With both the wings into going into storage, I added the fuel tank drain/test ports. I need to make sure that nothing can get into the tanks while they sit in storage, and the any openings on the wings, like the lightening holes at the root have been covered up with tape and plastic to prevent bird or mouse nests!
First time in a very long time the bench has been completely clear of wing stuff! Time to start laying out the fuselage skins.
Had a couple of minutes one afternoon after work to finish one of the horizontal tail fuselage bulkhead frames need for the fuselage:
The plans are a bit deceiving when looking at the them when scaled down from full size. Close attention shows that the four corners of the fuselage aren't actually directly straight - the fuselage tapers very gently from the back of the cabin to the tail along all four longeron corners.
I've been pondering this for a while and when I was at the Zenair factory in Midland buying my longerons last month, I asked Nicholas Heintz (Chris' son) what would be an acceptable way for a scratchbuilder like me to make the correct tapered curve of the skins (the longerons curve to match the skins and are pre-cut in the kit versions).
Nicholas said the taper is very subtle and I should just connect the measured points out from the centre-line as shown in the plans. As long as the taper is equal on both sides of each of the four fuselage skins, all would be acceptable, but the taper is important as it provides some longitudinal rigidity to the fuselage..
Apparently that's not good enough for me! I wasn't confident that each 500mm point would give me enough points close enough together to draw through to make the gentle curve. So I grabbed the plans and entered them into CAD, like a lot of the templates I've made.
CAD has a great "spline" tool that is like using a draughtsman's French curve ruler to average out the points in the plans to establish a smooth curve. Then I used tools within CAD to section each of the 500mm sections on the plans into 100mm smaller sections, then measured where the points along the curve so I could transfer this onto the aluminum. Enough points along this curve means I can connect them with a real French curve ruler and have my taper drawn correctly on the aluminum sheet.
Here is a snapshot of the fuselage bottom skin, half way through the sectioning process in CAD:
The fuselage skins are all 0.020 thick, with several doublers between the longerons laterally and diagonally to stiffen everything up. The bottom skin is laid out on the table and I used the long straight edge to draw the centreline from which the edge points will be measured:
I measured out each of the sections lines along the centre-line, then used a square aligned with the long straightedge to plot the section lines out the edge of where the skin will be. I soon realized that Nicholas was probably right, curves based on the 500mm sections would probably be enough, so I decided to divide the sections into 250mm sections instead. This is a good compromise and accurate enough for me to make the taper correct using the French curve ruler we have.
This picture shows the lateral lines drawn out from the centre - the circles are where the curve of the edge of the skin will be and the lines from circle to circle are the skin edges which will be trimmed later. From there, I laid out the lower hatch door opening (often called the hell-hole) and some of the other lateral lines for the stiffeners, diagonal "L's" and torque tube bearing channel (supports the control torque tube):
A 10mm line scribed inboard from the edge skin is the rivet line where the skin will be fastened to the longeron once the skin sides are trimmed. This picture is the tail end of the lower fuse skin.
The lower fuse skin is actually too long to fit on a full 12 foot sheet of aluminum, even if I "tilt" the lower skin outline on the sheet, so a lower rear skin is added - it becomes part of the horizontal tail "box" and further strengthens this part of the fuselage to support the tail structure. Aligning it on the centre-line at the proper location ensures the lower skin is the correct length from the cabin to the rudder supports. Here it is temporarily clecoed in place:
Z-channels are added around the sides and rear of the lower hatch. These still need to be trimmed, I just wanted a rough idea where/how they interact with each other and how the rivet spacing should lay out. The square of cardstock is a quick cut out for me to use to visuallize where the flap motor will mount - again for rivet spacing, etc.:
Cutting out the access hatch was fairly easy. I used the fly-cutter to shape out the corners:
Then connected the edges of the circles and cut out the hatch. Some filing and sanding to take care of some rough edges and the access hole is done. I'll make the hatch cover from some of the left over 020 of the top skin.
I finished (for now) the bottom skin. All the rivet lines are laid out and drilled. Before I cut the bottom skin out, I've rolled it back up as as full 12x4 full sheet. Much easier to store.
