The Sizzle Slope Soarer A 36 inch span sloper. This is a tiny little thing. It was inspired by my trip to Point of the Mountain Utah. That's in Lehi Utah. The IMSF have a great flying site. Visit www.silentflyer.org.

The Idea: Put it down on paper. It's important to update this as you progress. This plane is being built as both a sloper and a speed 400 plane by just changing the fuselage. I want a completely clean design. So the servo linkages are in the fuselage. I use ModelCAD 98. Note::: I use rubber cement to glue photo copies of the parts to the balsa and then cut out the parts. Make sure you use Rubber Cement and do not confuse this with Contact Cement. The Rubber cement will easily rub off the part after you have cut them out. The rubber cement will also glue together sheets of balsa so you can cut out more than one part at a time. Then when you are finished cutting out the parts you can easily separate the parts and rub off any rubber cement residue. Contact Cement is pretty much permanent.

The Wing Ribs: Rubber cement two 1/16" balsa sheets together. (Use the same balsa sheet to get an equal grain and weight.) Rubber cement the photo copy of the ribs from the drawings onto the balsa. Place some weight on these until the Rubber cement sets. Then with a very sharp knife cut out the ribs. Cut short pieces of the spar and leading and trailing edges to fit as you cut each rib. Use a small sharp file to help fit these pieces. You can stack 4 or 6 sheets of balsa to make ribs for multiple wings.
The Wing: Separate the ribs from each other. Gently run the knife between each rib.

The Wing Assembly: Pin the bottom spar (1/16"x 1/4" spruce) down over the plans. Slide the rear spar (3/32"x 3/8" balsa) into each rib and place all the ribs into their position over the plans. Using pins hold the assembly in place. Place the 1/8" square balsa leading edge in place and hold it with pins. Last fit the top wing spar (1/16"x1/4" spruce). Hold in place with small weights. When everything is in place, CA everything together.

The Wing Tip, Aileron and Spar Assembly: Glue and sand the wing tip. Cut the aileron and sand the front bottom edge to a 45degree angle to allow the aileron to hinge and move down. Leave the top front edge straight. Sand the trailing edge to a taper. Cut and fit the spar shear webs. Make sure the wood grain is at a 90 degree angle to the spar.


The Wing Center Spar: Lay the two wing halves over the drawing and glue the wing halves together with 3/8 inch dihedral under each wing tip. Using 1/16 inch birch plywood cut and fit 3 pieces for the wing center spars. Epoxy the center spars in place.

The Wing Servo Installation: Note the stop blocks glued to the inside of the #1 ribs and the top of the wing center section. These blocks secure the servo in the wing. We will cover the servo area with a 1/16" balsa sheet later. Also note the servos are wrapped in masking tape. This is for two reasons. The first is to hold the servo cable in place around the rear of the servo. And second a drop of silicon glue will also help secure the servos in the wing. The masking tape will protect the servo from the silicon glue. Lastly, a piece of balsa will be glued between the servos to help hold them in place. A piece of plastic tubing is glued to the trailing edge of the wing, with a .032" piano wire as a torque rod to the ailerons. I used Sullivan Gold-N-Cable #507 tubing and .032" piano wire bent at right angles. The ball joints are attached to a short piece of brass tubing soldered to the piano wire. I don't like to cut the mounting tabs from the servos but they can be cut off and that will make their installation easier.
The Servo Setup: Any servo used on any plane has only so much travel. For discussion, lets say there are typically 256 points of movement of the servo. I have selected the inner most hole of the servo arm so that I can use the most number of points for control of the ailerons. By doing this I get the best resolution (finest movement) of my servo per movement of the transmitter stick. If you select the outermost hole in the control arm and only use a fraction (part) of the total movement of the servo arm then you may only use 100 points of movement of the servo and not have as fine amount of control over the aileron. This applies to any servo setup on any plane.



The Wing: Trim and drill the ailerons for the torque rods. The wing is completed. Some filler is brushed on and final sanding will be next. The ailerons are taped on for a final fitting and to see how smoothly they function. Make sure there is no binding.


The Fuselage, Bulkheads, Elevator and Rudder:Rubber cement the photo copy of these items to 3/32" balsa sheet and the fuselage backbone is 1/16" birch ply. Let the rubber cement dry and cut out the parts. Sand and trim to the line on the paper. Peel off the paper.Note: The fuselage is built upside down. Now pin the plywood fuselage backbone to the building board. CA the bulkheads in place. Note the center fuse bulkhead has been cut out to allow the batteries and Speed400 motor to be installed. I used a laser cut Speed400 motor mount. You can cut this from the 1/16" birch plywood.

Lay on the Keel: Starting from the tail CA a strip of 1/16"x 1/4" spruce down the center of the bottom fuse, to each bulkhead. The spruce gives just a little bit more strength to the bottom.

The Elevator Servo and Antenna tube: Clamp the elevator servo in place and CA 1/4" stop blocks. The servo will be removed and located later. There will be just too much CA flowing around to safely leave the servo here. The yellow tube is for the elevator linkage. Drill the bulkheads and CA in the plastic tube. You can tape over the ends of the tube to help prevent CA from clogging the tubes. The clear tube is for the receiver antennae to run it out the rear of the fuse. The tubes should exit the rear bulkhead 3/8" above the backbone. Leave the tubes long out the rear bulkhead, they will be trimmed short later. This is to help prevent clogging them. Note: how the fuse backbone is pinned down. The backbone must be held down secure until the bottom half of the fuse is covered.

