Jetrader - Autumn 2016 - 58

aviation history

Double-Deckers and Portholes for

Pan Am's Juan Trippe
By Jack Feir

A Pan American Sikorsky S-42 cruising over the under-construction San Francisco-Oakland
Bay Bridge in 1935. Photo: Tom Wigley collection.

Times Were Changing
In the late 1930s, most of Pan American
Airways' destinations in the Pacific,
Atlantic and South America had been in
places with lagoons, harbors or rivers where
the flying boats could land and take off.
Especially in the Caribbean and South
America, much of the terrain near destination cities was mountainous, and Pan
Am simply lacked the resources to carve
out runways and build terminal facilities,
so it was most economical to serve those
destinations with large flying boats like
the Sikorsky S-42 and S-43, Martin M-130
and the Boeing 314.
But by the mid-1940s, as World War II
was winding down, Pan Am's fleet of large
flying boats (or at least what was left of the
fleet) was obsolete. Most of the destinations now had paved runways that had been
constructed to accommodate the DC-3s and

DC-4s that were doing so much of the heavy
airlifting in the war effort, so the era of
flying boats was over.
To prepare for the new peace-time
world of runways on solid ground, Pan
Am's president, Juan Trippe, placed orders
for two new types of aircraft. Both would
be "launch orders," ensuring that Pan Am
would get their aircraft before anyone else.
These were the Republic Rainbow and the
Consolidated Vultee (later Convair) CV-37.

The New Candidate Airplanes
The Rainbow was originally designed as
a high-speed, long-range photo reconnaissance aircraft, designated as the XF-12. It
was designed late in the war, with the prototype making its first flight in February 1946.
It demonstrated a speed of 470 mph and
could operate as high as 45,000 feet, and
very few interceptor aircraft could catch it.

58 The official publication of the International Society of Transport Aircraft Trading

Inside the Rainbow's spacious, pressurized
cabin was a manned "full-service" photo lab
so that reconnaissance film could be developed and printed in flight, ready to be examined immediately upon landing. That large
cabin space also meant that it could be fitted
out and offered as a 46-seat civilian airliner.
The Rainbow might be viewed as the Concorde
of its day: not large, but with speed and
altitude capabilities beyond anything else
available. Both Pan Am and American Airlines
placed orders for Rainbows, expecting to use
them on transcontinental and trans-Atlantic
routes, where most of the existing aircraft
were slow and unpressurized.
In comparison to the Rainbow, the Convair
CV-37 would be a double-deck monster, powered by six pusher-propeller engines and
capable of carrying more than 200 passengers over 3,000 miles non-stop. It would
be the largest passenger airliner ever built,
with spacious lounges and separate men's
and women's dressing rooms on both levels.
Like the Rainbow, the CV-37 was a derivative of a military aircraft; in this case the origin was the Convair B-36 long-range bomber,
from which the first derivative prototype was
the XC-99 military freighter aircraft with a
fuselage longer and wider than the B-36 and
enough space to carry 400 fully equipped
troops. The CV-37s that Pan Am ordered were
to be civilian versions of the XC-99.
In the end, neither the Rainbow nor the
CV-37 went into production. Without the
benefit of a military orders, Convair could
not justify the Rainbow airliner development with only the few orders in hand from
Pan Am and American. As for the CV-37, Pan
Am also determined that it would have had
unacceptable fuel consumption, so it would
have been too costly to operate and would
not meet the desired range capability.
With the double-deck CV-37 out of the
running, Pam Am's long-haul fallback was
the Boeing 377 Stratocruiser, derived from

Jetrader - Autumn 2016

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