Elevator torque tubes

I ordered my elevator torque tubes from the Cozy Girls. Very happy with the quality. But I wish I would have done a little more homework here. Since I ordered the torque tube offsets (see the Overview section for an explanation), I should have ordered two right side elevator torque tubes and a center spool. I spoke to the Cozy Girls about this before placing the order, but they thought I would be able to cut the left elevator torque tube (just before it penetrates the left fuselage sidewall) and use the leftover as my center spool. However, doing this would mean the center spool would have one of the NC2 notches in it - not ok in my book.

Any who, I decided to move forward as I can cut the left torque tube to size and order a center spool from the Cozy Girls later on.

Here is a shot of the NC2 notch...

Checking NC2 fit with a machinist ruler... perfectly flush!

Notice how the NC2 has the piano hinge hole off-center... in other words, it is very important to install all NC2's in the same orientation so that the piano hinge holes coincide...

I also ordered my NC-7 elevator jigs from the Cozy Girls... I should have purchased two sets so that I could bond both left and right elevator cores to their torque tubes at the same time. So I used the ones I had to make another set.

But before I could bond the cores to the tubes, I had to install the NC2 inserts. I started out by marking the middle of the notch..

Using calibers, I aligned it with the mark, and used it to mark the under side of the torque tube...

Using a #30 drill bit, I drilled the torque tube per plans..

I then refitted the NC2 insert...

And match drilled it...

Before permanently installing the inserts, I applied grease into the piano hinge holes as indicated in the plans.. this is to keep epoxy out of the holes while doing the upcoming glass layups...

Let's talk pop rivets... the plans say to use "BSP-43" rivets. Aircraft Spruce has BSPS-43 or BSPQ-43 rivets. First letter is rivet material (B=5056 aluminum), second letter is mandrel type (S = steel), third letter is head style (P = protruding)... so what's the difference between the forth letter "S" vs "Q".. Q rivets offer greater shear strength and 100% mandrel retention (this means a portion of the mandrel stays inside the rivet). So I went with Q.

Notice part of the mandrel protruding out a bit. I was afraid this would later cause issues when installed them onto the foam cores, but it wasn't an issue at all.

I then installed the NC7 jigs onto the NC2 slots with the NC8 stainless hinge pin.

Next step was to file the middle slot in the notch.. I used the dremel to remove most of it..

And a metel file to fine trim tune it..

Now we are in business!!!

Next step is to seal the edges of the NC2 inserts with "Hot stuff" crazy glue. This is to prevent epoxy from getting down into the piano hinge holes inside NC2. There are 3 different types of "Hot Stuff" crazy glue:

Original (thin viscosity)
Super T (medium viscosity)
Special T (thick viscosity)

Plans say to go with "Super T".. so that's what I used...

I should note here that the torque tubes should be taken to the canard, align the NC2 inserts with the hard points bedded in the canard, and trim the outboard end of the elevator torque tube such that they have 0.1" clearance from what till be the canard tip (0.1" inboard of the canard end).

Let's talk elevator cores... I purchased mine from Eureka CNC and they are PERFECT!!!

I used a hook blade to trim a bit off the bottom edge so that the torque tube would "pop in"..

Lightly sanded it smooth..

Once I was happy with being able to pop the torque tube in, I prepped for bonding. I placed cling wrap on the table to keep it from bonding to it.

Mixed up slurry and painted it on the tube core mating surface... and inside the core channel..

Popped the tube in... cleaned up the excess.. and weighed everything down to make sure the torque tubes would cure in the correct orientation (which the NC7 jigs assure they will). I should also note that the tubes were aligned flush with the elevators' outboard ends. The elevator inboard ends get trimmed later on (when they get mounted to the canard and I have a better idea as to where they should be trimmed with respect to the fuselage walls).

Next up: elevator layup time!!


Anonymous said...

Hello Ary,

Elevator build looks good. Any way to tell what the "latest" is on your site?


Ary said...

Thanks Barry!

If you scroll all the way to the bottom on the main page (www.aryjglantz.com), you'll see I add the date the blog was last updated and I try to put "coming soon" next to items I'm currently working on. I also try to post weekly updates on the facebook page (www.facebook.com/groups/749118165124329)

Anonymous said...

Thanks for the reply. Yep, saw the dates, just wasn't sure what the newest is. I'm not on facebook...

I'll figure it out.