Replica 2016 from Russia

RIC Contributing Editor Bob

Hobby Bam's Aberle tries his hand at an all­
out Pattern ship in glass and

Curare
foam. It uses an OS .61 for
power aided by a Mac's pipe and
manifold and sports Sonic Sys­
tem's pneumatic retract gear.

or the past seven years I have been writ­ past winter I decided that it was about time system". All ofthe items reviewedwere solic­
F ing product reviews for Ft,YINCMODELS. to try pattern once again, if only to maintain
My basic charter as Contributing Editor is to credibility as an "all around RIC modeling
ited byrne. Or, stated another way, they were
all my ownpersonal choice.For the aircraft I
review all the latest RIC equipment and ac­ author". I decided to select some ofthe latest decided on the Curare design of Hanno
cessories. During that time span I did man­ "state-of-the-art" equipment for my review. Prettner.1t is probably one ~fthe best exam­
age to also design and publish approximately Was it easy to get back into pattern? Has the ples of current "state-of-the-art" pattern
a dozen original RIC models. In my design technology changed? Read on, you might be competition models. and is recognized
work I try to vary the subject matter each surprised about some of my comments and throughout the world. Insearching for a kit I
time to maintain reader interest. As such my experiences during this project. decided that I wanted to try my hand at
designs to date have included everything This review will actually cover four prod­ fiberglass fuselage/foam wing construction. I
from a Cox.010 powered, two-channel model ucts (the airplane kit itself; the engine; tuned was also looking for a designer approved kit
to a large eight-pound RIC seaplane. I have pipe and retract system). In addition I will which reflected the original Curare design
been asked quite often why I don't fly pat­ comment on the performance of the radio (as close as possible). My selection zeroed in
tern. Well I did, as a matter of fact, fly pat­ system (in this specific application); on on the Quality Line Kits as manufactured
tern years ago. My last pattern model was finishing techniques and how everything and distributed by Hobby Barn. For the en­
the Bridi Kaos which I flew up to 1973.This was integrated into an "RIC pattern aircraft gine I wanted something very powerful in a
.60 displacement with a precision type car­
buretor, but at my choice I did not want a
pump system. I decided on the new World
Engines OS Max .61 FSR. For the tuned pipe
system I selected the items manufactured by
MAC's Products. Finally came the choice of
the retract 'landing gear mechanism. I was
quite undecided between an air operated sys­
tem or an electric. My final selection was the
new air system manufactured by Sonic Sys­
tems.

Hobby Bam Curare Kit

At the time this kit was obtained Hobby
Barn, P.O. Box 17856, Tucson, Arizona
85731 was offering the standard (or original)
Curare design. As close as I can tell it is
identical to Hanno Prettner's design which
was published in the December 1976issue of
Model Airplane News. The only difference
being that Prettner used an all balsa fuse­
lage while the Hobby Barn kit features a
molded fiberglass fuselage. For general in­
formation the Hobby Barn Curare specifi­
cations are as follows:
Wing Span-64 inches with a tuned pipe
Wing Area-695 sq. in. Hobby Barn offers the Curare kit in two
Airfoil-Symmetrical 16%thickness versions. One is a deluxe kit with all the
necessary balsa and a special hardware
(constant) package which sells for $96.99 (plus post­
Length (overall)-56 inches age). A basic kit is also offered which con­
Optimum Dry Weight (no fuel)-8.0 tains just the fiberglass fuselage and the
pounds
Wing Loading at Optimum
Weight-26.S oz.lsq. ft.
Engine Size--a strong .60 preferably
foam wing/stab cores, for a list price of.$59.99 (pages 32-33). Duke did an excellent job on sign considerations and flying hints.
(plus postage). For the purpose of this evalu­ this article which included a great many I could probably write pages of detailed
ation I chose the deluxe kit. This kit includes helpful photographs. I would suggest you comments on my new experiences handling
all the wing and stab balsa sheeting mate­ look it up or obtain a back issue before start­ both a fiberglass fuselage and foam wing!
rial; aileron stock; elevators; rudder; pre­ ing the installation. tail. A lot of it would involve my basic inex­
shaped %-inch plywood firewall; hardwood Hobby Barn supplies a special four page perience with this type construction. As such
blocks and wire struts should you decide to set of building instr-uctions specifically writ­ I will just highlight what I think were the
use a fixed landing gear system; wing hold ten around this Curare kit. A 14 x 22 inch most important points. Although the fuse­
down bolts and blocks; control surface reduced scale set of plans is included. Al­ lage is molded from epoxy resin I was sur­
hinges; control horns and the necessary ma­ though quite simplified, the plans contain all prised to find that the epoxy cements did not
terial for constructing the optional drag the necessary data. If you wanted a full size adhere very well. The fuselage was com­
flaps. The difference in price between the set of reference plans you could always pur­ pletely cleaned of mold release residue using
basic and deluxe kit is $37.00. The $37.00 chase them from Model Airplane News (Plan Acetone (per instructions). I learned later on
gets you all the extras described above. From Set No. 269). Also included is a one page when finishing the Curare that the Acetone
a purely value standpoint it is well worth re-print (or what looks like one) of Hanno didn't really do the job properly. In fact, at
getting the deluxe kit. But in all honesty if I Prettner's original article covering some de- the suggestion of Bob Pettit of Hohbypoxy
had to do it again I would have selected the
basic kit. Why? Well I'm very fussy when it
comes to balsa selection. The wood provided
is certainly good quality with even grain (not
a rejected piece in the lot). But it was a little
heavier than I would have personally
selected. The hardware provided is definitely
adequate, but not particularly my choice.
