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Pietenpol Air Camper
Written by Pat Tritle
Construct your own "homebuilt" aircraft
Construction
As seen in the October 2017 issue of Model Aviation.
Download free plans!
Full-size plans
Click here for full plans - Sheet #1 (48.03 x 36.01")
Click here for full plans - Sheet #2 (48.03 x 36.01")
Tiled plans
Click here for tiled plans - Sheet #1 (24 8.5 x 11" pages)
Click here for tiled plans - Sheet #2 (24 8.5 x 11" pages)
Specifications
Wingspan: 48 inches
Length: 30.25 inches
Wing area: 400 square inches
Flying weight: 14.7 ounces
Wing loading: 5.3 ounces per square foot
Power system: Suppo 2208/17T brushless outrunner; Suppo 18-amp ESC; APC 9 x 6 DD
propeller
Battery: Hobby People 1,300 mAh 2S LiPo
Radio system: JR XG8 transmitter; RG411B receiver; four Suppo 6-gram submicro servos;
one 11-inch servo Y lead; two 9-inch servo extension leads
Materials List
Wood
Nine 1/16 x 1/8 x 36-inch balsa
One 1/16 x 3/16 x 36-inch balsa
One 1/16 x 3/8 x 36-inch balsa
One 3/32 square x 36-inch balsa
Two 3/32 x 1/4 x 36-inch balsa
One 1/8 x 1/4 x 36-inch balsa
Nine 1/8 square x 36-inch balsa
Nine 3/16 x 3/8 x 36-inch balsa
One round toothpick
If Laser-Cut Parts Pack Is Not Used
Two 1/16 x 4 x 36-inch balsa sheet
Two 3/32 x 4 x 36-inch balsa sheet
One 1/8 x 4 x 36-inch balsa sheet
One 1/8 x 4 x 10-inch light plywood
One 1/32 x 2 x 4-inch plywood
Metal
One .025 diameter x 18-inch steel wire
One .032 diameter x 24-inch steel wire
One .062 diameter x 36-inch steel wire
One 1/16 OD x 6-inch aluminum tube
One 5/32 OD x 24-inch brass tube
One 3/16 OD x 18-inch aluminum tube
Miscellaneous
One pair 3-inch spoke wheels
One 3/4-inch tail wheel
One .032-inch inner diameter
x 14-inch plastic tube
10 feet of heavy-duty nylon thread
One blue foam block
One 2 x 4-inch window screen
One manila file folder
One .008 x 2 x 4 acetate sheet
Construction
The Pietenpol Air Camper is a two-seat, high-wing parasol homebuilt monoplane designed in
1932 by Bernard Pietenpol and was featured in a four-part series titled 1932-33 Flying and
Glider Manual. The prototype was powered with an Ace four-cylinder, liquid-cooled engine,
but the Ford Model A later became the engine of choice.
In the 1960s, a number of modern car engines were used. The best choice was the Chevrolet
Corvair air-cooled flat-six. Since that time, a number of engines have been used in the Air
Camper, including conventional Continental and Lycoming airplane engines.
The Air Camper is a relatively small airplane with a 29-foot wingspan. The airplane is built
primarily from wood with a few metal fittings that need to be fabricated by the builder. In many
cases, motorcycle wheels are used on the landing gear. With a top speed of 100 mph and a
cruise speed of approximately 75 mph, the Air Camper is not fast, but after spending some
time in one, flying low and slow in an open cockpit is an experience not soon to be forgotten.
The Model
The model was designed with a 48-inch wingspan at 1:7.25 scale and is a lightweight,
electric-powered park flyer that is well suited for small fields and parks, and can be easily
flown within the confines of a soccer field or a baseball diamond. With a wing loading of
slightly more than 5 ounces per square foot, the model is a slow and docile flier, and although
not particularly large, the Pietenpol is big enough to add plenty of scale detail without adding
unnecessary weight that could rob it of its inherent gentle flying qualities.
