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Pitch vs. trim in flight phases



 
 
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  #21  
Old May 16th 08, 07:55 PM posted to rec.aviation.piloting,rec.aviation.student
Tina
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Posts: 500
Default Pitch vs. trim in flight phases

Your description of yoke pressure is vastly different from that we who
fly ga aircraft experience, which explains why you do not understand
ga trimming procedures.

We feel the pressure on the yoke reducing as trim is corrected. You
don't. We maintain the desired attitude (note - "attitude" ) with the
yoke and trim away the pressure. You can't.

This is basic piloting, the notion of trimming away yoke pressure
happens in the first hour of flight training for a PP.
..
Is there any question as to why your pronouncements regarding GA are
viewed with suspicion?

On May 16, 2:49 pm, Mxsmanic wrote:
Robert M. Gary writes:
I'm not sure how you can without a force feedback joy stick. You use
the trim to remove pressure from the yoke.


As I've explained, I can trim until I no longer need to hold the joystick away
from the neutral position. The stick is spring-loaded, which provides a so-so
simulation of control pressure.

I've read that force-feedback sticks are so inaccurate that it's better to
just have a stick with springs.


  #22  
Old May 16th 08, 08:05 PM posted to rec.aviation.piloting,rec.aviation.student
Mxsmanic
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Posts: 9,169
Default Pitch vs. trim in flight phases

Tina writes:

Your description of yoke pressure is vastly different from that we who
fly ga aircraft experience, which explains why you do not understand
ga trimming procedures.


It is not "vastly different," merely different. Don't overestimate the
importance of minor differences. If such differences were that important,
then pilots would have to start learning from scratch again every time they
moved from one aircraft to another.

We feel the pressure on the yoke reducing as trim is corrected. You
don't.


Yes, I do. The closer I am to correct trim, the less I have to move the
joystick from its neutral position, and the less spring pressure there is on
my hand. When the aircraft stays put without me touching the stick at all, it
is trimmed correctly.

Is there any question as to why your pronouncements regarding GA are
viewed with suspicion?


How often do you fly with MSFS, and what configuration do you use?
  #23  
Old May 16th 08, 08:19 PM posted to rec.aviation.piloting,rec.aviation.student
gatt[_3_]
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Posts: 193
Default Pitch vs. trim in flight phases

Ken S. Tucker wrote:


Quick question, (it's been awhile since I've piloted)
is the trim (Cessna 152) in the center, right of the
pilot, and has zero mark to be set null in pre-flight?


Correct. (Well it has a "takeoff position" which is more or less center.)

In the '74 PA-28R I rent it's between the seats and harder to see, and
takeoff position is about "a quarter-inch back" on the slot since
there's no visible mark. I don't like the trim-wheel there. The first
time I flew in the right seat and reached for the trim handle I cracked
my knuckle against the door.


-c

  #24  
Old May 16th 08, 08:21 PM posted to rec.aviation.piloting,rec.aviation.student
More_Flaps
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Posts: 217
Default Pitch vs. trim in flight phases

On May 17, 7:05*am, Mxsmanic wrote:
Tina writes:
Your description of yoke pressure is vastly different from that we who
fly ga aircraft experience, which explains why you do not understand
ga trimming procedures.


It is not "vastly different," merely different. *Don't overestimate the
importance of minor differences. *If such differences were that important,
then pilots would have to start learning from scratch again every time they
moved from one aircraft to another.

We feel the pressure on the yoke reducing as trim is corrected. You
don't.


Yes, I do. *The closer I am to correct trim, the less I have to move the
joystick from its neutral position, and the less spring pressure there is on
my hand. *When the aircraft stays put without me touching the stick at all, it
is trimmed correctly.

Is there any question as to why your pronouncements regarding GA are
viewed with suspicion?


How often do you fly with MSFS


They have an airline?

Cheers
  #25  
Old May 16th 08, 08:40 PM posted to rec.aviation.piloting,rec.aviation.student
gatt[_3_]
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Posts: 193
Default Pitch vs. trim in flight phases

Mxsmanic wrote:


Yes, I do. The closer I am to correct trim, the less I have to move the
joystick from its neutral position, and the less spring pressure there is on
my hand. When the aircraft stays put without me touching the stick at all, it
is trimmed correctly.


That the general idea, but in an airplane the stick isn't generally
-moved- (except at very slow speeds); rather, pressure is exerted on it
by the pilot to counter the forces exerted by the airflow over the
control surfaces.

I recommended to somebody else that they call around the local flight
schools and see if they can find a Frasca-type simulator like this one
http://www.frasca.com/body/TruVision170.Lo.jpg and spend a half-hour or
so in it. The pressure feedback is strikingly similar to that of a
small airplane, and you'll get a good sense of the correct feel as well
as the correct use of trim to alleviate control pressure.

