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Story of a Model Aircraft Designer
By: Andrew S. Rosz
This is a story about an R/C Model Aircraft Designer,
namely myself. As most of us in the hobby quite routinely build a plane from a kit,
or scratch build one from a plan, we are usually met satisfactory results at the
flying field with our new creation. But what about the people in the hobby that
take on the task of actually designing an aircraft starting only with their
imagination? After now having joined the ranks of these few individuals by
designing, building, testing, flying, and fine-tuning designs of my own, I would
like to share with you some of my experiences along the way. There is much that I
have learned.
Unlike a kit, there are no plans to go by. And with the
particular designs and building materials that I have chosen, there are no similar
designs or existing patterns to use as a guide; so every design detail is truly
unique. One of my recently patented designs is a 40-size flying wing. This design
was by far my most complicated design project I have undertaken to date. To begin
with, I wanted this design to emulate the B2 Stealth Bomber so the obvious first
step was to obtain photographs and/or pictures of the real plane. I had no luck. I
couldn’t find even one picture. Boy, we’re off to a good start here... So,
while at the Ft. Lauderdale Beach air show last year, I remembered that I had taken
a few photos of the real B2 as it did a slow fly-by over the beach; and that’s
all I had to go on. After about 20 hours on my CAD program, I realized that
designing a 40-size scale B2 was completely out of the question. Logistically, the
plane shouldn’t fly. Nevertheless, I pressed on. After making about 100
mathematical calculations concerning everything from the density and weights of the
various parts based on the materials I would be using, certain answers began to
present themselves such as appropriate wingspan, chord length, spar location, sizes
of control surfaces, wing loading, and center of gravity location. Mind you, design
considerations of these items for a wing aircraft is completely different and
unlike that of a conventional aircraft. Up to this point and like most other
aircraft designers, I usually designed only "normal" airplanes with a
wing, fuselage, and a tail where all these aircraft usually obey generally
agreed-upon principles of aircraft design and aerodynamics. After about another 50
hours or so on the drawing board, it was finally time to start cutting out the
pieces and building the plane. Then more problems; How do I attach the fuselage?...
Where should I place the CG?... What shape should the airfoil be?... How much
washout should there be?... Where should I place the wheels?...Having consulted
several "experts" on flying wings, it seemed that the only constant was
that there was no constant. So, despite many calculations, much was still left to
my "best guess."
One hundred building hours later, the plane was done and
ready to fly. Problems solved (so I thought), and the big day arrives... time for
the first test flight... Radio... check. Trims... check. Engine working OK...
check. Rolls straight... check. Well, the only thing left to do was to get it on
the runway, push the throttle foreword, pull back on the stick, and see what
happens. And that’s exactly what I did. It rolled... and rolled... and rolled...
right off the edge of the runway. And right in front of about of 100 people eagerly
awaiting the outcome of the first test flight. My heart sank. "Oh shit" I
thought... great... just great... this is great for my reputation not to mention my
ego. So I shamelessly went to retrieve my plane (no damage) to assess the
situation. After discussion with the "experts" witnessing the not-to-be
historic first flight, we all agreed that the position of the CG had to change. We
made the change and tried again. It rolled... and rolled... again, right off the
edge of the runway, but this time, it flew about 50 feet horizontally before coming
to rest safely in the grass. Again I thought, "Oh shit... now what should I
do." After being so scientific throughout the entire design process, I was now
desperate for answers and thinking "How the hell am I going to get this thing
off the ground." After more discussion with the "experts," we raised
the nose a little, moved the wheels a bit more forward, made some more trim
adjustments to the elevator and ailerons, and moved the position of the battery yet
another time.
Let’s try it again. This time we were met with success.
The plane lifted off smoothly, trimmed out easily, and flew beautifully. Come time
to land, descent was smooth, flair and touchdown went flawlessly and the end of the
first flight was met with congratulations from no less than a dozen people. At this
point, I knew that I had a winner of a design. During the second test flight, I put
it through some basic maneuvers including loops, rolls, and slow flight. It handled
exceptionally well and showed no undesirable tendencies. This again was met with an
incredible sigh of relief as well as more compliments from the crowd. Knowing that
I did not have to change or modify the basic design was truly a miracle; that is, I
got it right the first time. But the truth is, and despite all the math and
calculations, plain and simply, I got lucky. I’m sure there are many
aircraft designers out there that go through the calculations and build revision
after revision only to be met with continued failure. (Just look at how crummy many
of your commercially-available kits fly...) I can now truly sympathize with them.
It took me about five times as long to design and build this model as opposed to
simply scratch-building one from a plan. So why do aircraft designers put
themselves through this emotional roller coaster? Perhaps the award that I won at
one of our club meeting sums it up nicely... The award entitled "Dashing
Undaunted Model Busters" was unanimously bestowed upon myself when a model I
was flying flew straight into the ground under full power. I claimed; "It wasn’t
my fault." Yeah... yeah... yeah... they all said eagerly handing me the
coveted certificate and plaque to proudly display for a month. And after carefully
reading the wording the certificate, I now know why aircraft designers brutally
punish themselves by undertaking such seemingly senseless pursuits. The answer
comes from a quote on the certificate of which I would like to quote a passage from
same... "There can be only one reason why any man would put himself through
such agony – DUMB, real DUMB." How appropriate and ironically, how true. So
if you think you are DUMB enough, go ahead and try to design a plane of your own.
And if you are really DUMB enough like me, it just might make you come back for
more. I now have plans to design and build a new pattern ship. If everything goes
according to plan, it’s sure not to fly!
Incidentally, on June 1, 1999, the design of this aircraft
was awarded a U.S. Patent No. D-410,503. Go to my page on the U.S.
Patent Office Website and check it out!
***
~Andrew S. Rosz
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