Returning to CAD, I sketched out the two side skins and the top skin - this time with 250mm sections. It worked so well with the bottom skin, this will be the path to obtain the tapered curves for the other 3 sides of the fuselage (these are snapshots from CAD, not scaled together):
The top skin is somewhat shorter in length than the bottom skin, so I can comfortably "tilt" it on the aluminum sheet to save wasting some of the sheet.
Same layout method as the bottom skin. This skin has a flanged hole near the tail - this is where the elevator control cables will pass through the fuselage into the vertical tail assembly. Cut it out using the fly-cutter. I'll flange it later once the skin out cut out form the sheet so I can clamp the flanging dies easier (can't reach the hole now):
A second hole is cut near the tail end. This will form the round end of the channel as laid out by the lines drawn rearward from the circle to the rear skin edge:
Now onto the part that has been keeping me up at night.
We don't have the ability to bend complex shapes such as the upper top channel shown below. It's a slightly leaning C shaped channel, tapered at the ends that forms part of the wing spar carry-through on the top rear of the cabin. It is made of understandably stout 063 aluminum and both the shape and dimensions are critical to ensuring the wings mate to the fuselage at the right angle and location. So I ordered this from Zenith and picked it up the same day as the longerons.
Problem is, I hadn't thought it through and asked them to provide the channel pre-drilled, as they would in a kit. What I didn't consider is how to transfer the holes to the cover channel and doubler that make up the other sides of the top channel to form the spar carry though box.
I could order those pieces too, but when I spoke with them, they couldn't guarantee they the holes in the other 2 parts would be an exact match to mine as they drill them together at the time of manufacture, and mine was a one-of ordered part.
What to do. Start looking at order of operations and see if I can match drill the holes somehow, while respecting the bends yet to be made in the other two parts.
I can access some of the holes at the end of the top channel where it is cut diagonally to match the cabin uprights, so I placed the top channel in the proper position of on the top skin, drilled/clecoed the accessible holes form above into the skin. With that done and the channel secured to the skin in the right location I then duplicated the remainng holes along the bottom of the channel (actually the top when the skin is in place) onto the top skin because I can use the strap duplicator before the other pieces are added and drill from below the table level:
Unfortunately, as well as that worked, several of the holes on the channel are the bigger A6 river size rather than the standard A5 in the rest of the channel. Here is the channel lying on it's back. The 5 holes grouped close together are the ones I'm taking about. I don't know if an A6 duplicator is available, but we don't have one. These A6 holes are not accessible from inside the channel either.
Time to get creative.
I bent a matching piece of 016 to fit inside the channel and long enough to cover both the A6 holes, two inboard A5 and the A5 hole outboard holes and clamped it in place:
Back drilling through the channel into the 016 (using clecos in the three A5 holes to hold it together straight) and A6 size in the other holes gave me an excellent template to transfer to the skin that will match the channel holes:
Template added to skin, secured with clecos in the existing A5 holes, then A6 holes drilled through the skin:
I added more holes in the template from the forward facing A6 holes so once I have the doubler and channel angle bent, it too can be duplicated without having the access from inside the channel:
Fabricated and drilled the upper baggage area rear panel support angle to the upper skin:
This angle won't change once needed, so I finished all the river holes, deburred it and put it back into storage.
Next up was fitting and predrilling the upper fuselage top doublers. These doublers are almost like the shoulder blades of the wing/fuselage junction which transfers the loads back over the fuselage longerons and upper skin.
First I lined them up on the top skin and used extended lines from the top channel holes and the longeron rivet lines. Once in place, I traced those same river lines onto the doubler and laid out the rivet locations as per the plan. The doubler actually fits onto the outside of the fuselage, but laying it out this way allows me to see the lines before drilling through the doubler and the skin.
