Why do helicopter pilots sit in the right seat and the copilot sits in
the left, while in airplanes it just the opposite, i.e. the pilot sits
on the left in an airplane and the co-pilot sits on the right?

Most ppl are right handed and therfor prefer the right hand for most
detailed flight control.

For flying helicopters you use both hands (and your feet):

With right hand you usualy control the cyclic control. This allows the
helicopter to move in any direction around a 360 degree circle,
including forward, backward, left and right.

With the left hand you control the collective control. Allowing the
helicopter to gain or lose altitude.

So... a right handed pilot would choose the right seat, because the
collective control is located between both seats. "Main control" is
right in front of the pilot.

How Helicopters Work
http://rbftp.org/aircrafthangar/works/helecopter/how_helecopters_work.htm

peachbush..

In researching your question, I have found everything from tradition
to effects on torque to not all helicopter pilots in all countries sit
on the right-hand side.  However, after reading all the discussions,
it appears to be leaning towards tradition.  I am posting this as a
comment as it is not a definitive answer to your question nor can I
cite any specific references.  If I come across something definitive,
I will let you know.  I can point to a newsgroup posting that provides
a theory:


http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=5ndo9f%24eun%40nuhou.aloha.net&rnum=8&prev=/groups%3Fq%3Dhelicopter%2Bpilots%2B%2522sit%2Bon%2Bthe%2Bright%2522%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3D5ndo9f%2524eun%2540nuhou.aloha.net%26rnum%3D8

Regards,

-THV

Another link on the subject:

http://www.aerospaceweb.org/question/helicopters/q0072.shtml