Sadler Radial Engines Inc, of Coupeville, WA. (now Constant Pressure Engines Inc). Initially run by William Sadler, apart from building ultralight aircraft, he created this company that took Alex Pong's Dragon to market, and later he created a larger engine known as R-1745U, larger than the original Dragon.

“Sadler, R-1745U”

-It has many VW parts, such as pistons. It has six radial cylinders in two rows of three, coupled with the cylinders interspersed.

-The crankshaft has two crank pins at 180°.

-It delivered 45 HP at 2,450 rpm, and it gave way to another slightly larger model, the R-1765U.

“Sadler R-1765U”

-This air-cooled engine was very similar, with six radial cylinders, carburetor, and double electronic ignition.

-It gave 65 HP at 3,000 rpm weighing 108 pounds dry.

-Due to economic difficulties, this company has been for sale for some time. In their projects there was an 85 HP and a 110 HP engine.