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Archive for November, 2011

Preparing to Rivet Outboard Bottom Skin – 1 hr

November 30, 2011 Leave a comment

Wednesday Nov 30, 2011

Tonight I only had a little time available so I primed the surface of the inboard skin that lies under the outboard skin. I taped off the area to be primed then roughed up the surface with scotchbrite. Next I cleaned the surface well with MEK.

I brushed a coat of Ekoprime on the surface. Brushing is not as uniform as spraying but for this small area I’m not willing to set up the spray gun, especially since this surface will be covered by the outboard skin.

As that started to dry I modified two AN fittings for the fuel vent lines. To remove the threads I put the fitting in my drill press and just filed the threads off using a file as the part spun in the chuck. Then I cut off the end at about a 45 degree angle and sanded it smooth on the belt sander. Here is a photo comparing a modified fitting with an unmodified one. Now apparently I need to get some screen material to bond to the end to keep bugs out.

Categories: Skins, Wings

Finished Left Inboard Bottom Skin – 1.5 hrs

November 29, 2011 Leave a comment

Tuesday Nov 29, 2011

Scott came by after work this evening and helped me bang out the remaining rivets on the left inboard bottom skin. Yes, the jigged-up bucking bar I made last night helped a bit. Still not what I would call easy, but better than before. Here is a “candid” shot of Scott inspecting rivets.

And here is just a victory shot of the “finished” inboard skin. The last two rows will be riveted in overlap with the outboard skin. Oh, and I also have to rivet the skin to the flap brace with the flap hinge but that will be a piece of cake compared to the interior rivets.

Categories: Skins, Wings

Making Tool Adjustments – 1 hr

November 28, 2011 Leave a comment

Monday Nov 28, 2011

I did not have a rivet partner tonight and I didn’t really have much time anyway so I spent it thinking about how I might make this riveting process a little easier. I decided to modify my tool slightly to help me align the bucking bar in those blind situations along the aft spar. Here is what I came up with.

Basically the wood pieces act as a handle and a guide. I used the longer piece while riveting yesterday but I needed something to help me get the head of the bar flush with the rivet. Reaching in blind it is easy to get the bar tilted and drive the rivet unevenly. The triangular block gives me a guide along the aft spar to push the bar against to make the head flush in at least one axis. It’s still blind but if I can reach the rivet head using the handle as an extension and push the block up against the spar flush I have a better chance of getting it aligned right. I hope I can try it tomorrow night.

Categories: Skins, Wings

More Progress on Wing Bottom Skin Riveting – 5 hrs

November 27, 2011 Leave a comment

Sunday Nov 27, 2011

My best rivet partner (Denise) is out of commission for a while because she broke her wrist and bruised some ribs in a bicycle accident so my friend Scott came over today and helped me make more progress riveting the bottom inboard skin on the left wing. Many of these rivets are very tough to reach. We spent about 3.5 hours and only made it half way through the fifth rib. If you click on the picture to blow it up you can probably count the rivets we installed. That weird shadow on the wing is from my Wagner house painter which is hanging from the ceiling above the wing (I bounced the flash off the ceiling). I keep thinking there must be an easier way to do this riveting but I can’t come up with one. I don’t see how anyone could do this solo. Is there a secret riveting order I could follow to get better access? Vans instructions are too vague on this.

Other than that I started making the fuel line that goes between the fuel valve and the pump this morning. The first bend I made with my tubing bender through about 150 degrees. The picture below shows the first bend. Those other fittings are for the fuel tank vents which I plan to work on next. It became clear that I will not be able to use the Imperial bender for all the plumbing bends so I ordered a set of those coil spring benders that you slide over the tube to prevent it from collapsing. Avery Tools had a Black Friday weekend deal with 15% off and $1 shipping so I took advantage of that to order a stainless steel hot air box for the firewall and get some more Snap Socs (used to reduce the risk of smiles on universal head rivets).

