Author: Sal Calvagna
Edition: Model Aviation - 2009/03
Page Numbers: 102,103,104,106
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Radio Control Giants

Byline

Sal Calvagna [[email protected]]

Southeast R/C has XYZs

It’s no secret that our economy is in a recession; discretionary spending is usually the first to be cut. For many readers this means spending less on hobby items, but there are still recession-busting deals to be found. If you need a new gas engine for a project, check the offerings from Southeast R/C Engines. Their line of XYZ gas engines comes complete with ignition module, muffler, and mount at attractive prices.

Southeast R/C Engines, located in Jacksonville, Florida, is the importer and distributor for the XYZ line of small two-stroke, gasoline-powered power plants. The company tested many small two-stroke engines before selecting the XYZ. These engines are manufactured to high standards using billet aluminum and CNC machining for the crankcase. They start easily, have very little vibration, and idle at 2,100 rpm right out of the box.

On the test bench, a 50cc engine ran more than 10 hours at 3,000 rpm and, when disassembled, showed it was just beginning to break in: bearings looked fine, there were no misalignment marks or loose bolts. The same procedure was repeated for the 26cc engine with similar findings.

Engine specifications and pricing

  • 26-C: short-stroke, big-bore two-stroke. Compact design with a 45° offset spark plug, Walbro WT-793 carburetor, and weighs 2 lb 8 oz (including muffler and ignition module). It will swing an APC 16 x 8 propeller at 7,600 rpm and is rated at 2.5 hp. Street price: $209.95.
  • 50-A: 50cc displacement, rated at 4.5 hp. Street price: $259.95.
  • XYZ-50-HP: newest high-performance offering from Southeast R/C.

For more information, visit the Southeast R/C website.

Rich Uravitch and the OV-10 Bronco

Rich Uravitch is a familiar name in the RC industry with more than 40 years of experience. His background includes service in the Air Force, editorial director, editor-in-chief, author, model designer, design consultant, Top Gun competitor, and Top Gun craftsmanship judge. Rich now focuses on designing models that can use electric power because of the potential it offers scale modelers.

One of his latest designs is an IMAA-legal OV-10 Bronco:

  • Wingspan: 81.5 inches
  • Length: 79.5 inches
  • Wing area: 1,215 sq in
  • All-up weight: 15–19 lb
  • Power: two .46–.60 glow two-stroke engines or equivalent electric power

For more information, visit Rich Uravitch’s website.

The Bronco: origins and service

In the early 1960s the Marine Corps sought a reconnaissance/light attack aircraft capable of operating from unimproved fields. In 1963 a triservice specification (Army, Navy, Air Force) called LARA (Light Armed Reconnaissance Aircraft) was issued. Eleven proposals were submitted; North American Rockwell’s NA-300 won the bid.

Although originally envisioned as a small, simple lightweight aircraft (about a 20-foot wingspan) able to operate on roadways and in jungle conditions, the final Bronco grew much larger: about a 40-foot wingspan, 1,000-pound rough-field landing gear, full electronics, ejection seats, and an empty weight of roughly 7,000 lb that required runways. Despite its increased size, the Bronco had great potential.

Mission capabilities included observation, forward air control, helicopter escort, armed reconnaissance, gunfire spotting, utility roles, and limited ground attack. The USAF primarily used the Bronco as a forward air control aircraft, and it was also useful for low-level aerial photography and aerial radiological reconnaissance, among other roles.

  • First combat deployment to Vietnam: July 1968
  • Last Broncos decommissioned: 1995
  • Approximately 300 built

Ethanol in gasoline and effects on small engines

Most fuels sold today are E10 (10% ethanol, 90% gasoline). Some states mandate its use (e.g., New York, Connecticut, California), and E10 is becoming more common nationwide. In the near future it may be more difficult to find regular gasoline; pilots and modelers may need to purchase Avgas at airfields, which contains no ethanol.

Background on ethanol:

  • Ethanol (ethyl alcohol) is produced by fermenting materials containing starch or sugar; in the U.S. corn is the primary feedstock.
  • A bushel of corn yields about 2.5–2.7 gallons of ethanol.
  • Adding 10% ethanol increases gasoline octane by about 3 points and adds oxygen, which helps gasoline burn more completely and reduces some emissions (notably carbon monoxide).

Concerns with E10:

  • Ethanol is hygroscopic (it attracts water) and is a solvent. It can carry water into fuel systems, which may gum up carburetors and promote rust inside engines.
  • Small two-stroke engines carry lubricant suspended in the fuel/air mixture. Water in the mixture can disperse the lubricating oil before it reaches critical components, causing rapid wear and possible failure.
  • Small-engine repair shops have reported increased fuel-related problems that they attribute to ethanol blends, including gummed carburetors, internal rust, and lubrication issues.

Counterpoints:

  • Ethanol trade groups report extensive testing showing no adverse effects on small engines with E10.
  • Some large equipment owners report long-term use of E10 with no problems.

Practical advice is to consult and trust experienced fellow modelers and maintain your equipment carefully.

Federal study

A “Federal Study on Ethanol in Small Engines” was released on December 3, 2008 (136 pages) and is available online.

Maintenance tips for two-stroke RC engines

  • Replace fuel tubing in your tank and the lines to the carburetor annually. Tygon and Aerotrend lines harden over time.
  • Ensure the fuel pickup line and clunk remain flexible so the clunk can droop and reach fuel in all attitudes. Hardened lines may stand rigid and cause fuel starvation during inverted flight.
  • Inspect carburetor gaskets and diaphragm gaskets. A hardened diaphragm can prevent proper fuel pumping; replacement gaskets are available at lawnmower shops or hobby stores that specialize in gas engines.
  • Check and clean the small fuel screen that traps particles from the tank to keep fuel flow unobstructed.
  • Regular inspection and preventative replacement of perishable parts will extend engine life, especially when using ethanol-blended fuels.

Sources

So ends this month’s column. As always, comments, suggestions, and photos are appreciated. MA

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