C172 Trim Not Correct

[andrew737]

Hi Guys

May I politely request some support here.

I have a scenario that does NOT match up even closely to real world flying in a C172 R or S model.

I fly and instruct in these planes and have built a Simpit to try and practice my own personal flying & teaching techniques.

Real Life Scenario:

*Straight & Level 2100 rpm 'Trimmed'

*Power Idle, Hold Attitude (applying back pressure)

*Wait for white arc & apply 20 degrees Flap

*Wait for 75kts and 'GENTLY' reduce pitch attitude to maintain 70kts

*With the attitude 'SELECTED' - 'HELD' - Trim is then required (About 2-3 turns of the trim-wheel) to 'TRIM' the new attitude

In the A2A C172 this is not the case; very little trim, if any is required - Guys, honestly this is not right.


I like A2A very much and I love the products, please take the critique constructively.

What would be very useful is a slider or parameter that can change the sensitivity of the trim for specific scenarios

Kind Regards & Many Thanks

Andrew

[Oracle427]

Can you provide details such as an ATIS?
Altitude the manuever was performed at?
Exact loading of aircraft including weight and balance and CG?

In the meantime I'll go up and test this in my 172SP in an hour and post results.

I will test if I need to put in two to three turns off nose up trim to hold 70 knots at idle with 20 degrees of flaps when transitioning from the previously noted config.

[DHenriques_]

Can you provide details such as an ATIS?
Altitude the manuever was performed at?
Exact loading of aircraft including weight and balance and CG?

In the meantime I'll go up and test this in my 172SP in an hour and post results.

I will test if I need to put in two to three turns off nose up trim to hold 70 knots at idle with 20 degrees of flaps when transitioning from the previously noted config.

I could be mistaken but it sounds to me like the poster is seeking the same ratio of movement for the sim trim wheel as found in the actual aircraft.
Dudley Henriques

[andrew737]

Can you provide details such as an ATIS?
Altitude the manuever was performed at?
Exact loading of aircraft including weight and balance and CG?

In the meantime I'll go up and test this in my 172SP in an hour and post results.

I will test if I need to put in two to three turns off nose up trim to hold 70 knots at idle with 20 degrees of flaps when transitioning from the previously noted config.

Hi Oracle

Yes!

1050ft QNH, Full fuel, me (200lb), pax (175lb), max 7lb in the luggage and noone in the rear seats

Thanks very much

[andrew737]

Can you provide details such as an ATIS?
Altitude the manuever was performed at?
Exact loading of aircraft including weight and balance and CG?

In the meantime I'll go up and test this in my 172SP in an hour and post results.

I will test if I need to put in two to three turns off nose up trim to hold 70 knots at idle with 20 degrees of flaps when transitioning from the previously noted config.

I could be mistaken but it sounds to me like the poster is seeking the same ratio of movement for the sim trim wheel as found in the actual aircraft.
Dudley Henriques

Dudley,

Not quite; I would like the same ratio of 'TRIM' effect as found in the actual aircraft.

Can you see the difference or are these one and the same? (You were quite right; I don't know how to code simulator software!)

A setting or slider would really help

[DHenriques_]

Can you provide details such as an ATIS?
Altitude the manuever was performed at?
Exact loading of aircraft including weight and balance and CG?

In the meantime I'll go up and test this in my 172SP in an hour and post results.

I will test if I need to put in two to three turns off nose up trim to hold 70 knots at idle with 20 degrees of flaps when transitioning from the previously noted config.

I could be mistaken but it sounds to me like the poster is seeking the same ratio of movement for the sim trim wheel as found in the actual aircraft.
Dudley Henriques

Dudley,

Not quite; I would like the same ratio of 'TRIM' effect as found in the actual aircraft.

Can you see the difference or are these one and the same? (You were quite right; I don't know how to code simulator software!)

A setting or slider would really help

Code drives me nuts as well )

I'm fairly sure the trim ratio for the sim has been "adjusted" so that the simmer doesn't either have to drag the wheel off the table with the mouse or hold the mouse button for an extended length of time. Could be wrong here but as I remember it this was the problem we faced during the beta.
Dudley Henriques

[andrew737]

Code drives me nuts as well )

I'm fairly sure the trim ratio for the sim has been "adjusted" so that the simmer doesn't either have to drag the wheel off the table with the mouse or hold the mouse button for an extended length of time. Could be wrong here but as I remember it this was the problem we faced during the beta.
Dudley Henriques

Interesting Dudley, hmmm, maybe here is where the problem lies?

