Good day in the shop today. Time to start plumbing the wing for pitot, static and fuel lines. 50 feet each of blue and yellow nylon line and 20 feet of Earls's Auto-Flex fuel line:
I'm not ready to get the fuel tanks welded yet, but they are taking up a bunch of room on the bench, so I "dismantled" them for storage. Before putting the skins away, I decided to drill out the drain hole.
Step drill brings the hole up to 18mm diameter:
The tank drain fitting will be welded here and eventually will have the drain valve installed.
Before flipping the wing upright, I cleaned up the bench completely. It was getting quite untidy with all the bits, pieces and other tools. I laid down some green tape runners on the lower skins to help protect the skins where they will ride on the steel bench tubes.
Ron helped me flip the wing over and I was pleased to see the tape runners I put on the upper skin helped prevent most if not any scratches:
The nose skins are just wider than the bench when they lay flat, so I tagged the corners with a bit of yellow tape . It won't protect the corner, but it catches the eye when walking by.
Here is a better look at the pitot/static tube inside the nose skin now that the wing is upright. As mentioned before, I'll need to trim the length a bit to leave room for the the union connectors:
Here the connector unions in place on the end of the tubes. They point right at the spar web, bending the tubes into the lightening hole isn't practical.
A couple of holes in the spar web are necessary for routing the lines, but I like this better as it is another way to support the lines as they pass towards the rear channel:
Grommets protect the lines in the holes. I won't be connecting the probes until later as I work on wrapping the nose skin. Blue line is pitot (airspeed) and yellow line is static pressure (altimeter, VSI etc.):
The lines pass through the wing bay and out through the rear wing channel, again through grommets to protect the lines:
Not all leght of this line will end up in the airplane, but I'm not cutting anything I don't have to (less cuts means less potential leaks/failure points). For now it stays coiled up. Eventually it gets routed through the cabin, under the seats/floor and up to the instrument panel. I'll likely need more union/elbow connectors, but that's a ways off yet.
Next I worked on laying out where the fuel line leaves the left wing tank and travels though the inboard wing bay rib and eventually through the rear channel and out inside of the trailing edge to the fuselage.
The outlet fitting isn't welded yet, so for test fit I taped it in place:
The inboard tank rib (side of tank) sits inside the fuel bay of the wing once part of a completely assembled tank:
I lightly clamped the rib in place. The goal here is to approximate the location of the pass through hole in the wing rib foward/rear, not the distance laterally (left/right):
I marked the location of the pass through using a Sharpie through the centre of the fitting then drilled a pilot hole in the wing rib:
Using a the step drill, I enlarged the passthrough hole a little at a time until the finger strainer fitting from the tank could fit through. The aluminum plate is a piece of scrap I placed on the lower wing skin to protect it from scratches from the drill chuck:
I traced the size of the fuel outlet fitting centred on the passthrough hole, then enlarged it a bit more. This will give me a bit more room when I install the tank. The fittings and line just need to pass through here, they don't actually fasten to the rib.
Looking at the wing tank rib, facing inboard with the finger strainer in place:
Looking at the finger strainer, outboard towards the wing tank:
I can't do much more tank fit up until I get the fuel caps and fuel level sending units I ordered.
Looking back inside the wing, I needed to come up with a way to support and protect the pitot/static lines from rubbing on anything from vibration. The lightening hole flanges of the nearby wing rib face toward the lines, so clipping them to the surface of the rib won't work.
Using some scrap 025 aluminum that was already bent 90 degrees, I created some stand-off brackets
While the standoffs dried after priming, I remembered I needed to final torque the forward wing strut attachment bolts - so much easier with the wing upright!
Some 1/4 inch cable clips facing back to back get rivetted to the standoff then the standoff rivetted to the wing rib:
Nice and tidy and secure from vibration damage:
The standoffs are perfect, very pleased at how neat this arrangement is. Once the final fit of the lines are done at the pitot/static probes, I add a wire tie on the lines to prevent them line from sliding back and forth in the clips if needed:
Gentle bends supported well prevent the lines from kinking. There is plenty of room inside the trailing edge for a large radius bend in the lines as they exit the rear channel:
Cable clips avery 11 inches spaces out nicely along the face of the rear channel as the lines head inboard towards the fuselage:
Tied the nose skin up a bit with some twine which allows anyone walking around the bench when I'm not working on the wing to do so:
Good productive day. Waiting now on some plumbing fittings, fuel caps and fuel senders. I've got to drill and grommet the fuel line hole in the rear channel, then I can fir the trailing edge. While I wait for my orders to come in, I'll get the nose skin slotted for the slat pick-ups and wrap the nose skin.
