Red = Maximum
Blue = Minimum...
After some questions from readers here I thought it would be helpful if there
was
some background information on these black op studies its often forgotten that
not everybody shares the same level of insight about things but the desire
to learn and understand stuff is often there.. in the end its all just stuff
and incidental but we need to fill our time up with something while here so I
guess that is the reason and explanation of the Why I have the time and
curiosity
to scientifically and empirically explore the efficiency of flight and am
very fortunate and grateful to fly a Europa, and to contemplate how good might
it be doing what it does?
The other aspect about this is reading about all these various Mods Europans
have
devised, and do they actually do what we think they do? Why dont we go find
out?
Flight is such a truly amazing thing it wasnt until experiencing weightlessness
while scuba diving that I experienced an aha moment of multidirectional movement
through a fluid space where there was no up or down, left or right just
movement,
and a sense of freedom so I spent my time tumbling around and being comfortable
with being upside down looking at the bottom of the sky and transition
layer overhead.
For the next 15 years I decided to explore fluid environments and sketch out
fresh
and challenging ideas of how to move through fluid mediums several concepts
were developed and intensively studied through to proof of concept.. one of
the concepts was an aircraft that came out of a doodle one night and set the
path
for a 20 year study tour of the concept and finding some existing similar
correlate ideas to garnish valuable test data from glider models were built from
different materials, which proved very stable with great glide ratios.. the
concept was developed further and tuned and sent into a digital environment for
further analysis and flight testing within Xplane.. so with the testing proving
viable and efficient I thought if this thing is going to be built I better
learn to fly before its ready to fly!
A few years ago the politicians decided it would be a good idea to lock
everybody
in their domiciles and shut the world down and destroy small business all over
the world it didnt work out too well for mostly everybody, but while all this
was going on I decided it would be a great opportunity to use this historic
moment to learn to fly; and have not stopped since
Starting off in a Samburo was good enough moving into a MotorFalke was like
driving
an S2 Landrover all over agian things were moving too slow so it was off
to ultralights and into a Tecnam 2002 Sierra; and they fly really well after
looking
at many types of light aircraft I was not really excited about the Europa
at first but after reading about it and having an in depth study of its story
and comparing it to most other stuff out there in its class purchasing 181
when the politicians unwittingly caused the used aircraft market to dump 50% was
a no brainer; havent regretted it one bit, but every time I flew it I was not
feeling totally confident with my abilities; so after working it out more more
training was pegged in.
Strapping myself into a Pitts 2A and tumbling around in the sky for a few days
knocked me out of the world of two dimensional fatal flying and into a
unidirectional
appreciation of the fluid medium once again with another aha moment of
realising there is no up or down or left or right; just Attitude, and that was
it everything else was incidental and I came out the other end a much more
confident
aviator for it... I felt confident, I felt sufficient.
Experiencing flight in a fixed wing aircraft has brought me to the conclusion
that
rotor wings have their place and purpose and giant drones as we currently
know them have no use-case; its an orphaned solution looking around the world
for a problem so my motorbike for the sky idea has been thrown in the bin it
will
work, but it has no use-case; like the flying car...
There are many ways to test and prove stuff since the mid 1980s stuff has been
designed and proofed within a digital world of CAD (Computer Aided Design)...
its a mathematical nightmare that spits out stuff when buttons are pressed in
a set sequence and thats about all there is to it knowing what buttons to press
takes a while to get right but practice gets results, and more practice gets
more results and it has taken thousands and thousands of hours to get to where
I am and I still consider myself a mediocre hack at this stuff, but within the
field of Design Im happy to sit way out back riding the big scary swell of
the yet unknown without apprehension.
CAD is married to FEA (Finite Element Analysis) or FEM (Finite Element Method),
and CFD (Computational Fluid Dynamics), its a method of mathematically solving
complex relationships between Materials (Model) & Environments (Computational
Domain); and thats about it The environment and material is contained within
a specified 2D or 3D perimeter and divided up into a Mesh this Mesh is made up
of a cluster of mathematical positional points (Nodes) within the Domaineach
set of Nodes makes up a Cell of at least three Nodes, and these Nodes are all
interrelated interconnected mathematically providing a path of continuity to
all the other Nodes. Blah Blah, Blah Blah Blah All that is important to know is
that the finer the Mesh the more accurate the results (Solution) will be to
a Real World scenario. Running conclusive simulations involves refining the Mesh
to a point where the answer is sufficient to guide the task onto the next step.
As the Mesh is refined it takes longer and longer to spit out a result. Getting
to 95% accuracy is good enough while developing concepts; 99% is enough
to expect bankable results.
