Jump to content

FLEX Temp after engine start


Nicco54

Recommended Posts

I think I figured it out. On Perf page 2/3 you have to enter ISA. By default its set to +32. I change that in Celsius only for some reason? ex. I enter +20 and it converts it to enter an ISA value of 68 Fahrenheit. Then I can enter a flex temp (also only in Fahrenheit, ex. 90 flex) and flex is now working. 

Link to comment
Share on other sites

Strange that it would have that effect, that input should only really affect cruise and holding performance calculations (in the real plane). 

 

It is not actually ISA you are telling the FMS, but ISA deviation. So the 0C/32F default is correct in that the plane will assume ISA conditions. Entering 20 in that field would tell it that you expect ISA temperature plus 20 degrees Celsius on top. As far as I know, this should really not impact flex input. But at least you got it working :) .

 

Could you try perhaps to change it, set the FLEX, and then change it back to the default to see if it has any effect on the FLEX you just set? Just curious.

Link to comment
Share on other sites

A user of the Microsoft Flight Simulator Forum has attached this screenshot.

From the engine model it is for the CRJ900, maybe also CRJ1000.

Is this helpfull in the Flex discussion?

 

Please login to display this image.

 

I set mostly AT 30, ActiveSky gives me the Temperature at flightlevel and I calculate the ISA dev. 

AT30 covers a wide temperature range.

On my side the CRJ climbs as they should do.

Link to comment
Share on other sites

It is really a matter of personal preference in the sim, since there is no access to everything needed to calculate proper assumed temperature (flex) v-speeds. The proper calculation includes considerations for runway length available, obstacle clearance, climb requirements and even maximum tire speed. These might all impact your V-speeds. So whatever you set in the sim, you will probably have V-speeds that are not accurate. At that point you are choosing whether you want to simulate putting in FLX temp but incorrect speeds or correct speeds and no FLX temp, so it is up to what you prefer for your sim experience.

 

All a bit going into details of course. For example, the table you show is for sea level pressure altitude. It is one of about 9 tables ranging from -1000ft to 10.000ft pressure altitude. And another nine for packs on :P .

Link to comment
Share on other sites

4 hours ago, Hoffie3000 said:

A user of the Microsoft Flight Simulator Forum has attached this screenshot.

From the engine model it is for the CRJ900, maybe also CRJ1000.

Is this helpfull in the Flex discussion?


 I had posted this screenshot coming straight from my manuals and I'm guessing someone copied and pasted it in the MSFS forum. This is for the CRJ 1000 but it's not what we actually use to determine the FLEX needed for takeoff.

Link to comment
Share on other sites

FLX Temp only affects TO thrust. After you have entered a valid temperature, the N1 thrust indications on the EICAS are displayed in magenta and the target thrust changes from "TO" to "FLX". When you advance the thrust levers to the TO detent the FLX reduction is automatically applied.

Link to comment
Share on other sites

  • 1 month later...

Am I the only one not seeing flex temp being applied when the thrust levers are moved to TOGA? I input the flex temp in the VNAV page and see the reduced thrust being applied on the EICAS, but during the takeoff roll the power exceeds the pink targets. It's almost as though it's entirely ignoring the FLEX setting.

 

In the example below, the FLX target is 85 during taxi, but after advancing the throttle to TOGA, the thrust reaches 89.9% by the time I'm through 100 knots.

 

Please login to display this image.

 

Please login to display this image.

Link to comment
Share on other sites

4 hours ago, amahran said:

Am I the only one not seeing flex temp being applied when the thrust levers are moved to TOGA? I input the flex temp in the VNAV page and see the reduced thrust being applied on the EICAS, but during the takeoff roll the power exceeds the pink targets. It's almost as though it's entirely ignoring the FLEX setting.

 

In the example below, the FLX target is 85 during taxi, but after advancing the throttle to TOGA, the thrust reaches 89.9% by the time I'm through 100 knots.

 

 

Please login to display this image.

Same here 

Link to comment
Share on other sites

  • 1 month later...
On 6/19/2021 at 8:37 AM, FSHomeCockpit said:

I've found with flex entered and enabled there is no flex detent in the throttle so actually matching n1 flex with the throttles is quite hard to do. 🤷🏼‍♂️

When a flex temp is entered, the FADEC will command that at TOGA similar to Boeing aircraft. 

Link to comment
Share on other sites

  • 3 months later...
On 8/14/2021 at 11:00 AM, amahran said:

Am I the only one not seeing flex temp being applied when the thrust levers are moved to TOGA? I input the flex temp in the VNAV page and see the reduced thrust being applied on the EICAS, but during the takeoff roll the power exceeds the pink targets. It's almost as though it's entirely ignoring the FLEX setting.

 

In the example below, the FLX target is 85 during taxi, but after advancing the throttle to TOGA, the thrust reaches 89.9% by the time I'm through 100 knots.

 

 

Please login to display this image.

 

 

Same issue, not working for me.

 

Aerosoft - do you plan to address this issue?

Link to comment
Share on other sites

  • 1 month later...

The FLEX temp is taken into consideration BUT...the CRJ overshoots it then settles on the derated N1. This is a BUG already aquainted (in other threads). It is on the list and and we hope it gets fixed soon.

Link to comment
Share on other sites

21 hours ago, GEK_the_Reaper said:

The FLEX temp is taken into consideration BUT...the CRJ overshoots it then settles on the derated N1. This is a BUG already aquainted (in other threads). It is on the list and and we hope it gets fixed soon.

where can we see "known issues" like this?

Link to comment
Share on other sites

  • 2 weeks later...
On 3/11/2022 at 2:17 PM, GEK_the_Reaper said:

There is no bugtracking list on the forum.

Oh, I'm well aware of this as are others.

 

A better question might be...is there even an internal one? ...

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Privacy Policy & Terms of Use