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Archive for January, 2014

Preparing to Lift the Airplane – 6 hrs

January 26, 2014 Leave a comment

Sunday Jan 26, 2014

In order to fit the wheel pants and align the gear leg fairings to the direction of flight I need to lift the airplane off the landing gear. The gear legs deflect under weight and the angles relative to the fuselage change. So I started investigating options for lifting the fuselage a few inches and take the weight off the gear. If the wings were installed I could make some jacks that lift at the tiedown ring points along the main spar but that is not an option in the garage. It would be too much trouble to rearrange the garage and install the wings just for this task. So I spent some time Saturday working on a design for some cheapo jack stands I can put under the fuselage at the wing spar. The photo below shows my progress in building them. The raw materials cost me less than $20 for these. The 4×4 columns will support the weight with four diagonal braces on each one to carry lateral loads and keep the columns from tipping over. The stand on the left has a 9 inch long 5/8 inch diameter threaded rod installed with nuts and bearing plates which will allow me to jack up the upper bar by several inches. I still need to screw together the right stand and install the threaded rod. More to report later when I set this under the spar and see how it works. I estimate that the airframe weighs about 800 lbs right now and the c.g. should be slightly in front of the main spar so I will use my engine hoist to lift at the front to take weight off the nose wheel.

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I also worked on wiring the nav/position lights through the wing. I installed a 4-pin molex connector on the wires of the Aveo Aurora light and ran a twisted shielded 3-conductor wire through the wing conduit. I terminated the wire on a mating 4-pin molex connector for the light. I also made a small aluminum clip to hold the connector on the wing rib and keep it from rattling around. The connector can be easily slipped out of the clip to make installing the wingtip easier.

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Categories: Gear Fairings, Wing Tips

Wrapping Up Wing Tips, Progress on Nose Wheel Fairing – 9 hrs

January 19, 2014 Leave a comment

Sunday, Jan 19, 2014

The fiberglass stiffener I laid up inside the right wing tip had cured for 24 hours so I gave it the push test. Sure enough, the flexible region on the bottom was much stiffer and the tendency to oil-can was gone. So I removed the wing tip from the wing and inspected it inside. All looks good. I might paint on one more layer of epoxy just to finish it but I would say the experiment was successful so I will do the same to the left wing tip.

On the other wing tip, the Pliobond was pretty well set up by now also so I removed the tape on the reflector, pulled off the plastic film and installed the lights. I also riveted the hinges to the fiberglass. That took a while because I had to clean the epoxy out of the holes and countersinks. I riveted the aft aluminum rib in place and bent and cut the hinge pins to final length. Except for adding the internal stiffener, this wing tip is done. I am ready next to install connectors and wire both wing tips up through the wings.

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I refocused my efforts on the nose wheel pant and leg fairing. On the first try to install the aft section of the wheel pant I found it to be extremely tight and the opening for the tire was too small on the aft end especially. I did a rough marking being conservative on the first try and starting trimming. Here is the first marking.

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Once I trimmed the aft section of the wheel pant enough to fit roughly close to the final position I cut a notch in the front section so I could mate the two sections together. To get the pant level I put a piece of electrical tape down the side with the lower edge aligned with the centerline at the nose and the aft end. That made it easier to measure the height above the floor at the front center and aft ends. The plans say this height should be 6-13/16 inches and immediately I saw that that was going to be difficult. The pant naturally wants to sit lower than that and it looked too high compared to the drawings. That is when I noticed a small note on the drawing that said the dimension is with no deflection in the tire – i.e. no weight on the wheel. They also showthe axle height which is 5.5 inches. I measured mine at 5.1 inches with weight on the tire. That 0.4 inch difference made a big difference in the fit. I adjusted the 6-13-16 inch dimension to 6.41 inches to compensate and was able to align it to that position relatively easily with a 0.5 inch wood block spacer on top of the tire. It now looks pretty similar to the position I have seen on other finished RVs.

I also installed an Anti-Splat nose gear stiffener I ordered to help address my concerns about the infamous tip-over issue of A-models that is well documented. This is not the perfect solution to the problem but there is evidence that it helps so I spent the extra $350 as insurance. Installing this thing was a bear. I won’t go through all the details, but getting the clamp installed over the gear leg took quite a while and some elbow grease to get it bent into final shape close enough to get the screws installed with the stiffener bar. Here it is installed although the position along the leg needs to be lowered slightly toward the wheel pant.

