on october the 7th 1932 a highly
experimental aircraft prepared for its
first flight
this was the steeper caproni or the
caproni steeper depending on who you
talked to
it was designed by luigi steeper and
built by giovanni caproni's aircraft
company
though it may have looked like this
strange love child of a gb racer and a
dustbin it was in fact an innovative
design that despite appearances was
completely flyable and represented an
early example of ducted fan technology
now while the steeper caproni may have
been an odd blustery and somewhat
terrifying machine the sponsor of
today's video endel is a far more
relaxing affair do you have a hard time
focusing on your daily tasks do you find
your productivity suffering due to
stress or anxiety
or do you find that the sweet embrace of
sleep never quite arrives and you spend
six hours staring at your ceiling in a
muted rage
endor could very well be the solution
for you
endl is an environment-based non-profit
app that takes everything we know about
sound and combines it with cutting edge
technology the app provides real
real-time personalized soundscapes
designed to help you relax focus and
sleep it's informed by science created
with science and backed by science
the app has five modes wind down focus
relax sleep and move
now it won't come as a huge surprise
that reading through dense aviation
textbooks for six hours a day can get
pretty dry and as i am easily distracted
by pretty much everything under the sun
i found the focus mode on endless app
particularly helpful
the soundscape was really really
relaxing and it sort of enveloped me but
not in an intrusive way and i was able
to blast through hours of research
without interruption or my mind
wandering
as an added bonus i also found it much
much easier to switch off and fall
asleep at night using endless sleep mode
which has been a blessed relief seeing
as i've currently got a family of
possums performing a tap dance routine
on my roof
speaking of added bonuses the first 100
viewers to download endl using the link
below will get a free week to try out
and all for themselves and enjoy all of
those soothing soundscapes once again
thank you to endl for sponsoring today's
video and now let's take a closer look
at the caproni steeper
in the early 1930s the italian fascist
government wanted to showcase the
success of italian technology
and in particular they wanted to show
off their best advances in the field of
aviation a topic of international
prestige
italy had already achieved notable
success with commercial aircraft such as
the savoya marquetti s55
but the air ministry wanted something
that was cutting edge something that had
not been attempted before
and thus their attention was quickly
caught by a radical new design submitted
by luigi stipa born in 1900 luigi stipa
was interested in engineering from a
young age
unfortunately the first world war
interrupted his education and he spent
the latter years of the war serving as a
sharpshooter following this he returned
to his education and spent the post-war
years earning academic degrees in
aeronautical hydraulic and civil
engineering he then found himself a job
with the italian air ministry where he
worked his way up to the position of
general inspector of the engineering
division during the mid to late 1920s he
began to work on several theories for
making aircraft more efficient
as a hydraulic engineer he knew that the
velocity of a fluid increased as the
diameter of the tube through which it
passed narrowed
called bernoulli's principle the
relationship between the velocity and
the pipe diameter was a well understood
axiom of fluid dynamics by the 1920s
applying bernoulli's principle to
airflow steeper believed he could
increase the efficiency of an aircraft's
engine by directing the prop watch
through a venturi tube
steeper called his concept an intubed
propeller
he designed built and tested several
aircraft models that featured this new
concept
and after multiple iterations had gone
through rigorous wind tunnel experiments
steeper believed he had worked out the
optimum shapes which the propeller and
tube would be designed to as it turned
out the optimal shape for the tube's
inner surface turned out to be almost
exactly identical to that of an aerofoil
and so in many ways the tubular fuselage
of his design essentially resembled that
of a wing that had been rolled up into a
tubular shape
steeper published his findings in the
bravista aeronautica along with design
drawings for a single engine test
aircraft
he then approached his superiors at the
air ministry about the possibility of
building his plane and the minister for
aeronautics keen to showcase new
innovations almost immediately agreed
the decision was made to build a small
aircraft that was to be powered by a 120
horsepower engine
this was not the ideal outcome for the
realization of the design but rather it
represented a compromise
firstly building a smaller aircraft