Once I was satisfied with the layout, I drilled pilot holes in the doubler on the drill press in the require locations, but not where the top channel lays. Then I back drilled through the doubler in 5 locations to secure it to the skin. The rest I'll drill once the longerons are in place:
Both doublers in place, secured enough for the next steps:
Shifted the doublers to their proper position on the outside of the fuselage skin (remember, I'm working on the inside of the skin and it's actually upside down on the table) and clecoede them in place from above. Then I placed the top channel back in place and secured it from below using the holes duplicated earlier in the skin:
I drilled the forst A5 hole and the two A6 holes I can access at the end of the top channel, then removed the channel and marked the others through the skin and into the top skin doubler:
Removing the top doubler and finishing the holes on the drill press, proves the matching worked (for some reason the picture below seems to show the holes are out of round, but it must be a shadow from the flash as they are actually perfectly matched):
I've also been scrounging a bit online on various marketplaces, classified listings and forums. Scratch building makes you keen to grab deals when they come up and I've been scoring well lately.
Both Ron and I want to make epoxy resin castings for our navigation light lenses and strobes. One of the tools needed to cast clear lenses is a vacuum chamber which is used to de-gas both the silicone molding mixture and the epoxy itself.
I spotted this complete set on Facebook from a seller not to far away. She wanted $125 for everything but I managed to get it for $100 just by asking. It's really brand new, she told me she'd only used it a couple of times but couldn't handle the fumes, so she was looking to sell it to someone who could use it. I looked it up after I bought it and there is easily $400 worth of stiff here, so I was a bit surpised she was willing to sell it for so little.
I brought it to the shop and tried it. Ah. It's not working, that's why.
The vacuum pump appeared to be pulling lots of pressure at the end of the vacuum line, but nothing was jhappening in the pot. Originally I thought maybe the valves were bad or something and I would have to replace them.
When I looked closer however, it looks like someone let the some casting epoxy get into the vacuum port on the pot lid, sealing it completely over! A quick drill and clean out of the port, freed up everything and it is working like new again. Score! We can also use this to de-gas paint for the planes too.
On the Zenith website classifieds, I spotted a suitable airspeed and altitude indicator. Used, but in excellent used condition, clearly taken care of by the previous owner. $200 USD for the pair - Score!
Another Facebook marketplace find were these cable turnbuckles, cable swivels, and throttle cable. Less than $200USD for everything - Score!
Ron continues to look for some parts for his Continental O-200 conversion for the Aeronca Scout rebuild. He bought a Cessna 140 for the engine, but it needed a new intake spider which was cracked.
These are getting very VERY hard to find as they often get damaged during prop strikes and need replacing. New ones are available, but cost north of $800USD!! I spotted one on Facebook marketplace, contacted the seller and managed to get this good used one and a box of other intake parts for $100USD shipped! - Score! I've given it to Ron as thanks for all his help with my build and his kindness in letting me use his shop. That's the kind of karma that I believe we need more of in this world :)
I'm getting close enough now that I need to consider what I need for my Corvair engine install with regards to firewall forward stuff.
I ordered my Corvair/Zenith installation manual as well as the MOP (Maintenance and Operations Procedures) manual.
They arrived in my hands and I sat on the dock the following morning looking through them. This build is always on my mind, even in the quiet times :)
More to come, thanks for reading along!
My pressure sensors finally arrived! I'm stoked to experiment with these models as I believe they have the measurement resolution and electrical specs for my Arduino fuel gauge solution.
First up, unboxing and evaluation. First thing out of the box I was really surprised at how large they are. It didn't have any physical measurements on the ordering page, but I had the mistaken impression from the pictures online they would be somewhat smaller and lighter, similar to the 10psi sensor I ordered initially. the new one is larger, a bit heavier (not unreasonably so) and doesn't come with an integrated cable:
They will still fit my application space, but I'll probably need to consider some sort of mounting bracket to secure it with the fuel line. Overall build quality seems real good. Two sensors, exact same spec, just like I ordered - 1.5psi, 1/4 inch NPT thread connection, 0.5V to 4.5V output:
Looking closer at the electrical connection end, standard cable compression sleeve entry and what appears to be a small screw holding the cap on the top:
Backing out the screw I thought would allow the cap to come off to reveal the electrical connections inside.....
