Hannan was a prolific designer of and author of magazine articles
and books about free flight models. His contributions spanned more
than fifty years. Many of his designs, like the Flyangle, targeted
beginners. His goal was to present models that were easy to build
and that were constructed in such a manner as to virtually guaranty
success. Based on the inherently rigid, warp resistant triangular
features of the AMA's Delta Dart, Hannan's Flyangle introduces a
built-up fuselage with a triangular cross-section. It is the next
logical step up from the Delta Dart. Airplanes and Rockets website
visitor Ray M. wrote to request this article. It's nice to know
there are still purists out there building these models.
added realism this rubber-powered cutie is a slightly advanced version
of the basic Delta Dart.
Probably the most influential simple model of this decade has been
the Delta Dart. Designed by AMA Technical Director Frank Ehling,
the model was published in the much-lamented "Sig Air-Modeler" magazine
during 1966. It was known at the time as the "AMA Racer." In April
of 1967, American Aircraft Modeler featured plans under the name
"Delta Dart," which seems to have been the most widely accepted
name for the species. A modified version kitted by Sig Mfg. Co.
is called the "AMA Cub." A larger, glow-engined variation called
"Oily Bird" appeared in the Oct. '68 issue of American Aircraft
Modeler, and in fact, full-size plans for it are still available
through Sudden Service Plans.
Off it goes into the wild-blue yonder, the North Pacific Sleek
Streek prop churning away on one loop of 1/8" rubber. The intent
aviatrix demonstrates just-right launching.
It has its good points - all over the place. Delta Dart-type
wings and tail minimize dangers of warps in the surfaces. That's
important if it is to fly successfully.
Simple wing mounts and rubber-band attachment show clearly here.
Wing slides back and forth for making necessary corrections
in balancing. Article describes how to adjust model.
Wing frame is built directly on covering paper, as with Delta
Dart. The wing mounts are 1/16" sheet balsa with 1/16" dowels
attached. Rubber bands wrap around dowels and body.
Even the fuselage has a triangular motif. Because it has a flat
top, it can be assembled inverted on your board. Nothing can
be simpler. Rubber is inserted with a stuffing stick.
"Flyangle" represents an effort
to produce a slightly advanced version of the basic idea, incorporating
a fuselage and other items intended to add a degree of realism.
While the model is not as simple to construct as the Delta Dart,
anyone who is willing to work carefully should be able to produce
an attractive, flyable aircraft.
Medium-hard balsa can be used throughout, with the exception of
the fuselage longeron, nose block, and wing mounts, which should
be made of hard balsa. When selecting wood for the job, choose straight,
warp-free pieces, which may be found by sighting down each strip
from end to end.
Construction: Build the
model on a flat surface in order to prevent any built-in warps.
Spend a few minutes looking over the plans and photos to be sure
that you understand the relationship of the parts. Since the plans
are printed full-size, you may build directly over them. A sheet
of waxed paper or clear plastic food wrap will keep glue from sticking
to the plans.
Fuselage: Cut the fuselage
top panel from 1/16" sheet balsa, and sandpaper the edges lightly
to remove any roughnesses. Mark the position of each triangular
fuselage former on the panel, using a soft pencil or ballpoint pen.
Next, cut out the various formers. Since the fuselage is constructed
upside down, the top panel will actually be on the bottom during
the building stage, and may be held flat against your building board
with straight pins.
Glue each former in its correct
location, checking that all are vertical for proper alignment. Allow
the formers to dry, then add the 1/16" sq. hard balsa longeron,
which will need to be cracked at the rearmost F2 former, in order
to permit the change in angle at that point. Cut out and install
the triangular rear rubber-peg retainers. It is easiest to make
only a pin hole where the peg fits in each retainer, at first. Then,
enlarge the holes to proper size after the retainers are installed
and have dried. This will assure correct peg alignment. Add a second
coat of glue to the former and peg retainer joints, as they are
subject to strain when the motor is fully wound.
the fuselage assembly has dried, remove it from your building board
and sandpaper any rough places. By using a small sanding block or
emery board, it is easy to blend in any edges or corners that may
protrude. The time spent in doing this will make the task of applying
the covering much easier.
