[jhb_airlines] Re: Autopilot Help Please

  • From: "Alex - Reheat.org" <Alex@xxxxxxxxxx>
  • To: jhb_airlines@xxxxxxxxxxxxx
  • Date: Sat, 04 Nov 2006 16:05:11 +0000


I fear I'm not going to help much here Re: the autopilot relationships but it really depends on which unit you are talking about!

For example a honeywell system as found on most Boeings (The SPZ-1 if we want to be boring!) Will engage the Wing Leveler and Yaw Damper upon engagement of the AP. The modern Smiths autopilots as fitted to Airbus and Embraer engage the Yaw damper only upon engagement of AP1 or AP2. If you switch it on via the MDCU/FMC then it will also engage the Nav hold.

Older smiths systems will engage current altitude hold, wing level, and yaw damper.

In FS you normally see the compromise solution as you describe.With YD an WL engaged as you press AP. There are other relationships based on specific unit combinations and how you activate it. But unless you are really trying to replicate an exact unit then just stick with the initial WL and YD.

Yes there are Autospoiler systems and Auto Airbrake systems which automatically deploy on landing, The BAe 146 and Fokker 100 I mentioned has these modelled. On the BAe 146 these retract automatically on reaching 40kts, on the earlier versions of the Fokker they were programmed to retract only when the aircraft actually stopped, which I think Is an inaccuracy as they retract on the real model at 35kts if my memory serves.

Any other questions? im very bored today! <G>


FrankTurley@xxxxxxx wrote:
Dear Peter, Alex, Gerry and Alastair,
Thanks for coming back to me, but I must have asked the question about the inter related AP buttons very badly as nobody answered, perhaps I should rephrase in context -
I am trying to put together an autopilot gauge, and part of the process is to send messages to FS whenever an appropriate mouse button is clicked. Sometimes the process is just switching something on or off, but at other times more than one thing needs to be done. For example, when we switch the AP on, we also need to switch on the Wing Leveller and the Yaw Damper. If we switch the HDG on, we need to switch the Wing Leveller off. My question was are there any other inter relationships like this within the AP that I need to be aware of? Sorry I didn't ask very clearly.
Alex, thanks very much for your other answers, I now understand what the Yaw Damper does. Regarding the engine gauge questions, I think I need to do a bit more research as there is a wide variation between aircraft types. Reference the braking mechanisms, can I ask one further question please? I understand the autobrakes are armed before landing, and then automatically deployed on landing as you describe. Am I right in assuming that spoilers and airbrakes may be deployed to reduce speed while in the air, but can also be set up to auto deploy on landing, if the aircraft is so equipped? If so, is there any mechanism to prevent the airspeed dropping too low?
Gerry, I understand your point about needing the reference to the throttle setting on exit from AT, I have also done a throttle % gauge. The other one I find useful is a pitch trim gauge, on exit from the AP.
Alastair, thanks for the reference, I'm off for a quick shufti.
Thank you all very much for your help
Frank T.

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