Hamilton Standard Propeller, Variable-Pitch, Four-Blade, Metal


Display Status:

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.

Collection Item Summary:

The stock market crash of 1929 and the Great Depression threatened continued existence of the American aviation industry as it had started to grow. The newly-formed Hamilton Standard Propeller Corporation, suffering from dwindling government contracts, scrambled for a new product to sustain the young corporation. Chief engineer Frank Caldwell's design for a hydraulic two-position, controllable-pitch, or hydro-controllable, propeller that patented in 1929 saved the company.

The hydromatic propeller introduced in the 1930s was a significant advance over the counterweight, controllable pitch propeller. Application of oil pressure to both sides of the actuating piston provided increased capacity and the capability of feathering or unfeathering by a single control knob. Reverse pitch permitted shortened landing roll.

In 1933 Hamilton Standard and Frank Caldwell won the prestigious Collier Trophy for development of the company's controllable pitch propeller.

This propeller was used on the Martin P5M twin-engine flying boat of the 1950s and 60s.

Collection Item Long Description:

Data Source

National Air and Space Museum



Steel, Aluminum alloy, Paint, Rubber, Adhesive


  • Approximate: 78.74 x 459.74 x 459.74cm (2ft 7in. x 15ft 1in. x 15ft 1in.)
  • 181in. diameter, 13-1/4in wide
  • Diameter: 181 in.
  • Chord: 13.25 in.

Country of Origin

United States of America

Physical Description

  • Type: Four-Blade, Variable-Pitch, Metal
  • Diameter: 460 cm (181 in.)
  • Chord: 33.66 cm (13.25 in.)
  • Engine Application: Wright R-3350


PROPULSION-Propellers & Impellers

Inventory Number


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