trisho0

Trim question for PMDG 737NGX

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1 hour ago, kevinh said:

The only incorrect technique I know of is to fly using the trim. As long as you learn to use the trim to zero elevator control force it’s all good.

Of course. If the stick force is insufficient people wouldn’t be able to trim at all. But higher, more realistic, forces would make trimming much easier.

So, in real...…  trimming is a must but not necessarily with the Logitech joystick right?

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10 minutes ago, trisho0 said:

I think Yoke is not a joystick. Yoke is for real aircraft and joystick is for sim platform. We can trim via Yoke but not via joystick because no pressure is feeling …..so, no need trimming for my birds (lol). I can't afford such sum for a Yoke but at least I learned on it works.

Not at all true. I can trim any aircraft using either Yoke or Joystick if controls are set up and calibrated properly. After I threw out my last yoke years ago, I switched to Joysticks and have never looked back. 

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Posted (edited)
18 minutes ago, trisho0 said:

I think Yoke is not a joystick.

it's exactly the same, looking differently. 

https://www.ataviation.uk/wp-content/uploads/2017/07/IMG_8099.jpg

http://www.tandgflying.com/uploads/3/8/3/7/38378191/_3774146_orig.jpg

https://magazin.lufthansa.com/content/uploads/2016/07/Boeing-737-300-Blick-Cockpit-Teaser.jpg

 

they all do the same: they move steel cables that move the control surfaces, on the last picture via hydraulics, but it's still the same for you as a pilot. Even on the 777 with its fly by wire the feeling of aerodynamical forces is simulated.

https://static.webshopapp.com/shops/122154/files/139023311/900x900x2/ch-products-yoke-usb.jpg

https://hnsfpau.imgix.net/5/images/detailed/33/qq4212.jpg?fit=fill&bg=0FFF&w=1500&h=1200&auto=format,compress

Also the same. exactly the same, just looking differently. there are axes, x and y, y is the elevator axis. it is centered by a spring, as long as you haven't removed it. IF you did this, yes, then you have made trimming completely pointless, but the whole flying experience too. 

 

this thread has become a 5 pages explaination to you what trimming is for and how to do it... If you constantly are ignoring and denying everything that RW pilots and experienced simmers tell you, then those 5 pages are completely obsolete. 

 

edit: 6 pages.

Edited by Ephedrin

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1 hour ago, kevinh said:

The only incorrect technique I know of is to fly using the trim. As long as you learn to use the trim to zero elevator control force it’s all good.

Of course. If the stick force is insufficient people wouldn’t be able to trim at all. But higher, more realistic, forces would make trimming much easier.

The 'correct' technique is to select the desired attitude with the elevator and hold said attitude steady whilst trimming until no remaining pressure is required. The most common error I see is people initially selecting the attitude with the elevator then letting go of the stick whilst trimming, resulting in a rather untidy bobbing up and down of the nose, poor accuracy of flight and quite a bit more time and effort to get the aircraft in trim as it then becomes a guessing game, not least because in between oscillations the pilot has generally forgotten the attitude he was trimming for in the first place. Holding the attitude steady during the trimming process eliminates the guesswork and results in much more accurate flight.

18 minutes ago, trisho0 said:

We can trim via Yoke but not via joystick because no pressure is feeling

Patricio -- are you saying that at any given time when you are hand-flying the aircraft, you just point it where you want it to go, let go and the nose stays exactly where you want it without the need to push forward or pull back on the stick?

If so, you are either flying an Airbus or you are not hand-flying the aeroplane very much!

I urge you to try the exercise I posted a couple of pages back and it will make sense.

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and maybe you should make sure that your realism settings are set according to the intro manual(s). sliders fully right. that's the only thing that comes to my mind that MIGHT (I haven't ever tried it) result in a behaviour like this as, thank god, there is no auto trim "feature" in FSX/P3D.

 

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2 hours ago, Bobsk8 said:

Not at all true. I can trim any aircraft using either Yoke or Joystick if controls are set up and calibrated properly. After I threw out my last yoke years ago, I switched to Joysticks and have never looked back. 

What Joystick brand, model do you have? I can tell my Joystick is Logitech X3D and really I never felt pressure from the stick during takeoff, airborne, landings, etc.

