Prompted by the reply received by Brian (see below).
OK, sailing directly into wind is possible for a vehicle on
wheels and for a boat. But as far as I know a balloon can
not be sailed in any way, and "? certainly ?" not directly
into wind. Even a cigar-shaped blimp can not be forced
to advance against the wind, unless a source of stored
energy is available. Right?
What is the essential difference between balloons and
boats? A boat is only partially immersed in the moving
medium (air) while a balloon is totally immersed in it.
Also the air resistance, for a given speed and shape, is
much smaller than water resistance (or slippage resistance
for wheels) . Those who say that a boat can not possibly
advance directly into the wind are thinking in terms of a
balloon model, as I did, initially.
Ludwik Kowalski
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brian whatcott quoted:
How close to the wind can a boat sail?
...
Oh, boy. Here we go again. Someone says he heard of a sailboat
with a wildmill propellor driving an underwater propellor pushing the
sailboat --without any other source or power -- directly into the wind.
Someone screams "Impossible!!" (I know my physics/sailing/whatever).
Someone else smugs back "Well, here's a picture of such a boat". #2
(and #'s 4/6/8/10/12/14) shout back "You're a dummy. That picture is
a fraud!! (I know my physics/sailing/whatever). #3 saying "Well
someone has a patent on such a boat". #5 says "I hold the patent".
#'s 2N shout "FRAUD!! You're ALL dummies!!" (I know my physics
/sailing/whatever). And so it goes for about four or five weeks.
Brian, save yourself some time. Either accept that such boats do
exist now, have existed for more than 20 or 30 years, that about
the time the first such boat arrived physicists argued whether it
was even possible and came to the conclusion that it is possible
(and indeed is just another variation on the lawn spinkler under
water "problem"), there is a UK patent on such a boat, and
Scientific Amercian has written up such a boat. Or ... you can
do a search on files for the last year or so, pull 'em and start
reading.