Author: Joe Wagner
Edition: Model Aviation - 2006/10
Page Numbers: 102,103,104
,
,

The Engine Shop

Joe Wagner | vecojoe@juno.com

New CL engines from Brodak Manufacturing

Although most of today’s piston-powered model pilots are RC sport fliers, there are still many enthusiasts of CL flying — and their numbers are growing. Much of this enthusiasm has been generated by John Brodak. From his headquarters in Carmichaels, Pennsylvania, John operates the world’s largest CL-model-supply business, and he has continually expanded its scope through the years.

Because few engines designed specifically for CL models are being manufactured anymore, Brodak has entered that product line. To join his earlier-issued Brodak .40, he recently introduced three new smaller engines specifically intended for CL flying: an .049, an .061, and a .25. (A .15 is on the way.)

Common features of the new Brodak engines:

  • Aluminum pistons running in chrome-plated aluminum sleeves (AAC).
  • Rugged construction and attractive appearance.
  • Complete, easy-to-read instruction sheets.
  • No need for high-nitromethane fuel; start and run easily on 10% nitro.
  • Typical operating speeds: 12,000–17,000 rpm for the 1/2As (.049/.061) and roughly 11,000 rpm for the .25 (depending on propeller).

Additional features of the two smaller engines (.049 and .061):

  • Color-anodized cylinder fins.
  • Hardened-steel propeller retaining screws.
  • Well-rounded air-intake openings to minimize power loss from “inlet stall.”
  • High-precision needle valves.
  • Lightweight: the .061 weighs exactly 2 ounces with muffler and propeller.

The Brodak .25 resembles the earlier .40 and shares features such as AAC piston and cylinder, a sleeve-type main bearing, and closely fitted crankcase to maximize fuel suction (CL engines don’t usually use — or need — muffler-pressurized fuel tanks).

More details at: www.brodak.com

Imported model diesels and Carlson Engine Imports

Decades ago the Russians and Chinese began using model-airplane engines as teaching tools in schools, and millions of small model diesels were manufactured for that purpose (for example, the Chinese Silver Swallow .15 and the Russian MK-17 .09). These engines are well made, rugged, start readily, run well, and are remarkably low-priced.

A good supplier for these types is Carlson Engine Imports:

Carlson carries many sizes and types of model engines (including RC) from Great Britain, Russia, China, India, Italy, and more, and sells diesel fuel too.

Fox .049 FAI revival — Doug Martin

Another unusual source is Doug Martin, who has recently acquired all existing components for the 1960s-era Fox .049 FAI free-flight engine and is custom-assembling these in two versions:

  • One version has an engine-mounting tank arrangement on its rear with the same hole spacing as Cox’s Black Widow.
  • The other version lacks that tank mount.

Contact:

The Fox .049 FAI is the only newly made engine available today that is legal for Nostalgia Free Flight competition, and it is a potent power source for that usage. Using techniques worked out by Randall Hopkins, the new .049 FAI engines Doug assembles can compete effectively with Holland Hornets. The Fox’s conservative exhaust-port timing limits peak speed to about 19,000 rpm, but its high torque at that speed permits using larger, more efficient propellers than a Hornet can swing. Careful rounding of the intake-opening edges can boost top rpm enough to make the work worthwhile.

Engine repair and custom tuning — BJ Model Engine Service

Model engines vary tremendously, but they all require maintenance and repair from time to time. Factory service is often unavailable these days, so expert repair and tuning are required. One highly recommended specialist is Bill Jensen of BJ Model Engine Service. Bill does very thorough engine-repair work; he doesn’t work cheap, but his services are worth the cost.

A recent example: I received a used, old-model Enya .09 RC engine (the style without a muffler and with a barrel throttle coupled to a pivoting exhaust baffle). I added a custom muffler, cleaned it up, and planned to donate it to a young RC starter. Although the engine had excellent compression, it would not run right on my test stand. I sent it to Bill Jensen along with the propeller I wanted to use (an 8 x 4 Cox Competition) and information about the fuel I preferred so he could set the engine up for optimum performance.

Bill’s procedure:

  • He wrote a detailed Engine Service Worksheet listing every step, every item supplied with the basic engine, and the status of all major parts (crank straightness, compression, glow plug, etc.).
  • He checked and noted many minor but vital variables affecting performance.
  • He found two discrepancies: the spraybar had been installed too deeply, and my custom muffler had too much exhaust exit area for reliable idling.
  • He corrected those flaws, changed the glow plug, and performed seven separate test runs between adjustments (each noted on the worksheet).

Result: the Enya achieved a top rpm of 11,900 and a reliable idle of 2,000 rpm. The engine was returned with copies of Bill’s worksheets and Enya’s factory data sheet and parts list for that old-style RC engine — a very thorough service.

BJ Model Engine Service contact:

Ohlssons — parts and service for vintage engines

Just before and after World War II, the most popular model-airplane engines in the U.S. were the California-made Ohlssons. Last manufactured more than 50 years ago, many are still in use today powering old-time free flight, CL, and RC aircraft. SAM (Society of Antique Modelers) regularly holds events for Ohlsson-powered airplanes.

A big reason these engines have survived is the ample supply of newly made spare parts that my late friend Vic Didelot arranged to have manufactured. Following Vic’s death, his Ohlsson parts supply was taken over by Burnis Ray:

  • Burnis Ray
  • 6027 Ken Caryl Pl., Littleton CO 80128
  • E-mail: BurnisR@aol.com

I’ve also been told that George Tallent in Picacho, Arizona, can remove and replace Ohlsson cylinders. His telephone number is (602) 466-7655.

MA

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