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SDF - 1
 
	Tucson is located in the northern part of the great Sonoran Desert of northern Mexico and Arizona.  Most people think of a desert as a place with no water and no life.  However this is not really the case as there is life in this great expanse of land.  Many cactus abound along with shrubs and many different animal forms from the rattle snake to the coyote.  Hot in the summer and freezing cold in the winter.  Yes, we get snow on occasion here in the Sangria Desert.

  	The heat in the summer time is what attracted me to the thought of building a glider for the hot summer days.  On a good day one can launch into a thermal and soar for quite some time.  Flights of more than forty - five minutes have been recorded and log by my twin brother Gary and myself.  The design began by searching through different construction article but to no avail.  We finally decided to go ahead and design our own using most of Chuck Cunninghams formulas in RCM.  The next key factor was the K.I.S.S method of construction.  This resulted in the plans being drawn and the fabrication of two different but similar models, my brothers being all wood construction while I used  built up sections.  The model presented here is my design but all the built up parts can be solid balsa including the wing.  My model weighs less and therefore was able to preform better than the all balsa model.


  Construction:

	Let start with the wing.  We'll build the two mid sections of the wing first but try to cut out all the parts for the wing as we go along.  Start by cutting out 36 rib blanks from 1/16" balsa and two (4) from 1/4" balsa.   Make two templates using your favorite method or from 1/16" ply.  Stack the blanks together along with a template at each end and drill two 1/8" holes as shown on the plans.  Place a 3" X 3/16" carriage bolt through each hole using a wingnut to secure.  Use course sand paper sand the blanks to the shape of the airfoil.

	With the preceding step completed, lay the plans down on your work bench and cover with wax paper.  Starting with the inboard wing panels, cut the 3/16" square leading edge to length  along with the 1/16 X 2" leading edge stock.  Cut the 1/16" X 1" bottom trailing edge pieces.  Pin the 3/16" square leading over the plan and to the work bench.  Butt the 1/16" X 2" bottom leading edge in place.  Trickle a bead of C/A the along the joint to secure in place.  Pin the bottom trailing edge over the plan and to the work bench.  Now cut and pin the bottom cap strips in place.  Also cut the bottom center section and pin in place.  Remember to place in the mid center section.  When these are all in place and tight use thin C/A and glue them in place.  Pin the bottom 1/8" X 3/16" spruce spar in place and with thin C/A run a bead along each side.

	Start with the 1/4" root rib and place it in position along with the first nine (8) ribs in each wing mid section and the 1/4" mid section rib.  When in place secure with thin C/A.  Add the 1/8" X 3/16" top spruce spar and again C/A in place.  Place the top leading edge and the 3/4" X 1/16" top trailing edge panels in place and secure with thin C/A and add the 1/16" top mid section.  Finally, add the top cap strips and C/A in place.   Let the two wing mid sections stand and dry overnight before removing them from your building board.  

	Now for the fun part and I know I'm going to catch a lot of flack for this.
   			
	Building the end sections is basicilly a repeat of the mid sections.  Start by cutting the leading edge pieces and the trailing edge pieces.  Pin in place and C/A the leading edge to the bottom 1/6" X 2".  Cut and C/A the mid section in place.  Don't forget the cap strips.   Now C/A the bottom spruce spar in place followed by the cap strips.  To cut the tapered ribs begin by marking a line along the aft end of the trailing edge 1/16" from the back end using a felt tip marker.  A extra fine point Sharpie works perfect and will not leave an indent on the wood.  Beginning at rib 11, measure the distance between the back of the LEADING edge and the line you just drew.  On the rib place a steel ruler from the bottom front to the distance you measured, on the top of the rib. ( Note: See plan for detail but note this is just a detail so you have an idea of what is meant. )  Continue along in this manner for the rest of the ribs.  C/A the top spar in place along with the top leading edge and trailing edge.  Add the top cap strips and your finished for the night.  Let dry over night before removing from the board.  we'll work on the diheadril braces in the final assembly portion.

