Odds & Ends

So it's been a while since the last update. Things are going well, but slowly. We've been working on sanding the inside of the cabin cover, installing conduit along the front "A-pillars" and "B-pillars", and filling in the voids with spray foam to then cover with fiberglass. I'm also trying to come up with the desired shape for the overhead switch panel, which will contain all my lights and dimming controls. I received my switch and terminal order from Digikey the other day, so I took a piece of scrap aluminum and quickly made a (very) rough mockup of what I had envisioned for the switch panel:

Overhead switch panel, v0.0.1

It came out "okay"... I think there needs to be a bit more room vertically between the dimmers and the switches, and also maybe just a smidge more space between each toggle, although I can live with it as-is. The idea will also be to have both the upper and lower edges of the panel curved, to better fit in the given space and give it kind of a more elegant look. At least that's what I'm going for-- it may very well end up looking like some kind of super-cheesy clown smile instead. We'll see.

I need to figure out how to illuminate these too. Right now the thought is to make a piece of clear acrylic that is painted a solid opaque color, and is then etched to allow light to pass through for all the legends and graphics. Another option would be to get a panel made from a place like engravers.net and backlight them with LED's. Although I like that idea (and I've seen some really sweet-looking panels made this way), I'd like to first try the acrylic method and see how far I can get. This will be on a growing list of back-burner projects that I'll get to, eventually.

Continuing on the electrical side of things, I also received my order for 12V accessory plugs. I kind of "splurged" on this and went with the VW/Audi parts that I've seen discussed on the forums. They're pretty slick-looking-- they have a spring-loaded door with "12V" marked on the front, and should provide a nice finishing touch to the interior when it all comes together. I'd take a picture, but one of the parts I received was incorrect and I'll need to exchange that out before I can move forward on this. There will be a total of three outlets in the plane: one for each of the two front passengers, and a third in the middle for the back seat.

I'm also working on preparations for the avionics. Specifically, I'm drafting all of my own wiring diagrams for the plane using the program Kicad, an open-source schematic capture and PCB layout program I've used for quite some time on a number of different projects. This is of course BY FAR the biggest of those projects, and it's going to take many weeks (if not months) to finalize a wiring diagram before I can actually cut, strip and crimp my first wire. The diagram will be comprehensive in nature and cover all of the avionics interconnects (of which there are many hundreds) as well as ship's wiring for things like lights, trim, flaps, etc etc. It's a fun task (yes, I actually enjoy this stuff) but it's also very tedious and does take a long time. It also has a tendency to make me cross-eyed after a few hours of reading through the thousands of PDF pages of install manuals and datasheets, trying to figure everything out. I'm getting there, slowly but surely!

Alright, I've talked enough. Here's a few pictures of many of the other accomplishments made this last week:

Rigged up the GSA28 pitch servo, and installed the optional Van's RV-10 ADAHRS tray to hold another GSA28 servo for the yaw damper. Fabricated a bracket to hold the yaw damper bellcrank, centered behind the elevator bellcrank. I'll probably re-make the ADAHRS tray itself out of thicker material and extend it forward slightly so I can also mount my GDL39R ADSB box. I also re-made the yaw damper arm into a more "boomerang" shape that has slightly different geometry that will work better with the movement of the rudder cables. I'll make a full post about the yaw damper and all the parts used to construct it once it's finalized.

Installed the Tosten stick grips... yay! I may cut another bit off the sticks to bring them down just a tad more. I started with them in a little high because... well... you can always cut more off but it's real hard to make them taller again!

Lastly, a quick montage of cutting out the rear NACA vent holes. Thanks to my friend Derek for stopping over and taking some of the action shots :-)

Traced the front NACA hole onto a piece of Lean Pockets cardboard, cut it out, and then traced it on this location in the aft fuselage skin. The vertical line shown is 10" back from (and parallel to) the seam between the mid fuse side skin and the tailcone, with a centerline drawn between the two rivet lines.

Me getting started with the cut using a Dremel tool

Cut almost done...

After a bit of filing, it looks great! Just the same as the holes in the front... woo!

That's it for now... until next time!

Happy 2016!

Man, it feels like I haven't posted an update since LAST YEAR. <groan>

Well, we've made some forward progress, but not really anything too terribly note- or photo-worthy. Additionally, I've been working on a side-project in the garage, swapping a transmission out of my old '77 Impala for one that has an overdrive in it (TH200 for a TH200-4R for all you gearheads). It's kind of tough doing a tranny swap working around all the airplane parts that are in the way, but hey that's life I suppose. It's almost done now, just have to figure out the necessary modifications to the crossmember. Anyway, as for work on the plane itself, the doors and cabin cover have come back off, and this allowed us to tie off a number of loose ends that remained on the fuselage itself. Namely:

