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Dragonmount

Trim setting question

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I've been learning to fly the carenado PA46T, and have been enjoying it, part of that reason is, that it actually has some sort of way I can see where the trim setting is. On other aircraft, is there anything that can help me with some sort of number I can shoot for when I fly? For instance the sweet spot on the PA46T seems to be about -5.8 (not entirely sure what that means, but thats about the number on the trim setting that seems to keep the plane from going too far up or down.On the FSX aircraft that have GA trim, again my question is: How do I know what my trim is? Is it just messing with the trim while in the air till you get it? Every time?

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Trim is used to remove control forces...

 

E.g. you set the pitch you want with the yoke / stick... then remove whatever force is being applied with trim.  You should be able to look outside and know whether you are level, climbing or descending w/o looking at any pitch instrument.  I have a button under my right thumb on the stick which allow me to quickly apply forward / aft trim.

 

So yes... it is "just messing with the trim" until you get it.  Set the pitch with the stick, remove the force applied with trim.

 

The only time I am specifically concerned with the actual trim setting is takeoff.  With certain aircraft (e.g. the MS DH.88 Comet)... if pitch trim is set outside a certain range, the takeoff run is longer / stick forces are "excessive" etc...

 

You can make a sub-panel and use the trim gauge from the FSX Mooney... that is what I did for the Comet.

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Now im not a real pilot get but from what I have witnessed IRL and from flight simming is that there is no default trim setting. It will all depend on weight, air density, atmospheric conditions, speed, aerodynamics and altitude.

 

The trim settings will be different during climb out, cruise, and descent and will vary according to the factors above. From what I understand some planes need less trim at lower speeds, while other have need more.

 

So I guess to answer your,question, there is no magic number. It will all depend on the situation.

 

Just to add, I use airhauler and ideal flight 10 so I have to watch my take off climb to avoid penalties, so I keep my climb rate under 12degrees and set my trim to my mouse wheel for easy manipulation.

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I used to use a little addon called "RealTrim" that worked a treat.  You'd use it just like mentioned above, set your desired pitch with your yoke / stick, push a button and then you could release the pressure on your yoke.   However, I sprung for a Saitek trim wheel awhile back and I love the thing.  Makes trimming for either level flight so painless.

 

As far as your actual question goes, both of the above responses answered it well.  In flight, there's no 'ideal' trim setting.  I usually pick a speed that I want to maintain, and work both throttle and trim until I hit level flight at that speed.

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It will all depend on weight, air density, atmospheric conditions, speed, aerodynamics and altitude.
 

 

This may be true... but as a pilot (or an instructor) I don't concern myself with all that.
 
I care about one thing... removing the force that I am having to apply to the control column for my current pitch I am holding... I do that with trim.
 
No worrying about speeds... or this... or that... just what force am I applying... I use trim to remove that force so I can go "hands off".
 
You mention you have to keep your pitch below 12° (please see my Vy / pitch discussion below)... good you use something to trim with easy (mouse wheel).  My Saitek 65-F has a switch on the right stick under my right thumb.  Easy to apply forward or aft trim... whatever needed to zero out the force on the stick.
 
 

I usually pick a speed that I want to maintain, and work both throttle and trim until I hit level flight at that speed.
 

That seems like a lot of work.  If you like it - ok good as we do what we like and enjoy - not here to "convert" you and certainly not to criticize... but please allow me to explain another way.

 
Check out the pic of the C152 in a Vy (Best Rate of Climb).  This all goes back to the basic Pitch + Power = Performance.
 
When I pitch the nose of the 152 up to where the dash above airspeed indicator is slightly below the Horizon (see the pic) and with full power, I know I will get 67KIAS (Vy) every time.  Depending how you have your Eyepoint set, it may look a little different.  However you can still establish some sort of reference with your plane... Just as I established what a Vy climb looks like to me... no looking at the Airspeed Indicator (again) or any other pitch instruments.
 
Pitch the nose up to where I want it (Dagger... you could do the same thing except know what 12° looks like i.e. the Horizon / Dash and know that is "Max Pitch") ...pitch the nose up to where I want it and trim off the Aft stick I am holding.
 
Same thing for Level Flight... know what my "Sight-picture" looks like... In my case it looks like an inch or so between the top of the Dash and the Horizon.  IRL it might be you could put your fist up on the dash, or e.g. three fingers between the top of the Dash and the Horizon... whatever it is for you - that is what you memorize.
 
Ok back to Jimmy's trimming... here's how IRL.
 
You go to the Performance Charts and pick a Percent Power... let's say you decide on 65% Power.  I found a pic of a Seneca Power Setting chart... so if flying the Seneca e.g. let's say temp and pressure are close to Standard Day.  It's a short hop and you decide on 4,000'MSL.
 
Go to the Chart (see pic)... at 4,000' let's say you don't want to hear the props scream, so you decide on 2100RPM... means you will need 24.8" of MAP (Manifold Pressure) to achieve 65% Power.  Now you can go to the other charts and determine what your Fuel Flow (Extremely Important) will be and the approximate Airspeed your will achieve.
 
