Manual

Our Pawnee will be assembled with all of the Hangar-9 recommended components with just a few minor deviations.  I'll note any deviations as we go along. Where adhesives are required I'll be using Zap brand CA and Pacer Z-Poxy 5 and 30 minute epoxies and RC-56 canopy glue.  Remember that  when you are working with modeling chemicals and adhesives be sure you have adequate ventilation.

When building or repairing a gas airplane, always use thread locker on ALL metal to metal connections!

Before you unpack anything make sure you have enough room to work on the Pawnee.  The wing panels are 60" long each with a 20" chord, and the fuselage is nearly a foot wide and over 90" long.

Once I had my work area laid out I set up a new model in my JR 11X 2.4gHz radio and bound it to a Spektrum 12210 Power Safe receiver.  The 11X (as well as several other of the high end radios) makes setting up multiple servos for one control a snap with the surface mating feature.  The Pawnee uses 2 aileron servos, 2 flap servos, and 2 elevator servos.  Using the mating feature eliminates setting up a program mix and ensures that any trim or mixing applied to the master channel affects each surface equally.   Having the radio ready to go allowed me to set up each control surface as the build moved along.

Wings

The first step to building the Pawnee is assembling the massive wing panels.  Remove and mark each hatch for location and orientation and use the provided hardwood blocks to install the servos.  If you're using the Spektrum servos and JR arms the servo arm comes with a hex head screw that replaces the easily stripped phillips head screw provided with the servo.  To complete the installation I used the hex screw from the servo arms and the star washer from the hardware provided with the servos. 

When installing the aileron servos the recommended servo extensions are perfect.  Also there is string provided to pull the aileron servo extensions through the wing.  Use some heat shrink or dental floss and secure the servo extensions to the servo wires so nothing becomes disconnected at an inopportune time.

The flap servos didn't get the factory string and I think there's a misprint in the manual because the indicated 3" extension for the flap servos is barely long enough to reach the wing root and I replaced them with 12" extensions.  I could probably have gotten away with 6" extensions here but the 3" were definitely too short.  I used a piece of music wire with a hook on the end to fish the wires through for the flaps but a string and large nut would work just as well as it's a straight shot through the ribs to the wing root.

In the "wow that's a nice touch" department, strings are provided to pull lighting wiring through the front of the wing if you wish to add a scale light kit to your Pawnee.  I have a set of E-Z Lights on order from East Coast Vario but they were not received in time to make the review.  I did glue the included clear lenses on with RC-56 canopy glue so that they would be easy to remove once it was time to add the lights.

Installing the 4 control horns is straightforward.  I found it convenient to have an electric screw driver on hand to run the counter-sunk screws through each control surface.  These call for epoxy and whenever you use epoxy around the Pawnee's nice white covering job, take care to have some alcohol and clean paper towels handy to remove any excess glue before it has a chance to set up.

The wing jury strut installation is where I ran into one of the very few problems I had with the kit.  With the attachment points installed on the wing as indicated, and the struts oriented correctly (I checked several times to make sure I wasn't doing something wrong), the strut simply would not sit far enough into the mount for the screw to clear.  I reluctantly took the struts to my bench grinder and had to remove about half of the material between the bolt hole and the bottom of the strut so that the bolt would pass through both the mount and the strut. 

The Pawnee kit uses a set of bolts, fuel tubing, and cotter pins to attach the struts to the wing.  The fuel tubing slips over the bolt and when the bolt is passed through the hole and the cotter pin is installed, the tubing compresses and keeps everything tight.  The same connection is used to attach the struts to the fuselage during field assembly and I found it to work very well.  In fact, I saved one of the clear servo boxes and carry the bolts, cotter pins, wing bolts, and front hatch bolts all in one place when the Pawnee is disassembled for transport.

When you have everything connected, install the strut covers with RC-56, tape them down with painters tape and when the glue is dry the wings are done!

Generous hatches are provided at the rear of the plane for both servo and battery access. The Pawnee uses one servo for each elevator half and a pull pull system for the rudder.  Considering where the CG ended up on my plane even with the heavy spring starter components removed, I'm glad they designed the plane with rear mounted servos in mind.  The battery tray was just an added bonus or I surely would have been fabricating one back there.

When you build the pull pull rudder cables the manual recommends a crimping tool for the brass sleeves.  I didn't have one handy so I simply used vice grips.  One thing I did end up doing that made it harder on myself than I needed to was to try to use the least amount of cable possible on the servo end to make the connections.  I need not have worried as there was plenty of cable left over and its easier to have a little more cable and cut off the excess when you're done.  Take care to thread the cable fittings into the ball link ends equally so you end up with the proper geometry when you're done.

