CTOT & Autocoarsen

[lonz1988 2]

Works nicely  🙂

Cheers

Lonz

Edited April 26, 2018 by lonz1988

[lonz1988 2]

It may be a placebo but is this even simulated? I dont seem to be achieving the power setting.

Lonz

[Guest JetFueler]

It doesn't appear (not surprisingly) CTOT is working.  CTOT is meant to maintain a desired torque setting on take off run counteracting the 'torque bloom' a turbo prop experiences as it's speed increases. This would require some rather advanced coding to simulate properly.  The default FSX/P3D autothrottle logic will only hold a fixed power percentage for TOGA or manipulate the throttles to maintain a desired speed.  Anything else, even as seen in the LES XP Saab, is coding wizardry.

[Fabs 15]

Hi,

I’m familiar with the LES SAAB in XP which features a working CTOT implementation. 

With this feature, I find that I can keep the engines at peak as you climb, whereas with the Carenado using full power for takeoff means that power can only fade as you climb. 

Clearly then my technique is incorrect; how do others here manage their takeoffs without CTOT?

Do you derate and if so how do you calculate, or do you firewall the throttles and then reduce for climb?

Just interested in how other manage power during ascent. 

Thanks,

Fabio

[Faelandaea 16]

I just hand select a power setting that keeps her from being fire-walled.  For takeoffs, and I do this in all aircraft, not just this one, I adjust the throttles to have power around 10% below the red line, then adjust back as I stabilize into the climb phase.  In the real world, I trust aircraft systems.  In P3D, however, I have found it better to just handle the throttles myself.

[Fabs 15]

Thanks, I appreciate the answer. 

A working CTOT system would be nice though. 

Fabio

[dbw1 445]

CTOT is also good for doing reduced power take offs. When I flew it this was recommended whenever possible and the company provided the charts for every runway we regularly used. Generally rule of thumb was there was next to nothing gained in engine life for doing a take off with power reduced below 90% tq so that was the minimum used. There were times I used 100%tq regardless of the charts but that was usually because i didn't like the over run area in case of a reject and not being able to stop...one was a lake right at the end of the runway. I haven't bought this aircraft yet as I'm hoping things like this will be added. One other thing about CTOT if I remember correctly as it's been 20 years since I flew one was that in the event of an engine failure during takeoff it automatically increased the power of the good engine by an additional 7% power. V1 cuts in the sim were interesting.

[Fabs 15]

Thanks, that’s interesting. 

I went as far as buying the Just Planes REX Airlines DVD (it was on sale) to get a better impression of this aircraft, and then the Viking Productions Estonian Airlines SAAB 340 but neither cover in any real detail their use of CTOT or power settings.

I was still none the wiser!

The Leading Edge Simulations SAAB 340A for X-Plane is awesome, and it has CTOT modelled, and is my go to turboprop in that platform.

I found this informative thread about CTOT, which one person describes as an elementary auto throttle!

I really do unstandard what he means when he says you never know whether you’ll get a torque increase or decrease when switching off CTOT.

In XP’s LES SAAB you bring the throttles up slowly beyond 50% (from memory) and you then leave throttles where they stand at the point where the CTOT mechanism takes over by metering in fuel to obtain the torque that you have dialled in.

When you switch off CTOT, where your throttles lie then becomes your climb power...OR NOT as often the power levers will be way too far back.

Does this sound vaguely right?

May I ask also roughly what sort of routes you flew, and also the loads and fuel carried - were you lightly loaded or at MAUW?

Thanks,

Fabio

 

Edited August 18, 2018 by Fabs

[dbw1 445]

The routes were anything from 11000’ of pavement in the Canadian prairie to 4000’ of gravel in the arctic. Lots of MTOW departures and less on quiet days or when the runway analysis charts dictated. At the time the company was not gps approach approved so lots of ndb and vor approaches where there was no ILS. The company had the prop brake option which was nice in winter with temps -30 to-40c before windchill.

[Fabs 15]

Thanks, very interesting. 

Didn’t know it had a prop brake option, presumably like the ATR. 

Fabio