[SOLVED] CTOT

[tryanc]

Thanks for an incredible plane. Having a blast learning to fly her.

 

One issue I am having is with the CTOT. I've carefully followed the checklists and flight tutorial, but during the takeoff run I'm unable to get the CTOT to engage. Its armed and set to 108% as stated in the manual. I carefully advance the throttles past 64% (and don't touch them once they reach this torque setting) but the CTOT doesn't increase them any further. So I'm stuck having to manually set takeoff thrust.

 

Any suggestions? Thanks in advance.

[pcartier]

Same problem here, could never figure out how this works

[AtomicFrawg]

You need to turn the knob to 108% then arm the CTOT. Also I found you have to push the CL's to the white bar on the TQ pop up. They seem to engage there. I think its 74%. anyway that's how I got it to work.

[Litjan]

The power levers not only need to be over 64%, they ALSO need to be within a certain range of the set torque (25% iirc). I believe this is done as a safeguard, so that the engines don´t suddently roar to full power if you accidentially advance the levers a bit too much while taxiing.

 

So after setting the desired torque and arming both CTOT switches you need to slowly advance the powerlevers until you can see the torque moving up towards the target level "all by itself".

 

It works best when moving the levers slowly - if you slam them forward you might end up very close to the desired level, and then the effect of the engines holding that autonomously isn´t very pronounced.

 

You wil also see that you were in CTOT mode when trying to reduce power after takeoff. The torque seems to "stick", until the levers are out of that 25% range, then the power snaps back. Thats why the correct procedure is to disarm the CTOT switches first.

 

Jan

[tryanc]

Jan, thanks for the reply.

 

I am aware that the power levers need to be within a certain range of the set torque. Even when I very slowly advance the power levers through 64% and slowly continue increasing it past this percentage, at no point does the CTOT take over and advance the throttles for me. For instance, even with CTOT set to 108%, I could slowly advance power levers up to 80, 90, 100 percent and they will remain there. Nothing "sticks" or takes over.

 

Is there anything else that could be interfering with this? Could my joystick be overriding the throttles? I am just using a plain old Logitech extreme 3d pro.

[Litjan]

I don´t think its the joystick, as the engine controller will start setting the torque without regard to the power levers.

 

You have the CTOT switches in "arm"?

 

The condition lever is in the high power regime?

 

Oh, and don´t look at the powerlevers - they will not move. Just look at the torque on the engine guages. Don´t confuse powerlever angle with torque (although they both count in %).

 

Jan

[tryanc]

Yes, CTOT switches are set to arm. Condition levers are set to MAX.

 

CTOT doesn't take over. I realize that the power levers won't move. But there is no torque increase.

 

Really stumped here.

[Litjan]

Really stumped here.

 

Me, too. Will see if I can find the time to do a tiny youtube movie on how I engage the CTOT and maybe you can spot the difference in what we are doing.

 

Might take until Wednesday, though, still away from home flying...

 

Jan

[JGregory]

Another consideration regarding CTOT... power for the CTOT (control) is from the (respective side) "Battery Bus".  Don't be fooled by the name. In order for that bus to be powered you need the "Generator Bus" to be powered.  If you are using Auto-Start then this should all be set properly.  If not, make sure that your battery switches are on and you have "reset" the generators (after engine start) so that they are "on-line".  Without Battery Bus power CTOT will NOT work.

[chaps]

CTOT perfectly works as stated for me, I set the rotary dial for 110% and set the arm switches. When I reach 70% or so CTOT takes over. Do you have ANY lights on the overhead panel during take-off? You shouldn't. 

[tryanc]

I did a fresh install of the Saab and the CTOT is working perfectly. Not sure what corrupted things, but thank you all for the help!