• Completed securing, attaching, and tightening all of the fuel system components. Now the only part of the fuel system that remains are the connections to/from the tanks and of course FWF.
• Completed assembly of the control system, including measuring the pushrod lengths for the elevator controls and safety-wiring the appropriate rod ends. Fabricated a small "washer joust" out of 0.032" aluminum, drilling a 7/16" hole at the end, and then sanding the end off until only half the hole remains. This way you can push washers in between the different control system components as necessary without fumbling around with your hands.
• Attached nutplates along the mid fuse longerons by the rear seat area. This was a leftover task from the "access covers" section because I had experienced significant difficulty setting rivets in this area. They are at kind of a funny angle and I didn't have anything that seemed to work to buck these. Ultimately, I was able to succeed using a swivel flush set and an array of different bucking bars.
• Swapped out all the hardware attaching the rear seat belt anchors in the tailcone with stainless bolts and custom stainless cables. This is a recommended procedure for any ferrous metal located within about 3 feet of the magnetometer, per Garmin's instructions. I had previously attempted to do this, but had a terrible experience with galling and broke a number of bolts. I was able to succeed this time by lubricating the bolts first.
• Installed a few of the access covers and began test-fitting some of the Aerosport interior panels that I have. It's cool to get a glimpse of what the interior is going to look like!

So basically, the fuselage is getting pretty darn close to "done" status. Items still on the "to-do" list include rudder pedals (still holding out for some Control Approach pedals... it's not the funnest waiting game in the world but I figure as long as I have other stuff to work on we'll keep dragging it out) and dimpling/riveting the upper forward fuselage, which I'm going to lump in with work on the panel. Hopefully, we'll be able to get started on the panel sometime soon too! Still need to make it up to the Minneapolis area to pick up my avionics from Stein. Of course we can have them ship all the stuff but I thought it would be fun to get up there in person and pick it up (cost would be about the same or even a little cheaper than shipping with insurance). It seems like the weather has been conspiring against us making a flight up there for literally weeks now! We may have to just break down and drive up there. Maybe as a test drive in the Impala once the tranny swap is done... hmmmm.

Other than that, the work that remains now is to finish up the cabin cover, which mostly involves fabricating the overhead console, and get it final-installed on the fuselage. After that happens, we can finish with the doors, and then we can proceed with the rest of the finish kit items. Stay tuned for all that!

Interior Paint #2 - Section 39 Begin

Started off Saturday by stripping all the paint off the firewall, using a bit of Rustoleum "Aircraft Stripper" and loads of acetone on a paper towel. This was one of those lessons learned the hard way: Spend the time up front masking off the areas you don't want to paint so that you don't have to spend hours later on stripping it all off. Ugh. Oh well, in the end it all worked out.

All this paint stripping got me thinking: how much smoke really comes off the paint in the event of a fire? I've heard rumors that it creates thick, acrid, toxic smoke and can really make a life-or-death difference in the outcome from an in-flight fire. That was enough for me to take it seriously and strip it off. But, the engineer in me wanted to see exactly how much smoke comes off of this in a fire. So, I grabbed a scrap piece of aluminum that had been scratched beyond usability while installing the rear floor pans (remember my method for inserting them?). I had a love-hate (mostly hate) relationship with this particular piece of aluminum, so I was happy to spray it with some Rustoleum Hammered Black and take the torch to it. Here's what I saw:


It actually didn't smoke nearly as much as I thought it would! And the smoke didn't really have too much of an acrid or toxic smell. Not that I'd intentionally breathe the stuff, but it was a bit of a relief that it didn't blow up into a thick plume of nasty smoke or anything. Good data point, I guess. I still went through with stripping the paint off the firewall though, because it can't possibly hurt.

Once the firewall was stripped, I was able to mask everything again properly and spray another coat of paint in the areas that needed it. I went through the predicted two cans and left it to dry. Now... on to Section 39!

Whoa whoa whoa, Section 39, you say? What happened to 36-38? Well, I wanted to get started on the brake lines (36) but before I could do that, I wanted to make sure there would be clearance for the parking brake valve to go under (or at least near) the elevator control linkages, which are assembled in section 39. Additionally, section 39 is the first part I can actually work on and not need to be inside the fuselage, where the paint is still drying. So, off to make some aluminum control rods and brackets:

The F-1089 Elevator Pushrod

In total, I made three pushrods today: the F-1089 pictured above, the F-1090 mid-fuse pushrod, and the F-1091 pushrod that goes in the tailcone (plans in section 11 from the emp kit)... over 13 feet of pushrod in total! The next step was to final-drill and assemble the F-1063 Elevator Idler Arm, which unfortunately I didn't take any pictures of. It was a fairly straightforward piece to assemble. After that, I drilled the control sticks, which went fairly well too:

Drilling the control stick and pivot base

Not bad! Cruising right along in Section 39. Also, I was able to temporary-install the WD-1010 control column and figure out how much room there will be for the parking brake valve... looks like we'll be good to go for that! Will have to custom-make a mount for it and get it situated, will post pics of that later. Until then, more watching paint dry!

Section 34 Complete - Oil Cooler Mount - Interior Paint 1st Coat

Busy weekend! Started off Saturday morning attending a EAA Young Eagles event in Tipton, IA (8C4) and providing some ground help marshaling planes and escorting guests around the ramp. We had a great turnout, and it was awesome to see so many people from our chapter (#33) present. Two certified aircraft showed up-- a Mooney and a 172-- in addition to that though we had 5 experimentals including 3 Long-EZ's and 2 RV's giving rides! Very cool to watch our chapter pilots do what they do best in some gusty crosswinds at an airport that had some fairly challenging and wind-jumbling trees and terrain. Smiles all around!

