Ken's Sonex 1243

[DCASonex]

If memory serves correct, the problem of cadmium and titanium only occurs at high temperatures. After several failures of the 1/4" stainless bolts, Info from Sonex was to just use the standard aircraft grade cad plated bolts.

David A.

[Sonex1243]

Thanks for the clarification everyone, reviewed the plans sheet again and they do say at elevated temps.

Getting ready to move on to the engine mount install. I can see right away there will be some trimming of the lower attach fittings needed as also noted by other builders. Does the plans reference about the "nominal .060 thick shim" referring to that being roughly what it would take in shim thickness at the 4 corners for a good fit in the mount fittings?

Since the mount isn't installed yet, I am thinking about mounting the axle assemblies on the Ti rods first and then set the toe in / gear leg length when I install the legs into the mount using the mount as a guide to locate those bolt holes. Any thing I might be missing doing it that way?

[Area 51%]

Straight from the for-what-it's-worth department.....It was necessary for me to drill my gear legs as you describe since I have Tracy O'Brian legs and axles. The axle supports come welded to the legs from the factory. The engine mount makes a wonderful drill guide. Just don't break a drill off up in there.

As far as the shims go....depending on the alignment of the mount, you might end up with 030 on one side and 090 on the other (or some other combination). What's more, the shims may have to be tapered if the mount isn't perfectly parallel with the airframe tabs (A good time to commit a crime because you won't have any finger-prints left after tapering a 060 piece of aluminum).

[Sonex1243]

I wasn't quite ready to finish the engine mount fitting, so I finished drilling the gear legs and fit the axles with success this time. I will install them after the mount is fitted and use the mount to start the holes on those ends. I used the drill guide and cordless drill, lots of time and cutting oil. Transferred the 1/8" pilot hole from the axle to the Ti and then mounted it in the drill guide. Used the 3/16" and 1/4" bit and bushings for nice tight hole. Then slipped the axle back on and back drilled the back side using the Ti rod as a drill bushing.

My replacement tail wheel pivot shipped today, I hope to redeem myself on that one.







I won't claim victory on the Ti until the drilling is done!

[Sonex1243]

Replaced the AN4C hardware on the gear axles with the AN4 steel bolts and hardware.

Resuming with the engine mount, I took some more material off the lower mount fittings and have it pretty close after cleaning it all up.


A little more needed.


Looks like the bottom left mount / weld area was still hitting the fitting. It is pulled slightly away for the close-up. The gear leg outlet is still below the bottom fuse skin. I believe a little more to clear the mount welds and mount corner will give me the dimension needed as well as the edge distance for the attach bolt in that lower corner.

[Sonex1243]

Finally got back into the engine mount after a few other distractions like drilling a new Ti rod and lots of sanding down the inside of the new tail wheel pivot with a rod and sandpaper in the drill press to fit the new rod.

I removed some more material from the lower mounts and have it pretty close. Fabricated shims and now have .063 and .025 in all four corners. Clamped everything up with the gear leg cutout flush with the bottom skin. Still need to verify the other dimensions before transferring pilot holes into the shims and mount.

I am starting to struggle with how to verify the measurements per the plans with some kind of measuring contraption and squares. Good point to ponder on how to do it before messing something up! The fuselage is upside down and leveled to start with.




Lower left mount clamped and shimmed


Upper right mount clamped and shimmed

Happy holidays everyone!

[Bryan Cotton]

Ken,
Shoot me an email and I'll reply with some alignment pictures. I have to find them on my PC as that was a few years ago. My Gmail address is my first name and last name and serial number jammed together.

[Sonex1243]

So, after a fall injury due to an icy aircraft ramp at work and ensuing rotator cup surgery healing, I am back!!!!

Thanks to Brian's help with the engine mount rigging suggestions, I got it in place. I'll need to redo the lower shims as i tapered the back edges and am concerned about the edge distance once the mount holes are upsized for bolting. Current stack up is a .063 and .025 in all four corners.


Mount alignment contraption


Pretty close on all 4 pins


Back of shims that were erroneously tapered

[Bryan Cotton]

A thing of beauty! Well done.

[sonex1566]

Hello Ken,
We all seem to go through so much worry and effort with our various degrees of OCD ishness to get the engine and airframe alignment as perfect as possible. I'd love a brave 'Myth Busters' approach to go in the opposite direction to find out just how wrong you can build and it still fly all right. I'm know I'm gonna be sent straight to hell for suggesting poor workmanship, but I'm one of those annoying fools who always asks 'why'. Maybe to settle a bar room bet John Monnet will let me loose with one of his UAV's to experiment with! (Please don't, I'm only joking).