Cessna Skymaster 337 Build Video/Plans

CESSNA

SKYMASTER

337/02

MAIDEN FLIGHT

VIDEO OF ALEX AND JOSH FLYING IT AT FLITE FEST

INTERVIEW AND FLIGHT, IN A FLITE TEST VIDEO.

The Cessna Skymaster is to me the creme de le creme of the civil aviation world.  It's so unique and has so much character. I just had to make one and make it close to as scale as I could, while keeping it easy to build using common Flite Test build techniques.  The outcome surprised even myself. And the way it flew was even more shocking.  The flight envelope is so broad. I can get pretty fast and rowdy with it, while it can also fly as slow as the breeze.  This plane will not drop a wing tip and will just sink perfectly during a stall.  Just like a versa wing will just glide at stall speed.  This is my favorite characteristic if this plane.. My favorite way to fly is as slow and low as I possibly can.   No matter how you fly, this will suit you.  From J.Scott to J.Bixler.      Its also a "swappable" having a powerpod.  This airframe can be flown as typical with a twin setup. Or can be used as an FPV platform with a pusher only setup.  Also could be used as a puller with a powerpod and a battery under the wing. It could easily handle a payload to drop stuff or carry cameras.      

SPECS

     WINGSPAN                59 inches

     SERVOS                      9 gram

     MOTORS                    Size 2216 .    880kv.   Twin or single .   Also can use pack C from Flite Test

     ESC                              18 Amp

     BATTERY                    2200 mah  3 cell.

PLANS

https://drive.google.com/drive/folders/0B5RrwJ2woyg6VGdna0N0N3UxbEU?usp=sharing

BUILD

The build process goes much like most of the other Flite Test designs. Simple techniques and minimal tools to build.  This plane will take 4 sheets of Dollar Tree foamboard and most of a sheet of posterboard. You will need a soldering iron for this build, so you can connect the two ESC leads together in parallel from the battery..  Only 4 connections will need soldered.    Also, WIth the fuselage carrying 2 motors the wingspar takes a bit more stress.  So I recommend buying a strip of 1/16 of an inch thick aluminum flat bar.  This can be found in craft stores, hobby shops, and all hardware stores. But the 337 I took to Flite Fest that you see in the videos, did not have metal added to the wingspar. If you try not to pull too many Gs you will be ok.   You will also need a heavier gauge pushrod for the elevator and rudder.  I use a music wire of thickness .055.      You can fly this as a 3 channel bank and yank or a 4 channel.. Ive never flown one with a rudder but it would only improve its capabilities.  So you can chose if you need 3 servos or 4.  And you can also chose to use 2 motors, or just one.  You can mount a single power pod in the front and mount the battery under the wing for CG. You can also use a single push motor in the back and mount an FPV camera in the nose.  The choice is yours. The same size motors can be use as twin or single. 

The first step is notching the 36 inch winspar at the center point   

Notch just half way though the bar and bend it, closing the gap.

Do you 50% score cutting here.

Peal out the center.

The spar goes in the gap created by folding the spar backwards

Then do the typical bevel cuts and run skewers down the score cuts.

Then tape the center of the bottom of the 2 wings together, and glue in your wingspar.

Glue each wing in halves.  Starting with the leading edge.  Glue the wing shims in before doing the trailing edge.

To build the booms, you need to create a notch in both sides of all 4 boom pieces. I use a straight edge to pry it off so I don't bend up the paper.

Start by gluing the sides to the top. Then peel the paper on the inside of the bottom piece. and close them up.   One done. you can cut your orange lines to remove the top triangle and save it.

Glue on your booms to the bottom side of the wings.  

Make sure they both touch the table and are level to the wing, so your horizontal stabilizer will be also be level.

Then glue the horizontal stabilizer in between the two booms.  

Then glue on the triangles you saved for the booms.

Get your servos centered and oriented correctly

Install your 9Gram servos in the wings and connect with typical FT pushrods. 

The pushrods in the booms are a bit thicker gauge.  I use a music wire of thickness .055.  typically can be found in 36 length in bundles of 3.

Then cut open a hole for your Rx and wires just behind the wing spar. Tuck away any lose wires and glue down any exposed wire. 

First step on the fuselage is to notch out the fuse sides. Use your straight edge to keep that edge unbent. 

Peel the paper on the inside of the two fuse sides. 

Then prebend the foam to fit the fuselage top piece.

Glue the sides on front half then back half... Starting at the nose, align the sides with the fuse top, at the nose. 

Install the power pod sleave at this point.

Peel the paper of the inside of your fuse bottom piece. 

Glue this on starting at the back half. finish with the front.   

Glue any flappy paper on your seams. Try to get this bottom edge smooth and clean looking.  

You need to add a motor mount to wingspar #7.   you can use balsa or thin plywood. Use two pieces sandwiching the foamboard between. 

Wingspars are numbered. Starting at the front.  Wing supports go in between formers 5 and 6.

Formers 5,6,and7 get support braces glued on.         Former braces 5 and 6 are doubled up and glued together.

The rear ESC will need an an extension the the power leads.  I use a 18awg wire, with a length of 34 inches. 

Heat shrink your connections.

Mount your motor, and mount your esc on the former 7 brace using double sided tape.

Now you need to solder your extension wires from your rear esc out the front of the plane. Solder your front ESC wires to your rear ESC power wires with a Battery connector. 

The ESCs are now wired in parallel, So both are getting the same full voltage of the battery.  

Mount the ESC under the powerpod.  The Battery goes inside the powerpod. With my current setup CG has the battery about 3 inches from the motor mount.

Now before we wrap the posterboard we need to check that motors spin the correct directions. REMOVE PROPS!   Best to use opposite rotating props.  Instal the Reverse prop on the back.  

Starting with the nose.. You want to pre bend it so it fits almost perfect without being held by glue.   

Then move on the to top deck. Get it bent up so its easier to glue. Start at the windshield and work back to the rear.  

A few relief cuts are needed to follow the contours. 

Then all the way back you need you few more cuts. glue it all down like a bad hair day and get your props back on.

Now you can install your wing mount posts. and cut your orange lines. exposing the esc wires and the esc that needs some fresh air from the scoop. Also bend and glue your scoop together. 

Glue your scoop on.   Now it looks awesome. 

Now set your Center of Gravity..   The CG is that small dot thats 2 inches back from the leading edge near the booms.  Check this when using different motors or single motor setups.    Now go Fly!