would of course save money and if the
endeavour turned out to be a failure
then the loss would be reduced
and secondly there had been no major
wind tunnel tests done on larger
complete models and so there was no data
available to determine the
maneuverability aerodynamics and the
general behavior of a larger design
however on the flip side it was
acknowledged that steeper's design was
written out with larger aircraft in mind
and indeed it was considered poorly
suited for smaller ones
but with the ministry reluctant to
finance a larger project for the reasons
mentioned just before luigi stipa had to
make do with what he had
eventually he came to an agreement with
the air ministry and they contracted the
caproni aviation company to construct
the experimental prototype
as regular viewers of this channel
already know count gianni caproni was no
stranger to experimental designs
you only have to look at the ca 16 over
plano or the ca 90 to get clear evidence
of that
and as a result of these adventurous
designs his company was probably the
most qualified in italy to take on the
challenge of realizing steeper's theory
in terms of its construction the
aircraft in general was rather simple
but it featured some notable changes
from the wind tunnel models that i will
cover shortly as mentioned earlier the
tubular fuselage resembled a wing that
had been rolled up and as such its
construction closely resembled that of
normal wings as well
it had two strong main rings which could
be considered large circular spas
on these spas were mounted longitudinal
ribs which were similar in design to
wing ribs and these were braced by a
series of smaller spars which were again
circular like the main ones
the elliptical wings looked almost
comically flimsy but that was only a
visual effect courtesy of the fuselage's
size
these wings were built in the
traditional manner being made of wood
with a fabric covering and to improve
strength the wing spars ran along almost
the entire span passing through both the
tubular fuselage and the engine nacelle
itself
at the rear the rudder and horizontal
stabilizers were mounted onto the
trailing edge of the fuselage
it was hoped that by placing the rudder
and elevator in the path of the air
pushed back by the propeller they would
allow a superior level of control and so
in turn the size of the control surfaces
could be reduced in the end this
reduction would never take place and in
fact it would be later suggested that
their size be increased rather than
decreased
the 120 horsepower engine took the form
of the four-cylinder de havilland gypsy
iii
this drove the so-called intude
propeller which was a two blade fixed
pitch wooden unit that fit snugly within
the dimensions of the fuselage this
engine was supported by a frame that was
connected along with the wing spars to
the main circular spas of the fuselage
when first completed the engine was
housed in a small nacelle however there
is evidence that this was removed on
multiple occasions though it is unclear
if this was to test the effects of the
aircraft's handling or if this was due
to some sort of heating or cooling issue
now i mentioned earlier that the
prototype featured several differences
compared to the original wind tunnel
models
some of these differences are worth
noting as they directly impacted the
performance of the aircraft
firstly to simplify the construction the
tubular fuselage was redesigned to be
symmetrical in steeper's original design
the fuselage was dissymmetrical so that
it could generate a certain amount of
lift even at zero angle of attack but
with the new changes this lift was
reduced while at the same time overall
drag increased
secondly the wings were braced by four
steel wires whereas on the original wind
tunnel model this was not the case
it's unclear whether this was an
oversight by a luigi steeper or whether
it was the result of further
investigations that deemed it necessary
to reinforce the wings in this way
regardless of the decision this and the
changes to the fuselage affected the
overall drag which meant that the
estimated top speed climb rate and
general handling characteristics of the
aircraft would not match the predictions
of the earlier wind tunnel tests but
even with the negative effects of these
modifications the plane was expected to
be perfectly airworthy and so
construction continued as planned
for those who first gazed upon it it
must have been a rather strange sight
and while caproni was silently adding
another sticker to his weird aircraft
design bingo card the tubular plane was
made ready for its first test flights
the date of the first flight was october
the 7th 1932
and despite some suspicious glances from
onlookers the pilot already had some
praise for it before it even left the
ground
since the propeller diameter was the
same as that of the fuselage the steeper
caproni sat very low to the ground and
thanks to a fairly wide undercarriage