Categories: Skins, Wings

Started Riveting Bottom Skins, Left Wing – 5 hrs

November 26, 2011 Leave a comment

Saturday Nov 26, 2011

Before hitting the sack last night I was thinking about how I had routed the pitot heater wires yesterday and it occurred to me that I forgot to twist the power wires. A friend who is an electrical engineer told me that twisting the wires was one of the most effective ways of minimizing the electromagnetic coupling between wires. If there is any RF noise on these wires twisting them will minimize the radiation to/from other wires such as antennae and strobe lights. So first thing this morning I pulled the red/black wires back out and twisted them together as a pair, then ran them back through the wing. You can see the result in this picture. There’s no way I’ll ever know how much this helps but if I didn’t do it and I have electromagnetic noise issues later I would kick myself.

After that I torqued a few more bolts in the bellcrank area and applied torque seal. I mixed up a small batch of ProSeal and applied a small amount to the electrical conduit at each of the wing ribs. This is to keep the ribs from cutting through the conduit over time due to vibration. Then I spent about two hours cleaning off the work bench and the area around it before moving the left wing onto the bench to install the bottom skins. The shop really needed some cleaning and it is much more pleasant to work in now. Here is the wing moved into position for skin riveting.

I did the first few rivets solo along the rear spar in the first three bays. I taped the tungsten bucking bar to a piece of wood to give me a better reach into the wing.

After that I got some help from one of my daughters to complete the first three ribs in the wing walk area. This is one of the toughest parts of the project so far. I hate bucking rivets when I can’t get eyes directly on the shop head and most of these rivets are blind and the hand positions are awkward at best. But like Bruce Swayze said on his web site, you just focus on one rivet at a time and keep plugging away. This fourth row looks like it will be a challenge as well as the remaining rivets on the aft spar.

With the first three ribs completed I shifted from bucking from the inboard end to the outboard side. I used a piece of rope attached to the garage door track to lift up the outboard edge of the skin. I seems to work better with one person focused on bucking and one shooting the gun without having to worry about holding the skin up. I’m being cautious here because I don’t want a kink in this skin.

Categories: Skins, Wings

Wired Up Pitot Heater, Preping Left Wing for Closing – 4.5 hrs

November 25, 2011 Leave a comment

Friday Nov 25, 2011

A long time ago I “finished” the wings without riveting the bottom skins because I was uncertain which EFIS I was going to install and which autopilot servos I would use, one of which installs in the wing. Well the time has come to mate the wings to the fuselage and the bottom skins need to be on for that so I need to wrap up the wing wiring and close’em up.

So today I finalized my planning for wiring in the wings and ordered wire and connectors from SteinAir for the Dynon autopilot servo. That will take a few days to arrive but in the mean time I could work on the left wing and the pitot heater wiring which I also left incomplete last winter. Here is what I came up with for routing. I installed a 3-pin Molex connector for the heater module and ran those wires down the wing to the root. I also looped the heater wires around and tagged them down to a rib using tie bases. It is pretty clean and there is plenty of clearance to the bellcrank.

Here is a view from the top so you can see the wiring routing better.

This next photo is the pitot tube and the plumbing routing.

I also decided to dimple all the holes in the bulkheads for the upper aft skins which I probably should have done weeks ago. So I took the upper skins off again.

And while I had such good access I finished installing the clips for the static line routing. These are now riveted in place. I left about 6 extra inches of static line tube to make sure I don’t come up short later.

And for fun I decided to cleco on the ribs that support the instrument panel. This is just checking things out. They will come back off again tonight.

Miscellaneous Chores – 2 hrs

November 24, 2011 Leave a comment

Thursday Nov 24, 2011

Happy Thanksgiving! This morning I was able to get out into the garage early for a couple of hours before the activity started to get ready for our Thanksgiving get-together. I was hoping I could quickly install safety wire on the roll servo motor bolts but it took me five tries to get it good enough to be satisfied with. This one was tricky. It’s still not perfect but I am satisfied it will do the job.

Then I made a little clip to support the Tee in the static line on the F-708 bulkhead.┬áThis will keep the T from working it’s way loose from the static line under vibration. I made it from .020 thick Alclad sheet and secured it to the bulkhead with one LP4-3 rivet. The screw and the lock nut came with the Tee in the SafeAir1 kit.

