50th Anniversary Edition edited by Ron Wanttaja

50th Anniversary Edition edited by Ron Wanttaja
WELCOME to the world-wide family of FLY BABY builders.
THIS IS THE 10th printing of the plans document, from which nearly 300 examples have been
completed and flown in the United States and several foreign countries to this date.
The first printing was in February, 1963, and succeeding editions have incorporated minor
corrections and clarifications to the plans as they have been pointed out by the readers.
Photographs of individual variations have been added, along with reprints of SPORT AVIATION
articles, to give potential builders the benefit of others’ experience with their FLY BABIES.
Further safety information was added by pages 8-32 and 8-33 to the Ninth Edition in 1982 and
has been revised for this edition.
In all of these years, there has been no evidence of structural short-comings in the design or a
need to publish “fixes” to correct unsafe conditions. The recommendation for the rear spar carrythrough reinforcement on Page 9-9 is just that - not a requirement. The original FLY BABY has
flown over 1400 hours since 1960 without it.
Accidents and their causes are discussed in the SPORT AVIATION reprint starting on Page 8-29,
but one more should be mentioned. A new owner bought a used and out-of-license FLY BABY and
had a wing come off in level flight. It turns out that the airplane had been tied outside for a couple
of winters in Florida. Trapped water in the fuselage rotted out some of the lower structure to the
point where the rear spar pins pulled out of the spar carry-through under load. The new owner
had not even inspected the long-unused airplane for condition before flying it. Further, nothing is
known of the adequacy of the original varnish applications or the bottom drains that are specified
in the plans for the specific purpose of avoiding water damage.
This unfortunate event is mentioned here only to emphasize the importance of vigilant
maintenance to any airplane, homebuilt or otherwise, and the need to keep it in good condition and legal.
Peter M. Bowers
Seattle, Washington
January 1, 1985
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Introduction to the 50th Anniversary Edition
Fifty years ago, a Seattle engineer/author designed and built a pretty good airplane.
It wasn’t fast.
It wasn’t fancy.
It couldn’t haul the entire family.
It couldn’t perform eight-point rolls on takeoff.
About the only thing it DOES do is leave a grin on the face of just about anyone who flies it.
Pete Bowers generously let EAA Chapter 26 form a flying club around the original Fly Baby back it
the mid-1980s. I remember my first flight in N500F like it was yesterday. I remember breaking
ground, and laughing from the sheer joy of flying that little beauty.
I flew N500F in the club for about seven years. When Pete decided to sell the airplane, I bought
half-interest in a 1947 Stinson.
The Stinson was a great airplane. But it wasn’t a Fly Baby.
After a year and a half of partnership, a very nice local Fly Baby came up for sale. After talking
with my Stinson partner, I sold him my half-interest and bought the Fly Baby. Other than that
dalliance with the Stinson and the occasional Biannual Flight Review in a rented airplane, I’ve
flown Fly Babies almost exclusively for the past 25 years.
Health willing, I hope to fly them for the next 25 years as well.
I take my Fly Baby to fly-ins a lot. One of the most common comments I hear is, “I used to own
one of these a long time ago. I wish I still had it!”
Whether you’re planning to build your own, taking over someone else’s project, using the plans as
reference for the flying airplane you purchased, or just curious…well, I’ll echo Pete’s foreword:
“Welcome to the world-wide family of the Fly Baby!”
Ron Wanttaja
Auburn, WA
July 2011
Ron@wanttaja.com
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CAUTION CAUTION CAUTION
All copy machines distort the product slightly. When Pete Bowers took care that the companies
printing the plans ensured that this distortion was kept to a minimum.
However, the copying industry has undergone some considerable amount of change. This level is
of control is hard to find in this day and age.
The basic message is that the “full size templates” printed in the numbered pages
(e.g., Page 4-2, Page 10-6) of the plans shouldn’t be used for production. Check the
dimensions with a ruler, and if necessary, redraw them, either on a computer or by
hand. The key dimensions are always supplied.
D
EDITOR’S NOTES FOR THE 50th ANNIVERSARY EDITION
When going through the original set of plans, there was a strong temptation to “update” things.
Pete mentions prices in some areas of course, and these prices are for the 1960s.
Who wouldn’t want to buy a rebuilt A65 for $500??
I mostly resisted making these sorts of updates. This book is Pete Bowers speaking; let’s let him
tell the story in his own words. Curiously, the spell checker on my word processor occasionally
objected to Pete’s spelling of certain words (“Taxy” is an example). Again, I left Pete’s spelling
intact as well.
Similarly, I also resisted the temptation to dump a lot of my own writings into this plans set. I
have a lot of advice and information on my web page (www.bowersflybaby.com), but, again, this is
Pete’s book.
I did not include the reprinted material from EAA SPORT AVIATION magazine. If you are an
EAA member, you can access this material for free online.
I don’t change Pete’s words, but I sometimes add my own comments to provide additional
information in key areas. These generally involve two cases: First, the FAA regulatory
environment has changed (for the better) since the Fly Baby was developed. The FAA no longer
required pre-cover inspections for homebuilts, for example.
Second, fifty years of flight experience has provided some insight into the aircraft design, and
some suggestions for improved safety. A good example is the reinforcement applied to the aft
spar pin holes at Station 5.
When I do add my own comments, they’re in brackets, italicized, and labeled “RJW NOTE”:
[RJW Note: Yes, this is what they look like.]
As a general comment, Pete makes occasional reference to CAM Manual 18 (or “CAM 18”). This
has been updated and expanded over the years, and is now called Advisory Circular AC-43-13B.
It’s available from various bookstores, and usually can be found online.
During conversion to electronic format, effort was paid to keep the page numbering the same.
This explains why some pages seem to be a bit short. However, in some areas, slight shifting of
some text to and from the next page may have occurred. This attempt to maintain the same
pagination aids getting help from experienced builders who own original plans sets…if they tell
you to look on Page 4-4 for your answer, it should be found there.
You’ll find that Pete’s original “full size templates” are not necessarily full size, and are marked,
“Not Scaled Correctly – Please Redraw.”
This is not just a “why doesn’t that lazy character redraw the templates for us” matter. It’s a
matter of reproduction accuracy when scans of the plans drawings were incorporated into an
electronic document.
Several years ago, Marco Pinto generated a Computer-aided Drawing (CAD) of the main rib
section based on the airfoil shape and the spacing between the spars. He has made these CAD
(Computer-aided drawing) versions of the rib templates available for free download. In addition,
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others in the Fly Baby world have made CAD drawings available for most other dimensioned
parts on the aircraft. These can be found at:
http://www.bowersflybaby.com/tech/templates.html
Instructions are also provided to help you get accurate templates output by your printer.
Frank Stutzman did a great job of scanning the manual and performing an Optical Character
Recognition to generate text files. These have been checked to a great extent…but some errors
may persist. If in doubt, drop me an email at ron@wanttaja.com.
This set of plans was based on Pete Bowers’ last iteration, the 11th printing. All changes have been
incorporated, hence the page notations of previous changes are no longer included. Later editions
of the 50th Anniversary set will have change notations as required.
Ron Wanttaja
F
G
H
Table of Contents
(RJW Note: When generating this 50-page sample of the plans, the Table of Contents got really
hosed up because so much of the document disappeared. The following is an image of the actual
TOC…the real thing in the plans looks normal).