After that though, it was time to get back to work and finish up the last remaining part of the baggage door: the F-1031 frame. My idea was to install a micro switch inside the frame, and put a small access cover in place of the original striker plate that would normally be there. After taking a few measurements and marking off the piece, I ended up with this:

The F-1031 Upper Baggage Door Seal Channel after installation

I don't have a pic of the cover plate or the micro switch, but the switch is attached to the cover plate and has a small steel wheel that protrudes out the back side (inboard side) of the channel. When the baggage door is closed, the latch catches on this wheel and pushes it in flush with the channel, activating the switch. This way, even if the door is fully closed, but the latch isn't latched, the switch will still indicate that the cargo door isn't properly closed. Should work pretty slick!

That puts an end to Section 34... yay! Before moving on to interior paint, I decided to assemble and install the oil cooler mount that I had custom-modified a few weeks ago to accept a larger-sized cooler. It went fairly well, although a few of the rivets along the top were fairly difficult to access. I ended up having to install just the top flange by itself to the firewall, allowing me to bend it down quite a ways to access the top row of rivets, and then assemble the rest of it as it got attached to the firewall. The resulting product looked great!

Custom oversize oil cooler mount, final installation - L side

Custom oversize oil cooler mount, final installation - R side

EDIT 11/1/2015: I think I may have messed up. Now that the finish kit is here, I see that the engine mount will actually get in the way of the larger oil cooler. I may have to redesign this mount from scratch, we'll see. Keep looking for updates on this.

The next order of business before we start bending brake and fuel lines is to paint the interior. Most parts of the interior will be carpeted or upholstered anyway, but the idea of painting the interior is to give the underlying structure a kind of consistent "base" color so that you won't see any unpainted surfaces in all the little nooks and crannies that won't be covered up. I've decided to go with a simple and inexpensive rattle-can paint, Rustoleum "Hammered" Black. The hammered pattern should give a nice look and spray on relatively easily.

I spent about an hour or so masking off all the parts I didn't want to get paint on, and in retrospect I think I should have spent even more time. More overspray got inside the tunnel and under the front seat than I had anticipated, which isn't a huge deal but it would have been better if I could have kept it brighter white. I may try and repaint it white or leave it alone, we'll see. Also, I never masked off the firewall so it ended up getting painted too. Not sure how I feel about that, we'll see how well it adheres to the stainless.

The first coat took 4 cans, and came out relatively well. It got a little blotchy in a few areas where I started to run low on paint, but I'll wait the recommended 48 hours and throw another light coat on. I imagine 2 more cans ought to do the trick. I'll also need to paint a number of other panels off the plane, so I'll probably need a total of maybe 4 more cans. Here's what it looks like so far:

Aft interior section after painting first coat

Forward interior section after painting first coat

That's it for now! We'll give this first coat 48 hours to cure and then try and shoot a light second coat over it and see if we can fill in a few of the light spots. Stay tuned for that!

Baggage Door

Got the baggage door strut installed tonight! After measuring open and closed distances, I fabricated some mounting brackets, riveted the inside door skin into place, drilled a couple holes and installed some #8 machine screws purchased in the "aviation aisle" of the local home supply store. The resulting setup looked like this:

Baggage door strut laid into position (mockup, not fastened yet)

Closed eye-to-eye distance of 5.5"

Open eye-to-eye distance 9-1/8"

The geometry came out great! To attach the strut on the airplane side, I ran a 2" long #8 machine screw down through the F-1034B/F Seat Back Braces and cut some leftover aluminum tubing to use as a spacer between the two halves. You can kind of see it in the first photo above. After temporarily installing some washers and nuts, I was able to verify the proper movement and latching of the door, which seemed to operate perfectly!

There's just one problem.

Whoever posted in the forums that they used (and recommended) a *20-lb* force gas spring is either considerably stronger than I am, or completely insane. 20 pounds doesn't seem like a heck of a lot, but rigged up in this manner, it is WAY too strong. When you pop the latch, the baggage door jumps open and basically punches you straight in the gut if you're not ready for it. If only I had the camera rolling the first time I opened the door, all proud of my work.

So, I'll be ordering a different strut from McMaster with a 5-lb force rating (#9417K6) as well as returning the bracket that I had originally ordered. The bracket was a good idea, but being relatively large and made of steel, it was way too big and bulky to really use on the baggage door. It was much easier (and cheaper) to make my own bracket out of aluminum angle.

Last order of business for the baggage door: Fit a micro-switch to the F-1031 Baggage Door Seal Channel. Hopefully we'll be able to knock that out this weekend, and finally get around to painting the interior too!

Baggage Door

Happy Labor Day! Well, this turned out to be an "interesting" 3-day holiday weekend for us. We went to Des Moines to attend our friends' wedding, but unfortunately we got our dates mixed up (100% my fault) and thought the wedding was on Saturday instead of Sunday. It turned out that there was also a different wedding taking place at the same time and location on Saturday, which we of course ended up at, all dressed up and ready for a fun night. It slowly dawned on us that we were in the wrong place when we didn't recognize anyone in attendance, including the bride and the groom once they appeared. Sometimes an epic fail makes for a great story!

