·:[ Darryl's Coot Building Journal ]:·
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I had an aviation mission today. Namely, testing out a second-hand piece of avionics (a Narco NAV 121 VOR reciever W/CDI) that is going into the Traveler project. Today was a knock-out stunningly beautiful day here in the Pacific Northwest (on the heels of a nasty March), such that, 6 hours later, I still haven’t managed to wipe the smile off of my face.

Anyway, here is the video of the test:

[1.5 hrs] The nosewheel assembly, as it came with my parts Coot, looks like this:

I disassembled, cleaned, and inspected the parts for this assembly. Clearly, the tire and innertube should be replaced. The nylon hub is in acceptable shape. Some builders have gone to an aluminum hub (e.g. Andy Adams’s hub).

Here are the parts following disassembly and some cleaning. Clearly some sandblasting is in order!

(Someday they will look like Andy’s pretty parts.)

[2 hrs] Cleaned up the nosewheel box a bit and cut and glued in the horizontal spruce blocking along the top. The wooden part of the box is now complete. The hardware stills needs to be sandblasted and painted for final assembly.

[4 hrs] The nosebox is nearly complete. I drilled and glued on the bearing stiffeners. Each bearings on the right side required a 0.032 shim to sit flat on the vertical spruce support, so I cut and glued on a spruce shim. Finally, I drilled all the bearing mounting holes. Here is the final assembly:

Yes…there are two bolts not installed on the lower bearing. The temporary assembly was done with the old bolts, washers and nuts, which will be replaced later. The previous builder had used the wrong length bolts where the bearings are bolted into the plywood sides. AN3-10A bolts are required there.

In the previous post I mentioned modifying a drill bit to fit into a Dremel tool collet. This was in order to use a Dremel 90 degree adapter to drill between stations 7 and 14 into in the vertical spruce support. I wanted to use a drill—not a Dremel tool—with the 90 degree adapter because a Dremel tool is too low torque and too high an RPM. (The 90 degree adaptor doesn’t fit my Craftsman rotary tool anyway.) So, I cut away the plastic where it mounts to the Dremel tool (at the bottom of the photo). There is a square drive that fits a square-hole chuck on the Dremel tool.

I simply inserted that square-hole chuck into the chuck of an ordinary drill, and used it to drive the right-angle adapter. The drill bit was ground down in a lathe to fit the Dremel collet. It worked great, and I am sure this tool will save me from much aggravation elsewhere on the Coot.

[2 hrs] This weekend I prepared surfaces, did a little trimming and then glued up the nosewheel support bearing and gear retraction bearing stiffiners.

One of the problems I also dealt with is finding a way to drill the holes through the vertical spruce stiffeners for mounting the two bearings. The chuck on an 90 degree drill attachment was too wide. However, a dremel 90 degree attachment just fits. So, I spent some additional time mounting a Dremel tool to my lathe tool post, and used a small diamond grinding wheel to grind the shaft of a 0.1900 drill bit (I have many of these thanks to Boeing Surplus) to fit the Dremel collet.

The work that is still needed for this assembly includes:

• Drill holes for bearings
• Glue in a few horizontal spruce stiffiners along top of nosewheel box (I’ve left them out for drilling access)
• Sandblast and paint bearings
• Cut Teflon inserts for the nosewheel support bearing (I have the material already)
• Order and install O-rings (AN6227B-25) in nosewheel bearing
• Install bearing assemblies

[0.5 hrs] If you look carefully at the top photo in the previous post, the nosewheel retraction arm bearing (#618) hangs over the edge of the vertical support (horizontal in the photo). It hangs over because it is spec’ed at 3/4″ wide on a 3/4 wide piece of wood, but there is a 1/8″ stiffener in there, too. Yesterday I trimmed the excess off in a milling machine. (Yes…using a milling machine is overkill, but I needed to repair the motor variable speed control on my milling machine and tram the head, so this gave a reason to do it.)

While I was at it, I added corner radii on the #618 bearing and the #616 nosewheel support bearing. My Coot will be a few grams lighter as a result.

[4 hours] I salvaged much of the hardware for my Coot from a previous builder. One difference between my nosewheel box and the previous builder’s is that the previous builder used 1/2″ spruce framing for the bulkheads at stations 7 and 14, whereas I used 3/4″ spruce frames (see this post for a look at the old nosewheel box). In order to preserve the exact same geometry for the nosewheel and the nosewheel retraction arm, I had to cut a 1/4″ slot in station 14 framing for the #618 nosewheel retractoin arm bearing. I chiseled that slot in the frame, and shaped and drilled the 1/8 marine plywood (MPW) (lateral) and 1/4 MPW (medial) stiffeners for both the nosewheel retraction arm bearing (#618) and the nosewheel support bearing (#616). (Click on photos for a larger version.)

In this photo, the two bearings with stiffeners in place can be seen. (I haven’t glued these in yet.)

In the following two photos, the assembly can be seen temporarily assembled with the nosewheel and the retraction mechanism. The hardware is quite ratty, and needs to be sandblasted, inspected and repainted.

The fully retracted nosewheel gear self-locks over-center, so that the nosewheel is fully supported vertically in the inverted, level nosewheel box.

The nosegear retraction arm (#619), seen in the lower part of the assembly, is not built according to Molt Taylor’s original plans. Rather, it is the Rufus Howard/Hugh Jones design with a rubber shock absorber. I don’t have the rubber piece yet, but the shock goes where the shiny stripped piece of metal is seen (it’s a collar from a broken drill chuck).

The bottom photo shows the nosewheel in the fully retracted position.

[2.5 hours] Cleaned the inside of the hull today. I used acetone to remove 20 years of grundge. Next, I used an engine cleaning wand (low pressure sprayer) to wash down the entire inside of the hull with diluted Simple Green, followed by a second spraying with water.

I also began removing the old tape from the Keelson. The fiberglass tape had delaminated from the wood, which had evidence of wood rot in some spots. It will have to be replaced.

[5 hours] After gluing up the sidewalls of the nose wheel box, I realized that one of the walls was misaligned. Ugh! I spent several hours last month chisseling out the old plywood and cleaning up the spruce. I then cut out a new piece. Today I finally got around to gluing the new side wall in.

I also cut out the 1/4″ and 1/8″ marine plywood stiffeners to go around the axles of the nose wheel and the retraction mechanism.

Finally, I disassembled the gear retraction mechanism that resides in the nose box for sandblasting.

[2 hours] Drilled the holes in the nosewheel box sidewalls for the nosewheel axle bearing and the retraction arm bearing. Assembled and clamped the entire assembly and then disassembled everything to glue entire box together.

[3.0 hours] More work on the nosewheel box work. I did the final shaping of the sides of the wheel box, cleaned up the individual frames, and cut spacers for gluing the final box up.

[2.0 hours] I glued the last two vertical blocks on the rear of station 14 (215-4 rear) today. I also cut out the two sides (215-8) for the nosewheel box.

The next step for the nosewheel box will be to assemble stations 7, 14, and 22, sides and a couple small pieces of blocking into a box. A couple of 4″ wide pieces of 1/4″ marine ply wood (MPW) are required to finish the assembly. Rather than cutting up my beautiful, unmolested sheet of 1/4″ MPW for these small pieces, Russ Milham has offered to donate some of his stock.