I
J
K
THE AIRPLANE
INTRODUCTION
FLY BABY is a structurally simple and easy-to-fly airplane designed to the requirements of the
Experimental Aircraft Association for home construction and storage in a space 7' x 8' x 20',
which is equivalent to the standard home garage.
Great emphasis has been placed upon safe flight characteristics and good low speed performance
for takeoff and landing at some sacrifice of high speed. The structure has been designed for
standard airplane engines from 65 to 85 horsepower and the aerodynamic features are of sizes
and proportions suited to obtaining the best all-around performance in this power range.
Because of this, there is not enough advantage to be gained from using engines of significant
higher power to offset the cost and weight penalties. Increasing the power to increase the
aerobatic capability is not recommended. FLY BABY will do simple recreational aerobatics very
well but is not intended for rough air show or competition maneuvers.
Because of the increasing difficulty of obtaining the 65 to 85 hp engines that are no longer
manufactured, many would be builders have written in to ask if the 100 h.p. Continental 0-200
engine can be used safely. The answer is yes; the 0-200 can be used without any reinforcement of
the structure. In fact, engines up to the 108 h.p. Lycoming 0-235 can be used safely without
compromising the structure or imposing a weight penalty. Engines heavier than the O-235 are
not recommended.
Questions have been asked, too, about the suitability of the Volkswagen engine as a substitute
powerplant for FLY BABY. While no one has tried one yet, the designer does not feel that this
engine has the necessary displacement to make a good-flying airplane of FLY BABY and does not
recommend it.
Allowance has been made for the fact that many builders will want to make minor departures
from the basic design, and some acceptable variations are shown in the photo page. However, no
changes should be made in really basic structure or in the size, setting, or location of the flight
surfaces.
Low wing monoplane configuration was chosen for the basic Fly BABY design for several reasons
- structural simplicity, suitability for low-cost easy-to-rig wire bracing to fuselage and landing
gear, maximum visibility for the pilot, and ease of pilot entry to the cockpit.
For those desiring to convert the basic low wing FLY BABY to an entirely different machine,
supplementary drawings are available for biplane wings which can be fitted to the same fuselage,
tail, and landing rear as FLY BABY 1B. The basic monoplane is FLY BABY lA. The biplane wings
are not designed to fold.
As a biplane, FLY BABY is comparable to most other home-built biplanes with the exception that
it is slightly larger than average, as is the monoplane, resulting in lighter wing loading and
improved takeoff and landing characteristics. The use of sweepback on both wings is to permit
interchangeability of wings between biplane and monoplane arrangements without changing the
pilot's seat, which was originally determined by the wing location and balance requirements of the
low wing monoplane with straight wings. To keep the pilot behind the upper wing center section
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instead of under it, the upper wing had to be located considerably forward of the lower, with
sweepback used to bring the center of pressure aft to the proper location.
Because of the significant differences in wing bracing, the biplane FLY BABY can use a shockabsorbing landing gear, even a single-strut type if the builder cares to work out the structural
modifications. The rigid landing gear, however, has proved quite satisfactory for over 1300 hours
of flying on the prototype FLY BABY and some 136 examples built from the plans. Both versions
can be fitted with Edo D-1070 pontoons or equivalent home-built versions.
AEROBATICS
This is a subject of great concern among amateur airplane builders and pilots. For an in-depth
discussion of the problem, plus others involving the structural integrity of homebuilts, see the
article on pages 8-29 through 8-31 that has been reprinted from the Experimental Aircraft
Association's magazine SPORT AVIATION.
THE MATERIALS
The structure of the standard FIX BABY is all wood which was chosen in consideration of
relatively low cost, general availability, and the shop facilities, tooling, and skills possessed by the
person undertaking the construction of a full-scale airplane for the first time. Anyone who can get
a passing grade in a high school woodshop course should be able to successfully build a FLY
BABY.
Metal work, and especially welding, has been kept to an absolute minimum. There is so little of
the latter that the builder can cut his material to size and then take it to a professional shop to
have the work done quickly without compromising the "do-it-yourself" requirements of airplanes
to be licensed in the amateur-built category. It was intended to develop an alternate steel tube
fuselage for FLY BABY, but so little interest has been shown that the designer cannot justify the
time and cost of building a test specimen and making drawings.
At the time FLY BABY was built in 1960, the use of some components from production
commercial aircraft was permitted and still is. One FLY BABY now uses shortened wings from a
Luscombe SA. The most commonly used items are engine mounts, fuel tanks, and cowlings.
However, for certification as amateur-built, the airplane must be 51% built by the builder.
Because the wings are wire-braced to the axles, landing gears from production airplanes should
not be adapted to FLY BABY unless they are made rigid in the process. This applies to the
monoplane FLY BABY; tie biplane can use a shock-absorbing gear. Be sure when adapting other
gear that the wheels end up in exactly the same position as specified in the plans.
Bills of materials for the necessary sizes and quantities of raw materials are listed in each of the
appropriate chapters in this plans book. Such items as wing spars, longerons, and rib cap strips
can be ordered from a lumber mill or specialty house cut to the proper cross-section dimensions
but not to the finished length without compromising the "amateur-built" requirement. The
addresses of some suppliers are given in Chapter 9. Other sources can be found in the
advertisements in SPORT AVIATION and the commercial magazines that feature homebuilt
airplanes and recreational flying.
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THE PLANS
The method of presenting the plans for FLY BABY is quite different from the traditional "Roll of
Blueprints" approach. Instead of a maze of full-size and meticu1ously dimensioned drawings,
most items are presented in reduced scale with accompanying step-by-step pictorial and written
instructions or a single convenient loose-leaf document. The isometric drawings are not always to
true scale. In some cases, individual parts are drawn in over-size to emphasize a detail or an
assembly method or undersize to avoid overlap or to fit into the available space. In such cases,
the important dimensions are given.
In recognition of the fact that close tolerances are hard to work to, even without the usual homeworkshop handicap of inexperience, sub-standard working area, and bare-minimum tooling,
many structural items have been designed with the deliberate intention that their final
dimensions be established by the procedure known as "Fit on Assembly". This eliminates wasted
material and time-consuming rework when inaccuracies, which are not in themselves critical,
prevent two mating parts from fitting together properly Because of this concept, many of the
parts are not dimensioned in as much detail as would ordinarily be expected.
The drawings also anticipate certain problems in the procurement of hardware and equipment.
In many cases, sizes for sheet metal or tubular parts are a recommended minimum only. The
airplane is of such a size that the weight penalty resulting from a change of metal thickness from
1/16" to 3/32" or even 1/8" on these parts is negligible. Therefore, it is not necessary to spend a
lot of time and effort trying to locate material of the exact specified size when plenty or perfectly
acceptable substitute material may be right at hand.
The same reasoning also applies to such "used hardware" items as fuel tanks, brakes, and brake
master cylinders. Mechanical brakes are just as suitable as the hydraulic type used on the
prototype FLY BABY. Since there are so many possible combinations of brakes and actuators it
would be pointless to illustrate them all in the drawings. If the builder is too inexperienced in
aircraft practice to determine acceptable part and material substitutions within the general intent
of these drawings, he should, in the absence of experienced neighbors, consult a licensed airframe
mechanic at the nearest airport or a Federal Aviation Agency Safety and Maintenance Inspector
(under U.S. Gov't., Dept. of Transportation, in the telephone directory).
THE WORKING AREA AND CONDITIONS
Building an airplane is not a big job. It is a whole collection of little ones whose degree of
simplicity or difficulty, independent of the builder's skill, is influenced to a large degree by the
available work area and conditions. Airplanes similar to FLY BABY have been built in
surprisingly illogical places, so it can be done without formal shop facilities.