Over the years I have settled upon my own
favorite items of RIC accessory hardware.
Since I was going to use a retract system, all
the wire landing gear struts and mounting
hardware supplied with the deluxe kit was
unnecessary. So for those reasons I should
have selected the basic kit and bought the
balsa and hardware on my own. Since the
completion of my Curare I have learned that
Hobby Barn will be offering soon a Super
Curare kit for approximately $10.00 more in
price. I have no details on this new model hut
suspect tha t most of the comments made here
will apply to the Super Curare as well.
The fiberglass fuselage provided in the kit
is actually molded with epoxy resin. I prefer
this.q.ecause you can easily use epoxy cement
in the construction sequence. The fuselage
itself was about as perfect as you could ever
want. I can only hope it was truly represen­
tative of the usual kit quality and not spe­
cially selected because of this magazine re­
view. The exact weight of my fuselage, as
received, was 16 ounces, which is very light
(remember the fuselage is 56 inches in over­
all length). The front spinner ring area is Hereis the finished Curare ready to go on the line. Bob used an external radio antenna however now feels
sanded to an accurate pre-determined angle. that the extra time needed to install it inside the fuselage would be worth it.The design is just too clean to
This permits easy firewall installation re­ have an antenna hanging out in the slipstream. Bob greases in on a ten foot wide strip at Grumman'S RIC
gardless of your choice of engine and engine field(top lett).A low speed fly-by(top right). Bob poses with his new Hobby Barn Curare (opposite page).
mount. The instructions give a thorough de­ He liked his first encounter with fiberglass and foam. Note Kraft·single stick transmitter.
scription of this very critical firewall mount­
ing process. An interesting variation of this
scheme (authored by Duke Hoeckele) was
published in the May 1980 FLYINGMODELS
Curare
Paints, I washed the entire fuselage down cores. This particular glue seemed to really noticed, gave me no small amount of advice
with Hobbypoxy thinner. This eliminated soak into the raw foam. In come cases I had for this project), I learned that he was going
the painting problem I had encountered trouble with adhesion and had to resort to a toeliminate these naps on his next model. He
(which Iwill discuss later on). At any rate, suggestion by fellow FLYlNCMoDELSauthor, really didn't feel he used them that much.
when using either Hobbypoxy Formula 2 or Ron Farkas, whereby heat is applied with a More important, the flaps and the extra
G.M.P. six-minute epoxy, I found it neces­ Sealectric iron to the stubborn areas. This servo required to operate them, caused a 7
sary to reinforce every joint with small strips application of heat did help stick the balsa ounce weight penalty. With that in mind I
of fiberglass cloth (2 oz. variety). The epoxy .skins to the foam cores, but be careful that decided not to install the flaps. But, as you
cement, by itself, will crack and split away you don't apply too much heat and melt the can see in the photo, this caused a little dis­
easily without this cloth reinforcement. 80 cores.My biggest problem was that Istacked continuity in the fairing of the fuselage wing
be careful when mounting the firewall, wing up the entire sandwich of foam cores .and fillet as it meets the wing trailing edge.
hold down blocks, servo rails and the stabi­ balsa skins on top of my drawing board and That just about covers the Curare ki t high­
lizer. weighted everything down. Unfortunately lights. I will comment later on the weight
One thing the plans didn't call for was a the board was not exactly flat, with the result and balance aspects of my model as well as
platform to rest the fuel tank on. Ifyou didn't thata slight curvature developedat the wing the flying qualities. Probably the most dif­
do this your tank would fall directly on to the trailing edge. To correct this condition I had ficult aspect of assembling this model was
retractable nose gear assembly. I added a to fit my ailerons very carefully, adjusting the actual installation of the retractable
Ills-inch thick plywood floor, spaced just the hinge line as I went along. Afterwards I landing gear system since it must be fully
enough to allow the nose gear wheel to fully learned from Dave Brown that he stacks his integrated between the wing mounted mains
retract. For a fuel tank I was advised to go to foam core assemblies on a sheet of \4 inch and the fuselage mounted nose gear. This all
a I6-ounce capacity and specifically the Sul­ thick plate glass. Since you don't have to takes a lot of time and extra patience.