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Posted (edited)
3 hours ago, Ephedrin said:

This is the exact Joystick I have and working perfectly without any kind of modifications. Also, calibrated via Control Panel of Windows 10.

 

3 hours ago, Ephedrin said:

this thread has become a 5 pages explaination to you what trimming is for and how to do it... If you constantly are ignoring and denying everything that RW pilots and experienced simmers tell you, then those 5 pages are completely obsolete.

I stated many times here that I learned how to do trimming thanks to your and from other Pilots help as well. I flew several times and trimming even not feeling any joystick pressure just as a test myself. But, since I don't feel joystick pressure then I don't need to keep trimming my birds.

If you use the joystick as

qq4212.jpg?fit=fill&bg=0FFF&w=1500&h=120

would you do trimming? If so, how do you feel joystick pressure?

Edited by trisho0
correcting

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3 hours ago, skelsey said:

Patricio -- are you saying that at any given time when you are hand-flying the aircraft, you just point it where you want it to go, let go and the nose stays exactly where you want it without the need to push forward or pull back on the stick?

If so, you are either flying an Airbus or you are not hand-flying the aeroplane very much!

Yes, I flew PMDG 737, 747 and 777 trimming only, without push/pull from the joystick until at airborne, stop trimming and AP armed to continue with my flight plan.

3 hours ago, skelsey said:

I urge you to try the exercise I posted a couple of pages back and it will make sense

I did and success but never felt joystick pressure. There is no way to feel pressure I guess because is not powered by design.

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3 minutes ago, trisho0 said:

would you do trimming? If so, how do you feel joystick pressure?

Patricio,

As I've mentioned a few times, I think it is imperative that you sit down and read through the responses here. Granted, it took a bit of a drift for a bit, but the core issue is still discussed.

You will trim in literally every aircraft, with any hardware. It's as much of a fact of flying as moving forward to generate lift. People aren't talking about force feedback, where the hardware generates fake forces to simulate the pressure you'd feel in the real plane. We're talking about having to hold your own pressure on the stick. Unless the stick is sitting perfectly vertical, and you do not need to touch it at all to get the plane to do what you're wanting it to do - climb, descend, fly level - you're putting pressure on it. Any touch, at all - that's the pressure we're referring to. This isn't dependent on the plane or the hardware - it's a simple function of aerodynamics.

Next time you fly, look at the takeoff trim value and set whatever it is +2. So, if the value is 5.6, set your trim to 7.6. After takeoff, I can guarantee that you will have to hold forward pressure on the stick in order to not stall. Doesn't matter if you're flying with an XBOX controller, or a $1000+ yoke. You can then adjust your trim so that you can eventually just take your hand off the yoke and it'll climb properly without a need to hold the yoke (and therefore put pressure on it).

1 minute ago, trisho0 said:

There is no way to feel pressure I guess because is not powered by design.

This doesn't matter. You're confusing concepts. See above...

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2 hours ago, Ephedrin said:

and maybe you should make sure that your realism settings are set according to the intro manual(s). sliders fully right. that's the only thing that comes to my mind that MIGHT (I haven't ever tried it) result in a behaviour like this as, thank god, there is no auto trim "feature" in FSX/P3D.

 

Auto Trim feature? I never saw that Trim settings from any of my sims (fs9, FSX and P3Dv4). I did trimming on all my sims and all of them I get the same results; never feeling joystick pressure.

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12 minutes ago, scandinavian13 said:

People aren't talking about force feedback, where the hardware generates fake forces to simulate the pressure you'd feel in the real plane. We're talking about having to hold your own pressure on the stick.

I understand is clear.

14 minutes ago, scandinavian13 said:

Unless the stick is sitting perfectly vertical, and you do not need to touch it at all to get the plane to do what you're wanting it to do - climb, descend, fly level - you're putting pressure on it.

This is true because before this thread started, I used to fly ILS and AP armed, always. Started this thread is when I learned about trimming.

19 minutes ago, scandinavian13 said:

Any touch, at all - that's the pressure we're referring to. This isn't dependent on the plane or the hardware - it's a simple function of aerodynamics.