........but the cap is actually a full 4 prong indexed plug on it's own - the machine screw secures the cap/connector to the sensor body. I like that in the design!
Another nice design detail is the rubber gasket on the bottom of the connector, protecting the joint with the sensor.
The terminal block pops out of the cap to reveal good quality screw terminals which are numbered to co-incide with the pin outs on the lable of the sensor. #1 for 5V+, #2 for sensor circuit ground and #3 for output signal. There is a 4th terminal with a electrical ground symbol - I suspect this is for sensor body ground, but I'll need to test to be sure:
I do know I need a better and more scientific set up for true testing and calibration, but here's what I did tonight to try it out. I used the same poly tube and connections as I did the for 10psi sensor tested previously. I slowly added water to the tube (in the upright position) and monitored the sensor connected to the Arduino micro-controller. Using the same Arduino script as before, it is clear to me this sensor is not only much better suited range wise to what I need (1.5 psi vs 10psi), it also seems the output signal is much more stable. I suspect this output stability is part build quality and part correct range specific, but I'm happy where this experiment and my related theory is headed. The photo doesn't capture the graphed output on the laptop, sorry. I'll try and get some screen captures when my test method/system improves.
Still much testing to prove the effectiveness of this method for measuring fuel tank quantity to come. This is another example of stuff I'm learning on this journey :)
Happy New Year everyone!
With the Christmas holidays over, its time to get back..... WAIT!!
Failed well pump at home - replaced/repaired.
Failing clothes dryer - replaced.
Updated home network infrastructure.... started and functionally complete, but need to do more.
Check engine light on the car and new front struts installed.
Back to work... shift shuffle meaning an extra day of work to balance out the hours....yay me.
So, unfortunately the shop has taken a back seat for a couple of weeks. However, I AM BACK!
First up, finishing the centre section drilling out to A5. There is no question the number of rivets make this centre section solid:
Drilled out the rest of the elevator skin and nose skin holes to correct size:
Caitlyn came over with me to the shop on boxing day to shoot some pics of me working. Here I've taken the nose skin off the elevator to prep the outer hinge plate/pins.
The plates are made of 4130 steel, so it's important to centre punch them so the drill bit doesn't wander:
A bit of WD40 helps cool the bit, 4130 is a lot harder to drill than aluminum:
First holes drilled and plates clecoed in place - back drill to A3 then A4, then A5:
Nose skins back on, back on the bench with the stabilizer to start lining everything up, and...
.... uh-oh.... some interference between the nose skins and the centre support brackets. Apparently this is a common problem which is easily remedied by trimming the nose skin slightly and trimming the back the rudder support plate edges to clearance the nose skin as it pivots.
The fit of the hinge pivot point is still bang on - good!
Before pulling them apart again, I used a sharpie to rough out where I need to remove some aluminum:
While I had some downtime during a nightshift at work, I rigged up the trim servo and Arduino controller along with an example rocker switch. I had set this aside for several weeks but I wanted to refine my programming code a bit. This is a refurb laptop I fixed up and it took some more work getting the proper drivers for the Arduino installed amongst other things, but once I had those my new code loaded up perfectly and it looks like I've got the system nailed down to do what I want!
I brought the mock-up to the shop to show Ron but decided it would be a bit easier to demonstrate by mounting it to a board. I've added some spare LED lights to represent a cockpit indicator and a suplus limit switch to represent a momentary contact switch. I also added a really fancy post-it note flag to the arm of the servo to make it easier to see in a video.
Here is a short video describing the components of the system, my reasons for doing so and a demo of what it currently is programmed to do. Be kind, I'm no Martin Scorsese HA!
I've been thinking hard on how to bend the elevator trim tab. It's 025 thick and quite long. In addition, it has some complex tight bends that will be hard to do effectively on the bending brake, so I had to really think out an order of operations.
Like I usually do, I made up a test piece from some scrap 025 and used it to judge if the plan dimensions accurately reflect the true fit of the trim slot. Unfortunately, they don't quite fit - the gap is too wide to be covered effectively by the piano hinge.
