Thrust handling



  • I have a question regarding correct thrust handling, especially for climb power. I am not sure if I operate it correctly or it doesn't work as expected due to misunderstanding.
    Before takeoff, N1 93.7 and Temp 840C as advised on the TMS. Now for takeoff I increase thrust slowly to the max and weight until TMS takes over and sets this to 93.7. So far so good.
    Then reduction to climb power. If I understood it correctly, there are two ways to do that. One is the SYNC method, the other the TGT method. No matter which one, what I get is a thrust increase, not a reduction. E.g. after pressing sync the number on the TMS display jumps to 99.9 (which I assume is N2 then). However, that leads to N1 going up to 96% (N2 above 100), which is a thrust increase !
    If I only barely move the throttle manually out of max, the N1 goes down to the 75-80% range, which can't be correct either.
    What am I doing wrong, or might have misunderstood ?

    Mike


  • JF Staff

    Hi Mike,

    Pages 148 to 152 and 237/238 cover the TMS so worth giving those a read. It's not the most obvious system!

    Sync mode does not provide a managed thrust setting, it just allows you to set the desired thrust manually using either engine 1 or 2 (depending on the MSTR setting) and the TMS will adjust the other three engines to match that thrust setting - either N1 or N2 depending on the CTRL setting.

    From the real-world videos that I've watched, they will often stay in TO mode during the climb out and then switch to SYNC and manually set the N1 using engine 1 to achieve the desired climb performance. That provides control over both thrust setting and TGT.

    The CTRL annunciator on the TMS will indicator whether it's N1 or N2 being used at the time SYNC is engaged. It automatically switches from N1 to N2 if the N2 is less than approx. 70%.

    You will see a jump in the N1 ref when selecting SYNC as it's now displaying the commanded thrust setting on either engine 1 or 2 (depending on the MSTR setting).

    Hopefully that makes some sense and there are a few RW pilots on the forum so I'm sure they'll be able to share their tips for the TMS.



  • @Martyn

    Hi Martyn,

    Ok, thanks for the clarification. So I need to set the thrust manually. However, as I mentioned, just moving the throttle barely out of max on the throttle lever of my stick (a new Thrustmaster TCA) leads to thrust getting reduced drastically. Maybe a problem of the stick then ?!

    You will see a jump in the N1 ref when selecting SYNC as it's now displaying the commanded thrust setting on either engine 1 or 2

    that's what I don't really understand. Why an increase in N1 when dealing with reducing thrust with climb power ? Page 241 in the handling notes has this TMS info :

    Climb power may be set in either of two ways:
    1. N1 SYNC mode

    • CTRL button N1
    • MSTR button As required. No.2 engine is normally selected as the master engine to minimise
      directional trim changes during power adjustments and to enhance
      synchronisation of the inboard engines.
    • SYNC button Press – confirm SYNC mode lit

    Doing that, I get an N1 increase from 93.7 to 96.2% shown on the TMS display.


  • JF Staff

    If the TMS has reduced thrust whilst in TO mode (e.g. if max thrust has been set using the levers) then switching to another mode will cause the TMS actuators to return to neutral, resulting in the thrust setting returning to that set by the levers - which in the case of them being fully forward will probably be a higher N1/N2 than was commanded by TO mode.

    We'll investigate in case that behaviour needs to be tweaked.



  • @Martyn said in Thrust handling:

    then switching to another mode will cause the TMS actuators to return to neutral, resulting in the thrust setting returning to that set by the levers

    Hm, that also is not easy to understand. If you have the throttle levers on correct N1 setting for takeoff and you click SYNC; then it would have no other chance than to read that setting from the levers. In that case you would just copy the current "thrust lever" N1 to the TMS, but you would have no chance to get a lower setting for climb ?
    Or would be the procedure to reduce thrust with lever first to a climb setting you guess, then click SYNC and then readjust throttle to the value the TMS calculates ?

    Sorry for the many questions, I'm just more and more loving the aircraft and try to understand and fly it correctly. It is not hard to notice a lot of dedication and passion went into that project on your end !

    Mike



  • @Mikealpha Hey man, to the best of my fading memories of the 146 this was how the TMS was setup and used on the initial stages of a flight:

    Preflight
    -When the ATOW is known the crew can determine the following:
    -N1REF with respect to airfield and icing conditions. I believe JF have included the chart to determine this?
    -N1FLEX Using a runway specific chart a flexible temp is determined (if a rated takeoff is not required).
    I'm not sure if there is data available to simmers to determine this for the 146. Something like the TOPER product for the
    Boeing stuff would be great to have. I'm guessing in this day and age IRL, the above is completed using an EFB product...

    -On the engine N1 gauges, N1FLEX (if used) would be bugged on the engine nearest the pilot flying and N1REF on the 3 remaining gagues.
    -The TMS is bugged with the required reference temp (OAT for rated or flex temp as required) and company EGT limit of 800 is set.