Voila! this is what pressure was meant for me, finally.

20 minutes ago, scandinavian13 said:

Next time you fly, look at the takeoff trim value and set whatever it is +2. So, if the value is 5.6, set your trim to 7.6. After takeoff, I can guarantee that you will have to hold forward pressure on the stick in order to not stall. Doesn't matter if you're flying with an XBOX controller, or a $1000+ yoke. You can then adjust your trim so that you can eventually just take your hand off the yoke and it'll climb properly without a need to hold the yoke (and therefore put pressure on it).

I am sure this test will clear me even more.

 

21 minutes ago, scandinavian13 said:

This doesn't matter. You're confusing concepts. See above...

Yes, I was confused about the joystick pressure. I understood. Thanks …. Kyle for your help.

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I flew MHLM rwy04 - MHTG rwy20 frequency=112.30 course 199 with PMDG 737NGX.

It really was a very nice experience trimming all the flight and manual flying. Just hand flying manually until landed. I never armed AP but LNAV and VNAV

I didn't realized in the past I can fly just following the pink line from Navigation Display. A few times using the joystick but definitely at Approach and landed. I need to keep more practicing manual fly again until I get a straight landing on runway (lol). I found trimming is good for manual flying and yes, be able to hands off from joystick but trimming. Several times I got alarm Altitude sound because too much trimming or too low trim so, using the Home/End keyboard often leveling the plane on airborne …… cool! Also, before takeoff I adjusted Trim higher than the FMC CG and while the plane started I heard an alarm sound. I thought about flaps and realized must be the Trim over adjusted. I flew like that to find out needs of trimming. I had to trim down. I could use the joystick instead but keep hands busy.

I think trimming is good feature for manual flights but in real to arm AP is the final step to keep hands off during the flight. Am I wrong again?

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14 hours ago, trisho0 said:

I think trimming is good feature for manual flights but in real to arm AP is the final step to keep hands off during the flight. Am I wrong again?

The thing is that you always want to keep your airplane trimmed properly. Just to neutralize any forces on the controls (yes, not force feedback as Kyle has explained, but any constant action required on the controls). It makes life a lot easier and saver. 

The reason for the autopilot to require a well trimmed airplane to engage is simply that the autopilot may be very accurate, but it isn‘t very fast. You as a human can react instinctively, the AP has to rely on pure data coming from its sensors and gyros. So if you give te controls to the autopilot and they are out of trim it will first have to work against this „problem“ before it can actually fly the airplane. And that‘s just too much for the system. So male sure that you are comfortable with the controls, that your stick is centered and the airplane‘s nose doesn‘t move and then give it to the AP. Then everything is fine.

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56 minutes ago, Ephedrin said:

The thing is that you always want to keep your airplane trimmed properly. Just to neutralize any forces on the controls (yes, not force feedback as Kyle has explained, but any constant action required on the controls). It makes life a lot easier and saver. 

The reason for the autopilot to require a well trimmed airplane to engage is simply that the autopilot may be very accurate, but it isn‘t very fast. You as a human can react instinctively, the AP has to rely on pure data coming from its sensors and gyros. So if you give te controls to the autopilot and they are out of trim it will first have to work against this „problem“ before it can actually fly the airplane. And that‘s just too much for the system. So male sure that you are comfortable with the controls, that your stick is centered and the airplane‘s nose doesn‘t move and then give it to the AP. Then everything is fine.

Yeah! thanks for more details. But, why do you say "well trimmed"? I flew again this time with ILS approach. So, I did take-off the plane and right on airborne I left the joystick alone and trimming nicely on PMDG 737NGX. Once I reached the programmed Altitude simply I armed AP and kept flying. Now trimming works for me ….finally!

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1 hour ago, trisho0 said:

But, why do you say "well trimmed"?

Trim can be way off, a little off or right on.  Anything close to right on could be called well trimmed.

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Posted (edited)
48 minutes ago, downscc said:

Trim can be way off, a little off or right on.  Anything close to right on could be called well trimmed.

How far can be trim way off? Visible from somewhere? From the trim wheel? Or, just looking outside of the plane thru cockpit cabin watching the nose position?

