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mustiej

Any simple way to calculate flaps, derate etc?

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Hi guys,

 

I saw some videos about the PMDG's EFB in-game but I haven't really see anyone use it to calculate flaps or derate.. 

 

Any idea's if the EFB could do that? Since Topcat doesn't have the profiles yet... I have Avliasoft efb2 and PFPX but I don't think they have that..

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Just now, mustiej said:

Hi, thanks for the link. Does PFPX calculate derate and flaps?

Not for the -8 (yet??), but my understanding is PMDG is working to get that done. I think it comes down to the expense ($$) for the data.

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1 minute ago, pracines said:

Not for the -8 (yet??), but my understanding is PMDG is working to get that done. I think it comes down to the expense ($$) for the data.

Wait, I don't think PFPX calculates derates, you'll need Topcat for that? Which also lacks a lot of profiles..

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Topcat is discontinued and doesn‘t (and mist likely won‘t) include the 748. it has good profiles for the 744 though. 

The 748 can calculate the perf data on its own using the EFB, however the PMDG version can‘t do this yet as the already digital data was much too expensive for PMDG (400.000$ p.a.). They do have the data on paper though and are working on implementing it into the EFB.

Until then you can simply use Flaps20 for normal take offs and Flaps 10 for strong crosswind or light airplane. A good value for a normal TO for a 10 hours flight out of EDDF is TO and 40degrees assumed temp, for a lighter plane you can easily go to 50 or 60 degrees. Or you use the EFB pretending high outside temperatures and checking if it says it‘s impossible. Then go to a lower temp. Until PMDG have finished this implementation we can‘t do much more than guess and play around with the temps. 

Last night I did a flight from CYVR to RCTP (12h40) with an airplane (748) close to MTOW and due to the snow I simply chose TO1 without bothering thr EFB too much. For now it works okay. 

But we were „promised“ to get an update for the queen the week after christmas, so maybe we are lucky and Robert is typing and preparing one of his pinned novels about it, including a completed EFB 😄 


,

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I can't speak to the de-rate as that often requires quite a bit of calculation.  However, the aircraft is quite powerful and it's pretty easy to get a big de-rate such as 40 degrees like Marc suggested.

 

For the takeoff flap setting,  a general rule with our aircraft anything above 700,000 lbs is typically a Flaps 20 takeoff, anything below that would be a Flaps 10.  There are certain exceptions, Flaps 10 provides for a better initial climb and thus obstacle clearance, while Flaps 20 generally shortens the time the aircraft is physically on the runway...so in certain cases based on the available runway we may choose something non-standard.

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-Jason Peters, MSgt, USAF Ret.
Charter Pilot (SIC). Citation II, V, Ultra, & Excel
Comm-ASEL, AMEL, IFR, & Flt Engineer-Turbojet

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18 minutes ago, rondon9898 said:

$400,000 per annum for performance data? Why??

Because aviation is expensive! 🙂

On a serious note - don't underestimate the cost to Boeing of generating that data in the first place, which will have involved significant amounts of flight testing for the data collection, as well as a lot of work from performance engineers, plus (if you're wanting the data needed for proper calculation) obstacle and terrain databases that need to be maintained, certified and kept up to date. Then there's the cost of certifying the data in the first place. None of this is cheap... the thing about real data is that it has to be right or else people die, and the process for ensuring that it is right takes a lot of expensive people a lot of time and the use of a lot of very expensive equipment (like flying real 747-400s).

Obviously in a sim the same standards do not need to be applied and there are tools like Topcat that use basic FCOM/QRH data to do the calculations to what I would suggest is probably a good enough standard for sim use... but people seem to complain that that's not good enough, so...

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Simon Kelsey

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To add to what Simon said: I have done some performance calculations during my study and your never at the specific weights there mentioning so your always trying to interpolate between figures. And that is the hardest part.


Koen Meier

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As a Flight Engineer, I kinda do performance calculations for a living.  A reduced thrust, takeoff data card, with obstacle clearance for the 747 is a full page long and can take someone who is entirely familiar with the process upwards of 30-40 min to compute manually using the performance manual... for each available runway or scenario!  Obviously, computer based performance software has greatly reduced both the required time and workload, but this software is incredibly expensive!  I've been working to procure a new version for our aircraft and it's upwards of $500k for the software plus a year or two of support, and thats with us providing our performance data and manuals directly to the developer!

This is not an easy task, and what PMDG has managed thus far is nothing short of outstanding.  I'm all for maxing out the available realism and procedures of my desktop sim, but at the end of the day it's just that, a desktop simulation.  It's intended to give you a highly realistic peek behind the curtain at what it's like to operate one of these magnificent machines, nothing more.  Perhaps some of these complex tasks are better left to our imagination...

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-Jason Peters, MSgt, USAF Ret.
Charter Pilot (SIC). Citation II, V, Ultra, & Excel
Comm-ASEL, AMEL, IFR, & Flt Engineer-Turbojet

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I think a peek into the complexities involved in aviation are a good thing, but at the end of the day when we are not focused on problem solving and just want to enjoy simulated flight there are work arounds that you would never do real world.

For ATM calculations, run your takeoff calcs in the EFB with wind, temperature, and flap setting and note the result.  Then change the OAT to an assumed temperature up to 60C.  I usually start with 40C and increase or decrease by 5 C until I get acceptable takeoff settings.  Now you have found a suitable ATM value for simulation purposes.

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Dan Downs KCRP

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1 hour ago, downscc said:

I think a peek into the complexities involved in aviation are a good thing, but at the end of the day when we are not focused on problem solving and just want to enjoy simulated flight there are work arounds that you would never do real world.

For ATM calculations, run your takeoff calcs in the EFB with wind, temperature, and flap setting and note the result.  Then change the OAT to an assumed temperature up to 60C.  I usually start with 40C and increase or decrease by 5 C until I get acceptable takeoff settings.  Now you have found a suitable ATM value for simulation purposes.

Thanks everyone for their informative replies! Learned quite a few.

 

@downscc, what do you mean by acceptable takeoff settings?Do you mean as long as you can take off with the current weight+flap setting and lowest thrust = acceptable?

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1 minute ago, mustiej said:

what do you mean by acceptable takeoff settings?Do you mean as long as you can take off with the current weight+flap setting and lowest thrust = acceptable

Basically, since the EFB is not providing distance required vs distance available.  Also this is just a rough estimate that does not take into consideration minimum climb requirements and obstacles.  It basically gives you an ATM value so you know you are covered for balanced field length and Vmcg limits.


Dan Downs KCRP

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