Power is provided by an economical Suppo 2208 series outrunner motor with four-channel
control using four submicro servos to run the rudder, elevator, and ailerons.
The design is basically old school in that the fuselage and tail section are “stick framed” much
like old Comet kits. The egg-crate-style built-up wing has the ribs notched into vertical spars to
make building it quick and easy.
To maintain scale rib spacing, false ribs are used between each of the full ribs to keep the
weight in check. The model features plug-in wings and lift struts that can be quickly and easily
removed for transport without needing tools or easily lost hardware.
Full-size parts patterns are provided on the plans for scratch builders. For those of us who
prefer laser-cut parts, a wood pack is available from Manzano Laser Works.
With all of that stated, let’s build a Pietenpol!
Tail Section
Lay out the vertical and horizontal stabilizers directly over the plans. The perimeters and hinge
spars are 1/8-inch square balsa with the ribs laid in using 1/16 x 1/8-inch balsa and scrap 1/8-
inch balsa to make up all of the corner gussets. Hinges are made from small strips of CA
hinge stock and slotted into the spars using a hobby knife. They are dry fitted in the spars.
The built-up tail section is traditional stick-frame-style construction. A tail wheel was incorporated, rather
than using the original tail skid to improve ground handling.
Wing
With all of the wing parts at hand, pin the servo-mount plate A3 in place over the plans. Dry fit
ribs R1 through R7 over the main spar A1 and rear spar A2, pin the assembly in place over
the plans, and then secure each point of contact with thin CA adhesive.
Align and glue R4A and A5 in place followed by the 3/32 x 1/4-inch balsa trailing edge (TE)
and 3/16 x 3/8-inch balsa leading edge (LE). Fit and glue A8A and A8B in place using the R7
rib detail drawing for reference. Align and glue A4 in place on A3, and the 3/32-inch square
balsa diagonal brace at the root aligned with the TE and the top of A2. Finally, align and glue
each of the FR1 and FR2 false ribs in place.
The egg-crate-style built-up wing makes building quick and easy. False ribs simulate the scale rib spacing
without adding unnecessary weight.
Build the ailerons in place on the wing assembly. Begin by sanding the bevel into the bottom
of A5 using the R5 rib detail drawing for reference. Align and glue AR1 in place followed by
the outboard AR2 rib and pin the assembly in place on the TE followed by the remaining AR2
ribs and A8C. Sand a bevel into the front edge of A9 and glue it in place flush with the bottom
of the aileron.
Remove the wing assembly from the board and sand it into rough shape. Align and glue A7 in
place and sand the assembly to final shape. Cut the ailerons free from the wing assembly and
sand it to final shape. Cut the hinges from CA hinge stock and fit them into the spars referring
to the R5 rib detail drawing.
Tack glue the 1/16-inch outer-diameter (OD) aluminum strut retention tubes in place on A3
and A7, lash the tubes in place with nylon thread, and harden it with thin CA. Cut the 3/16-
inch OD aluminum wing retainer tubes to length and glue in place at R1 and R2. Mount the
aileron servos using silicone caulk. When that is dry, run in the extension leads to complete
the wing assembly.
Build the wing center section directly over the plans. Begin by pinning CSM2L and CSM2R in
place over the plans. Dry fit CSR1 and CSR2 in place on CS1 and CS2 and pin the assembly
in place over the plans. Secure each point of contact with thin CA glue.
The finished wing panels are plugged into the center section for a trial fit after all of the components have
been built.
Align and glue the LEs and TEs in place, then remove the assembly from the board and sand
to shape. Fit and glue the two CSM1s in place, sand to final shape, and then fit and glue the
5/32-inch OD brass wing joiner tubes in place.
Fuselage
Build the right-hand fuselage side frame directly over the plans. Pin the 1/8-inch square balsa
longerons and vertical and diagonal bracing in place, followed by all of the 1/16 x 1/8-inch
vertical and diagonal bracing.
