So all in all. It seems that the PMDG 777-200LR braking is about right for a real 777-200LR on a dry grooved runway with tyres and asphalt in perfect condition.

 

However it is not accurate in rain, ice, on contaminated or compromised surfaces etc, but an addon which effects ALL of FSX (including default aircraft, other addons by other companies etc) can simulate these other conditions.

 

Its basically like:
Flightsim misconception: The plane is bigger so the brakes won't work as well

Reality: The plane is bigger so they put 12 wheels on it and made the breaks work better to compensate.

 

Remember also: 737-800 typical V-REF is around 139 flap 30. 777-200LR typical VREF is around 137 flap 30. The bigger wings/flaps make more lift so the approach speed is lower, even with the larger/weightier plane.

 

Several ATC guys I know have mentioned that the A380 has a lower approach speed than most 737-800's. (but takes longer to stop, in no small part due to the fact that only 2 out of it's 4 engines can go into reverse thrust!)

 

Nevertheless, without this thread I wouldn't have heard of SPX, so... good thread  B)

I just tried SPX, while it does make landing and taking off in adverse weather conditions more interesting, one thing i noticed when i tried an aborted takeoff in heavy rainfall (SPX indicated that the friction was very poor). The brake temperature indication on the GEAR synoptic is much lower with SPX ON than with it OFF. Aborting takeoff with a GW of 689,000lbs at HKJK at a speed of 145kts peaked the indications at 4.8, while with SPX OFF the indications got up to 6.7 before the aircraft came to a complete stop (somewhere below 40kts). So when the developers say that using things like friction modifiers can produce non-normal behaviours, this is an example of what they meant. One could probably argue that the less effective braking in heavy rainfall/standing water would automatically produce lower brake temperatures, but i will leave that to the Physicists and engineers to decifer.

No point trying to compare the two with any kind of rain or snow. The PMDG 777 behavior is completely unrealistic, as you say the T7 still behaves like it is on a perfect bone dry runway.

 

Also make sure you have Anti skid turned off in SPX, the PMDG A/B already has this built in.  As usual it is all in the documentation that comes with SPX.

 

Regards

 

 

(but takes longer to stop, in no small part due to the fact that only 2 out of it's 4 engines can go into reverse thrust!)

 

This doesn't really make any sense, at least on a non contaminated runway, autobrakes modulate and reverse thrust is not factored into stopping distance. Also the A380 has brake to vacate as standard.

Its basically like:

Flightsim misconception: The plane is bigger so the brakes won't work as well

Reality: The plane is bigger so they put 12 wheels on it and made the breaks work better to compensate.

Unless my memory is off, I thought I read that they put twelve wheels on the main gear for weight reduction since the other option would have been to go the way of the DC-10-30 by adding the center landing gear.

 

 

Unless my memory is off, I thought I read that they put twelve wheels on the main gear for weight reduction since the other option would have been to go the way of the DC-10-30 by adding the center landing gear.

Pretty much.

 

 

 

Its basically like:
Flightsim misconception: The plane is bigger so the brakes won't work as well
Reality: The plane is bigger so they put 12 wheels on it and made the breaks work better to compensate.

Interesting calculation (and quick n dirty): 737 landing at 60tons = each brake unit has to absorb the energy of 15tons traveling at say 130kt. Now lets take a 77L landing at 215tons, that's 17.9tons per brake travelling at 140kt. Scale that up to a rejected takeoff; 737 - about 18tons per brake. 77W - 29.25tons per brake. So yeah, better brakes with more discs on the bigger planes. RE A380, I believe it only has brakes on 16 of the 20 main gear, that coupled with half reverse thrust accounts for looong rollouts.

 

 

RE A380, I believe it only has brakes on 16 of the 20 main gear, that coupled with half reverse thrust accounts for looong rollouts

 

Read the whole thread, reverse thrust does 'not' affect roll out distance. Autobrakes modulate on every setting except MAX/RTO

 

Once again, the A380 uses brake to vacate (BVT) it aims to vacate you at whatever turn off you have selected.

FLEX1978, on 04 Jul 2014 - 12:03 AM, said:

Read the whole thread, reverse thrust does 'not' affect roll out distance. Autobrakes modulate on every setting except MAX/RTO

 

Once again, the A380 uses brake to vacate (BVT) it aims to vacate you at whatever turn off you have selected.

You are correct. 

Read the whole thread, reverse thrust does 'not' affect roll out distance. Autobrakes modulate on every setting except MAX/RTO

 

Once again, the A380 uses brake to vacate (BVT) it aims to vacate you at whatever turn off you have selected.

 

That is a pretty neat feature indeed!

 

The shortest stopping-distance is archieved by max. MANUAL braking combined with reverse thrust. 

 

I've taken Rob's advice and purchased Sim Physics X - at the PC Aviator Sale...to fix the Limitation of braking.

I've taken Rob's advice and purchased Sim Physics X - at the PC Aviator Sale...to fix the Limitation of braking.

 

A cool little extra thing I noticed through SPX -The PMDG 777 Anti ice switches work perfectly with this addon (Auto and manual use)  But make sure you switch off Elevator & rudder icing, I think that was designed for light aircraft. 

 

Am very pleased with what FSPS have been releasing over the last year or so. A very smart bunch of developers, just be sure to read the docs that come with the products! :)

A cool little extra thing I noticed through SPX -The PMDG 777 Anti ice switches work perfectly with this addon (Auto and manual use)  But make sure you switch off Elevator & rudder icing, I think that was designed for light aircraft. 

 

Am very pleased with what FSPS have been releasing over the last year or so. A very smart bunch of developers, just be sure to read the docs that come with the products! :)

Yeah I have done that - will SPX give me realistic braking?? What about the Cockpit effects camera shaking will that interfere with other addons ?? After the reading the manual Im "flapping" my next takeoff/landing...seems the conditions monitored and changed will add that realism to takeoffs and landings.

Yeah I have done that - will SPX give me realistic braking?? What about the Cockpit effects camera shaking will that interfere with other addons ?? After the reading the manual Im "flapping" my next takeoff/landing...seems the conditions monitored and changed will add that realism to takeoffs and landings.

 

I use EZDOK so have the camera options turned off.  Also Anti skid & Rudder/Elevator icing simulation is turned off.  Everything else  will give you a more realistic and challenging experience.

I've been struggling with the decision of using SPX or not to be honest, on the up side, it provides reduced braking and reduced acceleration during takeoff on a wet runway, on the down side, it isn't compatible with the dynamic friction script I use so taxi fuel will be high and the aircraft feels funny running on the default fsx friction values, and the brake temperatures appear to be lower than they should be, i.e. doing an aborted takeoff at MTOW will make the brakes hot enough to trigger a brake temp alert but never hot enough to blow out the tires.

 

Still trying to see what I can live with.

That's strange Bryan, I use the dynamc friction script (Modified after doing tests on a 777 sim) And I also get tires blowing out.  Did you disable Anti skid as I suggested?

To get the best out of SPX, you probably need:

http://secure.simmarket.com/fsps-frictionality-fsx.phtml

 

SPX and Frictionality are sync'd together.

 

 

It overrides the sim1dll, and you use it without the friction lua in fsuipc. I do have it, but not tested it yet. I need to get SPX first which I will today.