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Final Push on the Empennage

May 31, 2011

Here’s a tease.

This is 97% done.

So this weekend I didn’t get as much time on the project as I would have liked.  It was Memorial Day weekend, so we had parties and such to attend all over the place.  But the time I did spend was well spent

I finished rolling the leading edges and as fate would have it I ran out of blind rivets.  I put a note in my “Lessons Learned” pages, but the short version is I must have made more mistakes on previous pieces than I thought.  Do you have any idea how difficult it is to find aviation grade blind rivets in Bentonville Arkansas on Memorial Day weekend?  I did make a few calls and Terry Rhew saved the day with 6 rivets.  Not enough to fly with, but enough to jury rig it until I get more.  I have 3 holes that are missing rivets, but that’ll work for now.

Next came the rod end bearings.  They need to be screwed in and secured with a jam nut.  The depth is 13/16″ and no greater than 7/8″.  The problem with these things is that the tolerances of the threads is very tight, so screwing it in requires some pressure.  Thats why you have to make a tool.

Sorry. Crappy camera is back due to circumstances beyond my control.

You start with bits of PVC pipe and wind up with an incredibly dodgey tool, purpose built and barely capable.  You insert the “eye” end of the rod end bearing into the tool and screw it in.  I’ve seen some sites where guys make this thing out of aluminum, welded and anodized.  I literally made this in 15-minutes and didn’t even glue it.  But to get the bearing the last few turns it does a pretty decent job.

This is an action shot of me using NASA-like tools in a NASA-like fashion

The end result is the rod end bearing being 13/16″ from the base of the spar to the middle of the eye in the bearing.

13/16" on the money

Do that 4 times and you’ve got all the bearings in place.

Next up on the agenda is getting the elevators attached to the HS.  Like a lot of task on the plane, this one requires time, twiddling and tinkering to figure out.  There is no room to get your fingers into the spaces between the elevator and the HS.  You might be able to get one finger in, but that isn’t enough to wiggle the screw in.  I tried big needle nose pliers.  I even started to think about bubble gum on the end of a stick.  While trying to figure it out I came up with a temporary solution, just so I could get the pieces on and check fit.  I bent some brass rod and made up a few “L” shaped gizmos.

Made from 1/8" brass rod.

These worked great.  Easy to make and I could use them by myself.

Here is my makeshift hinge

For the actual bolts I eventually decided to see what other builders did.  While surfing I had an idea that a surgical hemostat type device would get the job done.  This would be perfect because it would hold the bolt, lock in place and be fairly easy to unlock.  A 30-min trip to Harbor Freight (cheapest tools Asia has to offer) and I got what I needed.

Sorry again for the poor quality.

This is what the Dr. ordered (I am so funny).  Anyway, once I had this getting the bolts in was pretty easy.  The end result was this.


Pretty neat!  I have one control surface hung and ready.  The rest was just the same.  Ultimately I wound up with the picture I teased you with at the top.  Both elevators attached and the fit is amazing.  I could not imagine doing this and having to drill the holes myself.

The next task was a challange.  In the center of the rear spar there is a bearing that I made about two months ago.  The next task is to use a “drill bushing” to guide a drill bit in and drill holes that will eventually be the pivot point where the elevators will be controlled.  The drill bushing doesn’t come with the kit and it is only described as a rod with a small diameter hole in it that slides into the bearing.  Much google searching arrived at a company that makes them and sells them for about $10 a piece.  Of course I was going to have to wait and pay shipping, there has to be a better solution.

I decided to go to Lowes and look for bushing material.  I found plenty but none of it was suitable for the task.  After giving up on that I decided I might be able to take a 1/4″ (the OD of the bushing had to be 1/4″) rod and drill a smaller hole through the length.  I eventually came to the conclusion that my drill press, while being quite nice, isn’t going to be up to the task. This left me with one choice.  Wander the isles of Lowes looking at items that might server the purpose.  I wound up in the isles where you find door knobs, rope, mailboxes…etc.  Near the rope are bins that hold all sorts of hardware designed to let you make custom ropes.  In one the bins I found this:

This is soooo thinking outside the box for me

Inside the package I found these little gizmos.

The round gizmos at the top are the future drill guides

I took a pack and went to the hardware section and measured the diameter of the round bits.  1/4″….I cant be this lucky.  I bought 3 packs @ $.98 / pack and headed home.  I whipped out the micrometer and measured.  The hole is .253 inches the little gizmos are .247 inches.  I can’t be this lucky…can I?

You have got to be kidding me.

It fit perfectly!  Like I milled it specifically for this task.  In the picture above I need to insert a drill bit into that tiny hole in the center of the guide (upgraded from gizmo to guide) and drill a hole into the white metal piece (known as the elevator horn).  How did it work?

Now that is a hole. BRB, phone is ringing. I think its NASA.

Second verse, same as the first on the other side.  That was a killer solution.  I might have to post this as a TIP on VAF.

One Comment
  1. This was really helpful — Thanks!!!

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