More to come, thanks for following along.
Fuel lines and fittings have arrived. Stainless braided Auto-Flex line and Swivel Seal fittings. Expensive but the peace of mind this provides is worth it. This is one area of the plane I refuse to compromise on. Very impressed with the quality of Earl's Performance products. With these in hand I can start laying out the fuel tank plumbing.
I've been wanting to figure out a way to measure the fuel level in the tank that requires no internal sensor - less holes in the tank means less chance for leaks. There are several stories on the builders forums about tank sensors mounted through the sides of the tank leaking or being terribly inaccurate, hard to service and generally failing.
I wondered if there was a better way, and I originally came up with the following. A very sensitive presssure transducer (the chrome unit with yellow label below) that will measure the "head" pressure of fuel in the tank via a "T" in the fuel line next to the tank. In theory this should work using an Arduino microcontroller to read the sensor and output a value to a gauge. Here is the assembly mocked up on the bench. From right to left - finger strainer (inside the fuel tank), tank fitting (through wall of tank), threaded adapter, threaded "T", coupler and pressure sensor), fuel line fitting elbow.
Testing of the system has proven difficult. I've been unable to get consistent readings from the sensor in a static set-up. The programming of the Arduino works fine, I'm just not happy with the accuracy of the output due to the very low spread between empty tank head pressure and full tank head pressure, which given the depth of the tank is about 1.5 PSI. I'd hoped a programming algorithm within the Arduino to amplify the input values and stabilize the readings would work, but it's become too much of a tail chase to get it right. From there I'd still need to figure out how to smooth the values to account for changes in atmospheric pressure (fuel changes "weight" with changes in altitude) and aircraft attitude - banking towards the sensor increases head pressure, banking away reduces head pressure.
In an effort to focus on the build getting moved forward, I've decided to abandon this concept in favour of a top mounted float sensor. Yes, this means another hole in the tank, but if mounted from the top, the risks of leaks is minimized and the ability to service the sensor if needed is much easier. More on this later.
So removing the pressure transducer from the fuel line leaves just the tank strainer, the tank fitting and the elbow. I'll need to order the fitting that goes between them, but they are inexpensive and easy to obtain.
The tank fitting is a one direction NPT thread. This picture shows the fitting as it looks from the outside of the tank.
These fittings were gifted to me by another builder. They are actually the larger style, so I need to modify them slightly to fit the tank side rib so the strainer sits nearest to the bottom of the tank as possible. Trimmed them using the bandsaw, then cleaned them on up the disc sander.
The smaller diameter of the fitting needs to fit through the tank rib from the inside. I don't have a drill bit this size to make the hole, so I had to improvise.
I confirmed the fitting was trimmed enough by laying in on the outer face of the tank rib:
I drilled a pilot hole equivalent to where the centre of the fuel strainer will be on the tank:
Used a large step bit to create the general shape of the hole almost up to full size in the tank rib:
Laid the fitting centred over the hole on the tank side of the rib and traced the final size/shape:
Clamped the rib to the bench elevated on some blocks, then used the Dremel tool with spiral cutting bit to carefully bring the hole close to size using the trace lines as my guide:
Filed the hole to final size to ensure a tight fit:
Here is the fitting in it's final position looking from the inside of the tank rib.
On the outside of the rib, the fit is really good:
With the finger strainer in place
Bending the tank skins can be tricky. It is paramount to ensure the bends are as tight as possible to the corners of the tank ribs to reduce any gaps that will need to be filled when the tanks are welded.
I wrapped and finger clamped one of the ribs with the seamstress measuring tape (very handy long ruler for any project) to get a general measurement of where the corners of the tank skin will be. This picture is of the second tank taken later in the day (left tank had already been through this process and I forgot to get a picture for the blog):
The throat depth of the wide bender isn't deep enough to get to the middle tank skin bends, so I needed to use the heavy bender. To allow full access we moved it out into the open floor area, rather than roll up the paint booth curtain (Ron is painting currently).