However, suitable space where the work can be left standing is desirable. Since FLY BABY breaks
down to components of convenient size, a standard one-car garage with a work bench across one
end is suitable for the entire job. Minimum area for building the wing is enough to lay the 4-1/2 x
13 foot panel flat at a convenient working level and still allow room to work around each side and
iii
the ends with space available for the standing tools. The fuselage is just over 14 feet long without
the engine mount or rudder installed, and is two feet wide. Without the landing gear, the fuselage
can be taken through a standard door located to permit a nearly straight approach to it.
Depending on the relationships of various doors, this means that FLY BABY can be built in many
rooms of a regular house and then be removed without knocking out a wall in the classic "boat-inthe-basement" tradition.
Since the Weldwood glue recommended for FLY BABY must be used at temperatures above 70
degrees Fahrenheit, and the application of dope to the fabric should also be done at this
temperature, heat control in the working area is essential. Suitable glues are available for lower
temperatures, but with no heat control the doping may have to be deferred until warm weather.
Doping should not be done in a confined area without adequate force ventilation anyhow, so
unless a suitable shop is available, the job should be done outdoors in good weather or taken to
another shop. Nothing will kill family approval of a home-built airplane project faster than a
house full of dope fumes.
THE TOOLS
As with the working area, FLY BABY can be built with a bare minimum of tools but the job is
greatly simplified by having a proper selection for the various jobs. Items marked with an asterisk
(*) in the following list are considered absolutely essential. If these are not on hand in the home
shop, material will have to be taken elsewhere for the necessary work. Aside from a suitable
power saw and drill press the most essential tool will be an electric hand drill and an extension
cord and light. This is because so much work will be done on and inside the airplane rather than
on the bench as the job progresses.
SAWS
Table or radial arm saw *
Coping saw or jigsaw
Bandsaw or bayonet saw with stand *
Hacksaw *
Small strongback saw or hand saw
DRILLS
Bench drill or drill press *
Electric hand drill *
Drill bits to max. dia. 3/8" (with 1/4" shank for hand drill) *
FILES
Suitable flat, rounded, and rat-tail files for wood and metal finishing *
Coarse wood rasp
Rotary file for electric drill
Rotary rasp for electric drill (also called "Scotch Plane")
iv
C-CLAMPS
Minimum 4 6-inch *
Minimum 2 dozen 3-inch *
VISE (steel) *
TACK HAMMER *
BENCH SANDING DISC
BENCH GRINDING WHEEL
BLOCK PLANES
SCREW DRIVERS *
TIN SNIPS *
DRAW KNIFE OR SPOKESHAVE
THREE FOOT CARPENTERS SQUARE *
6' STEEL MEASURING TAPE
SOLDERING IRON
PINKING SHEARS
WELDING RIG
SAW HORSES (2 minimum) *
GLUE BRUSHES *
PAPER CUPS (unwaxed2 for glue and varnish) *
COLD CHISEL OR WIRE CUTTERS *
1/8" NICOPRESS *
BOX OR OPEN END WRENCHES TO 3/4" *
WORK PRACTICES
Many work hours can be saved and the various jobs simplified by organizing the work in an
efficient manner. While circumstances will dictate different procedures for different people
because of equipment, availability of materials, etc., a few time-saving suggestions can be
followed by almost everyone:
CUT AS MANY PIECES OF A SIZE AS POSSIBLE AT ONE TIME. Much time is wasted in resetting the tools (power saw, drill, etc.) when pieces are cut singly or a few at a time on an "asneeded" basis. Consideration must be given, however to the stipulation in F.A.A. Manual 18
that wood surfaces for gluing should not be exposed for more than 24 hours prior to gluing.
MIX GLUE WITH SPECIFIC JOBS IN MIND. Much expensive glue is wasted by mixing too
much for a particular job. The "pot life" of Weldwood glue is only four hours, so it can't be
saved for tomorrow. If quite a few items are to be glued over a fairly long continuous period,
like an afternoon of installing wing rib corner blocks, plan on mixing several small batches
during that time. Small batches are easier to mix and there is no question of approaching the
pot life limit as the job goes on. Similarly, take precautions against running out of glue in the
middle of a big and fast job such as laminating wing tip bows. Mix several small batches rather
than one big one, or have a helper mixing new ones as you use the first.
The best applicator for Weldwood glue is a l/2" to 3/4" paint brush. If the brush is washed out
in hot water before the glue sets, the brush can last for months. Weldwood is cheaper in 5pound cans, but constant opening of the can to take out small quantities ages it rapidly. It is
best to buy it in small cans.
PLAN VARNISHING SO AS NOT TO BLOCK OTHER WORK. Try to save varnishing that will
hold up other work in a particular area for the end of the work period so that it can dry
overnight or between sessions. When wet varnish is on some parts while others are being
worked on, be sure that shavings and chips don't fall in the varnish. Remember that dust from
saws and grinders can float all over the shop and settle on a wet varnish job clear across the
room from the tool.
v
Don't open the varnish can. Poke two nail holes on opposite sides of the lid and seal them with
pieces of masking tape. Pull the tape and pour varnish into a paper cup for mixing with
turpentine for small jobs. The can gets messy if varnish is poured over the lip, and after several
openings for pouring small quantities, the varnish begins to thicken and scum over. Although
cheaper by the gallon, it is best to buy varnish in quart cans. Be careful NOT to use WAXED
cups for varnish, glue, or dope. "Hot cups" are fine, but not Styrofoam or plastic cups.
USE SYSTEMATIC WORK HABITS. Try to plan the work on individual jobs ahead for several
days so as to have all the necessary material on hand and organize the most efficient sequence
for doing things. Much time can be lost by wondering "what to do next?" and then figuring out
how to go about it. Try to work on related jobs in sequence so that wood parts for several can
be cut at one time, etc Try to set up specified times for working, with an ideal objective of
being able to get some little thing, even if its only removing the clamps from yesterday's work,
done every day.
AVOID OBSTACLES TO PROGRESS. One of the major roadblocks to completion of any home
workshop project is objection by authoritative members of the family if legitimate family
obligations and relationships are neglected for the project0 This is a political matter beyond
the scope of this technical document, but is nevertheless a major item for consideration.
Other than the family situation, there are three major human causes of wasted time in
construction projects:
(1)
The first is the eager friend who is anxious to be helpful but doesn't know anything about
building airplanes or even handling tools. By the time you show him how, check his work;
and generally do it over, you could have done it several times yourself in addition to the job
you were working on. The exact and highly desirable opposite of this type, and
unfortunately very rare, is the experienced person who can be handed a job and forgotten
for a while as he gets it done with no fuss.
(2)
The second time-killer, more often plural than singular, is the curious and friendly type
who drops around from time to time "to see how you are doing" and brings a friend along
who has to have the whole project explained in detail from the very beginning. No work
can be done at all during most of these visits, and the visitors are very seldom inclined or
even qualified to help. A sub-category of this type is the one with whom a little knowledge
is a dangerous thing, and who is always trying to improve your design to death by
suggesting all sorts of things from little refinements to major rearrangements that will be
made with YOUR time, money, and materials.
One unforeseen by-product of both categories of this second type is the added expense to
the overall job resulting from the amount of your groceries, coffee, beer: etc., that they
consume while sitting around keeping you from working.
