and article for the Curtiss JN-4D Jenny biplane, by Dick Hansen, were scanned from my purchased
copy of the September 1968 American Aircraft Modeler magazine (page 18). Plans for this fine model
were drawn by Dick Hansen. All copyrights (if any) are hereby acknowledged.
"The Curtiss JN-4 Jenny two-seat biplane was one of the most popular planes of all time. Although
the JN-4 series of aircraft was technologically unremarkable, it was significant in that it was
the first mass produced plane and was manufactured in larger numbers than any other American plane
up to that time. The Jenny never saw military action but met the need for a dependable military
trainer. From April 1917 when the United States entered World War I, it was used to train some 95
per cent of all U.S. and Canadian pilots.
whole generation of Americans learned to fly on Jennys, and in addition to U.S. and Canadian pilots,
flying schools in Great Britain and France used them as trainers. After the war, thousands were
sold to civilians, and the plane had a second career as a barnstorming plane, thrilling spectators
at traveling aerial pageants and shows throughout the United States. By the Armistice in 1918, more
than 6,000 JN-4s had been built, including some 2,700 JN-4Ds, the most widely produced version.
Airplanes and Rockets visitor Thierry L., of Belgium, wrote to ask for a larger version of the
plans image file so that he could scale it for building a 40" wingspan version for electric power.
He was kind enough to send a photograph of the framed-up Jenny. Doesn't that look nice? It is always
a shame to have to cover such fine handiwork, but the finished model will undoubtedly look just
"I'll try to create a "mechanical sound generator" to produce a low rpm noise because original
engine turns very slow in comparison with electric motor," writes Thierry.
Curtiss JN-4D Jenny
Built by the thousands during WW I, this gawky, lumbering trainer became king of the postwar barnstormers.
The model captures the in-flight realism of by-gone days.
Although not a super-scaler, the Jenny has won a few scale contests because
of its great realism. In flight, it is as stable and stuntable as a real Bisso Jenny.
TO the fledgling birdmen of WW I, the Jenny was what the AT-6 became to thousands of WW II pilots.
Designed and built by Glenn Curtiss, it was originally intended as a trainer for the Glenn Curtiss
With the outbreak of WW I, the Jenny was ordered in large numbers by the U. S. Army as well as
Great Britain, France and Canada. Of the 7,000 JN-4's built, over 3,000 were the "D" model. With
a wingspan of 43' 7-3/8" and length of 27' 4" she was big and cumbersome. Power was an OX-5, V-8
90-hp engine which yielded top speed of 80 mph. Stalling speed was around 45 mph. Later versions
were equipped with the 150-hp Hisso engine which upped performance considerably.
So many were left after the war that the Jenny was greatly favored by the barnstorming and stunt
pilots. Cost was just a fraction of what the government had paid, and some came new in the crate.
They were still sold as surplus as late as 1927. Just about any airshow that was worth seeing during
the 1920's, and up into the late 1930's, had at least one Jenny performing. The last time I saw
a pure Jenny perform at an airshow was 1947. She was the star of the show, in my estimation.
Introduction: You will be surprised how much easier a large airplane is to fly and handle on rough
ground. The swing in our club is to the larger airplane as we find it more realistic in the air
and on the ground. Nothing gathers crowds at the local flying field like a large aircraft, especially
a scale job, with two wings - what will they think of next!
Forward fuselage side panels are made of soft, thin aluminum, shaped and burnished by hand."
They are screwed in place over the balsa sides. Dummy engine heads servo as cooling outlets
for the hard-working Enya 60 engine.
The Jenny is a fun airplane, not a super-detailed ship to win contests with. Although she does
have two trophies to date, it is not hard to build and, in fact, was one of the easiest in a long
list of craft including an 8-foot Aeronca Champion, 6-foot Kingcobra, two Astro Hogs, etc. Flying
characteristics were better than anticipated. Wind penetration is good. She turns well on ailerons
and flies a little faster than expected, probably due to the thin leading edge. Having a simple
flat bottom airfoil creates much lift at slow airspeeds and much more lift at higher airspeeds.
It should be flown with this in mind.
