Trim Takeoff Setting

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Oracle427
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Re: Trim Takeoff Setting

Post by Oracle427 »

A 172 does not have rudder trim so that will be of no help. You should not be attempting to control the aircraft with trim.

Are you applying right rudder to maintain directional contol? It is perfectly normal for a prop aircraft to turn left due to left turning tendencies that are most prevalent at takeoff.

Make sure your controls are calibrated correctly and all null zones are removed. Do you have rudder pedals?
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rodders47
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Re: Trim Takeoff Setting

Post by rodders47 »

Well the 172 Cessna that I am learning to fly in DOES have rudder trim. No I am not trying to fly on trims it just seems that whatever input I do, be it rudder or aileron are way too exaggerated compared to full size, so where should the null zones be set ??

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Re: Trim Takeoff Setting

Post by rodders47 »

Nick M wrote:rodders - fairly gentle right rudder input should be enough to stay on the centreline during the take-off roll and climb-out.

Your flight controls could be the culprit. Either the calibration for your actual joystick or a possible Accu-Sim control surface defect such as a jammed hinge. I'm wondering if you've checked the maintenance hanger or done a pre-flight recently? Are you getting full and unimpeded control surface deflections and are your flight controls properly neutral when your joystick is in its centred position?

Cheers,
Nick
Hi Nick thanks for the above. Have checked maintenance hanger each flight, no probs.getting FULL deflection L and R BUT I cannot see how to tell if control i.e. aileron or rudder is CENTERED, well yes I can see that on the walk around but is it REALLY centered? Seems to me when flying the aircraft that the controls have not been setup correctly, and I say that as a retired Aircraft engineer, but I cannot see how I can center them in the simulation.

Maybe just me but I have never landed off runway in the many number of touch and goes that I have done in real life but on the sim,I have not made ONE good landing yet after numerous tries?

I am using a SAITEK X52 pro joystick setup that I setup within FSX for the buttons etc.

After re-reading your reply Nick, yes roll out on runway slight rudder input all down center line no probs, as soon as wheels off the deck the aircraft veers Left, try correction with aileron, see slip ball, correct with rudder, very difficult, only way to do a good and proper takeoff with this aircraft on this sim is to set runway direction and engage auto pilot asap !!! same as the landing sequence, So what am I doing wrong?
Last edited by rodders47 on 19 Dec 2014, 11:40, edited 1 time in total.

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Nick - A2A
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Re: Trim Takeoff Setting

Post by Nick - A2A »

rodders47 wrote:no probs.getting FULL deflection L and R BUT I cannot see how to tell if control i.e. aileron or rudder is CENTERED, well yes I can see that on the walk around but is it REALLY centered?
Yes, checking the controls during the walk-around is as good a way as any. At least in the sim you can 'cheat' and move your joystick whilst examining the control surfaces from outside. It should be pretty evident if the rudder for example is deflected when you let go of your joystick. Also keep a look out for any twitching/jumping. Another clue is the position of the yoke in the virtual cockpit. Does its movement correspond with what you're doing with your joystick and is it perfectly level and motionless when you let go?

With respect to sensitivities/null zones I'd recommend trying with both all the way to the left (i.e. very low sensitivity, but no null zone.)

You don't mention what controller you're using for your rudder axis. If it's a twist handle joystick like I use, rudder control is a bit tricky in FSX. If so, it could be worth experimenting with 'auto-rudder' in the realism settings.

Hope this helps,
Nick

...Just read your edit rodders. It looks like you've got a twisty joystick too. Shouldn't be a problem provided you haven't got the sensitivity set too high, but of course it's nothing like rudder pedals you'll be used to in the real thing. It may just be a case of experimenting with the controller settings which work best for you. Even with real world flying experience in a C172, the flight controls in FSX will take a bit of getting used to!

Just a though, but have you also double checked your weight and balance to ensure you've got a more-or-less equal quantity of fuel in each wing tank?
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Re: Trim Takeoff Setting

Post by rodders47 »

yes Nick I am using the twist rudder joystick, am on holidays in the UK at the moment so have this system, at home I use rudder pedals.

Yes have tried with 1 pilot, 2 up front and then 4 on board and full baggage hold, none of these made any perceivable difference, although they sure should have. !! My Main problem is that I can navigate TOO and airport but can't land the bugger :-(

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Re: Trim Takeoff Setting

Post by Oracle427 »

Are you referring to the rudder trim tab on the outside of the aircraft that can be bent for adjustment? It sounded like you were talking about a trim setting that can be adjusted within the cabin. What model is this in the RW?

You need to fly the sim with very small and gentle inputs. You don't get the same feedback as on the real aircraft. If you are overcontrolling, relax your grip and hold the stick with your fingertips to try and reduce the tendency. Don't think in terms of pushing the stick and instead apply pressure to it.

Personally, I think it will be a little more difficult to use a twist rudder because they have a very small range of travel, little movement equals big deflection changes.