Edited by trisho0
details

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Just now, trisho0 said:

How far can be trim way off? Visible from somewhere? From the trim wheel? Or, just looking outside of the plane thru cockpit cabin?

I'm still not sure you're getting this (and in fairness it is difficult doing this in text!).

It is about how the aeroplane feels. Let's say you want the nose to be pitched 5 degrees above the horizon. Are you having to hold the stick way back to keep it there? If you release the stick even a little bit does the nose immediately want to drop quickly?

Then the aeroplane is not in trim (and indeed is a long way out of trim). Lots of movement of the trim wheel is necessary to put the aeroplane back in trim.

However, if you only have to hold the stick very gently back to maintain the pitch attitude you want then the aeroplane is very nearly in trim and only a small adjustment may be necessary.

(Of course, you could equally be having to hold the stick forward - the same principle applies).

If you would like to, I would be happy to spend an hour or so with you using the free JoinFS shared cockpit software we use for our training courses at BAV to teach you practically how to trim, which is probably a lot quicker and easier than trying to describe things in text  (on both sides of the conversation!) - just drop me a private message via the forum and we can get something set up (probably next week).

Best,

Simon

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I can't believe the length of this thread to explain trim which any student pilot learns in the first hour of dual instruction. You get the aircraft in the attitude you want, and at that  point you are most likely pulling or pushing on the elevator control . Then you move the trim, so that the amount of pushing or pulling goes to zero, and you can take your hand off the elevator, with no change in the pitch. That's it.. Nothing more. 

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On ‎6‎/‎21‎/‎2018 at 8:02 PM, Bobsk8 said:

I can't believe the length of this thread to explain trim which any student pilot learns in the first hour of dual instruction. You get the aircraft in the attitude you want, and at that  point you are most likely pulling or pushing on the elevator control . Then you move the trim, so that the amount of pushing or pulling goes to zero, and you can take your hand off the elevator, with no change in the pitch. That's it.. Nothing more. 

Yes, this is clear to me definitely. I meant, finally is clear for me and thanks for all of you Pilots and Support.

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On ‎6‎/‎21‎/‎2018 at 5:27 PM, skelsey said:

It is about how the aeroplane feels. Let's say you want the nose to be pitched 5 degrees above the horizon. Are you having to hold the stick way back to keep it there? If you release the stick even a little bit does the nose immediately want to drop quickly?

I don't have to hold the joystick on this case. If I release the stick the plane nose goes down quickly. I do trimming to pitch attitude and at the same time I can release gear hydraulics, Autobrake system Off and moving flaps up accordingly following the PFD. Now, no more trimming and arm AP.

On ‎6‎/‎21‎/‎2018 at 5:27 PM, skelsey said:

If you would like to, I would be happy to spend an hour or so with you using the free JoinFS shared cockpit software we use for our training courses at BAV to teach you practically how to trim, which is probably a lot quicker and easier than trying to describe things in text  (on both sides of the conversation!) - just drop me a private message via the forum and we can get something set up (probably next week).

I visited JoinFS site and I am new on that. I am not ready for JoinFS until I can afford it. Thanks so much for your great help as well. I think I understood about trimming anyway. Just to practice trimming with my birds. I am flying several times same route from MHLM rwy04 to MHTG rwy20 and manual landings. (No ILS available). Since the flight is very short time I am getting more experience with trimming and manual landings.

 

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15 hours ago, trisho0 said:

I don't have to hold the joystick on this case. If I release the stick the plane nose goes down quickly. I do trimming to pitch attitude and at the same time I ...

Hmm. The nose shouldn’t go down quickly. You should have the plane trimmed so that you can release the stick and the nose stays where it was. 

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22 hours ago, trisho0 said:

Since the flight is very short time I am getting more experience with trimming and manual landings.

The trimming is explained even more from 

and easy to understand.

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6 hours ago, Spin737 said:

Hmm. The nose shouldn’t go down quickly. You should have the plane trimmed so that you can release the stick and the nose stays where it was. 

Yes, not too quickly I know but it goes down if not trimming until the plane becomes balanced on airborne.