One drawback of large aircraft is the assembly and disassembly time at the field. This is why
the wings are of one-piece construction and the only functional flying wires are included.
Most early biplanes were noted for their short nose-moment arms. Not so the Jenny. However, construction
should be on the heavy side in the forward section as I had to add a slight amount of dead weight
in the nose to balance properly. Do not worry too much about weight, except in the tail as this
plane could weigh three pounds more and still fly well. Do make sure there is ample cooling for
the engine. It is easy to burn one up, as I did in my Aeronca Champ for lack of adequate venting.
Changes made in the plans over the original model are: straight bottom hatch, aileron horns on
bottom of aileron, nylon screw for landing gear and lower wing hold-down, although Dzus fastener
or camlock can be used. Also the use of a round 8-oz. tank rather than an oval one.
The model has been flying for over a year with only one mishap. That was an engine backfire in
the air that resulted in a lost prop nut and washer. She is powered by an Enya 60 and guided by
a Kraft KP-6 proportional rig. If you are worried about the metal-to-metal connections causing interference
in your receiver, you had best re-engineer these for noiseless operation.
Left: Enya 60 installation offers lots of cooling for the engine, a large
oval-shaped fuel tank and break-away motor mounting. Note aileron plug and leads beside left, front
cabane strut. Center: Wood finish on panel and Tatone instruments. There were not many gauges
on real Jenny's either! Right: With six feet of wing span, the struts are functional.
Fuselage: Construct entire aircraft with Titebond glue except where noted. Cut fuselage sides
from 1/8 sheet and splice where shown. Use 1/16 plywood doubler forward and 1/32 plywood doubler
at the tail. Use contact cement for these. Cut out all formers. Bend cabane struts from 1/8 wire
and fit to formers F-4 and F-5 with straps of galvanized sheet metal before these formers are glued
in place. Join halves together at tail and glue all fuselage formers in place. Glue in hardwood
engine bearers, forward landing gear mounting block, with blind nuts installed, and top and bottom
of battery compartment. Fit lower nose block. Glue the hatch rails together and let dry before pinning
to fuselage for hatch construction. Glue in servo mounting. Board under formers F-10 and F-11. Use
1" sq. balsa for nose ring and 1/8 aluminum plate for engine mount.
After hatch rails are dry, pin to fuselage and glue formers in place. Plank hatch with 3/23 x
3/8 balsa strips. Cut cooling holes in each side of hatch, scallop out former H-2 and build air
ducts from scrap balsa through each hole. To hide these outlets, I used fake rocker box covers open
at the rear; however, you may have better ideas closer to scale. Construct a metal exhaust extension
for the engine or build an exhaust duct into the hatch. Hatch is held in place with a single bolt
through top of hatch to nut soldered to a loop of 1/16 wire screwed to engine bearers.
The nose side panels are made from very thin aluminum roof flashing. Drill 1/16 holes where indicated
and cut slot between them. Place panel on a flat soft surface and push slots out about 1/8 to 3/16
with the sanded end of a 1/8 x 3/4 stick. Screw panels to side with smallest wood screws available
noting that two open screw eyes forward are used for attaching flying wires from upper and lower
<click for larger version>
Bend landing gear from 5/32 wire and shock loops from 3/32 wire which are silver soldered
to main gear. Make axle from 5/32 wire using 5/32 I.D. brass tubing for extension. Drill small hole
in each extension to receive cotter pin keeper. Secure axle by wrapping rubber bands around it and
extended point of loop for shock absorption. Rear landing gear struts are attached to 1/8 plywood
plate with metal straps and the whole assembly pivots on the forward gear mount.
Cut two 8-3/16" lengths of 1/8 wire and wrap and solder to top of cabane struts then sew and glue
a 1/8 sheet of plywood between them for a wing mount. Cut out cockpit openings after planking top
of fuselage with 3/32 x 3/8 strips. Use automobile windshield wiper hose for coaming. Windshields
are cut from heavy acetate plastic.
Author explains that wing tip skids are as important on model as on real Jenny. On grass, all
ground handling is easy with the effective, steerable tail skid. However, it takes practice
on hard surfaces. Tip skids prevent wearing out wing tips!
