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Craig Blitzer Wrote: Listmates,
I am making final adjustments to flaps on my
IV-P. Does anyone know if I am supposed to use the "smart-tool" and make
sure that the flaps are indicating specific angles in certain
positions?
Craig, We haven't flown yet and I need to so qualify my
answer, which is: Rig each flap so it fully retracts at both track
guides, and then rig the connecting linkage so both flaps fully retract at
the same time. This takes at least two people; preferably three, and you'll
want to perform the check by pulling on the flap operating rod, rather than
pushing the flaps into the retracted position--for obvious(?) reasons. Check for
minimum binding and freedom of movement with the actuating cylinder
disconnected. This is not as trivial as it sounds, and some amount of
friction/binding will be present because the flap operating mechanism is not
linear and the tracks themselves are not completely parallel. Years ago, a
number of builders went to great pains to "straighten all this out." If anyone
ever fully succeeded, I never heard from them, but the bottom line is that they
work just fine, even though they are not mechanically "clean." The next step is
the most important: Connect the flap actuating cylinder and adjust it so it's
fully (bottomed or extended--I can't recall which) when the flaps are fully
retracted. You'll want to do the final test of this adjustment with the
hydraulic system functioning if you're setting this up earlier. The idea is to
have the linkage exert a slight load to hold the flaps fully retracted when
the cylinder is fully extended/retracted. If the cylinder has not reached it's
full throw, it will hold the flap operating mechanism under a high load, and
eventually fail some component. Now extend the flaps with the operating cylinder
attached so it moves to the other end of it's travel. Carefully remove the bolt
that connects the cylinder rod end to the center pivot and check to be sure
the flaps will extend just a bit farther. This is to confirm that the flap
mechanism is not hitting a stop or binding before the cylinder reaches it's full
travel. Same rationale as above. Last check is to retract the flaps, and set
your smart level on the flaps in a position that they can be extended without
moving the level (bottom?). Zero the indicator with the flaps in the retracted
position and then fully extend them using the hydraulic system if possible.
Check the angle on both sides. If they are within 2-3 degrees of each
other and within 5 degrees of the book value, consider your rigging a total
success. If it's not, see note below. If you see other problems, you're welcome
to call me...
NOTE: Lancair shipped hydraulic operating
cylinders in earlier kits with a longer throw/travel than normally needed.
Builders adjusted this by inserting a bushing inside the cylinder to
mechanically limit the travel, but cylinders in later kits were shortened to
provide the correct travel. If you have too much travel, you might check with
Vern at Lancair about the part number on your cylinder. If you have one of the
early ones, he probably still has some of the old bushings, or you can get a
shorter cylinder. Due to building variations, I'd carefully check the
replacement as outlined above anyway.
Bottom line is that, unlike the ailerons, elevator and
rudder, the flap extension angles are not critical. They should extend smoothly
without binding, retract fully, and not "rattle" when retracted. IMHO, these are
the primary considerations. Unless you've modified the Lancair-provided parts,
they will extend symmetrically by design, and should extend and turn down
approximately 40 degrees--with the exact amount not being critical at all.
Hope this helps,
Bob
Pastusek
703-271-8008
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