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. It appeared in the March
1970 issue of American Aircraft Modeler magazine 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.
For 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
Materials: 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.
After 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.
Landing gear: 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.
Covering: 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.
After 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.
It 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.
The fuselage covering may be lightly shrunk with water, but the wing and tailplanes
are left alone and not shrunk or doped.
Assembly: 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 than paper.
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.
Since the 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.
Remember to give "Delta Dan" part credit for your good flights - you can tell
by his nose that he is a sharp pilot!
<click for larger version>
(The plans for the
are available from the AMA Plans Service for a mere $3.)
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.
Try my Scale Calculator for
Model Airplane Plans.
Posted July 27, 2022
(updated from original post on