You takeoff... got your Climbout Pitch established with a certain Max Allowable Power setting giving you a certain Performance (a certain Airspeed and Vertical Speed)... trimmed out.
 
Just as you start to approach your desired altitude, you lower the nose (forward pressure) to your "cruise sight picture" and trim, trim, trim, trim getting that forward pressure you are applying off - as Airspeed builds close to your expected Airspeed.  Then MAP comes back a couple of Inches below your desired Setting... Prop back to 2100 - then adjust (usually bump up) the Throttle till your MAP is at that desired 24.8".
 
As Airspeed stablizes (you should be very close since you know what it should be) you bleep off whatever remaining stick force(s) there are.
 
Most (a very high percent) of the time, Eyes can be kept Outside, because you only need an occasional glances back to the panel to tweak settings.
 
So... level the plane - set the power - and trim out as airspeed stabilizes.
 
-------------------------
 
If you are holding any stick forces then you aren't trimmed out.  Simple as that.
 
There may be good reason for not trimming out and as a result, holding a certain stick force... Landing is one example... you might (not a good idea) trim out so much to hit your over the fence speed w/o much force on the stick... then a Go-Around happens to become necessary... now you find yourself in a world of hurt because you have applied Full Power and with all that Aft trim applied on final, the nose is now pitching up "way high" -  you're now fighting to push the stick forward - and you may be finding yourself in a Takeoff / Departure Stall very close to the ground.
 
But typically... during Climb, Descent, Enroute... make it easy on yourself and trim out those stick forces for the pitch / power you have set.

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Vy for me is 81 KIAS. I take off, pitch to 81 knots. I then trim until the plane maintains 81 knots with no pressure on the yoke. That's it!

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Vy for me is 81 KIAS. I take off, pitch to 81 knots. I then trim until the plane maintains 81 knots with no pressure on the yoke. That's it!

 

Precisely (for most of my flying, a Vx pitch hasn't been necessary).

 

And (as I am sure you know / and do) you can do that right after takeoff w/ reference to the (outside) horizon (unless going IMC of course).

 

Fwiw, the Vy pic was just something I had handy... couldn't find my (similar) example pics of cruise and descent.

 

-Rob

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but please allow me to explain another way.

 

And you've explained it very well indeed!  I'm not a r/l pilot, and although I've read much on the basics of flying, I lack a lot of the 'vocabulary' used in describing your usage of trim so eloquently.  I do probably 75% of what you've described already, I just didn't explain it well (at all!) or go into any detail about holding the plane level and at the power setting I desire and then trimming to remove the requirement to hold pressure on the yoke.  I would of been much better off simply to stick with how much I enjoy using my Saitek trim wheel to achieve this. :lol:

 

The on thing you note that I'm *very* guilty of in FS, is about using trim for landing.  I almost always use trim at least a little bit to avoid minor corrections with the yoke.  However, this is primarily because my Saitek yoke is getting a bit 'jumpy' near center - it has a slight tendency to stick just a bit, which results in over corrections.  At least it's something that I can use without worry in a simulated setting!

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A lot of people use a little nose up trim on landing to help keep the nose up as you decelerate down the runway (both to avoid a prop strike and for aerodynamic braking).

 

I think I have a video somewhere of a short field takeoff where I trim to Vx, then level out, raise the flaps, and go to Vy. Look up my YouTube account: N8229Y

 

It's there somewhere.

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And you've explained it very well indeed!
 
Thanks Jim,
 
I appreciate you taking the time to say so... 
 
 

At least it's something that I can use without worry in a simulated setting!
 
Yep... whatever works here.   B)
 
 

The on thing you note that I'm *very* guilty of in FS, is about using trim for landing.
 
In Flight Sim I really see nothing wrong with it... it's just one of those things to be aware of - particularly for anyone taking something from the Sim to RW application.
 
I like to trim out for my final approach speed and then leave it there.
 
VERY important to be "On Airspeed" during Final (and trim can be very useful here).  Take a RW example with the Warrior II.  63KIAS is what is typically used for final in the pattern.  63KIAS is also Gr. Wt Vx (decreases with decreasing weight) but Vy is 79KIAS.  So the faster you are during climbout (if a go-around) the quicker your hand is going to have to work rolling that trim wheel forward.
 
 

A lot of people use a little nose up trim on landing to help keep the nose up as you decelerate down the runway (both to avoid a prop strike and for aerodynamic braking).
 
This is where my primary instructor always "rode me" to keep the control wheel in my lap.    :wink:   (It wasn't easy.)

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This is where my primary instructor always "rode me" to keep the control wheel in my lap. :wink: (It wasn't easy.)

 

Yes indeed. And I had trouble getting used to the idea of pulling the yoke all the way back, too!! I keep 50 pounds of weights in the luggage compartment of the plane when I fly with no rear passengers to help balance things out and assist me in keeping the nose up with less force on the yoke. The IO-360 is a heavy engine!!

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