct replies
So the round shape is aerodynamic enough to decrease resistance but also needs to be there to let the water reform behind it. Also how does this change with ballistics such as tank shells, most are pointed (except for HE and HE squash heads) and like torpedoes, need to hit armour. Is it because of velocity or the medium th y travel in?