The Fly Baby Story - Oshkosh 365

Fokker Triplane Planning
In this view of the miniature construction model, the
original Fokker Triplane structural configuration is evident.
Simplicity is the keynote in this structure.
IN PLANNING the necessary modifications to adapt
the original Fokker Triplane structure to take a modern
reliable engine and make other desirable changes,
I have found it wise to build models to help work out
proposed designs. The accompanying photos show a pair
of miniature fuselage frames made for this purpose. One
shows the essentially original Fokker structure while
the other shows its extensively modified counterpart.
In making these models soldered metal construction
proved better and somewhat faster than the conventional
cemented wooden method commonly used for flying
models. When using a scale of IVfe in. equals 1 ft. 0 in.,
which is very convenient for scaling purposes, it will be
found that regular copper-coated mild steel welding rods
of l /s in., 3/32 in. and 1/16 in. diameter correspond to
1 in., % in., and Vz in. tubing sizes. It was found that
steel rods are better suited to this project than comparable
bronze brazing rods, because the steel conducts the
heat of soldering much less rapidly, thus allowing additional
members to be added to a cluster without the
whole joint springing apart. Since the real purpose of the
model is to better visualize different trussing schemes
it becomes an advantage to be able to remove or add
members at will.
"FLY BABY" . . .
(Continued from page 14)
I haven't done any aerobatics in it, mainly because
I'm no good at them. Only Dave Gauthier has. They looked
good from the ground, and he seemed pleased after the
short time he'd tried it. I'll let a real "pro" have a try
at it and give a report later. As for spins, it's a hard
fight to get it into one, and then it comes out by itself.
Stall is clean, with no tendency to drop either wing. With
the wires, it's easy to rig the wings to a bit of wash-out
so that there is plenty of aileron control through the
stall. Load factor? Jim Wickham ran a stress analysis
as the subject of a Chapter 26 EAA meeting, and it came
up as 7.
So there it is. I'll admit that it's not an airplane to
By John Doyle, EAA 2931
P. O. Box 13, Andover, Mass.
Generally, rods should be snipped to approximate
length with heavy diagonal cutters and then filed to
exact dimensions. It's unnecessary to make rounded
notches at the ends of struts as the solder fills the joint
well, but scarves often have to be filed to shape where
clusters occur. Splices, such as shown in the photos immediately
behind the cockpit where the longeron tubes
telescope into each other, are best accomplished by scarfing
both members and soldering them together before
jig assembly. As in the building of the full-size article
a suitable jig is absolutely necessary to align the members
in proper position while soldering is done. The
Fokker Triplane example lent itself well to the standard
side-frame type of construction. With a simple line
drawing of the frame tacked to a soft pine board 1 in.
by No. 18 brads were driven along both sides of the
members to hold them in place. Other jigs were found
useful to hold the completed side-frames in relative position
while cross pieces were added.
John Doyle's redesigned Fokker Triplane fuselage points
out the heavy reinforcing of the entire structure, especially
in the forward bays to acccommodate a modern,
reliable engine.
A Weller WD-135 soldering gun gave good results,
using 50/50 wire solder and Nokorode Fluid Flux. Acid
type fluxes should be avoided because rusting will occur,
making resoldering operations difficult. Rosin type
fluxes are also apt to prove unsatisfactory for they generally
do not work well on steel.
please everybody, especially those who have had previous
experience with homebuilts and have built up their
own ideas as to just what they want. I think that those
to whom speed and zip aren't so important will find it
"The Mostest" airplane that they can produce for the least
investment of money and labor. Careful notes were kept
on both of these. The raw materials in the original ship
cost $375, and the "used hardware" consisting of a majored
engine, used metal prop, instruments, wheels,
brakes, fuel tank, etc., came to $675 for a total of $1,050.
These at average market prices in 1960. Good horsetraders
and scroungers can doubtless cut this down considerably.
Time to build "Fly Baby" the first time, averaging
out the labor skills involved, was 720 hours, which
works out to about two hours a day for a year. £
SPORT AVIATION 15