Mike and Sarah at the wrong wedding... Thanks to the groomsman who took this photo!

So by the time we stayed another night in Des Moines to attend the correct wedding, we really didn't get much time to build over this long weekend. That's ok though! We did get some time to continue with the baggage door and take some more pictures of the custom latch assembly though:

Cutout is 1" x 3-3/8", starting 1/2" forward of the aft edge of the door and vertically centered on the existing hole punched for the key lock. The cutout will go through two rivet holes in the door leaving two small notches in the cutout, but they will be covered by the latch when it's installed.

A 1/8" thick steel plate 3" x 5" was fabricated to strengthen this area of the door. The cutout at the bottom is made to clear the baggage door frame.

The latch installed into the hole and screwed into place

The baggage door with latch installed

The inside baggage door cover with modified  cutout, measuring 3-1/4" x 1-1/2". A new #30 hole was drilled to mate with the frame, which must be cut to allow clearance for the latch.

The door riveted together and installed in the plane

The latch holding on to the F-1031 Upper Baggage Door Seal (the bolt is temporarily wrapped in electrical tape until I get a rubber stopper for it)

Closeup of the latch and frame cutout

The open baggage door, inside cover isn't riveted on yet

A video of the door in operation

It works great!! I still need to figure out two more things with the door before it's done: (1) The frame needs stiffening in the area where I cut it so that it won't have a tendency to bow. It's not bad as-is but I want it to be a little better. I should be able to rivet a piece of 0.032" aluminum between the two halves and that should easily take care of it though. (2) Before riveting on the inside cover, I want to source and install a small strut to facilitate the opening and closing of the door, as well as limit its travel. In addition, I'll need to finish up the F-1031 channel and install provisions for a microswitch and striker plate. Again, shouldn't be too big of a deal.

That's pretty much it for now! I'll be on travel the rest of this week, so there probably won't be much more progress until this coming weekend... until next time!

Baggage Door

As stated in an earlier post, I held off on completing the baggage door section while I searched for a latch mechanism that I could install and have a little bit more advanced open/close function than the standard lock-arm provides. Well, good news! I have found and settled on a latch: The Southco model C2-33-21.

Southco C2-33-21

This latch works by pushing in where the key lock is, and then the rest of the lever "pops" out. There's actually a video I found of its operation here on youtube: https://www.youtube.com/watch?v=h2d2S5Rcqgg. One downside is that the key for this will be different than the one for the door locks and ignition, but I think that should be ok. To close, the arm has an adjustable bolt that will catch on the back side of the F-1031 Upper Baggage Door Seal and hold the door shut tight. I'll probably have to install some kind of striker plate for that (maybe even with a microswitch) so that it's not just holding on to the aluminum. Shouldn't be too hard.

Well, I got the latch in the mail yesterday and so it's time to get to work on it. Unfortunately I don't have any pictures of the process yet (I will soon, I promise) but it's going really well so far! I was able to hang the door and get everything aligned and the hinges drilled. I'm really happy with the alignment of the door. It was a process that took a little longer than I imagined it would, and it was really quite tedious to get it to sit just perfectly centered and square in the opening, but Sarah and I prevailed. I feel like part of our success was due only to luck, but I'm not going to complain about that. Once the door was hung, I then made the rectangular cutout for the latch in the door skin and also cut a steel reinforcement plate to go behind the outer skin and provide extra support. The latch fits in place and catches on the F-1031 perfectly! I really like the geometry of it, and once I get everything finalized I'll take a bunch of pics and provide measurements, etc.

In the procurement department, big things are happening too! We ordered our stick grips from Tosten; our fuel filters, check valves and Walbro pump are on the way; ordered some 2 AWG welding cable, ring terminals, and hydraulic crimping tool from Temco; got some Amphenol 31-326-RFX BNC connectors and Harbour RG400 cable; and finally bought the necessary 5052-O tubing and a number of AN fittings from Aircraft Spruce to be able to start fabricating the fuel and brake lines. I've been talking with the folks at DJM about a console throttle quadrant for the RV-10, and I've also been talking with Paul Grimstad about the Control Approach rudder pedal system. He's working on a new design and it's taking a bit longer than I think he originally anticipated, but the good news is he is "back in business" making pedals so however long it takes it will be worth the wait! He's been great about getting back to my many pestering emails and providing updates, photos, etc. I'm confident this will NOT be a P-200 mag situation ;-)

I've also been pondering what to delete/add to my finish kit order. I've looked through a number of build blogs about this and have settled on doing pretty much the same thing Ed Kranz/Justin Twilbeck did for their finish kits as far as deleting wheels/tires/axles to upgrade to the Matco/Desser products, and a few other tidbits. Justin's delete list can be found here. I'm also going to be deleting the windows because I'll be using the Cee Bailey ones. I really hope that upgrade is worth it, I haven't bought them yet but since I've already deleted the fuse windows I'm kinda stuck with that decision now. I'm sure it will be fine.

Well, that's pretty much it for now. Hopefully for my next installment I'll get some photos up of the baggage door!

