HISTORIC AIRPLANES: de Havilland
Workhorse of the Postal Service
In 1918 the Post Office Department requested
100 de Havilland airplanes, model DH-4, from the army. Designed
by British engineer Geoffrey de Havilland, these airplanes
had been built both in England and the United States during
the last years of the war. Like most of the 2,500 fighter
airplanes built in the United States by 1918, few DH-4 aircraft
even saw battle.
Although the airplanes' range (350 miles)
and load capacity (500 pounds) were good, de Havillands
were not suited for the rigors and demands of airmail service,
having been built for high-altitude military observation
use. The most precarious design flaw was the placement of
the cockpit. Pilots were too easily trapped between the
engine and the mail compartment in accidents where minor
crashes turned deadly, burning entangled pilots alive. The
airplanes quickly gained a macabre nickname—flaming coffins.
Among those killed in the early de Havilland airmail flights
was Carl Smith, who stalled out over Elizabeth, New Jersey,
while testing a DH-4 on December 16, 1918.
In January 1919, the de Havillands were removed
from service for extensive renovation work. The cockpit
was moved to the rear and rimmed with padded leather for
cushion in rough landings. The exhaust stacks were extended
beyond the cockpit, so pilots would no longer be blinded
by exhaust fumes. To make the airplanes more durable, the linen
fabric fuselage was replaced with plywood sheets over wood
struts. The landing gear was repositioned and larger wheels
were installed. The DH-4 instrument panel also had problems.
The airplane's compass was notoriously unreliable.
When flying east, it could oscillate from east to 90-degrees
north. Air pressure through a metal pipe activated the airplane's
air speed indicators. Unfortunately, the pipes, placed on
the bottom wing's leading edge, were regularly filled with
mud. More seriously, the altimeter registered 1,000 feet
for each 1" around the scale, making it useless below
the retrofitted de Havillands (now known as DH-4B) were returned
to service, the improvements proved enormously successful.
In their first year of service, de Havilland airmail airplanes
carried more than 775 million letters. The airplane quickly became
the workhorse of the airmail service. In 1921, as an additional
safety measure, pilots were assigned individual airplanes and
allowed to modify them to meet their individual demands. The
DH-4Bs began to retire from airmail service in 1926 when the
Post Office Department began to contract with private carriers.
When the Post Office Department relinquished control of the
airmail service to private industry, entrepreneurs used the
money they made from carrying the mail to maintain and expand
their routes and upgrade their services.
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Havilland Workhorse of the Postal Service.