Simviation Forums

I purchased FSX about 2 weeks ago.  After huge problems with the product key, I FINALLY got the darn thing installed about 3 days ago.  I started going through the lessons and missions and pretty much figured out that while I can finish the first 5 tutorial missions rather easily, I really don't know what I'm doing.

So I decided to go into the lessons where you have the instructor (Rod?) telling you what to do.  Well, I'm on lesson 3 and I'm completely stuck.  Basically, I have absolutely no grasp of what "trim" is.  The lesson is telling me to climb from 4,000 feet to 5,000 feet by using:

First:  Attitude
Second:  Throttle
Third:  Trim

Ok, well I get the attitude and the reason for going full throttle, but then I have absolutely no clue what to do with the trim.  I thought that the trim kind of evened out the plane so that when I'm climbing with the stick pulled back, adjusting the trim upwould allow me to keep climbing while putting my stick back to the neutral position.  

If, in fact, that is the right definition then it's certainly not working.  Or I just do not know how to realize when the trim is enough.

Am i completely wrong?  I get confused because the instructor seems to allude that the trim has something to do with airspeed as well, as he says to adjust the trim when it gets to 75 knots, and that adjusting trim will make the plane stay at 75 knots like an auto-pilot.

ANY help would be appreciated.  I'm on AIM at JetsMets77 if anyone wants to chat.  I hope that I can lean to fly these darn planes and be a part of this community which I've been lurking at for 2 weeks now!

Thanks in advance.

Have you tried to take the lessons? They are a real help to new learners.

There's an old joke... "How long does it take to trim a Cessna172 ?

Got to raise my hands to applaud Brett.  He`s one of the most knowledgeable in this subject and will not just rush through it to get the answer over with.  If he doesn`t know, he will find out.  You`ve dropped lucky Rude, very lucky there. Nice to see this.

Reider

PLUS......you gotta know where your trim buttons are on the joystick ( i hope you're using a joystick!)

Thanks for the help,  I definitely need to keep practicing and hopefully it will just start to make sense.  I am using the Saitek 52 Flight Control system and set my 2 buttons to trim up/down.

Brett, something in your post kinda just clicked in my brain, so I'm going to play around for an hour or so and see if I can get this down.

One stupid question...when climbing am I supposed to trim up or down?

The idea of trim is to reduce stick or yoke loads to reduce pilot fatigue.

You should be able to just let go of the Stick/Yoke once you are trimmed properly and the attitude should remain constant (or nearly so).

Set the buttons/controls up where they are handy, ( I use the top right buttons on my joystick), because you'll find that trim is used extensively once you learn to fly.

Rudder trim can be used the same way to offset yaw creeping under different power settings.

Trim as required, up or down, nose up attitudes will require positive trim etc. Both power and attitude adjustments will throw the trim off, that's why you trim last when adjustments are made. Also, if the plane is accelerating or decelerating, the trim will alter.

Here is a noob trick...... Trim the same way you fly, in other words, back trim corresponds to back stick, up is up , down is down, don't reverse the trim from the primary flight controls.

After a while, you'll find that you are flying with trim as much or more than your primary controls, it's much easier to make small adjustments in trim than to fly with the primary controls and then trim for balance. This depends a lot on aircraft type. Larger aircraft (in general) are more easily handled with trim. In fact, elevator trim becomes the larger force on the big jets, load up one into the sim, go to

Well i went back into the lesson and passed it first try.  I definitely understand trim (I actually pretty much had it correct before) but now I understand the order and timing of applying trim.

One thing I do not yet grasp is knowing when I've applied enough trim.

The trim is correct when you can release the controls and the plane remains stable. Therein lies the essence of trim.

Edit:
About 20 hours to trim a cessna is not a far fetched estimate, it requires practice as stated before.

[quote]Well i went back into the lesson and passed it first try.

[quote][quote]Well i went back into the lesson and passed it first try.

I'm still a newb at these forums, but my experience is that trim, especially in the flight sim, is extremely difficult to master. I always hear "Don't fly the plane with trim, fly with the yoke, then release the back pressure with the trim." But still, I have a bad habit of trimming to change VS -- I know this is bad!

About 5 years ago, I started flight lessons and had only 12 hours of flight time before I had to quit for reasons not important, but one thing I do remember is that trimming a real cessna is much easier than the sim. My computer yoke, for instance, has about 1/2" space around which it will remain stationary, meaning that I could nudge it a bit, and it will stay that way, but of course have drastic effects in the sim.

This problem coupled with no 'fine-tuning' trimming wheel make it especially difficult. Well, off to practice some more!

here's what typically happens.  I pitch to the proper angle, go full throttle and I can get it stable fairly easily at 75 k.  So I start to apply trim.  Then I release the yoke a bit to see if the trim will keep it at the rate of climb that I want.  But it doesnt stay steady. The plane drops because I didn't add enough trim.  Because the plane drops, the airspeed increases and now I'm back where I started.  Basically, I have no idea when to stop trimming up.

Am I supposed to be releasing the yoke at the same time that I apply trim?  Or do you apply the trim and then release the yoke?  Do you release it steadily or just let it go back to default all at once?

I dug out an old joystick  (Logitech 3D Pro) so we could be on the same page.

I forgot how much different (more difficult) it is... But the theory is the same.

One thing though, that's more important with a joystick; is to be trimmed for takeoff before taking off. You use the trim gauge as reference, so that you can confirm takeoff trim as part of your pre-takeoff checklist. I'll run the sim after posting this, and return with some screenshots.

If trimmed for takeoff, it doesn't take much back pressure at all to rotate and start climbing.. consequently, it doesn't take much trim change to trim for climb... and after some practice, you'll nail it pretty quickly.

Now is a good time to ask how you have trim set up. On the CH yoke, it's near ideal. A little rocker switch for your left thumb so that you can work the yoke, handle the throttle and trim, all at once. If you have trim set to a pair of butttons, that you have to consciously stop and reach for.. trimming with a joystick can be quite a chore. On the Logitech that I have.. trim is set to buttons 3 & 4, which are convenient for the thumb of the hand holding the joystick (I think that's even the default setting). A little back pressure and then a little up trim and you're all set.

Anyway.. you've got the right idea. As you're holding back pressure, you hold the "trim-up" button until the nose starts pitching up even a little more than the back pressure that you're holding causes.. then immediately switch to "trim-down".. kinda releasing joystick pressure a little to see what happens as you're now trimming up and down for a few seconds, getting the feel for it. After some practice, it'll become second nature. You'll apply takeoff power, rotate at 60kias, instinctively trim it pretty darn close. Although I've mentioned to NOT "fly by trim", you almost have to (just a little) with a joystick. They aren't as subtle and precise as a yoke.

Brett,

The CH flight yoke is the one I have. For the longest time, I used the wheel on the left thinking that was trim. I realize now that that's not connected to the computer at all, but its a tuning for the flight yoke itself!

Now I do have it mapped to the rocker under the left thumb.

On a similar note, I was flying the Airbus A321 last night, and noticed that the trim didn't seem to work at ALL. I could hold trim down one way or the other indefinitely, and nothing happened. Is there something I'm missing there?