Brake/Fuel System Design - Initial Plan

<<<I apologize in advance, this is going to be a long thread filled with lots of theories, ramblings and thoughts.>>>

So tonight instead of doing any actual "work" on the plane, I did some major research and planning on the brake and fuel systems. The brake system is fairly straightforward--at least the part in Section 36--which essentially runs two lines from the firewall area to the landing gear mount area. If you want to include the Matco parking brake, then it's a simple insertion into the lines "somewhere." Most folks install their parking brake valve on the firewall, but after reading a pretty descriptive (and hilarious) description from builder Myron Nelson about how difficult it is to reach the valve should it ever need servicing, I will be locating mine at the rear of the tunnel, where the brake lines diverge to go to the R and L sides. While unconventional, this location should be a lot easier to access in the future, and make for an easy control cable run in the tunnel. Pics and diagrams to follow.

Next, on to the fuel system. By far, this is the more complex, expensive, and thought-provoking system between the two. It is also a system that has been over-engineered and/or over-complicated by more than one builder, and sadly it is has also been at least a contributing cause for a number of fatalities in the experimental aircraft world, including the infamous accident that killed John Denver. There has even been one or two accidents involving RV-10's and poor fuel system design, although both of the ones I am aware of also involved highly modified automotive engine installations, which of course kind of throws all the usual stuff out the window to begin with. That's not what we're going for here.

What we ARE going for here though is what I'm going to call a "minor variation" on a tried-and-true system design, for two very specific reasons: (1) I am installing a fuel return line for future compatibility reasons, should I decide to install an electronic fuel injection system (e.g. EFII); (2) I will have provisions to connect a removable auxiliary fuel tank in the backseat or cargo area when extra endurance is required. Nothing too crazy, but any kind of modification needs to be considered very (and I mean VERY) carefully. So, we need to start with a standard RV-10 fuel system, analyze the crap out of it, and then (did I say carefully?) make our tweaks. So... keeping all this in mind, let's get started. Here is a diagram I made of a relatively standard, tried-and-true fuel system design to start with as a reference point.

"Standard" RV-10 fuel system design, IO-540 w/ Mechanical Injection

So I'm starting with this diagram above and calling it "Standard", but really there are already a few modifications depicted here. Notably, the check valves on each of the R/L vent systems, and individual pre-filters instead of the single filter at the boost pump module. The vent check valves are installed in each wing root and serve as a secondary vent, should the primary vent become clogged with ice (or a very unlucky bee). The individual prefilters simply separate the R/L fuel tanks a bit more, so that in the event one tank coughs up some really nasty gunk in the fuel and clogs the filter, you can still switch to the other tank and have unobstructed flow. These are two very common modifications that are pretty well documented already on other builders' sites, and I feel that they are both accepted pretty openly as safety improvements for protection against icing and fuel contamination.

So now, let's analyze the system a bit and look at the individual components, particularly the boost pump module. In the diagram above, the boost pump module is shown as three individual parts above the fuel selector: The check valve, the boost pump, and the regulator (or pressure relief valve). The way it works is best understood if we split into two distinct modes of operation: boost pump off and boost pump on.

• Boost pump off: Suction from the engine's mechanical fuel pump pulls fuel through the check valve and forward through the system. Fuel can technically also flow through the pump and its internal check valve (if present) but we will consider that a path of more resistance. Fuel does not flow through the regulator.
• Boost pump on: The pump pressurizes fuel going toward the engine, "forcing" fuel through the engine's mechanical pump and increasing system pressure, particularly at the inlet side of the mechanical pump, which is where vapor lock can occasionally occur. Due to this change in pressure, the check valve closes and prevents fuel from flowing backwards. Lastly, because the boost pump is capable of producing higher than desired pressure, the regulator opens for any excess of ~30psi and allows some fuel to return to the pump inlet.

Looking at the different boost pump modules available out there, I came across three different brands: The Van's-endorsed Airflow system, the Andair system, and the EFII system.

The ironically-named Airflow fuel pump module seems to have a number of happy customers, and it is Van's choice (always a plus), but it uses an Airtex fuel pump which is a brand I have quite a bit of personal experience with in the automotive world and regard them as inferior to just about any other kind out there. Furthermore, you can go buy the Airtex E2351 fuel pump used in that module for around $60, so I'm a little hard-pressed to cough up $500 to buy it.

The Andair pump looked awesome at first glance. Less external lines and fittings to go wrong, an internal regulator, and oh wow a BRUSHLESS motor! I've always wondered why brushless fuel pump motors haven't really caught on, it seems like they would be vastly superior to the traditional brushed motors in terms of both noise and longevity. Well, it turns out after reading a number of articles online about this particular pump that it is actually *louder* than others and there have been a number of failures, particularly early on due to some early design flaws. A rather disgruntled early-adopter made a video highlighting all the design flaws of this pump and posted it to Youtube, visible here. To be fair, it appears that the company has made improvements to the design since this time, and I am not aware of any recent failures of this pump. Even so, that was enough to make me move on, especially since this is the most expensive of the three options... the FPK-540 is priced at $850!

Finally we have the EFII module. This thing seems great-- it uses a Walbro brand pump (MUCH better than the Airtex in my opinion) and it has a custom check valve/regulator that boasts the lowest "cracking pressure" of the three available models. This means that the mechanical pump doesn't have to "pull" as hard to get fuel when the boost pump is off, which is a good thing especially at high altitudes or hot temperatures. And, it's very competitively priced at $649.

