It sounds quite useful for a helicopter sim though, as that's more like how trim works in that case.

Please correct me if I am wrong, other than few hi tech military heli's, helicopters do not have trim. Dodosim added an option to there Jetranger as pilots were getting sore arms on long flights, I don't think this is realistic too. The Russian Kamov KA 50 had a hold and click trim.

I don't know about FSX or Prepar3d, but FS9 only models yaw trim in  helicopters. And the key commands for it are a little different than for fixed wing bird. To wit: instead of ctrl+keypad ENTER or 0, it's just Keypad Enter or 0, no more ctrl key. I know I've read up on it. HTRv1.5, however, will model trim in all 3 axes if the bird is set up for it. Since I almost never fly a chopper without HTR running, well...but it is really only for things like the HH-60, and so on, the advanced military birds.

Don't know if that helps or not...

Pat☺

Please correct me if I am wrong, other than few hi tech military heli's, helicopters do not have trim. Dodosim added an option to there Jetranger as pilots were getting sore arms on long flights, I don't think this is realistic too. The Russian Kamov KA 50 had a hold and click trim.

Most, if not all, helicopters with power controls have trim release systems. These mean that the controls stay in the position you released them in. Dodosim were replicating reality with their 206 trim system, given the limitations of sim joysticks.

RealTrim is realistic in the sense that it lets you trim the plane while smoothly returning a spring loaded yoke to it's neutral, no force position. This simulates adjusting RW trim so there is no force on the yoke. I find this better approximates my RW experience then repeated "guessing" on how much trim to input since there is no force feedback provided as in the RW. With RealTrim you can still make minor trim inputs as you would do without RealTrim. As you said, to each his own.

Al

There's nothing in the real aircraft which does what realtrim does. There is force feedback in FSX but it is less than in real life, being the spring in your control input. I don't find trimming in full fight sims any easier than in FSX. The guesswork is still there. Realtrim essentially trims for you at the press of a button. So all skill is removed.

There's nothing in the real aircraft which does what realtrim does. There is force feedback in FSX but it is less than in real life, being the spring in your control input. I don't find trimming in full fight sims any easier than in FSX. The guesswork is still there. Realtrim essentially trims for you at the press of a button. So all skill is removed.

I have to disagree somewhat. With RealTrim you push and hold a button on the yoke and return the yoke to it's no force position. In a RW a/c with electric trim, like a Mooney Bravo, you again push and hold a button on the yoke until you feel no force on the yoke.  So in both cases you trim by "pushing a button" until "no yoke force", and then will likely have to "touchup" the trim a bit. Due to the "play" in most spring loaded yokes, RealTrim is most useful for significant trim changes (doesn't work well for minor adjustments), and only gets you "close". You still have to make small adjustments with the trim button as you realistically would.

 

That's my perception, but I've not flown a plane with electric trim in the RW, but rather either turned an overhead crank (Piper Cherokee) or a trim wheel (C172). In those planes, in addition to the force feedback cues, you quickly learn about how much trim input (e.g, one turn of the crank or wheel, etc) will get you close for typical trim change situations like after leveling off after takeoff. My point is that in my limited RW experience there typically is not a great deal of skill required to get the trim "close".

 

However, I have no idea how difficult it is to hand trim an a/c like the 737 in the RW, and for that matter, wonder how often the plane is actually trimmed by hand. If the autopilot is engaged at less than a 1000 ft AGL after takeoff, and remains in control until about minimums on approach, I would guess little hand trimming is required (perhaps a 737 pilot will provide some input on this).

 

When I took up simming about a year ago, the contrast between trimming in the RW and in the sim was what bothered me the most. I stumbled on RealTrim and for me it makes sim flying more realistic and enjoyable. Clearly that is not the case for everyone, and that's fine.  The good thing is RealTrim is freeware, so if someone hasen't tried it they can give it a shot at no cost, and then delete it if they don't like it. Remember, it doesn't work with the 737NGX (as I recall, it does work with the FSX default 737). If interested, RealTrim17X is available here: http://code.google.com/p/fscode/downloads/detail?name=RealTrim17X.zip&can=2&q=

 

Al

 

 

I have to disagree somewhat. With RealTrim you push and hold a button on the yoke and return the yoke to it's no force position. In a RW a/c with electric trim, like a Mooney Bravo, you again push and hold a button on the yoke until you feel no force on the yoke.

Put like that, I accept your point with respect to manual flight controls. In that case the elevator deflection doesn't change, the trim tab moves to apply a balancing hinge moment, reducing the force to zero at which point you are in trim. But it's different with fully powered controls where the trim is moving the stabiliser. The zero force position doesn't move much (if at all) with trim (depending on the design) and so holding the column in position and trimming out the force won't work. Realtrim exactly replicates what happens in this case but removes all the skill necessary.

 

As realtrim doesn't work in the NGX it's a moot point. The only way to get used to trimming it is to fly with AP off and practice.

So, the general rule of thumb is:

Establish yourself in the condition you want to be in (e.g. a climb at 250 knots, pitching to maintain that speed), and then trim to the point where you don't need to put any pressure on the yoke (and yes, it will return to the neutral position when you do this).

 

 

But it's different with fully powered controls where the trim is moving the stabiliser. The zero force position doesn't move much (if at all) with trim (depending on the design) and so holding the column in position and trimming out the force won't work.

 

 I feel like the more I learn about the 737NGX the less I know.  :huh:

 

I don't know how to reconcile the above statements.  And if in fact you can't use pressure feedback to trim, what is the recommended technique for trimming the 737 (a question which gets us back to the original point of this thread -- I apologize for the RealTrim digression)?