First I laid out the 025 skin and marked the approximate location of the first bend. Like the slat skins, order of bending is important here, working from middle out to ends. I've left the skin a bit long at each end to make sure it doesn't come up short once it is bent to shape:
The heavy bender allows for material to pass through, giving full access to the middle of the sheet:
First bend complete, next was measuring the second bend closely to make the corners tight
Finger clamped the ribs in position to get a good measurement where the next bend would be:
Second bend line laid out (note the little circled "2" I used to remind me of the bend order):
Back on the bench, I discovered the second bend was slightly overbent and the process on the bender had opened up the first bend as well.... I corrected both before moving forward, but swapped the bend order on the second tank which prevented this from happening again.
Left tank skin rear corners corrected and test fit shows good:
Marked out the location of the fuel filler neck:
Front side of the tank skin bent up to meet the top skin and close off the tank:
The front side of the tank skin needs to have a 5mm flange bent forwards to create the seam for welding. I puposely waited to bend this flange as I didn't know where the bend would be until I mocked up the tank:
I tipped the tank forward on its nose and clamped the forward tank skin onto a piece of aluminum angle at the bench edge:
Using a deadblow hammer I caefully bent the 5mm flange forwards to match the top corners of the tank ribs:
Reassemble the tank and use Cleco vise clamps to hold it together. Some final tweaking of the rib flanges squares it all up - very happy with the final shape! The extra material overhang on the top side of the skin will be trimmed back to match the flange.
Marked out the fuel tank drain location which is directly below the fuel line fitting. This is the lowest spot in the tank once it is mounted in the wing. It is from here that fuel is drawn during pre-flight to check for contaminants such as debris or water:
The right wing tank went faster now that I have the benefit of a process from the first. Fuel outlets are on the opposite side of the left tank (the face inwards towards the fuselage:
I drilled and sized the fuel line fitting for the right tank after creating the tank so we could move the bender back out of the way. The process for the fitting was the exact same as the left wing, just the opposite side of the tank:
Picture of the top front of the left wing tank. I've laid out the location of the top mount fuel tank sensor and the fuel filler neck.
Both tanks clamped together, resting on top of the wing and awaiting parts for the fuel filler neck and fuel level sensor. These will be fitted before final weld-up.
Very pleased at how the tank assemblies turned out, hopefully welding and subsequent leak testing goes as well. Getting ready to order the fuel filler necks, fuel caps and the parts needed for the fuel level float sensors.
This doesn't fit under either the engine or avionics category, I guess it is part of the wings? Maybe under other......
Thanks for following along, stay tuned for more.
Happy New Year to my dedicated and loyal followers!
A bit of a slow start to 2022, but back in the shop for a few hours over the past few days. I'm still waiting on the fuel lines and fittings to come from the supplier, hopefully soon as I'd like to get them test fitted before I flip the wing over in the next couple of weeks to build up and fit the fuel tank in this wing.
While I wait for those to arrive I got the backing strips epoxied to the inside of the wing tip. EcoBond epoxy is spread thinly on both sides and left to set up for about 5 mins:
The 016 aluminum backing strip is clamped in place and left to set up. I leave these overnight and have no problem with them bonding well.
A test fit to the outboard wing reveals little trimming to be done. I'll need to confirm the measurements of the other wing to see where the other wing tip positioned for final fit and make sure this one is in the same place making the wings symetrical.
My push-connect unions came in from the supplier. If you are familiar with SharkBite plumbing fittings these work the same way. I'll be using these to connect up the pitot-static lines once the wing is flipped over.
Long time readers will recall the genesis of this entire project was largely credited to the mentorship of my friend Captain Barry Morris. When he passed away suddenly in Sepember 2015, I made it my mission to get working on this project and not wait for it to just come to me (see my earliest blog posts for more).
I've been in regular contact with Barry's widow, Linda Morris since his passing and we've shared many memories, laughs and tears. She gave me the honor of gifting me a damaged wooden propeller that belonged to Barry that he "acquired" and had cut down to a "trophy" of some sort. I wish he was still here and could share how this prop came to be, but somewhere in his adventures it came into his possession and I will treasure it forever.
