harleym
Aug 13, 2008, 11:07 PM
The title’s an oxymoron since scratch-built Genie fuses are essentially made of wood. However, completed with resin & glass cloth they get slippery. Resin soaks into the wood to create a hard skin, torsional rigidity, overall strength & durability. Fine sanding of the final, overall thin coat of resin on the glass makes for a beautiful painted finish.
As to the droop snoot, bowed boom profile, I’ve used for over 20 years, I liked the distinctive looks, but in addition the nose hits first without spearing & spares servo gears if flaps are down. However, the huge, unobvious advantage is the 30% overall reduction in airframe drag. I didn’t understand why my droop snoot ships were so quiet. The aerodynamic reasons are explained at http://www.nesail.com/detail.php?productID=69.
The Pike Perfect fuse is another notable exception to the straight stick ones used on most contemporary designs. Friend Doug Coleman (dougalert) who has the Pike & a Smooth Genie Pro says the profiles are essentially identical.
Const. File 1 at http://www.geniebuild.com/harleys_genie.html is the primary fuse file. The pics below will help envision how parts go together without the step by step reading.
Please review a paragraph & then the related pic in the attached group below.
Pic 1: The pronounced droop snoot, bowed boom profile is seen. This & a sturdy tail skid keep flaps off the ground, sparing servo gears & pin sockets in cases. With plywood doubler/CF reinforcement by the fin, fuse cross section can be very small, but extremely strong. Light 5/16” balsa fin, a light, low stab & the dorsal minimize stress in that area.
Pic #2: Fuse front end commonly leads to assumption it’s molded. Note how fuse & canopy lines merge. 1/8” aluminum tooth is removable. Tow hook is made from steel “screw L”. Built-in tow block of ply laminations has well-secured internal & external parts. Flared wing saddle gives broad support for the wing.
Pic 3: File 1 tells how to make the displayed Smooth Genie Pro parts. Nose block can accept 2-3 oz. of shot/resin mix. 1/16” ply fuse slab sides are internally spliced with 1/32” ply. On the SGP, these are notched to make room for the side plates that hold the tapped aluminum piece the main wing bolt threads into. See end of File 1 for wing holddown details. After adding the external 1/16” ply doublers over CF laminate, the 1/8” balsa external doublers are attached & then the external 1/16” balsa trippler. Front former is fitted with servo mounting rails & triangular stock (TS) & then glued to the right side. Rear former is next glued in place. A right side “deep rail” capped with ply is glued forward of the rear former. Note the pre-drilled internal & external parts of the tow hook blocking.
Pic 4: Along the inside edges of both sides TS has been added before joining the left side to the formers. On the left side, TS is omitted near the formers, but filled in after joining. Bottom right, a deep rail is shown, but is not glued in until the rear former is attached to the left side.
Pic 5: To join left side to formers, sides up front are butted to a common carpenter’s square. Steel block, etc. keeps things upright. See File 1 for view from the left side.
Pic 6: After sides are joined, simple tool at bottom gets them aligned & straight behind rear former. Bits of 1/64” ply initially hold the position. Then top behind the rear former is fully sub-decked with it. Then the CF stab pushrod tube can be installed.This is followed by the bottom sub-decking & nose block installation, completing a skinny ply box with a nose block.
Pic 7: Thicker balsa is added to the skinny box for shaping with razor plane, tiny Stanley Finishing Plane, etc. & sanding tools. Fin, with bellcrank installed & pushrod attached is slipped between the sides & secured with instant CA glue. See separate File 4 about merging canopy & fuselage. See separate file about Glassing & Painting.
The construction technique can be used on most any saddle mounted wing design. Just adapt it to the airframe size, desired fuse shape & airfoil, etc.
As to the droop snoot, bowed boom profile, I’ve used for over 20 years, I liked the distinctive looks, but in addition the nose hits first without spearing & spares servo gears if flaps are down. However, the huge, unobvious advantage is the 30% overall reduction in airframe drag. I didn’t understand why my droop snoot ships were so quiet. The aerodynamic reasons are explained at http://www.nesail.com/detail.php?productID=69.
The Pike Perfect fuse is another notable exception to the straight stick ones used on most contemporary designs. Friend Doug Coleman (dougalert) who has the Pike & a Smooth Genie Pro says the profiles are essentially identical.
Const. File 1 at http://www.geniebuild.com/harleys_genie.html is the primary fuse file. The pics below will help envision how parts go together without the step by step reading.
Please review a paragraph & then the related pic in the attached group below.
Pic 1: The pronounced droop snoot, bowed boom profile is seen. This & a sturdy tail skid keep flaps off the ground, sparing servo gears & pin sockets in cases. With plywood doubler/CF reinforcement by the fin, fuse cross section can be very small, but extremely strong. Light 5/16” balsa fin, a light, low stab & the dorsal minimize stress in that area.
Pic #2: Fuse front end commonly leads to assumption it’s molded. Note how fuse & canopy lines merge. 1/8” aluminum tooth is removable. Tow hook is made from steel “screw L”. Built-in tow block of ply laminations has well-secured internal & external parts. Flared wing saddle gives broad support for the wing.
Pic 3: File 1 tells how to make the displayed Smooth Genie Pro parts. Nose block can accept 2-3 oz. of shot/resin mix. 1/16” ply fuse slab sides are internally spliced with 1/32” ply. On the SGP, these are notched to make room for the side plates that hold the tapped aluminum piece the main wing bolt threads into. See end of File 1 for wing holddown details. After adding the external 1/16” ply doublers over CF laminate, the 1/8” balsa external doublers are attached & then the external 1/16” balsa trippler. Front former is fitted with servo mounting rails & triangular stock (TS) & then glued to the right side. Rear former is next glued in place. A right side “deep rail” capped with ply is glued forward of the rear former. Note the pre-drilled internal & external parts of the tow hook blocking.
Pic 4: Along the inside edges of both sides TS has been added before joining the left side to the formers. On the left side, TS is omitted near the formers, but filled in after joining. Bottom right, a deep rail is shown, but is not glued in until the rear former is attached to the left side.
Pic 5: To join left side to formers, sides up front are butted to a common carpenter’s square. Steel block, etc. keeps things upright. See File 1 for view from the left side.
Pic 6: After sides are joined, simple tool at bottom gets them aligned & straight behind rear former. Bits of 1/64” ply initially hold the position. Then top behind the rear former is fully sub-decked with it. Then the CF stab pushrod tube can be installed.This is followed by the bottom sub-decking & nose block installation, completing a skinny ply box with a nose block.
Pic 7: Thicker balsa is added to the skinny box for shaping with razor plane, tiny Stanley Finishing Plane, etc. & sanding tools. Fin, with bellcrank installed & pushrod attached is slipped between the sides & secured with instant CA glue. See separate File 4 about merging canopy & fuselage. See separate file about Glassing & Painting.
The construction technique can be used on most any saddle mounted wing design. Just adapt it to the airframe size, desired fuse shape & airfoil, etc.