Sanded and Applied Primer to Gear Fairings – 8 hrs

Sunday Mar 16, 2014

Continuing to work on my gear leg fairings, I applied a layer of epoxy/micro to the nose gear upper intersection fairing to smooth out some of the waves and irregularity that came with the layup over the modeling dough. That, of course, was followed by lots of sanding. One coat got me 90% of the way there, so I applied more micro in a few spots to finish it off. Here is the end result, ready for a coat of primer.

Next I installed the right brake hose and taped it to the gear leg with split tygon tubing spacers at each end and the middle.

One more check of the fit of the right leg and wheel fairings to confirm that this set is ready for primer.

An optional step was to mold a little aerodynamic lip onto the front shell of the nose gear fairing where the cutout is for the strut. This directs the airflow up around the strut instead of directly into the slot. I applied a layer of packing tape to the cutout to form a ramp and then two layers of bidirectional cloth to start and let that cure in the basic shape. Then I applied a fillet of epoxy/micro along the front edge and smoothly blended that out on the side. This only took one iteration of sanding to get a decent shape.

Here is a side view of the front shell where you can see the smoothly blended lip.

Next came a major primer session. I used UV smooth prime which is thick and a pain to spray but it cover pins holes better than Ekoprime and provides a UV barrier for the fiberglass. It also sands easily and gives a really smooth surface. I had to load my spray gun several times to get all eleven of these part primed including the empennage fairing which has been sitting around a while waiting for primer.

Here is another close up view of the nose gear fairing front shell where you can see how the lip turned out.

3/23/14 Update: Here is how the nose gear upper intersection fairing looks after I match drilled it to the cowling. I still need to install nut plates on the cowling and countersink the fairing for flat head screws.

 

Started Fitting Main Gear Fairings – 5 hrs

Sunday Feb 2, 2014

This morning I fit the front and rear sections of the main gear fairings together. The joint required some work to get an acceptable fit. The rear section seems to be molded on a tool pretty accurately but the aft edge of the front sections were not straight resulting in gaps in the seams. I sanded the high spot off to get a good fit on one pair. The other pair will require some filler in one particularly low spot. I drilled and cleco’d the section together.

Based on a tip from Bruce Hill I trimmed the opening for the tire to enlarge it slightly and to even it out a bit. This photo shows the trim lines before I opened it up.

I installed the U-808 brackets for the fairings on the wheel nuts and taped a 1-inch thick block of wood to the top of the left tire. Then I began fitting and aligning the wheel fairing. Initially the fairing would only go on until it bumped into the gear leg but I marked the location and notched the fairing until it would go far enough forward to align with the U-808 bracket. This overall seems to fit better than the nose wheel fairing.

Here is a view head on to the tire. Notice that the angle of the fairing matches the camber of the wheel so the fairing is tilted outward relative to the ground. There is also a bit of toe in of the tire but the fairing is aligned to the free air stream which is parallel to the aircraft center line which is denoted by the blue tape. The U- 808 bracket actually fits pretty well.

When the fairing was aligned to as well as I could make it I drilled through the fairing into the predrilled holes in the U-808 bracket which I could see pretty well through the translucent fairing.

Then I put the forward section of the fairing on and continued to tweak the alignment to make the axis of the fairing parallel to the tape line. This is hard to judge because the fairing is tilted outward but I got it aligned as well as my eye could judge. Then I drilled through the fairing into the U-810 bracket holes on the inboard side. Afterward, I marked the opening around the tire and trimmed a little more away for clearance. It is getting close but I am still not done there.

I did not take a photo in process but I also countersank and riveted the hinge in the nose gear leg fairing. I installed it to see if it fits with the anti-splat mod installed on the leg. Thankfully it just fits.

Preparing to Lift the Airplane – 6 hrs

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.

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.

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

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.

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.

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.

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.