If you read ahead in the instruction manual you know that you're going to install the tail struts to the two forward servo hatch bolts later on.  You can either fish two of the brass strut fittings out now and install them, or leave them for later.

When you're done buttoning up the tail it's time to move on to the scale landing gear. 

Hangar 9 took the time to faithfully reproduce functional scale landing gear for the Pawnee that replicates the real thing while being very easy to assemble.  There is no bending, soldering, or fussing; the whole thing goes together like an erector set.  Add the large tires and the Pawnee should be able to handle almost anything that resembles a runway.

About the only advice I can give you is to make sure the bolts are tight enough so there's no free play, while not so tight as to prevent the gear from freely articulating.  Where the shocks mount to the frame up inside the fuselage, use a good thread locker and use caution not to over tighten the bolts where they thread into the blind nuts.
 

The scale landing gear is one of the features that has gotten the most attention from folks looking (drooling really) over the Pawnee at the flying field.  The shock absorbers are so cool it's a shame they are buried up inside the fuselage.

On the subject of easy to assemble, the stabilizer and elevator installation is about as simple as it gets.  The elevators are pre-hinged at the factory like the flaps and ailerons so that chore is already done for you.  Simply fit the tubes in the correct holes (short one to the front) and bolt the stabilizers in place.  I double checked the incidence when I was done and they were square and dead on.

Assemble the elevator pushrods just like the ailerons.  The Hanger 9 ball links, standoffs, and turn buckles are of very high quality and I haven't had any issues with the hardware in this kit.  Though it wasn't specified in the manual, I went ahead and applied epoxy to the bolts here as well where they went through the elevators.

When assembling the elevator servo arms, make sure everything is sub-trimmed so that the arms are 90 degrees to the servo body on both sides.  If you try to eyeball this you're likely to have uneven elevator throw.  Attention to detail here will pay dividends later on.

The tail wheel bracket and hardware appear robust enough to take the rigors of every day Pawnee flying.  The rudder and servo are isolated from the tail wheel by the use of springs.  The springs provide tail wheel steering while not passing the shocks of landing on to the servo gear train.

When you're done installing the tail wheel it's time to make up the eight tail strut rods.  I'm not sure if they are functional on the model but while it's a little bit tedious getting them all tight enough not to rattle while not being too tight, it's worth the effort because they really do look good when you're done.  They are a scale detail that is included on the full scale Pawnee in any case.

It's time to prepare the rudder for installation.  The rudder is the only surface where you have to install and glue hinges but the holes are already drilled for you.  In order to prevent inadvertently gluing the hinges I coated the pivot points with Vaseline petroleum jelly.  Also, since you're going to use epoxy to install the hinges you can work with one side at a time to make sure the alignment is perfect.  I glued the hinges into the rudder and when they were dry I installed the rudder to the fin.

Attention to detail is again required when building the control horn for the rudder.  Measure everything carefully and you will end up with a perfect pull-pull system.  Slack should be taken out of the cables such that they have no visible slack but neither should they be as tight as banjo strings.  If you can feel slop in the rudder with the servo powered up, then you have too much slack, if the servo is always buzzing the cables are too tight.

Once you rig up the tail wheel steering springs it's time to move on to the business end and get some horse power installed!

I have been using rubber sealing washers to mount fiberglass cowls and in other applications on gas airplanes for some time now.  I was really glad to see that Hangar 9 included sealing washers to hold the cowl and hatch of the Pawnee in place.  These hold well and don't eat away at the fiberglass and most importantly; they stay put.

If you're running the Zenoah engine there is a cut out for a throttle servo right on top of the motor box..  To get proper throttle geometry my engine guy ended up making an extended throttle arm (it pays to be friends with a machinist!).  I have always found the carb arms on our gas engines annoyingly short and nearly always install some sort of extension so I get increased end points for better throttle resolution.

To actuate the choke I considered adding a separate choke servo underneath and I had one channel left on my 11X but in the end I elected to stick to the manual method. 

Though it's not documented in the manual, located in the fuel tank access area are servo cut outs that are provided if you use a different engine and the top mounted throttle servo won't work for you.  They also provided a pushrod for that purpose.  I purloined that pushrod, cut it off, and ran it out the bottom of the cowl and attached it to the choke actuator.  Its nearly invisible and works like a champ.  When I found out I was nose heavy even with the removal of the spring starter parts and two batteries in the tail, I was glad I didn't add any more weight to the engine compartment.