this meant that it had excellent ground
handling characteristics
that being said it did look rather
comical when it was being taxied around
the airfield before taking off
flying the aircraft was caproni test
pilot domenico antonini a veteran test
pilot who had flown many of caproni's
more bizarre designs such as the huge
ca-90 biplane for example
after pottering around the airfield to
get a feel for the engine and the
throttle antanini powered up and the
barrel-like plane took off for the first
time
overall the aircraft behaved well in the
air and antonini found it easy to handle
following the first successful flight a
series of test flights were conducted to
gather data and evaluate the soundness
of luigi's steepest theory
these first tests did indeed confirm
that the design seemed to make more
efficient use of the engine compared to
a more conventional design
though the redesign of the fuselage had
reduced the additional lift it provided
it still created enough that it had a
superior climb rate over a conventional
aircraft with the same engine and it
also had a very low takeoff and landing
speed of just 68 kilometers an hour it
was also incredibly stable in fact it
was sometimes too stable with subsequent
test pilots complaining that it was
difficult to pull the aircraft into
banked turns
what was unknown to both steeper and
caproni at the time but was later
revealed by further testing was that the
tubular fuselage generated far more lift
than expected as such the required wing
area for stable flight was less than
what was designed and had further models
being built the overall wing size could
have been much smaller
although the design increased the
efficiency of the aircraft in terms of
engine power required for lift the
design also created so much drag that it
essentially canceled out any of its
benefits
as a result of this the aircraft was
slower than expected reaching a top
speed of just 131 kilometers an hour
with the engine threatening
disintegration if it was pushed any
further
some of this aerodynamic drag was
created by the modifications made during
construction but some of it was created
by the intubed propeller design in
general
ultimately the low-powered engine and
bulky propeller were not enough to take
advantage of bernoulli's principle and
generate superior thrust
and so when the aircraft was handed over
to the regia aeronautica for testing it
failed to outperform conventional
designs
though it was reviewed favorably by air
force test pilots the decision was made
to cancel further development and no
additional prototypes were built
this was a huge disappointment to
steeper and caproni as well who had come
to appreciate the potential of the
design
steeper had designed and built several
models for larger aircraft specifically
flying wings equipped with two or four
issued propellers and they tried to
secure funding for a new project however
these attempts ultimately failed
had a larger prototype been built it
could well have been very easy to fly if
the steeper caproni was anything to go
by but this flight of fancy would never
come to pass
though the air ministry didn't embrace
steeper's design it didn't stop them and
the italian government from using it as
a propaganda tool
steeper patented his intuit propeller
design in germany and in the united
states and his work was published in
multiple countries in fact a large
amount of my source material comes from
a naked technical memorandum that was
written up in 1934
unfortunately this remarkable aircraft
was eventually scrapped but a three to
five scale replica was built in
australia in the 1990s
it was built by lynette zakuli and
aerotech queensland and it made at least
two flights in 2001
it's unclear if the replica was ever
flown again after this but it can be
found on display at the toowoomba
airfield which is not too far away from
where i live so maybe i'll do a
follow-up video where i go and pay to
visit
although italy made no further efforts
to develop steeper's design a more
advanced derivative would be realized in
1940 though the caproni campini n1 was
nowhere near efficient enough to be
practical it did make use of a ducted
fan compressor buried in the fuselage
and by adding additional fuel to a
combustion chamber in the tail it gave
italy the laudable claim of producing
the world's first afterburning aircraft
but that's a story for another day as
always thank you all so much for
watching and i also apologize if my
voice sounds a bit off with this one and
for the next few videos right before i
went away on my holiday i started coming
down with a cold which obviously makes
my voice sound a bit more rubbish than
usual so apologies for that and of
course thank you all to the patrons
including the wing command to tie
patrons i shall be updating the list as
soon as i get back home but as always
thank you all so much for watching and
i'll catch you all next time goodbye