FSX Default 800 braking effectiveness

[Maurice]

After having recently flown on a WestJet Boeing 737-800NG, I was struck by how long it takes a real 737 to come to idle speed as compared to how quickly the FSX default 800 comes to a full stop even with moderate manual braking and no autobrakes.

Does anyone know how to decrease the braking effectiveness? I know there is an autobrake scalar in the SimA FSX-Default-B737.cfg file but I am not using the autobrakes, so I don't understand why the plane slows down that fast.

Also, the plane always comes to a full stop on the runway and I have to step on the brakes to release the brakes after the full stop. It almost looks like the parking brake is on but it isn't, so I don't understand why I need to step on the brakes to enable the plane to move again.

Any suggestion would be greatly appreciated.

Thank you,
Maurice

[Kennair]

Hi Maurice,

Try fiddling with the toe brake scalar in the aircraft.cfg file.  Look for this section:

[brakes]
parking_brake = 1         //Parking brake available
toe_brakes_scale = 0.885  //Brake scalar
auto_brakes = 4
hydraulic_system_scalar = 1

Also you could look at the pneumatic system:

[pneumatic_system]
max_pressure=18.000000
bleed_air_scalar=1.000000

I seem to remember the max_pressure effects things like brakes.  Of course there's also the axis slope options in FSUIPC you could tweak?

As for the brakes needing to be stepped on before it'll move, again I'd be looking at the FSUIPC options to make sure you have the pot travel calibrated correctly, and there's no weird parameter such as "apply brakes when axis goes to minimum" (I'm sure you haven't got something like this, but worth a mention ) .

I usually find an aircraft that performs how I think it should then compare it's cfg file to see where I might be able to make some changes, unfortunately if it's built into the model file then you're buggered, find another aircraft.

Cheers,

Ken.

[blueskydriver]

You're using Sim-A, but with PM you would set the braking to release at 30kts. Although, my point is about when you bring the throttles out of reverse thrust back to idle (so this would apply to both programs). The brakes should release when your throttles get to idle position, so like Ken is saying if your pot travels are not calibrated correctly in FSUIPC you might not be hitting the idle position enough to release the brakes, but yet you're out of reverse thrust.

Also, are you seeing values for reverse thrust? You could be going to 100% as soon as you move the reverse thrust lever and that would be incorrect, as reverse thrust should be linear from 0-100%. Check that value, the throttle values, as well as your brake values in the FSUIPC Axis settings tab...

BSD

[Maurice]

Hi Maurice,

Try fiddling with the toe brake scalar in the aircraft.cfg file.  Look for this section:

[brakes]
parking_brake = 1         //Parking brake available
toe_brakes_scale = 0.885  //Brake scalar
auto_brakes = 4
hydraulic_system_scalar = 1

Ken.

This is interesting. The setting auto_brakes=4 is different on the PMDG NGX. There it says auto_brakes=0.
I have now changed the value to 0 and we'll see if that makes any difference.

As far as braking effectiveness, I'm not that concerned if the plane slows down too fast when I apply the brakes; I'm much more bothered by the fact it stops and does not move again until I re-apply the brakes & release them.

I seem to recall a setting somewhere that says something like fully applying the brakes engages the parking brake but I can't find it anymore (or I dreamt it  . I will keep looking for that as well.

Thanks,

Maurice

[Maurice]

You're using Sim-A, but with PM you would set the braking to release at 30kts. Although, my point is about when you bring the throttles out of reverse thrust back to idle (so this would apply to both programs). The brakes should release when your throttles get to idle position, so like Ken is saying if your pot travels are not calibrated correctly in FSUIPC you might not be hitting the idle position enough to release the brakes, but yet you're out of reverse thrust.

Also, are you seeing values for reverse thrust? You could be going to 100% as soon as you move the reverse thrust lever and that would be incorrect, as reverse thrust should be linear from 0-100%. Check that value, the throttle values, as well as your brake values in the FSUIPC Axis settings tab...

BSD

This isn't the problem at all in my case since I do not even need to use reverse thrust and if I do, I just have 2 switches instead of pots so reverse thrust is either on or off.

SimA also allows you to release the autobrakes when you apply the toe brakes but again, this does not apply since the same thing happens even if I do not arm the autobrakes.

My main problem seems to be that the plane comes to a full stop instead of coasting when I release the brakes. As I said earlier, it looks like the parking brake gets set somehow and only resets when I fully apply the toe brakes.

There has to be a simple solution to this but it evades me so far.

Thanks,
Maurice

[Maurice]

I think I fixed the problem by re-calibrating the brakes with FSUIPC. I may be wrong but I think that when I was applying the brakes after landing, the FSUIPC value was going too high and that applies the parking brake. So when I came to a full stop, I had to re-apply the toe brakes to release the parking brake.

So when I re-calibrated the brakes, I made sure to push the toe brakes as far as they would go before setting the value. When I land now, I do not push the toe brakes all the way to the end stop and that seems to have resolved the issue (at least I hope so 

Alway something new to learn in this business 

Thank you both again for your inputs anyway,

Maurice