Then I made several more clips to hold the static line to the back of the F-706 bulkhead in route to the ADAHRS unit. Here you can see two of the clips installed with clecos. I will rivet the clips later with flush head rivets on the forward side of the bulkhead. I stopped here because I am uncertain about the routing from here. I will either route it down the center rib with the pitot and AOA lines or I will route it along the nearest J-stringer.

Finally I installed a piece of plastic conduit in the aft fuselage through which I plan to route the electrical wiring to the tail; namely the strobe on the rudder. This view is from the F-706 to the F-707 bulkhead.

This is from the F-708 to F-710 bulkhead.

Fuel Pump Cover, Static Lines, Roll AP Servo – 5 hrs

November 23, 2011 Leave a comment

Wednesday Nov 23, 2011

With my recent success designing and fabricating an ADAHRS mount from scratch I felt confident enough to start fabricating the fuel pump cover today. I designed this over the last few days and I bought the raw materials last weekend at Aircraft Spruce. The first part was the center cover which is cut and folded from 0.020 thick Alclad sheet. Here is a picture of my custom cover next to the Vans stock fuel pump cover. You’ll see how this works in a minute.

In this photo you can see the side covers laid out on the .020 sheet material ready for cutting.

Here the side covers are assembled to the center cover with clecos. It doesn’t look too bad so far.

This is how it will mate to the fuel valve cover. I need to make a new fuel valve mounting plate with an upper extension for the trim cable mount that is rectangular and angled at 60 degrees to sit flush against those three flanges but I don’t have the .062 stock right now. My aircraft is a bit unusual in that I am combining fuel injection and manual elevator trim. I seems that most people go with the electric elevator trim but I really like the manual trim knob for the feel and resolution it provides. What I like about this fuel pump cover design is it will fully enclose the elevator trim cable.

I placed it in the cabin just to get an idea if it was going to fit the way I hope it will. It needs some angle pieces to attach it to the F-782 cover but it looks promising. I wish I had that .062 stock.

I shifted gears over to the static ports again because the ProSeal was pretty well set after three days. I removed the tape and here is how the ports look on the inside.

Routing the tubing was pretty simple. I used one T to split a single line into two, one going to each port. I also made four little clips out of .020 alcald stock to hold the static line to the main longeron. You can see one in this picture.

I ran the line up to the F-706 bulkhead where it will turn upward to go to the future ADAHRS on my new custom mounting bracket. Here you can see the little clips that guide the tubing and keep it from flopping around.

The next topic is the installation of the Dynon roll servo actuator for the autopilot in the right wing. I need to get this done soon because it is just about time to mate the wings to the fuselage and drill the aft spar attachment. The first step was to remove the bellcrank and drill a hole for the servo linkage. It’s the middle 3/16 diameter hole in this view.

Then I replaced the stock bellcrank bracket with the Dynon-specific bracket which also supports the servo motor. That includes two cadmium plated parts you see in this view.

Then I installed the motor and secured it with three AN3 bolts and washers. I torqued the bellcrank support bracket bolts and marked them with torque seal. I still need to safety wire the three bolts that hold the motor.

My last task today was to assemble the servo linkage with two rod end bearings and set the distance between the two rod end centers to 5.00 inches. I torqued the nuts but I will probably also stake these with epoxy.

Designed and Fabricated ADAHRS Mount – 4 hrs

November 20, 2011 Leave a comment

Sunday Nov 20, 2011

While the ProSeal is curing on the static ports I started working on the ADAHRS mount. It will be much easier to take care of this now while the aft top skins are off because it is tough to crawl in there to do the work from the inside. I am planning to mount one Dynon ADAHRS but I want to allow room for a second backup unit later. After looking at some of the mounts other builders created I decided to design my own. I will mount it to the upper rib and the left J-stringer in the upper aft fuselage. I started by making a bunch of measurements of the rib and J-stringer and sketching out my ideas on paper. When I had an approach I liked I made a cardboard mockup to see if it looked good in three dimensions. Here is the mockup on the bench.

Here it is clamped in place in the fuselage without the upper skins in place. The only thing straight in the fuselage here is the center rib which runs forward and aft basically on the centerline. It angles up toward the front however and the stringer angles up as well as tapers outward as it goes forward. The stringer is also tilted a little to the left. So one side of the mount has to able to accommodate the compound angles to match.

