Hello, and welcome to Aviation Deep Dive. The world of aviation in the 1940s and 1950s
was a fascinating place. Constant breakthroughs in technology, a better
understanding of aerodynamics and more powerful engines year by year meant that aircraft were
consistently getting faster, stronger, heavier armed, and… bigger. In the early 1930s the Tupolev ANT-20 was
the largest aircraft in the world, at just over 30 metres in length and 60 meters in
span. By 1940 the number of giant aircraft being
produced around the world had exploded, the Douglas XB-19, Me 232, and Martin Mars all
took to the skies within 1 year of each other. It was the golden age of aviation, and development
only progressed more rapidly with the outbreak of the Second World War. Today, however, our story takes us to France,
where a similar giant was in the process of construction. The Latecoere 631 was in every sense of the
word a flying behemoth, but to better understand its design we must head back to the mid-1930s. The transatlantic flight route was booming,
with such aircraft such as the Boeing 314 ferrying passengers in unparalleled luxury
and speediness from the US to Europe. It was an extremely profitable enterprise,
and so in 1936 the Directorate General for Civil Aviation in France issued a specification
for a 20-passenger flying boat airliner with a range of 6,000 kilometres. A quick message - if you want to skip to the
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you watching my stuff on YouTube anyway. Anyway, back to the video! The specifications were broad, but with a
promise of an order three companies ultimately began work on a design, these being Potez,
Lioré et Olivier, and Latécoère. With pen set to paper, the three all produced
a design, with some striking similarities. All were hexameteur, or six-engined designs,
and were of course extremely large, though the Latécoère was the largest. The Potez-CAMS 161 was the first competitor
to really take shape, followed closely by the Sud-Est SE.200 Amphitrite. Latécoère proposed their design in 1936,
as the 630. Intended to be powered by six Hispano-Suiza
12Y inline engines producing 930 horsepower each, the company laid out the plan for an
all-metal 44 ton aircraft, spanning 57 metres and and 35.9 metres in length. Work began on a small scale model to conduct
wind tunnel testing, but overall progress on the specification was taking longer than
the Air Ministry had expected, and with significant advancements in aviation technology since
the companies had begun, they decided to revamp the specification. Latécoère was instructed to stop working
on the Laté 630 design in July 1937, and instead requested that they modify the design
to meet new requirements. They now wanted an aircraft with double the
passenger capacity of 40, a cruising speed of 300 km/h and capable of carrying 5,000kg
of cargo. The range was not updated, and the Laté 630
was projected to have a range almost 2,000 km above the requirements anyway, so Latécoère
instead put their focus to enlarging the design, and increasing the speed. The old inline engines were ditched, to be
replaced by Gnôme Rhône 18P 1,500 hp engines - increasing the power output by 60%. Interestingly the Air Ministry was apparently
playing favourites by this point, as the other companies competing for the tender did not
get the updated memo, and so continued work on their older designs. Nevertheless, in October 1937 Latécoère
had finalised their new and updated version of the aircraft, imaginatively dubbed the
631, and a small scale model for wind tunnel testing was created. Testing revealed no real issues, and so the
order for the first full scale prototype was put through on the 1st July 1938, Latécoère
beginning construction at their plant in Toulouse, in the South of France. Construction would not be speedy however,
the plans laid out by the French company represented an aircraft to truly enormous proportions. 43 metres in length, 57 in span, and a whopping
10 metres tall - the 631 would be constructed out of 32,000 kg of aluminium, and would seat
46 passengers in relative luxury. At this point however, solid facts become
a little shaky for the SE.200, and flat-out unclear for the Potez 161. A contemporary report from the Flight magazine
says it was completed and undertook its maiden flight on the 7th December 1939, whilst another
gives 20th March 1942 as the date. Regardless, the 161 was the first competitor
for the specification to fly. Both the Latécoère 631 and the SE.200 were
still under construction and nowhere near ready flying tests when France fell to the
Germans on 22nd June 1940. In fact, it would be almost two full years
until either were ready. Construction of four SE.200s had been underway
since before the war had even began in South France, but progress was painfully slow, and
by the time the first was ready, it was immediately seized by the Germans and taken for testing. The 631, meanwhile, had began construction
as far back as 1938, but following the German invasion it had completely stopped, and Latécoères