The landing gear legs are bent from a piece of .025-diameter music
wire, using needle-nose pliers. The wheels used on the original
model were plastic, but could just as well be wood. The size is
not too important, and anything from about 1/2" up to 1" diameter
should prove satisfactory. The wheels are retained by bending the
axle ends upward. For good ROG (rise off ground) starts, the wheels
should revolve freely. Note that the landing gear legs are bent
slightly to the rear to provide propeller clearance.
The landing gear wire is sandwiched between F1 and F1-A using plenty
of glue. A clothespin or two can be used to clamp the assembly together
while the glue dries.
Noseblock and prop:
The nose block can be made from a 3/16" -thick piece of hard sheet
balsa, with a 1/8" hard balsa sheet triangular plug glued on, or
the block may be laminated from 1/16" hard balsa sheet. In either
case, the nose plug should be a snug fit into F1, so that it will
not fall out during flight. The prop shaft bearing is a short length
of 1/16" -diameter aluminum or brass tubing. Note that it is mounted
in a slanted hole to provide 4-5 degrees of down-thrust. Roughen
the outside of the tubing with a file or sandpaper, and glue it
into the nose block. Be certain to clean out any glue that may find
its way into the inside of the bearing.
The prop shaft
may be formed from a piece of music wire, with the aid of needle-nose
pliers. Any suitable plastic prop from 5" to 6" in diameter may
be employed, but a North Pacific "Sleek Streek" prop was used on
the prototype. Add enough small washers or sequins to the prop shaft
so that the propeller will clear the corners of the nose block.
Also, apply a drop of oil to reduce friction.
Wings: The wing panel is constructed directly over
the plan from 1/16" -sq. medium-hard balsa strips, which are held
down while drying, with straight pins. Do not puncture the strips
with the pins, as that would weaken them. After the wing panel has
dried, it may be removed from the board, and a second one exactly
like it may be built.
The wing mounts are cut from
hard 1/16" balsa sheet, and glued to 1/16" -diameter hardwood dowels.
These may be obtained at low cost from a drug store, by asking for
"swab sticks." The rear rubber peg is also made from one.
Tailplanes: The tail parts are made from 1/16"
balsa strips in the same manner as the wing panels. Note that there
is an extra piece of 1/16" sq. at the lower front part of the fin.
Cut the small triangular sub-fin (which also serves as a tail skid)
from 1/16" sheet balsa.
There are several approaches to covering a model with tissue, but
our favorite is as follows: Apply several coats of clear dope to
each part of the structure where the tissue will be secured. The
use of a plasticized dope, such as Sig "Litecoat" will reduce the
chance of warping. Also, even though the wings and stab are only
covered on the top side, it is a good plan to dope both sides of
the structure to minimize warping, caused by the action of the dope
drying. The small amount of additional weight is more than offset
by the efficiency of good, true flight surfaces.
the dope has been applied (usually two or three coats are required),
cut a slightly oversize piece of tissue paper and place it over
the framework to be covered. Using a small brush, flow some dope
thinner through the tissue, along the previously doped structure.
The thinner will penetrate the tissue and soften the clear dope
film underneath enough to render it sticky. Do only a few inches
at a time, and press the tissue firmly against the structure. If
the tissue develops a bad wrinkle, apply thinner, pull it off, and
try again. Work your way around the entire outline, then put the
part aside to dry for ten or 15 minutes. The excess tissue may be
neatly trimmed from the structure, with a sharp razor blade. Check
for any areas that may have popped up or worked loose. A light application
of thinner and/or dope should take care of them.
is only necessary to cover the two fuselage sides, but we elected
to cover the top also to achieve a more uniform color scheme. The
wing and stab, as mentioned earlier, are covered on the top side
only. The fin would only need to be covered on one side, but its
appearance is much better when covered on both sides. The forward
cockpit portion of the fin is covered with cellophane. Don't forget
to put the paper pilot inside first.
covering may be lightly shrunk with water, but the wing and tailplanes
are left alone and not shrunk or doped.
