FS FORCE

Hi there,

I recently bought a Logitech Force 3D Pro for the express purpose of using it with FS Force 2 in FSX. I also own a TM Cougar, which I am very happy with, but when I learned about FS Force's trimming mechanism, I figured I should give it a try, as the lack of 'feedback' from the controls makes trimming much more difficult than I suspect it is in real airplanes.

I haven't bought the FS Force license yet, but have been testing the joystick with the demo version. Unfortunately, it seems for the moment than I just spent 50 Euros for nothing, as the trimming experience is worse now that it was before. Here's what my two main observations are:

- The plane (any plane) does not seem to want to hold the attitude I leave it in when I trim and feel the force on the stick fading away, meaning I am very near the in-trim setting for that speed. Instead, the VSI starts oscillating and the needle goes constantly from positive to negative and back, sometimes from +1500 fpm to - 1500 fpm (e.g. in the Baron 58 ) , which seems a ridiculous variation for an in-trim or near in-trim airplane. Needless to say, I can hardly hold an altitude or descent/ascent rate like this.
This could obviously be attributed to the joystick being oversensitive, but let me state that when I'm using the FSX trim method, I do not get things like that, i.e. I can trim the plane so that the VSI needle only moves a few fpm when the plane is near in-trim.

- Even maximum trim setting seems to be ineffective to correct an up or down tendency at a given speed. Latest try was with the stock 737-800, at a speed of ~250 knots, altitude 3-4K and trim at +100 (FS Force gauge). The nose was still dropping, although one would expect that it would in fact rise with such a high-nose up setting. Reaching the end of the trim scale seems to produce some strange "stiffness" on the stick (for lack of a better description).

Anyone else using this joystick and has the same issues? I would appreciate any pointers to a solution, as I would really like to buy the SW and enjoy a proper flying (trimming!) experience.

My settings are:
OS: Win 7 64
FSX: SP2 without any addons
Logitech software axis sensitivity settings: 15%
Logitech software axis deadzone settings: tried anything between 5% and 50% to avoid the oscillation, no good.
Standard profiles for airplanes in profile manager.
Maximum force settings on logitech software (including centering force).

Thanks!

P.S.: On a sidenote, I found the joystick itself being quite crappy in precision, but could not get anything else in the FFB market with the Sidewinder 2 and Saitex Cyborg not being sold anymore (at least I could not find any, save on e-bay). I was surprised (and saddened) to see that there is no FFB flight yoke for civilian sims, where trimming a plane is very much a given fact.
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Ipad Guide

The idea of the elevator trim is help the pilot to keep a specific IAS, not attitude or VS. You should search more info about the topic. It's one of the basis of aircraft commanding but as it is a non intuitive concept, everybody needs to learn about it reading articles or being taught by someone. I mean, it's difficult to find it out by anyone alone.
(Although it's true that you can use it to just fly straight en level if the IAS is not important)

Apart from that, the FFB is cool in concept, but needs of very high quality components to work as expected (i.e.: lots of $$$). As you already may know from the information in internet, the closest to the ideal is MS FFB2. Despite of that, it's still far from perfect, being the free play without forces around the center the biggest problem, which leads, as you describe, to unwanted control when all you want is the stick to stay in place.

For what I've read, Logitech is in the oposite extreme regarding quality, and so it is the performance of their legacy FFB joysticks. So, it's very likely that you spent that money for nothing.

It seems that these days people is willing to expend a quite big ammount of money in simming hardware. That means that nowadays a very high quaility force feedback stick could be built and sold. Unfortunately, force feedback is not popular, so it doesn't going to happen by now. And the worst is that the newest addition (also from logitech) still lacks of the needed quality, perpetuating the bad fame of force feedback.

Hi,

first of all, thanks for replying, I appreciate someone taking the trouble after 2 weeks no less

Concerning your comments on my post, I do know that you trim an airplane for an airspeed.

...when I trim and feel the force on the stick fading away, meaning I am very near the in-trim setting for that speed.

But through trimming for a specific airspeed, you get to trim also for an attitude or a vs in a climb/descent, provided that you keep that airspeed constant. And that is what I am saying in the post. In essence, my problem in point one is also keeping the airspeed constant, as the plane's nose oscillates up and down and it changes constantly.

I do completely agree on the rest, i.e. the FFB controllers status in the market. It seems surprising that there is no flight yoke for civilian aircraft (as most modern military jets don't get trimmed in-combat/enroute by the pilot) with a decent FFB system.

Again, thanks very much for taking the trouble to reply.

On a related subject (with regards to trim), I am wondering about the implementation of the FS-Force trim mechanism as well. For a start, it seemed strange to me that I could get the plane trimmed on the FSX trim system using the same Logitech controller, but I can't with the improved FS-Force one. So, I've been reading again Russ's comments on how the trim system works, specifically:

In other words, when you apply nose-down trim, what's actually happening (in the flight model) is that the elevator is moving down, causing the aircraft to pitch down, and vice versa for nose-up trim. So while you may visually see the trim tab moving in FS, what you're really doing, in terms of the flight dynamics, is moving the elevator. There is an interesting side-effect to this : by holding the joystick steady and making trim changes (under the FSX system) you can actually climb and descend the aircraft!! Of course you cannot do that in a real aircraft.