Satisfied that it will fit I started making it in aluminum using some raw materials I picked up at Aircraft Spruce on Saturday. The bottom plate is .020 thick Alclad sheet and the bottom ribs are .063 x 3/4 x 3/4 angle. In this photo I have cut the bottom skin and angles and match drilled them for rivets. You can see my full scale layout of the ADAHRS next to it for size. It fits fine but there is not a lot of extra space. Basically it is customized to the Dynon unit dimensions.

The sides of the mount are also .020 Alclad sheet and I added some fold-over braces to increase the side to side stiffness. Here are the parts initially cut out of raw stock.

Then I folded the side members and installed them on the bottom structure and riveted it all together. I will prime and paint this one as a complete assembly. The front of the ADAHRS has three pneumatic ports; static, pitot, and AOA so I left this side of the mount wide open for access.

Here is the aft side so you can see the side braces folded over and riveted to the aft angle. The ADAHRS has a network cable connector in this side that is right on centerline. The braces leave plenty of room for that connector and cable.

The ADAHRS needs to be aligned within one degree of parallel to all three aircraft axes. I probably can’t get the mount installed precisely enough to those tolerances at this stage but I can get close. So I used my level to temporarily clamp it level in longitudinal and lateral axes and I measured from the F-706 bulkhead to get the front angle parallel for the yaw axis alignment. I will shim the ADAHRS at installation to do the fine tuning. With it very close to dead on I drilled three holes through the J-stringer on the left side member as seen in this photo.

I was uncertain if the upper skin would affect the overall alignment of the mount so I cleco’d the skin on from the left longeron to the right J-stringer. That way I could lift up the right side of the skin and reach in to tweak the alignment of the mount before drilling the holes for the right side attachment. Again I adjusted the mount slightly to level it in pitch and roll and measured from the F-705 bulkhead for the yaw alignment.

Then I drilled six holes through the center rib to secure the right vertical side of the mount to the rib.

Here is a different view using a longer exposure to capture the image with only natural lighting. I am happy with this design so far. I am still deciding how I want to secure it to the rib and stringer and what order to assemble it. I will either rivet it in before installing the top skin or I will use pop rivets later to rivet it in. I will use brass screws and nuts to mount the first ADAHRS unit and if/when I upgrade in the future to a dual ADAHRS I just plan to stack them.

The design is clean and light weight. It is also stiff so it should not be vibrating around too much. I’ll look into posting the plans for the parts on the site for others who might be interested.

Categories: Aft Fuselage, Fuselage

Torqued Gear Bolts, Installed Static Ports – 2 hrs

November 19, 2011 Leave a comment

Saturday Nov 19, 2011

Continuing this morning on the landing gear weldments I torqued all the bolts and striped them with torque seal. In this photo you can see the AN3 bolts that come in from the left side of the fuselage.

In this view you can see the AN4 bolts that attach the weldment to the main spar. It is nice to have this milestone completed.

Next on my list to do is to install the static ports and lines to the Dynon ADAHRS which will mount in the aft fuselage. I am using the SAFEAIR1 kit that comes with ports, fittings and plastic tubing. I started by marking the fuselage for the holes for the ports. I used the location recommended by Vans but I moved them forward a little to 1.125 inches ahead of the rivet line on the bulkhead to provide enough room for the rear flange of the port. I drilled the holes using a #40 drill then opened them up to .250 using a unibit. As you can see I scuffed up the interior surface of the skin because I will be bonding the ports using ProSeal.

I installed the tube fittings onto the static ports first to make sure I bonded them in with the orientation correct. It’s kinda nice that these fittings come with some kind of sealant applied on the threads so you just screw them in. Then I buffed the surfaces of the flanges with scotchbrite and cleaned them with MEK. I mixed up a small batch of ProSeal and applied a thin layer on the flange surfaces and put them in the fuselage orienting the fittings angled toward the bulkhead where the line will run. I taped them in place to hold them while the ProSeal cures which will be a while because it has been in the 50s and 60s in the garage.

Here is what it looks like from the outside. Very clean and yes it is supposed to protrude out from the surface of the skin slightly.