Saturday, November 16, 2013

16-02, Stall Warning Switch

11/13/13:  Here’s another deviation from the strict order of The Book.  I’m building up the stall warning switch so I can install it on the appropriate rib before that rib gets riveted to the spar.

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 In turn, I’m not following the strict order of installing the ribs, either.  I’ve clecoed the nose ribs to the L spar to make sure that I’m putting the correct “L” and “R” ribs in place before committing anything to a rivet.  The stub spar has also been attached to the inboard nose ribs, although not without a comically bad attempt at installing a rib upside down (see page 15-05 for that story.)

By installing the nose ribs first, I can turn the spar over on the sawhorses and avoid putting any side loads on the ribs at all.  I’m very cautious about them, as they are quite flimsy until properly skinned.   While the spar is forward=up, I want to get the stall switch installed, the nose ribs attached and then do the test fit of the lower skin with respect to the stall switch.  I’m hoping that keeping the wing oriented this way will relieve most of the clumsy maneuvering that I anticipate in fitting that skin over the switch.   Once I verify that that the stall switch is in a good position, I’ll flip over the wing and do the main ribs, then the main (lower skins).  With the lower skins in place, the wing will be mechanically much more stable.  Then it goes into the cradle, and I repeat the process with the R wing.

After the main skins are on, but before the upper skins close out the wings, I’ll do the wiring kit.  By that time, it should be Dec 9, at which point I will meet Bob Leffler who is an EAA Tech Counselor.  He’s going to come over to my shop and check out my work.  Although not really required, I want to leave the wings open for him to be able to look around.

I’m still not sure if I want to go EAB or ELSA.  There’s a matter of increased pride in both directions:  by going EAB I can take on the pride of “American independence” and it will be my name on the data plate.  By staying ELSA, there’s the pride of “yes, I can follow directions” and have potentially easier time selling it.  (Do I really care about that?  Not sure....)



It’s been a busy weekend, and I’m posting several pages, so feel free to get confused as you read through this.  Here’s the stall warning switch installed on the rib, prior to being skinned.   Note anything?  Take a look at the orientation of the stall warning vane.  It’s angled up, not down.  Needless to say, I did note and correct that little ‘oops’.  Luckily (or is it skill [no]) I did note this before attempting to put the skin on and thus damage it.  While I was removing / replacing the stall switch assy, I noted that it was very rough to pivot, and would thus be difficult to adjust when the skin was on.  I sanded out the inside of the race that the upper screw uses to permit pivoting and it’s better, although still not smooth.

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At the time of this posting, I have attached (riveted) the outer and inner lower skins, and clecloed the middle skin in place over the stall switch.  It’s not yet adjusted for proper operation.  I’m planning on riveting down the leading edges of the inner and outer skins so they aren’t flapping around and while the wing is right side up, adjusting the switch.   With the access panel on the bottom and the open leading edge on the top, I hope to be able to do this adjustment without needing to remove the skin at all.  

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