Covering the bottom of the Fuselage: I prefer to use a stripper and cut the 1/16" balsa from the same sheet of balsa so all the pieces have about the same strength, texture and bend. That way as you lay up each piece they all bend about the same. Start at halfway up the side of the fuse and pin each piece at each bulkhead. One on each side of the fuse. When all is good CA in place. Next work back up toward the keel piece. Lay in strips about 3/16" wide. You can use 1/16" strips up to 1/4" strips. The smaller the strips the smoother the overall fuse will end up. The wider strips you use the less time it will take. I used 3/16" strips. The stripper is completely adjustable. Another note when using CA always pin each piece in place before gluing. The 1/16" strips will stick to your fingers if you tempt it. You want to leave the fuse on the building board.

The Fuselage: The bottom is laidup (Left). Remove it from the board and start on the top (Right). Once the bottom half of the fuse is laidup you can remove it from the board. It will remain rigid from now on. You can see how strong and light the fuse is. Now add the strips from the center of the sides of the fuse up to even with the top of the fuse.

Wing Mounts: Epoxy four 1/16"x 1/2"x 4" birch plywood strips together to form a 1/4"x 1/2" x 1" block. Make two of these blocks. They will be drilled and tapped with a 6-32 tap. These nylon screws will hold on the wing. On the bottom of the wing cut out the balsa sheeting to allow the wing to bolt to the front spar. A through hole is drilled in the wing for the 6-32 screw. The way I built this assembly is to make the mounting blocks, cut away and fit the blocks to the wing, drill and tap the blocks and secure the blocks to the wing with the screws. I then drilled through holes in the fuse backbone and fitted the wing to the fuse. I checked the wing/fuselage alignment and then epoxied the front mounting block to the fuselage. Be careful not to glue the screw into the mounting block. When it was cured I epoxied the rear mounting block to the backbone after again checking the wing alignment. I used a yardstick to measure from the wingtips to the center of the tail of the fuselage. Note: the access opening for the motor and batteries is cut out of the fuse backbone.
The Wing Incidence: Check the wing incidence. I use the Robart meter. The wing should be even to the fuselage backbone. Or use a ruler and measure the center of the leading and trailing edge to the top of the backbone. They should be equal. Use 1/32" birch ply glued to the front or rear of the wing (as a shim) where the mounting block is to raise the front or rear of the wing to make the wing level to the fuselage. I hope this is clear???


TheTail Feathers: With the wing mounted fit the horizontal stab. If necessary sand the fuselage where it mounts to get the stab. level and square to the wing. Epoxy or CA the stab. CA the Vertical stab square to the Horizontal stab.


TheTail Feathers and top Fuselage Covering:Split a piece of 3/16" balsa into a 45 triangle and sand and fit at the base of the vertical stab and CA in place (Left). Epoxy the two 1/16" plywood top bulkheads to the fuse backbone (right).


Cover the fuselage Top:Use 1/16"x 3/16" balsa strips and cover the top of the fuselage.


Wing Saddle:Trim off the 1/16" balsa strips of the wing saddle area. Epoxy the two 1/16" plywood bulkheads to the front and rear of the wing. Use 1/16" balsa strips to fair in the wing bulkhead to the wing.

Finish filling and Sanding:I like to use NHP Micro-Fill but probably any of the light fillers would do. I take the filler a cup of water and a brush wet the brush with water then wipe it across the filler then brush it on the balsa. This raises the grain and fills the cracks. The filler sands very easily so when it has dried sand and repeat until you have a nice smooth finish. I try to get a good finish before priming because the primer really adds weight. I like to then spray a light coat of Krylon white "Sandable" primer. Make sure you have the sandable type. When this is dry sand and lightly primer again. Any large dings can be filled with a spatula of filler and sand when dry. This is a lot of work but it is kinda a work of love. Your plane is done and you want a nice finish. I'm experimenting with some lacquer spray finishes but they are hard to get. Lacquer is nice because they dries fast but they also have a strong odor. I don't find the Krylon as objectionable. In hot dry weather the Krylon does dry fast and you get a better finish.

Notes about Sanding: This plane is so small it's hard to tell if sanding the edges does much for performance. But, the wings leading edge is small but try to round it off as good as you can a sharp edge here will cause a bad stall tendency. On the stabilizers sand the edges to a nice taper, front and rear. It will add a lot to the looks.

Painted and Trimmed:??? Will it fly . . .

Model Calc Numbers: I ran the Sizzle numbers through Model Calc. The weight is for the Speed 400 version at 16 oz. I hope for only 10 oz. weight for the slope version. So check them out.

The first flights of the Sizzle it was a little nose heavy but that's best for the first flight. After a few adjustments the performance is great. As a sloper or with the Speed 400 it flys great. rolls are snappy and inverted flight is the same as normal. Response to the flaps is very nice. When the lift gets light on the slope the flaps really help stay aloft. I had the airbrakes setup for full up ailerons but I found I had no roll control. It defenitely stopped the Sizzle but I need to back off the airbrake setting.


The tail and nose details:

The Sizzle Over Temple Hill:

Building the Sizzle To Home Page Back