Make aileron servo connector hole near one of the forward cabane struts and secure connection
by taping to cabane strut while flying. Glue 3/16" sq. stringers in place and hardwood braces at
lower wing opening. Glue 1/8 plywood tailskid mount in place before sheeting bottom with 1/8 balsa.
Make tailskid from 3/32 wire and brass eyelets and install before gluing stabilizer in place. Solder
1/32 wire bellcrank to tailskid for steering spring to hook on. Drill and install 1/16 O.D. brass
tubing at bottom of tail for tail bracing wire to pass through.
Sand well and cover with silk.
Wing construction, upper: Cut all ribs from 3/32 balsa sheet, except for those indicated as plywood.
The 6-foot aluminum spar is available from most building supply stores. You can substitute a thicker
wood spar if you like, but it will not flex as well nor be as strong as the metal spar. Cut three
inches from the end of the spar for use as dihedral brace. Hacksaw two-thirds of the way down in
the center of the spar and bend up so there will be 5/8 under each wing tip. Rough up center area
of spar so that epoxy glue will hold well. Extend metal spar to tips with 1/16 hardwood. Bevel 1/2"
sq. leading edge to rough shape before pinning in place. Pin down spars and edges and glue in all
ribs using epoxy on the metal spar only.
Notice that the hardwood wing strut mounts are located flush with the lower surface of the upper
wing and flush with the upper surface of the lower wing. Use small screw eyes cut down to receive
1/16 wire of wing struts. Fill screw holes with epoxy before installing screw eyes permanently.
The struts are held in place by tension from nylon-coated stranded fishing wire at the lower wing
strut mounts. Struts fold up against upper wing for storage. The nylon wire with crimping pliers
and metal sleeves are available at sporting goods stores. Put in extra screw eye 1/4" ahead of rear
inboard screw eye. The wire from this goes to the upper open screw eye at the nose of the fuselage.
Build ailerons along with the wing using a plywood end rib. Hinge with nylon and use round toothpicks
Cut out small area in ~6 plywood rib for aileron bellcrank to pass through. Make sure there is
no slop in aileron linkage. Cover ailerons with Silkspan.
Lower wing: Make both spars of hardwood. Note the location of lower wing tip outline on plan.
The 1/8 plywood center plate has five holes in it. The center hole is for the wing and landing gear
hold-down screw and the other four are to clear the landing gear strap nuts. Put in extra screw
eye 1/4" behind front inboard screw eye for a line that attaches to the lower open screw eye on
nose of fuselage. Wing tip skids are made removable for ease of covering and maintenance.
Make four rear and four front wing struts from 1/16 wire faired with 1/16 sheet pine or hard
balsa. Also make four fairings for cabane struts. Paint these and landing gear struts brown and
then wrap with heavy white thread where indicated on plans.
Cover both wings with silk, pulling just tight enough to remove wrinkles to prevent warping.
Cut out area just above holes in center plate for F -5 to fit into.
Tail construction: The vertical fin and rudder are 1/4 sq. balsa. Use larger hinge at bottom
of rudder to take shock from tail skid. Notice brass tube for wire brace. Bend rudder tailskid horn
from aluminum and bolt in place before bending arms down. Connect skid to rudder with small springs
from hardware store. Extend with 1/32 wire.
Horizontal stab and elevator require 1/2 x 3/8 main spars and 1/4 thick leading and trailing
edges. Taper all ribs from 3/8 to 1/4 for airfoil. Again put in tubing for bracing wire. Cover empennage
with silkspan. Line up and glue to fuselage.
Conclusion: The plane turns very well on the ground with the steerable tailskid, and combined
with the wing tip skids, it is almost impossible to turn over. Most realistic takeoffs are made
with a little down elevator to raise the tail before liftoff. For landings, feed in the down elevator
just as the main gear touches so that she does not balloon. Don't panic when the wings flex up when
pulling out of a loop or dive as they are quite flexible and strong.
H is a big bird, but once you get used to the larger variety, you will never be satisfied with
the smaller spread!
<click image for larger version>
<e-mail for 2500x1692 px version>
<click image for larger version>
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 11, 2010