dle's Oz Build

[David47]

I think I can see how difficult it would be trying install nuts on those hinge bolts without the +/- 25 Deg rudder movement. I reckon I've got no more than 5 Deg movement either way right now without cutting the stop, so its only possible to install the bolts unless there's a seriously large lateral slot cut into the LE fairing on the rudder. Defeats the purpose of trying to minimise gaps to stop aero leakage .... thanks for the input.

[David47]

Slower weekend this time around. I had the first visit from my Sports Aircraft Association of Australia (SAAA) Technical Counsellor this weekend. The SAAA are responsible for oversighting build projects that will be registered with a VH- registration (equivalent to "N" Reg in USA) which will allow me to flight test and then fly up to the maximum AUW of 1550 lb under an Experimental Certificate issued by the Australian regulator. The visit was all good some plough on.

Spent quite a bit of time applying the two coats of varnish to the ribs in the empennage. Did that over three days. I needed to not load up the brush so much because this stuff runs all over the place. From other threads, others seem to have had similar experiences. I've got varnish drips hanging off the vertical fin tubes like icicles so a clean up is required.

Installed the parking brake valve assembly to the console temporarily. As an observation, installing the 90 Deg elbows permanently could be interesting because the ports are so close together that the elbows obstruct each other when you turn them to thread them in.

I also sanded the stabiliser bearings down so that they run freely in the hinge bushes with bearing grease. I took up the construction manual suggestion of chucking them in the hand drill and used 120 grit, followed by 240 grit sandpaper to finish them off. I then attempted a trial fit of the stabiliser to the fuselage but ran into an interference issue. The welded fuselage attach brackets appears to be interfering with the weld at the base of the stabiliser mounted hinge, to the point that I can't quite line up the bolt. I'll most likely have to remove some material from the fuselage bracket as I don't want to start grinding away at the excess weld, especially on such a critical attach point. Anyone else have this same issue ?.

Finally, I bonded foam onto the stabiliser, elevator and rudder tips and started rough contouring using 240 grit sandpaper. It looks rough at the moment (several photos attached showing start and finish except for sealing) but Ill probably use the hysol adhesive to seal the foam. I know others have used other filler materials but I'll stick with an IPA wetted finger and Hysol (thanks Gary and Jim) to do the final finish. Hopefully I can sand that to a final smooth finish ok. I've managed to get a reasonably aerodynamic shape at this stage and should be able to wrap the covering around ok when I get to that stage.

Next week I'm planning on starting to build the wing assembly jig, even though I still have stuff to finish off on the fuselage. I can potter along on the remaining fuselage items in parallel with building the wing. I'm happier multi-tasking ....

The wing assy jig will be made from a steel weldment and I'll try and incorporate converting it to a rotisserie for both the wings and the fuselage for when I start the covering process. And then there's the possible future use as a hanger stand for tyre changes and other off the ground maintenance. At least that's the plan ....

[jiott]

If I am remembering right, don't those stabilizer hinge bushes get pressed in and Locktited in place? The free running part is the bolt thru the center hole I think.

[Esser]

I'm pretty sure that's what he means. He is sanding the bushing that goes inside the press fit bushing. Creates a type of bearing.

Do you have a picture of where you are getting the interference with the fuselage? I did have to modify the stab so I could ream the hinges before I pressed the bushings.

[jrevens]

If I am remembering right, don't those stabilizer hinge bushes get pressed in and Locktited in place? The free running part is the bolt thru the center hole I think.

I had to think about that too. Actually, those are pressed in, then another bushing runs inside of them, clamped to the tabs on the elevator with the bolt. No bearing/wear surface rotating against the bolt itself. Typical "sleeve bearing" design.

[jrevens]

...

Installed the parking brake valve assembly to the console temporarily. As an observation, installing the 90 Deg elbows permanently could be interesting because the ports are so close together that the elbows obstruct each other when you turn them to thread them in.

...

Hi David,

You are making good progress!

If you have a Matco valve, the individual sections are designed so that you can rotate them in relation to each other to allow installation of 90 deg. fittings.

[David47]

Yes Josh and John, that's correct. The hinge bearings I sanded down are those that rotate within the press fit bushes. I haven't fitted the elevator to the stab yet but I'm assuming the bearings will be slightly longer than the press fit bushes so that on clamp up, the bolt and bearing will be stationary and the elevator press fit bushings will rotate against the inner bearing. So torquing of these nuts and bolts becomes critical to correct functioning of the joint.

Unfortunately, I didn't have the forethought to take a photo of the interference between the stab centre hinge and the fuselage attach bracket. I suspect tolerance stackup is working against me. But I'll take a photo so you can see what I mean.

John, I haven't looked at the branding on the handbrake valve assembly but I'm sure you're right. I'll look a little closer at it.

Thanks for the feedback everyone... much appreciated.

[David47]

Another productive weekend working on the project. This weekend was concentrated on the door and window frame fabric angles and the empennage access panel angles.

Took quite a bit of “fitting and fettling” to the door frame fabric angles to get them all fitting reasonably well. Sadly my sheetmetal working skills were way better when I did this at secondary school decades ago. Also, it didn't help that the planes of the door frame angles differ at the very point where you also attach the fuselage side stringers. Any ambitions of doing a neat lap joint of the angles didn't work out so I whimped it and made a mitre joint with a bracket connecting the two angles. The end result is quite good and the transition between the two planes should make for a neat fabric layup. The side stringers neatly fit inside this joint and were riveted to the fabric angles. There’s obviously a bit of residual spring in the stringers but that should be partially alleviated when the fabric is applied. I must say there’s a surprising amount of work in getting these angles to fit up, well at least three was for me. It took a good 6-8 hours of fiddling around and wearing a path back to the grinding wheel, vice and file. But the end result is not too bad. Just don’t look too closely at the mitre intersects !.

The empennage access panel attachment angles were made up and scalloped out to enable them to take up the profile of the lower most rib and forward bulkhead. Bonding of the bulkhead in place was not a huge success when it comes to neatness and cleanliness. I used a popsicle stick split down the middle as the application tool. Not a great result so don't look too closely at the mess of Hysol at, in particular, the upper joint. I also used popsicle sticks as shims and standoffs for positioning the bulkhead prior to bonding. They work a treat.

Some photos follow.

[Cherrybark]

Those window frame pieces were an interesting puzzle and, as you said, took many trips back and forth between the plane and the workbench. I think you did a very nice job.

SuperFill, an epoxy filler and faring product, can be used for finishing the gaps. If that's not readily available, consider West Marine system and their 410 Microlight faring filler. To me, the West system is much nicer to work with than the almost too dry and crumbly SuperFill.


(http://www.aircraftspruce.com/catalo...clickkey=20637

[jiott]

Carl, I'm surprised you find SuperFill dry and crumbly. Maybe your SuperFill is too old and dried out? I find it plenty wet and very easy to use and feather out. In fact, if applied too thick it will tend to sag somewhat before it sets up. I also find it much easier to sand and work down to a feather edge than epoxy finishing resins-they are too hard and tough. Just my experience.