[I assume Thomas will reply anyway, but I want to check I have this
right (from using the PMDG 757/767/777s which are supposed to be just
about the most accurate systems models out there)]
On Wednesday, May 29, 2002, at 02:23 pm, Jim Wilson wrote:
>
> So if in SPD mode the selected speed was too high, the autothrottle
> would
> still cut off at the max for whatever mode. Are the CLB and CRZ preset
> to a
> given thrust? And CON is that preset to the max rating of the engine
> or is it
> adjustable? Finally what is "TO/GA"?
On the FMC, one of the pages is THRUST LIM (actually there's a couple).
This is where you select TO/GA, CLB and CRZ power (as EPR values). I am
assuming (hopefully Thomas will correct me) that the auto-throttle picks
the 'limit' based on these settings. TO/GA, btw is Take Off / Go Around
thrust. It warrants a button of it's own (on the center pedestal, behind
the throttles, I think) that activates this power setting (presumably
one less thing to worry about when the crew is busy enough...)
For an automatic take-off, the procedure in the PMDG manuals I have is
roughly as follows:
(have the various LNAV / VNAV modes armed, and the auto-throttle
enabled on the MCP)
manually advance the throttles to start the take off roll (while
holding the bakes as required etc)
at 80% N1, engage TO/GA thrust (button in real life, Ctrl-Alt-F12
in Fly! 2, I think it's Ctrl-Shift-G in FS2k2)
from this point on, the auto throttle should maintain the specified
take-off thrust setting
Note the point here is to use a de-rated take-off EPR to save expensive
engine maintenance, as far as I can remember. When doing a manual take
off, I habitually bang the throttle slider on my joystick (which has a
very ligth feel anyway) right up to the stop. This is bad on all kinds
of levels .. the engine's N1 and EGT regularly go 'red', for example.
>
>> * ALT HOLD will maintain the current altitude by adjusting the pitch.
>> The
>> autothrottle will go to SPD mode.
> SPD mode at current IAS?
>
>> * FLCH is the most common Mode for climb/descents. In this mode the
> Thank you for this description. This is very helpful.
Yeah, I really need to start using it more in Fly! 2 .... it makes a lot
more sense now. I really wish I could find a joystick with a
servo-throttle, since without it a THR HLD mode is rather hard to
simulate. Come to think of, this probably explains why my descents in
Fly! are always way too fast (err ... i.e rate of decent is too
small) ... my throttle is still at some flight setting, so as soon at
the auto-throttle goes from IDLE -> THR HLD, it's going to jump right
back up.
One thing I'm noticing ... a modern jet auto[pilot | throttle] really
works better when it has an FMC to talk too :-)
H&H
James
PS - I just realized, anyone who has no idea what 'PMDG' is should
probably check out http://www.precisionmanuals.com/
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