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Aeroproducts Propellers
The Aeroproducts Propeller
by Tom Fey
What eventually became the Aeroproducts Propeller Company
had its humble beginnings in 1935 as Engineering Projects, Inc. of Vandalia,
Ohio. It was founded by two brilliant engineers, Werner J. Blanchard, who spent
several years with the Curtiss Electric Propeller Company, and Charles. J. MacNeil. Engineering Projects was bought by General Motors in 1940
for a speculated $50,000 and re-named
the Aeroproducts Division of GM. The company delivered only 73 of their novel
“Unimatic” Aeroprop propellers in the month of December 1941, rising to 12,500
props in the month of February 1944. In synchrony with the piston/propeller age
itself, Werner Blanchard, only 48 years old, died in 1948 crash of his Navion,
and James MacNeil died in the early 1950s at the tender age of 35 from a heart
attack. Aeroproducts evolved to become a Division of Allison, then to Detroit
Diesel, to Hamilton-Standard, and ultimately the type certificate for its most
modern propeller now resides with Pacific Propeller.
The Aeroproducts “Unimatic” constant-speed propeller was an
ingenious, relatively light-weight unit that incorporated the governor, high
pressure oil pump, filter, pressure bypasss valve, and fluid supply in a
donut-shaped assembly on the back of the propeller hub. The only connections to
the airframe were the prop nut and a single steel linkage to control speed. The
Aeroprop could be changed in under 20 minutes, the hollow steel blades were
specifically indexed for hub socket number, and the blades were pre-weighed and
balanced such that one blade could be replaced without disturbing the others
thus no requirement for re-balancing or removal of the prop from the engine. If
the engine lost oil, the Aeroproducts propeller remained fully controllable due
to its independent hydraulic system. Each blade socket had its own hydraulic
actuating torque unit that fit into the hollow butt of the blade shank, and the
bore of the propeller hub was empty, allowing for a cannon barrel, pitot tube,
or radar mount to extend through the hub.
Aeroprops were used as original equipment on a multitude of
piston aircraft, including versions of the P-39 Airacobra, all the P-51K and
P-51H Mustangs, P-63 Kingcobras, P-82 Twin Mustangs, Grumman F8F Bearcats, Douglas AD Skyraiders,
North American T-28A Trojans, the Fairchild C-119, the one-off Lockheed Model 75
"Saturn" and some versions of the Model 18 twin Beechcraft. In more recent times, the homebuilt unlimited air racer
Tsunami used an Aeroprop, as do many of the R-3350 powered Sea Furys.
Aeroproducts manufactured experimental coaxial, contra-rotating units that were
used on the Fisher P-75A Eagle, Boeing XF8B-1, Curtiss XBTC-2, Republic XP-72,
North American A2J-2 Savage, the Convair Tradewind flying boat, and the Douglas A2D Skyshark.
As the turbo-prop era evolved in the late 1950s, the
Aeroproducts hollow-bladed propellers featured self-feathering, reverse pitch,
synchronizing/synchrophasing, and electric de-icing. These units were used on
the Allison T-56 turboshaft powered Lockheed L-188 Electra, Convair 580, Grumman
E2A Hawkeye, and Lockheed C-130A aircraft. The last Aeroproducts propeller unit
was delivered in 1974, and the final blade was plated in the Indianapolis Plant
5 on January 12, 1977, marking the end of Aeroproducts
propeller line.
Construction and Operation
Cutaways
  
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