On Sun, 10 Sep 2006 07:28:36 +0200, Mxsmanic
wrote:

RK Henry writes:

No, you can't. Feeling the movement is entirely the point.

That's a matter of individual preference. For instrument flight,
feeling the movement is not only unnecessary, but potentially
hazardous, if it distracts attention from what the instruments are
saying.

If you could fly the airplane by reference to the instruments
without feeling movement, then instrument training would be easy.

It is.

But it doesn't work like that in the real world. The airplane
inherently imparts accelerations that are inconsistent with the
indications of the instruments.

He's correct, particularly in training. You are down low, it's hot,
and you are getting bounced around. Light and shadow play tricks such
as flying through light cumulus. The light flickers and is brighter on
one side than the other. Our minds tell us that brighter is up, but
it's usually off to one side.

I have a great photo that was shot by a friend from the back seat in a
Cherokee 180 when we were IFR in actual IMC. It was a relatively thin
layer of cumulus that wasn't supposed to be there according to the
forecast. At any rate, every one in the plane appears to be leaning
until you look at the AI. The two of us in front are aligned with the
AI while the photographer was the one with the "leans".


Which ones?

AI, TC, and DG. Both light and motion can give inputs to the body
that conflict with any or all of these three instruments. It takes
time, but you, or rather your mind, become acclimated to accepting the
instruments as input rather than the bodily senses as it does when
flying VFR.



Part of the training process is learning to ignore the
sensations and trust the instruments.

That rather conflicts with the preceding statement, doesn't it? If
the instruments don't accurately indicate accelerations, why trust
them?

Mainly it's because it's not a just matter of acceleration but the
summation of a multitude of inputs. For instance, I can put a plane
through a barrel roll while holding positive G all the way through. If
a passenger were not looking outside they would never know we had
rolled a complete 360 degrees. Bob Hoover used to do that with a glass
of water setting on the glare shield and the water stayed pretty much
level in the glass even when inverted. I'm not and never will be the
pilot Bob is.

You can also do a loop and maintain positive G all the way around.
What the person will feel is a pull up, a feeling of leveling off
(when inverted) and a feeling of pulling up again as you start down
the back side of the loop.

The really strange part about a loop for some one who gets used to the
motion is it often feels like the earth did a loop around you instead
of you doing a loop above the earth. In the G-III that would be a
maximum of about 4 1/2 Gs when the nose reaches a point about 45
degrees before level flight at the end of the loop.

I used to do a lot of photography. I shot road rallies for several
years and spent some time tied onto a helicopter. The pilot would
bank and use his own down wash to stop and hang there momentarily.
(gun ships do the same). Instead of me feeling like I was tipping
forward it was as if the earth tipped up in front of us.


It can be very difficult for the untrained pilot to make this
mental adjustment in the seconds before making a crater in the
ground, which is why getting the training beforehand is so important.

Like I said, the idea is to trust the instruments.

That is extremely difficult to do when your body is telling you
otherwise even when everything in the plane is working right. Add to
that a case of vertigo and your thinking gets stuck in the mud. It
takes a lot of conditioning before your mind is willing to accept the
input from the instruments over what your body is telling you. Add to
that the work load of climbing or descending to the proper altitude
and turning to the proper heading let alone holding heading and
altitude and it can become a high pressure environment at times. Some
never make that transition.

I fly high performance. I've let a lot of other pilots fly the Deb.
It's a rare pilot who has been flying fixed gear planes that wont soon
have the Deb doing 2Gs out of the bottom and zero over the top in a
PIO. They are used to looking at the VSI. That doesn't work in
slippery airplanes. More than one has had me saying to my self: I will
not get sick in my own airplane... I..will.. not...get ... sick...
in... my ... own airrrr...plane....

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com