livan 8-16 slant tank. This tank sits flat push any pins into the build ing surface, plate
(angled front stopper pointing upward) di­ glass is an excellent choicefor a perfectly flat World Engines OS Max .61 FSR
rectlyon the plywood floor, supported on the surface. For the size and weight of the modern day
top and sides by scrap pieces offoam rubber. The plans did not call for any dihedral pattern competition model you need a motor
The plans call for A three-bolt wing mount braces or spars, which I felt was unaccept­ with plenty of power. The new OS Max .61
system (two at the leading edge and one at able. Prettner employed three plywood di­ FSR from World Engines, 8960 Rossash aa.,
the trailing edge).I added a secondbolt at the hedral braces in his original design. I decided Cincinnati, OH 45236, was recommended to
rear which, as you will see later, gave me a to add two Ills-inch plywood,full depth, di­ me by several local flyers who specialize only
goodattachment point for the back end ofthe hedral braces (actually they are more like in pattern competition. List price for this en­
tuned pipe. My choice of motor mount was spars) which run out just behind the retract gine is $159.95(including a muffler). Weight
the Kraft aluminum variety (Model-60R). landing gear mounts on each wing panel. of the engine is 17'h ounces. The OS muffler
This was still a little snug for the 08 Max .61 These braces are spaced in such a way to weighs an additional 41h ounces. As far as I
FSR and required some extra filing to make permit reinforcement of the landing gear can tell the two major differences with this
the engine fit properly. The larger Kraft 80 mounts (\4 inch plywood trays). I think it is new engine is the all metal precision car­
mount seemed just a little too big for this worth the extra effort to have complete piece buretor and the 5lJG-inchdiameter propshaft.
application. Although the original didn't use of mind while performing snap maneuvers. I won't give any tach readings here because
a spinner this kit version does. Quite frankly The biggest problem I faced with the wing I'm going to leave the detailed engine per­
the design looks a lot better with a spinner. I construction was the cut-outs for the retract formance evaluation to our new resident en­
selected a C.B. Associates 2-inch diameter system. The plans give you a gear strut loca­ gine expert, Mr. Mike BiUinion of Great
aluminum spinner which is made well and is tion but don't really tell you the distance Britain. I hope Mike has this engine sched­
relatively inexpensive. between the bottom surface of the wing skin uled for an upcoming review. My comments
Both the wing and stab foam cores pro­ and the center of the wheel axle <thedistance presented here will be more of a personal
vided with the kit were of excellent quality in my case turned out to be 3%inches). With­ testimonial.
(good average density and very smoothly out this dimension I was forced to mount the After all the effort of building the Curare
cut). Ifyou read any of my design articles in main landing gear assemblies first and (admittedly with techniques new to me) and
FLYINCMODELS you know I'm not a foam worry about the wheel well cut-outs later on. installing the retracts (also new to me) the
wing man (but I may be before much longer). Hobby Barn also provided the material one item I paid least attention to was the
I used Carl Goldberg's Blue Goo contact ce­ and details for the inclusion of two small engine. On the day of the first flight I did
ment to adhere the balsa sheeting to the drag flaps (located just outboard of the fuse­ something I never did before. I brought out
cores. In my case 7 ofthe 8 ounces (froma full lage at the wing trailing edge).Again, In talk­ my new plane, got all the camera equipment
can) was used to cover the wing and stab ing with Dave Brown (who,as you may have set up to record the first flight-and I had

Hereare the contentsof the HobbyBarnDeluxeCurarekit whichlistsfor Thefoamwingand stab cores havealreadybeenskinnedand are displayed
the necessarybalsa sheetingand hardwareis supplied.
$96.99. All in the background.The remainingbalsa.hardwoodand parts in tront.

2016
Curare
never run the engine before. The OS in­
structions say you only need to run a single
tank of fuel through this engine before fly­
ing. That's what I did-at the field. The OS
Max .61 FSR started on the second flip of the
prop, right out of the box. I set the engine at
full throttle and opened up the needle valve
for a very rich four cycle run. Every couple of
minutes I leaned it out for a few seconds and
then returned it to a rich four cycle.I contin­
ued to do this until the 16 ounce tank was
drained. After a quick fill-up I made the first
flight. The engine held its needle valve set­
ting for over a 10 minute flight and the idle
was about as low as you could go without
stopping. r might add that it idled that way
with the factory carburetor setting. I have
not had to make any idle adjustments at all.
For my initial flying I used a Zinger 11-7
wide blade prop.' A consensus of opinion
(from the experts) seems to indicate that an
11-7'h prop would be the better choice.I have
yet to find this out. I do take the trouble to
balance all ofmy props. Sometimes I.still end
up with vibration problems despite all my
good intentions. In this case the enginel
aircraft combination did not produce any
noticeable vibration at any speed level. Even
though the OS Max .61 is physically a large
engine, 1had no problems mounting it to the
Kraft radial mount. A long DuBro allen
wrench does the job easily. As you will find
out in the next section, I did use a tuned pipe.
For my first flights I thought I would try the
regular OS supplied muffler to simplify
things. Unfortunately this muffler does not
lend itself to easy mounting with the cylin­
der head on its side. It would have required
cutting a lot of the nose section away to clear
the muffler. Had I planned ahead and
mounted the engine cylinder at a slight up­
ward angle, I could have mounted both the
muffler and the pipe header easily later on.
So keep this point in mind when you mount
the engine in the Curare.
