there was a show on the attack on the discovery channel yesterday and I missed the part where they explained how the invention of wooden fins kept the torps from hitting bottom in the shallow harbor.
How did the fins work?
thx - Craig
With tailfins only, the torpedo dives quite a bit, depending on the angle of attack when it hits the water. I believe these supplemental fins were sort of canard-type surfaces that prevented the deep dive. Sort of turned it into a submarine with front and rear dive planes. The supplemental fins would be in front of torpedo CG, providing a nose up moment.
I could be wrong but it was my undertanding they designed the fins to break away from the torpedo on or shortly after contact with the water. The selection of wood made this frangible fin design possible. Now exactly how the fluid mechanics of a finless torpedo work is beyond me, but I think we can be sure they worked out the math so that any portion of these 600-700ft warships were well inside the 'flight envelope' of these unstable torpedos before they could go rogue.
WmB
I think the standard fins remained. These were supplemental fins to help keep the torpedos nose up as it flew through the air hit the water to keep it from diving too deeply. Torpedos dropped from about 50 feet tended to hit a bit on an incline and therefore dove into the water. In the ocean this was not a problem as the torpedo would quickly recover. The modified torpedos, in smooth water just hit at less of an angle. Upon impact they broke off and the now standard finnned torpedo ran hot and straight.
The problem could have also been fixed by redesigning the dropping mechanism but that would have been far too much work and might have required remodification for open ocean work and dropping the torpedo in a flatter manner might have given worse performance in ocean swells where the nose entering at a deeper angle might have had advantages.
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