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(3)
The third major thief of your working time is yourself. As the plane begins to go together it
is entirely too easy to gaze dreamily at it by the hour, admiring your own handiwork and
engaging in all sorts of flights of fancy while sitting in the cockpit of an unfinished fuselage
perched on a pair of sawhorses0 Even if you don' t feel particularly ambitious when you go
out to the shop; or time is short, try to make sane tangible progress. Don't goof off for one
whole work period by kidding yourself with the thought that you'll really bear down on it
"tomorrow" or even "next week'.
Overdoing the improvements can be a personal matter, too, although in some cases it
stems from improving skill as the job progresses There may be such a difference between
the first few ribs you built and the last that you want to scrap the early ones and do them
over. Your own standards and time/cost considerations will be your only guides here.
RECORDS AND PAPERWORK
Keep a record of all purchases of material for your FLY BABY, whether new or used. This will
keep you informed of actual costs, will enable you to answer the inevitable question that you will
hear hundreds of times: "How much did it cost ya, mister?", and will enable you to help friends
who are considering a homebuilt and yourself when planning another. Most important of all,
however, it will enable you to establish a true cash value for your machine when the tax assessor
comes around. If he is not experienced in evaluating; aircraft (some states tax airplanes as
personal property while others use an excise tax) he may arbitrarily assign an unfairly high value
An the absence of substantiating figures Also, sales slips can show that state sales taxes have
been paid on the raw materials, another concern of the tax people when the plane is finished.
Try, too, to keep at least a rough check on your working time. The next-most-asked question from
the spectators is: "How long did it take you to build it?" There is satisfaction in being able to snap
off a concise and authoritative answer, either in terms of man-hours or days, weeks, and months.
It is a very good idea to start the airplane logbook at the time you start construction Information
as to the source and grade of raw materials can form a valuable historical record, and a record can
be kept of essential pre-finish FAA inspections. Since a homebuilt is not pinned down to an
approved bill of materials that is a matter of record as in the case of type-certificated production
models, a record should be included of the type of covering material, type of dope whether nitrate
or butyrate, and even the type of hydraulic fluid used in the brakes. You may forget over
subsequent years, or a new owner not know at all if it isn't recorded, with a resulting complication
of maintenance problems.
Other paperwork directly concerned with registration and certification of your airplane is covered
in Chapter 8, ASSEMBLY, TEST, AND FLYING.
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CONSTRUCTION PROCEDURES
Those who are generally familiar with aircraft construction and repair procedures should have no
trouble at all in any phase of building FLY BABY Those unfamiliar with aircraft practice, or skilled
only in one specialized field, should consult their more experienced friends before proceeding. In
any case, it is strongly recommended that anyone building FLY BABY or any other homebuilt
airplane obtain a copy or Federal Aviation Agency Manual 18, MAINTENANCE, REPAIR AND
ALTERATION OF AIR FRAMES, PROPELLORS, AND APPLIANCES, available from the
Government Printing Office, Washington 25, D.C., or some aircraft supply stores for $1.50. This
book is "The Bible" on all phases of aircraft construction and repair procedure. *
It is impossible to detail fabrication procedures down to the fundamental level of how to hold the
hammer. The drawings and instruction pre-suppose a competent skill level. There are, however,
certain construction procedures associated with aircraft standards of quality that should be
mentioned.
WOOD
Wood aircraft construction differs considerably from traditional cabinet and furniture-making
procedure. There are no mortises, tennons, or dovetail joints in aircraft. All wood-to-wood joints
are by glue in shear or by bolting. Bolt heads or nuts bearing against bare wood opposite a metal
fitting should be backed up by large-diameter wood washers. Wood screws are never used for
joining; small nails are used to hold glue joints under pressure while drying and then become
entirely redundant. Wood surfaces are protected from damage during clamping by use of
clamping backup blocks to distribute the load.
With the exception of' the wing spars and the slotted rib cap strips, it is much cheaper for the
builder to buy his spruce lumber in planks and saw it to size himself than to have it finished at a
mill. The cap strips can be cut The cap strips can be cut from standard l/4" "Cap Strip Stock" on
any circular saw, but cutting the 1/8" x 1/8" slot calls for exactly the right size. blade. A "planer"
blade should be used for finished rip cuts on all non-plywood wooden parts in FLY BABY.
Suppliers of aircraft grade wood that advertise in SPORT AVIATION, magazine of the
Experimental Aircraft Association (EAA) have been advised of the size and quantity of the FLY
BABY materials, and will be able to make "package" deals at fixed prices.
METAL
while there is very little metal in FLY BABY, certain practices must be observed. Most of the
S.A.E. 4130 sheet steel fittings can be bent cold by hammering in a vise, However, the jaws should
have a slight radius to prevent serious weakening of the metal at the outside of the bend.
Rounding off the corners of metal parts is not necessary, but is a matter of craftsmanship. ALL
metal parts should be protected against corrosion by suitable painting, either with Zinc Chromate
Primer or a rust inhibitor like Rustoleum The best method is to have them cadmium plated.
* Out of print. Now sold by EAA along with many other "How-to-do" books.
viii
MISCELLANEOUS HARDWARE
The nuts and bolts are called out in the bills of materials, or parts lists, by the "AN" number,
meaning Army-Navy standard. These can be ordered from aircraft stores or mail-order houses by
the numbers, which have easily identified meanings. An AN-3-7A bolt is 3/16" in diameter as
indicated by the first number, which varies by sixteenths of an inch. The second number indicates
the length, the distance from under the head to the far end Of the threads in eighths of an inch.
However, 8/8 do not make an inch in this case. An AN-4-10 is a l/4" bolt one inch long and an
AN-5-11 is a 5/16" bolt 1-1/8" long, and so on. The letter "A" on tile end of the number means the
bolt is NOT drilled far a cotter pin. With no letter, it's drilled. All bolts used in FLY BABY are
cadmium-plated steel.
In aircraft installation, it is customary, but not mandatory, to install bolts with the heads pointing
either forward relative to the airplane, outboard or upwards. Where bolts through wood in FLY
BABY are loaded in shear, the area of the bolt is enough so that the hole doesn't have to be
bushed. The only bushings actually required are for protection in wear areas, as where wing,
attach bolts are frequently inserted and removed. When installing wide wood washers under nuts
or bolt heads that bear on wood, be sure to varnish the wood UNDER the washer before installing
it permanently. Except where specifically indicated, all nuts used in FLY BABY are AN-365 type
elastic stop nuts. Likewise, moving metal parts are joined by clevis pins secured with cotter pins
except as noted. Washers should be used between the cotter pin and the metal surface.
The 1600-pound-minimum strength turnbuckles are secured on the fork, end by clevis pins while
the wires through the eye are reinforced with AN-lO0-4 thimbles and secured with 1/8" Nico
sleeves. By using the same size of wire all over the airplane, the wire purchase and fastening
problems are simplified. It should not be necessary to buy a 1/8" Nicopress tool (they cost about
$22.00), for many mechanics and most aircraft repair shops have them. Turnbuckles are safetied
by either single or double wrap with #41 safety wire per Manual 18.
When buying nuts and bolts, washers, cotter pins. etc., don't get just the exact number specified
by the parts lists. No one ever has too many of these items. For AN-3 bolts and AN-393 clevis
pins especially, buy a good variety of lengths between the longest and shortest specified. No one
ever seem to have a surplus of AN-960-10 washers on hand, either.