Between the three choices, to me the clear winner is the EFII module. There's just one thing left to consider though: the fuel return line that I have available on my system. If we take a second look at how these boost pump modules work, we can introduce an additional benefit that a true return line can provide. The way these modules are designed (in the absence of a return line) is that the regulator's return path is cut very short, sending fuel back only a few inches and re-introducing it at the inlet of the boost pump. With low demand from the engine (e.g. on descent), the majority of fuel follows this small circular path, absorbing heat from both the pumping process and the warm environment of the tunnel. Since we want our fuel to be as cool as possible for a number of reasons, this is not an ideal situation.

So, what if we pieced our system together instead of buying a pre-made module, using exactly the same kinds of parts as above, but allowed for the regulator to send fuel all the way back to the tanks? I spent hours online tonight, searching for pumps, check valves, and regulators, and I believe I have found a winning combination:

• Walbro GSL393 fuel pump ($98.18). This is (I believe) the exact same model of pump used in the EFII boost pump setup. It has exactly the right spread of pressures and flows to exceed the demands of a 260HP IO-540 engine without going way overboard. The larger GSL392 pump is somewhat more popular in the automotive world but it has significantly higher output, which really is unnecessary here. The GSL393's performance chart can be seen here:

Walbro GSL393 Pump Performance

• McMaster-Carr 47715K21 check valve ($30.07). This valve has 0.5psi cracking pressure (VERY low) and PTFE seals that work well with all kinds of fuels and in a wide range of temperatures. I had originally considered some other valves with Buna-N (nitrile) or Viton seals, but nitrile doesn't hold up to certain kinds of fuel additives, and Viton doesn't perform well in cold temperatures (below around +10 deg F). I actually spent considerably more time than I thought I would looking at check valves, there are a lot of different options out there and care must be taken to choose the right one.
  (EDIT 9/2/15: After further research, I've selected the Parker 2625 "Swing-type" check valve, price TBD. This valve is aluminum instead of brass, and has a fluorocarbon seal with even greater temperature range, and is designed specifically for fuel systems like this)
• Aeromotive 13301 Fuel Pressure Regulator ($131.94). This regulator is adjustable between 3-65psi (30psi desired here), and will work perfectly to send excess fuel back to the tanks. It is also rebuildable and seems to have a strong history of reliability.
  (EDIT 9/2/15: A simpler method may be to use a standard relief valve with 25 or 30psi rated pressure. I'm torn between the two options and will keep searching on this.)

Cool! The same and/or equivalent parts for less than $300... I like it. So that's it, you say? Well, almost. There is one more thing to consider. Now that we have a standalone regulator, what if we move it to the head of the line and "tee" it off the entry to the fuel injection servo? This way, we eliminate any potential over-pressurization issues along the whole fuel system, and we now have the ability to run cooler fuel all the way to the servo. This should pretty much eliminate any hot-start issues and/or occurrences of vapor lock. This isn't a wild or crazy idea of mine, either... it's been the standard for how automotive fuel injection systems have worked for at least the past 30 years (which is of course about 40 years *after* these Lycosaurs were designed). So, after all that, I present you with my first draft of the fuel system diagram:

N165MJ Fuel System Design - First Draft

(EDIT: To see post with Second Draft, click here)

If you've been following along from the previous diagram, you'll see that really not much has changed except for the "duplex" fuel selector, the location of the pressure regulator, and the path of the returned fuel. I'm going to stew on this design for a little while and figure out the number of connectors, tees, fittings, etc etc that will be necessary to make this all work, and go from there. In the meantime, please feel free to comment (or email me) your ideas or opinions on this design! I welcome all feedback.

One other thing left to cover is the aux tank connections, but that is fairly simple in design. My plan there is to have two fittings and an electrical connector hidden somewhere in the R interior side wall that I will connect to a custom ~20gal fuel cell that can be placed in the rear seat floor or baggage compartment. Fuel will be burned from both main tanks as normal, and then when a tank has enough room in it to accomodate the fuel from the cell, an electric transfer pump inside the cell will be activated to refill the selected tank (either right or left) through the return line. It should work pretty slick... or at least that's the hope.

Whew! Sorry for such a long post tonight. Hopefully I've been able to document my current thoughts in a clear way. Excited to see how this all plays out!

Section 35 Complete!

Knocked off another section this weekend! By far the hardest part about this section was installing the rear floor pans, discussed in a previous post. The rest of it is really for the most part final-drilling a bunch of #19 holes, dimpling a bunch of #8 screw holes, and maybe the occasional nutplate installation. Easy peasy. Of course, this section isn't really ever "complete" until every last panel has been upholstered/painted and then screwed into position, but that's not necessarily going to happen until the plane is ready to fly-- certainly not until a number of other systems have been installed like the flight controls, brake lines, fuel lines, and wiring. So, I'm calling this section "complete" but really there's just a pile of bare aluminum panels that still need to be painted or upholstered. That will come in time!

Some of the access panels in place (shown unprimed)

It's hard to get the whole bird in the photo nowadays... not a bad problem!

