The 1st ARF Nobler I did back in 2002 has been hanging engine-less on a garage wall the past several years. It was originally set up for a Stalker .40 RE and flew 4 years with that engine before I partially wore it out. I had two other Stalker .40 REs, but they never worked out as well as the first one. I sold all 3 of those engines to raise cash, so the model was relegated to "display status".

In mid July I moved the Nobler to the shop to get it ready for eBay. Its fully take-apart and can be shipped domestically at reasonable cost. Before selling it, I decided to take a shot at reworking the nose for a Stalker .46 RE. Due to a combination of health and personal issues, the project took 10 weeks! The engines look similar, but the .46 case is wider and the muffler design is different. At one time Stalker offered 4 styles of muffler compatible with the .46 RE. The smallest (short neck, short body) is the only one that fit the Nobler, without completely reworking the landing gear mount. I always wanted to try this engine with muffler pressure, so I tapped the neck for a Du-Bro unit and glued it in place with JB-Weld. The plumbing and fill procedure is complicated but workable. 

Part of the rework involved a glassing and refinishing of the engine and tank compartment along with spot repair and repainting of the cowl. I wanted to ensure a solid mount for the .46 and make sure the model still remained marketable after many more flights (it has about 500 on it now). I also decided to Monokote all 5 of the tank shims. They were getting a little fuel soaked and it was easier to cover them vs. making replacements. The Monokote went on fine, despite some oil soakage.

A new anchor for the rear exhaust muffler had to be designed and fabricated. The .40 used a longer pancake style muffler with a metal tab at the rear. The same 4-40 bolt that holds the landing gear cover in place, also passed through a hole in that tab to anchor the muffler. With the .46 I'm using a short tube muffler with no tab. To speed up the project, I adapted a leftover fixture from the Score and added maple block hard points as screw holds. Stalker mufflers attach via an O-ring and press fit. They depend on some structure in the model's nose to keep them from blowing off when the engine is running.

I have about 8 hours of run time on the Stalker .46, but have not flown it in many years and can't recall how it ran in the air. It runs great on a test stand, but I was anxious to revisit it's airborne performance. I also wanted to try running with muffler pressure which I've never done before with any the the Stalkers. Another issue is fuel economy. Would the .46 run long enough to fly the pattern on the Nobler's 4.5 ounce tank? The LA .46 does, but I always run those on muffler pressure. If Nobler No. 1 and the Stalker .46 RE work out out as a pattern flying combo, I will sell neither plane nor engine, at least not immediately.

Performance Update:

I got 4 flights in on 9/24/12. Weather was good, but wake turbulence was an issue due to almost calm air. Lines were .015" X approx. 62 feet eyelet to eyelet. The first flight was on Sig 5% Castor/Klotz blend with an 11 X 5 Zinger prop. It felt and sounded good from the start. Run time was short (just under 5.5 minutes) due to a slightly rich needle and possibly a less than full tank.

Flight 2 used the same fuel & prop with a slightly leaner setting. I did all the pattern maneuvers with only one lap in between. Run time was just over 6 minutes (a "pattern length" run) and the engine sounded great. Flight 3 was on 7.5% fuel and the same needle setting. Surprisingly, run time was about the same with just a little more "zip". I did the whole pattern with double laps between maneuvers. On the 4th flight I changed to an 11 X 6 Zinger with 7.5% fuel and the same needle setting. The engine was now loading more and the plane noticeably faster, with more line tension. Run time was over 6.5 minutes.

Run quality depreciated on subsequent flight due to filter plugging. Stalker mufflers are assembled with a high temperature glue which holds them together OK. But under constant attack from hot exhaust fumes, some glue particles eventually flaked off, clogging the fuel system. I suspected this might happen and was not too surprised when it did. Back in the shop I flushed the tank and filter screen and re-plumbed the uniflow line for suction (as it was originally set up). Since shop and field time are very limited, I don't have the "luxury" of making only one change at a time, so I made several. I pulled the rear cover plate and flushed out some epoxy particles, then replaced the Mylar gasket with a Teflon one. A smaller ID venturi was installed (to draw better without muffler pressure). I also added a second head shim.

On a nice day in early October, it took 2 flights to get a good needle, but then settled into a very smooth, mellow and repeatable stunt run. It actually breaks better with the smaller ID venturi on draw vs. a larger one on pressure. Fuel economy is great (less than 4 ounces for the pattern with several laps to spare). Filling the tank is also far easier. I went back to a Zinger 11 X 5 prop on 7.5% nitro fuel (50/50 Castor/Klotz). As long as the power output can be tweaked and "mellowed", a light weight .46 is not too much engine for this model. I'm very happy with my other 2 ARF Noblers the are now powered by LA .46s.

I'm glad I did the rework necessary to mount the Stalker .46 and I'm pleased with its in flight performance. It's milder than the LA .46, probably due in part to back pressure created by the short muffler. However, it delivers plenty of power for the Nobler and would easily fly a larger model like the T-Bird II, Skylark II or Chipmunk. Its a little smoother running, very quiet and the plane stays cleaner due to the rear exhaust set up. I look forward to flying the combination this Fall and in area contests next season if its still around. Regards, EWP

That is amazing what one can do when their mind is put to it.   Thanks for all the info.