Author: Joe Wagner
Edition: Model Aviation - 2004/11
Page Numbers: 78,79,80
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The Engine Shop

Joe Wagner 212 S. Pine Ave., Ozark, AL 36360

The Rossi Company and product range

The Italian Rossi company has been famous for high-performance model engines since 1966. Its founder, Ugo Rossi, won several World Championship CL Speed events with his engines. Today the Rossi company, under the management of Ugo's son Alessandro, has been expanding its product line.

Rossi manufactures a wide variety of model power plants—among them some of the fastest-revving car and boat engines ever made. Some of these turn more than 40,000 rpm! For RC model airplanes, Rossi offers an exceptionally large selection, including:

  • Pylon Racing engines
  • Helicopter power plants
  • Ducted-fan engines
  • Several sport RC types

These RC engines range in size from .21 cu. in. (3.5 cc) to .67 cu. in. (11.0 cc). For example, three basic “.60-size” Rossi RC engines are available. They all use the same case but have different bores and strokes: two .60s (long and short stroke) plus a long-stroke .65. Rossi also offers options such as side or rear exhaust, mufflers, and tuned pipes of various kinds.

Examination of the Rossi 35R60-2 (.60, long-stroke)

I was sent one of the long-stroke Rossi .60s (Model 35R60-2) to examine and experiment with. Before I got it, this engine had used more than three gallons of glow fuel—nearly all of that burned in flight while spinning a 12 x 12 APC propeller. I was curious how much wear the Rossi's internal parts would show after that service, so I took it apart.

  • Aside from minor scuff marks at the top edge of the piston, I couldn't find any signs of wear.
  • There's no noticeable play at either end of the connecting rod.
  • The double ball bearings seem like new.
  • The piston-to-cylinder fit, though quite free, provides a “snappy feel” as good as that of any other model engine I own.

The 35R60-2 is massively built. It weighs 22 1/2 ounces without propeller or muffler. The muffler adds another 4 ounces and has an unusual, flexible design.

Muffler design and mounting

Rather than being rigidly attached to the engine, the muffler is a slip fit over a tubular adapter at the exhaust port. It is retained by a miniature “screen-door spring” that passes around the engine cylinder and hooks onto a steel retaining washer on the muffler. Sealing is provided by a high-temperature O-ring on the adapter.

I admire the ingenuity of this arrangement for several reasons:

  • It helps prevent crash damage because the muffler can flex instead of exerting extreme leverage on the engine in a hard landing.
  • The muffler is almost 10 inches long and roughly 1 1/2 inches in outside diameter. If solidly attached, it could cause serious damage in an “unplanned landing.”

This flexible mounting does require a separate attachment to the airframe, but that’s a minor and easily solved problem. I can mount this Rossi as a sidewinder, with the muffler extending back under the fuselage bottom—possibly anchoring it to the tempered-aluminum landing gear.

Carburetor and performance

Rossi uses a ruggedly constructed two-needle carburetor. One minor issue I encountered is that the idle needle is quite sensitive—an eighth of a turn either way makes a noticeable difference. Because my fuel-tank arrangement differed from that of the airplane the Rossi .60 came out of, I had to fiddle with the idle needle to get consistent throttle response from minimum to maximum speed. Changing propellers also affected the settings.

With a 12½ x 6 Graupner propeller and 10% nitromethane fuel, my Rossi .60 turns 12,200 rpm maximum and idles reliably at 2,300 rpm. It hand-starts without trouble—although I do wear a heavy leather glove when starting it.

Rossi and NovaRossi

An interesting sidelight: the original Rossi company was a cooperative venture of Ugo Rossi and his brother. After several years they disagreed, and the brother left to start a company called NovaRossi (“New Rossi”). Today NovaRossi makes its own line of high-quality model engines.

Importers, web resources, and contacts

  • Rossi U.S. importer: SG Model Engines

Box 280303, Northridge, CA 91328 Tel.: (818) 472-8460

  • NovaRossi U.S. importer: Allen Worley

7477 Wood Rail Cove, Memphis, TN 38119 Tel.: (901) 755-1536 Web: www.planethobby.com

After Run Oil (A-R-O) — shop use and engine restoration

In an earlier column I mentioned my liking for Hobbico’s After Run Oil (A-R-O). Lately I’ve been using it as an all-purpose oil in my shop because:

  • It won’t thicken with time the way 3-in-1 oil does.
  • It combines the functions of a rust preventative, a light lubricant, and a penetrating oil.

A practical example: my friend Ron Parker (Houston, TX) sent me approximately 40 old CL engines for a local youth model-airplane program. They had been stored, untouched, for decades and were gummed up solid with congealed oil—none could be turned by hand.

Instead of disassembling and solvent-cleaning each unit, I removed the plugs and liberally doused all openings with A-R-O. In an hour or two the congealed castor oil between moving parts softened enough that I could turn them over. I applied more A-R-O and flipped the propellers while holding the engines nose-down; crankcase compression forced the A-R-O out through the main bearing and rinsed away sticky sludge. Freeing the 40 engines this way took far less time and trouble than disassembly, and it worked very well.

Mini-engine interest and the Cox .010 exhaust throttle

Although most small RC model airplanes today are electric-powered, many fliers still enjoy the challenge of mini-engine power. After considerable experimentation, Steve Adams (610 15th Ave., Santa Cruz, CA 95062; E-mail: [email protected]) developed a simple, effective exhaust throttle for Cox .010 engines.

This is not the extensively advertised device from a few years ago that never panned out. Steve’s device is a new concept, manufactured in limited edition. To make the tiny throttles work effectively, he had to obtain custom-made .010 piston-cylinder assemblies from Estes (which manufactures the Cox engine line). These cost $25 each, which increased the selling price of the throttle kits. The units sell for $40 each postpaid and are available by mail order directly from Steve.

I saw a couple of these devices in action at the SMALL (Small Aircraft Model Lover’s League) meet in Little Rock, Arkansas. Installed in attractive 20-inch-span, all-balsa cabin models that Steve designed, the modified Cox .010s performed impressively. I purchased one of the .010 throttle kits and installed it on an original Cox .010. The installation was a bit more of a chore than I expected; after I notified Steve, he told me my unit was an early version and that later units have eliminated the difficulty I experienced.

Transcribed from original scans by AI. Minor OCR errors may remain.