The term veer doesn't make it clear what is happening. Is the aircraft yawing and banking to the left or just one of the two? What is the difficulty in arresting the action of the aircraft to go off course? Do you not have enough control authority to stop this? You need to use the primary flight controls to keep the plane on course.

A real 172 will quickly go off the runway and bank to the left once airborne if no right rudder is applied.

Also have you downloaded and installed the latest patch? Perhaps there was something fixed in a subsequent patch that you do not have.

I recommend all null zones be set to zero and all axis set to max sensitivity.
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Re: Trim Takeoff Setting

Post by rodders47 »

Hi oracle, well the Cessna that I am learning to fly has rudder trim INSIDE the cockpit, as an adjustable lever similar to and located near the fuel tank selector. Not totally sure of model but is a carby engined unit and about 1980 version.

Well let me put it this way. Once I lift off the runway there is a very distinct turn to the left, I try correcting but I guess over correct ending up in this see sawing motion, this coupled with what I perceive as not normal in real aircraft steep climb makes life somewhat busy, not like what I have been doing in all weather and winds in the many circuits and touch and go's.. I can only think that somewhere I have settings incorrect ??

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Great Ozzie
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Re: Trim Takeoff Setting

Post by Great Ozzie »

Oracle427 wrote:What model is this in the RW?
Hey Oracle,

An N model I used to fly had rudder trim.

-Rob
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Oracle427
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Re: Trim Takeoff Setting

Post by Oracle427 »

I didn't know they had that. I've never come across it before and our N doesn't have that feature.

I tried searching for a POH with this after reading the recent posts, but couldn't find one. Do you have an example for my curiosity?
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Great Ozzie
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Re: Trim Takeoff Setting

Post by Great Ozzie »

If you google "C172P AFM HB-CIA" and download the pdf that says "seite 1 von 85", you can find rudder trim mentioned in e.g. section 7. My hardcopy for a '79 N has the same text.

It seems it was an option (from the description).
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Re: Trim Takeoff Setting

Post by Lewis - A2A »

rodders47 wrote:Well let me put it this way. Once I lift off the runway there is a very distinct turn to the left, I try correcting but I guess over correct ending up in this see sawing motion, this coupled with what I perceive as not normal in real aircraft steep climb makes life somewhat busy, not like what I have been doing in all weather and winds in the many circuits and touch and go's.. I can only think that somewhere I have settings incorrect ??
One thing to remember here is that the simulated version is the 172R, its a different shape power plant and systems to what you are currently learning to fly in so keep that in mind when expecting it to fly like a 172N. Also remember to fly it as you would in the real world, keep the pressures on the yoke and subtle movements, you should have no issue keeping the pitch correct on takeoff.

You also say you are using a stick, this is going to play havoc with your mind, as well as transitioning to a simulation of a slightly different variant aircraft you are also swapping controls altogether. I'd wager that if you had a yoke you would find the transition much easier. You can test your stick by sitting in the cockpit and moving the control surfaces to the stops, when at the stops you will hear the clonk as you hi the stops. This should help you determine exactly how much stick travel you have to play with.

cheers,
Lewis
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rodders47
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Re: Trim Takeoff Setting

Post by rodders47 »

Thanks for all the info guys.
I did a walkaround and noticed that neither the aileron nor rudder trims work, elevator does. So I moved all the sliders to the left, sensitivity and null, and set take off trim to just below the K (2 pob and 85 kg baggage) and it flew hands off straight down the runway just needing a bit of elev. trim input, just like the real one feels.. Have just done 10 touch and goes now if only I can do 10 without 1 bouncing one LOL and that is in real life as well ...

Thanks again

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Re: Trim Takeoff Setting

Post by Nick - A2A »

Glad to hear you've got things sorted rodders! :)

Just to clarify, the bendable rudder trim tab on the C172 is not simulated. I guess it's possible we'll see something like this added in future updates if the scope of Accu-Sim is expanded to model 'mis-rigged' aircraft as Scott mentioned in this post. I don't believe that real C172's have any form of external aileron trim tabs (unless we're talking about a mod like this) but may stand to be corrected...

All the best,
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Oracle427
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Re: Trim Takeoff Setting

Post by Oracle427 »

Glad to hear that Rodders47, but I would suggest increasing the sensitivity sliders toward max if not all the way to max while leaving the null zones at zero. I'm not sure if leaving the sensitivity at the fat left reduces control authority, but I feel that it would condition one to use the lightest touch possible which is the most like the real thing. In any case, everyone's workstation is different, so it's never a one size fits all solution. :)
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rodders47
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Re: Trim Takeoff Setting

Post by rodders47 »

I was just under the impression that if the trim control could be setup on the joystick then it would work on the aircraft, but I now realise that this 172 has been modeled on the Full Size which does not have aileron trim or Rudder trim.

Changing the sensitivity to max right for all flight controls, with null zone max left, has made the aircraft feel and respond like the real thing. Thanks guys now I can enjoy the Cessna

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