For Christmas from Brenda, I was surprised to receive a hand made clock insert for the prop. Here is a picture of it installed. The words scribed on the face mean a lot to me, it is in a prominent position in our kitchen where I see it every morning:
Next up in the shop are fuel tanks and today I'm working on the design of strobe/position/nav lights for the wings among other things. Now that I have finalized the controller design, I want to test some higher power LEDs that I found on Amazon and see if I can really make the lights punch it out by boosting the voltage up. Also pondering lens design using clear casting resin - all in with experimental right? I'm NOT paying over $500 for what is currently offered on the market for lighting solutions.
Stay tuned, more to come.
Christmas has come and gone for another year, so I went to the shop for a couple of hours on Boxing Day. Today's focus was getting the lower wing skin riveted on, but I got a bunch of other things done or started as well over that afternoon and the next day.
I started by pre-setting the A4 rivets along the rib lines and lower skin stiffeners.
I'm purposely leaving the rear edge of the main skin un-rivetted as I still need to tuck in the trailing edge and I can't do that until I finalize the fuel, pitot and static plumbing. I've got fuel line on order (more on that in a future blog) so it will have to wait. Also in this picture the inboard nose skin has been fitted:
I sue Sharpie markers a LOT to make notes on parts as reminders, etc. In this case, I marked this section as "wait" so I wouldn't rivet the lower wing skin until I fitted the main strut pick-up angle. Can't add that until the nose skin is in place:
Here the strut support angle is in place on the lower wing skin, across the main spar and over the nose skin. I struggled a bit with the right wing deciding on an order of operations, but lessons learned there were a huge help here. First, get the rivets in that won't be accessible when the strut pick-up protrudes through from the spar:
First, the A5 rivets at the spar:
Next the pick-up angle is added and some of the A5 riveted to the support angle:
Next the balance of the A4 rivets through the support angle where required:
The balance of the A4 rivets in the support angle (which gets the A4 clecos out the way), followed by the balance of the A5 rivets into the strut angle:
The room to bolt the strut pick-up to the spar web doubler is very limited. To fit the strut pick-up, I carefully tied the nose skin up far enough to get underneath:
This gave me real good access to the spar web doubler angle:
The bottom two bolts in the picture face "downwards" once the wing is right side up. The top bolt i the picture is inverted to clear the nose skin once it lays flat. The bolt are just infer tight so far, I have enough access on the wing is flipped over to roll the nose skin over the nose ribs:
Strut pick-up assembly complete and line up looks perfect:
With the inboard nose skin now ready for final riveting to the spar, I primed the pitot-static tube porthole:
Masked off using wide painters tape and a recent Chritsmas flyer (now useless LOL):
While I waited for that primer to dry, I final fit and riveted the tie down ring:
Final A5 rivets into the main spar:
Forward jury strut attach angles in place:
Inboard nose skin attached to underside wing spar:
Porthole primed, ready for final drilling to A4:
Pitot static tube, final fit complete at the nose skin. I won't rivet this yet, need to wait for final plumbling of the nylon lines:
The nylon pitot static lines run parallel to the rib from the main spar, through the rear channel and inside the trailing edge to the wing root where it meets the cabin.
I started by drilling an A5 hole where the first line will come through the rear wing channel:
The nylon lines are 1/4 inch outside diameter, so I need a hole 3/8 inch for the right size rubber grommet that will prevent the nylon line from rubbing on the metal:
First grommet in:
Second grommet, offset from the first:
The grommets are a good fit with no pinching of the nylon lines. I'll be adding tie down points along the rear channel face to secure the line once I have the complete routing to the pitot-static probes complete.
Brought out the template for the outboard nose skin to prep the cutting of the nose skin where it wraps around the wing tip. Still have lots of trimming to the fibreglass tip, it looks like quality of this molding wasn't as nice as the right wing, but with a bit of sanding it should be okay. Also need to add the 016 reinforcing strips.
First rough cut of outboard nose skin shows I am on the right track. The challenge will be making this wing an exact copy of the other one (miror image).