I had previously cut a chunk of 025 to the flat dimensions called for in the plans. This the same dimension I used for my mock up piece. This wasn't going to work. The challenge is making the strip wide enough to account for the bends, the depth of the trim tab, the fore/aft distance in the slot and the overlap where they meet the hinge......hmmm....
After much thinking over breakfast coffee it dawned on me - why constrain myself to the flat part size listed in the plans. Why not cut the flat dimensions a bit wider or taller, then trim once I'm happy with the fit? I hate wasting aluminum in this way, but if I oversize the flat dimension enough to clearly cover the trim tab and enough to make use of the cutoff for something else, there won't be any worse waste.
At minimum, I'll salvage the cutoff and my original flat piece for other things yet to be fabricated.
First bend is the small tab at the hinge joint. The bender does good work on this, but can't bend far enough closed on this radius, so I had to bend it down further by hand. Fastening it the bench and leaning on it with a 2x4 worked. Next I bent the lower angle on the bender - this one is much more open so it worked as expected.
I placed the sheet in the approximate position in the trim tab slot. Width is a bit close will trim it down a bit to avoid any interference with the trailind edge. It''s clear from this picture the sheet I cut is well wide enough to cover the return bend back to the hinge.
Next I started fitting the hinge. The key here is to align the hinge left to right to take best advantage of a full barrel at each end. The barrel of the hinge alse needs to fit snug up against the trim spar. I used a small spare piece of hinge to mark out the correct length and it fits perfectly to the spar laterally.
On top is the spare hinge, length marked in green and my new hinge below it marked in red where I want to cut it
A chop saw makes quick work of the folded hinge, cutting though it evenly and easily. For the next step I pulled the pin out and ground down one side of the hinge arms to accommodate the safety wire required at each end to prevent the hinge pin from working it out - that would be bad!
To allow for safety wire, the hinge pin is slightly shortened to be just long enough to reach the last barrel at each end.
I remembered someone online suggesting using the bench grinder to slightly chamfer the rod ends to make sliding it back down the barrels easier. Just a small thing but made all the difference when reassembling the hinge several times over the course of this work. I also plan on using similar hinge to close up the engine cowling which will be open and closed more frequently - more on that later.
I flipped the elevator over again. When I was drilling the elevator skin, I didn't drill the holes where the skin meets the trim spar because I was waiting to see how the hinge would fit. As it turns out, this was a good idea, it saved me having to drill twice. I marked out the 40 pitch hole placement, placed the un-drilled hinge between the skin and trim spar and drilled it out to A3 (picture is after layout hinge pin not placed as of yet).
With the hinge apart again, careful drill of a small hole through the last barrel at each end to thread the safety wire when final assembly of the trim tab is complete. In this picture, I've already drilled out the 40 pitch A3 holes on the spar side of the hinge. Folding it over on itself, I marked the holes though to the trim tab side of the hinge (black marker dots on the left), then used this as a centre line (black) for plotting my holes on that side. I decided to offset them 20 mm from the spar side (blue tick marks)
Flip the elevator back over for viewing and dry fit of hinge to confirm safety wire hole is accessible AND viewable, both for installation and for routine pre-flight checks. From here I removed the hinge again and drilled out the A3 holes on the trim tab side of the hinge as marked.
With the bend width confirmed, I used the bender to create the trailing edge bend. It's tight and the bender can only bend so far over. From here, a 2x4 it used to lean on it and bend it further down to match the first. This picture clearly shows the long side of the trim tab will extend well beyond where it should - just like I planned.
With it close to coming together I flipped the entire thing over and secured it to the bench. This gives a much better view of the planned overhang. A quick sharpie line down the length gives a good line for trimming away the excess.
I drilled both ends of the trim side of the hinge to the trim tab and one in the middle for good measure. With it clecoed together in these three spots, I ressembled the hinge halves, clecoed it to the spar/skin side. Next, I proceeded to drill the rest of the trim side of the hinge to the trim tab using the previously drilled holes as a guide.
Took the whole thing off the elevator (again) and used the duplicator to match the holes on the overlap trim tab skin. I love this tool!