 

Al

 

Edit: There is an interesting and germane discussion on 737 trim on the Airliners Tech/Op forum, just do a Google search for 737 Trim and Yoke Center Position,  and more info on the Boeing 737 Tech Site here:  http://www.b737.org.uk/flightcontrols.htm , click on Stab Trim.

Actually, you do not get to feel the real force on the controls, force caused by air pressure on the flight surfaces. But you do get to feel the force on your controls caused by the springs in your joystick or yoke. So while holding back your joystick, let's say, start trimming nose up and gradually release the pressure on the stick until it sits in the center. Then do fine adjustments.

 

I find you trim a lot more in a sim than in a real airplane. In the real thing the area in which you can comfortably hold the yoke is much bigger than with a joystick or yoke on your computer, where the springs kick in as soon as you move away from center.

I don't know how to reconcile the above statements. And if in fact you can't use pressure feedback to trim, what is the recommended technique for trimming the 737 (a question which gets us back to the original point of this thread -- I apologize for the RealTrim digression)?

No worries about the RealTrim digression, it made me think a bit more about the subject too.

 

I don't see any contradiction between Kyle's post and mine. My understanding of what he wrote is that you apply some trim and move your control at the same time to maintain the desired flight condition. Trim a bit more, move the control a bit more, etc. Eventually you are at the zero force position of your joystick and the aircraft is in trim. That's pretty much how it works in the real 737, though the neutral position will move a little in the real aircraft according to stabiliser position, as Matt pointed out.

 

The 737 technical site is an excellent resource of accurate and practical information. That a.net thread pretty much mirrors this one, highlighting the difference between aircraft trimmed by moving tabs and those trimmed by moving the stabiliser.

This has been an interesting and informative discussion, at least for me. As a result of this thread, and the info at the sites I pointed to above, I think I now understand the major differences between trimming a light GA a/c and an airliner like the 737.

In the GA case, you move the yoke from its original position to obtain the desired a/c response, and then add some trim, if pressure remains on the yoke you add more trim and so on ( an iterative process) until there is no pressure on the yoke. The yoke has not moved during trimming and so ends up in a new "no pressure" position.

 In something like the 737, you again move the yoke from its original position to obtain the desired a/c response, but now as you add some trim you let the yoke move back a bit towards its original "no pressure" position, if there is still pressure on the yoke you add more trim as you continue to let it return to its original position, etc  (again an iterative process but in practice I would think a fairly fluid process). So, unlike the GA case, the yoke ends up back in its original position when the a/c is in trim.

 In both cases, however, I see it as a force feedback process that involves the pilot sensing yoke pressure (or force) and adding trim until the pressure on the yoke is relieved.  It is ironic that the simple spring loaded simulator yoke, and how RealTrim works, seems to model the airliner trim process better than it does the GA one.

Al

I'll get back to one point I think that might be a bit of an issue in confusing the OP.

 

 

 

Besides when I watch video of B737 NG, PF barely trims the aircraft and doesn't need to give lots of correftion in order to maintain the desired flight path.

 

In the 737, trim is normally done by on-yoke switches. You might not notice the pilot using them, since short pulses normally don't activate the clacker. You'd have to watch for small trimwheel movements.

IMHO, Ark pretty much summed it up about as well as one can...

Just my opinion though.

 

Pat☺

Hi all,

 

Just to add my 2 cents, I use realtrim v1.7 for FSX, and it works perfectly with the NGX. I am using a Saitek Cyborg evo joystick, I have assigned 1 button to realtrim and it makes trimming a breeze : when pressure is applied to the joystick to adjust pitch, I then just push the assigned button while releasing the joystick back to neutral and it's perfectly trimmed.

 

Personally I find this pretty realistic, at least compared to my own experience flying a real light aircraft. In real life you know when you're trimmed because you feel the pressure disappearing in the hand holding the yoke while you trim with the other hand (I flew a Robin DR400, I'm French too...). To me, realtrim reproduces that feeling pretty well...

Hi all,

 

Just to add my 2 cents, I use realtrim v1.7 for FSX, and it works perfectly with the NGX. I am using a Saitek Cyborg evo joystick, I have assigned 1 button to realtrim and it makes trimming a breeze : when pressure is applied to the joystick to adjust pitch, I then just push the assigned button while releasing the joystick back to neutral and it's perfectly trimmed.

 

Personally I find this pretty realistic, at least compared to my own experience flying a real light aircraft. In real life you know when you're trimmed because you feel the pressure disappearing in the hand holding the yoke while you trim with the other hand (I flew a Robin DR400, I'm French too...). To me, realtrim reproduces that feeling pretty well...

But as was discussed at length in this thread the 737 is not a light aircraft and is not trimmed by holding the yoke still while moving elevator trim tabs to reduce control force to zero.

 

So RealTrim for the 737, or any other plane that uses stabiliser trim, is basically an aid which removes the necessary flying skill. It's like always using autoland. I understand why it's useful for FSX aircraft that use elevator trim.

Hi all,

 

Just to add my 2 cents, I use realtrim v1.7 for FSX, and it works perfectly with the NGX. I am using a Saitek Cyborg evo joystick, I have assigned 1 button to realtrim and it makes trimming a breeze : when pressure is applied to the joystick to adjust pitch, I then just push the assigned button while releasing the joystick back to neutral and it's perfectly trimmed.

 

 

That's interesting; I have not been able to get RealTrim1.7 for FSX to work with the PMDG 737NGX, although it does work with all the FSX default a/c that I have tried including the 737-800. Did you have to do anything "special" to get RealTrim to work with the 737NGX? Similar to your joystick setup, I use a button on my Saitek yoke to activate RealTrim.

Thx,

Al

I have not done anything special, I had ReamTrim 1.7 module installed prior to installing PMDG 737 NGX and it worked right at first install.

 

Dońt know what could explain the difference...