Good progress and more to come this week. I've got a bunch of stuff to consider (fuel tanks/lines/guages being big ones) and wiring/lighting for the navigation, strobe and landing lights. Fuel line and fittings are coming soon and add to that I've got fuselage parts on order hopefully coming early in the new year. I also have a line on some real good used avionics I need to make a decision on soon in order to get them at a substantial discount.
The underside of the wing is almost complete and soon will be flipped over to fit the fuel tanks/plumbing once I get the parts and finalize the trailing edges and wing tip.
Thanks for reading along. I hope everyone is having a good Christmas break, more to come soon.
Been a while since my last blog. I was away from home for a couple of weeks on a work road trip. Managed to squeeze in some shop time one night before I left and a whole day after I returned.
Got the rear and front jury strut attach angles fitted and drilled:
Pulled the lower wing skin out of the way to match drill the lower trailing edge to the rear channel now that it is trimmed to the correct width:
Took the protective plastic off the outboard nose skin, deburred and prepped the underside for prime:
Same for the inboard nose skin:
Final drilled the rear strut attachment, bolt and riveted onto the rear wing channel:
Deburred and rivetted the flapperon arms to the ribs:
The 3rd flapperon arm will be final riveted once the trailing edge is in place - it leaves more room to slide the inboard trailing edge skin over the rear strut pick-up, a lesson learned from the other wing:
I decided to estimate where I'll need to run the nylon tubing for the pitot-static system. I clamped it in place approximately where it will sit and discovered the wing spar is in the way!
Can you spot the issue?
I have a couple of options. I could bend the tubes outboard and then run the lines through the lightening hole in the spar web, or shorten the two tubes a bit and pass the nylong through new grommeted holes I will drill in the web. I think I like that idea better, it will give more support to both. I'll wait until the pneumatic connectors I have on order arrive to see how much to trim.
Finished off the day by deburring and priming the lower wing skins. Also deburred the lower half of the wing skeleton, spar and rear channel.
Next up, fitting the plumbing for fuel (lines/fittings on order) and the nylon tubing for the pitot-static system.
Merry Christmas everyone!!
Good productive Sunday in the shop this past weekend.
With the JB Weld epoxy well cured on the pitot/static tube assembly, I was able to sand away some of the sloppy clumps and prepare it for priming. The bench top belt sander worked well for this when taking down slowly to the metal.
With most of the end clump of epoxy removed, I rounded the tip of the static port probe:
In order to prime the assembly, I needed to block off the pitot tube end and the small static port probe holes. I found a piece of steel rod and with a bit of electrical and masking tape on the end made a nice tight fit to prevent primer from getting inside the end.
Kind of hard to see in the picture, but I used some 3/16 inch drill bits in the static probe holes, then primed it all.
In no time, the primer was dry, so I flipped the assembly over and primed the inside tubes after taping off the ends where the pitot/static lines will attach:
Primed and ready for install on the wing, very happy how this turned out!
This picture shows the rounded static tip well. The scuff marks in the primer are cosmetic only and look worse from the camera flash. The inside of the tubes have been treated with Crown to protect against rust.
Also primed the front strut pick-up and support angle. These will get rivetted once the lower wing skin is done.
Next up was laying out the 020 aluminum for the outboard and inboard trailing edges.
Lengthwise bends using the 1/8" radius bending shoe:
The bending brake can only bend the aluminum so far, but does a great job of creating a crisp trailing edge radius:
A preliminary test fit onto the rear wing channel showed a need to trim a little length of the forward facing edge to ensure the distance between the rear channel rivet line and the trailing edge is exactly the same as the other wing.
To finish the bend to the 18 degree opening angle as described in the plans, I secured the trailing edge to the bench with a 1/8 inch rod running the entire inside fold. The wood shims are thinner than the rod so they don't crease the aluminum as it is bent flat:
A better look at the overall set-up. The wooden shims are wedged in place between the rod and the securing playwood which is screwed down to the bench.
