The gearing choice has nothing to do with precision. It's chosen so the pilot has the mechanical advantage to be able to move the trim with air loads on the stabiliser. You have more than enough precision with the electric trim and that makes the wheel whizz round at several revolutions per second. If anything I'd say the low gearing makes manual trim harder, because of the amount of movement needed to make even minor changes.

 

I agree the primary reason for the choice is mechanical advantage. I didn't say it wasn't. I said it allowed for more precision, regardless of its consideration as a primary factor or simply a byproduct of the choice.

 

It doesn't make it harder. It requires more spinning and more time, but the yield is mechanical advantage (as you mentioned), and precision.

 

If the wheel takes four rotations to move one unit, I have a range of 0.25 units over 360 degrees. This means that I can fine tune within 0.25 units over the 360 degrees of motion. This gives me more precision.

If the wheel takes one rotation to move one unite, I have a range of 1 unit over 360 degrees. This means I can fine tune within 1 unit over the 360 degrees of motion. This gives me less precision, comparatively.

Thanks for the info, very helpful!

 

Ben

I agree the primary reason for the choice is mechanical advantage. I didn't say it wasn't. I said it allowed for more precision, regardless of its consideration as a primary factor or simply a byproduct of the choice.

 

It doesn't make it harder. It requires more spinning and more time, but the yield is mechanical advantage (as you mentioned), and precision.

 

If the wheel takes four rotations to move one unit, I have a range of 0.25 units over 360 degrees. This means that I can fine tune within 0.25 units over the 360 degrees of motion. This gives me more precision.

If the wheel takes one rotation to move one unite, I have a range of 1 unit over 360 degrees. This means I can fine tune within 1 unit over the 360 degrees of motion. This gives me less precision, comparatively.

Kyle, sometimes less is more. You can have too much precision to be practical. The very low gearing does make it harder to manually trim accurately, especially as you would flying with one hand and trying to trim with the other, probably using the crank to speed things up. The gearing on a 737 is in fact just under 10 turns per unit. That's a lot of winding.

Kyle, sometimes less is more. You can have too much precision to be practical. The very low gearing does make it harder to manually trim accurately, especially as you would flying with one hand and trying to trim with the other, probably using the crank to speed things up. The gearing on a 737 is in fact just under 10 turns per unit. That's a lot of winding.

 

I understand that less can mean more, and that there are break points for everything. I always hear airline operations people say "you can never be too safe," and I want to punch them because that would mean they'd be living in a bubble, in a max security facility, with armed guards, and constant medical attention. There's definitely a balance.

 

However, just as you pointed out in our conversation the other day, this discussion is getting polarized when it doesn't need to be. I never said more winding is better, or that super precision is desirable in all cases. I said it allowed for more precision. End of point. The rest are all inferences.

 

I rather like the precision that I'm allowed on the NG, to be honest. The time it takes to attain said precision does not inconvenience me too much, either. Keep in mind, that it would take something drastic for you to have to change several units in trim all at once. If something that drastic happens, you've got bigger problems.

In the real 737 the only time I have ever used the trim wheel other than configuring for deice was when the forward trim stopped working on one flight. It is a real pain to try to trim the real plane with the trim wheel. In the RW it is very easy to trim precisely with the trim switches on the yoke.

It is a real pain to try to trim the real plane with the trim wheel.

 

Almost need a wheel knob. It would probably still be awkward to use, though. Maybe a wheel stick like you used to see on old hand drills...haha.

 

 

...as if you needed another thing to get in the way of your foot when you're trying to get into the seat.

Almost need a wheel knob. It would probably still be awkward to use, though. Maybe a wheel stick like you used to see on old hand drills...haha.

 

 

...as if you needed another thing to get in the way of your foot when you're trying to get into the seat.

There is one. It's called the "shin smacker!" It's normally stowed flush in the wheel, except for de-ice config or QRH-y type ops. I've never had to use it in flight for realsies, but I guess it's a lesson you don't want to learn that it should always be stowed after use.

There is one. It's called the "shin smacker!" It's normally stowed flush in the wheel, except for de-ice config or QRH-y type ops. I've never had to use it in flight for realsies, but I guess it's a lesson you don't want to learn that it should always be stowed after use.

 

Haha. Awesome. Apparently someone beat me to it on that one. And I'm sure it's a lesson you wouldn't soon forget.

Going back to the original question. Does anyone know how to display the trim setting on the EICAS, ND or PFD. The reason for my question is that I am looking at building a 737 cockpit. I would use one monitor to display the outside view and a second monitor to display the PFD, ND, Upper and Lower EICAS. I realise that the default software is unable to display the trim anywhere other that the trim wheel but someone out there might know how to do it. It would also be useful to be able to display the Autobrake position digitally.

 

Phil

I realise that the default software is unable to display the trim anywhere other that the trim wheel but someone out there might know how to do it. It would also be useful to be able to display the Autobrake position digitally.

 

I'm sure the SDK would have a variable that gives a percentage or some value that you could interpret and display if you create a gauge for it.

There is no way to show trim position on the displays as there is no indication in the real one.

I think is possible to create a little gauge able to show it (using SDK). Then I think you can put the gauge on the 2d panel and also over the display you want.

I remember some discussions about the missing tooltip on the wheel, it is however useless. But, in this case, using an external hardware will need you to know the trim position, wich can be "seen" only using an external gauge made using ngx sdk, or, with another display, make a custom view on the VC trim.

About the real trim:

2 speeds: flaps up, low speed, flaps not up, high speed

2 up limits, 2 down limits, the flap position will vary also the up and down limit for electric operation, this means that depending on this you need to move manually more or less to reach the mechanical stops if needed (mostly on ground)

The best way to move the trim for deice is to use the electric switch until it stops, then continue manually until it stops, less work to do and faster.

If the trim is then manually moved over its electrical stop, you can still use the electrical for the opposite direction.

NGX simulates the stops, simulates the 2 speeds, and when no power is avaiable you can only manually trim by using the mouse over the wheel.

It is something that no other one simulated.

However, just as you pointed out in our conversation the other day, this discussion is getting polarized when it doesn't need to be. I never said more winding is better, or that super precision is desirable in all cases. I said it allowed for more precision. End of point. The rest are all inferences.

 

I rather like the precision that I'm allowed on the NG, to be honest. The time it takes to attain said precision does not inconvenience me too much, either. Keep in mind, that it would take something drastic for you to have to change several units in trim all at once. If something that drastic happens, you've got bigger problems.

More precision sounds good, so some people reading this might get the wrong idea. You say you didn't mean that it was a good thing but that's how it read.

 

The precision you can get in the NGX trim with a mouse wheel is good, but the gearing of your mouse wheel to the trim is much higher than the gearing of the trim wheel in the aircraft. If it was the same as the real thing does you'd soon get tired of setting trim that way.

In the real 737 the only time I have ever used the trim wheel other than configuring for deice was when the forward trim stopped working on one flight. It is a real pain to try to trim the real plane with the trim wheel. In the RW it is very easy to trim precisely with the trim switches on the yoke.

Quoted for truth.