With everything clecoed together again, I checked the movement - nice and smooth and no binding.
With everything good, drilled everything out to A4 final size
Voila! (gratuitous happy moment capture)
With a few more minutes to spare, I decided to put everything on the bench again and line it up. Before doing that, I made the modification to the centre hinge plate that will allow the elevator nose skins the room needed to move up and down. I also trimmed the nose skin slightly to avoid any interference with the centre hinge support bracket.
With everything lining up and measured correctly, and confirming the whole assembly is flat and level, I marked out where the centre hinge bracket meets the elevator hinge spar bracket. With those marked where they meet, I took them off their respective assemblies for drilling.
I started with an A3 hole which will be enlarged to the correct size next. Holding it together with an A3 cleco, I confirmed they won't interfere when the elevator pivots up and down.
I stopped here, because when I was reviewing the plans, I have concerns about the size and type of the bolt used as the hinge pivot. The plans call for an AN3 bolt and vinyl insert lock nut. Not only does this seem awful small diameter, I believe it would be wiser to up-size the bolt diameter to an AN4 bolt and use a castle-nut and cotter pin to secure it. This mod is an improvement, I'll have to do some research what size bushing that will require.
Very happy with what I've accomplished so far. Next up is finishing the elevator/stab connections and fitting the servo and trim actuator rod.
Thanks for reading :)
The next sub assembly to do is the elevator. This is the trailing edge of the tail and it's primary function is to control pitch movement for the aircraft in flight. The initial assembly of this structure is somewhat less complex than the horizontal stab, but as always just as critical to get straight and square.
The nose, tip and rear ribs I formed fit almost perfectly and with a bit of trimming squared up the spar really nicely.
Being able to interpret the plans is becoming more apparent as I progress through this build. One item missing on the plans is the distance from the elevator spar to the elevator rear support channel seen below. The builder is left to decide where this fits. From what I can determine, the placement is designed to be back far enough so the flanges on the support channel are equal in height to the inner rear ribs. This would make sense as the skin and elevator hinge assemblies attach here. Front to back spacing is held temporarily in place with tape, squaring the whole thing up proved to be a bit tricky but I got it done without too much issue.
I had some discussion with Ron at this point, as I wasn't happy with the rigidity of the elevator assembly. I know that things will square up and get stiffer once the skin is on, but the assembly seems a bit lacking in structure at the middle where all the force and weight is acting on the elevator in flight.
Ron suggested I make a small modification that he is doing on his 701 builds by adding a 016 gusset plate across the top and bottom of the elevator centre section, extended out to the spar.
I liked the idea and set out to make the suggested gusset plates. Even at 016 thickness this will strengthen the centre spar of the elevator without causing undue problems adding the elevator skins.
I've drilled them out to A3 and will wait for A4 holes once the skins are on. One on the lower side....
...... and one on the upper side:
The last pieces to be fit on the elevator spar skeleton are the tip ribs. It's a bit of a juggle to get them in the exact right position, but they fit perfectly. Figuring out the order to drill them and the attachment angles to the spar was fun, but I got it done. A pair of wide neck welder's vicegrips are excellent for holding things together for drilling (note the protective masking tape on the pads to avoid scratching the aluminum):
Here is a picture of the elevator tip rib clecoed into place. The final rivets here are four A5 rivets which also hold on the outboard elevator pivot pins. Ron and I are going to weld up enough sets for each airplane being built and the holes will be matched with the A3 pilot holes I've drilled here.
As mentioned in my previous blog post, I'm considering options for a system to control the elevator trim tab. The plans call for a Ray Allen trim actuator and digital trim position indicator for the cockpit. But at $400+ I'm exploring alternatives, including substituting in a giant scale RC servo.
The Ray Allen system is spec'd to provide 40 pounds of linear push/pull force. Current metal gear RC servos are more than capable of meeting or beating that spec and with a bit of microprocessor power and programming are an attractive alternative. The whole replacement system from front to back including servo, a cockpit indicator and voltage regulators will likely be less than $100. The question is how?