A long board and c-clamps apply an even squeeze to form the trailing edge:
I needed to slot the trailing edge skin where the rear strut pick-up protrudes through from the rear channel. I marked the location by extending the lines forward when the pick-up was in place, removed the pick-up then transferred the location backwards to the trailing edge skin when it's in place:
Knowing where the slot needs to be laterally, I can created the slot based on the width of the pick-up (the narrow black rectangle represents what needs to be removed):
Two holes drilled at the end of the slot, then cut out the slot using the Dremel tool:
It worked perfectly, the slot is the perfect size (the slot on the right is for the flapperon arm which has been temporarily removed to make positioning everything easier to manipulate for fit-up):
Both trailing edges fit up and ready for A3 match drilling to the lower skin and rear channels. I need to run the plumbing for the pitot/static and the fuel lines before getting to much farther, but the trailing edge is straight and true.
Next up, taking the lower skins off for debur and priming, along with further wing tip fit up.
Thanks for following along as always.
Back in the shop today. Got back to work on the second wing, continuing with the fit up of the pitot static tubes.
I was going to leave the tubes braze welded where they join inside the nose skin, but decided it would be better to braze weld it on the outside portion as well to give it more strength. Flipped the tubes around and braze-welded the tubes on the outside portion of the plate:
To get the tubes in the correct position is a bit challenging The centerline of the static tube (the lower one when the wing is upside down like it is now) needs to be 64mm above the wing skin, but it also needs to the perpendicular to the nose skin surface and perpendicular to the wing spar. This ensures the air flowing across the wing enters the pitot correctly leading to more accurate airspeed readings. If the tube faces slight down/up or sideways to the relative airflow, that can induce airspeed indication errors.
I grabbed a short block of wood from the scrap pile and drilled a 1/4 inch hole close to the end of it:
Used the bandsaw to cut off the end of the block, giving a resting groove for the tube, then trimmed and sanded the opposite end so the block is exactly 64 mm long:
The concept was good, but very hard to make it stay still as there was no easy way to balance or attach the block to the skin and keep the measurements accurate:
Grabbed another board from the scrap pile and created a jig to simulate the wing skin surface.
Drilled a hole similar in size to the one in the nose skin to pass the tubes through:
I like using wood as a base for jigs because you can cleco things to them (I've done this in the past for things I need to duplicate accurately. In this case, it's just to simulate the flat surface of the nose skin:
The picture isn't in best focus, but you can see the concept. The tube is supported by the block which is secured to the wood by a screw from underneath. This places the tube exactly 64 mm from the "skin" and I can also confirm the tubes are square to the plate and parallel to the "skin":
I used a scrap piece of 016 aluminum to strap down the tube in the groove of the block. This holds the tube exactly where I need it and gives me the freedom to secure the tubes to the plate where the tubes pass through:
For years I've seen JB Weld on the shelf of the hardware store and never thought I'd have a use for it. After Ron recommended it as a way to bond the tubes to the plate, so I thought I'd give it a try. Brazing the aluminum plate to the steel tubes would be difficult as each material heats/cools are different rates and heating the joint up enough could compromise the strength of the brazing I'd already done.
JB Weld is very easy to use. Squeeze out a small amount of each part of the epoxy onto a piece of cardboard:
Use a small stick and mix the two parts together until they completely blend to an even colour:
With the epoxy blended, use the stick to apply around the joint and let sit. It takes about 4 to 6 hours to set up and another 12-24 hours to fully cure. It cures extremely hard and strong and can be shaped with grinding and sanding and accepts primer and paint:
I also applied a liberal amount to the end of the static tube which by design has the end plugged (it reads static pressure from the 3 tiny holes drilled radially along the length, perpendicular to airflow). Once the epoxy hardens, I will carefully grind this tip into a more acceptable aerodynamic point, probably a bullet shape or maybe just rounded off.
So of course after all those years of seeing JB Weld on the shelf and not thinking I would ever use it, I can now thing of dozens of uses!
While I Iet that set up and begin to cure, I turned my attention to the front strut pick-up angle. I remembered how I did the other wing, so was able to fairly quickly bend the angle to shape, fasten it to the assembly and drill out the 3/8 hole to match the strut pick-up:
Brought the second wingtip down from storage and did the preliminary cutting out from the mould and trimming the edges. Lots more to do here with outboard skins and nose skin before final trimming will be complete.
Started to layout the curve of the outboard edge of the nose skin. The templates I made are very helpful to make this wing an exact opposite of the other wing.
