Cutting Pitot inspection panel hole

Hours: 1.5

I was planning to finish to Ailerons, but unfortunately in my final prep, I realized that I received two right side balance tubes instead of a left and a right one. The missing tube should be here sometime next week, so until then, the Ailerons are on pause.

This gave me some time to finally make the big step of cutting out the hole in the Wing for the Pitot inspection panel. I received the heated & regulated Garmin Pitot tube from the Factory and verified that it will fit nicely on the back of the round inspection cover, so I will mount that and I can keep my square inspection panel I designed for some other time.

First I did a lot of measuring and marking based on the plans. Since this is truly a moment of measure-twice, cut-once I measured and re-measured a few times.
Marking the center and hole to cut out Hole marked and alignments checked Time to prepare the cutter Marking the pilot hole for the cutter

With all the marks in place, I started with cutting the pilot holes for the center mark and the cutting head.
Using the center punch to mark the pilot holes Using the step drill to upsize the cutter pilot hole Pilot holes drilled

The final moment of truth – Time to cut the hole for the inspection panel using my nibbler cutting tool.
Time to cut a hole in the wing

I cut the first half of the circle and then reversed the tool since the Pitot tube mast was in the way of completing the cut in one direction.
First half of the circle cut - I had to reverse the tool at this point since the pitot tube mast blocked finishing the circle from this direction

The cut came out pretty well and I just had to do a little bit of sanding to smooth the edges.
Inspection hole cut Temporary placing of the backing plate Inspection Cover fits perfectly

 Timelapse video of cutting the hole

Aileron ribs priming

Hours: 1

I prepared most parts of the Aileron a good while ago, but I was missing a replacement for one set of ribs that were damaged, so I had put the Ailerons aside and finished the Flaps and Elevator in the meantime.

Now with the Elevator done and the replacement ribs in hand, back to finishing up the Aileron. After a quick inspection and deburring of the new rib I laid out all the parts and got out my small painting booth to prime the ribs.
Aileron ribs laid out for the left and right side Paint booth setup to prime

Once the primer is set I can get onto assembling everything and riveting the Aileron.

One side of Aileron ribs primed Primed Aileron ribs

New Sling Pilots community website & forum

A small non-direct building post for a change to talk about the new Sling Pilots community website & forum.

We recently had a discussion on the Sling Builders Facebook group about the very visible growth of the Sling Airplane community. With the bigger size, the community is slowly growing beyond the size of a Facebook group. There are also some people do not use Facebook, so a separate forum allows more inclusion for everyone.

So armed with that, we have started a new community organized standalone website and discussion forum that will hopefully help both active builders, people interested in possibly becoming builders and active Sling Pilots to come together and discuss all things Sling.

Check it out at https://www.slingpilots.com/

Cheers,
Philip

Finishing the Elevator

Hours: 2.5

With most of the preparations out of the way and half of the skins riveted, I took one more session to finishing the Elevator.

There was only one extra part I had to do for 3 of the rivets that were on the bottom edge. In order for them to fit correctly, I had to shorten the rivets so they wouldn’t protrude out.
Rivet too long to fit Fitting rivet after I shortened it I mounted the rivet in my bench vise and filed it down to size Shortened Rivets on the right and one with normal length on the left

Aside from that, I just went to town and pulled the rest of the few hundred rivets.
Time to pull some rivets Halfway done riveting the skins Final set of rivets ready to be riveted Riveting the Trim Tab

The last part on the riveting side was the front lip.
Clecoing the front lip Riveting the front lip

One of the holes on the lip has to be enlarged to fit a grommet for the wiring for the Elevator Trim Tab. I enlarged the hole using my step drill bit and then installed a snap bushing.
Marked out the hole that needs to be enlarged for the wiring Marked out the size on the step drill bit Hole enlarged and Snap Bushing installed

The last part was to install the center balance counterweight. I did some test fitting with this, but the AN3-13A bolts that one of the versions of the manual that I have mentioned are too short, so I’ll check with the factory on the proper length.
Test fitting the Balance Counterweight - the bolts are too short

With that being said, the general assembly of the Elevator is completed:

Timelapse of the complete construction of the Elevator

With the Elevator construction completed, I’ve also finished my video timelapse of the process:

Riveting the Elevator skins

Hours: 3.5

With the final preparations and alignments of the Elevator done, the last task is to rivet up the Elevator skins.