    Takeoff/Climb
    -When lining up or back-track is completed the TMS is switched on and TO mode is selected, PNF calls the displayed N1.
    -N1REF or N1FLEX is set by 70kts

    -At acceleration altitude (normally 1000AGL for NADP1) climb power is selected. Company procedure was to select TGT with a setting of 780c used unless an early level off was required in which case sync was used.

    -If a higher N1 flex was used for takeoff used it was pretty much equivalent to climb power so could be maintained for the initial climb. Especially to clear terrain or icing etc.

    Climb power should come with a reduction in power but not necessarily a drastic one. From my experience using the 146 pro so far I see a sensible reduction in thrust when selecting climb power. I do however get some really high EGT's when starting engines in OAT's above 15 degrees!

    I hope that all makes sense as a quick overview. Please shout if I've missed something!

    Cheers,

    JL


  • JF Staff

    @Jumbolino said in Thrust handling:

    I do however get some really high EGT's when starting engines in OAT's above 15 degrees!

    We're working on a fix for the high EGTs.



  • @Jumbolino said in Thrust handling:

    First of all thanks a lot for the explanations !

    Climb power should come with a reduction in power but not necessarily a drastic one. From my experience using the 146 pro so far I see a sensible reduction in thrust when selecting climb power.

    how exactly would you select climb power using SYNC on the TMS ? I am still not sure how to do that. If I use the SYNC method as mentioned above, I just get the current N1 copied to the TMS display (as Martyn explained)

    Mike



  • @Mikealpha Try hitting TGT then SYNC. I believe this will give you TGT SYNC mode. Just make sure you have a sensible EGT (780 should work) selected in the scroll wheel window.



  • @Jumbolino said in Thrust handling:

    @Mikealpha Try hitting TGT then SYNC. I believe this will give you TGT SYNC mode. Just make sure you have a sensible EGT (780 should work) selected in the scroll wheel window.

    That didn't make a difference. I still get just the actual N1 value copied to the display. Doesn‘t really make sense.


  • JF Staff

    If SYNC is engaged (pressed) with TGT already engaged (as indicated by the green arrow) then TGT SYNC mode will engage and the selected TGT is displayed rather than an N1 ref value. It's working here:

    TGT_SYNC.JPG



  • @Martyn hallo and , first-things-first, thanks for giving us the best PC based BAe146 reproduction so far!!
    I’ve Flown the real “Quiet Trader” more than 20 years ago ...so please accept my apologies for my very “Fading memories” ( as “Jumbolino” used to say😅) on what I’m going to post in this forum.
    Anyway the aircraft, as mentioned above, is really accurate but I’ve found a little strange there is no way to find a good resource for “Flex T/O”. Toper works only for Boeing Aircraft and TOPCAT has no BAe 146 options as well😓😓😓😓....it would nice if you help us find a reliable resource for this. I mean, this aircraft “works-around” the TMS. And Flex operations are now used on 90% of departure procedures. It’s really a shame such a good add-on cannot use it.....sorry to point it out but, almost all the others add-on I’ve been using can easily use flex temp take-off and climb ( PMDG,FS Labs,MajesticSoftware ...only to name fews..).
    Thanks for your support.
    Regards,
    Claudio


  • JF Staff

    @Mistral2000 said in Thrust handling:

    Claudio

    Hi Claudio,

    There is information and tables for the TMS, including flex, in the handling notes of the manual. We can add more information if you feel there is anything missing.

    Thanks
    Martyn



  • Hi Claudio (@Mistral2000), as well as the tables in the JF manual, there's various tools available online such as the freeware Universal Take Off Performance Calculator (UTOPIA) tool. It's not specifically designed for the JF 146 but it does contain type-specific de-rate data based on given runway, aircraft weight and weather conditions. It's pretty reliable and it's free - you can pick it up from various library websites such as Avsim.
    Cheers,
    Craig



  • @Martyn hallo!
    Martyn I’ve digged into the manual and on the “Handling Notes” there are a lot of useful tables/graph as well as explanation.
    The point is different: on page 239 and 240 there are two very handy tables which help pilots finding N1 Ref and , eventually, a “Delta” N1 Felx. That is good but , the most important calculation I did when I was flying in the ( real..) BAe146, was finding the “Flex Temp” to insert into the TMS. The only way to find it is using “Runway Analysis or/and Flex Temp Performance Tables”. Since I use to operate the BAe146 on big/long runways I only used Perf Tables in relation to my ATOW and Aiport Weather infos ( Temp , Wind, Precipitation etc..). The best thing would be the so Called “Runway Performance Analysis “....ok Nowadays we have EFB....but “back-in-the-days” we had only “Papers” to work with....👍 if you like , to be more clear I can update to you some Runway Analysis Tables I used in the B737 Classic which was the last aircraft I’ve flown without the EFB....