Glue the fin onto the exact center of the stab and check to be sure
that it is vertical as viewed from the rear. After the fin has dried,
the tail assembly may be glued onto the fuselage. For greatest strength,
a small amount of tissue should be removed from the fuselage if
the top has been covered, so that the glue can grip wood rather
Sand a small flat into the rear portion
of the fuselage longeron so that the sub-fin can be solidly attached.
Glue the two wing panels together at the centerline,
raising one tip 4" off the board for dihedral purposes. A block
of wood can be used to hold the tip up while the glue joint dries,
preferably overnight. When dry, add the wing mounts. The rear (short)
mount glues on the underside of the wing trailing edge, while the
front (tall) mount glues on the underside of the small crosspieces
just aft of the wing leading edge. After the mounts have dried,
put a little extra glue into the crack along the bottom side of
the wing dihedral joint.
The wing is held in place on the
fuselage with two rubber bands. CAUTION: Do not use excessively
strong rubber bands, or the lower longeron may be broken. Only a
small amount of tension is needed to hold the wing securely in position.
Flying: Check the wings and tail surfaces
to be sure that they are not twisted. Happily, the nature of triangular
planforms is such that warps do not cause as serious a problem as
would the same amount of deflection on a normal wing design, but
severe warps or twists should be eliminated.
The power requirements
of individual models vary, depending upon the choice of propeller,
and the weight. Ours performed well on a single loop (two strands)
of 1/8" flat brown rubber, but it is recommended that you try different
sizes and brands until you arrive at the best combination for your
particular aircraft. A stuffing stick is the easiest way to insert
the rubber motor. It consists of a hard balsa 1/8" -sq. strip about
a foot long, with wires bound and glued on one end. With it, the
rubber loop can be inserted from the front of the model. If this
system does not work well for you, you may prefer the old-timer's
approach of leaving one fuselage space uncovered behind the rubber
retaining peg. A small weight on a piece of thread may then be used
to pull the rubber loop through the fuselage.
model is rather light, test flying should be performed on a calm
day, and if possible, over a soft landing field of some sort. Even
an ordinary lawn is more gentle to models than such unyielding surfaces
as asphalt or concrete! When gently launched from shoulder height
in a slight nose-down attitude, the model should neither dive nor
stall. If it does dive, slide the wing forward on the fuselage.
If the model stalls, slide the wing toward the tail. A 1/8" movement
should be enough to make a noticeable difference. If the model tends
to fall off on one wing, a simple cure is to affix a small lump
of modeling clay to the opposite wing tip.
When a fair glide
has been achieved, try winding in 50-60 turns of the prop and giving
the model a gentle hand launch. It is likely that a little right-thrust
may be needed. This is obtained by inserting a sliver of wood between
the nose block and F1, so as to point the propeller slightly toward
the right, as viewed from the rear of the model. Additional down-thrust
might also be needed, and a sliver of wood at the top of the nose
block will provide it. As power is increased, small changes in the
wing position and/or thrust shims may be indicated. Perform only
one adjustment at a time, so that you will know what not to do,
if things get worse! Once your adjustments are just right, it is
suggested that the thrust shims (if any) be glued permanently in
place, and that a mark be drawn on the fuselage to record the best
location of the wing. This is so that if the wing is shifted or
dislodged, it can be returned to the correct position.
to give "Delta Dan" part credit for your good flights - you can
tell by his nose that he is a sharp pilot!
Flyangle are available from the AMA Plans Service for $3.)
<click for larger
The AMA Plans Service offers a
full-size version of many of the plans show here at a very reasonable cost. They
will scale the plans any size for you. It is always best to buy printed plans because
my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the
Academy of Model Aeronautics - the #1
advocate for model aviation throughout the world. If the AMA no longer has this
plan on file, I will be glad to send you my higher resolution version.
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Posted October 21, 2012