The Curtiss C-46 Commando
By
Scott Schwartz
Billed by Curtiss
as the “Sub-Stratosphere Transport”, the airplane that became the C-46 military
transport was actually intended to be a 36 passenger airliner with a
pressurized cabin. It was an attempt to
compete with that other famous airliner of the 1930’s - the Douglas DC-3.
Called the
“CW-20T” by Curtiss, the prototype first flew in March of 1940. The CW-20T had twin vertical stabilizers and
was powered by two Wright R-2600 14 cylinder engines producing 1,600 horsepower
each, and turned three blade Hamilton-Standard constant speed propellers.
After initial
flight testing, the twin tail arrangement was replaced by a single vertical
stabilizer, and testing revealed that the CW-20 had some promise as an
airliner. Whether it would have posed a
threat to the DC-3’s market share is debatable.
On paper, the CW-20 seemed much more capable than the DC-3, with greater
fuel capacity, more seats, and a higher service ceiling. However the CW-20’s larger engines used more
fuel, which limited the aircraft’s range.
All of this, however, is academic, as the U.S. was gearing up for war.
September, 1940
saw the U.S. Army order 200 CW-20B’s, which were designated as C-46’s. The first 25 C-46’s were basically civilian
aircraft that were slightly modified for military use. The 26th aircraft to come off the
production line was the first C-46 “A” version, which in turn was the first
true military version of the aircraft.
It was powered by the Pratt &Whitney R-2800 engine, producing 2,000
horsepower. Ironically, this was the
engine originally intended for the airplane. Other changes included:
replacement of the Hamilton-Standard propellers with four blade Curtiss
Electrics, no cabin pressurization (although the airplane retained its service
ceiling of 22,000 feet – no doubt due to the two stage supercharger equipped
engines – a vestige of the airplane’s pressurized airliner roots), a reinforced cargo floor, and extra large
cargo doors on the fuselage. Although 17 different variants of the airplane
were produced, the C-46A and C-46F made up the bulk of the production run. A total of 3140 Commandos were made before
production ended in 1946.
Initially, the
C-46 was used to ferry cargo across the South Atlantic .
It also saw some use as a glider tug in the European theatre. However, the C-46 became famous for its use
in the China-Burma-India (CBI) Theater, flying supplies over Himalaya
Mountains , otherwise known as “the Hump”.
By March of 1942, the Japanese had control of nearly all of
the supply routes through the area. Consequently
all of the supplies needed by Chiang
Kai-Shek and Claire Chennault (who in June of that year became General Chennault when his American
Volunteer Group was absorbed into the U.S. Army Air Forces), including aviation
gasoline had to be flown in to China. Some
of the terrain in the area rises to over 14,000 feet. The route was initially flown by C-47’s that
were equipped with two stage superchargers, and C-87’s, which were cargo versions
of the B-24.
The C-87 retained
the long range and high altitude operating capability of its B-24 cousin. It also retained the B-24’s basic fuselage,
the interior of which was 33 feet long, 4 feet wide and 8 feet high. While the C-87 could lift heavier loads than
the C-46 and featured more “head room”, the narrow bomber-type fuselage made it
difficult to carry large cargo items, even with the addition of a cargo door.
Perhaps the most famous cargo aircraft of World War II, the
C-47’s cargo area was wider than the C-87’s, but its maximum loaded weight was
only 26,000 pounds.
On the other hand, the cargo area in the C-46 was 48 feet
long, 9 feet, 10 inches wide, and 6
feet, 8 inches high. Its maximum loaded
weight was 45,000 pounds (which could be pushed to 50,000 pounds).
Not surprisingly, the C-46 became the mainstay of the CBI
cargo route because of its combination of range, payload, and high altitude
capability.
Even with a capable cargo airplane such as the C-46, the
Hump route was fraught with danger. There were enemy planes to contend with, (legend
has it that a C-46 crew member shot a Zero down by firing his rifle though an
open cockpit window.), the departure airfields in India were hot and humid, and
the monsoon season was a killer.
Literally. The demand for supplies was so great, that pilots were
expected to fly under conditions that would normally ground airplanes based
elsewhere. Accidents were common. Water
leaked into cockpits through gaps in the window panes. In addition, navigation
aids were scarce, and the airplanes were forced to operate near their limits. Even in an airplane such as the C-46, which
was designed to fly at high altitudes, high altitude flying was a strain on
engines, equipment and aircrews. Superchargers and/or engines failed on
occasion, equipment malfunctioned, and keeping a non-pressurized cockpit heated
was a challenge. The four hour flight
under such dangerous conditions exhausted pilots and aircrew.
Not to mention the fact that the airplanes were often
overloaded. If all of the foregoing
wasn’t bad enough, consider the fact that the C-46’s Curtiss Electric
propellers had a nasty tendency to suddenly shift into flat pitch by
themselves. This was due, in part, to
humidity corroding the wiring associated with the propellers.
Despite the hazards and losses, the C-46 had flown hundreds
of tons of cargo by the time operations ended in November of 1945.
Given its utility during the war, it should come as no
surprise that the C-46 was used quite extensively afterward. Small cargo operators scooped up surplus
Commandos and used them to ply the non-scheduled routes. Plus, the airplane was perfect for operation
in the rough terrain found in parts of South America, such as the Amazon jungle
and the Andes Mountains
The C-46’s military career didn’t end with World War
Two. The United
States used the C-46 (along with some other World War Two
types) to fly missions during the Korean War and the CIA used it during the Bay of Pigs invasion.
Still, age and wear have taken their toll, and there are
only around a dozen Commandos still flying today. Two
of them are operated by the Commemorative Air Force.
Performance (source: Janes American Fighting Aircraft of the
20th Century):
Maximum speed: 265
mph.
Cruising speed (@10,000 ft.): 227 mph.
Engines: 2 Pratt
& Whitney R-2800 18 cylinder engines producing 2000 hp.
Service ceiling: 24,500 feet.
Crew: Pilot,
co-pilot, navigator, and radio operator.
Readers should note that most preserved examples of
warplanes are not operated at the altitudes and speeds flown during the type’s
military service. This is to keep fuel,
repair, and maintenance costs down.