The bottom line on this engine is that it
performed great! It has plenty of power and
best of all it is extremely reliable. Consider­
ing the final weight of my Curare I wouldn't Bob is shown here using a Custom Crafts Mitre Sander to obtain the correct dihedral angle at the wing
like to think about a dead stick landing, root. A photographic print roller was used to insure complete contact of tn"esheeting to the cores (top).
especially with the small size of my local Note the use of weights to hold down the stack of balsa and foam while the cement dries firm. Be sure the
flying field. Howmuch did my Curare weigh? wings are weighted down against a perfectly flat surface. A bottom view of the joined wing panels
Youhave to keep reading, I won't ownup to it (below). Note the two full depth '/,6" plywood spars. Landing gear mounts connect to the spars.
until later.
MAC's Tuned Pipe
To get the very best performance out of
your pattern competition model the experts
say you need a tuned pipe exhaust system on
your engine. There are many types of pipes
manufactured for use with model engines. I
chose Mac's Products for this application be­
cause I use their mufflers and tunable
exhaust extractors on most of my other en­
gines. Wally McAllister of Mac's Products,
8020 18th Ave., Sacramento, CA 95826,
supplied me with one of their muffied tuned
pipes (Model 10 MP, which lists for $25.95).
The keyword is "muffled". Alsoavailable is a
pure or straight pipe (no internal baffles)
designated as their Model 10TP (list price of
$19.95). I suspect the 10TP pipe might give
higher r.p.m.'s, but would cause a much
higher noise level. The 10 MP pipe is 19 inch-
Curare
es long and weighs 6 ounces. You must also
purchase a header pipe to be able to attach
the muffled pipe to your engine. For my ap­
plication Wally provided me with one of his
Model 1621 HP header pipes in the extra
long configuration Gist price $16.95). The
extra long model is intended for side mount­
ed engines where the pipe is run under
the wing. Included with the header is a short
length of silicone tubing which provides a
flexible connection between the header and
the pipe. Also provided are two nylon cinch
straps which help hold the silicone tubing in
place.Unfortunately no provision is made for
attaching the pipe on the other end. Most of
the articles on tuned pipes that I have read
fell flat on their face when they got to the
part concerning pipe attachment to the
model. The method I used is a slight varia­
tion ofthe scheme used by Dave Brown.Dave
described this to me in a phone conversation.
I hope I understood him correctly. I replaced
one of the two nylon rear wing hold down
bolts with a 3-inch long,10-32 steel bolt.
Since the steel bolt would easily pull out of
the hardwood hold down block I added a
10-32"T" nut (inside the fuselage). The idea
here is to use two nuts and twolarge "fender"
washers. The bolt first is threaded into the
"T" nut. One nut is tightened down against
the wing, holding it in position. About 2
inches of the bolt projects beyond the bottom
of the wing surface. At the end of the bolt a
second nut is tightened up against a "Mil
type" (rubber covered) large cable clamp.
Tightening this nut against the head of the
bolt will exert enough pressure to hold the
rear end of the tuned pipe firmly in place.
Admittedly the back end ofthe pipe has to be
disconnected every time you remove the
wing, which is somewhat of a nuisance. The
alternative is to mount the engine upright,
which allows you to permanently attach the
pipe to the side of the fuselage. Experts tell
me that these pattern models fly better with
the pipe mounted under the wing. One bene­
fit of the under wing pipe mounting is that
the model is a little better protected should a
"wheels up" landing becomenecessary. Total
weight of the pipe and header is close to 8
ounces (6ounces for the pipe and 2 ounces for
the header). This weight is about evenly dis­
tributed fore and aft of the C.G. I tried the
pipe at full length for my first flights since it
is always better ito have the pipe too long
than too short. To tune the pipe you must cut
off the header pipe v.. inch at a time until an
increase in r.p.m. is noted on a tachometer.
After that take off I;ij inch at a time until no
further increase in r.p.m. is noted. Under no
circumstances should you attempt to cut off
any portion of the pipe itself. No mention is
made ofa pressure tap. I decidedto make my
tap at the header, not the pipe. I installed a
Fox 6-32 pressure tap on the header, imme­
diately after the exhaust port (pointing to the
glowplug). Use a goodsilicone fuel tubing so
it won't melt on you. From both a quality and
cost standpoint the MAC'sProducts pipe and
header looks like the right way to go.
Sonic Systems Turfmaster Retracts
There is still a big debate with pattern
flyers as to which retract conceptis the best.
Curare
You have a choice between a full air system, Next the strut itself is raised or lowered.And This hook up permits the nose gear to be
a full electric system or a pure mechanical finally the lock is reset. To help in the timing steered off the rudder servo only when the
device operated directly by a servo.Each has of this sequence it is recommended that you gear is extended.
