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I read Gary Casey's message about
safety and aircraft improvements with interest. I'm a mechanical engineer
in the automotive world, but since I was born with my mother's ability to put
together a semi-coherent sentence, I was drafted into Marketing
(horrors!). Anyway, when I was a practicing engineer, I was pretty
sharp. Sharp enough to think that most of Gary's improvement suggestions
are best left on the idea shelf for the factory to pick through.
Speaking as a 360
builder/flyer, I think the best thing we can do is build these planes to
the plans. Then get fresh eyes to look over our shoulders. Then get
a test pilot to make the first flight and train us into the airplane. Then
fly within our training (and the plane's) limits. I thought maintenance
went without saying, but evidently that must in fact be said. If you go
adding things like geared rudder pedals to backstop an egregious error
elsewhere, where's the sense in that? That rudder cable is not going to
break no matter how hard you apply the brakes. But it will come off the
firewall attach if you didn't fasten it properly or didn't swage the end
properly. Or if you cut it part way through while fixing something
else. Pay attention and follow the manual carefully. On the other
hand, your time consuming gear system adds weight, friction, lots of time, and
new failure modes most likely far scarier than what it was intended to
solve.
Likewise, don't go adding extra bids,
especially of a dissimilar material like unidirectional carbon, unless you are a
structural engineer and have modeled the structure and your contemplated
change. We've talked about this one before. Stiffening one area can
chase loads and failures to unexpected places. Don't mess with a design
that has demonstrated itself to be successful. Sure, if your test flight
shows you've got a heavy wing, fix it with one of the usual fixes (small flap
adjustment for instance). Learn what your plane does at the stall and then
stay away from that. Count yourself lucky if the stall characteristics
don't frighten you. These aren't training airplanes.
It would be different if the design
was brand new and untested. Then, maybe your individual expertise may
be substantial when compared to the body of knowledge and experience manifest in
the flying airplane population. But that's not the case now, I would
suggest. Not because your abilities are diminished, but because hundreds
of airplanes and a decade plus of experience and successful performance say
you'll be hard pressed to improve on it. It's far more likely you'll
create new and nasty problems.
On the other hand, do serve up your
suggestions to the factory. They are in the best position to determine
value and could incorporate them into a new model, if the ideas are really
worthy. I would not want to conclude that we can't learn regarding the
design, but leave the modifications to the few people who really know what they
are doing (that's not us). Rather, we should spend our time building well
and flying well. That's time well spent. By the way, obviously
non-structural, non-aerodynamic changes are fine. If you aren't sure
you know the difference vs. changes that affect aerodynamics or the
structure's performance (or any other aspect of function like fuel delivery),
just stick to the plans.
Best,
Ed de
Chazal
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