Auto throttle Behavior Question

[Wink207 78]

Hi all:

I wonder if someone could clarify an auto throttle question. I have read all the auto throttle threads and I understand how the MADDOG works here and the importance of a null zone on the throttle hardware. The question I have is this: at altitude when the auto throttle is in FMS speed or FMS over ride, the hardware throttles have no effect on the sim. I can move 'em back and forth with no effect. Much like the usual FSX auto throttle sim. However, on the take off roll as we've seen, after selecting auto throttle and TOGA, with the TRP in TO, the auto throttle is affected by the hardware, hence the need for a null zone. So as another poster mentioned, if we advanced the throttles to say 1.4 EPR, then select auto throttle, in my system the EPR will move up to the correct value for TO, but then move back down to wherever the hardware throttles ended up. So the choices seem to be to manually advance the hardware to the TO EPR, or just leave them in a null zone and select TOGA and auto throttle. So after all that smoke, my real question comes down to is this behavior a limitation of the sim, either FSX or MADDOG? Why doesn't the auto throttle ignore the hardware position in TO as it does in other modes? I haven't flown the NGX for awhile but I don't remember that type of behavior.

Thoughts?
Thanks

Rick

[Jovabra 18]

Same aircraft other flightsim but very interesting.

https://www.youtube.com/watch?v=-dEXtlkIhAY

There are 3 more instruction movies.

Regards
Jo va Bra

[Wink207 78]

16 minutes ago, Jovabra said:

Same aircraft other flightsim but very interesting.

https://www.youtube.com/watch?v=-dEXtlkIhAY

There are 3 more instruction movies.

Regards
Jo va Bra

Yes, thank you. I have been through these. In particular, if you review the departure video you will see that in the subject sim the throttles are manually advanced to 1.4, then auto throttle is selected and the EPR moves up to TO and stays there. That is not what I am seeing in MADDOG.

[thibodba57 462]

The reason your hardware is able to move the power levers during take off is the the Autothrottle system goes to CLMP or in Boeing speak HOLD.  It has the same function.  The servos in the AT system are disengaged thus allowing manual input when/if required without the AT system moving the levers immediately after.  This is accurately modelled actually and is why you need to move the hardware up into a nullzone.  The only time your hardware will override the AT is in CLMP as well.  FMS OVRD in Boeing speak is SPD INTV or opening the speed window.  The AT is still controlling the system the hardware on your end.  If you want to do manual Power Lever descent you would need to enter IAS MACH as your pitch reference mode which will place the AT system in CLMP.  This make it about as clear as mud? 

[Wink207 78]

3 minutes ago, thibodba57 said:

The reason your hardware is able to move the power levers during take off is the the Autothrottle system goes to CLMP or in Boeing speak HOLD.  It has the same function.  The servos in the AT system are disengaged thus allowing manual input when/if required without the AT system moving the levers immediately after.  This is accurately modelled actually and is why you need to move the hardware up into a nullzone.  The only time your hardware will override the AT is in CLMP as well.  FMS OVRD in Boeing speak is SPD INTV or opening the speed window.  The AT is still controlling the system the hardware on your end.  If you want to do manual Power Lever descent you would need to enter IAS MACH as your pitch reference mode which will place the AT system in CLMP.  This make it about as clear as mud? 

Actually, that helps a lot. Once in CLAMP the A/T system is out of the equation, presumably until lift off. So really there is no choice but to manually advance the hardware to TO EPR after CLAMP, or leave the throttles in a null zone and use A/T TOGA from the beginning of the roll. I'll check what happens if I advance the throttles to 1.4, kick in the A/T, and retard the hardware back to a null zone. When you say "move up" to a null zone, I don't believe FSX/Saitek would support that. I need to retard.

Thanks for the help.

Rick

[thibodba57 462]

6 minutes ago, Wink207 said:

Actually, that helps a lot. Once in CLAMP the A/T system is out of the equation, presumably until lift off. So really there is no choice but to manually advance the hardware to TO EPR after CLAMP, or leave the throttles in a null zone and use A/T TOGA from the beginning of the roll. I'll check what happens if I advance the throttles to 1.4, kick in the A/T, and retard the hardware back to a null zone. When you say "move up" to a null zone, I don't believe FSX/Saitek would support that. I need to retard.

