I know of no actual measurement of drag with the FES (i.e. with prop
folded) but there was some report of comparison flying in a comp with
a similar glider of another make (Ventus?). Can’t recall the link now,
but it would have been either in Lak’s website or Luka’s (the designer/
developer).

For my money, any slight increase in drag is not only imperceptible
to me, but is (a tiny) part of a price I am willing to pay for its
advantages in my particular compromise – getting home without a
retrieve crew if a cross country does not pan out, and getting away
from virtually any launch if it is at all soarable, etc.

Chris N.