@ Russ: I think there is a misconception here. True, in a real airplane, using the trim wheel or rocker directly moves the trim tab. But indirectly, you (can) move the elevator too. It would be odd from a physics perspective if you couldn't, since the trim tab applies force on the elevator. If you are in-trim and apply some more trim, let's say nose-down, the trim tab will rise into the air-stream a bit more and the elevator will go Trailing Edge Down (TED) as a result. And then the plane will start descending and the airspeed will increase to the new in-trim airpseed. Of course, noone recommends flying like this. But that doesn't change the fact that it can be done in real airplanes. So MS's implementation is not wrong in that respect, it just doesn't model the tab movement, but merely (from what you say) changes directly the elevator angle.

Here's a couple of links I found from a quick search to support what I stated:

http://www.pilotfriend.com/training/fli ... g/trim.htm
Check what they say about "Emergency Trim Use" towards the end. In the event of the yoke not being able to move the primary control surfaces, trim can be used to do that.

http://www.airliners.net/aviation-forum ... main/62353
Although the subject is different, there is 'Reply 5' stating "I was taught to NOT use the trim tab to a) climb b) decend c) flaring.", which to me indicates that you can in fact climb and descend with the trim in a real airplane and 'Reply 11' that says "Thou shalt not fly the plane with the trimmer".

Now I obviously don't know how Russ's view of trim is implemented in the FS-Force software. I am just curious if by taking measures(?) to not allow the plane to climb/descent using trim, something in the natural trim mechanism is in fact broken.
This is by no means to bash the software, I think it's excellent that people take the trouble to improve stuff and in that spirit I am wondering if FS-Force can be improved as well.

Any feedback on this is welcome, especially if there are some of you who actually fly planes for real.
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Mercedes-Benz Slk-Class Specifications

crim3d wrote:The idea of the elevator trim is help the pilot to keep a specific IAS

Well, I don't think that is quite correct. IAS is actually controlled by adjusting pitch, which is controlled with the elevator. I think that is maybe what you were trying to say. The purpose of elevator trim is to relieve control pressure.

If the pilot wants to fly at a specific IAS, he adjusts the pitch of the aircraft until that speed is attained. He then adjusts power to attain the desired vertical speed (straight and level, or a climb/descent). But after all that is set up, the airplane is probably out-of-trim, and the pilot is having to exert pressure on the yoke to fight the slipstream, so he uses trim to eliminate that pressure.

Zeus_6 wrote:@ Russ: I think there is a misconception here. True, in a real airplane, using the trim wheel or rocker directly moves the trim tab. But indirectly, you (can) move the elevator too.

You're right, you can, but please re-read my comments, taking note of the hilight:

There is an interesting side-effect to this : by holding the joystick steady and making trim changes (under the FSX system) you can actually climb and descend the aircraft!! Of course you cannot do that in a real aircraft.

My comments assumed the joystick/yoke was not being allowed to move. However, in one sense what I said was incorrect. If the yoke is not allowed to move, you actually can climb and descend an aircraft using trim, (as the above mentioned article mentioned) but the effect is opposite to what you would expect. Nose-up trim would cause the airplane to descend, and nose-down trim would cause the airplane to climb. (Think about how the trim tab moves.) This is opposite to what happens in MSFS. Also, since the trim tab is so small, the effect would be quite minimal.

But now lets consider a "hands-off" situation, ie. allowing the joystick/yoke to move freely. In this case, you can fly a real aircraft using trim, if you want to, just like you can in MSFS. As far as I know, many real-world autopilot system control the airplane by manipulating the trim tab. The thing to realize, though, is that when you adjust trim in a real airplane, the yoke will most definitely move in response, but in MSFS, using default trim and a mechanical josytick, the joystick will obviously not move on it's own. So the question is, how did MS successfully mimic this behaviour of being able to fly an aircraft using only trim when the joystick is just going to stay in one place? As I mentioned in my help documentation, they directly connected the trim control to the elevator, so that when you adjust trim you are directly manipulating the elevator (in terms of flight dynamics, not the visual model).

Zeus_6 wrote:Concerning your comments on my post, I do know that you trim an airplane for an airspeed.

it seems to be an unavoidable law of all forums. When you decide to post a reply then there is a high probability that you are missing the most important line of the original post
Not knowing you at all, I was preparing myself to apologize for the error in the case that you already knew that and you got angry. That's been the case, but you didn't get angry, this way communication becomes a pleasure.

RussDirks wrote:Well, I don't think that is quite correct. IAS is actually controlled by adjusting pitch, which is controlled with the elevator. I think that is maybe what you were trying to say. The purpose of elevator trim is to relieve control pressure.

Corrected once again. Thx

RussDirks wrote:

There is an interesting side-effect to this : by holding the joystick steady and making trim changes (under the FSX system) you can actually climb and descend the aircraft!! Of course you cannot do that in a real aircraft.

