is the article and plans for the "Insect" that I electronically
scanned from my purchased copy of the April 1970 American Aircraft
Modeler magazine. Rogallo Wings were all the rage in the 1970s as
hang gliding was really gaining in popularity, so the modeling world
joined in the fun. An article for the R/C
complete with a G.I. Joe pilot, was published four years after this
free flight model.
Plans for this fine model were drawn by
Bill Warner. Because they spanned two pages, I had to adjust the
size and alignment a bit to get the halves to line up properly.
They were printed full-size in the magazine, so to get the right
size when printing, you will need to do some trial and error. There
really is no need to even print plans, because dimensions for the
parasol components are shown, and the remaining few pieces can be
Watch out - it's really thermal happy!
Harold W. Warner
THE 135 degree sand, and the sharp weed stubble having just about
finished the soles of my bare feet, I thought to myself, "This is
a real Tenderfoot project." I had just retrieved Insect No.3 from
a 7½-minute flight across the Los Angeles River. (The original model,
using a 10" loop of Pirelli rubber vanished 2,000 feet high after
14 minutes. Editor.) My shoes, left on the bank for easier fording,
had disappeared when I returned, precious thermal-riding Insect
in hand. The difficulty of explaining this to my wife as I limped
home was almost as hard as explaining to the uninitiated why such
a simple flying machine could do such fantastic things!
Chrome Mylar flasher on pylon makes model visible when 600 feet
in air. This Insect flew for 7'/2 minutes.
Bill Watson holds his own flying-wing type model in right hand,
author's Insect in left. Holes in pylon were punched two at
a time until correct power turn obtained. Big pylon overcomes
left turn due to prop torque.
Watson launches Insect No. 3 for power climb on 5/32" Pirelli
Rear view of No. 3 shows markings which make it so impressive
in flight. Use Marks-A-Lot felt pens of different colors.
The Insect was developed as a RogalloWing demonstration for a class
I was teaching in Flying Machines at the junior high school level.
It grew out of Ron Moulton's "Project Parasol" in Aeromodeller
and an excellent article in the 1964-5 Zaic Annual by John Worth.
The Rogallo-Wing (parawing, sailwing, flex-wing) was tested by NASA
with an eye to space vehicle reentry, but really makes a bang-up
crowdpleaser which gives a high return on your investment!
The secret of this machine is the proper center-of-gravity (CG)
location. Many modelers forget that the center of gravity is a three-dimensional
thing and not just a point on the wing where you balance your Piper
Cub "front-to-back." Actually, the CG is the point where the model
balances in any direction, and the vertical or "up-down" position
must be taken into account on the Rogallo-wing design. A lower CG
tends to give the same anti-stall effect as a forward CG, and is
obtained through the use of long landing gear with wheels or clay
a long way below the fuselage. The landing gear can be made shorter,
but you will have to use heavier wheels to compensate and keep the
CG where it belongs: on the thrust-line (right where the rubber
Building the Insect is super-simple. The flexible
wing is begun by taping one layer of thin dry-cleaner bag to a table
top. Actually, you may save time by making a pattern and placing
it underneath, to guide you in contact-cementing the keel and sides
in the right places. Cut three 1/8" sq. spruce sticks and contact
cement them onto the plastic in the arrowhead shape shown in Fig.
Cut the cross brace from the same material and cement
with Ambroid or other quality model cement to the keel (center stick.)
Do not cement it to the plastic or to the wing edges - just keep
it at right angles to the keel while it dries. Cut the pylon and
gusset from soft sheet, keeping grain direction as per plan. Cement
pylon assembly to keel as in Fig. 2, then take it off the keel,
and let cement dry. This pre-coat is important for a strong butt-joint.
Glue it on again; make sure it does not lean to the side while drying
(a baby-food jar block on each side works fine for this).
In about a half hour, finish wing by untaping plastic and moving
wing-edges into the 9" dimension shown in Fig. 2 and cementing cross-brace
to edges (but not to plastic.) Trim excess plastic, leaving a bit
at the nose to fold over for extra strength. Remember, contact cement
sticks plastic on, but Ambroid doesn't.
You can build your
own fuselage or use one from a North Pacific "Sleek Streek" cheapie
flyer. The prop assembly from this plane works O.K., but bending
a deeper prop shaft and putting in a glass bead will keep rubber
from climbing off the motor hook and will cut friction and wear
to a minimum. If you use the stock front end, be sure and oil the
shaft, use shorter motors, and keep rubber lube away from the hook.
A bent pin hook works better than the staple you get with the Sleek
Streek for keeping the rear of the motor in place.
1/32" diameter music wire landing gear and thread-wrap, rubbing
cement generously into the wrapped area. Wheels are also from the
Sleek-Streek. Now give your cannibalized Sleek-Streek kit to the
neighbor kid who will make an unsuccessful glider out of the parts
that are left. All that remains is to mount the pylon on the fuselage,
taking care to "double-glue" it for strength as before.
Decoration of your Insect is up to you. Felt permanent marking pens
do a nice job on the plastic for a colorful, transparent color scheme.
Chrome mylar tape was used on the pylon sides and propeller tips
for visibility when the insect is over 500' up. You'll need them
on those good thermal days.
Test fly your Insect on about
a 9" loop of 1/8" Pirelli rubber lubed with glycerin. Wound from
the rear with a bent nail in a hand drill, about 100 turns should
do to start with. You can build up gradually each flight if the
Insect flies well. Should the Insect stall or loop over the top,
add a .little clay to each front wheel. If it dives sharply or refuses
to climb, add a little to the tailskid.
A tendency to dive
in to the left under power may be corrected by bending a little
right-thrust into the nose-piece which will pull in the opposite
direction from the dive side. Also check that the pylon is on straight.
If the pylon is twisted, it may be necessary to steam it and twist
it in the opposite direction. If the Insect persists in diving after
all your efforts have failed, bend the keel slightly up ahead of
the pylon (it may have warped downward).
general, a launch with the nose slightly up is desirable, but under
high power, the nose pointing straight up works best.
high-performance Insect can be made by reducing weight wherever
possible by using lighter materials - 5/32" Pirelli will give a
real climb! If the Insect does aerobatics under high power, try
a longer motor, less-powerful motor, adding clay to the wheels,
giving the wing edges more sweepback angle for more stability (at
the cost of lift). Adding clay judiciously to one wheel or the other
Be sure and put your phone number on your
Insect if you want it back! If you want to try designing your own
Rogallo-wing and don't like guessing, John Worth has worked it all
out for you in the 1964-5 Zaic Yearbook available from: Model Aeronautic
Publications, Box No. 135, Northridge, Calif. 91324.
<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.
Try my Scale Calculator for Model Airplane Plans.
Posted June 11, 2011