Thanks again for following along and special thanks to my girls Brenda, Caitlyn and Natalie for giving me the time on Saturdays to work on this dream of mine.
More to come.
Still working when I can on the left wing. I've found it challenging to get to the shop as regularly as I would like, but a little encouragement from Brenda to get moving on Saturday morning was a big help.
First thing I wanted to do was inventory and sort some of the partial sheets of rolled aluminum I have on hand. I've very close to having everything I need and certainly everything I will use in the immediate future.
Inboard nose skin installed on the wing. Critical to get it straight for drilling holes on the spar line otherwise the skin will roll over the nose ribs crooked, leading to wrinkles. A long board weighted down helps keep everything flat.
Used some strong twine to gently wrap the nose skin over and down, leaving more room beside the bench to drill the spar out to A3:
This time, before adding the nose skin, I roughed out the measurements of where the slot for the strut pickup, then translated that onto the nose skin:
I did the same thing on the rear channel where the trailing edge skin will need to be slotted for the rear pick-up:
Outboard nose skin added and rolled down like the inboard. This makes it so much easier to reach to the spar:
Attached the strut angle to the lower wing skin and where it extends out over the nose skin. In the picture I've leaned the strut pick-up approximately in place. This will be bent over to act as the doubler for the strut pick-up where it protrudes through the skin from the spar inside:
Here is a picture from the right wing which explains what it looks like completed:
The correct slot in the outboard end of the skin and the tie down ring in place. I'll wait to rivet it until the skin is ready for final riveting.
Strut pick-up slot cut and fit, forward strut pick-up in place awaiting fit up of the doubler angle:
One of the differences with the left wing vs the right one is the addition of the pitot and static tubes.
In simple terms, the pitot tube faces into the slipstream and passes that pressurized air entering the tube through a system of tubing to the instrument panel in the cockpit. An airspeed indicator uses changes in pressure in the tube to calculate the speed of the aircraft through the air.
The static tube measures atmospheric pressure outside the aircraft which is used by other cockpit instruments to calculate altitude and the rate of climb/descent.
Systems vary from aircraft to aircraft, mine is made of simple metal tubing, formed as per the plans.
First I needed to add a plate to the location on the lower nose skin where the plans define the pitot/static tubes will be:
In preparation to bend the plumbing for the fuel system, I bought these tube bending pliers:
The pliers were fantastic to bend the 1/4 inch outside diameter steel brake line for the tubes. The two tubes travel parallel to each other. The one on top is the static tube, the bottom the pitot (airspeed):
This is where things get a bit tricky. The plate needs a figure eight shaped hole for the two tubes where they run parallel. Once welded together, I won't be able to slide the plate off the tubes because they diverge at both ends:
Before welding the tubes together, I removed the plate from the tubes and used the hole to trace out a rough location for the hole in the nose skin:
The hole needs to be wide enough that when the tubes are welded together the ends can pass into the nose skin but still be covered by the plate. Corner drilled the proposed hole....
....then Dremel tooled the lines to create the hole. A bit of filing to clean up the corners and edges:
I taped the tubes back together with the plate and checked the fit in the hole - all good.
The static tube has three holes drilled around the circumference. The end facing into the siipstream is welded closed. Completed this way, the tube measures atmospheric pressure:
I included a photo of the drill bit (3/64") to give some idea of scale:
I cleaned up the tubes with Scotchbrite pads and again with a stainless steel brush. I used a couple of woodens shims to clamp the tubes in proper position relative to each other and actually remembered to re-add the mounting plate:
Gentle heat up of the tubes where they join inside the wing and brazed them together:
With both tubes brazed together I placed them back on the nose skin. I'll need to figure out how to position these accurately later when the wing gets closed up, but very pleased how they turned out. They get some JB Weld epoxy at the hole to seal them up to the plate and primed before paint.
Good progress this last couple of sessions. Next up, trailing edges. Plumbing for the pitot/static tubes needs to be considered soon as the lines that go to the cockpit/panel run through the rear channel and into the trailing edge spaces as does the fuel lines.
Thanks for following along, stay tuned for more soon.
Race - the answer is Race.(not sure at my current pace what place I'll come in, but still progressing).
