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Nose Ring Installation
The nose ring is a very important part of your soft mount installation. It serves multiple purposes, including keeping your painstakingly set thrust settings constant and eliminating throttle changes when you pull "g"s. They also keep the engine from thrashing about and banging up your airplane as much as they would without a nose ring. All in all they are a "must have" accessory if you use a soft mount.
There are many ways to install and set up a nose ring. After having done several such installations over the years I finally decided to ignore all of the instructions I'd seen and just sit down and figure out how I'd prefer the thing to work for me. I want the nose ring to be very stable and firmly installed, but I also want to be able to install and remove the engine without needing to be a contortionist or having to carry special tools. Since removing the engine on most pattern planes requires that you first remove the nose ring, the nose ring itself needs to be easily removed. And that was where the other installation methods had let me down. (Especially if you needed to pull an engine in a hurry at a contest and the thrust washer had stuck in place!)
So, here's my method. I've used this on my last 3 planes and I can't really see any reason to change it. It works great, is extremely rugged and is easy to install and to remove.
There are three components involved in this installation. For the actual nose ring I use the CFE drilled nose ring. I've found these to be a perfect fit for the YS engines and they are a very long-lasting device. The nose ring is glued, using Zap-a-dap-a-goop, to an end grain balsa/glass laminate piece that is shaped to fit inside the nose of the airplane (allowing movement in all directions to align for installation) with a hole cut in the center to allow the nose ring to fit inside. (Do seal all edges of this laminate with CA to keep fuel from seeping in.) This assembly is "spaced" from the nose using two pieces of 1/8" ply on each side. See photo
The first step in installation is to prepare the nose of the plane for gluing in two of the 1/8" ply spacers. Remove any ugly bumps on the back side of the nose and bevel the spacers as needed to get a good glue joint with both the front of the fuselage and the sides. Scuff and clean the glass per normal and then use slow epoxy and milled glass as needed to get a good glue joint for the two spacers. Clamp and let cure. See photo 2.
Now you need to drill the first (front) spacers for the retaining bolts. Use the nose ring/laminate that you prepared to figure out where to drill. It's best to install the engine on the mount and the plate on the engine for this. (Oh yeah - you have to have installed your firewall and mount before starting this project!) You want to have the holes miss the aluminum, and you want to leave at least 5/32" of the balsa/glass material outside of the hole. DO NOT drill the balsa/glass at this time, just use it to position the holes. When you have the hole locations marked, drill a hole through the nose and the first set of play spacers (ONLY!) that is big enough for the HEAD of the bolt you'll be using to pass through. (That's right, the head). I use 4-40 bolts. (see photo 3).
Next we install the second set of 1/8" ply spacers. I cut these down to about half the size of the front set. Fit these spacers approximately centered on the holes you drilled, and use slow epoxy to glue in place. When cured, use a dremel and grinder to get rid of as much of the excess spacer material as you can to clean up the installation and minimize weight. (Photo 4)
Now comes the part where you have to get things perfect. Use a GOOD center locater such as the inexpensive "Dead Center Hole Locater" from Great Planes to mark the center of the holes you drilled in the front spacers onto the rear spacers. Now use a bit just big enough for the SHAFT of the bolt to go through and drill the rear spacers (only). Leave that bit chucked up, you need it one more time. At this stage you can push the bolts into the front spacers so that the heads are recessed beneath the nose of the plane behind the spinner. The heads stop against the front face of the rear spacers. All that's left is fitting the actual nose ring.
Re-install the engine (AND the nose ring plate! Make sure that the o-ring side is facing forward.) and align it to perfection. The easiest way to do that is to use a thin ply spacer cut to match your spinner backplate, with slots or cutouts in it that allow you to access the holes you have drilled. Slip this over the crankshaft and tighten it down with spacers and the prop nut, then position and tack glue it in place.
Now hold the nose ring and laminate assembly firmly in the desired position and drill one hole with the bit you left in the drill from the last step. Carefully feed the bit through the hole you drilled in the rear ply spacer and - holding the drill perpendicular to the hole - drill through the laminate that you glued the nose ring into. Push a long bolt through this hole from the back side and temporarily snug it down to hold the nose ring assembly in place. Re-check the alignment of everything, then drill the hole in the other side of the assembly.
Remove the engine and nose ring assembly. Put blind nuts on the back side of the balsa/glass laminate in the holes you just drilled, and spot some slow CA on them as you tighten them into the wood.
Guess what? You're done! Slip the nose ring assembly on the engine, put the engine back in the mount and stick the bolts in from the front and snug them up. You now have a nose ring that is perfectly aligned, that can be installed and removed without having to get inside the engine compartment. Just pop the spinner off and there are the bolts. You can't remove it without removing the engine - but then why would you? I've never had to do any sort of maintenance on this nose ring assembly. The final assembly is shown in photo 5. All that's left in this case is some cosmetic filling on the left side of the nose where the kitmaker knocked out a bit more glass than needed, then it's ready to run!