Will modifications to unlogged tables also be flused to disk?

Hi,

I would like to use postgresql's unlogged tables on an embedded system
to avoid frequent writes to flash memory.
While documentation clearly states that unlogged tables don't have to
go through the WAL, it doesn't mention what happens to the data when
it is written directly to the database.

Will unlogged tables also cause sync/fsync calls, or will they stay in
the page cache of the system as they will be lost anyway after a
recovery?

Thank you in advance, Clemens