Cessna Citation Longitude's autothrottle does no more hold the cruise speed

Sim Update 15 Beta Aircraft & Systems
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1

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Are you using Developer Mode or made changes in it?

No

Which aircraft are you using that experiences this issue?

Cessna Citation Longitude

Brief description of the issue:

Autothrottle does no more hold the cruise speed

Provide Screenshot(s)/video(s) of the issue encountered:

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Detailed steps to reproduce the issue encountered:

As shown on photos i set everything and autothrottle on.

Before this update the Longitude maintained the assigned cruise speed with auto throttle on, now it loses speed, and i am at right altitude!

PC specs and peripheral set up:

Xbox Series X controller

Are you using DX11 or DX12?

No

Are you using DLSS?

No

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Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

Are you using DX11 or DX12?

Are you using DLSS?

If relevant, provide additional screenshots/video:

2

If your climb rate is at max speed, I’m not sure how that works. Climb rate is supposed to be at a speed less than max cruise - if you expect to climb at any reasonable rate beyond 800-1000 FPM.

You can either climb at Best Angle or Best Speed for Pitch. Angle gets you a higher Climb Rate up until a certain altitude. Then switching to Best Speed is more effective.

But neither one of those is at M0.82.

3

Well the other phases the autothrottle works as scheduled, the problem is in the cruise

4

I climb at average 800-1000 fpm

5

For climb, are you using FLC?

6

Yes, normally i do, but also, rarely, i use VS, but rarely, and both of them have the autothrottle maintaining the assigned and scheduled VNAV profile (climb and descent), the issue, and this with this update, is on cruise. Before this update i assigned a mach speed, 0.800 or 0.820, usually, and it maintained them both.

8

Well, I can say with authority this is not a bug.

I’m just flirting with barberpole redline line Vne.

Now it took 6-7 minutes after leveling off at M0.76 climb to get to M0.84, but we are there.

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Here’s my climb and cruise profiles.

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You’ve borked something in your VNAV customization I think. Either that, or you have way too much anti-ice on in your settings. And why the fuel cross-flow? Those CAS messages are probably part of the reasons I think.

1 Like
9

Thanks for your info, but i don’t think it was due to that, since before this update, whatever VNAV datas i set from climb to cruise and to descent, the plane and its throttle followed everything and i was to consider this aircraft the most precise of the whole sim. I always set 200 kt below 3000 ft, 250 beliw 10000, 310 and mach 0820 above 10000 in climb, then mach 0820 in cruise, and mach 0760 followed by 250, yhen 250 below 20000 ft and 140 below 7000 in descent. Every thing was perfectly followed. Usually i climb to 45000 ft, its altitude, some time also 50000. To reach the altitudes more efficiently i push forward the throttle manually and activate the auto once at cruise altitude.
All followed perfectly by the plane.
Now this problem.

Present build 1.37.13.0

10

Your VNAV profile use is part of the issue. Let the jet drive itself. Reset your profile and don’t insert any speed constraints. It’s working correctly as I showed above.

Manual throttle management is inefficient compared to the FMS and FADEC working together to optimize the engine power curve as you approach maximum ceiling which is FL450. There’s a reason why there is a default VNAV Climb Profile set to M0.76. Flight testing from the manufacturer dictates that’s the best speed for climb. Go any faster than that, and you just take longer to get to altitude and you burn more gas needlessly.

11

Uh, i am curious about, so i will follow your advice. Tonight i will fly Longitude following default VNAV, and by the way, as i set the waypoints along the flight route you sayd to not write the speed constraints, did i understand well?
Might i insert the altitude constraints, in other side?

12

Sure, you can apply altitude constraints. Just be aware that if they end up crossed out, it means there’s something wrong with the waypoints - as an example, they might be too close to each other to fly that path safely no matter what speed you use.

13

Thanks greatly, this info of yours is one of the most important: defacto, i never understood the reason why i saw the altitude constraints crissed out, until now that i received ths answer, thanks to you now i have gained an ulterior knowledge on constraints management, my best thanks and wishes for you.