Guillow's Cessna 172 Skyhawk
  Claimed by its maker the Cessna Aircraft Co. of Wichita, Kansas to be the best selling single engine airplane in the world, the Skyhawk can take four adults and their baggage at 134 M.P.H. for 450 non-stop miles and still have 45 minutes of reserve fuel. Over 17,000 of these aircraft are in service around the world. Model 172 specifications: wing span, 35’-10”; wing area, 175.5 square feet; length, 26’-11”; height, 8’-9 ½”; service ceiling 13,100 feet; power, 4 cylinder engine 150 rated H.P. at 2700 R.P.M.; speed, at sea level, 139 M.P.H.

 
 
 
Specifications of My Electric Conversion of the Guillow's Cessna 172 Skyhawk.
Wing Span 36"
Wing Area ~ 170 sq.in.
Weight Airframe and RC gear only   10.5 oz.
Weight Ready to fly 18.125 oz.
Wing Loading 15.4 oz/sq.ft.
Covering red monokote, white econokote
Motor 7.2V S400 direct drive
Propeller 6.5x4
Battery 7 x 600AE Sanyo
Controls Rudder, Elevator, Aileron, CS10BB servo, 
Castle Creations Pegasus 35 ESC
Receiver Hitec 555
Custom Features Spring loaded quick release wing-strut keepers, Wing struts: aluminum airfoil tubing,
Pull-pull elev. & rudder controls using 0.016" steel cables

 
 
 
Here's how it looked as it was when first completed. The propeller here is a 7x3 wooden one re-carved to a thinner profile airfoil with some "undercamber".  The wheels are the cheapie wooden mains and styrene plastic front that come with the kit.
I went with the scale wing dihedral angle for appearance and to retain lift efficiency since the wing area is small. 
Now it has a Graupner precision spinner/motor shaft adapter and Graupner 6.5 x 4 propeller. This is the combo used on the first flight and it provided very good speed performance and a reasonable ROG takeoff distance of less than 100' on asphalt pavement.
My "high tech" motor mount consists of two 1/4" birch dowels extending through lite-ply plates on the front two fuselage formers. 
The aileron servo is seen here in the center of the wing. Linkages are via torque rods.  I will probably change the servo control arm to enable differential throw for more up aileron than down. 

The wing has no main spar but rather several 1/16" square top and bottom stringer type spars. I upgraded those to 1/16"x 3/32" and sheeted the front 1/4 of the chord from the leading edge back with 1/32" balsa.  I also implemented a screw down wing attachment method using #12 nylon screws.
"Bounce" testing of the wing with a fully laden model revealed that it was still not strong enough so functional struts were added made from  aluminum airfoil tubing. Since the wing needs to be removed to access the battery I made spring loaded quick release wing-strut keepers so I don't need tools. More details on the struts are here.
This kit included a transparent vacuum molded cabin section to which the wing is mounted with rubber bands and dowels . This didn't look strong enough to me to withstand the stresses of a 18 oz speed 400 powered plane.  Also I needed an access opening for the flight gear.  So I built a cabin structure from  light-ply, spruce and balsa then removed the top section of the plastic cabin. The ESC can be seen attached with velcro to the "instrument panel".  Also visible are the rear of the motor mount dowels protruding through the plywood cross brace.
The receiver mounts with velcro to a platform between the servos. The 7 cell battery is likewise held down with a generous peice of velcro onto a platform integrated into the landing gear block. The reinforcing  at the landing gear section  also extends up to the wing srew down points.  There is plenty of volume inside for whatever flight gear or battery I could want to try. 
The vertical stabilizer presented a particular difficulty with control linkage because of its swept back design.  When it turns, the arc of the control horn goes horizontally and vertically. This makes a solid control rod work poorly as a very large exit hole would be required and there is more slop in the control action.  I solved this by using pull-pull control cables. Since they are so flexible only the last two inches has to bend and tiny guide tubes are the only entrance into the fuselage.
Other Guillow's conversions
Stearman PT-17
British SE-5A 
Lockheed P-38 Lightning

Contact: geraldod@bellsouth.net