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#161
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Pitch vs. trim in flight phases
On May 30, 3:50*pm, Robert Moore wrote:
The Boeing 707, and perhaps others, trimmed in this same fashion. Trim...Relax....Trim some more...Relax...Do it again....... I'm not familiar with the 707 systems, but a friend of mine flew the DC-9 and told me it had the same jackscrew trim arrangement as the short wing pipers (scaled up of course) so I would expect it might behave the same way. Anyone who has actually flow the DC-9 care to comment? Michael |
#162
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Pitch vs. trim in flight phases
"Michael" wrote in message ... On May 31, 10:56 am, Tina wrote: The overlooked or ignored difference is if one turns the trim in the wrong direction in a real airplane pressure on the yoke increases. No, this is not universally true. I've flown airplanes where this is not true, and clearly so has Robert Moore. These are certificated airplanes ranging from light piston singles to transport category multiengine jets. Oh, if you keep doing it long enough, yes, you will eventually feel something - but if you depend on this as your primary cue, you will never get it right. You just need to know which way to adjust the trim, and you need to keep moving the yoke to maintain pitch attitude. Pilots are trained to trim to reduce yoke pressure -- it is obvious and becomes instinctive. Sims of the everyday variety do not provide that feedback. And neither do some airplanes. If you are trained to depend on that cue, you are SOL in those planes. We do not live in a single cue world. Michael ******* Well then, once you get to the point of having no pressure on the yoke, what's the point of trimming any further? |
#163
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Pitch vs. trim in flight phases
On Jun 3, 8:32*am, "BDS" wrote:
Well then, once you get to the point of having no pressure on the yoke, what's the point of trimming any further? The point is not that you get to where there is no pressure on the yoke. The point is that moving the trim without moving the yoke will never get you there. You have to move the yoke as you move the trim to get to where the pitch is correct without applying pressure. Michael |
#164
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Pitch vs. trim in flight phases
On Jun 3, 11:53*pm, Michael wrote:
On May 31, 10:56*am, Tina wrote: The overlooked or ignored difference is if one turns the trim in the wrong direction in a real airplane pressure on the yoke increases. No, this is not universally true. *I've flown airplanes where this is not true, and clearly so has Robert Moore. *These are certificated airplanes ranging from light piston singles to transport category multiengine jets. Hi Michael, Here's my understanding : If the yoke gives force feedback of the out of trim condition (you hold attitude and then trim) then if you turn the trim the wrong while then holding attitude yoke pressure will increase -as Tina says. If it doesn't then you are not holding attitude OR the stick is not connected directly to the elevator surface (e.g. elevator is hydraulic or trim surface powered). I know the latter is the case for big planes (where elevator forces are too large for one armed man power) but what light piston single are you thinking about? Cheers |
#165
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Pitch vs. trim in flight phases
On Jun 3, 4:55*pm, More_Flaps wrote:
Here's my understanding : If the yoke gives force feedback of the out of trim condition (you hold attitude and then trim) then if you turn the trim the wrong while then holding attitude yoke pressure will increase -as Tina says. In theory this is right - but in practice you will have to turn it a long time before the increase is noticeable with certain trim systems. If it doesn't then you are not holding attitude OR the stick is not connected directly to the elevator surface (e.g. elevator is hydraulic or trim surface powered). There is a third option - this is where the trim surface is not connected to the elevator - which is indeed the case. The yoke forces come from the elevator not being 'in trail' with the stabilizer in such a system. Since the angle of the stabilizer changes very little as trim is applied, the force on the yoke in a given position also changes very little. If you move the yoke in the correct direction to maintain the pitch attitude, the force on the yoke will change as it should - but this is also the case in a primitive sim since the stick has a spring return. I know the latter is the case for big planes (where elevator forces are too large for one armed man power) but what light piston single are you thinking about? I'm thinking of the short wing Pipers - the most popular of which was the TriPacer. Michael |
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