Time to turn my cardboard prototype into a permanent bracket for the heater valve.
Since this bracket will sit freely, I decided to use 0.05in thick aluminum to give it some strength.
Just like the standard bracket that would usually hold the bowden cable, I designed the bracket to mount into the heater valve unit. So I added the size of the screw mount portion of the original bracket to my cardboard bracket part.
With the outline made, I got out the aviation snips and started cutting out the bracket.
Next step, releasing some tension. To make the bend, I mounted the bracket along the bend line in my bench vise. And then gave it some gentle (read strong) taps with the rubber mallet to form the bend.
And here it is, a nicely formed 90 degree bend.
Next I deburred all the edges and rounded out the corners.
And then I match-drilled the holes to mount the bracket to the heater valve using the original bracket.
Finally, time to mount the servo to the new bracket. Quick test fitting with a clamp to get the travel distance right.
I started with my cardboard pattern to match everything up for the left side. Everything looked good, so I started cutting out the bracket out of 0.032in aluminum stock.
I recently ran across this very helpful video on how to properly use aviation snips. This made it a lot easier to cut things like the bracket.
Cutting the bracket using some of the tips from the video to cut a sacrificial strip of metal to keep everything straight.
Once I completed cutting it, I removed the protective plastic and rounded the corner and edges.
Then time for the final test fit in the airplane before match drilling the holes.
All worked well, here’s the completed test fit in action:
Cabin Heater fluid valve
The third and final modification I’m making in the cabin air department is the valve that controls the heater fluid that runs through the heater.
The standard installation controls this valve using a Bowden cable connected to a plastic switch to be mounted in the cabin.
So on to some prototyping to figure out a bracket to operate the valve using the servo instead.
Looks viable, here’s the cardboard prototype in action:
With the assembly of the Rudder pedals that sit right below it done, I now moved on to actually putting this together.
I temporarily placed the dash in place to make sure there won’t be any interference with the bracket I designed for the servo mount.
All looked good, so I moved on to fabricating the bracket I designed earlier out of cardboard.
I decided to use some 0.032in thick aluminum to give the mount some stability and rigidity.
After that I match drilled the hole for the servo mount through the template, marking the hole using a center punch.
Then I mounted the bracket in the plane using some clamping clecos in order to match drill the holes from the air vent.
With both holes drilled I then clecoed the air vent in and mounted the servo for final testing.
I’ll shorten the screw of the servo mount as it’s a bit longer than it needs to be as can be seen above so it won’t interfere with the parachute cable.
Here’s a video of it in action:
Now I just need to replicate it for the left side and then I need to install it permanently.
First order of business was to remove the protective plastic and do some inspecting and deburring of the edges and holes.
With that out of the way, time to assemble the main rib structure.
On the bottom rib there was a minor misalignment of the rib. The rib extended a little bit beyond the skin, but the holes were all drilled fine.
So I trimmed off the small part that extended too far.
And on to more ribs to make it a really solid seat.
The last part was to put on the front skin and make sure everything lines up. When I first clecoed it on some of the ribs didn’t align, so I unclecoed the skin again, then centered it and clecoed it again and everything fit well.
Last week I finally received the cabin air parts after the lockdown in the past few months that put a hold at the factory for sending out new parts, but they are back up and running.
The cabin heat assembly for the TSi has a mixture of forced air from a NACA duct getting air from the outside when the plane is moving, together with an actual radiator heater, for those times where you don’t want cold outside air and instead heat it. To shut out the outside air, the TSi has a butterfly valve that’s operated by a handle from the panel.
I am planning to replace the manual handle with a servo instead and also replace the front standard plastic vents that come with the kit, with some ball vents typical in airplanes.
I got the Aveo Air Maxi Vents in black since the front is black leather, so it blends in nicely.
Butterfly valve servo
The servo I’m going to use is from TCW that comes with a linear servo from Actuonix, together with TCW’s control board with the control knob to operate the servo.
The first thing I had to figure out is the travel of the butterfly valve, it is around 40mm long. I made a small cardboard panel, clamped it to the bracket of the box that houses the butterfly valve. Based on the maximum extension I then mounted the back of the servo onto my cardboard panel. Then I tested that retracting and extending works correctly from that position and made small adjustments to the travel distance.
Here’s a small video of testing the operation:
With the operation figured out, then I went to check for alignments in the cabin.
First I had to figure out where exactly the vent box sits inside the cabin. Some quick measuring for the distance based on the construction manual.
Then I put in the channel that moves air to the rear passenger seats to make sure there is no interference wit the operation.
Looks all good. Next step will be to fabricate the bracket out of aluminum.
After a couple of weeks of taking some time off active building while life happens and figuring out and planning out some things, I’m back to actively riveting on the airplane.