A SUGGESTION
If you are completely inexperienced in aircraft matters, it is suggested that you associate
yourself with a local chapter of the Experimental Aircraft Association (EAA), a national
organization devoted to amateur aircraft builders. Write to Headquarters, EAA, 3000
Poberezny boulevard, Oshkosh, Wisconsin, 54903-3086. Membership is $35.00 per year, and
worth every cent of it for the magazine SPORT AVIATION alone. Write to EAA for the address
of the chapter nearest you. Practically all of the items you will need to build your FLY BABY
are advertised in the pages or SPORT AVIATION.
ENOUGH OF GENERALITIES! GET TO WORK ON YOUR FLY BABY!
ix
1 SECTION 1 - THE FUSELAGE
The all-wood fuselage of FLY BABY is both a simple and a rugged structure, and lends itself easily
to minor alterations to accommodate different landing gear, cockpit enclosures windshield, etc.
The main structural cross-members that support the landing gear are entirely independent of the
key wing-support structure, so these members can be moved around as desired without affecting
anything else. The turtledeck structure aft of the cockpit is removable so that flying is possible
with an alternate open cockpit or closed canopy arrangement.
Some people may be concerned over the absence of a "Turnover Structure" behind the cockpit.
Such an item cannot be installed without building up a structure above the pilot's head, which is
not compatible with the classic lines of this traditional open-cockpit design. Instead, the box-spar
vertical fin structure does this job and only breaking the fuselage in two will keep it from serving
its purpose of protecting the pilot should the plane go over on its back following a landing in
rough terrain.
The fuselage is built by making two side layouts on a flat surface just like a "Box" model airplane.
Much of the complex gusseting of older wood-truss homebuilt fuselages has been eliminated by
skinning each side with 1/8" plywood, which itself acts as a super gusset as well as adding
strength to the fuselage by its function as a shear web. In the nose section, a second inner
plywood shear web is added to help transfer the engine mount loads through bolts to the fuselage.
The arrangement of the fuselage truss members aft of the cockpit has been carefully chosen to
simplify the joint-and-gusset problem so that only two types of joints result. Because of the
plywood covering, the diagonal side members do not carry loads as they do in a welded steel or an
ordinary wood truss. Their main function is to support and stiffen the plywood.
Up forward, the main cross-load carrying members for the landing gear and wing supports are
built rigidly into the double bottom longeron structure of each side. By the time these are
anchored by the end blocks and inner plywood skin, NOTHING is going to move them. If you
manage to knock any one of these four main members loose you're going to need a whole new
airplane. The double longerons, boxed on both side with plywood, result in a "Double Keel" of
great strength for maximum safety. The heavy plywood gussets and metal fittings at the landing
gear attach points eliminate the need for diagonal bracing across the bottom in this area. It is
believed that the fuselage is adequate for 125 horsepower engines as presently designed. The only
problem is one of balance because of the increased weight of the larger engine.
Normally, fuselage structure is stiffened by diagonal members across each bay. This is impossible
in the area occupied by the pilot, so the problem is taken care of in the cockpit by the use of
quarter-circle corner bows covered with plywood, which serve the same purpose and leave the
spaces open.
The main fuselage structure is glued together, with various attachments bolted on. For maximum
strength and to avoid dependence on glue in such critical areas. the tail post and the front
bulkhead, which supports the engine mount, are bolted to the doubled main side structure
through metal fittings. Exterior wood surfaces are protected from the weather by fabric laid on
over the wood and all inside wood is varnished.
Page 1-1
FUSELAGE - BILL OF MATERIALS
WOOD
Number
4
124 ft
25 ft
7
120 ft
2
1
1
I
I
1
1
2
2
4
24
5
8
2
Material
plywood
spruce
spruce
spruce
any wood
spruce
plywood
plywood
plywood
hardwood
spruce
spruce
hardwood
spruce
spruce
spruce
spruce
spruce
spruce
Dimensions
1/8" x 4’ x 8'
3/4" (4 pieces 15', 2 pieces 7')
1/2" x 3/4"
1/4" x 1" x 6'
3/8" x 3/8" up to 15'
3/8" x 3/8" x 52"
1/4" x 4' x 4"
3/8 x 2' x 32"
3/4" x 2' x 4"
1" x 2" x 9"
3/8" x 2" x 12"
3/8" x 3" x 3"
3/4" x 1-1/2" x 20"
3/4" x 1-1/2" x 12"
1/4" x 1/4'" x 16"
1/16" x 3/4" x 36"
3/4" x 5" x 22-1/2"
1/2" x l/2" x 18"
1/2" x 2" x 4"
Use
Sides, gussets, etc,
Longerons, diagonals
Diagonals
Turtledeck stringers
Belly stringers
Fin flanges
Formers, anchors
Firewall former
Bows*, gussets
Tail spring anchor
Fin filler
Fin filler
Station I uprights
Station 11 uprights
Underfin flanges
Bows**
Station 2-54 X-pieces
Floor beam flanges
Hinge tube supports
.
HARDWARE
2
14
14
1
7
7
4
4
16
7
7
23
36
72
7
*
**
***
dural or steel
bolts
nuts
steel
bolts
washers
steel
aluminum
bolts
bolts
nuts
nuts
nutplates
wood screws
nails
Weldwood glue
cotter pins
1/8" x 1-1/2" x 22" rt angle
AN-4-14A (or longer) ***
AN-365-428
.063(or more) x4-1/2" x 10-1/2"
AN-3-12A
AN-960-10
.093" x 3-3/8" x 5-1/8"
1/2" x 1" x 3-3/8"
AN-3-14A
AN-6-16
AN-310-6
AN-365-1032
AN-366-F-832
AN-545-4-4
Engine mount anchors
Attach above
Tail post anchor
Wing wire anchors
Wing wire anchors
Cowling hold down
Hold nutplates
1/2" #20
AN-380-3-3
Alternate to building up laminated bows.
Alternate to expensive 3/4' plywood.
See Figure 1-16 for alternate installation.
Page 1-2
FUSELAGE LAYOUT
The main requirement for building the fuselage is a flat working area at least 2-1/2. x 15 feet,
preferably a bench that nails can be driven into. The shop floor will do if a couple of 34'" plywood
sheets are butted together and laid down.
1.
Using the dimensions of Figures 1-1 and 1-2, lay out a full size fuselage side view, using the
top of the top longeron as the reference line. The curve of the bottom longeron is drawn most
easily by using one of the longerons themselves as a drawing spline.
2.
Cut about 60 hold-down blocks from 1/2" plywood, 1" x 3". Having the blocks thinner than
the fuselage members allows the plywood skin to be laid on the fuselage frame while still held
by the blocks and if made of plywood the small blocks will not split when nailed down.
3.
Put the top longeron in position and hold it with enough pairs of blocks as shown to hold it
securely. Do not have the blocks too tight or it will be hard to lift the completed frame out of
the blocks. By using the same blocks twice without moving them both side frames will match
exactly.
NOTE
Put pieces of wax paper on the board at each glue joint to keep the
glue from sticking the frame to the board.
4.
Put the lower longeron in position, starting at the rear with pairs of blocks and working
forward. Note the extra length ahead of the forward upright (Station 1), held by an extra pair
of blocks, to give leverage for the final bend. More "Inside" blocks will be used on the curve
than "Outside" blocks. The pair of blocks "X" is located as shown at the end of the straight
section of the lower longeron. Block "Y" is located at the key point for forming the bend in the
longeron.
5.
