Blackbird Sims / Milviz Forum Archive

I have just purchased the milviz and my autothrottle does not hold the speed, it will continue to increase speed until overspeed or it will decrease speed until it stalls. Anyone ever have this issue ?

Which autopilot are you using?

If it is the SP-177, please confirm the following:

Flight director on
Auto throttle armed and SPD mode engaged, not LVL CHG or EPR hold

Hi I can confirm it's the 177 version and yes I have flown Ngx for many years and I have fd on fms set lnav set and autopilot on with vertical speed selected. I don't understand why I am having this problem.

This isn't the Ngx mate. It's much MUCH older and balky system.

Yes but surely the auto throttle holds the speed.

You put on both flight directors? Just double checking.

my setup on departure is both FD's on Auto-throttle armed lnav engaged or hdg select engaged. once flaps retracted i then engage the auto-throttle and auto pilot. I use vertical speed for the climb and the auto-throttle tends to just bypass the selected speed and continue to increase speed. its more noticeable in cruise as it will continue to rise until i turn it off and back on again then it will decrease speed until it goes below the speed i have selected so i turn it on and off again and it will raise the speed again. it is slow enough but it means you cant leave it alone for too long or else it will be over speed or underspeed.
i use p3dv3

https://www.twitch.tv/eire1994/v/115166506

I just made a quick example of how i cant control the speed plus my startup/setup

Ok I watched your video and the auto throttle is behaving as expected. You had your engines at absolute max power rather than using a derated power setting and as a result you overshot your speed mark considerably. When you engaged speed hold, the autothrottle moved your throttles back and the engines spooled down. You didn't allow it much time to actually recapture the speed though.

Okay I appreciate the advice and I will play around until I get the hang of it.
On a separate note, is there a way of making the fms weights kg rather than lbs.

I just purchased this aircraft yesterday and I am having the same problem with auto throttles not working. I have a Saitek X-52 controller. During climb out I engaged both flight directors and set the auto-throttle speed and the airspeed overshot. I reduced my Saitek throttle and tried again with the throttle about half way up (50%). Same issue. I also had the speed hold selected. After level off I tried again after turning off the auto throttle and manually adjusting to hold the speed. Re-engaged and it did not hold the speed. I tried again and when I lowered the speed setting from 250 to 200 I could hear the engines spool down. I watched as the airspeed dropped and continued to drop below 200 knots. At 170 knots I turned it off and manually adjusted my throttle. The same configuration, both flight directors on, speed dialed in set to 200 and the speed light lit with auto-throttle turned on.

Auto-throttle?

Never mind. I tried again and this time everything is working. Don't know what went wrong the first time but second time is the charm.