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Posted (edited)
On 6/20/2018 at 10:29 PM, skelsey said:

The 'correct' technique is to select the desired attitude with the elevator and hold said attitude steady whilst trimming until no remaining pressure is required.

You can trim just as correctly by holding airspeed with elevator. Pitch and airspeed are inextricably linked for a given flight path and the chances are the pitch you selected to trim at was governed by the airspeed you want to fly at. 

Generally speaking small changes in attitude cause larger changes in airspeed and vice versa. So holding airspeed is likely to be more precise than holding attitude. Especially with a PFD and a speed trend vector. Even more so at higher speeds, where pitch hardly varies.

 

Edited by kevinh

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8 hours ago, kevinh said:

You can trim just as correctly by holding airspeed with elevator. Pitch and airspeed are inextricably linked for a given flight path and the chances are the pitch you selected to trim at was governed by the airspeed you want to fly at. 

Generally speaking small changes in attitude cause larger changes in airspeed and vice versa. So holding airspeed is likely to be more precise than holding attitude. Especially with a PFD and a speed trend vector. Even more so at higher speeds, where pitch hardly varies.

As I said to Andrew -- if it works for you then that's fine, however:

  • The primary effect of elevator is pitch
  • We trim to relieve pressure on the controls
  • We select a pitch attitude (and power setting) in order to produce a desired airspeed/performance (climb/descent at a given airspeed or straight and level etc).

Thus we are trimming for a pitch attitude, which we have selected using the elevator in combination with a power setting in order to achieve a particular airspeed/and or performance. One does not 'hold airspeed with elevator' -- one holds a pitch attitude, which in combination with a particular power setting will result in a particular airspeed.

If the aircraft is not trimmed then the pitch attitude will deviate from that which we had selected and the airspeed will also change. The airspeed changes because the pitch attitude has changed. To regain the desired airspeed we then use the elevator to re-select the associated attitude, and trim to relieve the control pressure.

If we subsequently change the power setting then the nose will indeed rise or fall, but I can't think of any practical situation where one would be altering power without also wanting to also positively change the attitude -- either to commence a climb or descent, or to maintain straight and level flight at a different airspeed.

As an experienced pilot you probably know the approximate pitch attitudes/change in pitch attitude required for given airspeeds etc for a particular type and so the process is very natural. As I mentioned earlier, however, there are a couple of issues with this approach, especially when applied to inexperienced pilots.

The airspeed indicator (as with all the instruments) is subject to a certain amount of lag; the inertia of even a small aeroplane means that there will naturally be a delay between the attitude being selected and the response on the airspeed indicator. If an inexperienced pilot is being told to pitch with primary reference to the ASI or other instruments (VSI/altimeter) the almost universal result is significant overcontrolling and quite unstable flight as they chase the needles around -- I've seen it! Once the student starts looking either out the window at the visible horizon at a basic level, or the artificial horizon at a more advanced level, and starts focusing primarily on the pitch attitude their flying invariably becomes much smoother and more accurate. They also get to know the pitch attitudes and power settings associated with different airspeeds.

On a similar note the lag associated with the pressure-operated instruments means that by the time the pitch attitude has changed sufficiently for a change in airspeed to occur, chances are that quite a large change in attitude has occurred. Again, the result of this is invariably overcontrolling. Indeed, this is why limited panel instrument flying is such a challenging skill and why when one starts to fly on instruments the teaching tends to shift to 'throttle controls airspeed/pitch controls rate of descent' -- it is much more practical when flying an ILS, for instance, to point the aeroplane toward the needles and maintain speed with power!

Changing airspeed does require a trim change, but (if we are talking about maintaining steady-state flight, whether straight and level or a steady climb or descent) this is because an attitude change is required to maintain the steady state (Lift = AoA x Airspeed). If you increase airspeed in level flight, you will have to use the elevator to lower the nose if you are to maintain altitude. This lower nose attitude requires, clearly, a change in trim to relieve the control pressure that would otherwise be required to hold the nose in the new attitude. The change in trim, however, is to maintain a different nose attitude, not simply because the airspeed has increased. To suggest that the trim needs to be changed because the airspeed has changed is rather the tail wagging the dog: it skates over the very important point that a new pitch attitude is required at the higher airspeed.

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