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- Mark-11 -

Offset, HyVo Propeller Reduction Unit (discontinued)

The Mark-11 PSRU was designed to provide a high-reliability, modest-cost chain-drive PSRU, which had the offset and torque capacity features which make it attractive to replica-fighter builders who want to use a GM or Ford V8 engine. We decided against producing it because of the inherent superiority of our geared reductions, and because of a very limited market for this product.

The following text describes the capabilities of the design.

The Mark-11 had two different input torque capacities: 550 lb-ft. and 700 lb-ft., and was designed for the Smallblock or Bigblock Chevrolet engine as well as the 460-Ford engine configurations. Power transmission was implemented with a Hy-Vo™ chain, which allowed the use of an engine which rotates in the same direction as the propeller.

The Mark-11 had a vertical distance between the crankshaft and propshaft centerlines of 8.0 inches, and provided a wide selection of reduction ratios in the same package. It contained the proven reliable technology (component design, load-bearing, lubrication, cooling and vibration) as the Mark-9, and had the simplification and maintenance improvements developed in the Mark-10.

The specifications were:

  1. Minimum weight was approximately 78 pounds;
  2. There was a medium and high input torque version: 550 and 700 lb-ft.; both had a thrust capacity of 3000 lbs;
  3. It had an integrated, gear-driven governor pad (AND-20010) with internal control plumbing, designed to accommodate a standard Woodward or Hartzell single-acting prop governor.
  4. It included provision for a reversing prop and the beta-feedback mechanism for reversing control;
  5. It provided reduction ratios ranging from approximately 1.85 to 2.55;
  6. It was designed to withstand the very high gyroscopic loads imposed by the propeller during sudden maneuvers, gusts, or aerobatics.
  7. It was designed to provide either of two high-capacity prop-flange configurations:
    --- ARP-880, the 8-bolt, 2-dowel configuration used on the PT-6 and TPE-331 turbine engines, and most GTSIO-520 engines;
    --- ARP-502, the 6-bolt, 2-dowel configuration used on some Lycoming and Continental engines, including certain GTSIO-520 models.
No prototype was built, and we do not intend to build any because of the inherent superiority of our geared reductions drives.
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