Glue PRG in place flush with the outside edge. Remove the frame from the board and build
the left-hand frame. Align and glue LG1 and LG2 in place on the inside of each of the frames.
Make up the landing gear mount beams using the detailed drawing provided.
To join the frames, pin them upside down over the top/bottom view drawing and glue the
landing gear beams in place. Use squaring blocks to ensure that the frames remain vertical.
The fuselage side frames are built up then joined, beginning with the landing gear beams. Squaring blocks
are used to ensure that the assembly starts out straight and true.
Lift the frame from the board and pin it over the drawing at the rear landing gear mount beam.
Support the aft end with a balsa or blue foam block and glue formers 1 and 2 in place on the
top of the frame, followed by the 1/16 x 1/8-inch bottom crosspieces from former 2 forward.
Using the squaring blocks, pull the tail ends together and glue. Add formers 3, 4, 5, and 6 and
the bottom 1/16 x 1/8 balsa crosspieces.
Build up the cabane strut mounts from CSM1 and CSM2 and glue them in place on the frame.
Fit and glue each of the 1/16 x 1/8-inch balsa stringers in place between the two forward and
two aft former 1s and from former 2 through former 6. There are no stringers in the front and
rear cockpit sections.
The frame assembly is pinned to the board right side up and the tail section pulled together using
machinist’s squares to ensure proper alignment.
Remove the 1/8-inch square balsa vertical brace where shown on the framing plans and fit the
firewall FW in place. Build up the motor mount from MM and two MM1s and glue it in place on
FW. Next, crack the longerons at FW and glue the 1/8-inch balsa crosspieces in place at the
front. Again, glue the longerons at the breaks, and then mount the motor and ESC.
Align and glue the servo mount rails in place, followed by the rudder and elevator servos,
using the servos to determine the beam spacing. Run in the elevator pushrod tube supported
at the rear PRG and the front and a couple of points in between using the PRSO stand-offs.
Using the continuous rudder pull/pull cable routing diagram, run the rudder cables into the
fuselage. Tape the tail section in place, tie off the rudder cables to the control horn, and mark
the exact location on the plans where the cables exit the fuselage.
Align and glue the 1/16 x 1/8-inch balsa side stringers in place, followed by the balsa fill at
FW. Make up the paper side, bottom cowl skins, and the cockpit fairings from file folder paper
and glue them in place. Follow that with the nose block to complete the fuselage assembly.
Bend the landing gear to shape and solder it together directly on the fuselage. Lash the gear
to the mount beams with nylon thread and harden with thin CA. Align and glue the 1/16-inch
OD aluminum tube strut fittings in place, lash them with nylon thread, and secure the
assembly with thin CA glue.
The cabane struts are fitted into the fuselage and a wing alignment jig is used to ensure the proper
incidence when the wing is installed. Dry fit the wing to check for proper cabane strut alignment before the
model is covered.
Bend the cabane struts to shape using the provided patterns and slip them into their
respective mounts. Make up the wing alignment jig and pin it in place on the fuselage
centerline. Slip the wings onto the center section and fit the wing assembly onto the cabane
struts. Build up the lift struts according to the assembly drawings and fit the struts in place.
Covering the Model
Before applying the covering, do a final dry run to ensure that everything fits and functions
properly. If you find any problems, fix them now while things are still easy to access. Do a final
detail sanding to remove any flaws.
All of the frames are covered except for the top of the wing’s center section. When all of the
covering is attached, glue the hinges in place.
Final Assembly
Pin the wing alignment jig in place, fit the wing assembly onto the cabane struts, and attach
the front lift struts. Align and glue the center section in place, then pot the cabane struts in
place on the inside. Fit the rear struts in place, which will set up the washout to roughly 1°.
The wing struts are dry fitted to ensure proper alignment. The struts can be easily removed without tools or
special hardware.
