Tag Archives: jigs

Aviation

Another GREAT shop day

Two great shop days in a row, how awesome is that?

Another five hours today; that makes ten hours for the weekend. A fantastic way to wrap things up for the week, I think.

I started out the day by sanding the stern post core and preparing it for bonding the ⅛” skins to it. The T-88 did a great job bonding the edges of the core pieces together, and waxed paper works fantastic as a barrier and release paper. I hadn’t worked with T-88 before so this was a trial run for me. T-88 measures out and mixes up easily. The change from two components, clear and honey, mixing to a cream color when stirred together makes it really easy to tell when it is thoroughly mixed. The best part is the smell, or lack there of. I have been doing some work with polyester resins in my day job, and that stuff is really noxious. The T-88 is so easy to work with and so far I am really happy with its performance.

With the stern post core bonding to the skins and clamped up, it was time to move on to the firewall. First I had to remove the strengtheners from the original firewall which took a little longer than I had hoped for. Once all of the hardware was removed and the strengtheners separated it was time to mark out the new firewall. After marking out the cut lines I set up the table saw and did the rip and cross cut for the basic shape. The new firewall matched up perfectly with the old one.

I decided to clamp them together and used the old firewall as a drilling jig for the new firewall which worked out very well. The holes are really snug on the bolts so any misalignment would make life difficult at this point. Fortunately everything lined up spot on and bolted up cleanly. The counter-sink worked much better this time around. With everything torqued up, the bolt heads are just a couple of thousandths below the surface and they look great.

   

   

With the shape cut and the strengtheners attached I started setting up some test boards for the bevels. Both side edges of the firewall have an 8.5º bevel and the top has a 5º bevel. I was concerned about the set up and I wanted to make sure I didn’t hose the second firewall. After a few sample passes through the table saw I had the angle and distance from the fence set up just right. Time for the bevel cuts.

   

After the bevels where cut it was time to cut the parallel notches in the bottom for the firewall that will eventually accommodate the longerons. There are still several things to do on the firewall but it is well under way.

   

If next weekend comes even remotely close to this weekend in productivity I should be able to finish the firewall and maybe even get a good head start on the stern post, at least get the rough blank cut for the stern post. Looks like I need to get my ducks in a row as far as materials go for the spar bulkheads.

Until next time, blue skies and tail winds.
~FlyBoyJon

Aviation

Airfoils

Airfoil RibsThe last few days have been a bit of a blur. I am shaking off the last remnants of a frustrating head cold that lingered for way too long. This week was also the first week of an early class at SJCC before my spring semester classes begin on the 31st. With the cold and classes I haven’t gotten much of anything done at the day job and getting into the workshop was near impossible.

As a consolation, I managed to get in a bunch of pseudo-shop time in by working on the airfoil templates. All totaled up I put in 11 hours marking up the templates on contractor’s paper and cutting out the finished templates. It is surprising how much time can be spent on laying out even the smallest airfoil. Over 30 measurements are used to lay out the basic shape, and you still have to round everything out for a smooth form. Science and art in one operation.

The picture above shows all seven of the airfoils laid out on the kitchen floor. On top is the wing with its 58″ chord. Below the wing is the stabilator, and below the stabilator are the five airfoils that are stacked to form the rudder. There will be 30 copies of the wing rib, 8 of the stabilator and only on each of the rudder ribs. There are a total of five variations of wing rib and two variations for the stabilator, but they are all based of the basic forms. I will post more about the jig and duplication process when I get back to the airfoils. For now, since I am feeling much better, I move back to the bulkhead construction portion of the project.

This last week’s diversion to the airfoils is a good example of building flexibility into your project schedule so you are able to take advantage of available time when life strikes.

Until next time, blue skies and tail winds.
~FlyBoyJon