I attempted to use TOPCAT to calculate TO.  The values given were almost identical to the default numbers calculated by the FMS. 

When I commenced TO using values for TO-1 52C derated, I would have gone off the end of RWY had I not advanced to TOGO.

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I have the same issue, and I also have the Boeing's offical performacnce software data and FPPM to back up that TOPCAT's data is mostly correct (it actually use the FPPM data).

Yesterday I takeoff on 752wP2040 from LGRP with 98.5T,Flaps5 and 48C ATM (FPPM shows I can go 52, but FMC only allow 48max), I used up the full runway (ther should be at least 15% margine for all engine takeoff)

Also the cruising EPR is about 0.1 higher than the manual. while FF is around correct value.

While the RR engine have faulty FMC ATM EPR cauculation (as I reported in bug report post), if use the correct EPR from FPPM, the takeoff distance and climb performance feels about correct.

Also I have tried the engine failure take-off at V1, the rudder efficiency is not enough to meet Vmca requirement, I have to give some aileron input and bank to keep fly stright, with about 15~25 of drift angle, even when speed are up to V2+10~20.
While CS757 is not designed for failure simultaion, it's quite easy to fix by change the rudder_effciency value in aircraft.cfg then (I use 1.3 but without strict test.

Thanks.  Glad I'm not the only one.  Here is a PDF of the TO values.  Forgot to include.

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One important thing I keep noticing people doing. On TOPCAT you cannot select the checkbox that says allow combination of both derate and assumed temp. It doesn’t work like that in captain sim. In CS if you select a fixed derate, “TO1” “TO2”, then you select a temperature, the derate is instantly cancelled and the EPR will be considering temperate only. Just like the real plane.

Nevertheless, there is an issue with their calculation and I hope they can fix it.

In my attachment, that box I circled should be UNCHECKED

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Dreamflight767 wrote on Oct 23^rd, 2020 at 4:47am:

I attempted to use TOPCAT to calculate TO.  The values given were almost identical to the default numbers calculated by the FMS.  When I commenced TO using values for TO-1 52C derated, I would have gone off the end of RWY had I not advanced to TOGO.

Also, with your margin of 593 feet, at my company that would not be enough of a margin. That short distance could be gobbled up almost from doing a rolling takeoff and non-SOP takeoff procedures. In TOPCAT I look for at min of 1000ft and by then I should probably be at a higher flap setting.

Alex T wrote on Oct 23^rd, 2020 at 9:59am:

Also, with your margin of 593 feet, at my company that would not be enough of a margin. That short distance could be gobbled up almost from doing a rolling takeoff and non-SOP takeoff procedures. In TOPCAT I look for at min of 1000ft and by then I should probably be at a higher flap setting.

The line-up distance used by Boeing and our company for -200 is 19m for TODA and 38m for ASDA, just about 100ft, and the rolling takeoff should have "negligible" effects about TOD as FCTM.
And the TOD here shown is for Engine failure at VEF(1s before V1), OR, for all engine*1.15. AND, for airborne to 35feet, that's quite some margin for you to actually overrun the runway....

Angel of Attack wrote on Oct 23^rd, 2020 at 12:42pm:

Alex T wrote on Oct 23rd, 2020 at 9:59am: Also, with your margin of 593 feet, at my company that would not be enough of a margin. That short distance could be gobbled up almost from doing a rolling takeoff and non-SOP takeoff procedures. In TOPCAT I look for at min of 1000ft and by then I should probably be at a higher flap setting. The line-up distance used by Boeing and our company for -200 is 19m for TODA and 38m for ASDA, just about 100ft, and the rolling takeoff should have "negligible" effects about TOD as FCTM. And the TOD here shown is for Engine failure at VEF(1s before V1), OR, for all engine*1.15. AND, for airborne to 35feet, that's quite some margin for you to actually overrun the runway....

Yeah I agree it’s “safe” if it returns takeoff data, not familiar with Boeing software or what TOPCAT uses in the background as aerodata / sabre are all I’m familiar with. Just stating 600ft in a simulator considering how some flight simmers do things procedure-wise, may seem like an almost  overrun to simmers. Especially when runway lengths in FS don’t always match real world lengths. But again, of course the TO thrust simulation is off in CS, that’s the main point.

Any news on this again? My takeoff performance calculators are still giving me much higher EPR values for a given assumed temperature.

Another thing I noticed is the target TO EPR will decrease with speed growth, I know it will be ture if N1 is fixed or if it's a fuelflow controller engine, but not sure how it should be for EEC engine like 757's. But I would assume the EEC would keep EPR constant.

For most weight I have, the ATM temp can even push the TO EPR at about 180~200kts to be lower than CLB2 EPR when it switches, even when the TO EPR at stationary are higher than CLB one. It can't be set lower than CLBx one as TMC setting, but on CS757 this only apply when stationary.

Angel of Attack wrote on Dec 10^th, 2020 at 8:01am:

Another thing I noticed is the target TO EPR will decrease with speed growth, I know it will be ture if N1 is fixed or if it's a fuelflow controller engine, but not sure how it should be for EEC engine like 757's. But I would assume the EEC would keep EPR constant. For most weight I have, the ATM temp can even push the TO EPR at about 180~200kts to be lower than CLB2 EPR when it switches, even when the TO EPR at stationary are higher than CLB one. It can't be set lower than CLBx one as TMC setting, but on CS757 this only apply when stationary.

After watch some cockpit video, I'm sure my assumption is correct: EEC should keep EPR constant at the whole TO run

This definitely seems a problem to me too, the numbers seem correct but the aircraft just doesn't seem to accelerate quickly enough and you can go off the end of the runway! Seems to be the same on the 767 as well.

I do love the addon and would use it more if this were better tuned.

Could Captain Sim comment?