About the rarity of the NPJ collection
The Golden Age of Aviation (1926 thru 1947) has sometimes
been called the “Forgotten Years” of aviation.
This is the only time in history that the restoration
and completion of a propeller collection from this era
and to this extent and rarity has even been achieved.
A collection like this does not exist anywhere else and
will never exist like this.
Of the 112 propellers that
comprise the entire collection, twenty-six are rare,
one of a
kind and New
old Stock (NOS) propellers. These propellers are like
finding a time capsule of this period of aviation.
The Smithsonian national Air and Space Museum (NASM)
has commented on the quality, condition and rarity of
the NPJ collection.
The following narrative describes a brief background
of some of the various rare propellers included in the
ERCO Compreg propellers, (total of 6 in the collection),
represent the complete manufacturing line of the retrofit
propeller blades for the Hamilton Standard hub. Also
one Fixed pitch propeller form the early 1930’s.
• Three types of plastic impregnated and compressed
hardwood propeller blades were produced for us with Hamilton
Standard propeller hubs. These blades were designed in
the early 1940’s to retro-fit the metal blade of
the Hamilton Standard Counter weight propellers as the
alternative for the shortage of aluminum during war time.
There were 2 designs of blades produced, 45” and
49” “B” shank in which 16,000 blades
were built for the 2B20's Hamilton Standard hub. The
primary use for this blade configuration was general
military trainer and small transport planes. There are
two 2B20 propellers with two blade designs in the collection.
• The 3rd blade design in which only 600 blades
were made for the “D” shank Hamilton Standard
2D30, 12D40 and 3D40 hubs. This “D” shank
blade was used primarily on the Vultee BT-13 trainer
and a few of the AT-6’s. Shortly after WWII the
BT-13’were aircraft disposed of as surplus property
and gifted to foreign countries. Along with the airplanes,
the Compreg propellers disappeared. Numerous inquiries
have been received from people in various European and
South American countries about what aircraft this blade
may have been used on.
• One of three wooden fixed pitch manufactured
in 1930 as a prototype with the scimitar blade design
with a SAE 20 spline hub.
• One of the first Freedman Burnham propellers
from Detroit, MI with a S/N in the low 30s.
• One of the early pre-patent Freedman Burnham
props built in Cincinnati, OH at their new location.
The propeller blades were constructed of the finest select
grades of birch and imported African mahogany. These
propellers were optional equipment and recognized for
their beauty and design.
Hamilton Aero Propellers:
• This ground adjustable propeller was designed for the Warner Scarab 110
hp, for the optional use on the 1928 Stinson Jr., which in 1928 there was reports
to be approximately 27 production aircraft manufactured and scattered around
the United States.
Standard Steel Propeller Corporation in Pittsburgh,
PA, Duraluminum propeller:
• This is one of two propellers made specifically
for the Curtiss RC-3R Racer in the 1926 Schneider Cup
race. This is a left rotation propeller set up for the
geared Packard engine. The engine had plenty of horsepower
but made it difficult to handle and maneuver the turns.
Since the introduction of the Freedman Burnham
adjustable-pitch propeller at the Chicago Air Show in 1937, two propellers
received type test approval from the Civil Aeronautics
Administration; the Roby controllable pitch propeller and the EVEREL
Automatic variable pitch propeller.
In comparative tests Beech controllable propellers showed
an increase in rate of climb and decrease of take-off
run from 15% to 26% for the various types of airplanes
on which it was tested. These propellers were made during
the war for the Army Air Force and were used on the various
fighting fronts and in the United States for small military
“ROBY” and Beech Roby Propellers:
• Actual and Original R-1, ROBY “prototype” Designed
by Walter Burnham and H.Roby in the late 30’s early
1940s, this specific propeller is shown with a pair of
Birch blades designed by Freedman Burnham and was autographed
on 1-23-1942. Patent was given in April 1942.
• R-100 Beech Roby propellers with blade serial
number 1,2 and 3,4. Each with prop hubs that were not
serial numbered for production.
An NOS R003 propeller for a Swift GC-1A.
• The original R002 used on Ernest Kowalisky’s
Army L-4J during WWII. This aircraft was an artillery
spotter for the 5th Army 88th Division Artillery Head
Quarters Battalion as a spotter aircraft.
In 1945 Hartzell developed the world’s first composite
propeller blade using a fabric-based plastic material
(Panelyte), which was dubbed Hartzite. Hartzite is weather
proof through and through, minor damages were not serious.