Put in the intermediate (straight) lower longeron between Stations 1 and 6, holding it with
pairs of blocks. After a snug fit to the lower longeron at Station 6 is obtained, remove the
longeron and glue to the ends, and reinstall. Cut and fit in 3/4" plywood filler block per Detail
A of Figure 1-1 and glue in place.
6.
Cut and install the uprights between the lower and upper longerons at Station 3 and 5
through 8, holding 'each with two pairs of blocks. The fit should be such that the uprights
must be pressed into place but not forced hard.
NOTE
Glue on butt joins like these does not strengthen the structure or hold it together, it merely seals
the open end grain of the wood.
Page 1-3
Page 1-4
Page 1-5
Treat the Station 9-10 diagonal as an upright, using two pairs of holding blocks. See Detail H
of Figure 1-2 for spacing at Station 9. Notice that the upright at Station 6 is 1/8" thinner than
all the others as shown in Detail F of Figure 1/2, and that the Station 3 and 5 pieces between
the two lower longerons MUST line up with the upper pieces. Do NOT install the 3/4" x 11/2" upright at Station 11 at this time.
7.
Cut and fit the forward Station 1-2 diagonal. When properly fitted, only one block is needed
to hold it in place. Repeat for the Station 3-4 diagonal.
8.
Cut and fit the Station 2-3, 14-5, and all the remaining diagonals toward Station 10. If cut
and fitted properly, no blocks will be necessary to hold them in place. All diagonal aft of
Station 6 are 1/2" x 3/4".
9.
Fit a piece of 1/8" x 1-1/2" plywood over the thin upright at Station 6 and glue it in place per
Detail F of Figure 1-1. Hold with nails until the glue dries.
10. Cut a piece of 1/8" plywood from a standard 4' x 8' sheet to slightly over the dimensions from
Station 6 to a few inches aft of Station 11. Be sure that the top edge is straight, and square the
forward edge (Station 6) to it.
11. Lay this plywood on a suitable open-end work area like a workbench or table-saw table and
scarf a 12:1 bevel along the Station 6 edge per Detail F of Figure 1-1. This can be done with a
sharp block plane, a good draw knife if you are good, or with a "Scotch Plane".
12. Lay the plywood in place to be sure that it fits. If it does, hold it down with a couple of
aircraft nails driven in part way, and lay out the centerlines of all the structural members that
the plywood will be glued to. The easiest way to do this is to project the centerlines of the
diagonals and uprights beyond the structure onto the work surface before the plywood is laid
down. Centerline for upper longeron can be located by measuring in from the edge. The same
process can be used for the bottom longeron if the lower edge of the plywood has been
trimmed to it.
13. Make up at least two nailing strips 23" long per Figure 1-3, with nails started at
approximately 1-inch intervals. These are for use in the splice area. Some really meticulous
builders use nailing strips everywhere to hold plywood to structure only until the glue sets,
but it is hardly worth the effort for a design like this. At this station, the nails must be
removed because another piece of plywood goes over the joint.
14. Cut two pieces of 5/8" x 1/2" wood to fit under the plywood splice plate at Station 6 as a
backup for the nailing.
15. Mix up enough glue to cover all the structure from Station 6 aft and get it on the frame FAST
with a 1/2" to 1" paintbrush.
16. Lay the plywood in place, and start nailing. Approximately 1-inch spacing for 1/2-inch No. 20
nails is about right. Don't bother to actually measure this spacing. PUT WAX paper under
one nailing strip and use it to hold down the very forward edge Of the bevelled edge of the
plywood at Station 6. The nails should go through the bevel about 1/4" in from the edge.
Actually, the nails make the wood strip act as a long clamp.
Page 1-6
Page 1-7
17. While the rear plywood section is setting up, prepare the forward section in the same way.
Notice that the bevel is on the INSIDE face of the plywood this time!
18. Apply the forward plywood the same way after pulling off the nailing strip, but use two
nailing strips at the splice, one with the nails about 1/4" in from the edge and the second
immediately forward of the first. Because of the glue that will squeeze out of the joint, wax
paper under the strips is essential to keep them from getting glued down.
19. Remove the plywood-covered fuselage side frame from the blocks. Trim the plywood if the
edges are ragged, but leave at least 2" aft of Station 11.
20. Make a second side frame inside the blocks nailed dawn for the first. Fitting the diagonals will
be a somewhat more exacting job this time as the blocks are already there and will not be put
in position after the diagonal has been fitted. Remember that this second frame is for the
RIGHT HAND SIDE, so the plywood splice plate at Station 6 will be against the table instead
of on top of the frame.
21. Since the plywood goes on the "Down" side of this second frame, the frame will have to be
removed from the blocks before the plywood is applied. However, the butt-glue-joints will
not hold it together for this rough treatment, or even against the tension of the curved lower
longeron. Cut some scraps of 1/8" plywood and nail them over the various joints as gussets.
Do not use glue, but drive one l/2"-20 nail for each frame member in all the way. The whole
gusset, nails and all, can easily be pulled off later.
22. Remove the gusseted frame from the blocks, turn it over on a flat surface and apply the
plywood as in Steps 10 through 16. When putting temporary backup wood under the plywood
splice plate of Station 6, don't forget to add the thickness of the temporary gussets that are
raising the frame a bit above the work surface.
FUSELAGE ASSEMBLY
Before starting to assemble the fuselage, cut 16 quarter-round "A" gussets from 1/8" plywood and
26 half-round "B" gussets per Details A and B of Figure 1-4. Cut 12 3/4*" corner bows per Detail
C. All are simple arcs of circles with radii as indicated.
Next, cut five fuselage frame spreader bars from any convenient size pieces of wood and notch as
shown in Detail D of Figure 1-4. The fuselage is now ready for assembly.
Page 1-8
Page 1-9
1.
Lay three spreader bars on a flat surface, and fit the fuselage sides into them UPSIDE DOWN
as shown in Figure 1-5. Add the two remaining bars to the "Top" with the rear one at Station
5.
2.
Square the sides and the front end as shown, and after a double-check of the nose from the
opposite side to be SURE that it is square, tack on two cross-strips of wood aft of Station 6 to
assure the rigidity of the structure.
3.
Build up wing support Stations 3 and 5 according to Steps A through D of Figure 1-6. The
curves for the plywood faces of Step D can be marked to size by notching the straight sections
to fit and then penciling around the corner bows. Be sure to varnish the areas inside the
structure before putting on the second piece of plywood.
4.
Landing gear support Stations 2 and 4 are built up the same way except that corner bows are
not used. Do not build in Station 2 until after the firewall is mounted.
5.
The shapes and locations of the various 3/h" plywood filler blocks that anchor the Station 2
through 5 cross members to the lower double-longeron structure are determined from the
details of Figure 1-7 as keyed to Figure 1-1. The dimensions are not critical, but should not be
less than shown. Note that the blocks at wing support Stations 3 and 5 are notched out 3/16"
to allow the wing fittings to slip through. The holes in the rear blocks at Station 3 for the
aileron push rod are a bit under-size at this stage deliberately.
6.
Glue the blocks to the outer plywood skin after pressing them tightly against the plywood of
the cross-members per Step E of Figure 1-6.
7.
Cut and fit 1/8" plywood to form an inner covering for the double lower longeron structure
per Step F of Figure 1-6. Don't forget to varnish the insides before putting on the plywood,
and then drill a vent hole at the bottom of each closed area. It is best to drill the hole in the
plywood before you put it on.