Do you have any more info on this?

Kind Regards

Andrew

[Oracle427]

I can confirm that the aircraft required 2 cranks by hand from top of the wheel to the bottom to trim nose up to maintain 70 knots.

Aircraft had 25G of fuel, the pilot at 160 lbs. About 20 lbs in the baggage.

Alt was 3500 MSL, temp 31C, baro 3004

empty weight 1733.7 lb
MTOW 2550.0 lb
Arm 41.476 in
Moment 71.907 in lb/1000

[DHenriques_]

Code drives me nuts as well )

I'm fairly sure the trim ratio for the sim has been "adjusted" so that the simmer doesn't either have to drag the wheel off the table with the mouse or hold the mouse button for an extended length of time. Could be wrong here but as I remember it this was the problem we faced during the beta.
Dudley Henriques

Interesting Dudley, hmmm, maybe here is where the problem lies?

Do you have any more info on this?

Kind Regards

Andrew

I think that might be it Andrew. I recall that the basic trim code in FSX at least was not consistent. We had some trouble getting things the way they should be. People with Saitek Trim Wheels were having issues. I tried one myself and had issues.
If I remember right the final solution was a compromise on the wheel movement ratio in the sim vs the actual movement of the trim wheel in the airplane.
Dudley Henriques

[andrew737]

I can confirm that the aircraft required 2 cranks by hand from top of the wheel to the bottom to trim nose up to maintain 70 knots.

Aircraft had 25G of fuel, the pilot at 160 lbs. About 20 lbs in the baggage.

Alt was 3500 MSL, temp 31C, baro 3004

empty weight 1733.7 lb
MTOW 2550.0 lb
Arm 41.476 in
Moment 71.907 in lb/1000

Thanks Oracle, that's really helpful.

I'm back in the air Tuesday, Ill see if I can get some footage of it too.

Its the same in the C172 N as well.

Thanks again

Andrew

P.S. Would have loved to have done the test with you!

[andrew737]

Interesting Dudley, hmmm, maybe here is where the problem lies?

Do you have any more info on this?

Kind Regards

Andrew

I think that might be it Andrew. I recall that the basic trim code in FSX at least was not consistent. We had some trouble getting things the way they should be. People with Saitek Trim Wheels were having issues. I tried one myself and had issues.
If I remember right the final solution was a compromise on the wheel movement ratio in the sim vs the actual movement of the trim wheel in the airplane.
Dudley Henriques

That makes total sense.

Is there a way I can re-adjust this ratio?

Kind Regards

Andrew

[Oracle427]

I got footage with my go pro will try to upload later. No idea if it will be useful.

[Hook]

Dudley: Coding drives us ALL nuts. Haven't you ever noticed that coders are a little... strange?

Oracle: The video will be interesting. Please post it.

Andrew: Normally I could tell you what to adjust but the variable is set to zero in the config files, so they're doing custom processing with it and it's hidden somewhere else. Sorry 'bout that.

Hook

[DHenriques_]

I think that might be it Andrew. I recall that the basic trim code in FSX at least was not consistent. We had some trouble getting things the way they should be. People with Saitek Trim Wheels were having issues. I tried one myself and had issues.
If I remember right the final solution was a compromise on the wheel movement ratio in the sim vs the actual movement of the trim wheel in the airplane.
Dudley Henriques

That makes total sense.

Is there a way I can re-adjust this ratio?

Kind Regards

Andrew

You might be able to by fudging some code but I'd advise against doing that. With Accusim operating outside the basic sim code you could easily screw the pooch. But consider our basic logic as sound if you can. To move that trim wheel at the same ratio it moves in the real plane you would need a long arm on that mouse OR have a long wait for that trim wheel to rotate around to match the actual wheel. Consider as well that you will have to be flying the aircraft while all this is going on. ))))))
Just musing here of course but I do believe our thinking on this issue was sound.
DH

[DHenriques_]

Dudley: Coding drives us ALL nuts. Haven't you ever noticed that coders are a little... strange?

Oracle: The video will be interesting. Please post it.

Andrew: Normally I could tell you what to adjust but the variable is set to zero in the config files, so they're doing custom processing with it and it's hidden somewhere else. Sorry 'bout that.

Hook

LOL I've always said I had the easy job advising on flying qualities and performance. The coders transitioning all this "advice" into the sim as workable have the real hard part in the sim equation.
D