Thursday, July 1, 2010

How to make a Carbon Fiber elevator which weighs less than 3 pounds!

I am planning to give a forum at OSHKOSH on how to make a Carbon Fiber elevator.  PLEASE PLAN TO ATTEND!  Thanks.

The Carbon Fiber elevator which is depicted here WEIGHS LESS THAN 3 POUNDS!  And it is stronger than steel.

Carbon Fiber offers benefits which make it vastly superior to 4130 chromalloy steel in many applications.  Careful design is required, though, in order to take advantage of Carbon Fiber's incredible strength and stiffness.  Belite's Carbon Fiber elevator upgrade swap is an available upgrade for any Belite (or Kitfox Lite replacement aftermarket) which will provide a lighter part with far higher strength and better aerodynamics.  This part is available in kit form for a price of $350 over the regular elevator.  (You can find it on our kit pricing spreadsheet here as line item #55.  Remember, this is an upgrade price over the steel elevator (which is separately priced at $399.95).  A straight purchase of this Carbon Fiber elevator kit is $399.95 + $350 = $749.95)

Our Carbon Fiber elevator is a direct replacement for the steel part.  It is made from several basic materials:

Carbon Fiber fabric wound tubing (for leading edge / torque spar)
Carbon Fiber extruded tubing (for trailing edge)
Steel horizontal stabilizer connect hardware (qty 2 -- connects to hinge points on horizontal stabilizer)
Central Steel section (connects to hinge point and to elevator push/pull tube)
Carbon Fiber ribs in various laminations from 3 to 6 layers of carbon fiber 3K cloth, over balsa core
3M 2216 industrial epoxy (amazing stuff)
Laminating epoxy
Dacron Fabric

Jumping to the finished part, here is what it looks like:

And here is how to make it:

1)  Ensure Carbon Fiber spar tube is exactly 92 inches long.  Cut with fine tooth saw to length.

2)  Debur, clean and slide the center steel assembly over the spar tube.  Epoxy in place with 2216 glue.

3)  Debur, clean and slide each hinge point over the tube.  Do not epoxy. 

4)  Cut each rib section using a band saw and supplied rib outline.  Cut front circle to match spar tube.  Leave rear portion extra long, excess length will be trimmed.  Carefully cut angle cuts on center ribs; also cut reinforcement segments. 

5)  Cut wingtip ribs and center ribs to exact length. 

6)  Cut trailing edges to length; you may leave them slightly long.

7)  Glue wingtip ribs and center ribs in place to main spar and trailing edges using 2216 glue.  At this point, you have a complete outline of the elevator.  Allow to fully cure (24 hours) before proceeding.  It is helpful to wrap around carbon fiber tube and ribs with masking tape.  This will force glue to exact shape and is easy to pull masking tape off after curing.

8)  It is now easy to continue fitting each rib to exact length requirement.

9)  Glue all ribs in place using 2216 glue.  Glue remaining hinge points in place.  Allow to fully cure (24 hours) before proceeding.

10)  Now all ribs are in place.  Sand excess 2216 off.  DO NOT sand into any Carbon Fiber.

11)  Reinforce all joints using carbon fiber cloth and conventional laminating epoxy.  This is easily done by laying the carbon fiber strip over the edge, with the elevator vertical, and painting on the epoxy.  It is helpful to do the leading edge, allow to cure, then flip the elevator and do the trailing edge.

12)  Trim excess cloth using either a dremel or a sharp razor blade.  If you use a razor blade, it is helpful to do it prior to full cure of the epoxy.

13)  Sand all Carbon Fiber cloth.  Remove every single sharp point.

14)  Cover using Stewart Systems glue and dacron fabric.

Here's the advantages:

a)  thicker profile allows aerodynamic shape
b)  lower weight, of course
c)  stronger
d)  impervious to rusting
e)  It's just plane cool!  Or is it plain cool?!

Here's some more detail pics.  Our kit includes plans and more assembly info.....

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