Well, the first reaction I'd have is that aircraft experience does not apply
here. I have a bit of Av background also -- my military time was in Navy
Aviation (no I did not fly, but I was around those who did), and my baby
brother is an F1 air racer.
Our cars don't pull the g-loads a jet pilot encounters. In fact, that jet
pilot's g-loads tend to be vertical as he is tilted almost 90 degrees over
when doing a fast, tight, high-load turn. It's also why they wear G-suits, to
prevent the blood from rushing out of the brain and into their legs and making
them black out. Not a problem we encounter much. Our G-loads are lateral, and
the Kirkey [not Kirby] is designed exactly for that.
Said pilot is also generally flying with an arm position that has his elbows
by his ribcage, a very relaxed position. A race car's steering wheel tends to
be roughly chest-high while the jet pilot's joystick is down around his navel.
So we tend to sit reaching out to the wheel. My old seat had me reaching so
far my arms were almost straight out. Virtually all leverage of turning the
steering wheel was in the shoulder muscles (I was younger then too!). Now my
upper and lower arms are almost 90 degrees at the elbow, and I have better
leverage turning the wheel using arm muscles.
Look at an in-car at a NASCAR race. They sit so close they often have their
elbow ON the wheel, giving them even more leverage as they turn the car. These
are guys who are in their car 3-4 hours at a time, not a half hour like we
do, so they have really studied how to last that long while conserving energy.
That seating position is a major aspect of that, and those guys sit straight
up. Open-wheel racers (F1, CART IRL) tend to be more straight-arm, but their
wheel takes a one-inch turn to get around most corners.
The G-loads our Spitfires generate are closer to Piper Cub than F18. So that
is of negligible concern to us. Comfort and leverage are much more important.
That said, the real factors determining whether your seat should be straight
up or tilted back has to do with two aspects -- how far your hands reach to
the wheel (you want an arms-bent position) and how far your legs reach to the
pedals (you want pedal to the metal - gas & clutch -- at full extension but
without going tippytoe to do it). For me to maintain the arm position I now
want, to have the seat tilted would mean moving it forward and that would
cause me to sit bowlegged (which I already do slightly anyway). In my case, it
is as if the back of the seat were located in the same place (old seat vs.
new) but I rotated the upper portion forward. Thus my legs/lower body are no
closer but my arms/upper body are.
When we installed my Kirkey, first thing we did was just put it on the flor of
the car, loose, and I sat in it at various positions until I decided what was
comfortable and best leverage. Then we marked where it was and drilled the
bolt holes.
--Rocky
----- Original Message -----
From: Group44TR7@aol.com
To: rocky@tri.net
Cc: fot@autox.team.net
Sent: Tuesday, October 21, 2003 2:32 PM
Subject: Recommended Seat Position
Rocky
I found your comment about the physical position of the seat (level
on the floor) to be very interesting. It was very recently recommended to me
that I have a new seat inclined slightly backward. The person giving the
recommendation, who has aircraft experience, says that combat pilots seats are
inclined backward because it is a better position for a person body under the
stress of high speed turns.
Does the Kirby, by design, already has some inclination in it when
position on the floor? Or should I be seeking some second opinions about the
positioning of the seat.
CP
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