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Next I worked on the fit of the gear leg fairing, trimming both the top and bottom ends to get a good fit. I wanted the Anti-Splat device installed to make sure the fairing would fit over it as advertised and to be able to make any small adjustments to position to facilitate that. There is still a lot of work to do on the fairing and the wheel pant but this is not a bad start.

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Wing Tips Again, Started Nose Wheel Pant – 9 hrs

January 18, 2014 Leave a comment

Saturday Jan 18, 2014

One thing I noticed about the fiberglass wing tips is a flexible area on the bottom surface where the curvature is slight. It does not take much force to oil-can the surface. I guess that’s why some builders add stiffeners inside the wing tips. I decided to give it a try on the right wing tip so I cut a 2 foot by 1/2 inch wide piece of foam core and laid two coats of 9 oz fiberglass cloth on it. I goes across the flexible region. The foam core was wet with epoxy first then two layers applied over it and flared into the surface.

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Then I put the wing tip back on the wing to cure to make sure it sets up in the installed shaped.

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Back to the left wing tip I cut the opening for the LED light just like I did for the right light. After smoothing all the edges I installed the light to make sure it is centered correctly.

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Then I took the light back out and made a reflector plate out of .025 aluminum Alclad sheet. This is time consuming because the shape is cut specifically for this wing tip. I taped the reflector in place and marked the light opening from the inside and cut that to match. When everything seemed to fit right I bonded the reflector to the fiberglass tip using Pliobond. I taped it all down to allow it to dry for 24 hours.

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Since I was waiting for glue to cure on both wing tips I started work on the nose wheel fairing bay fitting the two pieces together and drilling holes in the flange to hold them together. This will be my next project.

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Categories: Wing Tips, Wings

One Wing Tip Light Installed – 8 hrs

January 12, 2014 Leave a comment

Sunday Jan 12, 2014

This morning I assembled the Squadron light into the right wing tip. This view shows that I installed the mounting plate first with the springs and spacers and adjusted the angle to get it approximately aligned using my wedge tool for reference. I’ll have to make the final angle adjustments on the airplane after the wings are installed. The mounting plate is surprising stiff in this configuration.

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Then I installed the light on the mounting plate. I decided to reinstall the Baja Design bezel because I like the looks. I could leave it off but I would need new metric screws because the stock screws are countersunk. This light includes a nice waterproof connector already attached and the mating connector is in the box. A nice plus.

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Here is the final assembly with the Aveo Nav/Pos light and wing tip lens installed. I am pretty happy with the results.

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Back on the wing tip  installation to the wing, I primed the modified aluminum ribs and installed this nut plate as a retainer for the hinge pins.

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I made a retainer block for the hinge pins using a piece of UHMW I had on hand. There is a slot in the block that captures the pins which are bent at a 90 degree angle. One screw holds the block down which keeps the pins from moving. I used a temporary socket head screw until I pick up a couple of suitable countersunk screws.

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Categories: Wing Tips, Wings

Details on Baja Light Installation – 8 hrs

January 11, 2014 Leave a comment

Saturday Jan 11, 2014

Here is the detail I promised on the installation of the Baja Designs Squadron LED light into the wing tip. I started by making a mounting plate for the light. It attaches in place of, or under the bezel which I show removed here. The shape is very similar to Mike Bullock’s design as far as I can tell. I wanted to use .062 thick sheet for the mounting plate but I didn’t have any stock on hand so I used two pieces of .032 which I riveted together so it is almost as stiff as a single piece. I traced the cloverleaf opening on the plate from the bezel.

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I installed three K1000-08 nutplates on the plate for the mounting/adjustment screws. I also made a cheapo wooden wedge that matches the nominal angle of the mounting plate relative to the fiberglass tip to aid in alignment.

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Here you can see that I temporarily installed three mounting screws backwards in the plate. Two screws are 3 inches long and the third is 1.25 long. I adjusted the screws until the plate sits at the same angle as the wedge on the bench.