Welcome to the world of Arduino, a programmable microprocessor board based on the AT328 chipset. With a bit of time, I believe I can use the Arduino to not only control the trim servo but provide failover support and control correlation. In addition, I have many options for how I want it to display in the cockpit, from a simple bar graph LED to a more intuitive graphic display. Only imagination limits me here. I',m also considering an Arduino board for controlling LED navigation lights and LED strobes.
So what does an Arduino processor look like? There are several models of boards all with different strengths and weaknesses, but most of either are related to what the board is capable of providing. I want the board to be simple to use but small for space considerations behind the control panel. For my prototype and likely final design, I've settled on the smaller sized Arduino Nano for the trim system:
I went on Amazon and ordered the Arduino Nano board and the associated mounting pins. I was able to find a 3 pack that included the unsoldered breakout pins. My plan is to use one board to prototype the trim system, one board to make for the airplane (wire soldered to the board) and one spare (in case one decides to poof into blue smoke if I screw up). I also ordered a voltage step-down board (top of picture) - the trim servo operates on 6 volts, so i needed a way to power it from the 12 volt system:
The easiest way to prototype and learn how to use the Arduino board, is to mount the pins on the breadboard, then place the Arduino on the pins. From there careful soldering each pin of the Arduino:
The Arduino is supported by a large online community of programmers, experimenters, robotic designers, musicians and others. It's simple but powerful programming language is easy to learn and because it is "open source code" based, there are literally thousands of example projects to build from and modify. I won't get much more into it here, but if this interests you, check out https://www.arduino.cc/
After getting everything together, I powered up the Aruduino from the USB port of my laptop ..... IT'S ALIVE! (I guess it's a stretch to consider that this might count as the first "power" my aircraft has had - I'm such a geek!)
After a bit of fussing around with loading up the correct USB drivers so that the Arduino programming application on the laptop can talk to the board, I uploaded my first "sketch", (the Arduino name of a coded program that instructs the board what to do). In this case, I added an LED and used the basic "Blink" sketch which tells the board to blink it's on board LED light
Again, I know this sounds geeky, but it's really cool! I messed around with the sketch and changed the blink rate and patterns and uploaded it again to see the result. I've got a bunch of learning to do, but a work colleague sent me some links to YouTube instructional videos which I'll work through and learn what this board can do.
Well, that's it for tonight. Back to the shop Thursday night to work more on the elevator. Got to finish the centre section, the elevator upper/lower control horns and start looking at how the elevator trim gets mounted. Got some disassembly, deburring and priming to do as well.
Thanks for reading, more to come :)
Been away from the shop a bit. Christmas with the family, shopping, work etc. There are important things in life besides airplanes I suppose :) That doesn't stop me from doing reasearch. Okay, you can call it browsing if you like.
I wanted to share a website I found called experimentalavionics.com
One of the biggest decisions to be made with my build is what avionics I want in my panel. This of course is guided by the three points of mission, cost and simplicity in that order, although they aren't mutually exclusive either. Simplicity generally leads to lower cost. Mission needs vs wants can also directly influence cost up or down. With a bit of work, the following items can be built very inexpensively, with off the shelf parts and instructions found online.
My aircraft mission is simple enough. I don't need to go fast or high (the Zenair 750 isn't pressurized nor is it a speed demon) and I won't be flying IFR (instrument flight rules). I do want good communications (it's actually what I do for a living!) and the ability to navigate outside the normal ATC coverage areas to some of those good fishing/camping spots.
I'm using a converted Corvair automobile engine. Instrumentation for this is simple too.
The idea of building my own EMS (Engine Monitoring System) from open source electronics/software fits both my budget and interests in learning. I have learned enough electronics skills over the years to build it (thanks to Mom and Dad for starting my learning in basic electronics by buying me this when I was a kid). Whether this becomes my primary engine instrumentation or a back up to the traditional analog engine guages will be decided later after I do some more research. It might look something like this:
A nice, easy to read display suitable for the 6 cylinder Corvair engine. The bonus is how much panel space I'd save and the ability to datalog the information for testing mods or diagnosing trends. Alarm annunciators (flashing warning lights or audio) can easily be added for any parameter that goes out of range. Cool!