Oh! I almost forgot. Spent a good amount of time this morning modifying the oil cooler mount that I had added to the fuselage kit. Because my engine has the piston cooling oil nozzles, oil cooling needs to perform better than similar engines without this feature (with the positive tradeoff of lower and more stable engine temperatures overall, of course... at least that's the theory). Due to this, I will be using a one-upsize oil cooler, the Airflow performance 2008X. This cooler is the same width and thickness as the stock one, but is about 1-5/8" longer. The mount, then, will need to be modified to accept this larger unit.

The stock VA-186 Oil Cooler Mount

Spacer brackets fabricated to extend the cooler's length

Modified VA-186 mount to accept Airflow 2008X Oil Cooler

EDIT 11/1/2015: I think I may have messed up. Now that the finish kit is here, I think the engine mount will actually be in the way of the larger oil cooler. I may have to redesign this thing from scratch, we'll see. Keep looking for updates on this.

In theory, it's not a very difficult modification. However, it ended up taking about 4 hours to get it just right. Basically, I separated the top plate of the mount from the rest of the assembly and fabricated a few spacer extensions to lengthen the open area for the cooler.. By changing the angles that the cooler originally sat at by a small degree, it retains the same footprint on the firewall and now accepts the larger oil cooler. Cool!

Speaking of cool, we've arrived at kind of a "cool" pivotal spot in the build. Most of the metalwork is done, at least as far as the primary structure of the airframe is concerned. Of course we have by no means set our last rivet, but everything from here on out is really pretty minor as far as aluminum work goes. From here onward, the majority of tasks are going to be centered around plumbing, wiring, control systems, and of course FIBERGLASS. As with many builders before us who have gotten to this stage, we've sorta procrastinated on some of the smaller glass tasks that have presented themselves along the way, and now have a stack of small bits to make as well as a couple large ones. I've heard from many builders that the canopy top and doors are some of the most time-consuming and painstaking parts of the build, and make up for a substantial portion of the total build time.

Also, it's time to start buying "stuff." Everything from wiring, stick grips, fuel lines, brake lines, the rudder pedal system, custom tidbits/upgrades, antennas, lighting, upholstery, and even the beginnings of some avionics. This is both exciting and depressing, as it is going to require careful management of monthly expenses and planning out the logistics of what needs to be bought and when. The UPS guy, if he doesn't already, is going to start to remember this house over the next few months! Who am I kidding, he's gotta already know us :-)

Over the next few days, I'll be assembling a list of things left to do before the finish kit arrives (don't worry, there is still PLENTY to do, I just need to make a list and organize/prioritize). Among the next things to do: (1) measure custom lengths for brake/fuel lines and decide if we're using flex or solid lines, probably a combo of both; (2) paint the interior; (3) continue with the baggage door after my latch arrives; and (4) begin fiberglass work.

Until the list is complete though, marathon-nights of extreme building may be replaced by marathon-nights of extreme reflection on what to do next and how to do it. The metamorphosis from builder to philosopher begins....

Section 35 Begin

Started Section 35 - Access Covers and Floor Panels today. The first thing they have you do is prep and rivet the rear floor pans into place. I got all the holes drilled, deburred, dimpled, scuffed, and primed in fairly short order. Riveted a few nutplates to the bottom side and thought things are going quite nicely so far, all that's left now is to drop them into place and rivet them down! I must say, this part of the plans caught me by surprise how difficult it was. In my mind, I thought "it's a bunch of blind rivets, should take 10 minutes" but in reality there are a number of solid rivets all around the perimeter, you have to match-drill into the center section spar, and worst of all the panel itself is *extremely* difficult to wedge into position.

The floor panel has three cutouts along the forward side that are supposed to go around the seat brackets and the middle reinforcing hat channel attached to the spar. Well, on mine (and others I've read about) the cutouts were just a tad too narrow to fit around the seat brackets, and this makes installing the floor impossible. It's not evident right away that this is the problem unless you're specifically looking for that, and that's what makes it tricky. Instead, you'll just want to push harder and harder until SNAP something gives. Usually it's the flange on the side of the panel that will buckle. If you're lucky (like I was) it didn't crack, it just bent a bit and I could straighten it back out.

Well, after salvaging my screwup on the L floor panel and getting it all riveted into place, I thought I'd be a hero and take a million photos of the method I thought I had "perfected" now for the R floor panel to show others "the way"... here's what I came up with:

Fiberfrax insulation laid out, and two scrap sheets of thin aluminum to help the panel slide past the seat belt brackets and rivet heads

Panel laid into place with the aluminum sheets on the side helping it slide down

Check for appropriate clearance around the seat brackets

Take an automotive panel/upholstery pry tool to help wedge the panel from the backside

Now just pry it forward to clear the rear spar center section, give her a little push, and....

OWWWWEEE.

Oh for crying out loud! It was going so perfectly too. Just a bit too much pressure in the wrong spot and the damn thing buckled again... this time causing my hand to slip and go right into the sharp, unfinished corner of the aluminum sheet I had so proudly put in place to guide the panel down. So much for a flawless install procedure.