   Tail Sections:

	The tail sections are very straight forward and require little effort.  Simply cut out all the parts and pin them to the plan.  When they are all in position use thick C/A to glue them together.  The rudder and elevator are assembled in the same mannor


   Fuselage:

	First cut out all the basic parts, the sides, 1/32" doublers, and the formers.  Contact cement the doublers to the sides making a right and left side.
	
	Drill the hole for the wing hold down dowells.	Pin the right side to the board over the plans.  Thick C/A formers 2 and three to the side.  C/A the stringers in place.  Add the stringers to the other side leaving the gaps where the formers will be placed.  Unpin the right side from the board and pin it to the top view making sure to line up the center of the formers with the center line.  Pin the left side of the fuselage to the formers and only when your sure every thing is square C/A the side to the formers.  Bring the rear of the fuselage together and tape with masking tape.  MEASURE MEASURE AND REMEASURE.  PLEASE PLEASE BE SURE THAT THE REAR END OF YOUR FUSELAGE IS STRIGHT.  Don't allow one side to look like a stright line and the other side to bow as this looks like an ugle duck with a broken neck.  Both side should bow toward the center, if not find out why.  You may have to releive extra stress at some location along the back side.  Please make it stright as it will fly a lot better and won't have some strange turn that is impossible to trim out.  When your sure add the top balsa peices cross grain. Again MEASURE LOOK, MEASURE LOOK, MEASURE LOOK GLUE.
When dry pull the front together and glue the nose block in place.  Remove the assembly from the building board and glue the bottom peices on.  C/A in the wing hold down dowells.
   
   Canopy:

	Cut out the canopy floor and former 2a.  Place the floor on the fuselage and then former 2a in its position.  C/A in place and then add the 1/8" former C1.  Remove and round off C1 as detailed on the plans.  Paint the floor add a pilot if you like and finally cover with clear plastic.  I used black 1/4" trim tape to hold my plastic in place.
	 	With the canopy, you have .a choice  You can do as I did or use a solid block to cover, or just cut the upper part of the canopy as part of the fuselage and cove the opening with a 1/8" hatch.  The design can be altered and not effect preformance.  The choice is yours.
	   
   Before final assembly:
	
	Now go through and sand everything rounding off all conners on the fuselage and rounding the leading edge of the wing also round off the tail feathers.
	
	Sand in the diheadril angle for each wing center section and outer panel.  Pin the center section to the building board and block up the outer panel 5" making sure both panels fit with out gaps.  When your ready us thin C/A to bond the outer panel to the center panel.  Do the same to the other side.  Remove from the board and sand in the diheadril angle in the center section. 
Pin one panel center section to the board and raise the other 1" making sure no gap is in the middle.  When ready use thin C/A  to bond the two wing panels together.  

	Cut a strip of 3/4 oz. fiberglass cloth 3" wide and wrap the center section.  Using 30 min. epoxy thinned with alcohol fiber glass the center section of the wing.  Do the same with the mid sections of the wing only use a 1" strip and allow to cure.  C/A on the 1/4" balsa wing tips and sand to shape.

	If your going to use a Hi- Start or a winch now is the time to add the 1/8" ply inside floor be sure to cove the outside of the fuselage with 3/4 oz. glass cloth in that area for added strignth.  Add the tow hook of you choosing.
	
	Cover everything, I used red Monocote and added black trim tame to complete the covering.  I also used trim tape to hold the canopy in place on the fuselage.   Glue on the horizonal stablizer and the verticle stab.  I used Monocote hinges to add the rudder and elevator.
	
  Flying:
	Install your radio and charge your batteries and your ready to fly.  Be sure to balance the model at the C/G.  The SDF-1 is at home on the slope as well as for hunting thermals here in the southwest.  But if you added the tow hook for a hi-start or winch be sure to use the lower power hi-starts and winches.  Don't try to pull the wings off the model when launching.  If kept as light as possible with out compromising integraty you will be rewarded with many hours of fun flying.

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