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repair4 - Wing Mounts and Landing Gear Support Renovation

Repair 3

Above photograph shows ply landing support sliced for removal. Black tube support of carbon fiber (CF) rod shown cut on both sides; First layer of thin plywood not shown - already removed.
 Base ply is gradually being removed with circular carbon cutter.
  New composite fuse rings and landing gear floor support design currently in evaluation.   

View of a Wing tip in preparation for internal structure reinforcement, composite wrap build up and interface to fuse. This wing tip adds 1 foot to one side of the complete wing.

Tourists or lost?
You decide.

Fiberglass-Epoxy Wrap

Floor plywood internal landing gear brace shown in above photo removed; also cut out is glue adjacent to LiPo section.
Note: some cuts passed through carbon fiber which was wrapped over fuse - to be repaired.
 
This wing and landing gear support section is being rebuilt to withstand greater forces and integrate an interchangeable wing into fuse.
 

  Placement of FR-4 board for sizing of landing strut mount - this new platform requires accurate measurement, alignment and integration to fuse.
   Model of internal structure to support wings now being fitted. 
   Internal structure being fitted to handle about a kip (1,000 lbs.) of bending stress from each wing.

Pizza Box Molding

   Fiberglass wrap over fuse using epoxy: Prior to cure at room temperature, this multilayer blanket is form a multilayer FG base over which either plaster, clay or bondo will be added.

   Basically, this is a tool to build up a surface, then finish that surface. This composition is placed over a 6 mil (thousands of an inch) thick mylar barrier to protect the fuse surface.  So, why do this? 

   A replacement of the existing cut away of the original was necessary to withstand 20 gs meshed to a modified fuse.

  Experimenting with gorilla glue as a mold making tool: wax paper base to keep water off inside. Cardboard is wet thoroughly, then peeled apart.  Gorilla glue is brushed on layer by layer and spread.  Then, strong tape is wrapped around the part.
   While initial 2 to 4 hours pass to obtain 80 percent strength, the tape wrap remains. Mineral spirits were unable to dissolve glue; hence wasted brush.
   Gravity pulls water down, so cardboard around lowest part remains wet for much longer in time. Hair dryer speeds drying as does carefully removing the cardboard paper shell. 
 
   Foam spray insulation (urethane) - provided a non-tacky layer can be set up - may provide an another alternative mold technique to a fiberglass layering. 

See Wings.asp page for information on the composite wing in progress.

Approximate Location of metal sleeves

  Two ounces of 1/2 inch steel conduit cut of 1 inch sections for wing to fuse root.  Each completed sleeve with CF tube layers designed to handle 1 kip dynamic load each. Slit cut along length to fit CF tube for epoxy grip. Steel tube stem slides into fuse to mount wings. 

  Circular tube forms are effective inhibiting twist or strong dealing with torsion per unit weight. Carbon fiber provides stiffness, tensile strength; adding a steel sleeve over the CF tube toughens the composite enabling much greater shear blockage in a small space. Carbon fiber is weak against lateral hits; this adds armor to CF.
   This CF tube is further integrated into the wing via internal reinforcements to further enhance the rigidity of the wing across the wing length. 

   An I beam is also a useful solution to maintaining a rigid wing shape.  Also, a rectangle box tube is another approach of practical application inside a wing.  Each method has its application in the context of the overall wing structure design and related materials.  

   Reasons for the metal sleeves: distribute forces over larger area; inhibit shear forces from cutting carbon fiber tube wing stem, increase compression strength; align wings to fuse; inhibit fracture of carbon fiber and protect aircraft from sudden impacts.

     Note: location of wing interface is determined by expected loading and moment forces; weight and balance of aircraft requires careful consideration to maintain efficient flight characteristics.

     Inside the fuselage, the steel sleeve will be jacketed by carbon fiber tow; this tow epoxy bonded to fuse structure. Clay is used to make a template to form an additional CF fuse ring at the LiPo wall.
 
    

   Some approaches use the wing skin to deal with wing twist forces and the underlying structure to boost wing stiffness.  Structural fiberglass over foam has tensile strength. To obtain stiffness in the wing a thin pliable foam is added in a layer inside the composite vacuum form with an epoxy binding.
 
   Internal ribs and lateral stringer is further epoxy bound to the stiff wing skin yielding a hybrid lightweight structure.

     Aircraft Construction: Plastic light, steel strong.

Repair 5

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