Remove the struts and wing panels and run the aileron servo Y lead into the fuselage and
center section and then cover the top of the center section. Reinstall the wings and struts and
glue the tail section in place using the wing for reference.
The tail brace wires are added using nylon thread. Run in the .025-inch elevator pushrod and
secure it to the servo with a Z-bend.
Make a Z-bend at the elevator hinge line, align the control horn in the neutral position, and
glue it in place. Run in the rudder cables and tie them off at the control horn. Connect the
ailerons using a .032-inch steel wire pushrod with a Z-bend at both ends.
The rudder and elevator servos are located in the rear cockpit for easy access. The elevator is driven using
a pushrod and the rudder uses pull/pull cables.
Adding Details
Build up the scale Model A engine from blocks of blue foam, aluminum tubing, wood dowel,
and whatever other parts will work. The radiator is built up from balsa and 1/64-inch plywood
or sheet styrene. Build up the dummy engine mount using the detail drawing for reference and
tack glue it in place.
Glue the top cowl section in place followed by the scale engine, radiator, and any additional
details desired. Make up the windshield from .008-inch acetate using the provided pattern and
glue it in place.
Construct the landing gear fairings from 1/16 x 3/8-inch balsa and cabane strut fairings from
1/16 x 3/16-inch balsa and glue them in place. Make the cockpit combing from 1/2A silicone
fuel tubing and then mount the main wheels and tail wheel to complete the model.
The motor is mounted and then the cowl skinned using file folder paper. The upper cowl section will be
added after the center section has been installed to allow clearance for the alignment jig.
Balance and Control Setup
Balance the model 2 1/2 inches from the wing’s LE using the battery to your best advantage.
Make the battery tray from 1/8-inch light plywood and glue it in place. Velcro the battery to the
tray with.
Make up the battery hatch cover from .010-inch styrene and 1/8 x 1/4-inch balsa using the
provided detail drawing. The hatch cover clips in place between the landing gear beams.
Finally, set the control throws as shown on the plans, and the Pietenpol is ready to fly.
The subassemblies have been fitted and detail sanded in preparation for covering. The dry run is important
because problems are much easier to correct before the covering goes on.
Flying the Model
Before you fly your Pietenpol Air Camper, check again to ensure that the motor is turning in
the right direction and that the control throw and movement are correct. With a freshly charged
battery, point the model into the breeze and advance the throttle to roughly 2/3 power.
When the aircraft is ready to fly, add a touch of up-elevator and it will lift off. Maintain a
shallow climb to a safe altitude and trim the model for straight and level flight at a comfortable
cruise speed. The model flies well, and is a gentle flier, and it responds nicely to control input
with little or no adverse yaw from the ailerons. The Pietenpol also turns well only using the
rudder.
After getting a feel for how the model handles, try a couple of stalls. I found the stall to be
uneventful, and when carrying a bit of power, it will simply mush along. Set up the landing,
reduce the power, and start the descent. Upon final approach, you’ll want to carry a bit of
power. At a foot or so above the runway, raise the nose slightly, gently back off the power, and
let the model settle in for a three-point landing. The Air Camper also does well with wheel
landings.
When you get used to how the Pietenpol handles at low speeds, try a few touch-and-gos.
In flight, the Air Camper is a gentle and docile flier that is well suited to smaller flying venues.
If it’s a nice, relaxing, well-mannered model you’re looking for to fly on small fields, this classic
1930s-era homebuilt Air Camper is just what the doctor ordered.
—Pat Tritle
patscustommodels@gmail.com
Sources:
Hot Deals
(503) 766-4119
www.rchotdeals.com
National Balsa
(413) 277-9500
www.nationalbalsa.com
Hobbylinc
(888) 327-9673
www.hobbylinc.com
Pat’s Custom Models
(505) 296-4511
www.patscustom-models.com
Manzano Laser Works
tomj@tularosa.net
www.manzanolaser.com