The stock GT-80 magneto plug caps will fit completely inside the cowl but the electronic ignition conversion included longer plug caps that required a little cowl hacking.  When the plug cap was clear we went ahead and mounted the mufflers, made a template from manila folder, and cut out the cowl for the exhausts.  There's a pretty generous area between the bottom of the fuselage and the bottom of the cowl so I thought we had enough exit area for the cooling air to flow out of the cowl.

Tru-Turn provided a gorgeous aluminum 3 3/4" P-51 style spinner which looks terrific on the Pawnee and matches the cowl perfectly.  They also sent along the proper propeller adapter bolt.  The drive plate on the Zenoah has pins that fit into the predrilled hole in the spinner back plate and the entire system has been flawless.

The fuel tank was already assembled and mounts in the generous front area right on the center of gravity.  I mounted the tank on self adhesive foam insulation strips available from any home supply store.  The only modification I made was to cut the feed line to the carb and install a Tee fitting along with a Gem-Dot machined fuel dot.  Use tie wraps or safety wire on all of the connections as tygon fuel line can swell over time.  The vent line was routed to the bottom of the cowl and I installed a rubber grommet for it to pass through.

When the time came to put everything together I found the second area of my kit that needed some extra work.  With the aluminum wing joiner installed on the right wing and the wing slid up to the anti-rotation pins, only one pin would seat, the other pin wouldn't align.  I had to use a Dremel tool and a sanding disk to open up the hole, top to bottom a bit.  Fore/aft alignment was fine.  The left wing was out even farther.  Before I set to work on the holes I used a incidence meter to see whether the front or back needed to go down a bit.  It turned out to get equal incidence I needed to enlarge the back hole slightly.

An RCExcel optical kill switch was installed and the receiver was bound such that the throttle was set to full low and the ignition was set to kill in the event of a fail safe event.

There are switch cut outs provided all over inside the Pawnee.  You merely have to decide where you want your switches based on your particular radio equipment layout.  One of the things I really liked is that the switch cutouts land squarely on the blue stripes so they don't stand out like sore thumbs on the white.  I installed the soft switch for the Power Safe receiver and the JR Heavy Duty Charge Switch for the ignition system.  Hangar 9 provided both the large and small switch cutouts so it's clear the equipment flexibility extends to the radio system as well as the engine mounting.  In addition to the switches I drilled a small hole and mounted the LED indicator light for the electronic ignition system and the Gem-Dot fuel dot.

The last thing to install was the Red Aero RC pilot figure.  I fabricated a deck made out of plywood and epoxied it to the bottom of the cockpit window rails.  The pilot bust was secured by making a plywood stringer and attaching it with self tapping wood screws.  If I had realized in advance I was going to be making this deck in the cockpit, I would have mounted the switches for the radio on the the deck the pilot is sitting on to clean up the outside of the fuselage.

It came as no surprise that it took two of us to balance the big Pawnee.  With the batteries initially sitting below the cockpit the Pawnee was seriously nose heavy.  I soldered up extensions for the batteries and installed them in the rear access hatch.  This was a lot better but it still required 3 full sticks of Kwik Stik lead as far back as I could hide them.

Tow Rig Installation

Since the Pawnee was going to be doing duties similar to its full scale counter part, IFlyTailies.com provided a glider tow relase for the review.

The tow release is made in Germany and appears to be very sturdy and very high quality.  This release is unique in that it is a two step release that can be used for a number of applications aside from glider towing or could even be used for towing more than one glider.

Installing the tow release in the Pawnee meant removing two bays of covering on the bottom and some of the foam that is applied to the balsa sheeting on the turtle deck.  Once we got down to bare wood where we were going to glue, we built a bulkhead and supports out of plywood.  Once the bulkhead and support were glued in place we fabricated a mount for the servo out of plywood.

When everything was checked and double checked I recovered the bays and headed to the field to do a day of glider towing.

While the above steps make it sound simple, it took two of us about 8 hours of work to custom fabricate, glue, and test everything related to the glider tow release system.  Since this was beyond the scope of assembling and flying the Pawnee for the review, I did not count this time towards completing the project.  Indeed, the review flights were done the weekend prior to the installation of the tow release and the glider towing portion of the review.  Thanks goes to my engine guy Joey for his help and expertise in modifying the Pawnee for the tow release.

The Pawnee is a natural glider tug as you will see from the videos we shot with the GoPro HD camera.  I have flown a number of tow planes and the Pawnee gives a very stable and predictable tow and it's generous fuel tank has plenty of capacity for knocking out several tows before needing to land and refuel.  The day we shot the video we were towing a quarter scale KA8B built and flown by Steve Betts of Jacksonville.  We have a number of scale gliders in our club so the Pawnee will be doing regular tow plane duty.