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I put the mounting plate inside the wing tip and placed it as far up into the cavity as I could leaving only a little clearance around the plate. This is to get it as far outboard as I can. Based on that I marked the location where the shorter screw contacted the fiberglass. I messed around quite a bit on the first wing tip to determine where to drill this first hole in the face of the wing tip.

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I drilled the first mounting hole, seen here from the outside.

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Then I placed the mounting plate on the outside of the tip with the outboard screw on the hole I just drilled. I aligned the mounting plate so it is generally square to the wing tip edge and marked the location of the other two holes where the long screws contact the tip.

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Here are the parts that go into the mount. The two long screws and the short screw, three springs I bought at True Value Hardware, and some spacers I made from aluminum tube. The spacers are cut on an angle to sit flush on the fiberglass surface.

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I diverted my attention to the hinge mounting holes for the wing tip so I could countersink them in preparation for reveting.

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The wing rib interferes with the hinges at the forward end so I sketched the profile I wanted on the rib for trimming. To do this I first had to fit check the rib in the wing tip with it installed on the wing in order to get the fore/aft position correct. It needs to just fit snug into the wing tip and you have to adjust the fore/aft position to do that.

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Here it is after the rough cut on the band saw.

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I cleaned it up and bent the flap up on the forward edge to make a new stiffener. I match drilled it to the wing tip.

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Next I mixed up some epoxy and bonded the hinges into the right wing tip. I filled the holes in the hinge with epoxy /flox.

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Then I put the wing tip back on the wing while the epoxy cured. I want the right curvature in the hinges when it sets up. I came back after a couple of hours and swapped out the clecos so they would not get locked in by the epoxy.

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About 8 hours later the epoxy had set hard so I took the wing tip off and riveted the hinges in place.

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Categories: Wing Tips, Wings

More Work on Wing Tips – 6 hrs

January 5, 2014 Leave a comment

Sunday Jan 5, 2014

I have been dreadfully slow in updating my posts lately because so much is going on at home and work. I hope you’ll forgive me.

I am installing Baja Designs Squadron LED lights in the wing tips following the approach pioneered by Mike Bullock but of course there are many dimensional details I had to work out. My initial efforts are focused on the right wing tip and then I’ll apply what I learned on the left wing tip. Since I was focused on figuring out the dimensions for the light mounting plate, the aperture hole in the wing tip and where to install the mounting screws I did not take photos along the way on the right side. I’ll be more diligent to do that on the left wing tip but for now here is the partially assembled result on the right side. I pushed the light as far outboard toward the tip as possible to minimize any shadowing of the beam by the Nav/Pos light as the Squadron points slightly toward the centerline. I calculated I need an angle of about 1.3 degrees to make the beams cross 500 feet out in front of the airplane. That should be the worst case. I may want to extend the crossover point out even further, meaning a smaller angle.

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Looking straight into the aperture you can see the mounting plate cut out to match the Baja Designs light. More details will be posted later.

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I cut out a piece of .025 thick Alclad to make a reflector for the right wing tip lights. I think the shiny reflective surface looks better than a painted surface and it helps reflect light out where you want it to go. I drilled holes for my Nav/Pos light which is an Aveo Ultra Aurora LED light. I glued the reflector plate onto the wing tip using Pliobond stinky glue and I taped the edges down to secure it for a few days while it cures.

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I also started working on installing hinges to mount the tips to the wings. I ordered these from Spruce, again following the lead of Mike Bullock (thanks Mike) who published a nice pdf file showing how he installed his tips with hinge part numbers listed. You can find the document if you Google “mike bullock wing tip hinges”. In this photo I have cut one hinge down to final length and match drilled the inboard side to the wing tip.

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Then I match drilled the outboard half of the hinge to the wing tip. Notice that there is an extra hole drilled between each on the stock holes which are intended for screws. That is to add strength to the riveted joint of the fiberglass to the hinge.

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I flipped it over and repeated the process on the other side.

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Next was the job of cutting the outboard part of the fiberglass tip away to be used as a spacer under the hinge where it mounts to the wing.

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After that, I had to check the fit on the wing to make sure I was going down the right path. It looks good!

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Categories: Wing Tips