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Showing posts from February, 2017

Empennage lighting

The empennage is a relatively simple thing, 4 surfaces (vertical and horizontal stabilizer, rudder, and elevator).

It does however "contain" 2 systems: Electrical trim, and lighting.

Lighting can be subject to regulation, and in Canada, is indeed, even on home-built aircraft.

The rules are : Standard 625 Schedule 1 - Position and Anti-collision Light Systems

Not as stringent as the certified rules, but more stringent than US rules. As it turns out, the Sling 4 kit, as provided, does not let me meet these requirements. I will need to improvise.

The big problem is the requirement to have a steady white light facing aft though 140 degrees, like this. Although there is an alternative solution of using two steady white lights on the wing tips, the way the lights mount on the Sling 4's wing tips, that won't work, as they will not provide the required projection.

You can see why here. They angle forward and downwards somewhat. Even with white aft lighting on the wing tips, …

Riveting decision

I'll spare you the suspense: I'm not going to do it.

Here's why:

From a strict engineering perspective, I shouldn't:The holes are over-sized, even for an over-size rivet. Rivet manufacturer says I should not do this.Even the clamping force doesn't seem to do enough to provide proper full grip. The hole does not "close in around the rivet" as I had hoped.As it turns out, the best-bet rivet for this application does NOT have an expanding shank. It really wants a tight fit from the get-go.My tests were done without reaming, which would enlarge the holes even more, and make the problems previously identified even worse.Being in a slightly too large hole, the rivet can set off-center, which is highly undesirable.I can't find any other combination of rivets/tooling that comes close to the over-sized CherryMAX approach.These rivets are quite expensive, would likely add 1000$+ to the project. I probably wouldn't be ahead financially in the end, as the very…

Flush riveting experiments

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Before getting to building my empennage, I still need to determine whether I will be able/willing to attempt a flush riveted Sling 4.

I tried a number of things, and took lots of pictures, but I'll try to summarize the process and keep it short. Don't hesitate to contact me if you want details.

General process:

Take some spare sheet metal 6061-T6, 0.016 thickness (That's the skin material).Make two parts that I will rivet together.Drill 1/8th holes (3.3mm), one in each part.Dimple each part with a standard 1/8th dimple die.Rivet the two parts together with a CherryMAX oversize flush head pulll rivet CR3242-4-2.Observe closely.Cut down the middle, and observe closely again.See if I think such a joint will hold up. Here is what one will see when analyzing the hole and dimpling process:




The first sample I assembled, I kept for eventual shear testing.

The second sample gave something like this:







Note how the shop end (the "bulb") doesn't seem to quite cover the ful…

Empennage unboxing

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Here is what an empennage kit looks like once opened:

Basically, a packing list, a manual, and a bunch of parts!
The contents are arranged in a number of sub-packages, which are either "assemblies" or "hardware", and I also have some "extras".
For example, here is the rudder assembly as it comes out of the box:

And with the contents spread-out for inventory taking:

And here is what the hardware bags look like:

As you can see, everything is nicely organised and packaged. Everything categorised by assembly, and each assembly being assembled as a unit, per the manual. So, the first thing in the empennage manual to be done is the horizontal stabiliser, so we'll pull out the "assembly" and "hardware" bags for that piece of airframe, and get cracking!

Empennage kit arrival

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My first kit, the empennage kit (Basically, the tail), has arrived!


Tiny bit of damage on one corner of the box, but looks superficial ...