Skeletons In The Garage

Since my last entry I’ve been doing some flying, and also a bit of building. And yes, I’ve got pictures to show! Here’s me next to a PA-18 Super Cub. I’m working on my tailwheel endorsement in this one at Promark Aviation, and it is a blast! One more session should get my signoff, but weather and schedules have not cooperated in the last month to get that done. Soon. Hopefully!

I also took Liz flying in an Evektor SportStar from Pilot’s Choice. Compared to the Super Cub it’s more comfortable, but I really enjoy the pure “stick and rudder” flying of the Cub. Oh, who am I kidding? They’re all fun! 🙂

Now, on with the build pictures! First, a shot of all the parts I’ve created for the horizontal stabilizer. Not shown are the forward and aft main spars, which I purchased already formed from Zenith. I decided it would be too difficult to form them on my home-made 8ft bending brake, or more correctly the frustration wouldn’t be worth the modest price of the finished parts.

The assembly begins by measuring and marking all the rivet locations for the spar caps, doublers and ribs. This time I paid careful attention to the rivet spacing in relation to the ends of the caps and doublers to avoid any edge distance issues like I encountered on the fin. #40 holes were drilled in the spar first.

The spar caps, doublers, and ribs were then clamped into place and back-drilled through the spar.

Next were the front spar attach brackets:

It’s starting to look like something!

The same basic steps were then repeated on the rear spar and attach brackets.

And like magic, it’s really resembling a stabilizer now.

A concern I had was that since I was making these parts from scratch the specified skin width might not fit properly from spar flange to spar flange (wrapping around the ribs of course). Once I had it cleco’d together, I wrapped the tape measure around it to check. The plans say the skin should be 870mm wide. Guess how far that’ll go on mine? The rib flange needs a bit of a trim, but the alignment on the spar is bang on!

That made me very happy, and gives me a nice boost in confidence knowing it’s coming together just as specified. I now have to disassemble and debur everything, then cut and fit the skin. It’ll probably be a week or two before I have pictures of that, so stay tuned!

As always, you can browse all the photos in my 750 Cruzer album.

Horizontal Stabilizer Begins

As January rolls to a close, February starts with typically strange weather here in Texas. It’s not unusual for one day to be in the 80s, the next day in the 40s. As such, you just never know whether you’ll be working with the garage door open and a t-shirt on, or door closed with heater and a jacket! As you might expect, my time in the workshop has been rather sporadic! Sometimes it’s better to be out in the yard doing a deck project instead of in the workshop on a pretty day. 🙂

Despite that, I’ve managed to make a bit more progress. In the blog entry titled End of Year Start of Assembly I had a few photos of the horizontal stabilizer rib blanks and form blocks. This entry will show the completion of those ribs, as well as the horizontal stabilizer spar caps and doublers. First the ribs. Here’s one of the blanks clamped in the form block, with the flutes already started.

And here it is after coming out of the forming process.

Repeat a few more times, and you end up with this.

Some of these ribs need “joggles” formed into the fore and aft flanges, to allow them to sit flush over the spar caps and doublers. There are various ways you can form these joggles, but I decided to try using a couple of simple tools that I use to help straighten my rib flanges. By positioning one block inside and another outside, a quick tap of the hammer sets the joggle. Here you see the blocks in place.

And the rib after tapping the wood block with the hammer.

It is a quick and simple way to make the joggles, especially in these .016″ ribs. It might be a bit more difficult, or take more taps, in thicker material. The other end of the ribs get double joggles:

Moving along, the tip ribs are simple straight-sided parts that can be easily formed on the brake.

You can see from the plans page those parts are sitting on, that there are several spar caps and doublers to be formed as well. While I purchased the spars from Zenith, I decided to bend the caps and doublers myself. In hindsight, I probably should have purchased the spar caps because bending small “L” type angles from .040″ 6061-T6 is a cast iron… umm…. female dog. If you get my drift. 🙂 However, they are done and they turned out pretty well.

That’s it for now! I have received my order of more aluminum sheet, so I can make the rest of the stabilizer ribs and continue with the attach brackets and other parts. Once those are done I can start the skeleton assembly. I probably won’t update the blog again until I have some drilled parts to show, so it may be a few weeks. Don’t go away!

As always, you can browse all the photos in my 750 Cruzer album.