JS41 Sevre Oscillations

[Guest Tamadeez]

Hi all I very recently decided to learn how to fly this bird and initial impressions was awesome. I did the start and takeoff part of the tutorial and during climb I found a very annoying problem. Now I'm 99% sure I have the plane configured. Using that handy T/O config button on FO side makes no alarms. So I rotate no fuss. Now the HDG and NAV works like a charm however the ALT , ALTSEL and IAS are causing problems. I assume ALT means hold current ALT because thats what it does after some oscialltions reaching + and - 2000FPM. Now switching to IAS just gives me oscillations. I actually see the FD going up and down making it feel like a rollercoaster. Not at all maintaing my IAS speed. And the ALT SEL doesnt appear to do anything. Appears white in EADI. Now ive tried with and without bank limit and soft ride on so I'm really stuck. I also tried setting RPM 98% adjusting thrust for nice EGT no help.

[MatzeH84 81]

Well, it's all explained in the manual.. but..ALT= Altidtude holdALT SEL= level of at the dialed altitude (then go into ALT mode)VS= hold selected vertical speed (speed may change)IAS= hold selected IAS (vertical speed may change)It's NOT the way that the AP controls the power to maintain the selected airspeed (you have to do this yourself, IAS mode is not autothrottle!). The only thing the AP controls in IAS mode is the pitch.

[Guest Tamadeez]

Well, it's all explained in the manual.. but..ALT= Altidtude holdALT SEL= level of at the dialed altitude (then go into ALT mode)VS= hold selected vertical speed (speed may change)IAS= hold selected IAS (vertical speed may change)It's NOT the way that the AP controls the power to maintain the selected airspeed (you have to do this yourself, IAS mode is not autothrottle!). The only thing the AP controls in IAS mode is the pitch.

... there must a be a misunderstanding because I know this. This does not explain the FD telling me to go up and down.

[Paul_Smith 92]

... there must a be a misunderstanding because I know this. This does not explain the FD telling me to go up and down.

Not being rude but you may know AP modes for Boeing or default aircraft, but this is neither. Try following the tutorial flight and if you still have questions the manual doesn't address, you will find people here very helpful. Unfortunatly, when you say you already understand something that your questions clearly suggest you don't, it becomes difficult to know how best to help you.

[trisager 2]

... there must a be a misunderstanding because I know this. This does not explain the FD telling me to go up and down.

Some examples of situations that will give you oscillations:* Climbing at 1,500 ft/minute and pressing ALT. You need to be in level flight, more or less, before using ALT.* Climbing at 200 kt, then pressing IAS with a target speed set to, for example, 170 kt. The aircraft will pitch up to reduce speed, get too slow, pitch down again, etc. You need to be close to target speed before pressing IAS.