The other panel items such as primary flight instruments (altimeter, VSI, etc) require more thought. I like traditional instruments for their familiar simplicity. For the same reasons as the EMS, a EFIS (Electronic Flight Information System) has an intriguing draw, but I'll likely have something like this as my backup instruments:
Again, easy to read, simple and space saving. 6 instruments and a clock all in one place.
A couple of cons that I'll need to consider are temperature operating range and failure modes. It gets real cold where I'll be keeping the plane when it's built (unless I win the lottery, then it's heated floor hanger all the way!)
As for failure modes, how comfortable am I putting all indicators in one place, where a single failure may result in losing everything at once.
The website that I linked above also includes preliminary discussions on intercoms for pilot/passenger communication and a WiFi based AHRS (Attitude Heading Reference System) that could link wirelessly to a tablet for navigation. Perhaps someone will adapt the AHRS to be an inexpensive ADS-B out module!
Lots to think about...
Happy New Year everyone :)
I've shared my overall plans with many people over the past couple of months. It never hurts to put word out you are looking for something. Sometimes it pays off, sometimes it doesn't, but either way everyone ends up learning more or less as you go.
Got a call from a buddy who came across what he thought might be an airplane throttle assembly:
Turns out it is a throttle assembly, but for marine applications. I'm thinking it's for a very large twin engine boat with adjustable pitch props. Close, but not what I need.
Next, I got a call from another buddy at work who tells me he has a bunch of "on the way to the trash bin" stuff he thought I might be interested in.
I grabbed a box of stuff from him that appears to have some sort of bench testing equipment for strobe light assemblies. Among the junk were two strobe power supplies....
....and five of these strobe heads:
Our employer doesn't use this older technology any more (everything now is advanced LEDs), but this could work very well for me and my build.
I wired up one of the power supplies and connected 2 of the strobe heads. In my shop they are almost blindingly bright and work in quad-flash pattern, very cool and would be excellent on the wing tips (the video doesn't really capture the brightness well):
My only concern is the amount of power that these older types of strobes draw and how much they weigh compared to self contained LEDs, but when something is scrounged for free, it's hard to turn down. If I decide to switch to LED lights during the build, I can always donate (pay it forward) to my Volunteer Fire Department (I do their emergency light installs anyway).
Onto the shelf they'll go for now until I'm ready.
On another "scrounging" note, Dad's got his contacts in the old car world on the prowl for a Corvair motor.
Yes, scrounging is worth it and all part of learning :)
In order for this project to come together, I'm planning on building in sections in order to keep things economical. Overall I'll be spending a fair amount of money, but by doing things in stages, it will keep me from being overloaded by debt.
I figure if I'm going to build and learn as I go, might as well spread the dollars over time as well.
To that end, I've broken the project into several "sections" and within those there will inevitably be sub-sections.
I've decided on the type of airframe I want (high wing, side by side). It will most likely be buying something that is a complete fuselage, tail section and wings. Whether that will be fabric or metal or fiberglass or a combination of 2 or 3 is yet to be determined. Tail dragger (conventional) or tricycle gear is also a consideration.
This will be largely dependent on the airframe, however the key here will be lightweight materials with a eye towards function and comfort.
The key here will be simplicity. For the type of flying I plan on doing, I really don't need much more than what is required for basic visual flight rules.
Now, I'm the first to admit that I am a gadget geek, easily distracted by the latest and greatest electronic systems and gizmos. Unfortunately, there is a big correlation between fancy and expensive. Surely some electronics add to simplicity and by combining several items into one do-all display there might be some money savings, but I'm not sure putting all my money into a single system makes sense. If that single system fails, it will be costly to repair or replace, where an individual component is easier to diagnose and replace where necessary without upsetting the entire apple cart. Perhaps once I'm up flying I can take a look at upgrades, but for now I'll stick with tried and true simple analogue stuff. (Unless I get a deal I can't refuse!)
In my next post, I'll talk about engines, a really big topic.
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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.