Thanks for the help.

Rick

Procedurally speaking use of the TOGA to correct anything AT related is actually incorrect.  Thats another Boeingism.  Once I run my Taxi checks I press TOGA (you should be able to do this at the gate also) so entering the runway you should see BLANK | TAKOFF | TAKOFF on the FMA.  When you're ready for take off, power comes to 1.4 EPR then AT selected on.  This should push the power up to the selected EPR Reference from the TRP.  At 60 kts you should receive CLMP.  CLMPs use that this point among other things such as a rejected Take off (most important) is the ability to push the Power up to the EPR Ref marks yourself if the power didn't stabilize there prior to 60 kts.  Say on a really windy day.

If you have FSUIPC doesn't matter what hardware you are using.  You can create a high and low end Nullzone.  On take off I push my hardware up to the firewall as I'd rather deal with an overboost than an engine going to idle and on descent I bring it back as far as I can.

[Wink207 78]

16 minutes ago, thibodba57 said:

Procedurally speaking use of the TOGA to correct anything AT related is actually incorrect.  Thats another Boeingism.  Once I run my Taxi checks I press TOGA (you should be able to do this at the gate also) so entering the runway you should see BLANK | TAKOFF | TAKOFF on the FMA.  When you're ready for take off, power comes to 1.4 EPR then AT selected on.  This should push the power up to the selected EPR Reference from the TRP.  At 60 kts you should receive CLMP.  CLMPs use that this point among other things such as a rejected Take off (most important) is the ability to push the Power up to the EPR Ref marks yourself if the power didn't stabilize there prior to 60 kts.  Say on a really windy day.

If you have FSUIPC doesn't matter what hardware you are using.  You can create a high and low end Nullzone.  On take off I push my hardware up to the firewall as I'd rather deal with an overboost than an engine going to idle and on descent I bring it back as far as I can.

Ok, that makes perfect sense. And I do press TOGA at the gate before start, so I see blanf/TKOFF/TKOFF. One additional parameter is that I am usually light on TO, around 120,000 lb so what happens is I reach 60 kts pretty quick and CLAMP kicks in which either prevents the software throttles from reaching TO, or pulls them back to the hardware position. So I'll check out FSUIPC, which I have registered.

Thanks again

[thibodba57 462]

2 minutes ago, Wink207 said:

Ok, that makes perfect sense. And I do press TOGA at the gate before start, so I see blanf/TKOFF/TKOFF. One additional parameter is that I am usually light on TO, around 120,000 lb so what happens is I reach 60 kts pretty quick and CLAMP kicks in which either prevents the software throttles from reaching TO, or pulls them back to the hardware position. So I'll check out FSUIPC, which I have registered.

Thanks again

No worries.

[Bob Scott 7,716]

A more elegant, but time-consuming solution, would be to write a LUA script for a TOGA button that would first mask out the throttle axes, then engage TOGA on the panel, and keep the throttles masked (locked out) until they are moved a significant distance from where they were first masked.  I've done this in a few other airplanes (with C++ code rather than LUA, but the principles are the same).  This essentially establishes a null zone wherever the throttles happen to be at the time of engagement, rather than requiring them to be pushed all the way up or pulled all the way back to an end-of-travel null zone.

Regards

 

[Omaniac 3]

I have done absolutely nothing to my throttle settings. I advance, engage AT and thrust is set. From there on, nothing I do with my Logitech throttles affects the sim throttles. This last until I disconnect the AT and use them manually.

Isn’t there a setting for this in the Load Manager (or sim)? Allow throttle (or controls) to override sim throttles or something like that?

[el_kab0ng 29]

Hate to resurrect an old thread, but with the latest release of the MaddogX (1.5 b493), I'm seeing similar behavior with the AT on take off. With the Saitek hardware, I advance to 1.4, hit the AT and the throttle moves to the correct position, but eventually the throttle moves back to the position I left it in within the Sim, even though I haven't touched the hardware. There's some similar wonkiness happening with ILS and autoland. The throttles seem to go manual every time and don't ignore the hardware position as they should.