There are different types of Meshes used for different types of Solutions;
Steady
State (static) and Transient (moving mesh) Steady State is fast and generally
used for static primary mechanical stress/strain and fluid flow analysis; it
is a moment in time study. A Transient Mesh is generally used for Time dependant
studies (gas turbine engine op's) and takes a lot longer and consumes a lot
more computer power to solve; so it is generally undertaken toward the end
of a design cycle using industrial computers or daisy chained servers In these
studies we are mostly using CFD for aerodynamic related stuff, and FEA for
structural
load related stuff.
So what about all these coloured rainbow images and data numbers thrown up; how
should they be interpreted? What does it all mean?
Blue = Minimum
Red = Maximum
Generally there will be a scale attached to an image that determines what type
of analysis is being presented (Velocity/Acoustic Power/Pressure/Stress/Strain)
along with these Min/Max figures; and the Min/Max numbers can be manipulated
to focus into a narrower band of data. This band tuning is done to filter out
useless information that may be outside of what is required. For example, an
analysis may be undertaken at a free stream velocity of 51m/s (100kt) over an
aerofoil, so our Min (blue) will be 0m/s while our Max (red) will be somewhere
around 75m/s, so the Max on the scale will be set at 75m/s to reveal higher
velocity
air moving over the lifting surface; if we set the Max scale at 50m/s
most of the surface will turn red and be useless. So the end result is purely
a contrast of data; and this is pretty much generic with all the rainbow images.
With the CFD images there may often be thin dark lines running over the surface.
These represent the directional flow of the fluid across the Boundary Layer
being the area at the surface and above to about 0.25mm to 1.00mm; it can be any
depth specified, but is generally extremely thin and is the critical area where
fluid separation is mostly looked for as we approach the surface the fluid
eventually slows down to zero... Other images may be taken from a slice plane
in any combination of XYZ direction, and can be used to study the movement of
fluid by layer similar to the way a medical CT scan works.
Several data sets most used in the above studies are Velocity, Pressure,
Acoustic
Power, and are all related to how the movement of Fluid is relating to the
Model. Mostly Velocity is used to determine areas of stagnant fluid flow and
turbulence.
Other data sets looked at are Drag and Lift in a very rudimentary way and unless
noted will mostly be accessed without adding Sin or Cos equations to the
Solution.
The reason being that all the Fluid studies are comparative only and not
Finite, meaning each Solution result is contrast against another to determine
whether or not an adjustment is more or less aerodynamically efficient.
Everything begins with Alpha Alpha is the Angle of Attack of the free stream
fluid
against the Model If Alpha = +/-12 then that means the free stream is meeting
the model at +/-12 degrees to a specified orientation of the Model within
the Computational Domain. Alpha=12 generally will mean the AoA of the wing is
12deg Pitch Attitude refers to the fuselage orientation relative to the free
stream,
so Alpha will equal Attitude +-Incidence... There are a multitude of other
Greek scribbling but Alpha and Velocity is pretty much all that is needed
to be aware of.
Fluid Density 15C at 0 AMSL unless specified.
Turbulence this is a setting within the Solution setup matrix and is set at 5%
because we do not exist or fly within a vacuum, so a little randomness provides
for a more realistic CFD related result.
Failures Computer says no, often due to surface issue with the model, so hours
are sometimes spent searching through the model for microscopic inconsistencies
(Dirty Model) and sometimes its easier to just rebuild the model when they
cannot
be found.
FEA related images are similar to above without the inclusion of a Fluid Medium;
they are simply a surface image of the mechanical component or a slice taken
through the component.
FEA/Mechanical results are looking at Material Elasticity primarily via
Stress/Strain,
reviewing the Tensile Strength of a component relative to the Materials
Yield Strength (Force applied at which the component material does not return
to original state), and Ultimate Strength (Force applied at which the component
material fractures) Other criteria looked at relates to Modal (Harmonic) aspects
of a component and which resonant frequencies experienced by a component
may lead to early failure or emission of natural occurring frequencies
transmitted
into a Fluid Medium as Acoustic Power.
Every decent scientific study needs a control pig to provide a baseline data
point
for this purpose we have two pigs, sorry plugs one with a wing root flare,
and one without; and they may often be referred to for a result's
compare/contrast
purpose. Both these plug models are devoid of all additional airframe features;
so they are as slippery as a Europa can be.
FAQs
What about propeller swirl? not included and if it is it will be further down
the
line during Time Dependant solutions.
How did you create the digital model? With a plum bob, ruler, set square, tape
measure, piece of dowel, CAD program, lots of time, and a pencil.
Do you work for the NSA or MI6 as an operative? No
Should I follow your advice or believe any of the information presented within
any of the Obsidian Files? Never.
And thats about it for the preamble and FAQs if anyone has anything to add that
may have been missed feel free to add it on.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510802#510802
|