"During flight, it is the rudder -pressure- the pilot exerts on the
control yoke and rudder pedals that causes the airplane to move about
the axes. When a control surface is moved out of its streamlined
position (even slightly), the air flowing past it will exert a force
against it and will try to return it to its streamlined position. It is
this force that the pilot feels as pressure on the control yoke and the
rudder pedals." Airplane Flying Handbook

I imagine it would be pretty expensive, but I'd really like to see a
motorized flight sim yoke that accurately represents control surface
pressures. I have all the hardware (spare Battlebot parts) to make a
dual-axis prototype, but not enough knowledge of the software interface
or specific pressure values.

-c
  #26  
Old May 16th 08, 08:45 PM posted to rec.aviation.piloting,rec.aviation.student
gatt[_3_]
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Posts: 193
Default Pitch vs. trim in flight phases

Mxsmanic wrote:
Tina writes:

Perhaps the difference between the MSFS and reality is the notion of
adjusting trim to take pressure off the yoke is one of those 'it
doesn't matter in simulated flight' issues.


Some controls for use with the sim, including the Saitek X52 joystick that I
have, are spring loaded, and MSFS behaves in such a way that you must maintain
pressure against the springs if the aircraft isn't properly trimmed.


I don't know how that compares to the Saitek Aviator which is what I
use, but I'm thinking of removing the springs and replacing them with
stiffer ones to make it a bit more realistic.

-c
  #27  
Old May 16th 08, 08:49 PM posted to rec.aviation.piloting,rec.aviation.student
Ken S. Tucker
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Posts: 442
Default Pitch vs. trim in flight phases

On May 16, 12:19 pm, gatt wrote:
Ken S. Tucker wrote:

Quick question, (it's been awhile since I've piloted)
is the trim (Cessna 152) in the center, right of the
pilot, and has zero mark to be set null in pre-flight?


Correct. (Well it has a "takeoff position" which is more or less center.)

In the '74 PA-28R I rent it's between the seats and harder to see, and
takeoff position is about "a quarter-inch back" on the slot since
there's no visible mark. I don't like the trim-wheel there. The first
time I flew in the right seat and reached for the trim handle I cracked
my knuckle against the door.


Ok thanks.
I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!
Regards
Ken
  #28  
Old May 16th 08, 08:49 PM posted to rec.aviation.piloting,rec.aviation.student
Dudley Henriques[_2_]
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Posts: 2,546
Default Pitch vs. trim in flight phases

gatt wrote:
Mxsmanic wrote:
Tina writes:

Perhaps the difference between the MSFS and reality is the notion of
adjusting trim to take pressure off the yoke is one of those 'it
doesn't matter in simulated flight' issues.


Some controls for use with the sim, including the Saitek X52 joystick
that I
have, are spring loaded, and MSFS behaves in such a way that you must
maintain
pressure against the springs if the aircraft isn't properly trimmed.


I don't know how that compares to the Saitek Aviator which is what I
use, but I'm thinking of removing the springs and replacing them with
stiffer ones to make it a bit more realistic.

-c


Ah yes......but at what airspeed? (slugs dynamic pressure vs unboosted
control surfaces :-))

--
Dudley Henriques
  #29  
Old May 16th 08, 08:57 PM posted to rec.aviation.piloting,rec.aviation.student
Steve Foley
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Posts: 563
Default Pitch vs. trim in flight phases

"Mxsmanic" wrote in message
...
Tina writes:

Your description of yoke pressure is vastly different from that we who
fly ga aircraft experience, which explains why you do not understand
ga trimming procedures.


It is not "vastly different," merely different. Don't overestimate the
importance of minor differences. If such differences were that important,
then pilots would have to start learning from scratch again every time

they
moved from one aircraft to another.


It is, in fact, vastly different.

I have flown many different aircraft, and have never had to ask someone how
to trim the plane.

I recently purchased FS2004, and if you care to check google groups, you'll
see I did need to ask how to trim.

  #30  
Old May 16th 08, 09:16 PM posted to rec.aviation.piloting
BDS[_2_]
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Posts: 149
Default Pitch vs. trim in flight phases


"Mxsmanic" wrote

Yes, I do. The closer I am to correct trim, the less I have to move the
joystick from its neutral position, and the less spring pressure there is

on
my hand. When the aircraft stays put without me touching the stick at

all, it
is trimmed correctly.


That's the difference, and it is a big difference.

In an airplane you might be holding forward pressure on the yoke at say 2
lbs to hold a particular attitude. As you start rolling in forward trim the
force required to hold the yoke in the position it is currently being held
diminishes until it is gone altogether. The yoke never moves but the force
required to hold it where it is diminishes to zero.

In your sim what happens is that as you roll in forward trim you have to
move the yoke back to compensate which results in less spring pressure based
on the new position of the yoke - the previously held desired attitude now
occurs with the yoke in a different position. This is not at all how it
works in an airplane, and not at all how it feels to the pilot.

In addition, in my experience the springs in these toy yokes and joysticks
do not feel at all like normal control pressures in an airplane - the "feel"
is all wrong and the force curves are not the same.

BDS


 




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