facilities were apparently put to better use cranking out war machines. Following the Franco-German armistice, Latécoère
was temporarily banned from pursuing this project, though after the ban was lifted in
1941 the company finally began construction again, the aircraft being ready in mid-1942,
four years after the beginning of construction. The result of their efforts, though, was certainly
a machine worth admiring! Latécoère had been able to secure six Wright
R-2600 Cyclone engines, which at 1,600 horsepower each, gave a modest power increase over the
previous Gnome-Rhones. Standing at 10 metres tall, 43 metres in length,
and 57 metres in span, the Laté 631 was in fact the longest aircraft in the world - was
one of the heaviest, and was certainly an incredibly striking design. With the large angle of dihedral on the elevators,
twin vertical stabilisers, and of course its characteristic enormous nose - the cockpit
was set back very far on the aircraft, about 9 metres, which remains one of the 631s most
striking features. Shipped to Southern France in parts, the aircraft
would be finally assembled at Marignane, and underwent its first flight on the 4th November
1942. It’s hull lifting smoothly from the water,
the aircrafts handling proved to be steady and docile, and the aircraft logged around
fifty hours of flight. Construction of the second aircraft was also
underway. Unfortunately, the aircraft would be short-lived
in French hands, as the behemoth caught the eye of German officials, and under the instruction
of former Lufthansa pilot, Hans Werner Von Egel, the 631 was confiscated - painted in
German markings and flown to Lake Constance - on the German-Swiss border. There it would stay for the next few years. Unfortunately I can’t find any information
on German testing, it would have been interesting to see what they thought, but the 631 was
not the only confiscated aircraft to end up there - the SE.200 Amphitrite, competitor
to the same specification as the Laté 631, would also end up being taken by the Luftwaffe. The second prototype, now in fairly advanced
stages of production, was now in a strange situation. The workers at the factory apparently decided
that if they completed it it would simply be stolen by the Germans anyway, so they decided
to sabotage the project. However, destroying something as big as a
Parisian suburb was easier said than done, so they instead opted to disassemble all the
work, hide the parts and blow up the factory. This apparently was a success, although how
exactly they managed to ‘hide’ the parts of the 631 remains a mystery. Regardless, for the next year and a half no
progress was made. The captured 631 remained in German hands
whilst the second, partially constructed prototype stayed hidden from occupying eyes. In August 1944, the factory was liberated
by advancing allied forces, and so the various parts could finally be brought out from their
hiding places, the factory rebuilt and the aircraft begin final assembly. The parts were transported to Lake Biscarosse,
in Southern France, and after three long months the aircraft was finally completed. However, the so-called second’ prototype
would in fact be the only prototype by the time it was complete, as the first one - appropriated
by the Germans - had in fact been strafed where it was moored in April 1944, by two
RAF Mosquitos. In the attack the SE.200 Amphitrite would
also sadly be destroyed, an American raid would ultimately destroy the second amphitrite
too - which sealed the coffin of this project. Latécoère, however, was not so unlucky,
as with one aircraft they could still continue testing - which began on the 6th March 1945,
when the second prototype undertook its maiden flight. Having waited a good many years by this point,
the third prototype was quickly constructed whilst the second ironed out any flight issues. Air France was immediately interested, and
by July 1947 had placed an order for, and received four of the giants, to be used on
the transatlantic route to the French West Indies. The aircraft could finally stretch its wings,
and show its true potential. Cruising at speeds of 300 km/h (or 186 mph),
the 631 could complete a one way trip across the Atlantic in about 15 hours, then from
New York to the West Indies in another 5 and a half. With its colossal 6,000 km )or 3,750 mile)
range, the aircraft was perfectly suited for its passenger route - and it would carry its
46 passengers in luxury! Sporting a Lounge and Bar in the nose, the
aircraft had a series of private cabins along its length, where passengers could order food,
relax and enjoy the view. The aircraft would also have two decks, the
upper for the five man crew and the lower for the passengers. Over the next few years more aircraft would
be built and enter service on passenger routes, with three French airliners operating the
aircraft. Ultimately eleven would be completed (including
the first prototype), but the Latécoère was about to enter an era of its service life