its advantages and disadvantages. Sonic use a 180 degree retract servo. These servos You will end up with a lot of "plumbing"
Systems, P.O. Box 192, Whippany, NJ generally take about 3 seconds for full rota­ (plastic tubing) being routed all around your
07981, had just introduced their new tion. You could use a 90 degree (standard) model. SonicSystems supplies red tubing for
"Turfrnaster' retract system last fall when I servo, but the linkage adjustment to the con­ the retract function and black tubing for the
started acquiring the material for this arti­ trol valve would be very critical and there­ lockingcylinder function. Four lines must go
cle. The unique feature of this new system fore Sonic Systems does not recommend it. to each gear unit. Then additional lines must
was the inclusion of a second cylinder (on On my Kraft Signature transmitter I can set gofrom the storage tank to the regulator and
each gear unit) expressly for locking pur­ a regular 90 degree servo to operate up to then on to the control valve. The storage tank
poses. This means that all three gears are about 160 degrees rotation. But the problem was cemented into the top of the fuselage (in
positively locked in either the extended or I found was that the rotation speed of the the area of the wing trailing edge) using
retracted positions. I decided to try their standard servo was a little too fast. A slow silicone rubber bathtub caulk. A disconnect
trike gear set which is designed as Model800 180 degree rotation servo is definitely the point is required between the wing and the
and listsfor $119.95. Before getting into the best choice. . fuselage. To make this chore easier, Bell
details' of this system I must honestly say Sonic Systems also supplies a pressure Wardlow ofSonic Systems, supplied me with
that this is not for the beginners. This system regulator which can be adjusted to prevent two sets of his "Quick Disconnects" (catalog
is basically simple and straightforward in the gears from retracting too fast and liter­ No. 309). Each set consists of two mating
theory, but it does take a great deal of plan­ ally slamming into position. This works fine pairs and lists for $3.95. Two complete sets
ning and time to get it all packaged into your but there is a limit as to how slowyou set the are required for the Turfmaster system. You
model. The instruction booklet provided is retract speed. If too slow the system might must also identify these interconnecting
very detailed in every respect. However, it attempt to re-lock before the gear finished lines otherwise it is possible to have the
still took me many readings to fully under­ cycling. So don't look for a real scale retract gears work out of the proper sequence.
stand the installation and operational as­ operation as is obtained on the electric sys­ Another interesting point! This system is
pects of this system. The very best piece of tems. not fail safe. If you should loseair (because of
advice that I received came from modeling I might add that you should definitely use a leak) or run out of air (carelessness) you
friend, Joe Redan, was to first set up the air (from a pump) to operate this system. Do won't be able to unlock the gear struts. In
entire retract system on a bench in a not attempt to use Freon at all. SonicSystems other words you would not be able to release
mock-up type set up. Install all the tubing sells a pump specifically designed for this the gears and let them drop into place.
and get everything to operate properly before purpose which will easily fit in your Although possibly a little more compli­
attempting installation in the model. Once model field kit. It is called the Sonic Super cated than other retract systems, the
working on the bench all the plumbing can Charger II and lists for $12.95. About 25 Turfmaster system does work reliably. How­
be identified with tape or cable markers, pumps is necessary to achieve 100 p.s.i. of ever, there still is an inherent problem with
which will permit easy re-assembly in the pressure in the airborne storage tank. That all the retract systems now on the market.
model later on. should be enough pressure to cyclethe gears Even with the most reliable mechanism your
Each of the three gear units (two mains several times before re-charge is necessary. wheels can still get stuck up in the wells due
and the nose gear) has two pneumatically Total airborne weight of the trike gear sys­ to the wire bending rearward in rough grass
operated cylinders. One cylinder extends or tem is 13.5 ounces (less the wheels, of takeoffs rendering the system useless, This
retracts the landing gear strut. The other course). Sonic Systems supplies the struts is because the wheels then snap into the
locks the strut at either of the two extreme (5/32 inch diameter) without the axle bends. wells but will not comeback down.To correct
positions (wheels up or wheels down). The You can either bend the strut yourself or '(as this problem many modelers have resorted to
heart of the system is a master control valve. suggested) use the Carl Goldberg axles extremely small wheels in combination with
This valve simultaneously controls the air which are very easy to install and adjust. I very generous size wheel wells. My particu­
going to the retract and locking cylinders. decidedon the latter and it workedfine. Both lar flying field would certainly not tolerate
You must precisely connect up a servo to the main gear units and the nose gear mech­ wheels much smaller than 2Y4-inchdiameter
operate this valve. Linkage connections, to anism have the same mounting hole dimen­ mains and 2 inch diameter nose, as I used on
the valve, are extremely critical requiring a sions as the Rhom-air systems. Mounting my Curare. An alternative would be to slope
great deal of care during installation. In wise they are completely interchangeable. the sides of the wheel well, thereby eliminat­
normal operation as you hit the retract The nose gear unit is mounted in a vertical ing the chance of the wheels binding. This
switch on your transmitter the servo will position on the lower rear portion of the would, however, make for more drag since
begin to rotate. First in the sequencing the firewall. Connection to the sliding nylon the well openings would be considerably
lock mechanism is withdrawn, permitting nose gear steering arm proved a lot simpler larger than we are presently using. The ul­
free movement of the landing gear strut. than it initially looked in the instructions. timate solution is going to be articulated

Thisis one of the mainretractunits.Bobchose the SonicSystemsset. The close-upofthe nosewheelwell.showsthe connectionto the steeringarm.
A
gear is showninthe extendedposition.Notehowthe fourair lineshaveto The support for the steeringcable must be accuratelylocated so that it
pass beneath the wheelwellopening.Bobfuel-proofedthe wells. doesn't interfereduringthe retractionsequence. A tight fit.