The buckle in the floor panel. Again like the L side, it didn't tear or crack thankfully and could be straightened out by careful and judicious use of the flush rivet set on the 3x gun.

So, in all reality it wasn't the worst situation in the world to be in. Got my hand all patched up (yes that's electrical tape holding the band-aid in place), stuck in a bunch of clecos and straightened out the buckle. In a few hours' time I had both panels fully riveted into place, and a very sore back from sitting in a number of incredibly awkward positions:

L floor pan after riveting

R floor pan after riveting - buckle is erased thankfully!

Whew! Glad that bit is over. Note to future builders: good luck! These floor panels stink. But, when they're done, you have a nearly complete floor in your entire airplane.. yay!

Tomorrow if there's time we'll probably rivet down the rest of the back seat panels (they were left up to provide access to riveting the aft edge of these floor pans) and continue with Section 35!

Section 33 Complete!

Well... sort of complete, anyway. Today I worked on the second half of Section 33, which dealt with installing a cover panel on the R side of the baggage compartment (opposite from the door) and drilling/deburring/dimpling holes for the baggage bulkhead corrugation panel. I say "sort of" complete because there are a couple parts that I will be leaving uninstalled for now, namely the R side cover panel because I want to make another conduit run behind it to put wires that I want to keep separate from the other two "main" looms. I had ordered some 3/4" conduit from cableorganizer but for whatever reason it's been delayed an extra couple weeks.

Guess it's a good time to vent about cableorganizer.com. It's been a bit frustrating dealing with them, so far they are my least favorite vendor I've dealt with on this build. They charged/re-charged/refunded my credit card a number of times for some reason which triggered a fraud alert that I had to deal with. When I originally placed my order, everything was said to be in stock, but suddenly one item (zip ties) mysteriously changed to a ship date of 8/31. No big deal. The 3/4" conduit in question though was marked as shipped with the rest of the order on 8/19 (which by the way was 6 days/4 business after the order was placed), however it wasn't in any of the boxes that arrived. When I called to inquire, I was told it wouldn't ship until 8/31, along with the zip ties. This was *not* what was clearly printed on the invoice and all order tracking notifications I received. Grr. Maybe I'm just used to places like amazon and aircraft spruce that ship within a day or so, and seem to be much more "on top of it". Or maybe I'm just bitter about spending over $250 on plastic tubing and zip ties... :-/

Anyway...... first-world problems I guess. The rest of Section 33 went pretty well, and I now have a number of nutplates installed around the perimeter of the F-1006 bulkhead and down the F-1028 channel.

Drilling the #19 holes around the F-1006 bulkhead

Panels removed and nutplates installed!

In the pic above, you may notice that the F-1031 Upper baggage door seal channel is not yet installed. I'm also leaving this part out for now until I figure out exactly what I'm doing for the baggage door latch. I'm not crazy about the idea of the standard key-only latch mechanism; I'd rather have the ability to lock-unlock it and then have some kind of paddle handle or slide latch to open and close the door. I'm searching far and wide for the "perfect" latch and it's been kind of hard to find so far. I'll keep searching, and I don't think that will really keep anything else from continuing in the meantime.

I also finally installed nutplates along the forward tunnel along the top edge. Technically this was supposed to be done a while ago (I think in the firewall section?!) but I kept procrastinating, knowing that it could be done at basically any time since there is easy access to that area. No worries, that's done now too.

So, all that's really left to do with Section 33 is final-installing the F-1080 baggage cover once I finally get my conduit, and final-installing the F-1031 baggage door channel once I figure out what my baggage door latch is going to be. Oh, and installing the rear seat belt wear blocks, but again I want to hold off on that until I actually have my restraint system purchased and in-hand. Three quick and simple tasks... good enough for me to call 33 done!

Next up, I'm going to skip 34 (baggage door) for the same reason as above until I find the right latch, and going to start on 35, Access Covers and Floor Panels. Should be a fun section, hopefully!

Baggage/Rear Seat Floors

Productive day today! Primed all of the parts needed to complete the first half of section 33 over lunch and then got to work laying insulation and riveting the floors into place! Similar to the forward floors, I used a layer of 1/8" Fiberfrax insulation, and topped it with Ultratouch under the rear seats only. Under the baggage area, I used aluminum tape to secure the relatively thin and light Fiberfrax.

Insulation laid up, ready to install floors!

I started riveting the floors on and realized my pneumatic rivet gun wasn't working right. It started taking two, and then three squeezes to actually set the rivet, which got old quick. I thought maybe the gun was starting to wear out or something, but it turned out to be part of the internal mechanism had started to unscrew from itself and was limiting its range of motion. We had disassembled the gun months ago to clean all the proseal out of it, and I think we must not have tightened everything back up fully. Whew! That was an easy fix, I was hoping I wasn't going to have to end up buying another gun or something. Anyway, after a night of riveting here's what we ended up with:

L baggage floor and baggage door opening, from inside

Baggage door opening, looking inside toward floors

All sealed up!

Baggage floors

We're now through Section 33-7 Step 5... yay! The second half of this section will now build on this and install a cover panel on the R side of the baggage area, and match-drill and install nutplates to hold the Baggage Bulkhead Corrugation panels.

The end of Section 33 is in sight!!!