Time to finish the Pitot Tube after having cut the inspection panel hole and running the wiring a few months ago and lots of learnings about new tools, from the wiring, to flaring the tubes and connecting AN fittings.
I’m using the Garmin GAP 26 heated & regulated Pitot Tube (GAP 26-20). This version automatically controls whether the Pitot Tube needs to be heated using a regulator controller that is mounted next to the Pitot Tube and will only apply heat if needed based on outside temperatures. This basically will allow me to always turn on the Pitot Tube in my panel as part of my standard operating procedures and the regulator will control whether it actually needs to be heated to prevent icing.
After studying the installation manual to make sure I install it correctly, I measured the tube and had to figure out how far I have to cut it in order to fit.
Fitting the Pitot Tube
The Pitot and Angle of Attack (AOA) mast are over 12 inches out of the box, and that won’t fit. I made an initial guess and cut a bit shorter, but I was still too long so I made a series of shortenings and test attaching the fittings until I had it dialed in.
In the end, I had the masts cut down to right around 8 1/2 inches. The Garmin manual says to keep a minimum of 8 inches between the probe and transition to non-metalic tubing, so I had a little bit of margin.
Time for flaring the tubes. The AN fittings use a 37 degree flare, so I got a Rigid 377 flaring tool and a metal tubing cutter to cut the tube. Before doing this on the real Pitot Tube, I made some test flares on a spare tube I bought from Aircraft Spruce.
Make sure you put the AN fittings onto the tube before you do the flaring (I may or may not have forgotten it the first time and cut and redo the flare once).
After I had that dialed in, I did another test fit to get the length correct, accounting for the bend towards the tube and then mounted the fittings.
Final fit and connecting to the nylon tubes inside the wing after having cut the nylon tubes.
Installing the regulator and wiring
With the Pitot Tube itself installed, time to finish the regulator and wiring that controls the heating of the Pitot Tube.
As I explained previously, I plan to mount the regulator unit onto the inspection panel plate, so I did some measuring and orienting to make sure the twist action of the round plate wouldn’t interfere with the wires coming out of the regulator.
Here is the final orientation that I figured out would work best (the screw will mount to the bottom, so the wires will come out the top):
I contemplated between screwing or riveting it on, but I figured that it’s unlikely that it will need to be changed out frequently, so I riveted it onto the plate.
The last part was to create a connection from the regulator to wires I ran through the wings. I used some weatherpack connectors for this, which create a waterproof connection and a solid crimp, similar to the Delphi GT 150 that Midwest Panel uses to connect the wiring harness.
Final completed connection between the regular, the Pitot Tube and the wires running to the center.
Installing the plate to the wing
The last and final part of the installation was to mount the inspection panel plate onto the wing. I did this last to prevent scraping up my arm while I had to do all the mounting inside the wing, since the backing plate that holds the plate in place has a series of pokey corners that love to eat airplane builder blood.
First I lined up the plate with the wing and then did the match drilling of the holes:
The I dimpled the plate and the matching holes on the wing and riveted it in place.
And here is the completed and closed up Pitot Tube and Inspection Plate that holds the regulator:
I figured out where I want to run the wires a while back after some tinkering and I am using one of the strut channels for the length of the wing, except the very end at the wing-walk where I had to make one curve down the bottom.
The hardest part was figuring out a good way to come out the bottom where the wing-walk is, since the strut channel doesn’t go through there. On the last picture above, you can see when I finally managed to grip on to where I want the loom to come out of with the help of some duckbill pliers, which were a suggestion from my EAA chapters Technical Counsellor when he visited a few months ago.
Running the wire
With the question of where to run the wire solved, onto actually running the wires.
I am installing the Garmin GAP 26 Heated/Regulated Pitot Tube, which comes with a Regulator that needs to be installed next to the Pitot tube and controls whether the Pitot tube actually needs to be heated.
For this, there are three wires to run – two for the power and one for the discreet output, which integrated into the Garmin G3X Panel to show when the Pitot Tube is actually heated.
I ran the three wires through some braided sleeving to give them some extra protection and make running them through the wire channel easier in one go.
With that out of the way it “just” took a lot of back and forth, more use of the Endoscope and the thin arms of Juliana and repeated shouts of “push, push” and together we managed to run the wire all the way. She cheerfully pronounces “Congratulations, it’s a wire” as it came out the other end.
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.
With all the marks in place, I started with cutting the pilot holes for the center mark and the cutting head.
The final moment of truth – Time to cut the hole for the inspection panel using my nibbler cutting tool.
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.
The cut came out pretty well and I just had to do a little bit of sanding to smooth the edges.
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.
Aside from that, I just went to town and pulled the rest of the few hundred rivets.
The last part on the riveting side was 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.
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.
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:
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.
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.
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.
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.
Annotated video of the process of cutting the hole