Curare
landing gear doors or covers as employed on
full size aircraft. It may sound complicated
but it might be worth it if you didn't always
have to worry about wheels up landings.
Finishing
Again just the highlights. I applied %
ounce fiberglass cloth to the wing using a
thinned mixture of white glue. This tech­
nique has been used on Long Island with
certain success. It does a job, not as good as
polyester resin, but at least it doesn't smell
up the entire house. I applied two brushed
coatsofHobbypoxy grey primer undercoater,
wet sanding between coats. This was fol­
lowedby a brushed coat of Hobbypoxyyellow
and then two sprayed coats of yellow
(thinned considerably). Again I wet sanded
between each of the coats. The black trim
paint was added next. I used 3M brand
'Is-inchthick automotive trim tape (silver) to
separate the paint colors (black fromyellow).
This tape is a lot cheaper than the variety
offered for the hobby market. After applying
all the decals I gave the entire model a light
spray coat of Hobbypoxy clear. This all re­
sults in a gooddurable finish. But remember
my caution at the beginning of this article­
clean the raw fiberglass fuselage with Hob­
bypoxy thinner, not acetone as stated in the
instructions. Failure to do this will cause
problems with epoxy cement adhesion and
will also cause a paint problem which t.he
experts call "fish eyeing".
Radio system and installation
The radio installation included a Kraft
KPR-7F receiver (operating on six meter
FM). Because of the large fuel tank, the re­
ceiver and a Kraft KB-4E 550 MAH battery
pack were installed in the RICcompartment
just behind the wing leading edge. The re­
mainder of the RIC compartment was taken
up by four Kraft KPS-15 servos. The two
forward servos handled the rudder and throt­
tle functions, while the two aft servos operate
the elevator and retract system air valve. A
single new Kra£t KPS-20H servo was
mounted in the wing for the aileron function .
Hardwood servo bearers were used through­
out. No servo trays were employed.
FOl"a model of this size and weight you
must be very careful with your control sur­
face installation. I used five DuBro hinges on
each aileron, three on each elevator and four
on the rudder. Elevator and rudder surfaces
were activated via Sullivan fiberglass rods
(stock No. 509). Because of the anhedral in
the stabilizer you will have to provide a split
or "Y" yoke connection at the rear of the
fuselage (each elevator half is essentially
separate). DuBro ball and socket sets work
well in this application.
I did run my radio antenna on the outside
of the fuselage up to the vertical fin. In ret­
rospect I'm sorry I didn't take the time to run
an outer Gold N' Rod up the inside of the
fuselage towards the tail and then insert the
ant.enna inside this tube. For a model as
clean as this an internal antenna is the right
way to go.
All of the radio equipment described here
(with the exception of the KPS-20H servo)
were previously reviewed in FLYlNG MODELS.
Curare
You may want to refer to the following is­ even. Dave's wing complete with naps, two moved the 4 ounces of lead ballast. I'm now
sues: Kraft Signature transmitter- April servos and the retracts, run 2 pounds 12 nying at 8% pounds(the difference between
1978;Kraft FM receiver-FM module and ex­ ounces. My wing, without flaps, came out to 3 that and 9 pounds is unnoticeable}.
ponential rate control- December 1979 and pounds even. What can I attribute this over­
finally the new KPS-20H servo- July 1980. weight condition to? I believe it wasbasically Final comments
Back issues of all these FLYING MODELS are the selection of the balsa sheeting that added By the standards of expert pattern flyers
available from the Carstens Publication of­ a part of this. The wood could have been a my particular Curare is definitely a bit
fices in Newton, New Jersey. lighter weight grade. The 7 ounces of Carl heavy. However, it still does perform wei!. I
The basic radio system described here has Goldberg Blue Goo contact cement used to might also add that it is very easy to fly. A
been in operation for about 1%years in sev­ adhere all the sheeting to the foam seems reasonably average Sunday sport flyer could
eral other models. It has performed perfectly excessive (or at least now it doesl).Probably easily take on the likes of the Curare. I do
except for an intermittent switch harness the slight tail heaviness noted can also be expect to fly this particular model in compe­
which I fortunately detected before it caused explained by the heavy balsa stabilizer tition during the 1980 season. I definitely
any problem. I am using exponential rate sheeting. I noticed on a similar pattern learned a lot during the construction of this
control on both elevator and aileron (all the model the designer called for a built up rud­ model. Surprisingly I spent several months
time). Quite honestly I would like to have der in the interest of saving weight in the constructing this Curare. The next one
this feature on the rudder function as well tail. The original Curare design had an indi­ would probably only take me half that much
since it would really smooth out the take off cated C.G. of 31.8 percent of the M.A.C. time. I'm sure I could easily trim a halfpound
run and landing rollout. And finally the new Hobby Barn Curare plans calls for a little offthe next one which would greatly improve
heavy duty Kraft KPS-20H servo is every bit more conservative C.G. location of 27.2 per­ its performance during some of the vertical
as fast and precise as it looked during my cent of the MAC. Although the main land­ climbing maneuvers.
