Blériot XI

https://en.wikipedia.org/wiki/Bl%C3%A9riot_XI

The Blériot XI is a French aircraft of the pioneer era of aviation. The first
example was used by Louis Blériot to make the first flight across the English
Channel in a heavier-than-air aircraft, on 25 July 1909. This is one of the most
famous accomplishments of the pioneer era of aviation, and not only won Blériot
a lasting place in history but also assured the future of his aircraft
manufacturing business. The event caused a major reappraisal of the importance
of aviation; the English newspaper The Daily Express led its story of the flight
with the headline "Britain is no longer an Island".

It was produced in both single- and two-seat versions, powered by several
different engines, and was widely used for competition and training purposes.
Military versions were bought by many countries, continuing in service until
after the outbreak of World War I in 1914. Two restored examples – one in the
United Kingdom and one in the United States — of original Blériot XI aircraft
are thought to be the two oldest flyable aircraft in the world.

Design

The Blériot XI, largely designed by Raymond Saulnier, was a development of the
Blériot VIII, which Blériot had flown successfully in 1908. Like its
predecessor, it was a tractor-configuration monoplane with a partially covered
box-girder fuselage built from ash with wire cross bracing. The principal
difference was the use of wing warping for lateral control. The tail surfaces
consisted of a small balanced all-moving rudder mounted on the rearmost vertical
member of the fuselage and a horizontal tailplane mounted under the lower
longerons. This had elevator surfaces making up the outermost part of the fixed
horizontal surface; these "tip elevators" were linked by a torque tube running
through the inner section. The bracing and warping wires were attached to a
dorsal, five-component "house-roof" shaped cabane consisting of a pair of
inverted V struts with their apices connected by a longitudinal tube, and an
inverted four-sided pyramidal ventral cabane, also of steel tubing, below. When
first built it had a wingspan of 7 m (23 ft) and a small teardrop-shaped fin
mounted on the cabane, which was later removed.

Like its predecessor, it had the engine mounted directly in front of the leading
edge of the wing and the main undercarriage was also like that of the Type VIII,
with the wheels mounted in castering trailing arms which could slide up and down
steel tubes, the movement being sprung by bungee cords. This simple and
ingenious design allowed crosswind landings with less risk of damage. A sprung
tailwheel was fitted to the rear fuselage in front of the tailplane, with a
similar castering arrangement.

When shown at the Paris Aero Salon in December 1908, the aircraft was powered by
a 26 kW (35 hp) 7-cylinder R.E.P. engine driving a four-bladed paddle-type
propeller. The aircraft was first flown at Issy-les-Moulineaux on 23 January
1909, but although the aircraft handled well, the engine proved extremely
unreliable and, at the suggestion of his mechanic Ferdinand Collin, Blériot made
contact with Alessandro Anzani, a famous motorcycle racer whose successes were
due to the engines that he made, and who had recently entered the field of
aero-engine manufacture. On 27 May 1909, a 19 kW (25 hp) Anzani 3-cylinder
fan-configuration (semi-radial) engine was fitted. The propeller was also
replaced with a Chauvière Intégrale two-bladed scimitar propeller made from
laminated walnut wood. This propeller design was a major advance in French
aircraft technology and was the first European propeller to rival the efficiency
of the propellers used by the Wright Brothers.


Role
Civil tourer/trainer/military

Manufacturer
Louis Blériot

Designer
Louis Blériot and Raymond Saulnier

First flight
23 January 1909


The Channel crossing

The Blériot XI gained lasting fame on 25 July 1909, when Blériot crossed the
English Channel from Calais to Dover, winning a £1,000 (equivalent to £115,000
in 2018) prize awarded by the Daily Mail. For several days, high winds had
grounded Blériot and his rivals: Hubert Latham, who flew an Antoinette
monoplane, and Count de Lambert, who brought two Wright biplanes. On 25 July,
when the wind had dropped in the morning and the skies had cleared, Blériot took
off at sunrise. Flying without the aid of a compass, he deviated to the east of
his intended course, but, nonetheless, spotted the English coast to his left.
Battling turbulent wind conditions, Blériot made a heavy "pancake" landing,
nearly collapsing the undercarriage and shattering one blade of the propeller,
but he was unhurt. The flight had taken 36.5 minutes and had made Blériot a
celebrity, instantly resulting in many orders for copies of his aircraft.

The aircraft, which never flew again, was hurriedly repaired and put on display
at Selfridges department store in London. It was later displayed outside the
offices of the French newspaper Le Matin and eventually bought by the Musee des
Arts et Metiers in Paris.

Subsequent history

After the successful crossing of the English Channel, there was a great demand
for Blériot XIs. By the end of September 1909, orders had been received for 103
aircraft. After an accident at an aviation meeting in Istanbul in December 1909,
Blériot gave up competition flying, and the company's entries for competitions
were flown by other pilots, including Alfred Leblanc, who had managed the
logistics of the cross-channel flight, and subsequently bought the first
production Type XI, going on to become one of the chief instructors at the
flying schools established by Blériot.

In February 1912 the future of the Type XI was threatened by the French army
placing a ban on the use of all monoplanes. This was the result of a series of
accidents in which Blériot aircraft had suffered wing failure in flight. The
first of these incidents had occurred on 4 January 1910, killing Léon
Delagrange, and was generally attributed to the fact that Delagrange had fitted
an over-powerful engine, so overstressing the airframe. A similar accident had
killed Peruvian pilot Jorge Chavez at the end of 1910 at the end of the first
flight over the Alps, and in response to this the wing spars of the Blériot had
been strengthened. A later accident prompted further strengthening of the spars.
Blériot produced a report for the French government which came to the conclusion
that the problem was not the strength of the wing spars but a failure to take
into account the amount of downward force to which aircraft wings could be
subjected, and that the problem could be solved by increasing the strength of
the upper bracing wires. This analysis was accepted, and Blériot's prompt and
thorough response to the problem enhanced rather than damaged his reputation.

Specifications (Blériot XI)

General characteristics
Crew: 1
Length: 7.62 m (25 ft 0 in)
Wingspan: 7.79 m (25 ft 7 in)
Height: 2.69 m (8 ft 10 in)
Wing area: 14 m2 (150 sq ft)
Empty weight: 230 kg (507 lb)
Powerplant: 1 × Anzani 3-cyl. fan 3-cyl. air-cooled fan-style radial piston
engine, 19 kW (25 hp)
Propellers: 2-bladed Chauvière Intégrale, 2.08 m (6 ft 10 in) diameter

Performance
Maximum speed: 75.6 km/h (47.0 mph, 40.8 kn)
Service ceiling: 1,000 m (3,300 ft)




*