I am currently trying to learn how to fly the JustFlight Avro RJ Professional (I say trying because getting out of PMDG 737 mode is rather difficult for me, and adjusting to change is not one of my strengths). I have managed to get airborne after programming a simple circuit on the FMS, but the aircraft starts to pitch up and down as I slow down and descend. I assume that this must be because I am doing something wrong, but I do not know how to resolve it.

Can anyone help?

Can you detail what you are doing and what modes used while slowing and descending.

Christopher, ICYMI.  The first of a set of tutorials for the RJ.  The entire series can be found on the JF YouTube Channel.  Good luck.  This plane is a blast to fly!

-B

 

Yes it would be helpful to know what autopilot modes you are using.

Unlike its predecessor the Bae-146, the RJ does have a decently advanced autopilot.  You can use auto throttle and LNAV similar to a 737, the biggest difference is there is no VNAV (despite the existence of the VNAV button on the autopilot panel!).  You’ll need to use vertical speed or speed hold mode (adjust climb rate to maintain a set speed).

 

I have LNAV active during the short cruise phase, and I use LVL CHG to start the descent at T/D. My speed is 200 knots when I start descending, and I usually slow down to 160 knots after turning onto base (which in my case is about 12nm from the runway). I also have auto throttle engaged until I am on final approach at around 1500 feet.

Edited January 23, 20251 yr by Christopher Low

Does anyone know why the plane is pitching up and down during the descent and slow down from 5000 feet?

Not sure I have experienced that issue with the RJ. You mentioned having AT on. I normally keep everything manual except for ILS approach etc. Is pitch up/down slow or fast?

Several seconds for a complete pitch up and pitch down.

You might not want to hear this but every new plane I use I spend several flights entirely in manual control including at so I can learn the precise behaviour before applying any auto flight. 

At the very minimum I do a few circuits first. After doing that you can judge way more accurately what's going right or wrong with the ap logic. Some older (classic) planes just fly better with manual roll modes for example as the GPS wrecks VOR LOC. 

You'll need those manual circuits to get the feel for pitch during throttle and trim changes for sure. 

7 hours ago, Christopher Low said:

Does anyone know why the plane is pitching up and down during the descent and slow down from 5000 feet?

How much is it pitching up and down (ie degrees?)

I haven’t seen this before, I typically find the autopilot quite solid, so there must be something else going on in your case.

Have you tried reinstalling the aircraft?

Edited January 25, 20251 yr by regis9

I have not tried that, but I will if I am not offered any other solutions

This up and down can be a result of turbulence.

if you use Ma Realturb in FS2024 then you must update it. 
the old version have a bug with Mist, fog and cloud turbulence.

so it can Happens the plane. get out of control.

CG is not within limits.

5 hours ago, Torkermax said:

CG is not within limits.

Then why is the plane not bouncing up and down during the climb and cruise phases? It is rock steady at those times.

do you descend in FLTCH or in Sinkrate-Mode?
When you are in FLTCH Mode the computer did fokus in Speed. when you fly in different windspeeds, or turbulence,
so the computer did correct the speed always, what makes changes in sinkrate.
And this changes you will see in up and down changes.

When you are in sinkrate-Mode the your Fligtcomputer will hold the sinkrate fix, what makes the speed different, you will see changes in the speed.
 

Edited January 26, 20251 yr by Alti