Sadler radial aircraft engine.

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Sadler radial aircraft engine.

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By Don Downie

COUPEVILLE, Washington - Wanted: a good home for the Sadler radial engine. This unique 65-hp, six-cylinder radial is in the market for a change of leadership. Bill Gewald, who developed the engine from Sadler's design, has turned 75 and together with his wife Betty feels it is about time for younger, more energetic people to take charge.

Back in 1985, Bill Sadler and Bill Gewald began searching for a reliable four-stroke engine for ultralights and homebuilts. Sadler had developed the Sadler Vampire, a twin-tailed ultralight that was eventually produced for government reconnaissance drones and modified as a ground support fighter. He went on to design Formula 1 race cars and was an instructor at Massachusetts Institute of Technology.

Sadler teamed with the Gewalds to form the engine development company. Prior to that, the Gewalds operated two oil exploration air charter companies in Southeast Asia-one in North Borneo and the other in Singapore.

Betty took flying lessons in Manila and Bill, a mechanical engineer, was taught to fly by his charter pilots in the company Cessnas, Lockheeds and C-47s.

Sadler and the Gewalds began a worldwide search for an existing reliable four-stroke engine and found nothing to their liking. So they decided to invent and build one on their own.

End result was the Sadler 6-cylinder radial engine with a four-cycle, dual electronic ignition with direct drive unit. Made with up-to-date materials and using modern computer numerically designed machinery, the engine has redundancy (12 spark plugs), low rpm, minimum vibration, low fuel consumption and low noise levels.

Patent No. 5,l50,670, was issued in 1992 and a total of 43 proof-of-concept engines were built, but none were offered for sale. According to Betty the company could not support the units with spare parts. However, the engine was installed in an Avid Model C where it produced a cruise speed of 85 mph, a 1,250 fpm rate of climb at gross weight, and a service ceiling above 12,500 feet. The engine, including electric starter and alternator, weighed 121.4 pounds and the all-up weight including engine mount, exhaust manifold and propeller was 162 lbs.

The engine package being offered to investors includes drawings, CAD programs, patterns, jigs and fixtures and many parts for the 65-hp R1765U engine. In addition, preliminary engineering and feasibility studies have been completed for 85-hp and 110-hp versions. Mrs. Gewald stated that only crankshafts and cylinder heads are needed to produce completed 65-hp engines.

"We have never been able to raise enough money to go into full production, but we have all the drawings on autocad. We also have over $17,000 worth of patterns for all the proprietary parts," she said. "It is a reliable, smooth, compact engine with low RPM (red-line is 3000 rpm) that runs beautifully on automotive fuel and sounds like a radial.

We want to sell to someone with the financial resources to treat the engine with the TLC it deserves. We will accept the bulk of any payment based on sales royalties and will personally help all we can in production and sales."

The company now has one engine running on a stand at the Arlington Airport north of Seattle that is available for demonstration the homebuilders with scaled-down replicas of the Golden Era of biplanes: Wacos, TravelAirs, Stearmans, Rearwins, and others originally produced with radial engines. The sound alone would bring pilots and bystanders alike out of the airport cafes and ready-rooms just to listen.

So, if there is someone or a group out there wanting the challenge of producing a well-researched, out-of-the-ordinary engine design with the time-consuming R&D and basic tooling already complete, contact the Gewalds at Sadler Radial Engines, Inc, 603 NE 9th St., PO Box 953, Coupeville, WA 98239-0953.

Sadler Radial Engine

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