NOTE
The work of Steps 3 through 7, above, results in Box Structure, which should be
inspected and approved by an FAA inspector before being closed up. He may not
insist on it for this particular piece of structure, but it is YOU responsibility to notify
him. Show him the drawings way ahead of time, and you might not be held up at this
point
by having to wait for his approval.
[The above note is included for historical purposes. The FAA no longer requires these kinds of
inspections. RJW]
8.
Mark the location of the wing spar pin holes on Stations 3 and 5 per the cross-section views of
Figure 1-9. They can be drilled at this time, but it is a good idea to wait and see if the wings
line up properly.
9.
With Stations 3 through 5 in and anchored, the structure is now sufficiently rigid to allow
removal of the spreader bars so that it can be turned over for working at more convenient
angles.
Page 1-10
Page 1-11
Page 1-12
10. Starting at Station, 6 and working toward the tail, cut, fit, and install the 3/4" square cross
pieces and diagonals per Figure 1-8, using the half-round "B" gussets of Figure 1-4 nailed and
glued to the OUTER faces of the longeron ONLY. The gussets at Station 6 are only temporary,
and are nailed in place but not glued. Do not install cross pieces aft of Station 8 at this time.
11. Starting again at Station 6 and working aft, install the diagonals per the cross-section views of
Figure 1-9 with two type "A" gussets at each end per Detail A of Figure 1-4. Note 3/36" holes
drilled for drainage. Cut 3/4" square notches in the middle of Type "B" gussets and doublegusset remaining Figure 1-8 diagonals per Detail B of Figure 1-4. Drill drain holes in bottom
gussets of lower longerons before installing notched top gusset.
12. Build up the rudder post per Figure 1-10. Lay out the proper shape on a piece of 1/8"
plywood and cut to exact outline. Glue a 3/8" square strip of spruce down each side. Since it
can't make the sharp bend at the bottom, let it project straight, and fit bottom piece of 3/8"
solid wood as shown. Add 2-inch filler blocks to back-up hinge bolts where shown, and glue
on top plywood. This is again Box Structure, requiring inside varnishing and FAA approval
per Note of Step 7.
13. Using C-clamps at top and bottom, clamp 3/4" x 1-1/2" uprights temporarily in place at
Station 11 (the upright on the left side is 5/8" x 1-1/2"). Bevel the rear edges so that they fit
squarely against the rudder post when it is held in place. The sides of the rudder post will
also have to be beveled so that the plywood projecting past the Station 11 uprights fits the post
snugly.
14. Cut a piece of 1/8" plywood to fit the area between the Station 9-10 diagonal and the rear of
the Station 11 upright, and glue it in place on the LEFT inside of the fuselage. The purpose of
this is to reinforce the plywood so that an access hole can be cut in later.
15. Using C-clamps from the top and the rear, glue in the Station 11 up rights. While they are
drying, clamp and glue in the two half-round 3/4" plywood blocks of Detail I, Figures 1-2 and
1-11 and glue 2" triangles of 3/4" plywood into the Station 9 corners per Figure 1-11.
16. After the clamps of Step 15 have been removed, glue and clamp in the rudder post, being sure
that it is perpendicular in both axes. While it is drying, add the 3/4" square cross piece shown
21" ahead of the rudder post on the top longeron layout of Figure 1-8 and cut and fit the
Station 9 1" x 2" hardwood tail spring bolt support. Anchor this with 3/4" plywood triangles
notched and fitted per Figure 1-1l.
17. Fit 3/4" square cross pieces between top and bottom longeron pairs tight against the rudder
post per Figures 1-8 and 1-11. Because of the slope of the lower longerons, it will be necessary
to bevel the bottom cross piece so plywood can fit across the longerons later. Clamp the cross
pieces to the rudder post while the glue dries.
Page 1-13
Page 1-14
Page 1-15
Page 1-16
Page 1-17
18. Bend up a sheet of .032 steel so that it just fits the tailpost/fuselage intersection. It is held on
each side by three 3/l6" bolts through the outer plywood and the uprights, and through the
tailpost by the two lower hinge bolts and one other as shown in Figure 1-11. Be sure to varnish
the wood under the anchor before installing it, and paint or cadmium plate the anchor. See
Also Figure 1-2, cross-section B-B.
19. Install the 3/4" square cross piece shown 7" ahead of the rudder post on the top longeron
view of Figure 1-8 and Figures 1-11 and 1-12. Note that this is cut half-way through from the
bottom for control cable clearance. Cover the area from the previously-installed cross piece
21" ahead of the rudder post to the rudder post with 1/8" plywood in TWO PIECES, butted
together on the centerline of the 7" crosspiece. The purpose of the crosspiece is to stiffen the
plywood ahead of the cutout in the piece of small plywood that is cut out per Figure 1-12 to
allow the elevator horn to protrude through. Nail and glue 1/8" plywood below the lower
longerons from Station 9 to the rudder post AFTER the underfin side plywood anchor stripes
have been nailed and glued in place per Figure 1-13. Drill drain holes in the bottom plywood
at the corners of Stations 9 and II and trim plywood flush with sides of longerons.
20. Build up the underfin structure as shown in Figure 1-13. The 1/4" square flanges provide side
surface for the plywood side pieces to be nailed and glued to. Note the cutout at the rear
center of the bottom rib to allow access to the tail spring support bolts that go through the
bottom of the tail post.
FUSELAGE SECONDARY STRUCTURE
The secondary fuselage structure consists of those parts added after the main framework has been
assembled per instructions in the earlier portions of this chapter. Since most of these are not
primary load-carrying parts, the builder has great leeway in the use of sizes and materials other
than those specified. The "Turtledeck" around and aft of the cockpit (see Section 6) was designed
to be removable and interchangeable with an enclosed-type canopy structure, but either type of
structure can be built on permanently if desired. An item like the forward slope of the instrument
panel is entirely arbitrary. Tall pilots would probably prefer a greater slope while short pilots
would want it more nearly vertical.
1.
Cut firewall Former No. 1 from 3/8" plywood per Figure 1-14 and the three top fuselage
formers at Stations 6, 7, and 8 from 1/4" plywood. A strip of wood with a nail as a pivot and a
hole for a pencil makes a good compass to swing long arcs of circles (Figure l-15).
NOTE
The lower portion of the No.1 Former on Figure 1-14 is out of scale, so use the
dimensions as written.
Page 1-18
Page 1-19
2.
Build up a 3/4" wide by 3/4" deep flange on backside of top portion of Former No.1 per
Figures 1-14 and 1-15. The only purpose of this is to serve as a base for the nutplates that
anchor the forward metal turtledeck, and can be built up of scraps of 3/4" plywood trimmed
to fit or can be laminated as a single bow by tracing the curve off on a work surface, drawing a
line set inside 3/4", driving nails along it, and laminating strips of 1/l6" x 3/4" wood in place.
3.
Glue in Former No.1. After it has set, trim the excess side plywood and install the landing
gear support at Station 2 per Figure 1-6. When installing the inner plywood between Stations
1 and 2, carry the plywood upward along the diagonal per Figure 1-15.
4.
Cut a 1/8" x 1-1/2" x 1-1/2" 2024 dural angle, trimmed flush with the top and bottom
longerons, to fit the firewall corners per Figure 1-16. Do not drill or install at this time.
NOTE
If you have difficulty getting dural angle, the weight penalty is negligible if you use 1/8"
mild steel angles easily obtainable from most metal supply stores. An alternate is to bend up
3/32" or 1/8" sheet steel, but this job will probably have to be done at a metal shop where a
22" piece can be bent on a brake.
