On Dec 18, 7:12 am, "William Sommerwerck"
wrote:

When I visited a friend in Texas some years back with my R/C submarine, we
managed to get it to dive (in a swimming pool) to a point well beyond the
maximum spec'd radio range, and it got stuck (even though the "descent
propeller" had shut off), because it didn't have enough bouyancy to rise
from that depth!

You need a Sub-Saver device. It is a relay that at a no-signal
condition will either blow a ballast tank or set the planes to full-up/
full speed depending on how it is installed.

Most R/C subs rely on internally generated heat to maintain positive
pressure inside the hull, but a clever builder (if space is available)
will install a shrader-valve and pressurize the hull a bit before
putting the sub in the water. I can get a reliable 6' of depth under
most conditions. By that, I mean have full controls and all
functions.

Remember the principle of the Cartesian Diver... that is where many
sub operators run into trouble with negative bouyancy. Remember,
sinking a submarine is well within design parameters, and almost
anyone can do it - the trick is "unsinking" it afterwards.

Peter Wieck
Wyncote, PA