My comments assumed the joystick/yoke was not being allowed to move...

I totally agree, I completely missed the part about not allowing the yoke to move. In a real airplane the yoke does move to precicely match the current elevator deflection.

RussDirks wrote:But now lets consider a "hands-off" situation, ie. allowing the joystick/yoke to move freely.
...
As I mentioned in my help documentation, they directly connected the trim control to the elevator, so that when you adjust trim you are directly manipulating the elevator (in terms of flight dynamics, not the visual model).

But that is in fact correct, as far as the end-result is concerned. They do not implement a trim tab in the flight model, so they directly change the elevator deflection angle (I'll use elevator as an example). What is actually important is to see what measures have been taken in FSX standard model to emulate the yoke deflection that would result in a real plane.

Let's assume as an example an elevator moving between -40 degrees Trailing Edge Down (TED) and 40 degrees TEU, as well as a joystick that moves in the y-axis between say -120 (aft) and 120 (forward) units.

If you trimmed the airplane at (elevator) -20 degrees (TED), then the joystick "centre" position should be at 60 (fwd) units, to match the "nose down" pressure applied. This obviously can't be done on a mechanical joystick, so what have they done to compensate, do you know (I've read about the "virtual linkage" in your notes, but didn't quite get what you mean)?
I mean, you shouldn't have the full joystick fwd range available, as this would normally result in an additional -40 degrees TED at joystick 120 fwd position, wheareas the elevator only has -20 degrees to go to max postition (i.e. it can't go to -20 (trimmed) + (-40) (deflected) = -60!).

So how did they solve that, do you know? Is it by having assymetrical input resolution in the fwd/aft direction after trimming? Meaning, for the same physical stick deflection, different y-axis values register in the fwd than in the aft direction (though, that would cause a higher resolution in the stick aft (in the example) direction, to compensate for the additional 20 degrees the elevator angle has to travel towards full TEU due to trim, which doesn't seem to be the case, as far as I can practically see).
The other solution would be to create a deadzone between 0 and 60 degrees fwd (in our example of -20 degrees TED trim), but I don't see anything like that, as soon as you move the joystick fwd the nose-down attitude immediately appears (plus, it would create the opposite issue with aft deflection, namely you woudn't be able to reach 40 degrees TEU, as you would have only 40 degrees available and you are at -20).

The other question is, how have you implemented it in FS-Force and why does it feel so radically different (to me, at least) with regards to sensitivity, when trimmed? Why, using the same controller, I can fly straight and level at any speed with the basic trim system, whereas I can't do the same with the FS-Force one? Have you tried to incorporate an actual trim tab in the flight model instead of moving the elevator directly?

Again, don't get me wrong, I'm merely trying to figure out where the problem I'm facing is, so I can maybe help solve it and buy your very nice product
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Extreme vaporizer

If you trimmed the airplane at (elevator) -20 degrees (TED), then the joystick "centre" position should be at 60 (fwd) units, to match the "nose down" pressure applied. This obviously can't be done on a mechanical joystick, so what have they done to compensate, do you know (I've read about the "virtual linkage" in your notes, but didn't quite get what you mean)?
I mean, you shouldn't have the full joystick fwd range available, as this would normally result in an additional -40 degrees TED at joystick 120 fwd position, wheareas the elevator only has -20 degrees to go to max postition (i.e. it can't go to -20 (trimmed) + (-40) (deflected) = -60!).

I think they have in fact implemented a simple offset: the elevator position is determined by the joystick position +- an offset based on the trim tab position. That's what I meant by virtual linkage. So in effect you can get more or less elevator travel by adjusting trim. You can see this flying the default 747, without FS Force. Before takeoff, put in full nose down trim and then begin the takeoff roll. Notice that you can barely rotate the nose wheel off the ground. But now do it again with full nose up trim. Hold the joystick in the neutral position, and the nosewheel will lift off at about 80 kts. Adjusting trim seems to give you more or less elevator travel.

The other question is, how have you implemented it in FS-Force and why does it feel so radically different (to me, at least) with regards to sensitivity, when trimmed? Why, using the same controller, I can fly straight and level at any speed with the basic trim system, whereas I can't do the same with the FS-Force one? Have you tried to incorporate an actual trim tab in the flight model instead of moving the elevator directly?

I haven't been able to duplicate your results regarding pitch sensitivity. I went and dug my Logitech Force 3D Pro out of the closet, and tried it out. Pitch sensitivity seemed about the same with or without FS Force. Keep in mind that the Baron is very sensitive in the pitch axis.

As far as how FS Force works. It does two things. First it blocks trim commands from reaching the FS trim system. Second, it turns on the FF centering force, and adjusts its strength based on your airspeed and the profile you're using. The center point of the centering force can be programmatically moved anywhere along the pitch axis the joystick. When you make trim changes, FS Force simply moves the center point of the centering force closer or further away from where you currently have the joystick positioned, giving you the feeling of being either in trim or out of trim. It doesn't make any changes to the flight model of the aircraft.