bench testing. I will probably now replace ing gear units were accurately located per The one thing that really surprised me was
the remaining .KPS-15's with the 20H's in the plans, I did find that the Curare would the lack of real detailed information on pat­
the next few months. For information, the almost rest on the tail skid (without any fuel tern models. I did a substantial magazine
airborne weight of my RIC equipment in­ in the tank). This kind of upset me a little so I search before starting this project. This
stalled in the Curare, is 16 ounces. That in­ choseon the first flight to add 4ounces of'lead search indicated that a good deal of the de­
cludes all five servos and the 550 MAH bat­ up in the nose, which brought the total flying tailed information is still left up to trial and
tery pack. weight to an even 9 pounds (dry). error. This all tends to keep pattern flying as
To my surprise, on the first flight, the somewhat of a "closed fraternity". It
Weight, balance and flying Curare took off in less than 100 feet. The shouldn't be that way and, in fact, sport
Here it comes my friends! My Curare climb out was incredibly fast for a 9 pound flyers should be encouraged tojoin the ranks.
topped offat 8%pounds total weight less fuel model. Remember also, I had not even at­ Was it all worth it for me to try flying
and it appeared slightly tail heavy. I can just tempted to tune the pipe at that point. On the pattern again? Well, quite honestly, you
see the experts laughing already. My only first flight I tried a few stalls and found them haven't really flown RIC until you have pi­
defense for this high weight is inexperience surprisingly gentle with plenty ofwarning. I loted an 8 to 9 pound model, flying at close to
with this particular type model. In talking made a few very slow speed fly-bys for pho­ 100 m.p.h. If you are presently a good sport
with Dave Brown I learned that his Curare tography purposes and felt 1had perfect con­ flyer, take the next challenge. It's a bit more
type models are coming out around 8 pounds trol at all times. After that first flight I re- expensive, but very rewarding! G::
and I like to believe are among the best you
can use.
After you order your wing and stab compo­
nents, visit your local hobby shop and pick up
the rest of your supplies. Take care in your
wood selection, as you want the lightest and
straightest there is. We're shooting for an
all-up flying weight of around 55 oz., so light
building is paramount. Once you have all
your supplies, the fun begins. The following
construction hints may help in cutting down
your building time and effort, which will get
you into the air as quickly as possible.

Fuselage
Since the wing and stab are almost ready
to go into the fuse, we'll build it first. Begin
by cutting two sides out of 48"sheet, two ply
doublers, the two forward bulkheads and
your motor mounts. AUthe woodsizes can be
found on the plans. Laminate the ply dou­
blers, using 15minute epoxy,to the fusesides
being sure to make a left and a right.
Using 5 minute epoxy, glue the motor Thecleanlacetrimpanelsare evidentinthisphoto.Stuntersare knownfortheirpaintand inklinework.
mounts to each side. When these are set up, John appears to be happywithhis new ship (opposite page top).A front·viewshows the dramatic
carefully align the bulkheads, using a anhedralstab (oppositepage bottom). A plus is the adjustableexternalcontrol linkage.
square, and epoxythese between the two fuse
sides. Pull the rear of the sides together and
epoxy.
Install the engine, bolts and blind nuts,
plywoodspinner ring and spinner. Check for
a degree or two of engine offset to the right quality of these items, this is the time to put We now have the three basic components
side. Tack glue the top block and bottom them to use. needed to finish the model.
sheeting in place along with the engine cowl. Make up your control systems using a 3"
Now, we have something that looks like a bellcrank. Epoxy the bellcrank bolt to the Final assembly
4-foot 2.,,4. left wing panel vertical plywoodspar. Cut a Cut out the wing openings in the fuselage,
Get out the #80 grit sandpaper and your notch in the right panel for the flap pushrod, being careful to keep things accurate. Cut
razor plane, and get at it. Once you have the and use 5 minute epoxy to join the wing the bottom part of the fuselage under the
basic shape, graduate to about #320 paper halves, using the bottom foam cradles to help wing away and test fit the wing to the fuse.
and finish sand. in alignment. Be neat! When you have gotten it absolutely straight,
Cut the rudder and vertical fin to fit to Using scissors, cut a couple of 1%" strips of glue it in permanently with 5 minute epoxy,
fuse. Now trim the canopy, and fit it to the 1/32" ply. Epoxy these over the wing center install the bottom ofthe fuselage, and let dry.
fuse top block.Do not glue it yet. Removethe section front to rear, top and bottom. This Install the stab and elevators in the same
canopy, topblock, bottom sheeting and cowl. provides a stress platform and makes the way, with hinge Jines parallel and vertical
Hollowall these until a lOO-wattlight bulb is wing virtually one piece. measurements accurate. Make up the el­
dimly visible when held up to it from the Tack-glue the wing tip blocks and carve evator pushrod using 3/32" piano wire, and
other side. You want a light plane, right? them to shape. Now remove them hollow out. two 440 heavy duty qwik links. Keep the
Right! Install a Control Specialties lead-out guide bends in the pushrod at the back as
Make all your cowl openings and hold in the left tip, and a tip weight box in the minimum as possible.
down attachments. Bend the tail wheel wire right tip. Permanently epoxy the wing tips Hook up the pushrod to the flaps and el­
and install, using copper wire and plywood. on, and finish sand to shape. evators and check for smoothness. The flap­
You now have a fuselage that is basically­ Join the flaps with a 5" horn, check the fit to-elevator ratio should be approximately
complete except for the canopy and cockpit atwing tips, and install the hinges and flaps. 30°to 45°,or 2 to 3. Install a pushrod guide in
detail. Finish sand the vertical stab and rud­ Hook up each flap pushrod for maximum the fuse to eliminate pushrod flexing. Using
der and set them aside with the fuse. throw on the bellcrank and minimum move­ a toothpick, put a drop of STP on all the
ment on the flaps. Check for neutral setting on control joints.