Horizontal Stabilizer and Elevator temporary joined for alignment and looking good

The process is pretty straightforward, but there are a lot of rivets to be pulled, so it’s a lot of repetition, so I spread the work out over a few sessions.
Setting up rivets Almost done with the left underside Finished left underside

I first did the half of the bottom, both left and right side, and then finished up the left side completely, followed by the right side.
Setting up the final few rivets for the right underside Bottom of the entire Elevator completed

For the Trim Tab control tabs I had to get out the close quarter wedge.
Using the close quarter wedge to be able to attach the rivets for the Trim tab Control

After I finished the entire bottom half of the Elevator I flipped it around and put a small padding onto the Trim Tab control so it can’t dig into the Elevator skin.
Protection for the Trim Tab control

Final Elevator fitting

Hours: 2.5

After reinforcing parts of the fiberglass tips for the Elevator for the front section that is countersunk to support the flush rivets, I finished fitting of the right side of the Elevator.

When I finished the alignment of the left side of the Elevator, I ran out of clecos, so I bought a couple more when I was at Oshkosh so I could properly put the Elevator together and get everything to align correctly.

So the first order of business was to finish clecoing everything including the (correct) control tabs for the Trim Tab.
Time to cleco the right side of the Elevator Everything clecoed together including the Trim Tab

With that out of the way, I moved on to do the fitting for the right side fiberglass piece. It took a little bit of aligning and filing away a tiny bit from the back so that the fiberglass piece can slot into the metal.

Once that looked all good, I started to do the match drilling of the holed into the fiberglass.

Time to drill some holes into the fiberglass tip First hole drilled and clecoed Continuing the match drilling All holes drilled

Now the only last part to do was to countersink the front parts of the fiberglass tips in order to allow the flush rivets to sit in there. It took a bit of back and forth to calibrate my microstop countersink attachments to ensure I had a good flush fitting.

Marked out for the holes that need to be countersunk Finished countersinking the holes Flush fit of the left side Alignment checks on the right side

EAA SportAir Electrical Systems & Avionics Workshop

This past weekend I attended the EAA SportAir Electrical Systems & Avionics workshop at the Seattle Museum of Flight Restoration Center.

The two day workshop helped in explaining principles of airplane electrical systems, wiring and bringing everything together to design and build out your avionics.

Workshop Handbook

Aside from a lot of good learnings and explanations, there was also a couple of hands-on exercises to get familiar with crimping, soldering and connecting things.

The first exercise was to hook up a headset jack to a PM1000 intercom system. This was very handy, since whether you decide to build all your avionics or not, you will most definitely have to do the headset connectors.

I forgot to take pictures of the process, but here’s the finished headset jacks with the soldered connection. This included learning to ground the shielded wire, soldering the actual headset jack and doing some d-sub crimping for the intercom connector.

Finished Headset connector and crimped BNC Antenna connector

Also shown in the image above is the result of the second exercise, a crimped BNC antenna connector. This part, I was already familiar with from hooking up my NAV Antenna in the Rudder a few months ago.

The final exercise was to create a small electrical circuit. This includes a “master” switch, circuit protection in the form of a fuse and a dimmable “cabin” light that is tied behind the master switch. Aside from the practical application of the exercise, it also tied together a lot of the theoretical parts of the workshop and was a great finish for the weekend.

Getting started Wiring in progress System wired up

Here’s the finished working circuit in action:

I also ran into two other Sling Builders, Richard Howell, who recently started building a Sling 2 and Skip Jones, who is also building a Sling TSi. Now we just need to all finish building our airplanes and then we can be a chapter of Sling Pilots in the Pacific Northwest.

Cutting a round inspection access panel hole

Hours: 2

One of the things that the factory forgot as part of the change from the Sling 4 to the Sling TSi was the required access to the internals of the wing next to the Pitot tube.

In the Sling TSi design, some inspection panels were removed including the one next to the Pitot tube. By itself, if someone was building the wings from scratch, that might be fine as long as the builder installs the Pitot tube beforehand and doesn’t anticipate to ever need to access it, such as if using an unheated Pitot tube.

However, I am going to use the Garmin heated & regulated Pitot tube, which not only requires wires to be run to the Pitot tube, but also that I need to mount the regulator unit next to it.

Since I ordered the quickbuild, I ordered it with this specification, but unfortunately the factory didn’t receive the Pitot tube from their supplier in time and shipped my kit without installing it.

So after I received my shipment and inspected everything, I realized that installing this after the fact wasn’t going to be easy, particularly with the lack of a hole in the wing. Unfortunately the factory also forgot to run the wiring to the pitot tube, which creates a whole second issue, for which I’ve been working on a solution.

I informed the factory a while ago and also gave Matthew, one of the other TSi builders a heads-up since he hadn’t started on the wings yet. The factory realized their mistake in the plans and promised to come up with a solution and send me instructions and a plan.

Drafting a plan

While I was waiting for the factory to come up with a plan, I actually started drawing up my own plans to fabricate the entire inspection panel myself and used it as an opportunity to learn and use Solidworks, which I can use for free as part of being an EAA member.
Initial draft of the panel on paper My panel design in Solidworks

Since I had the chance to chat with Mike Blyth at Oshkosh for a while and we chatted about my build, I mentioned that I was still waiting for the factory to come up with a plan for the inspection cover and he promised that he’d check on the progress when he got back to South Africa and indeed, two weeks later, I got an email with the plans.

