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F.8L Falco Construction Manual
16–6
Revision 4, March 1, 2002
The forward fin spar has been changed to include a triangular block of spruce to allow for the
installation of the terminal block just mentioned. The opening at the bottom has been changed
slightly (the
30R
dimensions) to provide clearance for the rudder cable. To allow for drilling
through solid wood, the spruce block in the main fin spar has been extended down slightly. Also,
the top of the slot in the main fin spar has been raised slightly to provide clearance for the
elevator control arm.
The construction of the rudder has been changed slightly to simplify the installation of the upper
channel-nut for P/N 751. The previously-shown construction was difficult, requiring that the
doublers on the aft face of the spar be notched and boxed around the channel-nut. In these
drawings, the diagonal rib is installed above the channel-nut.
A jacking/tie down installation is now shown. A number of alternative installations were studied,
but all proved to be very difficult to install. This installation is similar to the installation for the
wing. Since the center of gravity of the Falco is forward of the wing jack points, the tail must be
held down during jacking, so an eyebolt is put in the fitting in the tail and used to keep the tail
down during the jacking process.
The COM antenna is now shown in the drawings installed in the fin, and the Loran antenna
coupler is shown installed on the forward fin spar.
All in all, we feel that the new tail group drawings are a big improvement and are about as good as
drawings can be. We hope you agree.
Hinge Installation Notes
When you install the hinges in the tail group, you may think that some of the bolts are too long.
In the Falco, we use MS21042 nuts. These nuts are shorter than the nylon stop nuts used on most
production aircraft. The nuts that we use are lighter, and—while the difference is small—the way
to keep weight down is to save on the ounces. Because the nuts are shorter, more threads are
exposed than with nylon stop nuts. This is a normal installation for this type of nut.
Some of the hinge bolts (those that go through the bronze bushings) are a little too long. The
bolts should have a washer installed under the bolt head and under the nut. Extra washers may be
used if needed.
The hinges are installed with channel-nuts. These are strips of steel formed over the heads of
bolts. They retain the bolts and allow the bolts to be permanently installed in the airplane. The
advantage of these things is that you do not have to have an access panel. The channel-nuts are
provided with a 1/8”Ø hole. This hole is provided for use on metal control surfaces, where a 1/8”
rivet is used. For the wood control surfaces you will be using a No. 6x1/2” sheet metal screw. This
screw is too large for the 1/8” hole, so you will need to ream the hole with a drill bit. It is not
essential that the hole be a tight fit over the screw. (One builder did not understand this and
went to the trouble to cut threads in the channel-nut. This is not necessary.)
By the way, the plans call out the screws as No. 6x1/2” TRA screws. For these sheet metal screws
there is no AN, NAS or MS part number. The proper description of the screws is “Truss, recessed
head, self-tapping sheet metal screw, type A”. The “truss” means that it has a rounded head. The
“recessed head” means that it uses a Phillips screwdriver. The “type A” means that the screw has
a sharp point. We abbreviate this as “TRA”. For flat head screws, we use the abbreviation of
“FRA”.
Summary of Contents for F.8L Falco
Page 1: ...F 8L Falco Construction Manual...
Page 7: ...l F 8L Falco Construction Manual Revision 4 March 1 2002...
Page 21: ...l F 8L Falco Construction Manual 1 8 Revision 4 March 1 2002...
Page 29: ...l F 8L Falco Construction Manual 2 8 Revision 4 March 1 2002...
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