5.
Install Formers 6 through 8 on the BACK SIDES of the 3/4" top across pieces at those
stations, and glue in the six 1/4" x 1" stringers. Don't try to save weight by making the
stringers any thinner. Note from Figure 1-15 that the forward ends are notched to take a
2"strip of 1/8" plywood.
6.
Fit the plywood strip to the stringers at Station 6 by laying an over-size strip, GRAIN
PARALLEL TO STRINGERS, in place and marking the forward edge by using the front of
Former 6 as a guide. Measure back 2 inches for the rear line, trim, and install. The fabric will
have a smoother appearance if the plywood is scalloped per the dotted lines of Detail A,
Figure 1-15, after installation.
7.
Build up box-construction seat support beams and install with triangular glued and nailed
corner blocks per Figure 1-17.
Note positions of rudder cable holes, control stick bearings, and belly stringers for future
reference.
8.
Install combined floorboard beams and wing hinge tube supports between Station 2 and 3
per Figure 1-18. The holes for the 1" I.D. tube can be drilled any time, but it is easiest to do it
now, before the beams are installed. If the tubes are installed now, be sure to leave the
matching fitting on the wing root undrilled until the wing can be installed on the fuselage and
proper alignment of the tube and the hinge assured.
Page 1-20
Page 1-21
Page 1-22
Page 1-23
Page 1-24
NOTE
The wing hinge support-tubes can be metal or fiber. Fiber tubes can be glued or
cemented in place with Goodyear Pliobond or equivalent while soft aluminum tubes
can be cut about 1.8" over-length on each end and the ends can be peened over to
hold them in place.
9.
Make metal wing support assembly per Figure 1-19. For best quality work and permanence or
corrosion protection, fittings should be sandblasted and then cadmium plated. Painting with
Zinc Chromate or Red Oxide primer and then a coat of lacquer or enamel will do almost as
well at less cost.
10. Install wing wire support assembly at Station 3 as shown in Figure 1-20. Drill through the
fittings to put 5/16" bolt holes through the wood, then remove the fittings. It is easier to drill
the holes now than after the next steps.
NOTE
Cut a scrap of 1/8" plywood 1" wide to go under the bottom aluminum pad of the
fitting before installing it on the fuselage because the permanent top plywood has not
been installed at this stage.
11. Add the cockpit corner bows in the cockpit as shown in the top view of Figures 1-8 and 1-20.
12. Add a 3/4" x 1" spruce cross piece ahead of Station 3 as shown by "A" in Figure 1-20, notching
the aft side at the ends to fit the wing wire support assemblies. Bevel the forward side of this
3/4" x 1" piece to allow plywood instrument panel to slope forward so that top is 1-1/2" to 2"
ahead of bottom.
13. Cover the area on top of the fuselage from Station 6 to a point just forward of the rear cockpit
corner bows with 1/8" plywood per figure 1-20 and the top view in Figure 1-8. The area from
the piece "A" ahead of Station 3 aft to the other plywood can be covered with two separate
pieces. Note slots for wing wire support assemblies in Detail B, Figure 1-21.
14. Make outline bow for instrument panel to be installed forward of 1" wide cross piece "A" at
Station 3. This can be cut from 3/4" plywood per the curve shown on Figure 1-21 or can be
laminated from thin strips of wood around a row of nails corresponding to the inside curve.
15. Assemble 3/4" square cross piece and uprights with temporary 1/8" plywood gussets nailed
to FORWARD side. If you have your instrument layout decided on at this stage
(requirements and installation details in Section 6), cut holes for them in the two side 1/8"
plywood panels and nail and glue the panels to the bow and the two uprights without
bothering with the temporary gussets. When using the gusset method, build the frame
reversed, with the 5-3/4" panel at the LEFT. The left panel is wider because it takes more
instruments. When fitting and gluing on the panels notice that the plywood edges come only
to the CENTER LINES of the uprights. The center panel is removable, and the mounting
screws are anchored by four nutplates fastened to the forward side of the bow with wood
screws as shown in Detail A of Figure 1-21.
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16. With the side plywood panels glued in place, install the panel assembly in the fuselage by
gluing the portion of the side panels below the 3/4" square cross piece to the forward side of
the 1" x 3/4" beveled cross piece "A" installed in Step 12 and Figure 1-19. The ends of the bow
should be beveled to accommodate the forward slope of the panel.
17. Make quarter-round gussets of 3/4" plywood for the intersections of the bottoms of Stations 2
and 4 with the fuselage sides. With half-round 1/8" plywood gussets (Type "B", Figure 1-4)
already in place, the curves on the 3/4" gussets can be made by tracing around square blocks
held in place in the corners. Glue the 3/4" gussets in place by clamping against the 1/8" Type
"B" gussets (see Figure 1-17). These 3/4" gussets serve as supports for the inside landing gear
anchor fittings.
FUSELAGE BELLY STRINGERS
The two full-length belly stringers are fuselage structure, but for convenience of doing other work,
should not be added until the inside is varnished, all equipment is installed, and the fuselage is
ready to cover. Because the stringers are deep and narrow and take a significant curve at the
forward end, each stringer is laminated in place from five thicknesses of 3/8" square wood. This
can be spruce, redwood, fir, or pine.
1.
Glue two 3/4" square anchor blocks to the back side of the firewall as shown in Detail "B" of
Figure 1-22.
2.
Start building up stringers with 3/8" square strips. The bottom two will be full-length from
the firewall to Station 9. The second one will be tapered after others have been added per
Detail "D", Figure 1-22. See Figure 1-17 for spacing in the cockpit area and Detail "C" of
Figure 1-22 for method of attachment. First strip can be laid down by nailing and gluing
directly to the fuselage cross pieces.
3.
When stringers are built up to full depth, use a plane or drawknife to taper them from Station
5 to Station 9, ending up with one full thickness per Detail "D", Figure 1-22.
4.
Use scrap wood to fill in triangles between the stringers and the longerons at Station 9 per
Detail "D" of Figure 1-22 and do the same at Station 2 using wood at least 1/2" thick between
the stringers and from the stringers to the longerons. These will became the forward anchors
for the belly fabric during covering.
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MAJOR ATTACHMENT DETAILS
Some confusion as to "What Fits Where" has resulted from the serialized presentation of FLY
BABY plans in SPORT AVIATION magazine (starting in January, 1963) and the delivery of plans
by chapters to early purchasers. Without a single overall assembly or drawing, or all of the major
section drawings together at one time for comparison, a misunderstanding of the functions of
various parts is inevitable. To offset this, the supplementary drawing presented above has been
prepared to show how and at what points the wing, landing gear, and other components attach to
the fuselage.
The wing spars attach to the bottoms of Stations 3 and 5 by means of 1/2" pins passing through
the end fittings and the wood. The landing gear vee's attach by means of AN-4-44 bolts at Stations
2 and 4. The seat rails of Figure 1-17 are mounted between Stations 4 and 5, and the combined
floor and wing hinge tube supports of Figure 1-18 are between Stations 2 and 3. The control stick
torque tube bearing blocks are mounted on the aft side of Station 3 and the front side of Station 4
as shown in Figure 1-17. The upper wing wire anchors and the instrument panel are mounted at
the top of Station 3 per Figures 1-20 and 1-21. The throttle is mounted through the lower inside
bolt hole of the left-hand wing wire anchors.
End of Fuselage Section
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