28 May 2016 - More Trim Servo Work

Wanted to take the tailplane off today for storage and remove the elevator from it. When I came to threading my new connector out I discovered the hole was too small in the trim tab so had to take all the pins out to remove it.

After measuring the diagonal I decided to open out the hole. Some have made a separate hole to avoid having the jack screw sharing the hole and coming close to the cable. If I use the same hole as is standard, having a bigger hole can only help.

I found my 3/4"step drill bit would just fit through the slot in the leading edge of the trim tab and having a hex shank I could extend it.

Deburring the hole was more of a challenge. Here is a pic of the servo jack screw and the servo cable sharing the enlarged hole.

I have become an expert a removing the Sero assembly from the trim tab now. The big tip is you must fully wind the servo jack screw into the servo before disconnecting it. Fully in = fully down on the trim tab. Then you have the problem of an elevator with a trim tab in the fully down position if you want to store it. I made a 6 pin mini fit Jr extension lead that I put on to enable me to straighten it up after putting the servo back in for storage.

Back to the Aileron servos. Instructions call out for Safety wire for the linkage to the springs. I am not too keen on this and may re-make later using RC servo linkages and piano wire (as others have done), when I aquire the parts so for now a trial run with undersize wire to help me decide.

But for now I followed instructions but added heat shrink.

• With the stick central set the servo central over the center pitch crank bar.
• Everything is symmetrical so linkages should be the same length.
• You need to choose a length that so the springs never go slack on one side and start flapping about with full side sick applied.
• I found 8cm seemed about right for both sides.
• Made my first wrap for the spring side 3cm long and heat shrinked
• Slid other sides heat shrink on
• Measured and formed a bend at 8.5 cm (0.5cm taken up in twisting)
• With wrap removed from spring threaded wire linkage onto servo tab and twisted it
• slide heat shrink up and heat shrinked second end.
• Mate wire link with spring
• Repeat for other side.

Everything Central

Central servo with full left stick

Central servo with full right stick

When I get the correct size locking wire or RC servo linkages I will take a look at the unlikely event of full left trim full right stick later when I have aileron limits fixed as I don't want to over extend my springs.

Here is a video clip of the effect of applying trim full each way. Rather shaky as I am using a phone and operating the SkyView at the same time:

Next I want to finalise wiring for the tail light I havent got. I am running a strobe and a Nav
 Position light to the rudder bottom position.

It is interesting that there are precise light angles specified for the light which means you cant use any old light but then you mount it on a moving part! Seems like we ar paying alot of money for aircraft spec parts for no good reason here.

To measure and mark things off with the tail and on with The Fin and Rudder

You cant fit the bottom fiberglass rudder fairing to the rudder with the rudder fitted so of and on again.

Need to find a spot for the wire penetration. Some have brought them out just above the faring so need to mark up that spot.

It is a bit close to top of hinge bracket, I may cut some meat off the fiberglass and drop it a little.

Some builders have made a hole much lower down and made another slot in the fiberglass for the wire. I will sleep on that decision.