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Nicholas P
wrote:
I recently saw a L-IV with the standard
wing tips permanently attached with access panels cut into the bottom of the the
wingtip. The installation looked really neat.
Is there any good
reason why the wing tips ought not to be permanently attached?
The big pro for permanently
attaching the winglet is that you can build about 5 more gallons of fuel
into each wing. The cons are many:
1) You'll need to run your fuel
sensor probes from the center of the wing or build them in permanently--and
then add an access panel for the wiring hookup. The original IV/IV-P's had
the sensor probes installed from the wing root outward, but they were more
prone to leaks around the threaded base and the sensor itself, and you had to
pull the wings to work on the
sensors.
2) The fuel
vent/pressurization NACA scoop in the top of the winglet is a bit more difficult
to install/plumb, and you'll need to construct a "dry bay" for the lights/strobe
wiring.
3) the VOR antennae
installed inside the tips need to be deleted, or you can seal them into the skin
and add yet another "dry bay" to wire them up--although you may be thinking
about leaving out the VOR antennae these
days?...
My opinion: If you need
every available gallon of fuel it might be worth the effort, but just for
cosmetics, I wouldn't bother. You'll get more fuel for less trouble by making
the aft inside bay(s) of the wings into fuel tanks. Lancair sells a kit for
this. It's best installed before closing the wings, but it can be added later.
Recommend you talk to Vern Pifer and/or Tim Ong about this before "just doing
it."
To get a nice finish
when you build/add your wingtips, drill the winglet attachment holes for #6 or
#8 screws and tap the reinforced carbon wing tips to hold these screws. Install
the wingtips and finish the wings/tips as a unit. Then carefully dig out the
smaller screws, drill, countersink and nutplate for #10 stainless screws and
you'll have a near-perfect wing to tip transition. One other tip (no pun
intended): be sure to install your flaps (fully retracted) and
ailerons when you're aligning the trailing edge of the winglets. Most flying
Lancairs didn't do this during the build and the flap/aileron/winglet trailing
edges do not align. There is not a good way to correct this
later...
Good
luck!
Bob
Pastusek
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