f a LUA script is needed if you have SPX and Frictionality installed (FWIW I'm currently using Accufeel).

Not required Jarkko

I know PMDG don't like these types of addons because it messes with their creation, but I'd love to hear if Tabs or someone else (maybe even a beta member) would suggest something like this to "improve" the feel on landing etc.  If I hear that from them I'll go grab it while it's on sale.  

 

I used to use the FSUIPC friction script but turned it off for some reason.  I forget why.  

I have none of the software discussed above,

 

Where do I start? Purchase FSPS frictionality or FSUIPC (I have the registered version but haven't ever heard of DynamicFriction LUA script or the other fsuipc entry?)

 

 

FSUIPC (I have the registered version but haven't ever heard of DynamicFriction LUA script?

 

FSUIPC is a must if you ask me if you like to smooth out your axis to make your yoke or joystick movements match what the airplane should be doing.  It's MUCH better than the default FSX controls setup.  The friction LUA script is free with it too.  

 

I have no knowledge of the other software 

I find this thread fascinating. I had not realized how much the developers, technical team comprised of 77L experienced crew and a bunch of us ordinary folks that do beta testing missed this. Interesting. And yet, I missed the technical description of "stops in a dime/on a dime" in order to compare how my experience may compare to yours. The PMDG physics is not real complicated, a specific amount of autobrake results in a specific amount of deacceleration given dry conditions and loads within realistic range. Hitting the first high speed turn off at many runways is not unrealistic.

thx for replying 

I find this thread fascinating. I had not realized how much the developers, technical team comprised of 77L experienced crew and a bunch of us ordinary folks that do beta testing missed this. Interesting. And yet, I missed the technical description of "stops in a dime/on a dime" in order to compare how my experience may compare to yours. The PMDG physics is not real complicated, a specific amount of autobrake results in a specific amount of deacceleration given dry conditions and loads within realistic range. Hitting the first high speed turn off at many runways is not unrealistic.

Personally I never said it was unrealistic, I think it is pretty accurate based on my own testing and comparison with what is in the FCOM. I guess we're all just trying to figure out why this darn plane stops so quick. For me I think it's because I've been flying the NG and got used to seeing the end of the runway so often.

 

I have a question about the auto brakes. I know it maintains a rate of deceleration, so I guess as the aircraft slows down it reduces braking pressure to maintain the rate of deceleration selected. At what point does it stop trying to maintain that rate of decel and maintains a constant pressure to completely stop the plane?

 

 

I have a question about the auto brakes. I know it maintains a rate of deceleration, so I guess as the aircraft slows down it reduces braking pressure to maintain the rate of deceleration selected. At what point does it stop trying to maintain that rate of decel and maintains a constant pressure to completely stop the plane?

I would think that it would just use a constant rate of deceleration all the way to a stop?

 

 

tcas_climb, on 04 Jul 2014 - 9:44 PM, said:
I have a question about the auto brakes. I know it maintains a rate of deceleration, so I guess as the aircraft slows down it reduces braking pressure to maintain the rate of deceleration selected. At what point does it stop trying to maintain that rate of decel and maintains a constant pressure to completely stop the plane?
I would think that it would just use a constant rate of deceleration all the way to a stop?

 

First, as for reducing braking to maintain deacceleration. This is a common misconception about friction, as it turns out speed does not affect the force generated by friction but is just a function of the force applied to the surfaces and the coefficient of friction (F_friction= uF_normal). Granted this is for static friction but dynamic friction between metals is pretty close to static.

 

Refer to your FCTM. Some pretty interesting stuff, for example if you are using a higher value for autobraking than 1 or 2 in normal conditions then you are over braking [6.31]. Proper technique for disarming braking is to disarm auto before coming out of reverse thrust [6.32] and the paragraphs on reverse thrust [6.35] recommend that it be reduced below 60 kts slowly to idle at taxi speed.

 

My guess is if you are stopping surprisingly quick then you are using too high of a value for autobrake.

I find this thread fascinating. I had not realized how much the developers, technical team comprised of 77L experienced crew and a bunch of us ordinary folks that do beta testing missed this. Interesting.

 

I don't believe that they "missed it". I'm personally think that the wrote it down as being the way that things work in FSX. To give you an example. Below is a real world B737 pilot flying with the NGX. Rewind to 01:56:47

 

http://www.twitch.tv/f30gl/b/543483509

 

You will hear him say: "The rolling friction is ridiculous at some parts of this airport". So I'm not sure how much of this has got to do with scenery and how much with the "less than ideal" friction modelling in FSX.

Dan,

 

The default friction model in FSX & FS9 is way off, everybody knows that.  I don't understand why some get defensive when this is pointed out I don't think anyone here is saying PMDG have done a bad job or have got things wrong through lack of knowledge. They simply have done the best they can with a poor platform and kept it universal for everyone.  You will find many compromises in all aspects of casual desktop simulators.

 

Now I based my findings on  tests that I did in a simulator, this was way before the PMDG 777 was released and completely unrelated to product.  Once the product was out I decided to compare how the PMDG 777 compared to the sim, I was not surprised that it did not behave the same way. 

 

I consistently found that the PMDG 777 was able to stop much quicker than the sim.  Fortunately we have developers liks FSPS that now allow us to easily make adjustments to the friction model.  It took me well over 50 RTO's on the PMDG T7 and screwing around with the LUA script before it behaved more like the sim.

downscc, on 06 Jul 2014 - 05:32 AM, said:

First, as for reducing braking to maintain deacceleration. This is a common misconception about friction, as it turns out speed does not affect the force generated by friction but is just a function of the force applied to the surfaces and the coefficient of friction (F_friction= uF_normal). Granted this is for static friction but dynamic friction between metals is pretty close to static.

 

Refer to your FCTM. Some pretty interesting stuff, for example if you are using a higher value for autobraking than 1 or 2 in normal conditions then you are over braking [6.31]. Proper technique for disarming braking is to disarm auto before coming out of reverse thrust [6.32] and the paragraphs on reverse thrust [6.35] recommend that it be reduced below 60 kts slowly to idle at taxi speed.

 

My guess is if you are stopping surprisingly quick then you are using too high of a value for autobrake.

I have read that with Carbon brakes, sometimes using Autobrake 2 is actually better than 1 as with 2, the discs heat up to their optimum temperature quicker. Although I do tend to use 1 in the sim, apart from shorter runways or if flying the freighter and landing quite heavy. I slowly start feeding in manual braking (and hence disconnect Autobrake) at around 70kt, and kill the reverse by 60. 

 

Just out of interest, given that most of us use full reverse in the sim (well I have to as my hardware throttle is all or nothing.) so if the autobrake just gives a constant rate, then it should not matter if you use full reverse or not - stopping distance will be about the same.

My topic is now HOT! Come on!

Yori Smulders, on 06 Jul 2014 - 11:11 AM, said:

My topic is now HOT! Come on!

Ha ha congratulations!   

My topic is now HOT! Come on!

If not for you, I would not have considered SPX, so thanks Yori

 

Edit: And Rob