which would essentially Marr its reputation and seal its fate. In October 1945, just three months after Air
France had begun serious operation of the type, one 631, on a route from Brazil to Uruguay,
suffered an engine failure, when the propellor from the No.3 engine ripped free from its
bearings and struck the No.2 engine, putting it also out of service. The enormous 5 metre (or 16 foot) propellor
also sliced a 3 metre gash into the side of the aircraft, killing two passengers who were
unlucky enough to be in the cabin which was struck. Though the 631 was able to succesfully land,
be repaired and was put back into service, this was unfortunately foreshadowing a string
of catastrophes that would plague the aircraft throughout its service life. Two and a half years later, on the 21st February
1948, the 631 would have its most fatal accident thus far. On a ferry flight to deliver the aircraft
from Northern to Southern France, the aircraft began to encounter issues over the channel. To make matters worse, the weather - which
had already been poor, began to take a turn for the worst, as a snowstorm began to rapidly
set in. Temperatures plummeted in the air as the crew
struggled to keep control of the enormous aircraft. The crew were stunned, the aircraft was losing
control in an all elements of flight - and though they battled bravely to keep control
of the stricken aircraft, it proved to be too much. A combination of the extreme weather, and
the dwindling control meant that the 631 began to lose its battle to the elements. All nineteen people on board were killed in
the crash, and a post-crash investigation revealed that the most probable cause was
ice accumulating on the control surfaces, jamming them, and eventually rendering them
inoperable. The 631 lacked any de-icing system, and as
eyes turned towards Latécoère over this utter disaster, faith in the design began
to decrease. Just six months later, mid-way through an
Atlantic crossing, another Air France 631 was lost - this time resulting in the death
of 52 people - all people on board. The cause of this particular crash was never
discovered, and only a couple of fragments of the destroyed aircraft were discovered
by search parties 6 days later. The official report concluded: “The members
of the committee are unanimous in attributing the accident to a serious and sudden event
whose origin could not be verified with certainty." This was an absolute disaster, the aircraft
had now killed over 73 people in the course of less than 3 years, and Air France deemed
that the aircraft had significant shortcomings, and was no longer safe to operate. Consequently they struck it from service,
and sold off or scrapped their remaining aircraft. Over the next few years the aircraft would
not stop having fatal crashes, in 1950 a SEMAF 631 was lost after its aileron couplings were
shaken loose due to vibration in the gearboxes. All 12 on board died. In 1955 the last operational 631 had its entire
wing separate from the fuselage due to windshear after flying into a tropical storm off the
coast of Cameroon - all 16 on board were killed. Four of the eleven aircraft had been destroyed
in fatal crashes, with one not crashing but still killing two people. Overall, in just 10 years of service, and
with only a handful of operational examples, the aircraft had resulted in the deaths of
101 people. The source of the crashes too, had not been
from a single fatal flaw, but from structural issues, vibration issues, a lack of de-icing
equipment, questionable manufacturing tolerances, and quite possibly more - from the aircraft
that disappeared over the Atlantic. Despite winning the contract it had been designed
for, and despite being a truly beautiful design, there was no denying that the Latécoère
631 was essentially, well, a death trap. It had never even been particularly reliable
or economical to operate. Maintenance had always also been an issue
with the aircraft, they had never been easy to keep going - in fact, two of the high-profile
crashes were on ferry flights to Biscarrosse for maintenance. This perhaps tells you everything you need
to know. Ultimately, the few remaining aircraft were
scrapped, and by 1956 not a single example remained. The Latécoère 631 was without a doubt a
marvel of engineering, and to this day captivates many aviation fans, considered to be one of
the most beautiful aircraft ever designed. Regardless, its protracted development only
served to delay the disaster that its service life would ultimately turn out to be - and
the 631 never lived up to the hopes of its designers. It did certainly have issues, and the decision
to ground the aircraft was certainly justified - but many wish that at least one could have
been preserved in a museum for us to see today. A flying boat representing the golden age
of aviation, the 631 now goes down in history as being an enormous, beautiful, death-trap. A huge thanks to my Patrons, on screen now,
for supporting the channel and Thankyou so much for watching this video of Aviation Deep
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