Science

Strake Installation

The strake looks like little wings on the side of the plane. They are fuel tanks built into the wing desing know as wet wings.

Level the plane. Mark the location of the lower strake on the fuselage at the bottom of the wing strut and mark this height at the front of the fuselage.  Chalk line the two points making sure the line is level. Attach the aft edge of the strake to the lower edge of the wing strut. Raise the leading edge of the strake 2 1/4" above the bottom of the aft edge of the strake. Mark the location along the fuselage where strake touches.  Sand the fuselage 8" wide  and the edge of the lower strake to the fiberglass. Glass the lower strake to the fuselage and the wing strut with micro-glass and 4 bid.

Bulkheads/Baffles

Bulkheads are the outside barrier of the fuel tank. Baffles are the walls in the fuel tank that reduce fuel slosh during flight.

Cut the bulkhead and baffles out of the 3/8" foam board using the over sized patterns. Cut 2 sheets of fiberglass cloth for each piece. Mix micro-bubbles the thickness of peanut butter and spread it on one side of the foam with a spreader. Place the fiberglass cloth on top of the each piece and smooth out. The cloth should be wet with a thin layer of epoxy. Place peel ply on top and smooth out with speader. Let cure and repeat on the other side.

Sand the inside of the lower strake. Mark the locations of the bulkheads and the baffles. Glass the bulkheads in place first with micro and 2 bid. After cured tape the baffles in place.  Place a light in the strake. Lower the upper strake onto the baffles and looking through the edge of the bulkhead for high areas. Form the baffles to the shape of the upper stake with a sanding block. Cut mouse hole in the upper and lower edges of the baffles. Glass the baffles in place, bottom and side with micro and 2 bid.

Flange

Create a flange for the top of the bulkhead and baffles, optional. Mark the location that the bulkhead and baffles meet the upper strake. Place a layer of duct tape down each of the lines. Make a wet lay-up of 1.5" wide fiberglass tape. cover the top and bottom with peel ply. Place the strips of glass on the duct tape and let it cure to the shape of the upper strake. Lay a bead of Micro on top of the bulkheads and baffles. Remove the peel ply from the bottom of the fiberglass strips. Lay the strips on the bulkheads and baffles. Place the upper strake on the lower strake and tape down. Let cure and remove. Reinforce the flange with a bead of micro on both sides. Sand the edges of the flange flat.

Fuel Tank Coating

Sand all the surfaces inside the fuel strake. Clean the sufaces. Mix up the Jeffco with a little cabosile to keep pinholes from forming. Paint the inside of the the fuel strake with jeffco using a paint brush. Add a second coat when the first gets tacky. Place the fuel screen over the fuel outlet and secure it in a bead of Jeffco.  Let cure.

Upper Strake Installation

Sand all surfaces that will touch the inside of the top strake, top of flanges, front of lower strake leading edge, side of fuselage and top of wing spar and matching wing edge. Clean all the surfaces. Remove the peel ply from the upper surface of the flanges. Mark the location of the bulkheads on the upper strake. Mix the Jeffco and cabosile and paint one coat on the upper strake to just past the bulkhead marks. Mix strauctural adhesive with cabosile and place a bead on the mating wing surface and the top of the wing spar.  Place a mixture of Jeffco and flox into a one gallon Zip Loc bag. Cut off the tip of the bag and squeeze out a ½ inch high bead on the top of the flanges and the front edge of the lower strake. Paint a second coat on the upper strake. Spread a layer of Jeffoc flox mix inside the front edge of the upper strake.  Jeffco starts to cure in 1 hour so work fast.

Carefully put the top skin in position. With a person in the front and back of the strake hold the back up at a 45 degree angle and lower the leading edge till it touches the leading edge of the lower strake.  Lower the back of the strake into place. Drill and Cloeco the front edge of the strake in the non fuel tank section. Duct tape the leading edge of the rest of the strake. Gently place a beam across the trailing edge of the strake from the fuselage to the outer edge of the strake along the seam where the strake meets the wing spar. This will keep the strake skin flat where it meets the wing and help seal the strake.

With your finger fill and smooth a bead along the outer edge of the Bulkhead flange from inside the fuselage, strake tip and rear bulkhead and cover with peel ply. Attach the strake to the fuselage by filling the seam with micro glass and applying 2 bid to the inside and outside of the fuselage and strake seam. Sand the leading edge of the strake and glass with 3 bid.

Attach the the strake to the fuselage. Apply a smooth bead of micro-glass from the fuselage to the strake with your finger. Apply 3 bid of 4" wide fiberglass cloth from stake to the fuselage and across the leading edge of the strake. 

Bulkhead Seal

The top of the bulkhead all the way around the fuel tank must be reinforced and sealed from the outside.This includes areas between the wing strut and rear bulkhead, the strake tip and the cargo area in the fuselage.

Sand the mating surfaces behind the rear bulkhead from the access holes in the tip of the strake and inside the fuselage. Sand the outside strake bulkhead and the outside of the fuselage bulkhead. Clean the areas. Fill in the uneven seams with micro and apply 2 bid fiberglass cloth. For the rear bulkhead long skinny arms or a yard stick with a rounded end may be necessary. Finish with peel ply.

Fuel Caps                   

Place the upper skin on top of the strake and mark the locations of the baffles and bulk heads. Center the cap at a  location past the prop arc inbetween the baffles and bulkhead. Remove the upper strake. measure the cap outer diameter and the inside flange diameter. With a hole cutter cut a hole the size of the inside diameter just through the outside skin of the strake. Turn the strake over and place the it on top of a peice of wood. From the pilot hole on the inside of the strake drill a hole the size of the outer diameter of the cap just through the inner skin.

Remove the foam strait down from the inside hole to the skin of the upper strake. Sand around the hole and on the inside of the upper strake skin that was uncovered by the removal of the foam and bevel the opening until the capfits in the hole from the bottom side and it is flush with the top skin. Sand the bottom edge and the top of the outer flange of the fuel cap. Duct tape the top and all other areas of the fuel cap that are not to be covered with epoxy. Install the fuel cap with micro-glass and 2 bid fiberglass cloth.  

Strake Windows

An added feature to this aircraft is the strake windows that allow the passage to view the terrain through windows in the strake. Cut a piece of plexi-glass to size. Mark the location of the window inside the baggage area of the strake and trace around the window. Remove the plexi-glass and mark a line 1/4" inside the traced line. Drill a 3/8" hole inside the for corners of the inside line.

Chalk line the window opening from each hole on the outside of the lower strake. Cut the window hole out from the outside of the lower strake. Cut the outside line for the window on the inside of the strake. Remove the foam and sand the areas around this frame. Sand the edges of the plexi-glass in 1/4". Duct tape the plexi-glass on both sides leaving the sanded edge exposed. Glass the window in place with micro-balloon. Place a weight on the window to conform to the shape of the strake while the epoxy cures.

Access Holes are needed to allow bolts to be placed in mounting holes and bolted in. These holes are cut in the bottom of the strake in line with the wing bolt access holes. Mark the location of each access hole. These holes need to be infront of the strake beam. Cut a 5" hole through just the outer skin of strake. Cut a 4" hole just through the inner skin of this same hole. This creates a 1" flange on the inside of the strake. Repeat for the other strake. Drill mounting holes through the outer edge ouf the cap through to the flange. Install the nutplates on the top of the inner skin. Punch out the access hole cap. Seal the foam on the cap and flange with micro-glass.