Rudder Cable Guides (Feb. 28th, 2002)

The 500 mm x 500 mm Nylcast plate is ten times more of material than I actually need for the pivot blocks. So the rudder cable guides will be another application. Here is a sketch:

The guide consists of two staggered symmetrical parts. The guide can be installed without disconnecting the control cable. The friction is less than Wick's Nylon guids.

One problem with the Nylcast is its thoughness. It's really hard to cut the stuff at the bandsaw. I'll try a circular saw for the next cuts.

If this parts work out O.K, then I probably substitute also the 'oillite' bronze bearings with hommade Nylcast bearings.

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Pivot (and other) Blocks (Feb. 26th, 2002)

Pivot blocks serve as 'bearings' for the rudder pedal tubes, flap torque tube and other moving parts. Per the plans these pivot blocks are to be made from 'Phenolic' bar stock.

here are some reasons why I don't like the phenolic stuff:

 

So I had to look around for something better. And this is what I found:

*** NYLCAST(R) ***

This is cast nylon which got oil embedded into the macro-molecule structure. Advantages are:

 

Here are some specification numbers:

 density  1.13 - 1.14  g/cm3
 rel. water absorption  < 4  %
 tension strength  720 to 900 kp/cm2
 bend strength  770 to 1270 kp/mm2
 elasticity modulo

 21000 to

28 000

  kp/cm2
 Shore hardness  80 - 85  
 friction coefficient  0.13 - 0.14  
 temperature resistance, short time  -40 to +145  deg. C.
 temperature resistance, unlimited time  -40 to 125  deg. C.
 melting point  220 to 225  deg. C.
 burn characteristics  self extinguishing  
 internal lubrication  liquid, oil  
 specific electric resistance  > 10e12  ohm/cm
 colour  black  

 

I received a 500mm x 500mm x 20mm plate from Farnell Components today. I'll roughly cut the pieces out using the bandsaw and then make use of the company's machine shop for final processing.

 

Probably there are some more applications for this material. Why, for example, make the rudder stop plates from heavy aluminum? Another application which comes to mind is the substitution of these cheap plastic 'snap-in' bushings of the push-pull tube guides.

 

I'll report when the first pieces are done.

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Woodwork (Feb. 23th, 2002)

This is the core section of a plum tree trunk which I had to fell this winter.

It's got a beautiful brown/dark-red grain pattern. This will become the stick grips. When the wood is dry (in a year or so...) I'll take a clay pattern of my right hand and then carve two first-class stick grips.

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Vertical Tail, shining brightly (Feb. 19th, 2002)

The result after two nights of hard polishing. The assembly is waiting now for warmer spring temperatures. Then the internal structure will be primed and then the skin riveted on. At least at one side I'll use solid-flush rivets. The other side probably flush blind, depending on how deep I can reach inside with the bucket bar.

 

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Vertical Tail, Second Round (Feb. 13th, 2002)

I have changed mind. A ~new~ part will be made.

This is the bad piece, exactly made to the plans (SNX T10-02). You can see the 45 degrees edge and the hole position I scribbled into the plan for my new part.

 

 

 

 

 

 

 

 

After 2 hours of bending, filing and sanding the new channel was done.

The new (upper) part allows now for proper 6.2mm edge distance. The 45 degrees edge interfered with the trailing edge's spar flange so I rounded it off.

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The Vertical Tail (Feb. 11th, 2002)

Skinning the vertical tail was easier than expected

 

This time the pilot-drilled skin almost everywhere met the internal U-channel's flanges as planned.

 

I said ~almost~

I don't know why this last rivet hole violates the edge distance rule (and I'm too tired now to find out). This will repaired, no new part this time. I'll flush-rivet a strip of alum underneath. That should do the trick.