Today I installed a second adjustable flow valve into the flap return, or
"up", line.  That is, between the flap cylinder and the gear box bulkhead
fitting.  I am now able to set the extension speed and the retraction speed
to almost any desired rate.  I have initially set extension at six seconds
and retraction at twenty seconds.  I would like to hear from IV-P pilots who
are flying for input.
This was a very easy modification which can be removed quickly, too, by a
simple hose assembly change.  Access to the retract valve adjustment knob is
most easily made by removing the outflow valve bucket.
Walter Dodson  IV-P  97% and sneaking up on first flight
ps: I actually added fuel to the wing tanks today and determined undrainable
wing fuel quantity with drain valves in and removed.  One drop at a time...