Hartzite, a proprietary composite material, had the highest
fatigue strength-weight ratio and the highest vibration-damping
qualities of any propeller developed in this time.
• Hartzell wood 3-blade HC-93ZF-28, 102” diameter
and is the only one of this type known to exist. It was
1 of 2 made for the VZ-6 VTOL>
Hoover Hydraulic Propeller
The Hoover Hydraulic was manufactured by Canadian Car
and Foundry and the blades were manufactured by Singer
Manufacturing in Winnipeg, MB using the ERCO manufacturing
process. The museum in Hamilton, Ontario is home of one
of the only restored Fleet 60 Fort aircraft and the propeller
shown on the display aircraft is incomplete due to a
• There are two of the Hoover Hydraulic propellers
in the collection. These propellers were designed for
the Fleet 60 Fort trainer with only 101 of these aircraft
built. Hoover also built the prop used on the Anson Mark-V.
First advertised as the “Propeller with a Brain
for Tomorrow’s Plane”, the Aeromatic Air
Controlled Automatic Propeller was licensed under patents
of EVEREL Propeller Corporation, KOPPERS Col, Inc. Bartlett
Hayward Division, Baltimore, MD.
EVEREL Propeller Corporation in Baltimore, Maryland
Walter E. Everets was the designed of the EVEREL Single
Blade propeller. During the testing and experimental
stages, Everets found that the single blade produced
25% greater thrust than the conventional two-blade propeller.
Nearly sixty experimental full-sized blades and more
than a dozen hubs and mechanisms were built and tested
before the 40-horsepower model of the single blade was
submitted for an Approved Type Certificate, which was
received for the Taylor A and the J-2 Cub.
Koppers Company Inc. Barlett Haward Division, Baltimore,
This ground adjustable Aeromaster propeller was manufactured
in the early 1940s and was type certificated for a Republic
Aeromatic, Koppers, Bartlett Hayward/ EVEREL
• This propeller was used on the First Navy Interstate
TDR-3 Unmanned Radio remote controlled bomber.
• Also included is the Aeromatic F-200 with proto-type
aluminum skin, wood blades.
There were a number of propellers manufactured and licensed
by the Everel Propeller Corporation in Baltimore, Maryland.
This company was subsequently bought out by Univair Corporation
and the manufacturing rights are now owned by Kent Tarver,
The NPJ collection represents one model of each of their
subsidiaries, EVEREL, Aeromaster Koppers Bartlett Hayward,
Aeromatic Koppers Bartlett Hayward, Aeromatic Koppers
Universal, Aeromatic Univar, and Aeromatic Tarver propellers.
Propellers acquired from the Continental factory in
Muskegon, Michigan are:
• NOS S/N 1 of the Continental Sky Power
acquired from the Continental Aviation factory in Muskegon,
Michigan. First advertised as “the Continental “Aviation
Skypower” propeller specially designed for the
greatest efficiency and performance. It’s simple
in design and operation, low in price and easy to install
• A Hartzell test club for the Continental 65
hp engine, also acquired from the Continental engine
Maynard DiCesare was manufactured in Milwaukee, WI
• This propeller is 77” in diameter and
was first introduced at the New York National Aviation
Show in 1937. It was claimed that the unique arc of the
blades acts to bring the point of fatigue four inches
closer to the hub, and that the offset blade arrangement
provides better balance and reduced vibration to the
engine. According to the NASM, this propeller is 1
of 3 known of in existence.
Annesley 84” Diameter, the only information is
the hub patent in 1945, the NASM is looking for
Westinghouse Electric & Manufacturing Company, East
• The Micarta is a 102” diameter propeller
built for the Curtiss OX5 engine. The Tri-Motor, Army
Fokker C2-A and the Aristicat 102-E used this type of
propeller. The Micarta propeller was also used on the
first flights from San Francisco to Hawaii.
The above only briefly describes the twenty-six “one
of a kind” propellers that are part of the larger
collection. This collection consists of a complete representation
of the propeller manufacturer’s transition from
metal propellers back to wooden propellers during wartime.
In the late 1920s and 1920s aluminum had been perfected
for use for propellers blades. This collection represents
a short lived era of wooden propeller blades (1937-1946)
when, due to the aluminum shortages, the industry reverted
back to designing the propeller blades with wood and
using steel hubs for general aviation and small military
training aircraft. The collection represents unique and
rare examples from aviation history when the propeller
manufacturers developed the adjustable and controllable
hub along with the performance changes this made to the