Wing and stab the beJlcrank and flaps, and freedom of Permanently glue on the bottom sheeting
Since by now you have received the wing movement. and hollowed out double blocks, using Aero
and stab and have looked in awe at the Install the landing gear blocks, using 5 Gloss or Tester's cement. This keeps the
minute epoxy. For strength, cover the block seams from showing later on.
area 2" outside the gear blocks with light­ Cut and shape flap and elevator fillets out
weight fiberglass cloth and resin. Sand the ofscrap balsa and install, being careful not to
completed wing and flap with 380 grit, and get any glue on the control horns.
set aside. Check the airplane over at this stage for
The stabilizer and elevators are built in accuracy and alignment, and, if satisfied, in­
much the same way, with the exceptionofthe stall cockpit detail, canopy and rudder. You
anhedral in the stab. Cut and join the stab nowhave the basic airframe ofyour My Blue
halves with the anhedral as per the plans. completed,.ready for fillets.
Install the balsawood tips on the stab and At this point, install all the hardware, i.e.,
elevators, and sand to shape. Look carefully landing gear, wheels, engine, tank, etc., to
at the pictures and plans to see how the el­ check for weight. The model should weigh no
evator horns are installed. Each elevator has more than 45 to 46 oz. at this stage.
a separate horn, so you will need two horns.
Fit the horns to the elevators so that the Finish
vertical part with the holes is clear of each The original My Blue was finished with
side of the fuselage. Again, refer to the pic­ nitrate dope, with a coat ofclear acrylic. The
tures. clear acrylic does not shrink, therefore, if you
Cover each control horn with fiberglass have smooth fillets to start with, they'll stay
and resin for strength, and hinge the stab to that way. This also results in a very glossy
the elevators. finish, with no rubbing involved. The se-
 John prefers to use a plastic fuel tank. The vents are of uniflowtype. AnST.46 The massive nose makes for a solid engine mount. It's a must for a smooth
provides the power. Note the neat compact muffler. The adjustments for the running motor. John gives us a look at the profile (top). A Wing Mfg.Racing
elevator linkage and movable rudder can be seen here (below). Canopy is used to good effect here (below}.Details garner points.

quence is as follows: is the time to fix them. Spray on one more Set the lead-outs as per the plans, and use
Install the wing and stab fillets, using coat of silver, and lightly sand to a dull silver approximately % of an ounce of wing tip
Epox-O-Lite and water. Use the water to get finish. weight for initial flights. I use 62' lines and a
the final shape as near as possible as this The model is now ready for the base color Baron adjustable handle, which seems to be
saves a great deal of sanding. Brush on two coat which, on the original, was a light the optimum setup.
coats of nitrate clear, and sand after the sec-. metallic-blue. Check out engine and controls on the first
ond coat. Spray on a light coat of color, just enough flight, and make minor adjustments if'neces­
Using 00 silk span, paper the entire air­ to cover. Let dry overnight before masking sary. Now, go ahead and take her through a
plane using 500/0 clear and 50% thinner. for trim. The trim on the original was done in pattern.
When dry, brush on another full strength white panels with blue lace overlay, and You'll find that you have a responsive and
coat of clear, and sand. Check for any rough air-brushed border of darker blue. groovy model that is totally at your com­
spots at this time, and fill any dents or dings From here on,let your imagination be your mand. However, if it doesn't really feel this
also. guide. Ink lines and rub-ons add much to the way, add nose and/or tip weight to suit.
Mix up some clear and talcum powder and character of a model and, I feel, should be Put in as many practice flights as possible
brush on entire model. Sand as much off as used but not overdone. and, with some concentration on your part,
possible, being careful not to go through to Spray the entire model with clear and let there will be no red ribbons for My Blue.
the paper. Check in the light for smoothness, dry overnight, being careful not to get any Editor's note: John Poynter is not only (1
and brush on more sealer over any rough runs. fine stunt /lyer, designer and author, he is
spots. The model should now have a dull Flying day is here! Install the motor, tank, also apurveyor of fine {oam wings. The toings
matte finish with no grain visible. wheels, and double-check everything. If pos­ and stab for My Blue are available from him
. Break out your air compressor and spray sible, run the engine once or twice before at J&K Foam Wings, 10261 Janice Lane,
the entire model silver. The silver will show flying so that it won't quit just when you need Cypress, CA 90630 or call John at 2131596-
any bad spots you may have missed, and now it. 9053. ~

September 2016