The factory plans, in keeping with the other inspection access panels, uses the same flush round inspection cover that is used to access the Flaps and Aileron connecting rods.

Factory plans for the new inspection access panel

Since I am still busy with other things in the build and haven’t actually made my own panel yet, I am going to go with the factory plans that they have drawn up for me.

Cutting a round inspection access panel hole

There is just one difficulty to overcome – the access panel is round and large and I don’t think there are 143.4 mm drill bits I can buy in Home depot.

After a bit of research, I found a solution in using a drill attachment sheet metal nibbler that can cut around a center pivot and can attach to my Milwaukee hand drill.

Since this is quite an operation, I decided to get some practice with the tool on a piece of spare aluminum and also made a video of it, since I figured that it might be helpful for other builders in the future.

I started by marking out the circle using a drafting compass. It’s been quite a few years, but luckily I still remembered how to use it and how to find the center of the circle again by making two marks. Proof that you may indeed use what you’ve learned in geometry class sometime in life, even if it’s 15 years later. After that I clamped the piece of metal on the edge of the table.

I drilled the center pivot hole to 1/8th of an inch, which makes the pivot sit in the hole and then measured out the starting hole for the drill, make a starter hole and then used a step drill bit to upsize the hole until it aligned with my marked circle.

After that, I set up the drilling tool with the pivot and made sure that the outside of the cutting bit aligns with my circle and then attached the drill and went to work.

Here are a couple of pictures of the first circle I cut – note that briefly I had the pivot point jump out of the hole, which caused me to waver a bit which you can see towards the bottom where it’s not perfectly round, so make sure the pivot continues to stay in the hole.

Marking out the circle using a compass Clamping down the metal on the table Cut hole and the inside disk - I did waver a little bit on the bottom as I didn't hold the pivot in place perfectly for a moment. So practicing this will pay off to not repeat the mistake. Inspection cover "test fit" Tools used to cut the access panel

Annotated video of the process of cutting the hole

 

Elevator Fiberglass tip countersink reinforcement

Hours: 1

The leading edges of the Elevator Fiberglass tips have flush rivets and so they need to be countersunk. The parts that need to be countersunk are reinforced to add thickness, but the reinforcements on my fiberglass tips wasn’t long enough, so I had to add some more so I can finish them.

As you can see in the picture below, the black reinforcement doesn’t go far enough for the last two rivets on the left that are also dimpled flush.
Reinforcement not long enough for the countersinking Marked out how far I need to extend the reinforcement

I got some one inch wide fiberglass cloth tape and mixed some epoxy to extend the area that needs reinforcement. I marked out how far I needed to extend and cut strips of the fiberglass cloth to size to apply.
Epoxy mixed and ready First layer applied

A few layers applied and set out to dry for a few hours and then I can countersink the holes.Finished with the reinforcements

Oshkosh 2019 recap

It’s been a busy few weeks after returning from Oshkosh, so it’s been a while since I’ve written an update.

Since I spent the whole week at Oshkosh, I had a lot of time to figure out various bits and pieces that will go into the airplane and talk to the various vendors. I also finally got to meet Adam and Steve from Midwest Panel Builders who I’m working with for the Avionics.

It was great to get a feel for various things including the control sticks – I will go with the Tosten grip.
Tosten control grip

Another thing I was looking at is the TCW Control Valve servo for the vent shutoff valve that the TSi has. The standard design for this is a physical shutter that I’m not a great fan of, as I feel it looks a bit out of place in the panel. So I was looking for alternative options and Adam mentioned this servo as a possible option. After I checked it out, I think indeed it might be a nicer solution and I will try to make it work. In fact I might also use it for the heating control.
TCW Control Valve servo

Aside from figuring out things for my own build, I also attended a lot of seminars, saw a lot of cool airplanes and the airshows and met a lot of interesting people and stories.

I also spent a lot of time lurking around the Sling tent and checking out various details of the completed Sling TSi that they had on display there. It was nice to see how a lot of the small details to the plans for the fit and finish were in this plane, which didn’t exist in Wayne’s TSi yet.

I was also able to meet a few of the other Sling builders at the Sling Ding meeting and had a long chat with Craig and Austin about our various builds. And I got to meet John & Marta King who I have to give credit to getting me through the ground school of my private and instrument training and ran into a few other people including Angle of Attack, Aviation 101, Jason Miller, JP The Candourist and Mike Patey and Draco the bush plane.
John & Martha King Angle of Attack, Aviation 101 and Jason Miller JP aka The Candourist Mike Patey Draco