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Quest for Performance: The Evolution
of Modern Aircraft
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- Part I: THE AGE OF
PROPELLERS
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- Chapter 3:The Lean Years,
1918-26
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- Transport Developments in
Europe
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- [68] In contrast to
the slow development of airline aviation in the United States,
European air transport began almost immediately after the
cessation of hostilities in 1918. The major capitals of Europe
were soon connected by primitive passenger-carrying airlines. The
aircraft types utilized for carrying passengers were at first
hastily converted [69] military bomber
and observation types. Later, new aircraft were constructed for
the infant airlines; however, these aircraft usually followed the
standard biplane formula developed during World War I. Typical of
these transport aircraft is the Handley Page trimotor shown in
figure 3.2. The aircraft was a multibay biplane, similar in
configuration to the bomber types of the war, but employed an
enclosed cabin capable of carrying 10 passengers. The two pilots
were accommodated in an open cockpit
just forward of the leading edge of
the upper wing, as can be seen in figure 3.2. Note the four-blade
propellers and the multiple wheels of the landing gear. The use of
the four-wheel gear was no doubt a concession to the relatively
soft sod or mud landing fields of the period. A glance at the
characteristics of the aircraft given in table II indicates a relatively heavy machine of 13
000-pound gross weight, but with only 840 horsepower as the
combined output of the three engines. The wing loading was a very
low 8.9 pounds per square foot in order that the aircraft could
operate out of the small fields that existed at the time. The
cruising speed was a modest 85 miles per hour; the drag
coefficient at zero lift was 0.0549, which was larger than that of
the DH-4. Although the use of multiple engines is usually thought
to increase safety and reliability, that was not the case with the
Handley....
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- [70] Figure 3.2 - Handley Page model W8F 12-passenger
trimotor transport; 1924. [Flt.
Intl.]
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- .... Page trimotor. The aircraft could not
maintain level flight following the loss of one engine according
to the information given in reference 75. The Handley Page trimotor was Put into operation
by the British Imperial Airways and the Belgium Sabena Airways
Systems in about 1924 and continued in operation, at least to some
limited extent, until about 1931. In fact, very large multiengine
biplanes were utilized on some European airlines right up to the
beginning of World War II.
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- Aircraft employing the monoplane
configuration had been built since the early days of aviation. The
first nonstop flight across the English Channel was made in 1909
by Bleriot flying a wire-braced monoplane, and many early World
War I fighters were also monoplanes (chapter 2). Most early monoplanes employed a multitude of
wires and struts in order to provide strength and rigidity to the
wings. As a consequence, the drag characteristics of these
aircraft showed little if any improvement compared with
contemporary biplane drag characteristics. Furthermore, there
seemed to be a lack of confidence in the structural integrity of
the monoplane configuration. There were also experiments with
internally braced, cantilever monoplanes. As indicated in
chapter
2, the German designer Junkers
built cantilever monoplanes constructed of metal. The materials
and design methods available during World War 1, however, did not
lend themselves to the construction of light, all-metal cantilever
designs. Another early proponent of the cantilever
[71]
monoplane was the Dutch designer Anthony H. G. Fokker. Fokker
designed and built fighter aircraft for the German Air Force
during World War I. His first cantilever monoplane fighter was the
model D-VIII, which featured an internally braced wing mounted on
struts above the fuselage. (See figure 2.16.)
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- In 1920 and 1921, Fokker developed a
single-engine transport employing an internally braced wing
similar in concept to that of the DVIII fighter. This aircraft,
known as the Fokker F-2, is depicted in figure 3.3. The aircraft
seated three or four passengers in an enclosed cabin, and a single
pilot was located in an open cockpit Just under the leading edge
of the wing. The absence of external struts and wires to support
the wing is obvious from the photograph. The relative aerodynamic
cleanliness of the design would be expected to produce a
correspondingly low value of the zero-lift drag coefficient. The
data in table
II, however, suggest that the value
Of CD,O is not much better for the Fokker than for the
DH-4. The open cockpit together with a poor engine installation
and consequent high cooling drag suggest themselves as possible
reasons for the relatively high zero-lift drag coefficient. The
wooden cantilever wing and steel-tube, fabric-covered fuselage
formed the basis for a long line of Fokker aircraft built right up
to World War II. An improved and larger version of the Fokker F-2,
known as the T-2, was the first aircraft to fly nonstop across the
United...
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- [72] Figure 3.3 - Fokker F-2 four-passenger transport;
1920. [Flt. Intl.]
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- .....States. This flight was made by the
U.S. Army Air Service in 1923 (ref. 38). The famous Fokker trimotor was very similar in
configuration to the F-2 but employed three modern engines, had a
fully enclosed cabin and cockpit, and was much larger than the
F-2. The first of the Fokker trimotors was employed by Richard E.
Byrd and Floyd Bennett in their historic first flight over the
North Pole in 1926.
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