Although things are still progressing on the plane, there isn't much to share that you haven't already seen. This wing is obviously a mirror image of the first, with very few differences that are yet to be addressed. I've also been busy with projects outside of the build which have kept me away from the shop more than I would like. Summer is coming to a close and winter is not far behind, so more shop time is likely (I hate the cold of winter.... maybe hate is too strong a word but whatever).
With the rear channel now in place and riveted to the rest of the skeleton, I took the upper skin off for debur and to check and rivet the main and nose ribs.
It pays to double check every thing. On the inner wing tank rib, I "figure eighted" a hole when back drilling the upper root skin. It's easy to do, just was very disappointed to make this mistake.
I originally planned to replace the entire rib, which would mean starting from a blank, forming the rib on blocks, cutting and flanging lightening holes, the works. Not to mention removing the damaged rib from the skeleton by drilling out the rivets, etc. In consultation with Ron, we decided a doubler L epoxied to the inside of the rib flange would be a suitable and easier repair. That took a couple of hours to make up, but the results are strong and acceptable - also much better than making an entirely new rib!
Drilled out the tie down ring and match drilled it to the nose rib:
Upper wing skins final riveted to the ribs. When I flipped the other wing over, I noticed the square tubing left scuff marks on the skins despite having masking tape on them. I decided to mask the skins where they will contact the tubes when this wing is flipped over to try and alleviate the issue this time around:
Flipped the wing over on the bench and squared everything up with a level (pic is before levelling):
With the spar now perfectly vertical and the skeleton evenly supported from below, I laid out the rivet line in the lower main spar using the shop LONG straight edge. Also rivetted the nose ribs to the spar:
Pulled a fresh 12 foot roll of 020 and cut out the inboard lower skin. Rolling it out on top of the skeleton it was nice to see a good square fit on the wing frame:
Flash forward a bit, the lower skin is in place, as are the flapperon arms and requisite slots in the lower skin:
The outboard lower skin was next.
Outboard lower skin complete with stiffening L. Trimming the end to match the wing tip will come once the wingtip is fitted:
All ribs and lower skin drilled out to A4 with the exception of the lower root rib:
Way back, I made up 2 root rib splice plates while I had a couple of scraps of 025. I put them away in my bin for when I got to the wings but apparently I lost track of them. When doing the first wing, I had forgotten them so made up the one I needed at the time. Low and behold today I found the pair I made way back when. Today I added the second one. That's the way it goes with scratch building and small parts I suppose.
Pulled the flapperons/skin support angles, slat supports/support angles and the root rib doubler from the skeleton, deburred them and cleaned them up for priming:
Grey self etching primer complete, these parts will be riveted to the wing soon:
Progress is progress, even if slow. Thanks Mr Tortoise for the valuable lesson.
More to come including debur of the lower skin and fabrication of the pitot/static probes. Thanks as always for following along :)
Good productive Saturday in the shop.
Finished fitting the upper root skin to the wing. As this is the second one of these I have to do, I knew what it should look like when it was done and the easiest way to get there.
The root skin it attached at the rear channel first. I used some tape to hold it down at the main spar so I could scribe a line where the tank rib doubler strip and root rib lines are:
Working from the rear channel forward., A3 holes/clecos following the scribed lines:
A3 the up-sized to A4. The reflection of the shop lights make this skin look crinkled, but it curved out really smooth and I'm very happy with how it looks:
Next was pilot drilling the root skin doubler as it extends over the first nose rib. I wish the root skin doubler on my right wing turned out this nice, but that's the value of experience.
Disassembled the rear channel for debur and prime:
Once the primer was dry, I reassembled the rear channel and attached it to the wing. Measuring everything up to ensure the wing remains square is an important step:
On the right wing, I did the bulk of the riveting of the rear channel off of the wing skeleton. This time I decided it would be better to do it all on the wing in position - this too was a better way to do it.
The centre section where the two rear channels meet is also where the rear strut pick-up is located. I didn't rivet here yet because I want to fit the lower skins and trailing edges first.
Another good Saturday done, 7 hours total added to the tally board.
Next up, nose rib debur, prime and rivet - then the wing can be flipped over to work on the lower skins.
Thanks for following along, more to come.
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Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.